Proteopedia - User contributions [en]

https://proteopedia.org/api.php?action=feedcontributions&feedformat=atom&user=Laura+McCauley Proteopedia - User contributions [en] 2026-09-21T15:25:06Z User contributions MediaWiki 1.43.8 https://proteopedia.org/index.php?title=ExbD&diff=1234908 ExbD 2011-04-26T05:43:54Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|left|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> ==Structure==<br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm (''see'' 3D structure 2PFU). Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found<ref name='Kampfenkel'>PMID: 1644779</ref>.<br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, therefore it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the [[TonB]] complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane<ref>PMID: 12193634</ref>. It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> The activity of ExbD can be affected with mutations of the single charged amino acid (here D25N) which lies close to the transmembrane region. This can also be said of the other transmembrane proteins ExbB, TolQ and TolR.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234907 ExbD 2011-04-26T05:43:04Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|left|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found<ref name='Kampfenkel'>PMID: 1644779</ref>.<br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, therefore it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the [[TonB]] complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane<ref>PMID: 12193634</ref>. It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> The activity of ExbD can be affected with mutations of the single charged amino acid (here D25N) which lies close to the transmembrane region. This can also be said of the other transmembrane proteins ExbB, TolQ and TolR.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234746 Ton 2011-04-25T18:06:24Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell<ref>PMID: 17347522</ref>, and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role<ref name='Held'>PMID: 12193634</ref>. For more information, see the respective pages for TonB, ExbB and ExbD.<br /> <br /> The Ton system can be exploited by group B Colicins {see [[Colicin]] for more details) which include<ref name="Cascales">PMID: 17347522</ref><ref name='Davies'>PMID: 124727</ref>:<br /> *[[Colicin 5]]<br /> *[[Colicin 6]]<br /> *[[Colicin 7]]<br /> *[[Colicin 8]]<br /> *[[Colicin 9]]<br /> *[[Colicin 10]]<br /> *[[Colicin Ia]]<br /> *[[Colicin Ib]]<br /> *[[Colicin B]]<br /> *[[Colicin D]]<br /> *[[Colicin M]]<br /> *[[Colicin V]]<br /> *[[Colicin Js]]<br /> *[[Colicin Y]]<br /> <br /> It is interesting to note that the name 'Ton' comes its resistance to the T1 phage<ref name='Davies'>PMID: 124727</ref>.<br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Tol&diff=1234745 Tol 2011-04-25T18:05:23Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TOL.jpg|400px|right|thumb| The Tol System<ref name='Witty'> PMID: 12169623</ref> and Operon<ref>http://ecoliwiki.net/colipedia/index.php/tolA:Expression</ref><ref>http://ecoliwiki.net/colipedia/index.php/tolB:Expression</ref> ]]<br /> ==Structure==<br /> The Tol system, also known as Tol-Pal, is a multi-protein complex found in the cell envelope of many gram-negative bacteria. It contains 7 proteins ([[TolQ]], [[TolR]], [[TolA]], [[TolB]], [[Pal]], [[YbgF]], [[YbgC]]), whose respective genes are organized into two operons as seen in the diagram<ref name="Cascales">PMID: 17347522</ref>.<br /> <br /> ===Interaction of Tol proteins===<br /> It was first suggested in 1994 that the Tol proteins interact to form a multiprotein complex of precise stoichiometry by Guihard et al, who showed that the level of Tol proteins at certain sites in the cell increases at a similar ratio with respect to one another when purified [[Colicin A]] is added to the whole cell<ref>PMID: 8119930</ref>.<br /> <br /> Cross-linking experiments show that<ref>PMID: 10419942</ref>:<br /> * the TolQ transmembrane domain interacts with the first TolQ transmembrane domain<br /> * the C-terminal and central domains of TolR are involved in its dimerization and this dimer interacts with the third transmembrane domain of TolQ<br /> * the C-terminal domain of TolR is also involved in the interaction with TolA<br /> <br /> More recent experiments<ref name="Walburger">PMID: 11994151</ref> show that these interactions also occur:<br /> * TolA also interacts with both YbgF and TolB<br /> * TolB has the ability to dimerize<br /> <br /> ==Function==<br /> As of yet, the cellular role of the Tol protein is unclear. However, there are several proposals for the different functions it may carry out:<br /> * the system components could be involved in the maintenance of the outer membrane as mutations of Tol proteins result in cells which leak the contents of the periplasm, as well as a hypersensitivity to some detergents, antibiotics and other agents<ref>PMID: 8955385</ref><br /> * it may play a role in anchoring the outer membrane to the peptidoglycan layer through the interactions that occur between TolB, Pal, Lpp and OmpA<ref name='Bouveret'>PMID 7744736</ref><br /> * possible regulation of porin activity due to the interactions seen between TolB and TolA<ref>PMID: 9393690</ref><br /> * the Tol-Pal system may have the ability to localise in the membrane to a site of cell constriction, taking part in invagination of the outer membrane during cell division<ref>PMID: 17233825</ref><br /> <br /> ===Interaction of Tol with Colicins===<br /> <structure load='2ivz' size='300' align='right' caption='Interaction of TolB and Colicin E9' (PDB entry [[2ivz]] | SCENE= Tol/Tolbcol/1 /><br /> It is interesting to note that the name 'Tol' derives from experiments which show that the ''tol'' mutant is tolerant to colicin action<ref name='Davies'>PMID: 1095546</ref>.<br /> <br /> The Tol-Pal system is used by group A colicins in order to translocate across the outer membrane, targeting mainly the inner membrane component TolA as well as TolQ and TolR. The colicins set up a translocon, constituting of the outer membrane receptor, translocator proteins and one or more periplasmic translocator proteins. The colicins recruit the Tol proteins using a Tol binding antigen, or epitope, which is embedded in the IUTD (Intrinsically Unstructured [[Translocation domain]]) found on the N-terminal (T-) domain of the colicin<ref>PMID: 21060316</ref>.<br /> <br /> A yeast two-hybrid screen was carried out in order to determine the interactions between colicins and the Tol-Pal system during the import of colicin<ref name="Walburger">PMID: 11994151</ref>. The screen showed that TolB dimerizes, and its amino terminal domain (D1) interacts with the periplasmic, C-terminal domain of TolA (TolAIII), whilst the central domain of TolA (TolAII) interacts with YbgF. It is the interaction between TolAIII and D1 that forms a "''trans''-envelope complex" which brings the inner and outer membranes closer together allowing for the uptake of [[Colicin A]]. The N-terminal of the group A colicins then interact with TolA and also sometimes TolB during translocation into the inner membrane.<br /> <br /> The structure shows the interaction between TolB and the <scene name='Tol/Tolbcolclose/1'>translocation domain</scene> of [[Colicin E9]].<br /> <br /> The Tol system can be exploited by the following group A colicins<ref name="Cascales">PMID: 17347522</ref><ref name='Davies'>PMID: 1095546</ref>:<br /> *[[Colicin A]]<br /> *[[Colicin E1]]<br /> *[[Colicin E2]]<br /> *[[Colicin E3]]<br /> *[[Colicin E4]]<br /> *[[Colicin E5]]<br /> *[[Colicin E6]]<br /> *[[Colicin E7]]<br /> *[[Colicin E8]]<br /> *[[Colicin E9]]<br /> *[[Colicin N]]<br /> *[[Colicin S4]]<br /> *[[Colicin K]]<br /> *[[Colicin U]]<br /> <br /> ==Regulation==<br /> It has been shown that the regulation of Tol genes is linked to the cell envelope stability<ref name="Cascales">PMID: 17347522</ref>. In studies with E. coli, the ''tol-pal'' genes have been induced by RcsC in response to cell envelope stress<ref>PMID: 8821933</ref>. RcsC is a transmembrane sensor kinase, and along with the cytoplasmic response regulator RcsB, makes up the RcsBC regulatory system<ref>PMID: 16166540</ref>. RcsBC is involved in the regulation of ''cps'' genes which code for the biosynthsis machinery of a major component for the capsula, cholanic acid.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Tol&diff=1234744 Tol 2011-04-25T18:04:54Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TOL.jpg|400px|right|thumb| The Tol System<ref name='Witty'> PMID: 12169623</ref> and Operon<ref>http://ecoliwiki.net/colipedia/index.php/tolA:Expression</ref><ref>http://ecoliwiki.net/colipedia/index.php/tolB:Expression</ref> ]]<br /> ==Structure==<br /> The Tol system, also known as Tol-Pal, is a multi-protein complex found in the cell envelope of many gram-negative bacteria. It contains 7 proteins ([[TolQ]], [[TolR]], [[TolA]], [[TolB]], [[Pal]], [[YbgF]], [[YbgC]]), whose respective genes are organized into two operons as seen in the diagram<ref name="Cascales">PMID: 17347522</ref>.<br /> <br /> ===Interaction of Tol proteins===<br /> It was first suggested in 1994 that the Tol proteins interact to form a multiprotein complex of precise stoichiometry by Guihard et al, who showed that the level of Tol proteins at certain sites in the cell increases at a similar ratio with respect to one another when purified [[Colicin A]] is added to the whole cell<ref>PMID: 8119930</ref>.<br /> <br /> Cross-linking experiments show that<ref>PMID: 10419942</ref>:<br /> * the TolQ transmembrane domain interacts with the first TolQ transmembrane domain<br /> * the C-terminal and central domains of TolR are involved in its dimerization and this dimer interacts with the third transmembrane domain of TolQ<br /> * the C-terminal domain of TolR is also involved in the interaction with TolA<br /> <br /> More recent experiments<ref name="Walburger">PMID: 11994151</ref> show that these interactions also occur:<br /> * TolA also interacts with both YbgF and TolB<br /> * TolB has the ability to dimerize<br /> <br /> ==Function==<br /> As of yet, the cellular role of the Tol protein is unclear. However, there are several proposals for the different functions it may carry out:<br /> * the system components could be involved in the maintenance of the outer membrane as mutations of Tol proteins result in cells which leak the contents of the periplasm, as well as a hypersensitivity to some detergents, antibiotics and other agents<ref>PMID: 8955385</ref><br /> * it may play a role in anchoring the outer membrane to the peptidoglycan layer through the interactions that occur between TolB, Pal, Lpp and OmpA<ref name='Bouveret'>PMID 7744736</ref><br /> * possible regulation of porin activity due to the interactions seen between TolB and TolA<ref>PMID: 9393690</ref><br /> * the Tol-Pal system may have the ability to localise in the membrane to a site of cell constriction, taking part in invagination of the outer membrane during cell division<ref>PMID: 17233825</ref><br /> <br /> ===Interaction of Tol with Colicins===<br /> <structure load='2ivz' size='300' align='right' caption='Interaction of TolB and Colicin E9' (PDB entry [[2ivz]] | SCENE= Tol/Tolbcol/1 /><br /> The name 'Tol' derives from experiments which show that the ''tol'' mutant is tolerant to colicin action<ref name='Davies'>PMID: 1095546</ref>.<br /> <br /> The Tol-Pal system is used by group A colicins in order to translocate across the outer membrane, targeting mainly the inner membrane component TolA as well as TolQ and TolR. The colicins set up a translocon, constituting of the outer membrane receptor, translocator proteins and one or more periplasmic translocator proteins. The colicins recruit the Tol proteins using a Tol binding antigen, or epitope, which is embedded in the IUTD (Intrinsically Unstructured [[Translocation domain]]) found on the N-terminal (T-) domain of the colicin<ref>PMID: 21060316</ref>.<br /> <br /> A yeast two-hybrid screen was carried out in order to determine the interactions between colicins and the Tol-Pal system during the import of colicin<ref name="Walburger">PMID: 11994151</ref>. The screen showed that TolB dimerizes, and its amino terminal domain (D1) interacts with the periplasmic, C-terminal domain of TolA (TolAIII), whilst the central domain of TolA (TolAII) interacts with YbgF. It is the interaction between TolAIII and D1 that forms a "''trans''-envelope complex" which brings the inner and outer membranes closer together allowing for the uptake of [[Colicin A]]. The N-terminal of the group A colicins then interact with TolA and also sometimes TolB during translocation into the inner membrane.<br /> <br /> The structure shows the interaction between TolB and the <scene name='Tol/Tolbcolclose/1'>translocation domain</scene> of [[Colicin E9]].<br /> <br /> The Tol system can be exploited by the following group A colicins<ref name="Cascales">PMID: 17347522</ref><ref name='Davies'>PMID: 1095546</ref>:<br /> *[[Colicin A]]<br /> *[[Colicin E1]]<br /> *[[Colicin E2]]<br /> *[[Colicin E3]]<br /> *[[Colicin E4]]<br /> *[[Colicin E5]]<br /> *[[Colicin E6]]<br /> *[[Colicin E7]]<br /> *[[Colicin E8]]<br /> *[[Colicin E9]]<br /> *[[Colicin N]]<br /> *[[Colicin S4]]<br /> *[[Colicin K]]<br /> *[[Colicin U]]<br /> <br /> ==Regulation==<br /> It has been shown that the regulation of Tol genes is linked to the cell envelope stability<ref name="Cascales">PMID: 17347522</ref>. In studies with E. coli, the ''tol-pal'' genes have been induced by RcsC in response to cell envelope stress<ref>PMID: 8821933</ref>. RcsC is a transmembrane sensor kinase, and along with the cytoplasmic response regulator RcsB, makes up the RcsBC regulatory system<ref>PMID: 16166540</ref>. RcsBC is involved in the regulation of ''cps'' genes which code for the biosynthsis machinery of a major component for the capsula, cholanic acid.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234743 Ton 2011-04-25T17:57:52Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell<ref>PMID: 17347522</ref>, and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role<ref name='Held'>PMID: 12193634</ref>. For more information, see the respective pages for TonB, ExbB and ExbD.<br /> <br /> The Ton system can be exploited by group B Colicins {see [[Colicin]] for more details) which include<ref name="Cascales">PMID: 17347522</ref><ref>PMID: 124727</ref>:<br /> *[[Colicin 5]]<br /> *[[Colicin 6]]<br /> *[[Colicin 7]]<br /> *[[Colicin 8]]<br /> *[[Colicin 9]]<br /> *[[Colicin 10]]<br /> *[[Colicin Ia]]<br /> *[[Colicin Ib]]<br /> *[[Colicin B]]<br /> *[[Colicin D]]<br /> *[[Colicin M]]<br /> *[[Colicin V]]<br /> *[[Colicin Js]]<br /> *[[Colicin Y]]<br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Tol&diff=1234742 Tol 2011-04-25T17:56:46Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TOL.jpg|400px|right|thumb| The Tol System<ref name='Witty'> PMID: 12169623</ref> and Operon<ref>http://ecoliwiki.net/colipedia/index.php/tolA:Expression</ref><ref>http://ecoliwiki.net/colipedia/index.php/tolB:Expression</ref> ]]<br /> ==Structure==<br /> The Tol system, also known as Tol-Pal, is a multi-protein complex found in the cell envelope of many gram-negative bacteria. It contains 7 proteins ([[TolQ]], [[TolR]], [[TolA]], [[TolB]], [[Pal]], [[YbgF]], [[YbgC]]), whose respective genes are organized into two operons as seen in the diagram<ref name="Cascales">PMID: 17347522</ref>.<br /> <br /> ===Interaction of Tol proteins===<br /> It was first suggested in 1994 that the Tol proteins interact to form a multiprotein complex of precise stoichiometry by Guihard et al, who showed that the level of Tol proteins at certain sites in the cell increases at a similar ratio with respect to one another when purified [[Colicin A]] is added to the whole cell<ref>PMID: 8119930</ref>.<br /> <br /> Cross-linking experiments show that<ref>PMID: 10419942</ref>:<br /> * the TolQ transmembrane domain interacts with the first TolQ transmembrane domain<br /> * the C-terminal and central domains of TolR are involved in its dimerization and this dimer interacts with the third transmembrane domain of TolQ<br /> * the C-terminal domain of TolR is also involved in the interaction with TolA<br /> <br /> More recent experiments<ref name="Walburger">PMID: 11994151</ref> show that these interactions also occur:<br /> * TolA also interacts with both YbgF and TolB<br /> * TolB has the ability to dimerize<br /> <br /> ==Function==<br /> As of yet, the cellular role of the Tol protein is unclear. However, there are several proposals for the different functions it may carry out:<br /> * the system components could be involved in the maintenance of the outer membrane as mutations of Tol proteins result in cells which leak the contents of the periplasm, as well as a hypersensitivity to some detergents, antibiotics and other agents<ref>PMID: 8955385</ref><br /> * it may play a role in anchoring the outer membrane to the peptidoglycan layer through the interactions that occur between TolB, Pal, Lpp and OmpA<ref name='Bouveret'>PMID 7744736</ref><br /> * possible regulation of porin activity due to the interactions seen between TolB and TolA<ref>PMID: 9393690</ref><br /> * the Tol-Pal system may have the ability to localise in the membrane to a site of cell constriction, taking part in invagination of the outer membrane during cell division<ref>PMID: 17233825</ref><br /> <br /> ===Interaction of Tol with Colicins===<br /> <structure load='2ivz' size='300' align='right' caption='Interaction of TolB and Colicin E9' (PDB entry [[2ivz]] | SCENE= Tol/Tolbcol/1 /><br /> The Tol-Pal system is used by group A colicins in order to translocate across the outer membrane, targeting mainly the inner membrane component TolA as well as TolQ and TolR. The colicins set up a translocon, constituting of the outer membrane receptor, translocator proteins and one or more periplasmic translocator proteins. The colicins recruit the Tol proteins using a Tol binding antigen, or epitope, which is embedded in the IUTD (Intrinsically Unstructured [[Translocation domain]]) found on the N-terminal (T-) domain of the colicin<ref>PMID: 21060316</ref>.<br /> <br /> A yeast two-hybrid screen was carried out in order to determine the interactions between colicins and the Tol-Pal system during the import of colicin<ref name="Walburger">PMID: 11994151</ref>. The screen showed that TolB dimerizes, and its amino terminal domain (D1) interacts with the periplasmic, C-terminal domain of TolA (TolAIII), whilst the central domain of TolA (TolAII) interacts with YbgF. It is the interaction between TolAIII and D1 that forms a "''trans''-envelope complex" which brings the inner and outer membranes closer together allowing for the uptake of [[Colicin A]]. The N-terminal of the group A colicins then interact with TolA and also sometimes TolB during translocation into the inner membrane.<br /> <br /> The structure shows the interaction between TolB and the <scene name='Tol/Tolbcolclose/1'>translocation domain</scene> of [[Colicin E9]].<br /> <br /> The Tol system can be exploited by the following group A colicins<ref name="Cascales">PMID: 17347522</ref><ref>PMID: 1095546</ref>:<br /> *[[Colicin A]]<br /> *[[Colicin E1]]<br /> *[[Colicin E2]]<br /> *[[Colicin E3]]<br /> *[[Colicin E4]]<br /> *[[Colicin E5]]<br /> *[[Colicin E6]]<br /> *[[Colicin E7]]<br /> *[[Colicin E8]]<br /> *[[Colicin E9]]<br /> *[[Colicin N]]<br /> *[[Colicin S4]]<br /> *[[Colicin K]]<br /> *[[Colicin U]]<br /> <br /> ==Regulation==<br /> It has been shown that the regulation of Tol genes is linked to the cell envelope stability<ref name="Cascales">PMID: 17347522</ref>. In studies with E. coli, the ''tol-pal'' genes have been induced by RcsC in response to cell envelope stress<ref>PMID: 8821933</ref>. RcsC is a transmembrane sensor kinase, and along with the cytoplasmic response regulator RcsB, makes up the RcsBC regulatory system<ref>PMID: 16166540</ref>. RcsBC is involved in the regulation of ''cps'' genes which code for the biosynthsis machinery of a major component for the capsula, cholanic acid.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Tol&diff=1234741 Tol 2011-04-25T17:53:41Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TOL.jpg|400px|right|thumb| The Tol System<ref name='Witty'> PMID: 12169623</ref> and Operon<ref>http://ecoliwiki.net/colipedia/index.php/tolA:Expression</ref><ref>http://ecoliwiki.net/colipedia/index.php/tolB:Expression</ref> ]]<br /> ==Structure==<br /> The Tol system, also known as Tol-Pal, is a multi-protein complex found in the cell envelope of many gram-negative bacteria. It contains 7 proteins ([[TolQ]], [[TolR]], [[TolA]], [[TolB]], [[Pal]], [[YbgF]], [[YbgC]]), whose respective genes are organized into two operons as seen in the diagram<ref name="Cascales">PMID: 17347522</ref>.<br /> <br /> ===Interaction of Tol proteins===<br /> It was first suggested in 1994 that the Tol proteins interact to form a multiprotein complex of precise stoichiometry by Guihard et al, who showed that the level of Tol proteins at certain sites in the cell increases at a similar ratio with respect to one another when purified [[Colicin A]] is added to the whole cell<ref>PMID: 8119930</ref>.<br /> <br /> Cross-linking experiments show that<ref>PMID: 10419942</ref>:<br /> * the TolQ transmembrane domain interacts with the first TolQ transmembrane domain<br /> * the C-terminal and central domains of TolR are involved in its dimerization and this dimer interacts with the third transmembrane domain of TolQ<br /> * the C-terminal domain of TolR is also involved in the interaction with TolA<br /> <br /> More recent experiments<ref name="Walburger">PMID: 11994151</ref> show that these interactions also occur:<br /> * TolA also interacts with both YbgF and TolB<br /> * TolB has the ability to dimerize<br /> <br /> ==Function==<br /> As of yet, the cellular role of the Tol protein is unclear. However, there are several proposals for the different functions it may carry out:<br /> * the system components could be involved in the maintenance of the outer membrane as mutations of Tol proteins result in cells which leak the contents of the periplasm, as well as a hypersensitivity to some detergents, antibiotics and other agents<ref>PMID: 8955385</ref><br /> * it may play a role in anchoring the outer membrane to the peptidoglycan layer through the interactions that occur between TolB, Pal, Lpp and OmpA<ref name='Bouveret'>PMID 7744736</ref><br /> * possible regulation of porin activity due to the interactions seen between TolB and TolA<ref>PMID: 9393690</ref><br /> * the Tol-Pal system may have the ability to localise in the membrane to a site of cell constriction, taking part in invagination of the outer membrane during cell division<ref>PMID: 17233825</ref><br /> <br /> ===Interaction of Tol with Colicins===<br /> <structure load='2ivz' size='300' align='right' caption='Interaction of TolB and Colicin E9' (PDB entry [[2ivz]] | SCENE= Tol/Tolbcol/1 /><br /> The Tol-Pal system is used by group A colicins in order to translocate across the outer membrane, targeting mainly the inner membrane component TolA as well as TolQ and TolR. The colicins set up a translocon, constituting of the outer membrane receptor, translocator proteins and one or more periplasmic translocator proteins. The colicins recruit the Tol proteins using a Tol binding antigen, or epitope, which is embedded in the IUTD (Intrinsically Unstructured [[Translocation domain]]) found on the N-terminal (T-) domain of the colicin<ref>PMID: 21060316</ref>.<br /> <br /> A yeast two-hybrid screen was carried out in order to determine the interactions between colicins and the Tol-Pal system during the import of colicin<ref name="Walburger">PMID: 11994151</ref>. The screen showed that TolB dimerizes, and its amino terminal domain (D1) interacts with the periplasmic, C-terminal domain of TolA (TolAIII), whilst the central domain of TolA (TolAII) interacts with YbgF. It is the interaction between TolAIII and D1 that forms a "''trans''-envelope complex" which brings the inner and outer membranes closer together allowing for the uptake of [[Colicin A]]. The N-terminal of the group A colicins then interact with TolA and also sometimes TolB during translocation into the inner membrane.<br /> <br /> The structure shows the interaction between TolB and the <scene name='Tol/Tolbcolclose/1'>translocation domain</scene> of [[Colicin E9]].<br /> <br /> The Tol system can be exploited by the following group A colicins:<br /> *[[Colicin A]]<br /> *[[Colicin E1]]<br /> *[[Colicin E2]]<br /> *[[Colicin E3]]<br /> *[[Colicin E4]]<br /> *[[Colicin E5]]<br /> *[[Colicin E6]]<br /> *[[Colicin E7]]<br /> *[[Colicin E8]]<br /> *[[Colicin E9]]<br /> *[[Colicin N]]<br /> *[[Colicin S4]]<br /> *[[Colicin K]]<br /> *[[Colicin U]]<br /> <br /> ==Regulation==<br /> It has been shown that the regulation of Tol genes is linked to the cell envelope stability<ref name="Cascales">PMID: 17347522</ref>. In studies with E. coli, the ''tol-pal'' genes have been induced by RcsC in response to cell envelope stress<ref>PMID: 8821933</ref>. RcsC is a transmembrane sensor kinase, and along with the cytoplasmic response regulator RcsB, makes up the RcsBC regulatory system<ref>PMID: 16166540</ref>. RcsBC is involved in the regulation of ''cps'' genes which code for the biosynthsis machinery of a major component for the capsula, cholanic acid.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234740 Ton 2011-04-25T17:51:33Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell<ref>PMID: 17347522</ref>, and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role<ref name='Held'>PMID: 12193634</ref>. For more information, see the respective pages for TonB, ExbB and ExbD.<br /> <br /> The Ton system can be exploited by group B Colicins {see [[Colicin]] for more details) which include:<br /> *[[Colicin 5]]<br /> *[[Colicin 6]]<br /> *[[Colicin 7]]<br /> *[[Colicin 8]]<br /> *[[Colicin 9]]<br /> *[[Colicin 10]]<br /> *[[Colicin Ia]]<br /> *[[Colicin Ib]]<br /> *[[Colicin B]]<br /> *[[Colicin D]]<br /> *[[Colicin M]]<br /> *[[Colicin V]]<br /> *[[Colicin Js]]<br /> *[[Colicin Y]]<br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234739 Ton 2011-04-25T17:51:00Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell<ref>PMID: 17347522</ref>, and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role<ref name='Held'>PMID: 12193634</ref>. For more information, see the respective pages for TonB, ExbB and ExbD.<br /> <br /> The Ton system can be exploited by group B Colicins {see [[Colicin]] for more details) which include:<br /> *[[Colicin 5]]<br /> *[[Colicin 6]]<br /> *[[Colicin 7]]<br /> *[[Colicin 8]]<br /> *[[Colicin 9]]<br /> *[[Colicin 10]]<br /> *[[Colicin 1a]]<br /> *[[Colicin 1b]]<br /> *[[Colicin B]]<br /> *[[Colicin D]]<br /> *[[Colicin M]]<br /> *[[Colicin V]]<br /> *[[Colicin Js]]<br /> *[[Colicin Y]]<br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234738 Ton 2011-04-25T17:47:36Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell<ref>PMID: 17347522</ref>, and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role<ref name='Held'>PMID: 12193634</ref>. For more information, see the respective pages for TonB, ExbB and ExbD.<br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> ==Regulation==<br /> <br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TonB&diff=1234737 TonB 2011-04-25T17:42:58Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1xx3 | PDB=1xx3 | SCENE= TonB/Ctdtonb/1 }}<br /> ==Structure==<br /> The structure to the right (1XX3) shows the structure of TonB. The protein spans the periplasm <ref>PMID: 16741125</ref>, with the C-terminus of TonB spanning from residues ~150 to 239<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ==Function==<br /> TonB is involved in the uptake of iron as a component of the TonB/[[ExbB]]/[[ExbD]] complex of the [[Ton]] system. It's activity is determined by the presence of ExbB and ExbD<ref name='Kampfenkel'>PMID: 8449962</ref>. The C-terminus of TonB interacts with outer membrane transporters, known as TonB-dependent outer membrane transporters (TBDTs)<ref name=Wiener'>PMID: 16039843</ref>, allowing the translocation of biochemical molecules between the inner and outer membrane<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ===Interaction with ExbB/ExbD===<br /> TonB and ExbD bind to ExbB in a protein complex that prevents the degradation of the TonB protein. TonB and ExbD are anchored to the cytoplasmic membrane via their N-terminal hydrophobic sequences, with the rest of the protein complex extending into the periplasmic space, allowing for interaction with outer membrane proteins.<ref name='Kampfenkel'>PMID: 8449962</ref><br /> <br /> TonB takes on the role of an energy transducer, while ExbB and ExbD are involved in the transport of biochemical molecules. In order for sucessful energy transduction to occur, there are processes that must occur<ref name='Held'>PMID: 12193634</ref>:<br /> #TonB must couple to the proton gradient of the cytoplasmic membrane<br /> #TonB must convert its association with the outer membrane, for which it has high affinity, to that with the cytoplasmic membrane, which is also thought to be high affinity.<br /> <br /> ===BtuB-TonB Complex===<br /> {{STRUCTURE_2gsk | PDB=2gsk | SCENE= BtuB-TonB_Complex/Btubtonbcomplex/1 }}<br /> As shown in the 3D structure to the right (2GSK), TonB complexes with [[BtuB]] in order to aid the transport of nutrients such as cobalamins<ref name='Cadieux'>PMID 11029413</ref> across the outer membrane by incorporating the proton-motive force into the outer membrane.<ref name='Shultis'>PMID: 16741124</ref> TonB attaches to BtuB on the periplasmic side of the 614 amino acid BtuB protein<ref name='Shultis'> PMID: 16741124</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TonB&diff=1234736 TonB 2011-04-25T17:42:13Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1xx3 | PDB=1xx3 | SCENE= TonB/Ctdtonb/1 }}<br /> <br /> ==Structure==<br /> The structure to the right (1XX3) shows the structure of TonB. The protein spans the periplasm <ref>PMID: 16741125</ref>, with the C-terminus of TonB spanning from residues ~150 to 239<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ==Function==<br /> TonB is involved in the uptake of iron as a component of the TonB/[[ExbB]]/[[ExbD]] complex of the [[Ton]] system. It's activity is determined by the presence of ExbB and ExbD<ref name='Kampfenkel'>PMID: 8449962</ref>. The C-terminus of TonB interacts with outer membrane transporters, known as TonB-dependent outer membrane transporters (TBDTs)<ref name=Wiener'>PMID: 16039843</ref>, allowing the translocation of biochemical molecules between the inner and outer membrane<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ===Interaction with ExbB/ExbD===<br /> TonB and ExbD bind to ExbB in a protein complex that prevents the degradation of the TonB protein. TonB and ExbD are anchored to the cytoplasmic membrane via their N-terminal hydrophobic sequences, with the rest of the protein complex extending into the periplasmic space, allowing for interaction with outer membrane proteins.<ref name='Kampfenkel'>PMID: 8449962</ref><br /> <br /> TonB takes on the role of an energy transducer, while ExbB and ExbD are involved in the transport of biochemical molecules. In order for sucessful energy transduction to occur, there are processes that must occur<ref name='Held'>PMID: 12193634</ref>:<br /> #TonB must couple to the proton gradient of the cytoplasmic membrane<br /> #TonB must convert its association with the outer membrane, for which it has high affinity, to that with the cytoplasmic membrane, which is also thought to be high affinity.<br /> <br /> ===BtuB-TonB Complex===<br /> As shown in the 3D structure to the right (2GSK), TonB complexes with [[BtuB]] in order to aid the transport of nutrients such as cobalamins<ref name='Cadieux'>PMID 11029413</ref> across the outer membrane by incorporating the proton-motive force into the outer membrane.<ref name='Shultis'>PMID: 16741124</ref> TonB attaches to BtuB on the periplasmic side of the 614 amino acid BtuB protein<ref name='Shultis'> PMID: 16741124</ref>.<br /> <br /> {{STRUCTURE_2gsk | PDB=2gsk | SCENE= BtuB-TonB_Complex/Btubtonbcomplex/1 }}<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Ton&diff=1234735 Ton 2011-04-25T17:27:44Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TON.jpg|400px|right|thumb| The Ton System<ref name='Witty'> PMID: 12169623</ref>]]<br /> <br /> ==Structure==<br /> The Ton system comprises of the triumvirate [[TonB]]/[[ExbB]]/[[ExbD]] inner membrane complex.<br /> <br /> ==Function==<br /> The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell.<ref>PMID: 17347522</ref><br /> <br /> ==Interaction of Ton proteins==<br /> Like in the [[Tol]] complex, the Ton system proteins interact with each other<ref>PMID: 9811664</ref>:<br /> # the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.<br /> # ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction<br /> <br /> ==Regulation==<br /> <br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgC&diff=1234734 YbgC 2011-04-25T17:22:29Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_2pzh | PDB=2pzh | SCENE= }}<br /> YbgCis believed to have first appeared in the [[Tol]] complex with the separation of the δε proteobacteria from the αβγ proteobacteria<ref name='Sturgis'>PMID: 11200223</ref>.<br /> <br /> ==Structure==<br /> YbgC is a cytoplasmic protein in the Tol-[[Pal]] complex<ref>PMID: 11994151</ref>. In ''Helicobacter pylori'', the protein is part of a 'hot-dog' family of proteins, with an epsilongamma tetrameric arrangement<ref name='Angelini'>PMID: 18338382</ref>.<br /> <br /> ==Function==<br /> The protein displays thioesterase activity towards acyl-CoA thioesters<ref name='Angelini'>PMID: 18338382</ref>, and has a strong sequence conservation with its active site residues with other proteins of a similar function<ref>PMID: 9837940</ref> for example with the ''Pseudonomas'' sp. strain CBS3 4-hydroxybenzoyl-CoA thioesterase<ref>PMID: 11959124</ref>.<br /> <br /> However, its role within the Tol complex itself remains unknown, although it may be involved in the acetylation of another protein within the complex, with the role of an activity-regulator<ref name='Sturgis'>PMID: 11200223</ref>. It is also thought to be involved in the cell division complex of Tol-Pal<ref name='Angelini'>PMID: 18338382</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgC&diff=1234733 YbgC 2011-04-25T17:22:00Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_2pzh | PDB=2pzh | SCENE= }}<br /> YbgCis believed to have first appeared in the [[Tol]] complex with the separation of the δε proteobacteria from the αβγ proteobacteria<ref name='Sturgis'>PMID: 11200223</ref>.<br /> <br /> ==Structure==<br /> YbgC is a cytoplasmic protein in the Tol-[[Pal]] complex<ref>PMID: 11994151</ref>. In ''Helicobacter pylori'', the protein is part of a 'hot-dog' family of proteins, with an epsilongamma tetrameric arrangement<ref name-'Angelini'>PMID: 18338382</ref>.<br /> <br /> ==Function==<br /> The protein displays thioesterase activity towards acyl-CoA thioesters<ref name='Angelini'>PMID: 18338382</ref>, and has a strong sequence conservation with its active site residues with other proteins of a similar function<ref>PMID: 9837940</ref> for example with the ''Pseudonomas'' sp. strain CBS3 4-hydroxybenzoyl-CoA thioesterase<ref>PMID: 11959124</ref>.<br /> <br /> However, its role within the Tol complex itself remains unknown, although it may be involved in the acetylation of another protein within the complex, with the role of an activity-regulator<ref name='Sturgis'>PMID: 11200223</ref>. It is also thought to be involved in the cell division complex of Tol-Pal<ref name-'Angelini'>PMID: 18338382</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234732 YbgF 2011-04-25T16:46:35Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the [[Tol]] complex is recruited to the area of septation, or also during invagination<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of [[Colicin A]] into the cytoplasm<ref name='Walberger'>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in [[TolA]], with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> Studies have shown that inactivation of the YbgF gene results in no discernible change in the activity of Tol<ref name='Walberger'>PMID: 11994151</ref>. Therefore, replacing the protein with another would not rescue any lost function. Future research may look into comparison of different gram negative bacteria in order to determine if the function is conserved. One particular organism that is known to not have this domain conserved is ''Chlamydiae''<ref name='Krachler'>PMID: 20816983</ref>. Future research may look into the functioning of its Tol system, with a the possible addition of the YbgF domain to study what effect this might have.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolB&diff=1234731 TolB 2011-04-25T16:45:26Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1c5k | PDB=1c5k | SCENE= TolB/Tolb/1 }}<br /> ==Structure==<br /> TolB is a 44-kDa periplasmic protein partially associated with the outer membrane<ref name='Bouveret'>PMID: 7744736</ref>. It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which [[Pal]] and [[Colicin E9]] bind)<ref name='Bonsor'>PMID: 19696740</ref>. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.<br /> <br /> ==Function==<br /> The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of [[TolA]] in the inner membrane<ref name='Bonsor'>PMID: 19696740</ref>.<br /> <br /> TolB has been shown to be essential for the function of the [[Tol]] system in ''Escherichia coli''<ref name='Bonsor'>PMID: 19696740</ref> by generating an allosteric signal based on a conformational switch in the β-propeller region. TolB has also been shown to interact with the porins of Escherichia coli, in particular OmpF, OmpC, PhoE and LamB, but not OmpA or any of their denatured counterparts. It has been proposed that the whole Tol complex plays a role in this association, although "tol" mutants do not prevent this assembly completely therefore the Tol system may be involved kinetically, not directly<ref>PMID: 9393690</ref>.<br /> <br /> ==The TolB-Pal Complex==<br /> <structure load='2w8b' size='300' align='left' caption='Interaction of TolB and Pal' (PDB entry [[2w8b]] | SCENE= TolB/Tolbpal/1 />The TolB-[[Pal]] complex is involved in maintaining the outer membrane integrity. Upon binding, TolB and Pal undergo a conformational change , the result of which is crucial for further interactions with other proteins<ref name='Godlewska'>PMID: 19519769</ref>. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see [[Colicin]] for further information)<ref name='Bonsor'>PMID: 17375930</ref>.<br /> <br /> To study the interaction of TolB with Pal, two studies were carried out<ref name='Bouveret'>PMID 7744736</ref>: TolBBep (tagging TolB for immunoprecipitation), which allows the associated proteins to remain in contact with TolB, and ''in vivo'' cross-linking experiments with formaldehyde. Immunoprecipitation gave the result that Pal co-precipitates with TolBBep, while the cross-linking showed that in the present of Pal, the two products migrated close to each other, but in the absence of Pal, neither band was present, demonstrating an interaction between the two. These two experiments showed that TolB directly interacts with Pal, and that this interaction is responsible for maintaining the association of TolB with the membrane.<br /> <br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolA&diff=1234730 TolA 2011-04-25T16:39:59Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1s62 | PDB=1s62 | SCENE= TolA/Ctdtola/1 }}<br /> ==Structure==<br /> TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref name='Lazzaroni'>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> ===C-terminal Domain===<br /> The C-terminal domain of TolA is directly involved with the N-terminal of both Colicin and the phage minor coat gene 3 protein<ref name='Deprez'>PMID: 15701516</ref>.<br /> <br /> ===Comparison with TonB===<br /> TolA and [[TonB]] have been shown to have a common evolutionary origin: although the two proteins can undergo domain swapping, this is difficult to achieve. Through sedimentation experiments, it has been shown that TonB is able to remain as a monomer and form a TolA-like fold, but leaves an exposed β-ribbon which would need to undergo extensive conformational changes. TolA does have the potential to dimerise, but it is highly unlike that it will do so. Nevertheless, the structural similarities between these two proteins clearly indicates an evolutionary relationship, even if the functional properties have divulged<ref name='Witty'> PMID: 12169623</ref>.<br /> <br /> ==Function==<br /> Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see [[Colicin]]) and the DNA of filamentous bacteriophages<ref name='Deprez'>PMID: 15701516</ref>, and has also been shown to be involved in the bacterial sensitivity to these groups<ref name='Lazzaroni'>PMID: 7853390</ref>, in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)<ref name='Schendel'>PMID: 9171417</ref>.<br /> <br /> ===TolA and Colicin Uptake===<br /> Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein<ref name='Deprez'>PMID: 15701516</ref>.<br /> <br /> TolA interacts with different group A colicins in different ways<ref name='Schendel'>PMID: 9171417</ref>:<br /> * [[Colicin E1]] requires different structural features of TolA to be transported than the other group A colicins, including [[Colicin E3]], [[Colicin N]] and [[Colicin A]]. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins<br /> * The other colicins require additional receptors in order to bind initially to the outer membrane<br /> *Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Tol&diff=1234729 Tol 2011-04-25T16:35:47Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TOL.jpg|400px|right|thumb| The Tol System<ref name='Witty'> PMID: 12169623</ref> and Operon<ref>http://ecoliwiki.net/colipedia/index.php/tolA:Expression</ref><ref>http://ecoliwiki.net/colipedia/index.php/tolB:Expression</ref> ]]<br /> ==Structure==<br /> The Tol system, also known as Tol-Pal, is a multi-protein complex found in the cell envelope of many gram-negative bacteria. It contains 7 proteins ([[TolQ]], [[TolR]], [[TolA]], [[TolB]], [[Pal]], [[YbgF]], [[YbgC]]), whose respective genes are organized into two operons as seen in the diagram<ref name="Cascales">PMID: 17347522</ref>.<br /> <br /> ===Interaction of Tol proteins===<br /> It was first suggested in 1994 that the Tol proteins interact to form a multiprotein complex of precise stoichiometry by Guihard et al, who showed that the level of Tol proteins at certain sites in the cell increases at a similar ratio with respect to one another when purified [[Colicin A]] is added to the whole cell<ref>PMID: 8119930</ref>.<br /> <br /> Cross-linking experiments show that<ref>PMID: 10419942</ref>:<br /> * the TolQ transmembrane domain interacts with the first TolQ transmembrane domain<br /> * the C-terminal and central domains of TolR are involved in its dimerization and this dimer interacts with the third transmembrane domain of TolQ<br /> * the C-terminal domain of TolR is also involved in the interaction with TolA<br /> <br /> More recent experiments<ref name="Walburger">PMID: 11994151</ref> show that these interactions also occur:<br /> * TolA also interacts with both YbgF and TolB<br /> * TolB has the ability to dimerize<br /> <br /> ==Function==<br /> As of yet, the cellular role of the Tol protein is unclear. However, there are several proposals for the different functions it may carry out:<br /> * the system components could be involved in the maintenance of the outer membrane as mutations of Tol proteins result in cells which leak the contents of the periplasm, as well as a hypersensitivity to some detergents, antibiotics and other agents<ref>PMID: 8955385</ref><br /> * it may play a role in anchoring the outer membrane to the peptidoglycan layer through the interactions that occur between TolB, Pal, Lpp and OmpA<ref name='Bouveret'>PMID 7744736</ref><br /> * possible regulation of porin activity due to the interactions seen between TolB and TolA<ref>PMID: 9393690</ref><br /> * the Tol-Pal system may have the ability to localise in the membrane to a site of cell constriction, taking part in invagination of the outer membrane during cell division<ref>PMID: 17233825</ref><br /> <br /> ===Interaction of Tol with Colicins===<br /> <structure load='2ivz' size='300' align='right' caption='Interaction of TolB and Colicin E9' (PDB entry [[2ivz]] | SCENE= Tol/Tolbcol/1 /><br /> The Tol-Pal system is used by group A colicins in order to translocate across the outer membrane, targeting mainly the inner membrane component TolA as well as TolQ and TolR. The colicins set up a translocon, constituting of the outer membrane receptor, translocator proteins and one or more periplasmic translocator proteins. The colicins recruit the Tol proteins using a Tol binding antigen, or epitope, which is embedded in the IUTD (Intrinsically Unstructured [[Translocation domain]]) found on the N-terminal (T-) domain of the colicin<ref>PMID: 21060316</ref>.<br /> <br /> A yeast two-hybrid screen was carried out in order to determine the interactions between colicins and the Tol-Pal system during the import of colicin<ref name="Walburger">PMID: 11994151</ref>. The screen showed that TolB dimerizes, and its amino terminal domain (D1) interacts with the periplasmic, C-terminal domain of TolA (TolAIII), whilst the central domain of TolA (TolAII) interacts with YbgF. It is the interaction between TolAIII and D1 that forms a "''trans''-envelope complex" which brings the inner and outer membranes closer together allowing for the uptake of [[Colicin A]]. The N-terminal of the group A colicins then interact with TolA and also sometimes TolB during translocation into the inner membrane.<br /> <br /> The structure shows the interaction between TolB and the <scene name='Tol/Tolbcolclose/1'>translocation domain</scene> of [[Colicin E9]].<br /> <br /> ==Regulation==<br /> It has been shown that the regulation of Tol genes is linked to the cell envelope stability<ref name="Cascales">PMID: 17347522</ref>. In studies with E. coli, the ''tol-pal'' genes have been induced by RcsC in response to cell envelope stress<ref>PMID: 8821933</ref>. RcsC is a transmembrane sensor kinase, and along with the cytoplasmic response regulator RcsB, makes up the RcsBC regulatory system<ref>PMID: 16166540</ref>. RcsBC is involved in the regulation of ''cps'' genes which code for the biosynthsis machinery of a major component for the capsula, cholanic acid.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolQ&diff=1234728 TolQ 2011-04-25T16:33:10Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TolQ.jpg|600px|right|thumb| The TolQ Membrane-spanning domains <ref>PMID: 8662905</ref>]]<br /> ==Structure==<br /> TolQ is a polytopic protein located in the inner (cytoplasmic) membrane, containing approximately 230 amino acids. There are three membrane spanning segments in TolQ with each segment containing an α-helix<ref>PMID: 7853390</ref>. TM1 is connected to TM2 via a large cytoplasmic loop, with the N-terminal ending in the periplasm. This topology is also found in [[ExbB]], which can be explained by the similar sequence shared by both proteins<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> It has been shown that 4 to 6 TolQ molecules associate in the TolQRA complex, and that they form multimers which interact with the transmembrane helices (TMH) of TolQ, [[TolR]] and [[TolA]]<ref> PMID: 21285349</ref>. The multimers are formed by the three TMHs of TolQ, the last of which undergo a conformational change to form a hairpin, while the first TMH forms an intermolecular interaction<ref name='Vianney'> PMID:8300535</ref>.<br /> <br /> ==Function==<br /> TolQ plays an important role in the maintenance of the bacterial envelope integrity as well as the import of filamentous bacteriophage and group A colicins<ref name='Vianney'> PMID:8300535</ref>.<br /> <br /> Loss of TolQ function can be partially replaced by ExbB and vice versa - reduced activities of either of these proteins via a mutant form can be reversed by introducing double mutants<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolR&diff=1234727 TolR 2011-04-25T16:32:01Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_2jwk | PDB=2jwk | SCENE= TolR/Tolrstructure/1 }}<br /> <br /> ==Structure==<br /> TolR is a bitopic protein located in the inner membrane and consists of three domains: domain I (from residues 1 to 43 and including the transmembrane domain between residues 23 to 43), domain II and domain III from residues 117 to 142<ref name='Journet'>PMID: 10419942</ref>. Domains II and III have the ability to dimerize, but unlike domains I and III, domain II is poorly conserved<ref>PMID: 11994151</ref>.<br /> <br /> Domain III has been suggested to form an amphiphilic α-helix, which play an essential role in the functional assembly of the [[Tol]] complex<ref name='Lazzaroni'>PMID: 7853390</ref>.<br /> <br /> ==Function==<br /> TolR has been shown to exhibit several functions<ref name='Journet'>PMID: 10419942</ref>:<br /> # Interactions with other Tol proteins: Domain I is important for the interactions between [[TolA]] and [[TolQ]], as deletion of this domain resulted in no cross-linkages formed between these proteins<ref name='Journet'>PMID: 10419942</ref>. Domain III of TolR has also been shown to be involved in the TolQ-TolR interaction, but not directly linked<ref name='Lazzaroni'>PMID: 7853390</ref>. However, even when deleted there is still cross linking between TolR and TolQ showing that domain III does not affect the interaction between the two proteins, but could instead affect the function of TolR<ref name='Journet'>PMID: 10419942</ref>. As domain III has not been shown to interact directly with TolA or TolQ, the function of TolR could be affected ''indirectly'' by domain III altering the conformation of domain I thereby affecting the interaction between TolA/TolQ-TolR. <br /> # [[Colicin A]] import<br /> # Maintaining cell envelope integrity<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolA&diff=1234726 TolA 2011-04-25T16:30:16Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1s62 | PDB=1s62 | SCENE= TolA/Ctdtola/1 }}<br /> ==Structure==<br /> TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> ===C-terminal Domain===<br /> The C-terminal domain of TolA is directly involved with the N-terminal of both Colicin and the phage minor coat gene 3 protein<ref>PMID: 15701516</ref>.<br /> <br /> ===Comparison with TonB===<br /> TolA and [[TonB]] have been shown to have a common evolutionary origin: although the two proteins can undergo domain swapping, this is difficult to achieve. Through sedimentation experiments, it has been shown that TonB is able to remain as a monomer and form a TolA-like fold, but leaves an exposed β-ribbon which would need to undergo extensive conformational changes. TolA does have the potential to dimerise, but it is highly unlike that it will do so. Nevertheless, the structural similarities between these two proteins clearly indicates an evolutionary relationship, even if the functional properties have divulged<ref name='Witty'> PMID: 12169623</ref>.<br /> <br /> ==Function==<br /> Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see [[Colicin]]) and the DNA of filamentous bacteriophages<ref name='Deprez'>PMID: 15701516</ref>, and has also been shown to be involved in the bacterial sensitivity to these groups<ref>PMID: 7853390</ref>, in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)<ref name='Schendel">PMID: 9171417</ref>.<br /> <br /> ===TolA and Colicin Uptake===<br /> Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein<ref>PMID: 15701516</ref>.<br /> <br /> TolA interacts with different group A colicins in different ways<ref name='Schendel">PMID: 9171417</ref>:<br /> * [[Colicin E1]] requires different structural features of TolA to be transported than the other group A colicins, including [[Colicin E3]], [[Colicin N]] and [[Colicin A]]. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins<br /> * The other colicins require additional receptors in order to bind initially to the outer membrane<br /> *Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolA&diff=1234725 TolA 2011-04-25T16:29:53Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1s62 | PDB=1s62 | SCENE= TolA/Ctdtola/1 }}<br /> ==Structure==<br /> TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> ===C-terminal Domain===<br /> The C-terminal domain of TolA is directly involved with the N-terminal of both [[Colicin]] and the phage minor coat gene 3 protein<ref>PMID: 15701516</ref>.<br /> <br /> ===Comparison with TonB===<br /> TolA and [[TonB]] have been shown to have a common evolutionary origin: although the two proteins can undergo domain swapping, this is difficult to achieve. Through sedimentation experiments, it has been shown that TonB is able to remain as a monomer and form a TolA-like fold, but leaves an exposed β-ribbon which would need to undergo extensive conformational changes. TolA does have the potential to dimerise, but it is highly unlike that it will do so. Nevertheless, the structural similarities between these two proteins clearly indicates an evolutionary relationship, even if the functional properties have divulged<ref name='Witty'> PMID: 12169623</ref>.<br /> <br /> ==Function==<br /> Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see [[Colicin]]) and the DNA of filamentous bacteriophages<ref name='Deprez'>PMID: 15701516</ref>, and has also been shown to be involved in the bacterial sensitivity to these groups<ref>PMID: 7853390</ref>, in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)<ref name='Schendel">PMID: 9171417</ref>.<br /> <br /> ===TolA and Colicin Uptake===<br /> Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein<ref>PMID: 15701516</ref>.<br /> <br /> TolA interacts with different group A colicins in different ways<ref name='Schendel">PMID: 9171417</ref>:<br /> * [[Colicin E1]] requires different structural features of TolA to be transported than the other group A colicins, including [[Colicin E3]], [[Colicin N]] and [[Colicin A]]. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins<br /> * The other colicins require additional receptors in order to bind initially to the outer membrane<br /> *Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolA&diff=1234724 TolA 2011-04-25T16:29:21Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1s62 | PDB=1s62 | SCENE= TolA/Ctdtola/1 }}<br /> ==Structure==<br /> TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> ===C-terminal Domain===<br /> The C-terminal domain of TolA is directly involved with the N-terminal of both [[Colicin]] and the phage minor coat gene 3 protein<ref>PMID: 15701516</ref>.<br /> <br /> ===Comparison with TonB===<br /> TolA and [[TonB]] have been shown to have a common evolutionary origin: although the two proteins can undergo domain swapping, this is difficult to achieve. Through sedimentation experiments, it has been shown that TonB is able to remain as a monomer and form a TolA-like fold, but leaves an exposed β-ribbon which would need to undergo extensive conformational changes. TolA does have the potential to dimerise, but it is highly unlike that it will do so. Nevertheless, the structural similarities between these two proteins clearly indicates an evolutionary relationship, even if the functional properties have divulged<ref name='Witty'> PMID: 12169623</ref>.<br /> <br /> ==Function==<br /> Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them<ref name='Sharyn'>PMID: 8416897</ref>.<br /> <br /> TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see [[Colicin]]) and the DNA of filamentous bacteriophages<ref name='Deprez'>PMID: 15701516</ref>, and has also been shown to be involved in the bacterial sensitivity to these groups<ref>PMID: 7853390</ref>, in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)<ref name='Schendel">PMID: 9171417</ref>.<br /> <br /> ===TolA and Colicin Uptake===<br /> Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein. <ref>PMID: 15701516</ref><br /> <br /> TolA interacts with different group A colicins in different ways<ref name='Schendel">PMID: 9171417</ref>:<br /> * [[Colicin E1]] requires different structural features of TolA to be transported than the other group A colicins, including [[Colicin E3]], [[Colicin N]] and [[Colicin A]]. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins<br /> * The other colicins require additional receptors in order to bind initially to the outer membrane<br /> *Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolB&diff=1234723 TolB 2011-04-25T16:25:07Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1c5k | PDB=1c5k | SCENE= TolB/Tolb/1 }}<br /> ==Structure==<br /> TolB is a 44-kDa periplasmic protein partially associated with the outer membrane<ref name='Bouveret'>PMID: 7744736</ref>. It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which [[Pal]] and [[Colicin E9]] bind)<ref>PMID: 19696740</ref>. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.<br /> <br /> ==Function==<br /> The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of [[TolA]] in the inner membrane<ref>PMID: 19696740</ref>.<br /> <br /> TolB has been shown to be essential for the function of the [[Tol]] system in ''Escherichia coli''<ref>PMID: 19696740</ref> by generating an allosteric signal based on a conformational switch in the β-propeller region. TolB has also been shown to interact with the porins of Escherichia coli, in particular OmpF, OmpC, PhoE and LamB, but not OmpA or any of their denatured counterparts. It has been proposed that the whole Tol complex plays a role in this association, although "tol" mutants do not prevent this assembly completely therefore the Tol system may be involved kinetically, not directly<ref>PMID: 9393690</ref>.<br /> <br /> ==The TolB-Pal Complex==<br /> <structure load='2w8b' size='300' align='left' caption='Interaction of TolB and Pal' (PDB entry [[2w8b]] | SCENE= TolB/Tolbpal/1 />The TolB-[[Pal]] complex is involved in maintaining the outer membrane integrity. Upon binding, TolB and Pal undergo a conformational change , the result of which is crucial for further interactions with other proteins<ref name='Godlewska'>PMID: 19519769</ref>. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see [[Colicin]] for further information)<ref name='Bonsor'>PMID: 17375930</ref>.<br /> <br /> To study the interaction of TolB with Pal, two studies were carried out<ref name='Bouveret'>PMID 7744736</ref>: TolBBep (tagging TolB for immunoprecipitation), which allows the associated proteins to remain in contact with TolB, and ''in vivo'' cross-linking experiments with formaldehyde. Immunoprecipitation gave the result that Pal co-precipitates with TolBBep, while the cross-linking showed that in the present of Pal, the two products migrated close to each other, but in the absence of Pal, neither band was present, demonstrating an interaction between the two. These two experiments showed that TolB directly interacts with Pal, and that this interaction is responsible for maintaining the association of TolB with the membrane.<br /> <br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolB&diff=1234722 TolB 2011-04-25T16:24:27Z

<p>Laura McCauley: </p> <hr /> <div>==Structure==<br /> {{STRUCTURE_1c5k | PDB=1c5k | SCENE= TolB/Tolb/1 }}<br /> TolB is a 44-kDa periplasmic protein partially associated with the outer membrane<ref name='Bouveret'>PMID: 7744736</ref>. It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which [[Pal]] and [[Colicin E9]] bind)<ref>PMID: 19696740</ref>. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.<br /> <br /> ==Function==<br /> The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of [[TolA]] in the inner membrane<ref>PMID: 19696740</ref>.<br /> <br /> TolB has been shown to be essential for the function of the [[Tol]] system in ''Escherichia coli''<ref>PMID: 19696740</ref> by generating an allosteric signal based on a conformational switch in the β-propeller region. TolB has also been shown to interact with the porins of Escherichia coli, in particular OmpF, OmpC, PhoE and LamB, but not OmpA or any of their denatured counterparts. It has been proposed that the whole Tol complex plays a role in this association, although "tol" mutants do not prevent this assembly completely therefore the Tol system may be involved kinetically, not directly<ref>PMID: 9393690</ref>.<br /> <br /> ==The TolB-Pal Complex==<br /> The TolB-[[Pal]] complex is involved in maintaining the outer membrane integrity. Upon binding, TolB and Pal undergo a conformational change , the result of which is crucial for further interactions with other proteins<ref name='Godlewska'>PMID: 19519769</ref>. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see [[Colicin]] for further information)<ref name='Bonsor'>PMID: 17375930</ref>.<br /> <br /> To study the interaction of TolB with Pal, two studies were carried out<ref name='Bouveret'>PMID 7744736</ref>: TolBBep (tagging TolB for immunoprecipitation), which allows the associated proteins to remain in contact with TolB, and ''in vivo'' cross-linking experiments with formaldehyde. Immunoprecipitation gave the result that Pal co-precipitates with TolBBep, while the cross-linking showed that in the present of Pal, the two products migrated close to each other, but in the absence of Pal, neither band was present, demonstrating an interaction between the two. These two experiments showed that TolB directly interacts with Pal, and that this interaction is responsible for maintaining the association of TolB with the membrane.<br /> <br /> <structure load='2w8b' size='300' align='right' caption='Interaction of TolB and Pal' (PDB entry [[2w8b]] | SCENE= TolB/Tolbpal/1 /><br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolB&diff=1234721 TolB 2011-04-25T16:23:58Z

<p>Laura McCauley: </p> <hr /> <div>==Structure==<br /> TolB is a 44-kDa periplasmic protein partially associated with the outer membrane<ref name='Bouveret'>PMID: 7744736</ref>. It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which [[Pal]] and [[Colicin E9]] bind)<ref>PMID: 19696740</ref>. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.<br /> <br /> {{STRUCTURE_1c5k | PDB=1c5k | SCENE= TolB/Tolb/1 }}<br /> ==Function==<br /> The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of [[TolA]] in the inner membrane<ref>PMID: 19696740</ref>.<br /> <br /> TolB has been shown to be essential for the function of the [[Tol]] system in ''Escherichia coli''<ref>PMID: 19696740</ref> by generating an allosteric signal based on a conformational switch in the β-propeller region. TolB has also been shown to interact with the porins of Escherichia coli, in particular OmpF, OmpC, PhoE and LamB, but not OmpA or any of their denatured counterparts. It has been proposed that the whole Tol complex plays a role in this association, although "tol" mutants do not prevent this assembly completely therefore the Tol system may be involved kinetically, not directly<ref>PMID: 9393690</ref>.<br /> <br /> ==The TolB-Pal Complex==<br /> The TolB-[[Pal]] complex is involved in maintaining the outer membrane integrity. Upon binding, TolB and Pal undergo a conformational change , the result of which is crucial for further interactions with other proteins<ref name='Godlewska'>PMID: 19519769</ref>. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see [[Colicin]] for further information)<ref name='Bonsor'>PMID: 17375930</ref>.<br /> <br /> To study the interaction of TolB with Pal, two studies were carried out<ref name='Bouveret'>PMID 7744736</ref>: TolBBep (tagging TolB for immunoprecipitation), which allows the associated proteins to remain in contact with TolB, and ''in vivo'' cross-linking experiments with formaldehyde. Immunoprecipitation gave the result that Pal co-precipitates with TolBBep, while the cross-linking showed that in the present of Pal, the two products migrated close to each other, but in the absence of Pal, neither band was present, demonstrating an interaction between the two. These two experiments showed that TolB directly interacts with Pal, and that this interaction is responsible for maintaining the association of TolB with the membrane.<br /> <br /> <structure load='2w8b' size='300' align='right' caption='Interaction of TolB and Pal' (PDB entry [[2w8b]] | SCENE= TolB/Tolbpal/1 /><br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Pal&diff=1234720 Pal 2011-04-25T16:20:58Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1oap | PDB=1oap | SCENE= Periplasmic_Domain_of_Pal/Palperiplasmicdomain/1 }}<br /> ==Structure==<br /> Pal is a lipoprotein which is anchored in the outer membrane with an approximate length of 173 amino acids in the precursor form. It contains a signal sequence including an LVAC motif, with the flexible, hydrophobic N-terminal tail binding to the inner leaflet of the outer membrane and anchoring it. During translocation, signal peptidase II cleaves the LVAC motif, and the localisation of Pal is dependent on the Lol protein system. Serine, the amino acid at #2 position in the mature protein is a localisation determinant for the position of Pal in the outer membrane<ref name='Godlewska'>PMID: 19519769</ref>. The periplasmic domain of Pal can be seen in the 3D structure 1OAP.<br /> <br /> ==Function==<br /> One of the roles of Pal is thought to be an anchor, linking the outer membrane to the peptidoglycan layer and offering support to this connection<ref>PMID: 16041489</ref>. It is also possible that Pal is involved in the translocation of subunits of the surface O-antigens, affecting its structure<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal is also thought to play a significant role in the process of pathogenesis. The protein is highly immunogenic, which also makes them suitable candidates for the production of vaccines<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> ==Interactions of Pal==<br /> Directed deletion mutagenesis was carried out to investigate the interactions of Pal with different components of the [[Tol]]-Pal system<ref>PMID: 14731286</ref>:<br /> #'''Pal and the peptidoglycan layer''' - specific residues in the C-terminal domain including S126, G128 and R146 are responsible for the modification of the electric charge, and may be responsible for affecting the peptidoglycan interaction.<br /> #'''Pal and TolB''' - ''see'' [[TolB]]<br /> #'''Pal and TolA''' - Pal may play a role in the stabilisation of [[TolA]], and that this interaction is essential if the cell integrity is to be maintained.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234719 YbgF 2011-04-25T16:20:07Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the [[Tol]] complex is recruited to the area of septation, or also during invagination<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of [[Colicin A]] into the cytoplasm<ref>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in [[TolA]], with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> Studies have shown that inactivation of the YbgF gene results in no discernible change in the activity of Tol<ref name="Walburger">PMID: 11994151</ref>. Therefore, replacing the protein with another would not rescue any lost function. Future research may look into comparison of different gram negative bacteria in order to determine if the function is conserved. One particular organism that is known to not have this domain conserved is ''Chlamydiae''<ref name='Krachler'>PMID: 20816983</ref>. Future research may look into the functioning of its Tol system, with a the possible addition of the YbgF domain to study what effect this might have.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234718 ExbD 2011-04-25T16:17:52Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|right|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> <br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found<ref name='Kampfenkel'>PMID: 1644779</ref>.<br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, therefore it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the [[TonB]] complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane<ref>PMID: 12193634</ref>. It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> The activity of ExbD can be affected with mutations of the single charged amino acid (here D25N) which lies close to the transmembrane region. This can also be said of the other transmembrane proteins ExbB, TolQ and TolR.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234717 ExbD 2011-04-25T16:17:18Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|right|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> <br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found<ref name='Kampfenkel'>PMID: 1644779</ref>.<br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, therefore it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the [[TonB]] complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane<ref>PMID: 12193634</ref>. It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with [[ExbB]], suggesting an evolutionary link between the two complexes<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> The activity of ExbD can be affected with mutations of the single charged amino acid (here D25N) which lies close to the transmembrane region. This can also be said of the other transmembrane proteins ExbB, TolQ and TolR.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbB&diff=1234716 ExbB 2011-04-25T16:16:03Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbB.jpg|300px|right|thumb| The Structure of ExbB<ref name='Kampfenkel'>PMID: 8449962</ref>]]<br /> <br /> == Structure==<br /> ExbB consists of three transmembrane domains (spanning from residues 16-39, 128-155 and 162-194), with two large portions of the protein representing the majority of the protein in the cytoplasm and two smaller portions in the periplasm<ref name='Kampfenkel'>PMID: 8449962</ref>.<br /> <br /> ExbB can exist in the [[TonB]] system either in a complex with [[ExbD]] (to a ratio of 3.5:1) or on its own (where no ExbD is present), which has been suggested to play a part in the diverse roles of TonB<ref name='Held'>PMID: 12193634</ref>.<br /> <br /> ExbB has a similar sequence and physiological structure to [[TolQ]] and is therefore thought to be evolutionarily linked<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> ==Function==<br /> ExbB is essential for TonB-dependent energy transduction as the absence of ExbB prevents TonB responding to the proton motive force, as well as the change of the high-affinity association of TonB for the outer membrane to the cytoplasmic membrane<ref name='Held'>PMID: 12193634</ref>.<br /> <br /> Loss of ExbB function can be partially replaced by TolQ and vice versa - reduced activities of either of these proteins via a mutant form can be reversed by introducing double mutants<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234715 ExbD 2011-04-25T16:14:17Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|right|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> <br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found<ref name='Kampfenkel'>PMID: 1644779</ref>.<br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the TonB complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane<ref>PMID: 12193634</ref>. It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> The activity of ExbD can be affected with mutations of the single charged amino acid (here D25N) which lies close to the transmembrane region. This can also be said of the other transmembrane proteins ExbB, TolQ and TolR.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234714 ExbD 2011-04-25T16:07:29Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|right|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> <br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found.<ref name='Kampfenkel'>PMID: 1644779</ref><br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the TonB complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane. <ref>PMID: 12193634</ref> It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbD&diff=1234713 ExbD 2011-04-25T16:06:59Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbD.jpg|300px|right|thumb| The Structure of ExbD<ref name='Kampfenkel'>PMID: 1644779</ref>]]<br /> <br /> ==Structure==<br /> ExbD has a single transmembrane domain, with residues 1 to 22 on the cytoplasmic side and 44 to 141 in the periplasm. Residues 23 to 43 are within the cytoplasmic membrane and it is in this region, from residues 18 to 43, that the only hydrophobic residues in ExbD can be found.<ref name='Kampfenkel'>PMID: 1644779</ref><br /> <br /> ExbD has been shown to be approximately 25% identical and 70% similar to the [[TolR]] sequence<ref name='Kampfenkel'>PMID: 1644779</ref>, it can be assumed that these two proteins will have a similar arrangement of their sequences.<br /> <br /> ==Function== <br /> Like TolR, ExbD is also involved in the uptake of colicins across the outer membrane of Escherichia coli, but unlike TolR which transports group A colicins, ExbD transports group B colicins. It is also involved in the transferring of vitamin B<sub>12</sub> and ferric siderophores using energy-coupled transport.<br /> <br /> ExbD is present in cells only in a complex with [[ExbB]], where is affects the functioning of the TonB complex both in how it responds to the proton motive force as well as its affinity with either the cytoplasmic or outer membrane. <ref>PMID: 12193634</ref> It has also been shown that TolR can replace the function of an ExbD mutant just as [[TolQ]] can with ExbB, suggesting an evolutionary link between the two complexes.<br /> <br /> {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }}<br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TonB&diff=1234712 TonB 2011-04-25T16:05:40Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1xx3 | PDB=1xx3 | SCENE= TonB/Ctdtonb/1 }}<br /> <br /> ==Structure==<br /> The structure to the right (1XX3) shows the structure of TonB. The protein spans the periplasm <ref>PMID: 16741125</ref>, with the C-terminus of TonB spanning from residues ~150 to 239<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ==Function==<br /> TonB is involved in the uptake of iron as a component of the TonB/[[ExbB]]/[[ExbD]] complex of the [[Ton]] system. It's activity is determined by the presence of ExbB and ExbD<ref name='Kampfenkel'>PMID: 8449962</ref>. The C-terminus of TonB interacts with outer membrane transporters, known as TonB-dependent outer membrane transporters (TBDTs)<ref name=Wiener'>PMID: 16039843</ref>, allowing the translocation of biochemical molecules between the inner and outer membrane<ref name='Postle'>PMID: 21179522</ref>.<br /> <br /> ===Interaction with ExbB/ExbD===<br /> TonB and ExbD bind to ExbB in a protein complex that prevents the degradation of the TonB protein. TonB and ExbD are anchored to the cytoplasmic membrane via their N-terminal hydrophobic sequences, with the rest of the protein complex extending into the periplasmic space, allowing for interaction with outer membrane proteins.<ref name='Kampfenkel'>PMID: 8449962</ref><br /> <br /> ===BtuB-TonB Complex===<br /> As shown in the 3D structure to the right (2GSK), TonB complexes with [[BtuB]] in order to aid the transport of nutrients such as cobalamins<ref name='Cadieux'>PMID 11029413</ref> across the outer membrane by incorporating the proton-motive force into the outer membrane.<ref name='Shultis'>PMID: 16741124</ref> TonB attaches to BtuB on the periplasmic side of the 614 amino acid BtuB protein<ref name='Shultis'> PMID: 16741124</ref>.<br /> <br /> {{STRUCTURE_2gsk | PDB=2gsk | SCENE= BtuB-TonB_Complex/Btubtonbcomplex/1 }}<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolQ&diff=1234711 TolQ 2011-04-25T16:04:21Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:TolQ.jpg|600px|right|thumb| The TolQ Membrane-spanning domains <ref>PMID: 8662905</ref>]]<br /> <br /> ==Structure==<br /> TolQ is a polytopic protein located in the inner (cytoplasmic) membrane, containing approximately 230 amino acids. There are three membrane spanning segments in TolQ with each segment containing an α-helix<ref>PMID: 7853390</ref>. TM1 is connected to TM2 via a large cytoplasmic loop, with the N-terminal ending in the periplasm. This topology is also found in [[ExbB]], which can be explained by the similar sequence shared by both proteins<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> It has been shown that 4 to 6 TolQ molecules associate in the TolQRA complex, and that they form multimers which interact with the transmembrane helices (TMH) of TolQ, TolR and TolA<ref> PMID: 21285349</ref>. The multimers are formed by the three TMHs of TolQ, the last of which undergo a conformational change to form a hairpin, while the first TMH forms an intermolecular interaction<ref name='Vianney'> PMID:8300535</ref>.<br /> <br /> ==Function==<br /> TolQ plays an important role in the maintenance of the bacterial envelope integrity as well as the import of filamentous bacteriophage and group A colicins<ref name='Vianney'> PMID:8300535</ref>.<br /> <br /> Loss of TolQ function can be partially replaced by ExbB and vice versa - reduced activities of either of these proteins via a mutant form can be reversed by introducing double mutants<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=ExbB&diff=1234710 ExbB 2011-04-25T16:03:30Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:ExbB.jpg|300px|right|thumb| The Structure of ExbB<ref name='Kampfenkel'>PMID: 8449962</ref>]]<br /> <br /> == Structure==<br /> ExbB consists of three transmembrane domains (spanning from residues 16-39, 128-155 and 162-194), with two large portions of the protein representing the majority of the protein in the cytoplasm and two smaller portions in the periplasm.<ref name='Kampfenkel'>PMID: 8449962</ref><br /> <br /> ExbB can exist in the TonB system either in a complex with [[ExbD]] (to a ratio of 3.5:1) or on its own (where no ExbD is present), which has been suggested to play a part in the diverse roles of TonB.<ref name='Held'>PMID: 12193634</ref><br /> <br /> ExbB has a similar sequence and physiological structure to [[TolQ]] and is therefore thought to be evolutionarily linked<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> ==Function==<br /> ExbB is essential for TonB-dependent energy transduction as the absence of ExbB prevents TonB responding to the proton motive force, as well as the change of the high-affinity association of TonB for the outer membrane to the cytoplasmic membrane<ref name='Held'>PMID: 12193634</ref>.<br /> <br /> Loss of ExbB function can be partially replaced by TolQ and vice versa - reduced activities of either of these proteins via a mutant form can be reversed by introducing double mutants<ref name='Braun'>PMID: 15205446</ref>.<br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Pal&diff=1234705 Pal 2011-04-25T15:36:21Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1oap | PDB=1oap | SCENE= Periplasmic_Domain_of_Pal/Palperiplasmicdomain/1 }}<br /> ==Structure==<br /> Pal is a lipoprotein which is anchored in the outer membrane with an approximate length of 173 amino acids in the precursor form. It contains a signal sequence including an LVAC motif, with the flexible, hydrophobic N-terminal tail binding to the inner leaflet of the outer membrane and anchoring it. During translocation, signal peptidase II cleaves the LVAC motif, and the localisation of Pal is dependent on the Lol protein system. Serine, the amino acid at #2 position in the mature protein is a localisation determinant for the position of Pal in the outer membrane<ref name='Godlewska'>PMID: 19519769</ref>. The periplasmic domain of Pal can be seen in the 3D structure 1OAP.<br /> <br /> ==Function==<br /> One of the roles of Pal is thought to be an anchor, linking the outer membrane to the peptidoglycan layer and offering support to this connection<ref>PMID: 16041489</ref>. It is also possible that Pal is involved in the translocation of subunits of the surface O-antigens, affecting its structure<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal is also thought to play a significant role in the process of pathogenesis. The protein is highly immunogenic, which also makes them suitable candidates for the production of vaccines<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> ==Interactions of Pal==<br /> Directed deletion mutagenesis was carried out to investigate the interactions of Pal with different components of the Tol-Pal system<ref>PMID: 14731286</ref>:<br /> #'''Pal and the peptidoglycan layer''' - specific residues in the C-terminal domain including S126, G128 and R146 are responsible for the modification of the electric charge, and may be responsible for affecting the peptidoglycan interaction.<br /> #'''Pal and TolB''' - ''see'' [[TolB]]<br /> #'''Pal and TolA''' - Pal may play a role in the stabilisation of [[TolA]], and that this interaction is essential if the cell integrity is to be maintained.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolA&diff=1234703 TolA 2011-04-25T15:32:22Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1s62 | PDB=1s62 | SCENE= TolA/Ctdtola/1 }}<br /> <br /> ==Structure==<br /> TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II.<ref name='Sharyn'>PMID: 8416897</ref> <br /> <br /> ===C-terminal Domain===<br /> The C-terminal domain of TolA is directly involved with the N-terminal of both [[Colicin]] and the phage minor coat gene 3 protein. <ref>PMID: 15701516</ref><br /> <br /> ===Comparison with TonB===<br /> TolA and [[TonB]] have been shown to have a common evolutionary origin: although the two proteins can undergo domain swapping, this is difficult to achieve. Through sedimentation experiments, it has been shown that TonB is able to remain as a monomer and form a TolA-like fold, but there would be an exposed β-ribbon which would need to undergo extensive conformational changes. TolA does have the potential to dimerise, but it is highly unlike that it will do so. Nevertheless, the structural similarities between these two proteins clearly indicates an evolutionary relationship, even if the functional properties have divulged<ref name='Witty'> PMID: 12169623</ref>.<br /> <br /> ==Function==<br /> Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them.<ref name='Sharyn'>PMID: 8416897</ref><br /> <br /> TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see [[Colicin]]) and the DNA of filamentous bacteriophages<ref name='Deprez'>PMID: 15701516</ref>, and has also been shown to be involved in the bacterial sensitivity to these groups<ref>PMID: 7853390</ref>, in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)<ref name='Schendel">PMID: 9171417</ref>.<br /> <br /> ===TolA and Colicin Uptake===<br /> Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein. <ref>PMID: 15701516</ref><br /> <br /> TolA interacts with different group A colicins in different ways<ref name='Schendel">PMID: 9171417</ref>:<br /> * [[Colicin E1]] requires different structural features of TolA to be transported than the other group A colicins, including E3, N and A. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins<br /> * The other colicins require additional receptors in order to bind initially to the outer membrane<br /> *Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Pal&diff=1234700 Pal 2011-04-25T15:20:30Z

<p>Laura McCauley: </p> <hr /> <div>==Structure==<br /> Pal is a lipoprotein which is anchored in the outer membrane with an approximate length of 173 amino acids in the precursor form. It contains a signal sequence including an LVAC motif, with the flexible, hydrophobic N-terminal tail binding to the inner leaflet of the outer membrane and anchoring it. During translocation, signal peptidase II cleaves the LVAC motif, and the localisation of Pal is dependent on the Lol protein system. Serine, the amino acid at #2 position in the mature protein is a localisation determinant for the position of Pal in the outer membrane<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal forms a complex with TolB (''see'' [[TolB]]).<br /> <br /> {{STRUCTURE_1oap | PDB=1oap | SCENE= Periplasmic_Domain_of_Pal/Palperiplasmicdomain/1 }}<br /> <br /> ==Function==<br /> One of the roles of Pal is thought to be an anchor, linking the outer membrane to the peptidoglycan layer and offering support to this connection<ref>PMID: 16041489</ref>. It is also possible that Pal is involved in the translocation of subunits of the surface O-antigens, affecting its structure<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal is also thought to play a significant role in the process of pathogenesis. The protein is highly immunogenic, which also makes them suitable candidates for the production of vaccines<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=TolB&diff=1234699 TolB 2011-04-25T15:19:08Z

<p>Laura McCauley: </p> <hr /> <div>{{STRUCTURE_1c5k | PDB=1c5k | SCENE= TolB/Tolb/1 }}<br /> TolB has been shown to be essential for the function of the [[Tol]] system in ''Escherichia coli''<ref>PMID: 19696740</ref> by generating an allosteric signal based on a conformational switch in the β-propeller region.<br /> <br /> ==Structure==<br /> TolB is a 44-kDa periplasmic protein partially associated with the outer membrane.<ref name='Bouveret'>PMID: 7744736</ref> It has two domains: an N-terminal α/β domain and a C-terminal six-bladed β-propeller (to which [[Pal]] and [[Colicin E9]] bind) <ref>PMID: 19696740</ref>. The β-propeller has a latching or ‘Velco’ strand which joins the first and last of the six blades, and is positioned in the domain-domain interface. When Pal binds to the C-terminus of TolB, the latching strand moves away from the interface and carries with it a proline residue. The movement of the latching strand opens up a canyon that would normally be buried between the N- and C-terminal domains of TolB. This canyon can now be used as a binding site for the N-terminal of TolB, which forms a helical half-turn and a β-sheet against the canyon.<br /> <br /> TolB forms a complex with Pal (''see below'') which plays a role in maintaining the integrity of the outer membrane.<br /> <br /> ==Function==<br /> The distal N-terminal 12 residues of TolB has two conformational states which are governed by protein-protein interactions with the β -propeller and results in the binding of TolA in the inner membrane.<ref>PMID: 19696740</ref><br /> <br /> TolB has been shown to interact with the porins of Escherichia coli, in particular OmpF, OmpC, PhoE and LamB, but not OmpA or any of their denatured counterparts. It has been proposed that the whole Tol complex plays a role in this association, although "tol" mutants do not prevent this assembly completely therefore the Tol system may be involved kinetically, not directly.<ref>PMID: 9393690</ref><br /> <br /> ==The TolB-Pal Complex==<br /> The TolB-[[Pal]] complex is involved in maintaining the outer membrane integrity. Upon binding, TolB and Pal undergo a conformational change , the result of which is crucial for further interactions with other proteins<ref name='Godlewska'>PMID: 19519769</ref>. This complex is parasitised by protein antibiotics and disrupted in order to trigger the translocation of the toxin across the outer membrane (see [[Colicin]] for further information).<ref name='Bonsor'>PMID: 17375930</ref><br /> <br /> To study the interaction of TolB with Pal, two studies were carried out<ref name='Bouveret'>PMID 7744736</ref>: TolBBep (tagging TolB for immunoprecipitation), which allows the associated proteins to remain in contact with TolB, and ''in vivo'' cross-linking experiments with formaldehyde. Immunoprecipitation gave the result that Pal co-precipitates with TolBBep, while the cross-linking showed that in the present of Pal, the two products migrated close to each other, but in the absence of Pal, neither band was present, demonstrating an interaction between the two. These two experiments showed that TolB directly interacts with Pal, and that this interaction is responsible for maintaining the association of TolB with the membrane.<br /> <br /> <structure load='2w8b' size='300' align='right' caption='Interaction of TolB and Pal' (PDB entry [[2w8b]] | SCENE= TolB/Tolbpal/1 /><br /> <br /> == References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Pal&diff=1234698 Pal 2011-04-25T15:16:23Z

<p>Laura McCauley: </p> <hr /> <div>==Structure==<br /> Pal is a lipoprotein which is anchored in the outer membrane with an approximate length of 173 amino acids in the precursor form. It contains a signal sequence including an LVAC motif, with the flexible, hydrophobic N-terminal tail binding to the inner leaflet of the outer membrane and anchoring it. During translocation, signal peptidase II cleaves the LVAC motif, and the localisation of Pal is dependent on the Lol protein system. Serine, the amino acid at #2 position in the mature protein is a localisation determinant for the position of Pal in the outer membrane<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal forms a complex with TolB (''see'' [[TolB]]).<br /> <br /> ===Periplasmic Domain of Pal===<br /> {{STRUCTURE_1oap | PDB=1oap | SCENE= Periplasmic_Domain_of_Pal/Palperiplasmicdomain/1 }}<br /> <br /> ==Function==<br /> One of the roles of Pal is thought to be an anchor, linking the outer membrane to the peptidoglycan layer and offering support to this connection<ref>PMID: 16041489</ref>. It is also possible that Pal is involved in the translocation of subunits of the surface O-antigens, affecting its structure<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> Pal is also thought to play a significant role in the process of pathogenesis. The protein is highly immunogenic, which also makes them suitable candidates for the production of vaccines<ref name='Godlewska'>PMID: 19519769</ref>.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=Pal&diff=1234694 Pal 2011-04-25T14:55:36Z

<p>Laura McCauley: </p> <hr /> <div>==Structure==<br /> Pal is a lipoprotein which is anchored in the outer membrane. Synthesised as a precursor of 173 amino acids, it contains a signal sequence including an LVAC motif, with the flexible N-terminal tail binding to the inner leaflet of the outer membrane<ref>PMID: 19519769</ref><br /> <br /> Pal forms a complex with TolB (''see'' [[TolB]])<br /> <br /> ===Periplasmic Domain of Pal===<br /> {{STRUCTURE_1oap | PDB=1oap | SCENE= Periplasmic_Domain_of_Pal/Palperiplasmicdomain/1 }}<br /> <br /> ==Function==<br /> During translocation, signal peptidase II cleaves the LVAC motif, and the localisation of Pal is dependent on the Lol protein system<ref>.<br /> PMID: 19519769</ref><br /> <br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234680 YbgF 2011-04-25T12:34:04Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the Tol complex is recruited to the area of septation, or also during invagination<ref name='Krachler'>PMID: 20816983</ref.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of colicin A into the cytoplasm<ref>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in TolA, with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> Studies have shown that inactivation of the YbgF gene results in no discernible change in the activity of Tol<ref name="Walburger">PMID: 11994151</ref>. Therefore, replacing the protein with another would not rescue any lost function. Future research may look into comparison of different gram negative bacteria in order to determine if the function is conserved. One particular organism that is known to not have this domain conserved is ''Chlamydiae''<ref name='Krachler'>PMID: 20816983</ref>.. Future research may look into the functioning of its Tol system, with a the possible addition of the YbgF domain to study what effect this might have.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234679 YbgF 2011-04-25T12:28:46Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the Tol complex is recruited to the area of septation, or also during invagination<ref name='Krachler'>PMID: 20816983</ref.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of colicin A into the cytoplasm<ref>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in TolA, with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==References==<br /> </references></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234678 YbgF 2011-04-25T12:26:19Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the Tol complex is recruited to the area of septation, or also during invagination<ref name='Krachler'>PMID: 20816983</ref.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of colicin A into the cytoplasm<ref>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in TolA, with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Krachler'>PMID: 20816983</ref.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234677 YbgF 2011-04-25T12:24:43Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> ==Function==<br /> Although YbgF is conserved in most gram-negative organisms, the exact function of this protein is still unknown. It may be involved in the late stages of cell division when the Tol complex is recruited to the area of septation, or also during invagination<ref name='Gerding'>PMID: 17233825</ref>.<br /> <br /> It is known that YbgF interacts with the C-terminal domain of TolA during the import of colicin A into the cytoplasm<ref>PMID: 11994151</ref>. The TPR domain in YgbF has been shown to bind to domain II in TolA, with the binding site located between residues 280-313<ref name='Gerding'>PMID: 17233825</ref>. The NTD is not directly involved with the binding to TolA, but is important for the transition of YbgF in its oligomeric state when binding to TolA. This may be due to the NTD restricting the formation of the trimer state, allowing the TPR to bind with TolA<ref name='Gerding'>PMID: 17233825</ref>.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley https://proteopedia.org/index.php?title=YbgF&diff=1234676 YbgF 2011-04-25T12:08:56Z

<p>Laura McCauley: </p> <hr /> <div>[[Image:YbgF.jpg|300px|left|thumb| The Structure of YbgF<ref name='Gerding'>PMID: 17233825</ref> ]]<br /> {{STRUCTURE_2xev | PDB=2xev | SCENE= YbgF/Ntermygbf/1 }}<br /> {{STRUCTURE_2wz7 | PDB=2wz7 | SCENE= YbgF/Ybgf/1 }}<br /> ==Structure==<br /> YbgF is a periplasmic protein with an N-terminal coiled coil domain (NTD) and a C-terminal tetratricopeptide domain (TPR), both of which are autonomous<ref name='Gerding'>PMID: 17233825</ref>. As seen in the 3D structure 2WZ7, the NTD forms an elongated trimer which is connected via a flexible linker to the TPR trimer, as seen in 2XEV. This connection can be cleaved by proteases<ref name='Krachler'>PMID: 20816983</ref>.<br /> <br /> <br /> ==Function==<br /> YbgF is a periplasmic protein which interacts with the C-terminal domain of TolA (TolAIII) during the import of colicin A into the cytoplasm<ref>PMID: 11994151</ref>.<br /> <br /> ==References==<br /> <references/></div>

Laura McCauley