ExbD: Difference between revisions
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==Structure== | ==Structure== | ||
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 | 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>. | ||
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. | 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. | ||
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==Function== | ==Function== | ||
{{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }} | {{STRUCTURE_2pfu | PDB=2pfu | SCENE= Periplasmic_Domain_of_ExbD/Periplasmicdomainexbd/1 }} | ||
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>. | |||
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. | 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. | ||
ExbD | 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. | ||
== References== | == References== | ||
<references/> | <references/> | ||
