2gja: Difference between revisions

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[[Image:2gja.gif|left|200px]]<br /><applet load="2gja" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:2gja.gif|left|200px]]<br /><applet load="2gja" size="350" color="white" frame="true" align="right" spinBox="true"

caption="2gja, resolution 1.85Å" />

'''Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and NH4+'''<br />

==Overview==

MnmE, a Guanine nucleotide-binding protein conserved between bacteria and, man, is involved in the modification of tRNAs. Here we provide biochemical, and X-ray structural evidence for a new GTP-hydrolysis mechanism, where, the G-domains of MnmE dimerise in a potassium-dependent manner and induce, GTP hydrolysis. The structure in the presence of GDP-AlFx and potassium, shows how juxtaposition of the subunits induces a conformational change, around the nucleotide which reorients the catalytic machinery. A critical, glutamate is positioned such as to stabilise or activate the attacking, water. Potassium provides a positive charge into the catalytic site in a, position analogous to the arginine finger in the Ras-RasGAP system., Mutational studies show that potassium-dependent dimerisation and GTP, hydrolysis can be uncoupled and that interaction between the G-domains is, a prerequisite for subsequent phosphoryl transfer. We propose a model for, the juxtaposition of G-domains in the full-length protein and how it, induces conformational changes in the putative tRNA-modification centre.

MnmE, a Guanine nucleotide-binding protein conserved between bacteria and man, is involved in the modification of tRNAs. Here we provide biochemical and X-ray structural evidence for a new GTP-hydrolysis mechanism, where the G-domains of MnmE dimerise in a potassium-dependent manner and induce GTP hydrolysis. The structure in the presence of GDP-AlFx and potassium shows how juxtaposition of the subunits induces a conformational change around the nucleotide which reorients the catalytic machinery. A critical glutamate is positioned such as to stabilise or activate the attacking water. Potassium provides a positive charge into the catalytic site in a position analogous to the arginine finger in the Ras-RasGAP system. Mutational studies show that potassium-dependent dimerisation and GTP hydrolysis can be uncoupled and that interaction between the G-domains is a prerequisite for subsequent phosphoryl transfer. We propose a model for the juxtaposition of G-domains in the full-length protein and how it induces conformational changes in the putative tRNA-modification centre.

==About this Structure==

2GJA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with ALF, MG, NH4 and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=2GJA OCA].

2GJA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=ALF:'>ALF</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=NH4:'>NH4</scene> and <scene name='pdbligand=GDP:'>GDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GJA OCA].

==Reference==

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[[Category: g-domain dimer]]

''Page seeded by [http://~~ispc~~.weizmann.ac.il/oca OCA ] on ~~Wed Nov~~ 21 11:14:~~26 2007~~''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:32:16 2008''

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@@ Line 1: / Line 1: @@
-[[Image:2gja.gif|left|200px]]<br /><applet load="2gja" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:2gja.gif|left|200px]]<br /><applet load="2gja" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="2gja, resolution 1.85&Aring;" />
 '''Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and NH4+'''<br />
 ==Overview==
-MnmE, a Guanine nucleotide-binding protein conserved between bacteria and, man, is involved in the modification of tRNAs. Here we provide biochemical, and X-ray structural evidence for a new GTP-hydrolysis mechanism, where, the G-domains of MnmE dimerise in a potassium-dependent manner and induce, GTP hydrolysis. The structure in the presence of GDP-AlFx and potassium, shows how juxtaposition of the subunits induces a conformational change, around the nucleotide which reorients the catalytic machinery. A critical, glutamate is positioned such as to stabilise or activate the attacking, water. Potassium provides a positive charge into the catalytic site in a, position analogous to the arginine finger in the Ras-RasGAP system., Mutational studies show that potassium-dependent dimerisation and GTP, hydrolysis can be uncoupled and that interaction between the G-domains is, a prerequisite for subsequent phosphoryl transfer. We propose a model for, the juxtaposition of G-domains in the full-length protein and how it, induces conformational changes in the putative tRNA-modification centre.
+MnmE, a Guanine nucleotide-binding protein conserved between bacteria and man, is involved in the modification of tRNAs. Here we provide biochemical and X-ray structural evidence for a new GTP-hydrolysis mechanism, where the G-domains of MnmE dimerise in a potassium-dependent manner and induce GTP hydrolysis. The structure in the presence of GDP-AlFx and potassium shows how juxtaposition of the subunits induces a conformational change around the nucleotide which reorients the catalytic machinery. A critical glutamate is positioned such as to stabilise or activate the attacking water. Potassium provides a positive charge into the catalytic site in a position analogous to the arginine finger in the Ras-RasGAP system. Mutational studies show that potassium-dependent dimerisation and GTP hydrolysis can be uncoupled and that interaction between the G-domains is a prerequisite for subsequent phosphoryl transfer. We propose a model for the juxtaposition of G-domains in the full-length protein and how it induces conformational changes in the putative tRNA-modification centre.
 ==About this Structure==
-GJA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with ALF, MG, NH4 and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2GJA OCA].
+GJA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=ALF:'>ALF</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=NH4:'>NH4</scene> and <scene name='pdbligand=GDP:'>GDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GJA OCA].
 ==Reference==
@@ Line 22: / Line 22: @@
 [[Category: g-domain dimer]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 11:14:26 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:32:16 2008''