2gj9
From Proteopedia
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'''Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and Rb+''' | '''Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and Rb+''' | ||
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[[Category: Scrima, A.]] | [[Category: Scrima, A.]] | ||
[[Category: Wittinghofer, A.]] | [[Category: Wittinghofer, A.]] | ||
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| - | [[Category: | + | [[Category: G-domain dimer]] |
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Revision as of 02:10, 4 May 2008
Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and Rb+
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.
About this Structure
2GJ9 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Dimerisation-dependent GTPase reaction of MnmE: how potassium acts as GTPase-activating element., Scrima A, Wittinghofer A, EMBO J. 2006 Jun 21;25(12):2940-51. Epub 2006 Jun 8. PMID:16763562 Page seeded by OCA on Sun May 4 05:10:15 2008
