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2gj8
From Proteopedia
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Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and K+
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
2GJ8 is a Single protein structure of sequence from Escherichia coli with ALF, MG, K, SE and GDP as ligands. 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 Wed Nov 21 11:14:20 2007
Categories: Escherichia coli | Single protein | Scrima, A. | Wittinghofer, A. | ALF | GDP | K | MG | SE | Alpha-beta-sandwich | G-domain dimer
