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| {{STRUCTURE_2gja| PDB=2gja | SCENE= }} | | {{STRUCTURE_2gja| PDB=2gja | SCENE= }} |
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| '''Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and NH4+'''
| | ===Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and NH4+=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16763562}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16763562 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16763562}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Alpha-beta-sandwich]] | | [[Category: Alpha-beta-sandwich]] |
| [[Category: G-domain dimer]] | | [[Category: G-domain dimer]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 05:10:18 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:32:52 2008'' |
