2GJA

Structure of the MnmE G-domain in complex with GDP*AlF4-, Mg2+ and NH4+

Summary for 2GJA

• Entry DOI: 10.2210/pdb2gja/pdb
• Related: 1RFL 1XZP 1XZQ 2GJ8 2GJ9
• Descriptor: tRNA modification GTPase trmE, TETRAFLUOROALUMINATE ION, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: g-domain dimer, alpha-beta-sandwich, hydrolase
• Biological source: Escherichia coli BL21(DE3)
• Cellular location: Cytoplasm: P25522
• Total number of polymer chains: 2
• Total formula weight: 38417.28

Authors

Scrima, A.,Wittinghofer, A. (deposition date: 2006-03-30, release date: 2006-07-04, Last modification date: 2024-02-14)

Primary citation

Scrima, A.,Wittinghofer, A.
Dimerisation-dependent GTPase reaction of MnmE: how potassium acts as GTPase-activating element.
Embo J., 25:2940-2951, 2006

PubMed Abstract: 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.

PubMed: 16763562
DOI: 10.1038/sj.emboj.7601171

Experimental method

X-RAY DIFFRACTION (1.85 Å)