Stabilization of G Domain Conformations in the tRNA-modifying MnmE-GidA Complex Observed with Double Electron Electron Resonance Spectroscopy

Autor(en): Boehme, Sabine
Meyer, Simon
Krueger, Andre
Steinhoff, Heinz-Juergen 
Wittinghofer, Alfred
Klare, Johann P.
Stichwörter: Biochemistry & Molecular Biology; BIOMACROMOLECULES; CODES; EXPRESSION; GENE; GTP-BINDING PROTEIN; INSIGHTS; MTO1; MUTANTS; POSITION
Erscheinungsdatum: 2010
Herausgeber: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Journal: JOURNAL OF BIOLOGICAL CHEMISTRY
Volumen: 285
Ausgabe: 22
Startseite: 16991
Seitenende: 17000
Zusammenfassung: 
MnmE is a GTP-binding protein conserved between bacteria and eukarya. It is a dimeric three-domain protein where the two G domains have to approach each other for activation of the potassium-stimulated GTPase reaction. Together with GidA, in a heterotetrameric alpha(2)beta(2) complex, it is involved in the modification of the wobble uridine base U34 of the first anticodon position of particular tRNAs. Here we show, using various spin-labeled MnmE mutants and EPR spectroscopy, that GidA binding induces large conformational and dynamic changes in MnmE. It stimulates the GTPase reaction by stabilizing the GTP-bound conformation in a potassium-independent manner. Surprisingly, GidA binding influences not only the GTP-but also the GDP-bound conformation. Thus GidA is a new type of regulator for a G protein activated by dimerization.
ISSN: 00219258
DOI: 10.1074/jbc.M109.096131

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