Stabilization of G domain conformations in the tRNA-modifying MnmE-GidA complex observed with double electron electron resonance spectroscopy.
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.
Böhme
Sabine
S
Department of Physics, University of Osnabrück, Barbarastrasse 7, D-49076 Osnabrück, Germany.
Meyer
Simon
S
Krüger
André
A
Steinhoff
Heinz-Jürgen
HJ
Wittinghofer
Alfred
A
Klare
Johann P
JP
D001426:Bacterial Proteins / Q000737:chemistry; D019281:Dimerization; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008956:Models, Chemical; D008968:Molecular Conformation; D009154:Mutation; D019875:One-Carbon Group Transferases; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000737:chemistry*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012343:RNA, Transfer; C546582:MnmG protein, E coli; D019875:One-Carbon Group Transferases; D020558:GTP Phosphohydrolases; C492932:MnmE protein, E coli