Correlated conformational events in EF-G and the ribosome regulate translocation.
In bacteria, the translocation of tRNA and mRNA with respect to the ribosome is catalyzed by the conserved GTPase elongation factor-G (EF-G). To probe the rate-determining features in this process, we imaged EF-G-catalyzed translocation from two unique structural perspectives using single-molecule fluorescence resonance energy transfer. The data reveal that the rate at which the ribosome spontaneously achieves a transient, 'unlocked' state is closely correlated with the rate at which the tRNA-like domain IV-V element of EF-G engages the A site. After these structural transitions, translocation occurs comparatively fast, suggesting that conformational processes intrinsic to the ribosome determine the rate of translocation. Experiments conducted in the presence of non-hydrolyzable GTP analogs and specific antibiotics further reveal that allosterically linked conformational events in EF-G and the ribosome mediate rapid, directional substrate movement and EF-G release.
Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, USA.
James B
JB
Munro
Michael R
MR
Wasserman
Roger B
RB
Altman
Leyi
L
Wang
Scott C
SC
Blanchard
D004926:Escherichia coli / Q000235:genetics*; D031541:Fluorescence Resonance Energy Transfer; D007700:Kinetics; D008957:Models, Genetic; D020653:Peptide Elongation Factor G / Q000737:chemistry* / Q000502:physiology; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000502:physiology
D020653:Peptide Elongation Factor G; D012343:RNA, Transfer