tRNA dynamics on the ribosome during translation.
Using single-molecule fluorescence spectroscopy, time-resolved conformational changes between fluorescently labeled tRNA have been characterized within surface-immobilized ribosomes proceeding through a complete cycle of translation elongation. Fluorescence resonance energy transfer was used to observe aminoacyl-tRNA (aa-tRNA) stably accommodating into the aminoacyl site (A site) of the ribosome via a multistep, elongation factor-Tu dependent process. Subsequently, tRNA molecules, bound at the peptidyl site and A site, fluctuate between two configurations assigned as classical and hybrid states. The lifetime of classical and hybrid states, measured for complexes carrying aa-tRNA and peptidyl-tRNA at the A site, shows that peptide bond formation decreases the lifetime of the classical-state tRNA configuration by approximately 6-fold. These data suggest that the growing peptide chain plays a role in modulating fluctuations between hybrid and classical states. Single-molecule fluorescence resonance energy transfer was also used to observe aa-tRNA accommodation coupled with elongation factor G-mediated translocation. Dynamic rearrangements in tRNA configuration are also observed subsequent to the translocation reaction. This work underscores the importance of dynamics in ribosome function and demonstrates single-particle enzymology in a system of more than two components.
Blanchard
Scott C
SC
Department of Physics and Applied Physics, Stanford University, Stanford, CA 94305-4060, USA.
Kim
Harold D
HD
Gonzalez
Ruben L
RL
Puglisi
Joseph D
JD
Chu
Steven
S
D031541:Fluorescence Resonance Energy Transfer; D008856:Microscopy, Fluorescence; D014176:Protein Biosynthesis / Q000502:physiology*; D012343:RNA, Transfer / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D013997:Time Factors
D012343:RNA, Transfer