title: Coupling of ribosomal L1 stalk and tRNA dynamics during translation elongation.
abstract: By using single-molecule fluorescence resonance energy transfer (smFRET), we observe the real-time dynamic coupling between the ribosome, labeled at the L1 stalk, and transfer RNA (tRNA). We find that an interaction between the ribosomal L1 stalk and the newly deacylated tRNA is established spontaneously upon peptide bond formation; this event involves coupled movements of the L1 stalk and tRNAs as well as ratcheting of the ribosome. In the absence of elongation factor G, the entire pretranslocation ribosome fluctuates between just two states: a nonratcheted state, with tRNAs in their classical configuration and no L1 stalk-tRNA interaction, and a ratcheted state, with tRNAs in an intermediate hybrid configuration and a direct L1 stalk-tRNA interaction. We demonstrate that binding of EF-G shifts the equilibrium toward the ratcheted state. Real-time smFRET experiments reveal that the L1 stalk-tRNA interaction persists throughout the translocation reaction, suggesting that the L1 stalk acts to direct tRNA movements during translocation.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Fei
authors.forename: Pallav
authors.initials: P
authors.lastname: Kosuri
authors.forename: Daniel D
authors.initials: DD
authors.lastname: MacDougall
authors.forename: Ruben L
authors.initials: RL
authors.lastname: Gonzalez
mesh_terms: D002232:Carbocyanines / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000378:metabolism; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010441:Peptide Chain Elongation, Translational; D011487:Protein Conformation; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D046911:Macromolecular Substances; D012269:Ribosomal Proteins; C085321:cyanine dye 5; C028546:ribosomal protein L1; D012343:RNA, Transfer