title: Following movement of domain IV of elongation factor G during ribosomal translocation.
abstract: Translocation of mRNA and tRNAs through the ribosome is catalyzed by a universally conserved elongation factor (EF-G in prokaryotes and EF-2 in eukaryotes). Previous studies have suggested that ribosome-bound EF-G undergoes significant structural rearrangements. Here, we follow the movement of domain IV of EF-G, which is critical for the catalysis of translocation, relative to protein S12 of the small ribosomal subunit using single-molecule FRET. We show that ribosome-bound EF-G adopts distinct conformations corresponding to the pre- and posttranslocation states of the ribosome. Our results suggest that, upon ribosomal translocation, domain IV of EF-G moves toward the A site of the small ribosomal subunit and facilitates the movement of peptidyl-tRNA from the A to the P site. We found no evidence of direct coupling between the observed movement of domain IV of EF-G and GTP hydrolysis. In addition, our results suggest that the pretranslocation conformation of the EF-G-ribosome complex is significantly less stable than the posttranslocation conformation. Hence, the structural rearrangement of EF-G makes a considerable energetic contribution to promoting tRNA translocation.
authors.affiliation: Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642.
authors.forename: Enea
authors.initials: E
authors.lastname: Salsi
authors.affiliation: Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642.
authors.forename: Elie
authors.initials: E
authors.lastname: Farah
authors.affiliation: Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642.
authors.forename: Jillian
authors.initials: J
authors.lastname: Dann
authors.affiliation: Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642 Dmitri_Ermolenko@urmc.rochester.edu.
authors.forename: Dmitri N
authors.initials: DN
authors.lastname: Ermolenko
mesh_terms: D001692:Biological Transport; D002384:Catalysis; D031541:Fluorescence Resonance Energy Transfer; D006160:Guanosine Triphosphate / Q000737:chemistry; D008853:Microscopy; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000737:chemistry; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D014756:Viomycin / Q000737:chemistry
chemical_list: D020653:Peptide Elongation Factor G; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D014756:Viomycin
keywords: ribosome; single-molecule FRET; tRNA translocation; viomycin