title: Movement of elongation factor G between compact and extended conformations.
abstract: Previous structural studies suggested that ribosomal translocation is accompanied by large interdomain rearrangements of elongation factor G (EF-G). Here, we follow the movement of domain IV of EF-G relative to domain II of EF-G using ensemble and single-molecule Förster resonance energy transfer. Our results indicate that ribosome-free EF-G predominantly adopts a compact conformation that can also, albeit infrequently, transition into a more extended conformation in which domain IV moves away from domain II. By contrast, ribosome-bound EF-G predominantly adopts an extended conformation regardless of whether it is interacting with pretranslocation ribosomes or with posttranslocation ribosomes. Our data suggest that ribosome-bound EF-G may also occasionally sample at least one more compact conformation. GTP hydrolysis catalyzed by EF-G does not affect the relative stability of the observed conformations in ribosome-free and ribosome-bound EF-G. Our data support a model suggesting that, upon binding to a pretranslocation ribosome, EF-G moves from a compact to a more extended conformation. This transition is not coupled to but likely precedes both GTP hydrolysis and mRNA/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, USA.
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, USA.
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, USA.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Netter
authors.affiliation: Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA.
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, USA. Electronic address: Dmitri_Ermolenko@urmc.rochester.edu.
authors.forename: Dmitri N
authors.initials: DN
authors.lastname: Ermolenko
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015321:Gene Rearrangement; D020653:Peptide Elongation Factor G / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014178:Translocation, Genetic
chemical_list: D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D012343:RNA, Transfer
keywords: conformational dynamics; ribosome; smFRET; tRNA translocation; viomycin