Movement of Elongation Factor G between Compact and Extended Conformations. Issue 2 (30th January 2015)

• Record Type: Journal Article
• Authors: Salsi, Enea; Farah, Elie; Netter, Zoe; Dann, Jillian; Ermolenko, Dmitri N.
• Is Part Of: Journal of molecular biology. Volume 427:Issue 2(2015:Jan. 15)
• Page Start: 454
• Page End: 467
• Publication Date: 2015-01-30
• Subjects: EF-G elongation factor G -- smFRET single-molecule molecule Förster resonance energy transfer -- FRET Förster resonance energy transfer -- cryo-EM cryo-electron microscopy -- TIR total internal reflection; ribosome -- tRNA translocation -- smFRET -- conformational dynamics -- viomycin; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2014.11.010
• Languages: English
• ISSNs: 0022-2836

Abstract

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. Graphical abstract: Highlights: Ribosomal translocation is induced by EF-G. Several single-molecule Förster resonance energy transfer assays were developed to follow interdomain rearrangements of EF-G. EF-G samples at least one compact and one extended conformation. Movement between compact and extended conformations of EF-G is not coupled to but likely precedes both GTP hydrolysis and mRNA/tRNA translocation. A flexible connection between domains of EF-G might be required to accommodate rearrangements of EF-G–ribosome complex during translocation.