1. Movement of Elongation Factor G between Compact and Extended Conformations.
- Author
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Salsi, Enea, Farah, Elie, Netter, Zoe, Dann, Jillian, and Ermolenko, Dmitri N.
- Subjects
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ELONGATION factors (Biochemistry) , *CONFORMATIONAL analysis , *PROTEIN structure , *CHROMOSOMAL translocation , *FLUORESCENCE resonance energy transfer , *RIBOSOMES - 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. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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