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Nat Struct Mol Biol. 2013 Jun;20(6):718-27. doi: 10.1038/nsmb.2567. Epub 2013 Apr 28.

Coordinated conformational and compositional dynamics drive ribosome translocation.

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1
Department of Applied Physics, Stanford University, Stanford, California, USA.

Abstract

During translation elongation, the ribosome compositional factors elongation factor G (EF-G; encoded by fusA) and tRNA alternately bind to the ribosome to direct protein synthesis and regulate the conformation of the ribosome. Here, we use single-molecule fluorescence with zero-mode waveguides to directly correlate ribosome conformation and composition during multiple rounds of elongation at high factor concentrations in Escherichia coli. Our results show that EF-G bound to GTP (EF-G-GTP) continuously samples both rotational states of the ribosome, binding with higher affinity to the rotated state. Upon successful accommodation into the rotated ribosome, the EF-G-ribosome complex evolves through several rate-limiting conformational changes and the hydrolysis of GTP, which results in a transition back to the nonrotated state and in turn drives translocation and facilitates release of both EF-G-GDP and E-site tRNA. These experiments highlight the power of tracking single-molecule conformation and composition simultaneously in real time.

PMID:
23624862
PMCID:
PMC3883222
DOI:
10.1038/nsmb.2567
[Indexed for MEDLINE]
Free PMC Article
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