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Guanine-nucleotide exchange on ribosome-bound elongation factor G initiates the translocation of tRNAs

Zavialov, Andrey V. ; Hauryliuk, Vasili V. LU orcid and Ehrenberg, M̊ns (2005) In Journal of Biology 4.
Abstract

Background. During the translation of mRNA into polypeptide, elongation factor G (EF-G) catalyzes the translocation of peptidyl-tRNA from the A site to the P site of the ribosome. According to the 'classical' model, EF-G in the GTP-bound form promotes translocation, while hydrolysis of the bound GTP promotes dissociation of the factor from the post-translocation ribosome. According to a more recent model, EF-G operates like a 'motor protein' and drives translocation of the peptidyl-tRNA after GTP hydrolysis. In both the classical and motor protein models, GDP-to-GTP exchange is assumed to occur spontaneously on 'free' EF-G even in the absence of a guanine-nucleotide exchange factor (GEF). Results. We have made a number of findings that... (More)

Background. During the translation of mRNA into polypeptide, elongation factor G (EF-G) catalyzes the translocation of peptidyl-tRNA from the A site to the P site of the ribosome. According to the 'classical' model, EF-G in the GTP-bound form promotes translocation, while hydrolysis of the bound GTP promotes dissociation of the factor from the post-translocation ribosome. According to a more recent model, EF-G operates like a 'motor protein' and drives translocation of the peptidyl-tRNA after GTP hydrolysis. In both the classical and motor protein models, GDP-to-GTP exchange is assumed to occur spontaneously on 'free' EF-G even in the absence of a guanine-nucleotide exchange factor (GEF). Results. We have made a number of findings that challenge both models. First, free EF-G in the cell is likely to be in the GDP-bound form. Second, the ribosome acts as the GEF for EF-G. Third, after guanine-nucleotide exchange, EF-G in the GTP-bound form moves the tRNA2-mRNA complex to an intermediate translocation state in which the mRNA is partially translocated. Fourth, subsequent accommodation of the tRNA2-mRNA complex in the post-translocation state requires GTP hydrolysis. Conclusion. These results, in conjunction with previously published cryo-electron microscopy reconstructions of the ribosome in various functional states, suggest a novel mechanism for translocation of tRNAs on the ribosome by EF-G. Our observations suggest that the ribosome is a universal guanosine-nucleotide exchange factor for EF-G as previously shown for the class-II peptide-release factor 3.

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Contribution to journal
publication status
published
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in
Journal of Biology
volume
4
article number
9
publisher
BioMed Central (BMC)
external identifiers
  • pmid:15985150
  • scopus:20444393817
ISSN
1478-5854
DOI
10.1186/jbiol24
language
English
LU publication?
no
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Copyright: Copyright 2008 Elsevier B.V., All rights reserved.
id
0a5c1a7b-6c01-4f08-b381-3197e1b1e58e
date added to LUP
2021-09-24 20:54:04
date last changed
2024-04-06 10:35:26
@article{0a5c1a7b-6c01-4f08-b381-3197e1b1e58e,
  abstract     = {{<p>Background. During the translation of mRNA into polypeptide, elongation factor G (EF-G) catalyzes the translocation of peptidyl-tRNA from the A site to the P site of the ribosome. According to the 'classical' model, EF-G in the GTP-bound form promotes translocation, while hydrolysis of the bound GTP promotes dissociation of the factor from the post-translocation ribosome. According to a more recent model, EF-G operates like a 'motor protein' and drives translocation of the peptidyl-tRNA after GTP hydrolysis. In both the classical and motor protein models, GDP-to-GTP exchange is assumed to occur spontaneously on 'free' EF-G even in the absence of a guanine-nucleotide exchange factor (GEF). Results. We have made a number of findings that challenge both models. First, free EF-G in the cell is likely to be in the GDP-bound form. Second, the ribosome acts as the GEF for EF-G. Third, after guanine-nucleotide exchange, EF-G in the GTP-bound form moves the tRNA2-mRNA complex to an intermediate translocation state in which the mRNA is partially translocated. Fourth, subsequent accommodation of the tRNA2-mRNA complex in the post-translocation state requires GTP hydrolysis. Conclusion. These results, in conjunction with previously published cryo-electron microscopy reconstructions of the ribosome in various functional states, suggest a novel mechanism for translocation of tRNAs on the ribosome by EF-G. Our observations suggest that the ribosome is a universal guanosine-nucleotide exchange factor for EF-G as previously shown for the class-II peptide-release factor 3.</p>}},
  author       = {{Zavialov, Andrey V. and Hauryliuk, Vasili V. and Ehrenberg, M̊ns}},
  issn         = {{1478-5854}},
  language     = {{eng}},
  publisher    = {{BioMed Central (BMC)}},
  series       = {{Journal of Biology}},
  title        = {{Guanine-nucleotide exchange on ribosome-bound elongation factor G initiates the translocation of tRNAs}},
  url          = {{http://dx.doi.org/10.1186/jbiol24}},
  doi          = {{10.1186/jbiol24}},
  volume       = {{4}},
  year         = {{2005}},
}