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The pretranslocation ribosome is targeted by GTP-bound EF-G in partially activated form

Hauryliuk, Vasili LU orcid ; Mitkevich, Vladimir A. ; Eliseeva, Natalia A. ; Petrushanko, Irina Yu ; Ehrenberg, Måns and Makarov, Alexander A. (2008) In Proceedings of the National Academy of Sciences of the United States of America 105(41). p.15678-15683
Abstract

Translocation of the tRNA·mRNA complex through the bacterial ribosome is driven by the multidomain guanosine triphosphatase elongation factor G (EF-G). We have used isothermal titration calorimetry to characterize the binding of GDP and GTP to free EF-G at 4°C, 20°C, and 37°C. The binding affinity of EF-G is higher to GDP than to GTP at 4°C, but lower at 37°C. The binding enthalpy and entropy change little with temperature in the case of GDP binding but change greatly in the case of GTP binding. These observations are compatible with a large decrease in the solvent-accessible hydrophobic surface area of EF-G on GTP, but not GDP, binding. The explanation we propose is the locking of the switch 1 and switch 2 peptide loops in the G domain... (More)

Translocation of the tRNA·mRNA complex through the bacterial ribosome is driven by the multidomain guanosine triphosphatase elongation factor G (EF-G). We have used isothermal titration calorimetry to characterize the binding of GDP and GTP to free EF-G at 4°C, 20°C, and 37°C. The binding affinity of EF-G is higher to GDP than to GTP at 4°C, but lower at 37°C. The binding enthalpy and entropy change little with temperature in the case of GDP binding but change greatly in the case of GTP binding. These observations are compatible with a large decrease in the solvent-accessible hydrophobic surface area of EF-G on GTP, but not GDP, binding. The explanation we propose is the locking of the switch 1 and switch 2 peptide loops in the G domain of EF-G to the γ-phosphate of GTP. From these data, in conjunction with previously reported structural data on guanine nucleotide-bound EF-G, we suggest that EF-G enters the pretranslocation ribosome as an "activity chimera," with the G domain activated by the presence of GTP but the overall factor conformation in the inactive form typical of a GDP-bound multidomain guanosine triphosphatase. We propose that the active overall conformation of EF-G is attained only in complex with the ribosome in its "ratcheted state," with hybrid tRNA binding sites.

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author
; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
GTPase, Guanine nucleotide binding, Isothermal titration calorimetry, Thermodynamic parameters of interaction
in
Proceedings of the National Academy of Sciences of the United States of America
volume
105
issue
41
pages
6 pages
publisher
National Academy of Sciences
external identifiers
  • pmid:18836081
  • scopus:57349132462
ISSN
0027-8424
DOI
10.1073/pnas.0807912105
language
English
LU publication?
no
additional info
Copyright: Copyright 2019 Elsevier B.V., All rights reserved.
id
e79f33dc-d7ac-457d-bc5f-cbb3664e9ebc
date added to LUP
2021-09-24 20:50:48
date last changed
2024-06-01 17:06:01
@article{e79f33dc-d7ac-457d-bc5f-cbb3664e9ebc,
  abstract     = {{<p>Translocation of the tRNA·mRNA complex through the bacterial ribosome is driven by the multidomain guanosine triphosphatase elongation factor G (EF-G). We have used isothermal titration calorimetry to characterize the binding of GDP and GTP to free EF-G at 4°C, 20°C, and 37°C. The binding affinity of EF-G is higher to GDP than to GTP at 4°C, but lower at 37°C. The binding enthalpy and entropy change little with temperature in the case of GDP binding but change greatly in the case of GTP binding. These observations are compatible with a large decrease in the solvent-accessible hydrophobic surface area of EF-G on GTP, but not GDP, binding. The explanation we propose is the locking of the switch 1 and switch 2 peptide loops in the G domain of EF-G to the γ-phosphate of GTP. From these data, in conjunction with previously reported structural data on guanine nucleotide-bound EF-G, we suggest that EF-G enters the pretranslocation ribosome as an "activity chimera," with the G domain activated by the presence of GTP but the overall factor conformation in the inactive form typical of a GDP-bound multidomain guanosine triphosphatase. We propose that the active overall conformation of EF-G is attained only in complex with the ribosome in its "ratcheted state," with hybrid tRNA binding sites.</p>}},
  author       = {{Hauryliuk, Vasili and Mitkevich, Vladimir A. and Eliseeva, Natalia A. and Petrushanko, Irina Yu and Ehrenberg, Måns and Makarov, Alexander A.}},
  issn         = {{0027-8424}},
  keywords     = {{GTPase; Guanine nucleotide binding; Isothermal titration calorimetry; Thermodynamic parameters of interaction}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{41}},
  pages        = {{15678--15683}},
  publisher    = {{National Academy of Sciences}},
  series       = {{Proceedings of the National Academy of Sciences of the United States of America}},
  title        = {{The pretranslocation ribosome is targeted by GTP-bound EF-G in partially activated form}},
  url          = {{http://dx.doi.org/10.1073/pnas.0807912105}},
  doi          = {{10.1073/pnas.0807912105}},
  volume       = {{105}},
  year         = {{2008}},
}