Thermodynamics of GTP and GDP Binding to Bacterial Initiation Factor 2 Suggests Two Types of Structural Transitions
Hauryliuk, Vasili LU
; Mitkevich, Vladimir A.
; Draycheva, Albena
; Tankov, Stoyan
; Shyp, Viktoriya
; Ermakov, Andrey
; Kulikova, Alexandra A.
; Makarov, Alexander A.
and Ehrenberg, Mans
(2009)
In Journal of Molecular Biology
394(4).
p.621-626
- Abstract
During initiation of messenger RNA translation in bacteria, the GTPase initiation factor (IF) 2 plays major roles in the assembly of the preinitiation 30S complex and its docking to the 50S ribosomal subunit leading to the 70S initiation complex, ready to form the first peptide bond in a nascent protein. Rapid and accurate initiation of bacterial protein synthesis is driven by conformational changes in IF2, induced by GDP-GTP exchange and GTP hydrolysis. We have used isothermal titration calorimetry and linear extrapolation to characterize the thermodynamics of the binding of GDP and GTP to free IF2 in the temperature interval 4-37 °C. IF2 binds with about 20-fold and 2-fold higher affinity for GDP than for GTP at 4 and 37 °C,... (More)
During initiation of messenger RNA translation in bacteria, the GTPase initiation factor (IF) 2 plays major roles in the assembly of the preinitiation 30S complex and its docking to the 50S ribosomal subunit leading to the 70S initiation complex, ready to form the first peptide bond in a nascent protein. Rapid and accurate initiation of bacterial protein synthesis is driven by conformational changes in IF2, induced by GDP-GTP exchange and GTP hydrolysis. We have used isothermal titration calorimetry and linear extrapolation to characterize the thermodynamics of the binding of GDP and GTP to free IF2 in the temperature interval 4-37 °C. IF2 binds with about 20-fold and 2-fold higher affinity for GDP than for GTP at 4 and 37 °C, respectively. The binding of IF2 to both GTP and GDP is characterized by a large heat capacity change (- 868 ± 25 and - 577 ± 23 cal mol- 1 K- 1, respectively), associated with compensatory changes in binding entropy and enthalpy. From our data, we propose that GTP binding to IF2 leads to protection of hydrophobic amino acid residues from solvent by the locking of switch I and switch II loops to the γ-phosphate of GTP, as in the case of elongation factor G. From the large heat capacity change (also upon GDP binding) not seen in the case of elongation factor G, we propose the existence of yet another type of conformational change in IF2, which is induced by GDP and GTP alike. Also, this transition is likely to protect hydrophobic groups from solvent, and its functional relevance is discussed.
(Less)
- author
- Hauryliuk, Vasili
LU
; Mitkevich, Vladimir A.
; Draycheva, Albena
; Tankov, Stoyan
; Shyp, Viktoriya
; Ermakov, Andrey
; Kulikova, Alexandra A.
; Makarov, Alexander A.
and Ehrenberg, Mans
- publishing date
- 2009
- type
- Contribution to journal
- publication status
- published
- keywords
- G nucleotides, GTPases, IF2, isothermal titration calorimetry, translation initiation
- in
- Journal of Molecular Biology
- volume
- 394
- issue
- 4
- pages
- 621 - 626
- publisher
- Elsevier
- external identifiers
-
- scopus:70449524209
- pmid:19837086
- ISSN
- 0022-2836
- DOI
- 10.1016/j.jmb.2009.10.015
- language
- English
- LU publication?
- no
- additional info
- Funding Information: We are grateful to Gemma Atkinson for valuable suggestions on the manuscript. This work was supported by National Institutes of Health grant RO1 GM070768 and the Swedish Research Council (M.E.), the Molecular and Cellular Biology Program of the Russian Academy of Sciences (A.A.M.), the Estonian Scientific Fund grant ETF7616 (V.H.), the European Regional Development Fund through the Center of Excellence in Chemical Biology (V.H.), and the Grant of the President of the Russian Federation for young scientists (МK-162.2009.4) (V.A.M.). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.
- id
- 850423e3-a5a5-461b-b608-943d60c6109f
- date added to LUP
- 2021-09-24 20:50:28
- date last changed
- 2024-01-05 16:33:03
@article{850423e3-a5a5-461b-b608-943d60c6109f,
abstract = {{<p>During initiation of messenger RNA translation in bacteria, the GTPase initiation factor (IF) 2 plays major roles in the assembly of the preinitiation 30S complex and its docking to the 50S ribosomal subunit leading to the 70S initiation complex, ready to form the first peptide bond in a nascent protein. Rapid and accurate initiation of bacterial protein synthesis is driven by conformational changes in IF2, induced by GDP-GTP exchange and GTP hydrolysis. We have used isothermal titration calorimetry and linear extrapolation to characterize the thermodynamics of the binding of GDP and GTP to free IF2 in the temperature interval 4-37 °C. IF2 binds with about 20-fold and 2-fold higher affinity for GDP than for GTP at 4 and 37 °C, respectively. The binding of IF2 to both GTP and GDP is characterized by a large heat capacity change (- 868 ± 25 and - 577 ± 23 cal mol<sup>- 1</sup> K<sup>- 1</sup>, respectively), associated with compensatory changes in binding entropy and enthalpy. From our data, we propose that GTP binding to IF2 leads to protection of hydrophobic amino acid residues from solvent by the locking of switch I and switch II loops to the γ-phosphate of GTP, as in the case of elongation factor G. From the large heat capacity change (also upon GDP binding) not seen in the case of elongation factor G, we propose the existence of yet another type of conformational change in IF2, which is induced by GDP and GTP alike. Also, this transition is likely to protect hydrophobic groups from solvent, and its functional relevance is discussed.</p>}},
author = {{Hauryliuk, Vasili and Mitkevich, Vladimir A. and Draycheva, Albena and Tankov, Stoyan and Shyp, Viktoriya and Ermakov, Andrey and Kulikova, Alexandra A. and Makarov, Alexander A. and Ehrenberg, Mans}},
issn = {{0022-2836}},
keywords = {{G nucleotides; GTPases; IF2; isothermal titration calorimetry; translation initiation}},
language = {{eng}},
number = {{4}},
pages = {{621--626}},
publisher = {{Elsevier}},
series = {{Journal of Molecular Biology}},
title = {{Thermodynamics of GTP and GDP Binding to Bacterial Initiation Factor 2 Suggests Two Types of Structural Transitions}},
url = {{http://dx.doi.org/10.1016/j.jmb.2009.10.015}},
doi = {{10.1016/j.jmb.2009.10.015}},
volume = {{394}},
year = {{2009}},
}