Nucleic Acids Research Advance Access originally published online on February 1, 2007
Nucleic Acids Research 2007 35(4):1343-1353; doi:10.1093/nar/gkl696
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Nucleic Acids Research, 2007, Vol. 35, No. 4 1343-1353
© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Structural Biology |
Release Factors 2 from Escherichia coli and Thermus thermophilus: structural, spectroscopic and microcalorimetric studies
Department of Biochemistry, P. J. 
afárik University Ko
ice, Slovakia, 1Center of Experimental Medicine, Institute of Biochemistry and Molecular Biology I, University Hospital Hamburg-Eppendorf c/o DESY, Hamburg, Germany, 2European Molecular Biology Laboratory (EMBL), Outstation Hamburg at DESY Hamburg, Germany, 3Institute of Crystallography, Russian Academy of Sciences Moscow, Russia and 4Laboratorium of Biochemistry, University of Bayreuth Universitätsstrasse 30, D-95440 Bayreuth, Germany
*To whom correspondence should be addressed. Tel: +49 921 55 2420; Fax: +49 921 55 2432; Email: mathias.sprinzl{at}uni-bayreuth.de
Received July 4, 2006. Revised September 8, 2006. Accepted September 8, 2006.
Prokaryotic class I release factors (RFs) respond to mRNA stop codons and terminate protein synthesis. They interact with the ribosomal decoding site and the peptidyl-transferase centre bridging these 75 Å distant ribosomal centres. For this an elongated RF conformation, with partially unfolded core domains II·III·IV is required, which contrasts the known compact RF crystal structures. The crystal structure of Thermus thermophilus RF2 was determined and compared with solution structure of T. thermophilus and Escherichia coli RF2 by microcalorimetry, circular dichroism spectroscopy and small angle X-ray scattering. The structure of T. thermophilus RF2 in solution at 20°C is predominantly compact like the crystal structure. Thermodynamic analysis point to an initial melting of domain I, which is independent from the melting of the core. The core domains II·III·IV melt cooperatively at the respective physiological temperatures for T. thermophilus and E. coli. Thermodynamic analyses and the X-ray scattering results for T. thermophilus RF2 in solution suggest that the compact conformation of RF2 resembles a physiological state in absence of the ribosome.
PDB accession no. 2IHR