title: Class-1 release factor eRF1 promotes GTP binding by class-2 release factor eRF3.
abstract: In eukaryotes, termination of mRNA translation is triggered by the essential polypeptide chain release factors eRF1, recognizing all three stop codons, and eRF3, a member of the GTPase superfamily with a role that has remained opaque. We have studied the kinetic and thermodynamic parameters of the interactions between eRF3 and GTP, GDP and the non-hydrolysable GTP analogue GDPNP in the presence (K(D)(GDP)=1.3+/-0.2 muM, K(D)(GTP) approximately 200 muM and K(D)(GDPNP)>160 muM) as well as absence (K(D)(GDP)=1.9+/-0.3 muM, K(D)(GTP) 0.7+/-0.2 muM and K(D)(GDPNP) approximately 200 muM) of eRF1. From the present data we propose that (i) free eRF3 has a strong preference to bind GDP compared to GTP (ii) eRF3 in complex with eRF1 has much stronger affinity to GTP than free eRF3 (iii) eRF3 in complex with PABP has weak affinity to GTP (iv) eRF3 in complex with eRF1 does not have strong affinity to GDPNP, implying that GDPNP is a poor analogue of GTP for eRF3 binding.
authors.affiliation: Department of Cell and Molecular Biology, Molecular Biology Program, BMC, Box 596, Uppsala University, 75124, Sweden.
authors.forename: Vasili
authors.initials: V
authors.lastname: Hauryliuk
authors.forename: Andrey
authors.initials: A
authors.lastname: Zavialov
authors.forename: Lev
authors.initials: L
authors.lastname: Kisselev
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
mesh_terms: D020558:GTP Phosphohydrolases / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D010443:Peptide Chain Termination, Translational / Q000502:physiology; D010454:Peptide Termination Factors / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry
chemical_list: C489002:ETF1 protein, human; D010454:Peptide Termination Factors; C087971:peptide-chain-release factor 3; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases