%0 Journal Article %T Roles of yeast eIF2α and eIF2β subunits in the binding of the initiator methionyl-tRNA %+ Laboratoire de Biochimie de l'Ecole polytechnique (BIOC) %A Naveau, Marie %A Lazennec-Schurdevin, Christine %A Panvert, Michel %A Dubiez, Etienne %A Mechulam, Yves %A Schmitt, Emmanuelle %< avec comité de lecture %@ 0305-1048 %J Nucleic Acids Research %I Oxford University Press %V 41 %N 1 %P 1047-1057 %8 2013 %D 2013 %R 10.1093/nar/gks1180 %M 23193270 %Z Life Sciences [q-bio]/Biochemistry, Molecular BiologyJournal articles %X Heterotrimeric eukaryotic/archaeal translation initiation factor 2 (e/aIF2) binds initiator methionyl-tRNA and plays a key role in the selection of the start codon on messenger RNA. tRNA binding was extensively studied in the archaeal system. The γ subunit is able to bind tRNA, but the α subunit is required to reach high affinity whereas the β subunit has only a minor role. In Saccharomyces cerevisiae however, the available data suggest an opposite scenario with β having the most important contribution to tRNA-binding affinity. In order to overcome difficulties with purification of the yeast eIF2γ subunit, we designed chimeric eIF2 by assembling yeast α and β subunits to archaeal γ subunit. We show that the β subunit of yeast has indeed an important role, with the eukaryote-specific N- and C-terminal domains being necessary to obtain full tRNA-binding affinity. The α subunit apparently has a modest contribution. However, the positive effect of α on tRNA binding can be progressively increased upon shortening the acidic C-terminal extension. These results, together with small angle X-ray scattering experiments, support the idea that in yeast eIF2, the tRNA molecule is bound by the α subunit in a manner similar to that observed in the archaeal aIF2-GDPNP-tRNA complex. © The Author(s) 2012. Published by Oxford University Press. %G English %2 https://polytechnique.hal.science/hal-00840386/document %2 https://polytechnique.hal.science/hal-00840386/file/1047.full.pdf %L hal-00840386 %U https://polytechnique.hal.science/hal-00840386 %~ X %~ CNRS %~ X-BIOCH %~ X-DEP %~ X-DEP-BIO