ИСТИНА

In Eukarya and Archaea, translation initiation factor 2 (e/aIF2α,β,γ) plays a key role in delivering initiator Met¬tRNA to the small ribosomal subunit. Structures of the eukaryotic 43S and 48S complexes bound to the translation initiation factors have been determined (Hashem et al., 2013; Husain et al., 2014). However, there is no interpretable density for eIF2β and γ. Therefore, no model building or refinement was done for eIF2β and γ, and its placement was based on the structure of the archaeal aIF2 (Schmitt et al., 2012; Stolboushkina et al., 2013). aIF2 and eIF2 have a similar structural organization, but the eukaryotic polypeptides have additional terminal extensions, most strongly pronounced in the case of the β subunit. Structure of the eukaryotic eIF2 is a great interesting. Before all attempts to produce and isolate recombinant eukaryotic eIF2γ were unsuccessful. Here, we report about the soluble isolated recombinant human and yeast eIF2γ. In this study, we have used a strong ionic detergent SDS for solubilization of inclusion body proteins and refolded proteins by removing SDS at lower temperature with KCl. At present, we are testing this eIF2γ for binding with other subunits eIF2 and tRNA. After that we plan to use the reconstructed heterotrimeric eIF2 for crystallization. Moreover, we have reconstructed chimeric e/aIF2 as an attractive tool for studying the role of the each subunit of archaeal and eukaryotic e/aIF2 in translation. Using the toeprinting and yeast cell¬free translation system, we have received first results. Chimeric e/aIF2 can support ribosomal scanning during eukaryotic translation initiation but archaeal γ in complex with eukaryotic α and β inhibits translation. This research requires continuation and was supported by the Program for Basic Researches on Molecular and Cellular Biology and Post¬Genomic technologies of the Presidium of RAS to E.A.S.