EIF3 TRANSLATION INITIATION FACTOR STUDIED BY H/D EXCHANGE AND FT-ICR MASS SPECTROMETRY

摘要

The eIF3 complex takes part in the location of the small subunit of the ribosome on the mRNA at the initiation codon AUG. The Saccharomyces cerevisiaea complex is constituted by five subunits and attempts to decipher its tridimensionnal structure are under way. A first path to study the structure of this comples is to complete the identification of binding regions, few of which are currently known. In particular, although it is known that subunits eIF3i and eIF3g interact through the C-terminal domain of eIF3g (eIF3gC1), the eIF3i interaction region is still not known [1]. Hydrogen/deuterium exchanges (HDX) are widely used for structural studies of proteins and multiprotein complexes. The most standard MS approach consists in making a mass measurement of labelled peptides coming from an enzymatic digestion of the protein of interest to determine the rate of deuterium incorporation. The precision on the mass measurement of the FT-ICR allows the unambiguous identification of peptides and its high resolution a simple reading of the isotopics pattern coming from the deuterium labelling [2][3]. In this context, we were have studied by HDX combined with nano-LC MS the structural changes induced by the formation of the eIF3i/eIF3gC1 complex in order to locate the binding region and assess any structural modification induced by binding.