Biochemical and kinetic study of eIF5A and ribosome direct interaction, using Saccharomyces cerevisiae and human as models

Abstract

The translation initiation factor 5A (eIF5A) is highly conserved in archaea and eukaryotes and is essential for cell viability. This is the only known protein containing the amino acid hypusine, essential for the function of eIF5A and it is generated in a post-translational modification. After being extensively involved in several cellular processes, only recently it was better determined a role for eIF5A in protein synthesis, specifically during the elongation step. To improve the description and understanding of the mechanism of eIF5A in translation, it is necessary to determine where in the ribosome physical interaction of eIF5A takes place and to which kind of ribosomal complex eIF5A binds to. Recent unpublished results, presented in the PhD thesis of the proponent of this post-doc proposal, showed direct binding of eIF5A only to the large subunit of the ribosome, and the hypusine residue is required for this interaction. Therefore, this project is proposed as a follow-up of the kinetic and biochemical approaches using up-to-date techniques: 1) determination of the types of ribosomal complexes to which eIF5A binds to and searching for competitor or helper components to this binding using fluorescence anisotropy assays; 2) mapping the point sites of direct interaction between eIF5A and the ribosome by rRNA cleavage assays and primer extension analysis; 3) identification of proteins and rRNA that physically interact with eIF5A through induction of crosslinking in vitro. The results of these goals will reveal how and where eIF5A binds the ribosome and will significantly improve the description of the role of this protein in translation.