title: A novel 4E-interacting protein in Leishmania is involved in stage-specific translation pathways.
abstract: In eukaryotes, exposure to stress conditions causes a shift from cap-dependent to cap-independent translation. In trypanosomatids, environmental switches are the driving force of a developmental program of gene expression, but it is yet unclear how their translation machinery copes with their constantly changing environment. Trypanosomatids have a unique cap structure (cap-4) and encode four highly diverged paralogs of the cap-binding protein, eIF4E; none were found to genetically complement a yeast mutant failing to express eIF4E. Here we show that in promastigotes, a typical cap-binding complex is anchored through LeishIF4E-4, which associates with components of the cap-binding pre-initiation complex. In axenic amastigotes, expression of LeishIF4E-4 decreases and the protein does not bind the cap, whereas LeishIF4E-1 maintains its expression level and associates with the cap structure and with translation initiation factors. However, LeishIF4E-1 does not interact with eIF4G-like proteins in both life stages, excluding its involvement in cap-dependent translation. Using pull-down assays and mass-spectrometry, we identified a novel, non-conserved 4E-Interacting Protein (Leish4E-IP), which binds to LeishIF4E-1 in promastigotes, but not in amastigotes. Yeast two-hybrid and NMR spectroscopy confirmed the specificity of this interaction. We propose that Leish4E-IP is a translation regulator that is involved in switching between cap-dependent and alternative translation pathways.
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Zinoviev
authors.forename: Mélissa
authors.initials: M
authors.lastname: Léger
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagner
authors.forename: Michal
authors.initials: M
authors.lastname: Shapira
mesh_terms: D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D039562:Eukaryotic Initiation Factor-4F / Q000378:metabolism*; D039642:Eukaryotic Initiation Factors / Q000378:metabolism; D007891:Leishmania / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational; D015800:Protozoan Proteins / Q000378:metabolism*
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D039562:Eukaryotic Initiation Factor-4F; D039642:Eukaryotic Initiation Factors; D015800:Protozoan Proteins