期刊
NUCLEIC ACIDS RESEARCH
卷 39, 期 19, 页码 8404-8415出版社
OXFORD UNIV PRESS
DOI: 10.1093/nar/gkr555
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资金
- US-Israel Binational Foundation (BSF) [2007287]
- Israel Science Foundation (ISF) [395/09]
- National Institutes of Health (NIH) [CA068262]
- Fonds de la Recherche en Sante au Quebec (FRSQ)
- Division of Computing and Communication Foundations
- Direct For Computer & Info Scie & Enginr [2007287] Funding Source: National Science Foundation
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.
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