A Novel 4E-interacting Protein in Leishmania Is Involved in Stage-Specific Translation Pathways

Nucleic Acids Res. 2011 Oct;39(19):8404-15. doi: 10.1093/nar/gkr555. Epub 2011 Jul 14.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Eukaryotic Initiation Factor-4E / metabolism*
  • Eukaryotic Initiation Factor-4F / metabolism*
  • Eukaryotic Initiation Factors / metabolism
  • Leishmania / genetics*
  • Leishmania / growth & development
  • Leishmania / metabolism
  • Peptide Chain Initiation, Translational*
  • Protozoan Proteins / metabolism*

Substances

  • Eukaryotic Initiation Factor-4E
  • Eukaryotic Initiation Factor-4F
  • Eukaryotic Initiation Factors
  • Protozoan Proteins