N- and C-terminal residues of eIF1A have opposing effects on the fidelity of start codon selection

Christie A. Fekete, Sarah F. Mitchell, Vera A. Cherkasova, Drew Applefield, Mikkel A. Algire, David Maag, Adesh K. Saini, Jon R. Lorsch, Alan G. Hinnebusch

Research output: Contribution to journalArticlepeer-review

Abstract

Translation initiation factor eIF1A stimulates preinitiation complex (PIC) assembly and scanning, but the molecular mechanisms of its functions are not understood. We show that the F131A,F133A mutation in the C-terminal tail (CTT) of eIF1A impairs recruitment of the eIF2-GTP-Met-tRNAiMet ternary complex to 40S subunits, eliminating functional coupling with eIF1. Mutating residues 17-21 in the N-terminal tail (NTT) of eIF1A also reduces PIC assembly, but in a manner rescued by eIF1. Interestingly, the 131,133 CTT mutation enhances initiation at UUG codons (Sui- phenotype) and decreases leaky scanning at AUG, while the NTT mutation 17-21 suppresses the Sui- phenotypes of eIF5 and eIF2β mutations and increases leaky scanning. These findings and the opposite effects of the mutations on eIF1A binding to reconstituted PICs suggest that the NTT mutations promote an open, scanning-conducive conformation of the PIC, whereas the CTT mutations 131,133 have the reverse effect. We conclude that tight binding of eIF1A to the PIC is an important determinant of AUG selection and is modulated in opposite directions by residues in the NTT and CTT of eIF1A.

Original languageEnglish (US)
Pages (from-to)1602-1614
Number of pages13
JournalEMBO Journal
Volume26
Issue number6
DOIs
StatePublished - Mar 21 2007

Keywords

  • GCN4
  • Initiation
  • Saccharomyces
  • Translation
  • eIF1A

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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