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Elife. 2017 Dec 5;6. pii: e31250. doi: 10.7554/eLife.31250.

eIF1A residues implicated in cancer stabilize translation preinitiation complexes and favor suboptimal initiation sites in yeast.

Author information

1
Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, United States.
2
Instituto de Biología Funcional y Genómica, IBFG-CSIC, Universidad de Salamanca, Salamanca, Spain.
3
Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, United States.
4
Institute of Human Genetics, University Duisburg-Essen, Essen, Germany.
5
Eye Cancer Research Group, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.

Abstract

The translation pre-initiation complex (PIC) scans the mRNA for an AUG codon in favorable context, and AUG recognition stabilizes a closed PIC conformation. The unstructured N-terminal tail (NTT) of yeast eIF1A deploys five basic residues to contact tRNAi, mRNA, or 18S rRNA exclusively in the closed state. Interestingly, EIF1AX mutations altering the human eIF1A NTT are associated with uveal melanoma (UM). We found that substituting all five basic residues, and seven UM-associated substitutions, in yeast eIF1A suppresses initiation at near-cognate UUG codons and AUGs in poor context. Ribosome profiling of NTT substitution R13P reveals heightened discrimination against unfavorable AUG context genome-wide. Both R13P and K16D substitutions destabilize the closed complex at UUG codons in reconstituted PICs. Thus, electrostatic interactions involving the eIF1A NTT stabilize the closed conformation and promote utilization of suboptimal start codons. We predict UM-associated mutations alter human gene expression by increasing discrimination against poor initiation sites.

KEYWORDS:

S. cerevisiae; biochemistry; eIF1A; initiation; translation; uveal melanoma; yeast

PMID:
29206102
PMCID:
PMC5756025
DOI:
10.7554/eLife.31250
[Indexed for MEDLINE]
Free PMC Article

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