Interface between 40S exit channel protein uS7/Rps5 and eIF2α modulates start codon recognition in vivo

  1. Jyothsna Visweswaraiah
  2. Alan G Hinnebusch  Is a corresponding author
  1. National Institutes of Health, United States

Abstract

The eukaryotic pre-initiation complex (PIC) bearing the eIF2•GTP•Met-tRNAiMet ternary complex (TC) scans the mRNA for an AUG codon in favorable context. AUG recognition evokes rearrangement of the PIC from an open, scanning to a closed, arrested conformation. Cryo-EM reconstructions of yeast PICs suggest remodeling of the interface between 40S protein Rps5/uS7 and eIF2α between open and closed states; however, its importance was unknown. uS7 substitutions disrupting eIF2α contacts favored in the open complex increase initiation at suboptimal sites, and uS7-S223D stabilizes TC binding to PICs reconstituted with a UUG start codon, indicating inappropriate rearrangement to the closed state. Conversely, uS7-D215 substitutions, perturbing uS7-eIF2α interaction in the closed state, confer the opposite phenotypes of hyperaccuracy and (for D215L) accelerated TC dissociation from reconstituted PICs. Thus, remodeling of the uS7/eIF2α interface appears to stabilize first the open, and then the closed state of the PIC to promote accurate AUG selection in vivo.

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Author details

  1. Jyothsna Visweswaraiah

    Laboratory of Gene Regulation and Development, NIH National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
    Competing interests
    No competing interests declared.
  2. Alan G Hinnebusch

    Laboratory of Gene Regulation and Development, NIH National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
    For correspondence
    ahinnebusch@nih.gov
    Competing interests
    Alan G Hinnebusch, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1627-8395

Funding

Intramural Program of the National Institutes of Health (HD001004)

  • Jyothsna Visweswaraiah

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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  1. Jyothsna Visweswaraiah
  2. Alan G Hinnebusch
(2017)
Interface between 40S exit channel protein uS7/Rps5 and eIF2α modulates start codon recognition in vivo
eLife 6:e22572.
https://doi.org/10.7554/eLife.22572

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https://doi.org/10.7554/eLife.22572