1. Biochemistry and Chemical Biology
  2. Chromosomes and Gene Expression
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Fail-safe control of translation initiation by dissociation of eIF2α phosphorylated ternary complexes

  1. Martin D Jennings
  2. Christopher J Kershaw
  3. Tomas Adomavicius
  4. Graham D Pavitt  Is a corresponding author
  1. The University of Manchester, United Kingdom
Research Article
  • Cited 31
  • Views 1,935
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Cite this article as: eLife 2017;6:e24542 doi: 10.7554/eLife.24542

Abstract

Phosphorylation of eIF2α controls translation initiation by restricting the levels of active eIF2-GTP-Met-tRNAi ternary complexes (TC). This modulates the expression of all eukaryotic mRNAs and contributes to the cellular integrated stress response. Key to controlling the activity of eIF2 are translation factors eIF2B and eIF5, thought to primarily function with eIF2-GDP and TC respectively. Using a steady-state kinetics approach with purified proteins we demonstrate that eIF2B binds to eIF2 with equal affinity irrespective of the presence or absence of competing guanine nucleotides. We show that eIF2B can compete with Met-tRNAi for eIF2-GTP and can destabilize TC. When TC is formed with unphosphorylated eIF2, eIF5 can out-compete eIF2B to stabilize TC-eIF5 complexes. However when TC-eIF5 is formed with phosphorylated eIF2, eIF2B outcompetes eIF5 and destabilizes TC. These data uncover competition between eIF2B and eIF5 for TC and identify that phosphorylated eIF2-GTP translation initiation intermediate complexes can be inhibited by eIF2B.

Article and author information

Author details

  1. Martin D Jennings

    Division of Molecular and Cellular Function, The University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  2. Christopher J Kershaw

    Division of Molecular and Cellular Function, The University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Tomas Adomavicius

    Division of Molecular and Cellular Function, The University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Graham D Pavitt

    Division of Molecular and Cellular Function, The University of Manchester, Manchester, United Kingdom
    For correspondence
    graham.pavitt@manchester.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8593-2418

Funding

Biotechnology and Biological Sciences Research Council (BB/L020157/1)

  • Graham D Pavitt

Biotechnology and Biological Sciences Research Council (BB/M006565/1)

  • Graham D Pavitt

Biotechnology and Biological Sciences Research Council (BB/L000652/1)

  • Graham D Pavitt

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

Reviewing Editor

  1. Nahum Sonenberg, McGill University, Canada

Publication history

  1. Received: December 21, 2016
  2. Accepted: March 16, 2017
  3. Accepted Manuscript published: March 18, 2017 (version 1)
  4. Version of Record published: April 25, 2017 (version 2)

Copyright

© 2017, Jennings et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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