1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics

A point mutation in the nucleotide exchange factor eIF2B constitutively activates the integrated stress response by allosteric modulation

  1. Morgane Boone
  2. Lan Wang
  3. Rosalie Lawrence
  4. Adam Frost
  5. Peter Walter  Is a corresponding author
  6. Michael Schoof  Is a corresponding author
  1. Howard Hughes Medical Institute, University of California, San Francisco, United States
  2. University of California, San Francisco (Adjunct), United States
https://doi.org/10.7554/eLife.76171
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  1. Morgane Boone
  2. Lan Wang
  3. Rosalie Lawrence
  4. Adam Frost
  5. Peter Walter
  6. Michael Schoof
(2022)
A point mutation in the nucleotide exchange factor eIF2B constitutively activates the integrated stress response by allosteric modulation
eLife 11:e76171.
https://doi.org/10.7554/eLife.76171
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Abstract

In eukaryotic cells, stressors reprogram the cellular proteome by activating the integrated stress response (ISR). In its canonical form, stress-sensing kinases phosphorylate the eukaryotic translation initiation factor eIF2 (eIF2-P), which ultimately leads to reduced levels of ternary complex required for initiation of mRNA translation. Previously we showed that translational control is primarily exerted through a conformational switch in eIF2's nucleotide exchange factor, eIF2B, which shifts from its active A-State conformation to its inhibited I-State conformation upon eIF2-P binding, resulting in reduced nucleotide exchange on eIF2 (Schoof et al. 2021). Here, we show functionally and structurally how a single histidine to aspartate point mutation in eIF2B's β subunit (H160D) mimics the effects of eIF2-P binding by promoting an I-State like conformation, resulting in eIF2-P independent activation of the ISR. These findings corroborate our previously proposed A/I-State model of allosteric ISR regulation.

Data availability

All data generated or anaysed during this study are included in the manuscript and source data files. The final structural model has been deposited in PDB under the accession code 7TRJ. Amplicon sequencing data for the CRISPR clones has been deposited in NCBI's Sequence Read Archive (SRA) under accession number PRJNA821864.

The following data sets were generated

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Author details

  1. Morgane Boone

    Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7807-5542

  2. Lan Wang

    Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8931-7201

  3. Rosalie Lawrence

    Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    No competing interests declared.

  4. Adam Frost

    Department of Biochemistry and Biophysics, University of California, San Francisco (Adjunct), San Francisco, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2231-2577

  5. Peter Walter

    Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
    For correspondence
    peter@walterlab.ucsf.edu
    Competing interests
    Peter Walter, is an inventor on U.S. Patent 9708247 held by the Regents of the University of California that describes ISRIB and its analogs. Rights to the invention have been licensed by UCSF to Calico. For the remaining authors, no competing financial interests exist..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6849-708X

  6. Michael Schoof

    Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
    For correspondence
    michael@walterlab.ucsf.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3531-5232

Funding

Calico Life Sciences LLC

  • Peter Walter

The George and Judy Marcus Family Foundation

  • Peter Walter

Belgian-American Educational Foundation

  • Morgane Boone

Damon-Runyon Cancer Research Foundation

  • Lan Wang

Jan Coffin Child Foundation

  • Rosalie Lawrence

Chan Zuckerberg Biohub Investigator Award

  • Adam Frost

HHMI Faculty Scholar grant

  • Adam Frost

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

Copyright

© 2022, Boone 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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  1. Morgane Boone
  2. Lan Wang
  3. Rosalie Lawrence
  4. Adam Frost
  5. Peter Walter
  6. Michael Schoof
(2022)
A point mutation in the nucleotide exchange factor eIF2B constitutively activates the integrated stress response by allosteric modulation
eLife 11:e76171.
https://doi.org/10.7554/eLife.76171

Share this article

https://doi.org/10.7554/eLife.76171

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    1. Biochemistry and Chemical Biology
    2. Cell Biology

    eIF2B conformation and assembly state regulate the integrated stress response

    Michael Schoof, Morgane Boone ... Peter Walter
    Research Article Updated

    The integrated stress response (ISR) is activated by phosphorylation of the translation initiation factor eIF2 in response to various stress conditions. Phosphorylated eIF2 (eIF2-P) inhibits eIF2’s nucleotide exchange factor eIF2B, a twofold symmetric heterodecamer assembled from subcomplexes. Here, we monitor and manipulate eIF2B assembly in vitro and in vivo. In the absence of eIF2B’s α-subunit, the ISR is induced because unassembled eIF2B tetramer subcomplexes accumulate in cells. Upon addition of the small-molecule ISR inhibitor ISRIB, eIF2B tetramers assemble into active octamers. Surprisingly, ISRIB inhibits the ISR even in the context of fully assembled eIF2B decamers, revealing allosteric communication between the physically distant eIF2, eIF2-P, and ISRIB binding sites. Cryo-electron microscopy structures suggest a rocking motion in eIF2B that couples these binding sites. eIF2-P binding converts eIF2B decamers into ‘conjoined tetramers’ with diminished substrate binding and enzymatic activity. Canonical eIF2-P-driven ISR activation thus arises due to this change in eIF2B’s conformational state.