1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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The architecture of EMC reveals a path for membrane protein insertion

  1. John P O'Donnell
  2. Ben Photon Phillips
  3. Yuichi Yagita
  4. Szymon Juszkiewicz
  5. Armin Wagner
  6. Duccio Malinverni
  7. Robert J Keenan
  8. Elizabeth A Miller
  9. Ramanujan S Hegde  Is a corresponding author
  1. MRC Laboratory of Molecular Biology, United Kingdom
  2. Diamond Light Source, United Kingdom
  3. University of Chicago, United States
Research Article
  • Cited 27
  • Views 3,725
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Cite this article as: eLife 2020;9:e57887 doi: 10.7554/eLife.57887

Abstract

Approximately 25% of eukaryotic genes code for integral membrane proteins that are assembled at the endoplasmic reticulum. An abundant and widely conserved multi-protein complex termed EMC has been implicated in membrane protein biogenesis, but its mechanism of action is poorly understood. Here, we define the composition and architecture of human EMC using biochemical assays, crystallography of individual subunits, site-specific photocrosslinking, and cryo-EM reconstruction. Our results suggest that EMC's cytosolic domain contains a large, moderately hydrophobic vestibule that can bind a substrate's transmembrane domain (TMD). The cytosolic vestibule leads into a lumenally-sealed, lipid-exposed intramembrane groove large enough to accommodate a single substrate TMD. A gap between the cytosolic vestibule and intramembrane groove provides a potential path for substrate egress from EMC. These findings suggest how EMC facilitates energy-independent membrane insertion of TMDs, explain why only short lumenal domains are translocated by EMC, and constrain models of EMC's proposed chaperone function.

Data availability

Structural coordinates have been deposited in PDB under accession codes 6Y4L and 6Z3W. Cryo-EM data had been deposited to EMDB under accession code EMD-11058. All other data in this study are provided within the manuscript.

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The following previously published data sets were used

Article and author information

Author details

  1. John P O'Donnell

    Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  2. Ben Photon Phillips

    Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  3. Yuichi Yagita

    Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  4. Szymon Juszkiewicz

    Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3361-7264
  5. Armin Wagner

    Harwell Science and Innovation Campus, Diamond Light Source, Didcot, United Kingdom
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8995-7324
  6. Duccio Malinverni

    Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  7. Robert J Keenan

    Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1466-0889
  8. Elizabeth A Miller

    Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    Elizabeth A Miller, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1033-8369
  9. Ramanujan S Hegde

    Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
    For correspondence
    rhegde@mrc-lmb.cam.ac.uk
    Competing interests
    Ramanujan S Hegde, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8338-852X

Funding

Medical Research Council (MC_UP_A022_1007)

  • Ramanujan S Hegde

Medical Research Council (MC_UP_1201/10)

  • Elizabeth A Miller

National Institutes of Health (R01 GM078186)

  • Elizabeth A Miller

National Institutes of Health (R01 GM130051)

  • Robert J Keenan

European Molecular Biology Organization (ALTF 18-2018)

  • John P O'Donnell

Boehringer Ingelheim Fonds

  • Ben Photon Phillips

Naito Foundation

  • Yuichi Yagita

Japanese Biochemical Society

  • Yuichi Yagita

Swiss National Science Foundation (P2ELP3_18910)

  • Duccio Malinverni

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

Reviewing Editor

  1. Volker Dötsch, Goethe University, Germany

Publication history

  1. Received: April 15, 2020
  2. Accepted: May 26, 2020
  3. Accepted Manuscript published: May 27, 2020 (version 1)
  4. Version of Record published: June 12, 2020 (version 2)

Copyright

© 2020, O'Donnell 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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