1. Biochemistry and Chemical Biology
  2. Cell Biology
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Cycles of autoubiquitination and deubiquitination regulate the ERAD ubiquitin ligase Hrd1

  1. Brian G Peterson
  2. Morgan L Glaser
  3. Tom A Rapoport
  4. Ryan D Baldridge  Is a corresponding author
  1. University of Michigan Medical School, United States
  2. Harvard Medical School, United States
Research Article
  • Cited 14
  • Views 2,400
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Cite this article as: eLife 2019;8:e50903 doi: 10.7554/eLife.50903

Abstract

Misfolded proteins in the lumen of the endoplasmic reticulum (ER) are retrotranslocated into the cytosol and polyubiquitinated before being degraded by the proteasome. The multi-spanning ubiquitin ligase Hrd1 forms the retrotranslocation channel and associates with three other membrane proteins (Hrd3, Usa1, Der1) of poorly defined function. The Hrd1 channel is gated by autoubiquitination, but how Hrd1 escapes degradation by the proteasome and returns to its inactive ground state is unknown. Here, we show that autoubiquitination of Hrd1 is counteracted by Ubp1, a deubiquitinating enzyme that requires its N-terminal transmembrane segment for activity towards Hrd1. The Hrd1 partner Hrd3 serves as a brake for autoubiquitination, while Usa1 attenuates Ubp1's deubiquitination activity through an inhibitory effect of its UBL domain. These results lead to a model in which the Hrd1 channel is regulated by cycles of autoubiquitination and deubiquitination, reactions that are modulated by the other components of the Hrd1 complex.

Data availability

Data generated or analysed during this study are included in the manuscript.

Article and author information

Author details

  1. Brian G Peterson

    Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6871-2336
  2. Morgan L Glaser

    Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Tom A Rapoport

    Department of Cell Biology, Harvard Medical School, Boston, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9911-4216
  4. Ryan D Baldridge

    Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, United States
    For correspondence
    ryanbald@med.umich.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7158-7812

Funding

National Institute of General Medical Sciences (R35GM128592)

  • Ryan D Baldridge

National Institute of General Medical Sciences (R01GM052586)

  • Tom A Rapoport

Damon Runyon Cancer Research Foundation (DRG-2184-14)

  • Ryan D Baldridge

Damon Runyon Cancer Research Foundation (DFS-26-18)

  • Ryan D Baldridge

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

Reviewing Editor

  1. Ramanujan S Hegde, MRC Laboratory of Molecular Biology, United Kingdom

Publication history

  1. Received: August 6, 2019
  2. Accepted: November 11, 2019
  3. Accepted Manuscript published: November 12, 2019 (version 1)
  4. Version of Record published: December 16, 2019 (version 2)

Copyright

© 2019, Peterson 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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