Cycles of autoubiquitination and deubiquitination regulate the ERAD ubiquitin ligase Hrd1
- University of Michigan Medical School, United States
- Harvard Medical School, United States
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.
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Data generated or analysed during this study are included in the manuscript.
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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.
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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Cycles of autoubiquitination and deubiquitination regulate the ERAD ubiquitin ligase Hrd1
eLife 8:e50903.
https://doi.org/10.7554/eLife.50903
