Branched ubiquitin chain binding and deubiquitination by UCH37 facilitate proteasome clearance of stress-induced inclusions
- Colorado State University, United States
- University of Maryland, United States
- University of Utah School of Medicine, United States
- University of California, Irvine, United States
Abstract
UCH37, also known as UCHL5, is a highly conserved deubiquitinating enzyme (DUB) that associates with the 26S proteasome. Recently it was reported that UCH37 activity is stimulated by branched ubiquitin chain architectures. To understand how UCH37 achieves its unique debranching specificity, we performed biochemical and NMR structural analyses and found that UCH37 is activated by contacts with the hydrophobic patches of both distal ubiquitins that emanate from a branched ubiquitin. In addition, RPN13, which recruits UCH37 to the proteasome, further enhances branched-chain specificity by restricting linear ubiquitin chains from having access to the UCH37 active site. In cultured human cells under conditions of proteolytic stress, we show that substrate clearance by the proteasome is promoted by both binding and deubiquitination of branched polyubiquitin by UCH37. Proteasomes containing UCH37(C88A), which is catalytically inactive, aberrantly retain polyubiquitinated species as well as the RAD23B substrate shuttle factor, suggesting a defect in recycling of the proteasome. These findings provide a foundation to understand how proteasome degradation of substrates modified by a unique ubiquitin chain architecture is aided by a DUB.
Data availability
All data contributed to the results in this manuscript are included in the manuscript and supporting files.
Article and author information
Author details
Christopher P Hill
Funding
National Institute of General Medical Sciences (R01 GM115997)
- Robert E Cohen
National Institute of General Medical Sciences (R21 GM135818)
- Robert E Cohen
National Institute of General Medical Sciences (R01 GM065334)
- David Fushman
National Institute of General Medical Sciences (R01 GM074830)
- Lan Huang
National Institute of General Medical Sciences (R01 GM130144)
- Lan Huang
National Institute of General Medical Sciences (R01 GM098401)
- Tingting Yao
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Song 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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