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Mol Cell. 2011 Aug 19;43(4):599-612. doi: 10.1016/j.molcel.2011.05.036.

Ube2w and ataxin-3 coordinately regulate the ubiquitin ligase CHIP.

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  • 1Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA. kscaglio@umich.edu

Abstract

The mechanisms by which ubiquitin ligases are regulated remain poorly understood. Here we describe a series of molecular events that coordinately regulate CHIP, a neuroprotective E3 implicated in protein quality control. Through their opposing activities, the initiator E2, Ube2w, and the specialized deubiquitinating enzyme (DUB), ataxin-3, participate in initiating, regulating, and terminating the CHIP ubiquitination cycle. Monoubiquitination of CHIP by Ube2w stabilizes the interaction between CHIP and ataxin-3, which through its DUB activity limits the length of chains attached to CHIP substrates. Upon completion of substrate ubiquitination, ataxin-3 deubiquitinates CHIP, effectively terminating the reaction. Our results suggest that functional pairing of E3s with ataxin-3 or similar DUBs represents an important point of regulation in ubiquitin-dependent protein quality control. In addition, the results shed light on disease pathogenesis in SCA3, a neurodegenerative disorder caused by polyglutamine expansion in ataxin-3.

Copyright © 2011 Elsevier Inc. All rights reserved.

PMID:
21855799
[PubMed - indexed for MEDLINE]
PMCID:
PMC3166620
Free PMC Article

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