Proteasome assembly influences interaction with ubiquitinated proteins and shuttle factors

Abhishek Chandra, Li Chen, Huiyan Liang, Kiran Madura

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

A major fraction of intracellular protein degradation is mediated by the proteasome. Successful degradation of these substrates requires ubiquitination and delivery to the proteasome followed by protein unfolding and disassembly of the multiubiquitin chain. Enzymes, such as Rpn11, dismantle multiubiquitin chains, and mutations can affect proteasome assembly and activity. We report that different rpn11 mutations can affect proteasome interaction with ubiquitinated proteins. Moreover, proteasomes are unstable in rpn11-1 and do not form productive interactions with multiubiquitinated proteins despite high levels in cell extracts. However, increased levels of ubiquitinated proteins were found associated with shuttle factors. In contrast to rpn11-1, proteasomes expressing a catalytically inactive mutant (rpn11AXA) were more stable and bound very high amounts of ubiquitinated substrates. Expression of the carboxyl-terminal domain of Rpn11 partially suppressed the growth and proteasome stability defects of rpn11-1. These results indicate that ubiquitinated substrates are preferentially delivered to intact proteasome.

Original languageEnglish (US)
Pages (from-to)8330-8339
Number of pages10
JournalJournal of Biological Chemistry
Volume285
Issue number11
DOIs
StatePublished - Mar 12 2010

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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