Direct, Noncatalytic Mechanism of IKK Inhibition by A20

Brian Skaug, Jueqi Chen, Fenghe Du, Jin He, Averil Ma, Zhijian J. Chen

Research output: Contribution to journalArticle

149 Scopus citations

Abstract

A20 is a potent anti-inflammatory protein that inhibits NF-κB, and A20 dysfunction is associated with autoimmunity and B cell lymphoma. A20 harbors a deubiquitination enzyme domain and can employ multiple mechanisms to antagonize ubiquitination upstream of NEMO, a regulatory subunit of the IκB kinase complex (IKK). However, direct evidence of IKK inhibition by A20 is lacking, and the inhibitory mechanism remains poorly understood. Here we show that A20 can directly impair IKK activation without deubiquitination or impairment of ubiquitination enzymes. We find that polyubiquitin binding by A20, which is largely dependent on A20's seventh zinc-finger motif (ZnF7), induces specific binding to NEMO. Remarkably, this ubiquitin-induced recruitment of A20 to NEMO is sufficient to block IKK phosphorylation by its upstream kinase TAK1. Our results suggest a noncatalytic mechanism of IKK inhibition by A20 and a means by which polyubiquitin chains can specify a signaling outcome.

Original languageEnglish (US)
Pages (from-to)559-571
Number of pages13
JournalMolecular cell
Volume44
Issue number4
DOIs
StatePublished - Nov 18 2011

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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