Specificity of the BRISC deubiquitinating enzyme is not due to selective binding to Lys63-linked polyubiquitin

Eric M. Cooper, Jef D. Boeke, Robert E. Cohen

Research output: Contribution to journalArticlepeer-review

Abstract

BRISC (Brcc36-containing isopeptidase complex) is a four-subunit deubiquitinating (DUB) enzyme that has a catalytic subunit, called Brcc36, that is a member of the JAMM/MPN+ family of zinc metalloproteases. A notable feature of BRISC is its high specificity for cleaving Lys 63-linked polyubiquitin. Here, we show that BRISC selectivity is not due to preferential binding to Lys63-linked polyubiquitin but is instead dictated by how the substrate isopeptide linkage is oriented within the enzyme active site. BRISC possesses a high affinity binding site for the ubiquitin hydrophobic surface patch that accounts for the bulk of the affinity between enzyme and substrate. Although BRISC can interact with either subunit of a diubiquitin conjugate, substrate cleavage occurs only when BRISC is bound to the hydrophobic patch of the distal (i.e. the "S1") ubiquitin at a ubiquitin-ubiquitin cleavage site. The importance of the Lys63-linked proximal (S1′) ubiquitin was underscored by our finding that BRISC could not cleave the isopeptide bond joining a ubiquitin to a non-ubiquitin substrate. Finally, we also show that Abro1, another BRISC subunit, binds directly to Brcc36 and that the Brcc36-Abro1 heterodimer includes a minimal complex with Lys63-specific DUB activity.

Original languageEnglish (US)
Pages (from-to)10344-10352
Number of pages9
JournalJournal of Biological Chemistry
Volume285
Issue number14
DOIs
StatePublished - Apr 2 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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