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 journalArticle

    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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