Specificity of the BRISC deubiquitinating enzyme is not due to selective binding to Lys63-linked polyubiquitin.
J Biol Chem
; 285(14): 10344-52, 2010 Apr 02.
Article
en En
| MEDLINE
| ID: mdl-20032457
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 Lys(63)-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 Lys(63)-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 Lys(63)-specific DUB activity.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Ubiquitinas
/
Poliubiquitina
/
Complejos Multiproteicos
/
Complejo de la Endopetidasa Proteasomal
/
Lisina
/
Proteínas de la Membrana
Límite:
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos