The structure of the deubiquitinase USP15 reveals a misaligned catalytic triad and an open ubiquitin-binding channel.
J Biol Chem
; 293(45): 17362-17374, 2018 11 09.
Article
em En
| MEDLINE
| ID: mdl-30228188
ABSTRACT
Ubiquitin-specific protease 15 (USP15) regulates important cellular processes, including transforming growth factor ß (TGF-ß) signaling, mitophagy, mRNA processing, and innate immune responses; however, structural information on USP15's catalytic domain is currently unavailable. Here, we determined crystal structures of the USP15 catalytic core domain, revealing a canonical USP fold, including a finger, palm, and thumb region. Unlike for the structure of paralog USP4, the catalytic triad is in an inactive configuration with the catalytic cysteine â¼10 Å apart from the catalytic histidine. This conformation is atypical, and a similar misaligned catalytic triad has so far been observed only for USP7, although USP15 and USP7 are differently regulated. Moreover, we found that the active-site loops are flexible, resulting in a largely open ubiquitin tail-binding channel. Comparison of the USP15 and USP4 structures points to a possible activation mechanism. Sequence differences between these two USPs mainly map to the S1' region likely to confer specificity, whereas the S1 ubiquitin-binding pocket is highly conserved. Isothermal titration calorimetry monoubiquitin- and linear diubiquitin-binding experiments showed significant differences in their thermodynamic profiles, with USP15 displaying a lower affinity for monoubiquitin than USP4. Moreover, we report that USP15 is weakly inhibited by the antineoplastic agent mitoxantrone in vitro A USP15-mitoxantrone complex structure disclosed that the anthracenedione interacts with the S1' binding site. Our results reveal first insights into USP15's catalytic domain structure, conformational changes, differences between paralogs, and small-molecule interactions and establish a framework for cellular probe and inhibitor development.
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Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Domínio Catalítico
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Simulação de Dinâmica Molecular
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Simulação de Acoplamento Molecular
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Proteases Específicas de Ubiquitina
Limite:
Humans
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article