PMID: 25404403

Authors:

Clerici M, Luna-Vargas MP, Faesen AC, Sixma TK

Title:

The DUSP-Ubl domain of USP4 enhances its catalytic efficiency by promoting ubiquitin exchange.

Journal:

Nat Commun. 2014 Nov 18;5:5399. doi: 10.1038/ncomms6399.

Abstract:

Ubiquitin-specific protease USP4 is emerging as an important regulator of cellular pathways, including the TGF-beta response, NF-kappaB signalling and splicing, with possible roles in cancer. Here we show that USP4 has its catalytic triad arranged in a productive conformation. Nevertheless, it requires its N-terminal DUSP-Ubl domain to achieve full catalytic turnover. Pre-steady-state kinetics measurements reveal that USP4 catalytic domain activity is strongly inhibited by slow dissociation of ubiquitin after substrate hydrolysis. The DUSP-Ubl domain is able to enhance ubiquitin dissociation, hence promoting efficient turnover. In a mechanism that requires all USP4 domains, binding of the DUSP-Ubl domain promotes a change of a switching loop near the active site. This 'allosteric regulation of product discharge' provides a novel way of regulating deubiquitinating enzymes that may have relevance for other enzyme classes.