Distinct USP25 and USP28 Oligomerization States Regulate Deubiquitinating Activity.

Malte Gersch,Bradford Graves,Angela V Toms,David Komander,Jane L Wagstaff,Stefan M.V Freund

doi:10.1016/j.molcel.2019.02.030

Abstract

SummaryThe evolutionarily related deubiquitinating enzymes (DUBs) USP25 and USP28 comprise an identical overall domain architecture but are functionally non-redundant: USP28 stabilizes c-MYC and other nuclear proteins, and USP25 regulates inflammatory TRAF signaling. We here compare molecular features of USP25 and USP28. Active enzymes form distinctively shaped dimers, with a dimerizing insertion spatially separating independently active catalytic domains. In USP25, but not USP28, two dimers can form an autoinhibited tetramer, where a USP25-specific, conserved insertion sequence blocks ubiquitin binding. In full-length enzymes, a C-terminal domain with a previously unknown fold has no impact on oligomerization, but N-terminal regions affect the dimer-tetramer equilibrium in vitro. We confirm oligomeric states of USP25 and USP28 in cells and show that modulating oligomerization affects substrate stabilization in accordance with in vitro activity data. Our work highlights how regions outside of the catalytic domain enable a conceptually intriguing interplay of DUB oligomerization and activity.

Highlights

The complement of human deubiquitinases (DUBs) comprises 100 enzymes, including more than 50 ubiquitin-specific proteases (USPs) (Clague et al, 2013; Mevissen and Komander, 2017)
What is less clear is the degree of redundancy in the system, for subsets of highly similar USPs that most likely arose from gene duplication events (Figure S1A)
USP28 has been identified as a regulator of the DNA damage response (DDR) (Zhang et al, 2006) and of transcription via stabilization of c-MYC (Popov et al, 2007), which has led to intense study

Summary

Introduction

The complement of human deubiquitinases (DUBs) comprises 100 enzymes, including more than 50 ubiquitin-specific proteases (USPs) (Clague et al, 2013; Mevissen and Komander, 2017). What is less clear is the degree of redundancy in the system, for subsets of highly similar USPs that most likely arose from gene duplication events (Figure S1A). Biological roles of DUBs are currently emerging (Clague et al, 2013), and the available data suggest non-redundant roles even for highly similar enzymes. USP28 has been identified as a regulator of the DNA damage response (DDR) (Zhang et al, 2006) and of transcription via stabilization of c-MYC (Popov et al, 2007), which has led to intense study. USP28 adopts a mostly nuclear localization, and reported substrates include LSD1 involved in chromatin and DNA methylation (Wu et al, 2013) and 53BP1 involved in DDR and cell cycle regulation (Cuella-Martin et al, 2016). USP28 drives colorectal and nonsmall-cell lung cancer (Diefenbacher et al, 2014; Wang et al, 2018), which has made it a sought-after pharmacological target (Harrigan et al, 2018)

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Results

Conclusion