Discovery and mechanism of K63-linkage-directed deubiquitinase activity in USP53.

ABSTRACT: Ubiquitin-specific proteases (USPs) represent the largest class of human deubiquitinases (DUBs) and comprise its phylogenetically most distant members USP53 and USP54, which are annotated as catalytically inactive pseudoenzymes. Conspicuously, mutations within the USP domain of USP53 cause progressive familial intrahepatic cholestasis. Here, we report the discovery that USP53 and USP54 are active DUBs with high specificity for K63-linked polyubiquitin. We demonstrate how USP53 mutations abrogate catalytic activity, implicating loss of DUB activity in USP53-mediated pathology. Depletion of USP53 increases K63-linked ubiquitination of tricellular junction components. Assays with substrate-bound polyubiquitin reveal that USP54 cleaves within K63-linked chains, whereas USP53 can en bloc deubiq

SUBMITTER: Wendrich K 

PROVIDER: S-EPMC12037411 | biostudies-literature | 2025 May

REPOSITORIES: biostudies-literature