USP1/UAF1 targets polyubiquitinated PCNA with an exo-cleavage mechanism that can temporarily enrich for monoubiquitinated PCNA.

ABSTRACT: DNA damage tolerance (DDT) is an important pathway that allows cells to bypass DNA lesions during replication. DDT is orchestrated by ubiquitination of PCNA, where monoubiquitinated PCNA (PCNA-Ub) initiates recruitment of TLS polymerases but also serves as a substrate for further ubiquitination, forming K63-polyubiquitinated PCNA that leads to HR-mediated bypass mechanisms. Recent work on USP1/UAF1 inhibition revealed that formation of K48-linked chains also occurs on PCNA, resulting in its proteasomal degradation. USP1/UAF1 is established as deubiquitinating enzyme (DUB) for PCNA-Ub, but little is known about removal of ubiquitin chains on PCNA. Here we show that USP1/UAF1 cleaves both K48 and K63-linked ubiquitin chains on PCNA efficiently, using an exo-cleavage mechanism. Kinetic analys

SUBMITTER: Keijzer N 

PROVIDER: S-EPMC12311017 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature