Catalytic and noncatalytic functions of DNA polymerase K in translesion DNA synthesis
Abstract
Translesion DNA synthesis (TLS) is a cellular process that enables the bypass of DNA lesions encountered during DNA replication and is emerging as a primary target of chemotherapy. Among vertebrate DNA polymerases, polymerase kappa (Pol kappa) has the distinctive ability to bypass minor groove DNA adducts in vitro. However, Pol kappa is also required for cells to overcome major groove DNA adducts but the basis of this requirement is unclear. Here, we combine CRISPR base-editor screening technology in human cells with TLS analysis of defined DNA lesions in Xenopus egg extracts to unravel the functions and regulations of Pol kappa during lesion bypass. Strikingly, we show that Pol kappa has two main functions during TLS, which are differentially regulated by Rev1 binding. On the one hand, Pol kappa is essential to replicate across a minor groove DNA lesion in a process that depends on PCNA ubiquitylation but is independent of Rev1. On the other hand, through its cooperative interaction with Rev1 and ubiquitylated PCNA, Pol kappa appears to stabilize the Rev1-Pol zeta extension complex on DNA to allow extension past major groove DNA lesions and abasic sites, in a process that is independent of Pol kappa's catalytic activity. Together, our work identifies catalytic and noncatalytic functions of Pol kappa in TLS and reveals important regulatory mechanisms underlying the unique domain architecture present at the C-terminal end of Y-family TLS polymerases. Show more
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https://doi.org/10.3929/ethz-b-000696753Publication status
publishedExternal links
Journal / series
Nature Structural & Molecular BiologyPublisher
NatureSubject
DNA adducts; Stalled forks; Translesion synthesisMore
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