Molecular basis for processing of topoisomerase 1-triggered DNA damage by Apn2/APE2

Autor: Jessica S. Williams, Jessica L. Wojtaszek, Denise C. Appel, Juno Krahn, Bret D. Wallace, Evan Walsh, Thomas A. Kunkel, R. Scott Williams
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Cell Reports, Vol 41, Iss 1, Pp 111448- (2022)
Druh dokumentu: article
ISSN: 2211-1247
DOI: 10.1016/j.celrep.2022.111448
Popis: Summary: Topoisomerase 1 (Top1) incises DNA containing ribonucleotides to generate complex DNA lesions that are resolved by APE2 (Apn2 in yeast). How Apn2 engages and processes this DNA damage is unclear. Here, we report X-ray crystal structures and biochemical analysis of Apn2-DNA complexes to demonstrate how Apn2 frays and cleaves 3′ DNA termini via a wedging mechanism that facilitates 1–6 nucleotide endonucleolytic cleavages. APN2 deletion and DNA-wedge mutant Saccharomyces cerevisiae strains display mutator phenotypes, cell growth defects, and sensitivity to genotoxic stress in a ribonucleotide excision repair (RER)-defective background harboring a high density of Top1-incised ribonucleotides. Our data implicate a wedge-and-cut mechanism underpinning the broad-specificity Apn2 nuclease activity that mitigates mutagenic and genome instability phenotypes caused by Top1 incision at genomic ribonucleotides incorporated by DNA polymerase epsilon.
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