Open AccessOxidized nucleotide insertion by pol β confounds ligation during base excision repair
Author(s) -
Melike Çağlayan,
Julie K. Horton,
DaPeng Dai,
Donna F. Stefanick,
Samuel H. Wilson
Publication year - 2017
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/ncomms14045
Subject(s) - base excision repair , nucleotide excision repair , nucleotide , dna , dna polymerase , purine , dna damage , dna repair , microbiology and biotechnology , dna oxidation , ligation , chemistry , dna replication , oxidative stress , polymerase , base pair , biochemistry , biology , gene , enzyme
Oxidative stress in cells can lead to accumulation of reactive oxygen species and oxidation of DNA precursors. Oxidized purine nucleotides can be inserted into DNA during replication and repair. The main pathway for correcting oxidized bases in DNA is base excision repair (BER), and in vertebrates DNA polymerase β (pol β) provides gap filling and tailoring functions. Here we report that the DNA ligation step of BER is compromised after pol β insertion of oxidized purine nucleotides into the BER intermediate in vitro . These results suggest the possibility that BER mediated toxic strand breaks are produced in cells under oxidative stress conditions. We observe enhanced cytotoxicity in oxidizing-agent treated pol β expressing mouse fibroblasts, suggesting formation of DNA strand breaks under these treatment conditions. Increased cytotoxicity following MTH1 knockout or treatment with MTH1 inhibitor suggests the oxidation of precursor nucleotides.