Catalytic-Dependent Role of DNA Polymerase κ in Nucleotide Excision Repair

DNA polymerase kappa (pol κ) is an error-prone Y-family polymerase primarily associated with translesion DNA synthesis (TLS), a DNA damage tolerance mechanism that prevents replication fork stalling. Pol κ has been implicated in other DNA repair and tolerance pathways such as nucleotide excision repair (NER). However, the role of error-prone pol κ in the NER pathway remains unclear. We sought to investigate if pol κ had a catalytic role in NER by using the pol κ selective nucleoside analogue, N²-(4-ethynylbenzyl)-2'-deoxyguanosine (EBndG). Here, we identified robust, cell cycle-independent catalytic activity of pol κ in cells not treated with DNA-damaging agents. We identified approximately 40% of pol κ catalytic activity was reduced with loss of either XPC or XPA, but not CSB, indicating pol κ has a role in global genome-NER. We monitored pol κ catalytic activity after treatment with benzo(a)pyrene diol epoxide and UVB radiation, and we observed that pol κ catalytic activity increased in an NER-dependent manner. Our study highlights that pol κ is consistently active in cells and possesses a key catalytic role in NER.