Polymerase κ Recruits DDX23 To Promote R-Loop Resolution

Genome stability is constantly threatened by DNA damage and noncanonical nucleic acid structures, e.g., R-loops. Translesion synthesis (TLS) constitutes a major pathway for cells to cope with unrepaired DNA lesions. In this vein, polymerase κ (Pol κ) was shown to maintain genome stability by promoting error-free bypass of minor-groove N²-modified 2'-deoxyguanosine adducts and by participating in DNA repair. To explore functions of Pol κ, we employed two independent approaches, proximity labeling and affinity pull-down, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, to profile the Pol κ-interaction proteome. We found that Pol κ interacts with DDX23 and the polymerase is enriched at R-loop loci in chromatin. In addition, Pol κ recruits DDX23 to R-loop sites to promote DDX23-mediated R-loop resolution, where individual ablation of Pol κ and DDX23 led to augmented accumulation of R-loops in cells. Together, we discovered an interaction between Pol κ and DDX23 and revealed the functions of this interaction in R-loop resolution.