DNA polymerase kappa from Trypanosoma cruzi localizes to the mitochondria, bypasses 8-oxoguanine lesions and performs DNA synthesis in a recombination intermediate

DNA polymerase kappa (Polκ) is a low-fidelity polymerase that has the ability to bypass several types of lesions. The biological role of this enzyme, a member of the DinB subfamily of Y-family DNA polymerases, has remained elusive. In this report, we studied one of the two copies of Polκ from the protozoan Trypanosoma cruzi (TcPolκ). The role of this TcPolκ copy was investigated by analysing its subcellular localization, its activities in vitro, and performing experiments with parasites that overexpress this polymerase. The TcPOLK sequence has the N-terminal extension which is present only in eukaryotic DinB members, but its C-terminal region is more similar to prokaryotic and archaeal counterparts since it lacks C₂HC motifs and PCNA interaction domain. Our results indicate that in contrast to its previously described orthologues, this polymerase is localized to mitochondria. The overexpression of TcPOLK increases T. cruzi resistance to hydrogen peroxide, and in vitro polymerization assays revealed that TcPolκ efficiently bypasses 8-oxoguanine lesions. Remarkably, our results also demonstrate that the DinB subfamily of polymerases can participate in homologous recombination, based on our findings that TcPolκ increases T. cruzi resistance to high doses of gamma irradiation and zeocin and can catalyse DNA synthesis within recombination intermediates.