Cloning and Characterization of DNA Polymerase η from Trypanosoma cruzi: Roles for Translesion Bypass of Oxidative Damage

We report the cloning and characterization of the DNA polymerase eta gene from Trypanosoma cruzi (TcPol eta), the causative agent of Chagas disease. This protein, which can bypass cyclobutane pyrimidine dimers, contains motifs that are conserved between Y family polymeroses. In vitro assays showed that the recombinant protein is capable of synthesizing DNA in undamaged primer-templates. Intriguingly, T. cruzi overexpressing TcPol eta does not increase its resistance to UV-light (with or without caffeine) or cisplatin, despite the ability of the protein to enhance UV resistance in a RAD30 mutant of Saccharomyces cerevisiae. Parasites overexpressing TcPol eta are also unable to restore growth after treatment with zeocin or gamma irradiation. T. cruzi overexpressing TcPol eta are more resistant to treatment with hydrogen peroxide (H2O2) compared to nontransfected cells. The observed H2O2 resistance could be associated with its ability to bypass 8-oxoguanine lesions in vitro. The results presented here suggest that TcPol eta is able to bypass UV and oxidative lesions. However the overexpression of the gene only interferes in response to oxidative lesions, possibly due to the presence of these lesions during the S phase. Environ. Mal. Mutagen. 50:375-386, 2009. (C) 2009 Wiley-Liss, Inc,