Role of Trypanosoma cruzi nucleoside diphosphate kinase 1 in DNA-damage responses

NME23/NDPK proteins are well conserved proteins found in all living organism. Besides their catalytic activity of nucleoside diphosphate kinase (NDPK) they are considered multifunctional, which were first characterized as non-metastatic proteins in mammalian cells. Later, increasing evidences placed NME/NDPK as proteins involved in DNA stability such as gene regulation and DNA-repair. TcNDPK1 is the canonical NDPK isoform present in the parasite Trypanosoma cruzi, orthologous to NME23-H1/H2 which has been shown to have in vitro nuclease activity and DNA-binding properties. In the present study we investigate the role of TcNDPK1 in DNA-damage responses using heterologous gene expression systems and over-expression in epimastigote cells. We found that different strains of bacteria, WT and ndk-mutants, expressing the enzyme decreased about 5 fold and 18 fold the spontaneous mutation rate, respectively. In addition, yeasts lacking the endogenous gene YNK1 (YNK1-) and expressing TcNDPK1, were significantly more resistant to different concentrations of hydrogen peroxide and were less sensible to UV radiation than controls. Parasites over-expressing TcNDPK1 were able to withstand different genotoxic stresses caused by hydrogen peroxide, phleomycin and hidroxyurea. In addition, under oxidative damage, TcNDPK1 over-expressing parasites presented lesser genomic damage and augmented levels of poly(ADP)ribose and poly(ADP)ribose polymerase, an enzyme involved in DNA repair. These results strongly suggest that TcNDPK1 is involved in the maintenance of parasite genomic-DNA integrity, thus, giving rise to a novel function.