CONICET | Buscador de Institutos y Recursos Humanos

Nucleoside diphosphate kinases are multifunctional enzymes thatparticipate in many cellular processes besides their housekeepingfunction of maintaining intracellular pools of di and tri phosphatenucleotides. TcNDPK1 is an isoform of the enzyme present in Trypanosomacruzi, the parasite that causes Chagas Disease. Amongthe multiple possible functions, several evidences associate TcNDPK1with DNA processing, for example, the in vitro ability of bindingnucleic acids and its nuclease activity. In the present work weevaluate the role of TcNDPK1 in DNA involving processes such asDNA repair using heterologous gene expression systems and overexpression in epimastigote cells. We found that bacterias expressingthe enzyme decreased five times the spontaneous mutationrate respect to controls, measured by counting rifampicin resistantcolonies. In addition, yeasts lacking the endogenous gene YNK1(YNK1-) but expressing TcNDPK1, grew more efficiently, toleratedhigh hydrogen peroxide concentrations (IC50 of 21.2mM and 6.3mMrespectively) and were less sensible to UV irradiation than control.All these results support a possible role of TcNDPK1 in DNA repairmechanisms; however parasites over expressing the enzyme hadan opposite phenotype. We observed a lower growth rate with highermortality, reaching parasite densities two to three folds lower thancontrol in the stationary phase. In addition, these parasites had augmentedexpression levels of activated PARP, an enzyme involved inDNA repair machinery, and twofold increased content of ATP. Suchobservations are in accordance with the generation of DNA damage,what was observed by gel electrophoresis of the genomic DNA. Thenon-protective behavior in parasites could be caused possibly bythe over expression and deregulation of TcNDPK1. Altogether, theseresults exhibit the complexity of TcNDPK1 operation and stronglysuggest its participation in DNA involving processes, giving rise tonovel functions.

enviar mensaje