Ectopic Expression of Leishmanial DNA Polymerase β in Escherichia coli Confers Survival Advantage against Ultraviolet Radiation

Abstract

Leishmania donovani encounters oxidative environment in the host macrophage and expected to have robust DNA repair mechanisms. Base Excision Repair (BER), a predominant repair pathway in L. donovani remains unexplored. Presence of mitochondria in eukaryotes has been projected as a symbiotic relationship since long and the role of DNA polymerase β in repair of mitochondrial DNA has gained importance in recent past. We ectopically expressed Leishmania DNA polymerase β (LdPolβ) under inducible promoter in E. coli and found it is biologically active in vitro by using pUC19 as substrate. Further we checked its effect on sensitivity of E. coli to UV rays. We find that heterologous LdPolβ slows down the growth of E. coli and surprisingly, could protect it from lethal effects of UV to a large extent. Co-expression of leishmania DNA Ligase IIIα (LdLigIIIα) has a synergistic effect on survival advantage offered by LdPolβ. Survival advantage given LdPolβ in E. coli is reconfirmed by FACS analysis. Our observations indicate that LdPolβ is crucial for handling ROS induced toxicity inside the mitochondria of the parasite and for its survival inside host macrophage. This studied may lead to explore for finding of the importance of LdPolβ in survival against DNA damaging agents in L. donovani and its role in pathogenesis of leishmaniasis, it would help to discover new target and development of newer drug against Leishmaniasis.