Functional complementation of Leishmania (Leishmania) amazonensis AP endonuclease gene (lamap) in Escherichia coli mutant strains challenged with DNA damage agents

During its life cycle Leishmania spp. face several stress conditions that can cause DNA damages. Base Excision Repair plays an important role in DNA maintenance and it is one of the most conserved mechanisms in all living organisms. DNA repair in trypanosomatids has been reported only for Old World Leishmania species. Here the AP endonuclease from Leishmania (L.) amazonensis was cloned, expressed in Escherichia coli mutants defective on the DNA repair machinery, that were submitted to different stress conditions, showing ability to survive in comparison to the triple null mutant parental strain BW535. Phylogenetic and multiple sequence analyses also confirmed that LAMAP belongs to the AP endonuclease class of proteins.

Polymorphisms in base-excision & nucleotide-excision repair genes & prostate cancer risk in north Indian population.

Background & objectives: Genetic variation in the DNA repair genes might be associated with altered DNA repair capacities (DRC). Reduced DRC due to inherited polymorphisms may increase the susceptibility to cancers. Base excision and nucleotide excision are the two major repair pathways. We investigated the association between two base excision repair (BER) genes (APE1 exon 5, OGG1 exon 7) and two nucleotide excision repair (NER) genes (XPC PAT, XPC exon 15) with risk of prostate cancer (PCa). Methods: The study was designed with 192 histopathologically confirmed PCa patients and 224 age matched healthy controls of similar ethnicity. Genotypes were determined by amplification refractory mutation specific (ARMS) and PCR-restriction fragment length polymorphism (RFLP) methods. Results: Overall, a significant association in NER gene, XPC PAT Ins/Ins (I/I) genotype with PCa risk was observed (Adjusted OR- 2.55, 95%CI-1.22-5.33, P=0.012). XPC exon 15 variant CC genotypes presented statistically significant risk of PCa (Adjusted OR- 2.15, 95% CI-1.09-4.23, P=0.026). However, no association was observed for polymorphism with BER genes. Diplotype analysis of XPC PAT and exon 15 revealed that the frequency of the D-C and I-A diplotype was statistically significant in PCa. The variant genotypes of NER genes were also associated with high Gleason grade. Interpretation & conclusions: The results indicated that there was a significant modifying effect on the association between genotype XPC PAT and exon 15 polymorphism and PCa risk which was further confirmed by diplotype analysis of XPC PAT and exon 15 in north Indian population.