title: A tyrosyl DNA phosphodiesterase 1 from kinetoplastid parasite Leishmania donovani (LdTdp1) capable of removing topo I-DNA covalent complexes.
abstract: Tyrosyl DNA phosphodiesterase 1 (Tdp1) is a member of phospholipase D superfamily, which cleaves a broad range of 3'-DNA adducts, the best characterized of which is the phosphodiester bond formed between DNA and topoisomerase IB. This study describes cloning and functional characterization of the enzyme, termed as LdTdp1 in the kinetoplastid parasite Leishmania donovani. Sequence analysis confirmed conservation of the active site motifs typical for all Tdp1 proteins. LdTdp1 activity was detected in the parasite nucleus as well as in the kinetoplast. The enzyme harbours a nuclear localization signal at its C-terminus. Overexpression of the active enzyme protected the parasites against topoisomerase IB inhibitor camptothecin (CPT) and oxidative agent H(2)O(2)-mediated cytotoxicity and its downregulation rendered the parasites hypersensitive to CPT. Trapping of mutant LdTdp1 on DNA takes place following CPT treatment in L. donovani cells. The expression level and associated activity of LdTdp1 were found to be higher in CPT-resistant L. donovani parasites. Altogether, this is the first report of Tdp1 from the kinetoplastid parasite L. donovani, which actively participates in topoisomerase I-mediated DNA damage repair process and thereby counteracts the cytotoxic effect of topoisomerase I inhibitors.
authors.affiliation: Molecular Parasitology Laboratory, Infectious Disease and Immunology Division, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kokata-700032, India.
authors.forename: Bijoylaxmi
authors.initials: B
authors.lastname: Banerjee
authors.forename: Amit
authors.initials: A
authors.lastname: Roy
authors.forename: Nilkantha
authors.initials: N
authors.lastname: Sen
authors.forename: Hemanta K
authors.initials: HK
authors.lastname: Majumder
mesh_terms: D017209:Apoptosis; D002166:Camptothecin / Q000494:pharmacology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004260:DNA Repair; D016054:DNA, Protozoan / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007893:Leishmania donovani / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D018384:Oxidative Stress; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins; D006861:Hydrogen Peroxide; D010727:Phosphoric Diester Hydrolases; C122147:tyrosyl-DNA phosphodiesterase; D002166:Camptothecin