title: Tyrosyl-DNA phosphodiesterase (Tdp1) participates in the repair of Top2-mediated DNA damage.
abstract: Agents targeting topoisomerases are active against a wide range of human tumors. Stabilization of covalent complexes, converting topoisomerases into DNA-damaging agents, is an essential aspect of cell killing by these drugs. A unique aspect of the repair of topoisomerase-mediated DNA damage is the requirement for pathways that can remove protein covalently bound to DNA. Tyrosyl-DNA phosphodiesterase (Tdp1) is an enzyme that removes phosphotyrosyl moieties bound to the 3' end of DNA. Cells lacking Tdp1 are hypersensitive to camptothecin, consistent with a role for Tdp1 in processing 3' phosphotyrosyl protein-DNA covalent complexes. Because Top2p forms a 5' phosphotyrosyl linkage with DNA, previous work predicted that Tdp1p would not be active against lesions involving Top2p. We found that deletion of the TDP1 gene in yeast confers hypersensitivity to Top2 targeting agents. Combining tdp1 mutations with deletions of genes involved in nonhomologous end joining, excision repair, or postreplication repair enhanced sensitivity to Top2 targeting drugs over the level seen with single mutants, suggesting that Tdp1 may function in collaboration with multiple pathways involved in strand break repair. tdp1 mutations can sensitize yeast cells to drugs targeting Top2 even when TOP1 is deleted. Finally, bacterially expressed yeast Tdp1p is able to remove a peptide derived from yTop2 that is covalently bound to DNA by a 5' phosphotyrosyl linkage. Our results show that Tdp1 plays more general roles in DNA repair than repair of Top1 mediated DNA damage, and may participate in repairing many types of base damage to DNA.
authors.affiliation: Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: Karin C
authors.initials: KC
authors.lastname: Nitiss
authors.forename: Mobeen
authors.initials: M
authors.lastname: Malik
authors.forename: Xiaoping
authors.initials: X
authors.lastname: He
authors.forename: Stephen W
authors.initials: SW
authors.lastname: White
authors.forename: John L
authors.initials: JL
authors.lastname: Nitiss
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D005047:Etoposide / Q000378:metabolism; D006801:Humans; D009154:Mutation; D019384:Nucleic Acid Synthesis Inhibitors / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D000075223:Poly-ADP-Ribose Binding Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000951:Antigens, Neoplasm; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D000075223:Poly-ADP-Ribose Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C073998:RAD2 protein, S cerevisiae; D005047:Etoposide; D004706:Endodeoxyribonucleases; D004720:Endonucleases; C069266:RAD1 protein, S cerevisiae; D010727:Phosphoric Diester Hydrolases; C505435:Tdp1 protein, S cerevisiae; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human; D045643:DNA Repair Enzymes