title: Repair of DNA strand breaks by the overlapping functions of lesion-specific and non-lesion-specific DNA 3' phosphatases.
abstract: In Saccharomyces cerevisiae, the apurinic/apyrimidinic (AP) endonucleases Apn1 and Apn2 act as alternative pathways for the removal of various 3'-terminal blocking lesions from DNA strand breaks and in the repair of abasic sites, which both result from oxidative DNA damage. Here we demonstrate that Tpp1, a homologue of the 3' phosphatase domain of polynucleotide kinase, is a third member of this group of redundant 3' processing enzymes. Unlike Apn1 and Apn2, Tpp1 is specific for the removal of 3' phosphates at strand breaks and does not possess more general 3' phosphodiesterase, exonuclease, or AP endonuclease activities. Deletion of TPP1 in an apn1 apn2 mutant background dramatically increased the sensitivity of the double mutant to DNA damage caused by H2O2 and bleomycin but not to damage caused by methyl methanesulfonate. The triple mutant was also deficient in the repair of 3' phosphate lesions left by Tdp1-mediated cleavage of camptothecin-stabilized Top1-DNA covalent complexes. Finally, the tpp1 apn1 apn2 triple mutation displayed synthetic lethality in combination with rad52, possibly implicating postreplication repair in the removal of unrepaired 3'-terminal lesions resulting from endogenous damage. Taken together, these results demonstrate a clear role for the lesion-specific enzyme, Tpp1, in the repair of a subset of DNA strand breaks.
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0602, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Vance
authors.forename: T E
authors.initials: TE
authors.lastname: Wilson
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D001483:Base Sequence; D001761:Bleomycin / Q000494:pharmacology; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival; D004249:DNA Damage; D017931:DNA Primers / Q000494:pharmacology; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004271:DNA, Fungal / Q000737:chemistry*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004305:Dose-Response Relationship, Drug; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D009708:Nucleotidases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051721:Rad52 DNA Repair and Recombination Protein; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D000477:Alkylating Agents; D017931:DNA Primers; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D010710:Phosphates; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D001761:Bleomycin; D008741:Methyl Methanesulfonate; D006861:Hydrogen Peroxide; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C083274:Apn1 protein, S cerevisiae; D009708:Nucleotidases; C039170:deoxynucleotide 3'-phosphatase; D019757:Carbon-Oxygen Lyases; C468953:APN2 protein, S cerevisiae; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D045643:DNA Repair Enzymes; D010100:Oxygen