title: Evidence for the involvement of nucleotide excision repair in the removal of abasic sites in yeast.
abstract: In eukaryotes, DNA damage induced by ultraviolet light and other agents which distort the helix is removed by nucleotide excision repair (NER) in a fragment approximately 25 to 30 nucleotides long. In humans, a deficiency in NER causes xeroderma pigmentosum (XP), characterized by extreme sensitivity to sunlight and a high incidence of skin cancers. Abasic (AP) sites are formed in DNA as a result of spontaneous base loss and from the action of DNA glycosylases involved in base excision repair. In Saccharomyces cerevisiae, AP sites are removed via the action of two class II AP endonucleases, Apn1 and Apn2. Here, we provide evidence for the involvement of NER in the removal of AP sites and show that NER competes with Apn1 and Apn2 in this repair process. Inactivation of NER in the apn1Delta or apn1Delta apn2Delta strain enhances sensitivity to the monofunctional alkylating agent methyl methanesulfonate and leads to further impairment in the cellular ability to remove AP sites. A deficiency in the repair of AP sites may contribute to the internal cancers and progressive neurodegeneration that occur in XP patients.
authors.affiliation: Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston, Texas 77555-1061, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Torres-Ramos
authors.forename: R E
authors.initials: RE
authors.lastname: Johnson
authors.forename: L
authors.initials: L
authors.lastname: Prakash
authors.forename: S
authors.initials: S
authors.lastname: Prakash
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D045643:DNA Repair Enzymes; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D016296:Mutagenesis; D009153:Mutagens / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D000477:Alkylating Agents; D005656:Fungal Proteins; D009153:Mutagens; C072975:RAD14 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D008741:Methyl Methanesulfonate; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C083274:Apn1 protein, S cerevisiae; D019757:Carbon-Oxygen Lyases; C468953:APN2 protein, S cerevisiae; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D045643:DNA Repair Enzymes