title: Enzymatic recognition and biological effects of DNA damage induced by 3-carbethoxypsoralen plus UVA.
abstract: The specific recognition of DNA modifications by repair endonucleases was used to characterize damage induced by 3-carbethoxypsoralen (3-CPs) plus UvA in M13mp8 replicative form I (RF-I) DNA. Under the conditions used, 3-CPs plus UVA generates DNA base modifications which are recognized by the UvrABC complex and the Fpg protein of E. coli. The rate of formation of UvrABC sensitive sites is 3-4-fold higher than that of Fpg sensitive sites. In addition a small number of sites of base loss (sensitive to Nfo protein) were observed. M13mp8 RF-I DNA treated with 3-CPs plus UVA was tested for transfection efficiency in E. coli mutants defective in either Fpg protein and/or UvrABC complex. The survival of 3-CPs plus UVA damaged M13mp8 RF-I DNA was significantly reduced when transfected into uvrA mutants compared to that in the wild-type strain. On the other hand, the survival of 3-CPs plus UVA damaged RF-I DNA was not altered in fpg-1 mutants. These results show that nucleotide excision repair mediated by the UvrABC complex is the major repair pathway involved in the elimination of lethal lesions induced in DNA by 3-CPs plus UVA. Our data suggest that in vitro exposure of M13mp8 RF-I DNA to 3-CPs plus UVA produces predominantly thymine photoaddition and to a lesser extent guanine photooxidation partially due to singlet oxygen generated during photoreaction. The photoaddition products are primarly responsible for the observed lethal effect.
authors.affiliation: LA147 CNRS, U140 INSERM Groupe Réparation des Lésions Radio et Chimioinduites, Institut Gustave Roussy, Villejuif, France.
authors.forename: S
authors.initials: S
authors.lastname: Boiteux
authors.forename: A T
authors.initials: AT
authors.lastname: Yeung
authors.forename: E
authors.initials: E
authors.lastname: Sage
mesh_terms: D001665:Binding Sites / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D004278:DNA, Superhelical / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D004279:DNA, Viral / Q000187:drug effects / Q000528:radiation effects; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043382:DNA-Formamidopyrimidine Glycosylase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D029968:Escherichia coli Proteins; D011564:Furocoumarins / Q000378:metabolism / Q000633:toxicity*; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D010100:Oxygen / Q000633:toxicity; D010777:Photochemistry; D026082:Singlet Oxygen; D014162:Transfection; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D004278:DNA, Superhelical; D004279:DNA, Viral; D029968:Escherichia coli Proteins; D011564:Furocoumarins; D026082:Singlet Oxygen; C017104:3-carbethoxypsoralen; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; C036385:endodeoxyribonuclease uvrABC; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D011088:DNA Ligases; D010100:Oxygen