title: Oxidatively Generated Guanine(C8)-Thymine(N3) Intrastrand Cross-links in Double-stranded DNA Are Repaired by Base Excision Repair Pathways.
abstract: Oxidatively generated guanine radical cations in DNA can undergo various nucleophilic reactions including the formation of C8-guanine cross-links with adjacent or nearby N3-thymines in DNA in the presence of O2. The G*[C8-N3]T* lesions have been identified in the DNA of human cells exposed to oxidative stress, and are most likely genotoxic if not removed by cellular defense mechanisms. It has been shown that the G*[C8-N3]T* lesions are substrates of nucleotide excision repair in human cell extracts. Cleavage at the sites of the lesions was also observed but not further investigated (Ding et al. (2012) Nucleic Acids Res. 40, 2506-2517). Using a panel of eukaryotic and prokaryotic bifunctional DNA glycosylases/lyases (NEIL1, Nei, Fpg, Nth, and NTH1) and apurinic/apyrimidinic (AP) endonucleases (Apn1, APE1, and Nfo), the analysis of cleavage fragments by PAGE and MALDI-TOF/MS show that the G*[C8-N3]T* lesions in 17-mer duplexes are incised on either side of G*, that none of the recovered cleavage fragments contain G*, and that T* is converted to a normal T in the 3'-fragment cleavage products. The abilities of the DNA glycosylases to incise the DNA strand adjacent to G*, while this base is initially cross-linked with T*, is a surprising observation and an indication of the versatility of these base excision repair proteins.
authors.affiliation: From the Groupe "Réparation de l'ADN," CNRS UMR8200, Université Paris-Sud, Institut de Cancérologie Gustave Roussy, F-94805 Villejuif Cedex, France.
authors.forename: Ibtissam
authors.initials: I
authors.lastname: Talhaoui
authors.affiliation: the Chemistry Department, New York University, New York, New York 10003-5180 vs5@nyu.edu.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shafirovich
authors.affiliation: the Chemistry Department, New York University, New York, New York 10003-5180.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Université Grenoble Alpes, CEA, INAC/SCIB-UMR E3/LAN, F-38000 Grenoble, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Saint-Pierre
authors.affiliation: Department of Molecular Biology and Genetics, Faculty of Biology, al-Farabi Kazakh National University, 530038, Almaty, Kazakhstan.
authors.forename: Zhiger
authors.initials: Z
authors.lastname: Akishev
authors.affiliation: Nazarbayev University Research and Innovation System, Astana 010000, Kazakhstan, and.
authors.forename: Bakhyt T
authors.initials: BT
authors.lastname: Matkarimov
authors.affiliation: Université Grenoble Alpes, CEA, INAC/SCIB-UMR E3/LAN, F-38000 Grenoble, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Gasparutto
authors.affiliation: the Chemistry Department, New York University, New York, New York 10003-5180 ng1@nyu.edu.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Geacintov
authors.affiliation: From the Groupe "Réparation de l'ADN," CNRS UMR8200, Université Paris-Sud, Institut de Cancérologie Gustave Roussy, F-94805 Villejuif Cedex, France, smurat@igr.fr.
authors.forename: Murat
authors.initials: M
authors.lastname: Saparbaev
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D045647:DNA Glycosylases / Q000378:metabolism; D004260:DNA Repair; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D009841:Oligonucleotides; D004247:DNA; D045647:DNA Glycosylases
keywords: DNA damage; DNA endonuclease; DNA repair; base excision repair (BER); nucleotide excision repair