title: Evidence for the mutagenic potential of the vinyl chloride induced adduct, N2, 3-etheno-deoxyguanosine, using a site-directed kinetic assay.
abstract: N2,3-Ethenoguanine (epsilon G) is a product of vinyl chloride reaction with DNA in vivo and of its ultimate metabolite, chloroacetaldehyde, in vitro. The synthesis of the very labile 5'-triphosphate of N2,3-etheno-deoxyguanosine (epsilon dGuo) has made it possible to study the base pairing properties of this derivative placed opposite a defined normal base in a 25-base oligonucleotide template. The kinetic parameters, Km and Vmax were determined from elongation of a [32P]5'-end labeled primer annealed one base prior to the designated template base, epsilon G.T pairs, which would be mutagenic, were formed with a frequency 2- to 4-fold greater than the analogous wobble pair, G.T. The non-mutagenic pairing, epsilon G.C, occurs with a lower frequency than G.C but neither epsilon G.T or epsilon G.C constitute a significant block to replication. The frequency of epsilon G.T formation was similar with all polymerases tested: Escherichia coli DNA polymerase I (Klenow fragment), exonuclease-free Klenow, Drosophila melanogaster polymerase alpha-primase complex and human immunodeficient virus-I reverse transcriptase (HIV-RT). It is concluded that these prokaryotic and eukaryotic replicating enzymes apparently recognize the same structural features, and on replication G----A transitions would occur, which in turn, could initiate malignant transformation. In contrast to the G.T mismatch which is known to have a specific repair system, etheno derivatives are apparently not repaired in vivo.
authors.affiliation: Donner Laboratory, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
authors.forename: B
authors.initials: B
authors.lastname: Singer
authors.forename: J T
authors.initials: JT
authors.lastname: Kuśmierek
authors.forename: W
authors.initials: W
authors.lastname: Folkman
authors.forename: F
authors.initials: F
authors.lastname: Chavez
authors.forename: M K
authors.initials: MK
authors.lastname: Dosanjh
mesh_terms: D001482:Base Composition; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004247:DNA / Q000378:metabolism; D003848:Deoxyguanine Nucleotides / Q000138:chemical synthesis / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000633:toxicity; D007700:Kinetics; D009153:Mutagens / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D011116:Polynucleotide 5'-Hydroxyl-Kinase / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014752:Vinyl Chloride / Q000633:toxicity*
chemical_list: D003848:Deoxyguanine Nucleotides; D009153:Mutagens; C015196:N(2),3-ethenoguanine; C052524:N(2),3-ethenoguanosine; D010761:Phosphorus Radioisotopes; C068266:N(2),3-etheneodeoxyguanosine-5'-triphosphate; D006151:Guanosine; D006147:Guanine; D004247:DNA; D011116:Polynucleotide 5'-Hydroxyl-Kinase; D013936:Thymidine; D014752:Vinyl Chloride