title: Mutations induced in the supF gene of pSP189 by hydroxyl radical and singlet oxygen: relevance to peroxynitrite mutagenesis.
abstract: We previously showed that the oxidant peroxynitrite (ONOO-) was strongly mutagenic in the supF shuttle vector pSP189 replicated in bacteria or human cells. Qualitative characteristics of the mutational spectra induced by ONOO- differed significantly from those reportedly caused by hydroxyl radical (OH.) in other experimental systems but showed similarities to spectra reportedly produced by singlet oxygen (1O2). The molecular mechanisms of ONOO--mediated DNA damage are unknown. The objective of the present set of experiments was to characterize mutational effects induced in the supF gene of pSP189 by OH* and 1O2 to permit direct comparison with mutational spectra induced by ONOO- in this system. Base substitutions were the major form of mutation induced in plasmids replicated in human (AD293) cells by ONOO- (84%) and 1O2 (71%), whereas OH* induced fewer of them (49%). In plasmids replicated in bacteria (Escherichia coli MBL50), frequencies of base substitutions induced by the three treatments were similar. G:C-to-T:A transversions were the most common form of base substitution induced by ONOO- (75% and 67%, respectively, in AD293- and MBL50-replicated plasmids) and 1O2 (68% and 71%); they were induced at lower frequencies by OH. (51% and 47%). G:C-to-C:G transversions or G:C-to-A:T transitions were induced at almost equal frequencies by both ONOO- and 1O2, whereas OH* induced these mutations at different frequencies in the AD293 system. Collectively, our results confirm that in several important respects mutational spectra induced by ONOO- have greater similarity to spectra induced by 1O2 than to those induced by OH* and suggest that genotoxic derivatives of ONOO- are likely to include species that have DNA-damaging properties resembling those of 1O2 in selectivity for guanine but not identical in sequence specificity.
authors.affiliation: Division of Toxicology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Jeong
authors.forename: M J
authors.initials: MJ
authors.lastname: Juedes
authors.forename: G N
authors.initials: GN
authors.lastname: Wogan
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D009153:Mutagens / Q000737:chemistry / Q000633:toxicity*; D009154:Mutation / Q000187:drug effects*; D009566:Nitrates / Q000737:chemistry / Q000633:toxicity*; D010957:Plasmids; D017382:Reactive Oxygen Species; D014162:Transfection; D014169:Transformation, Bacterial
chemical_list: D009153:Mutagens; D009566:Nitrates; D017382:Reactive Oxygen Species; C039642:peroxynitric acid; D017665:Hydroxyl Radical