Cellular determinants of the mutational specificity of 1-nitroso-6-nitropyrene and 1-nitroso-8-nitropyrene in the lacI gene of Escherichia coli
Autor: | N. Laycock, R. Booth, J. Whiteway, J. Koziarz, S. Douville, Iain B. Lambert, I. Lawford, G. Turner, C. Carroll, L. Duval, M.R. Nokhbeh |
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Rok vydání: | 2001 |
Předmět: |
DNA Repair
Guanine Health Toxicology and Mutagenesis Lac repressor Biology medicine.disease_cause Frameshift mutation chemistry.chemical_compound Bacterial Proteins Escherichia coli Lac Repressors Genetics medicine Point Mutation Frameshift Mutation Molecular Biology Gene Pyrenes Base Sequence Escherichia coli Proteins Point mutation Mutagenesis Molecular biology Repressor Proteins carbohydrates (lipids) Amino Acid Substitution chemistry Genes Bacterial Mutation Carcinogens bacteria Mutagens Nitroso Compounds Plasmids Nucleotide excision repair |
Zdroj: | Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis. 484:19-48 |
ISSN: | 0027-5107 |
Popis: | We have characterized 202 lacI − mutations, and 158 dominant lacI − d mutations following treatment of Escherichia coli strain s NR6112 and EE125 with 1-nitroso-6-nitropyrene (1,6-NONP), an activated metabolite of the carcinogen 1,6-dinitropyrene. In all, 91% of the induced point mutations occurred at G:C residues. The −(G:C) frameshifts were the dominant mutational class in the lacI − collections of both NR6112 and EE125, and in the lacI − d collection of NR6112. Frameshift mutations occurred preferentially in runs of guanine residues, and their frequency increased with the length of the reiterated sequence. In strain EE125, which contained the plasmid pKM101, there was a marked stimulation in the frequency of base substitution mutations that was particularly apparent in the lacI − d collection. This study completes a comprehensive analysis of 1194 lacI − and 348 lacI − d mutations induced by either 1,6-NONP or its positional isomer 1-nitroso-8-nitropyrene (1,8-NONP) in strains of E. coli that differ with regard to their ability to carry out nucleotide excision repair and/or their ability to express the translesion synthesis DNA polymerase RI (MucAB) encoded by plasmid pKM101. Among the mutations are 763 frameshift mutations, 367 base substitutions and 47 deletions; these mutations have been characterized at more than 300 distinct sites in the lacI gene. Our studies provide detailed insight into the DNA sequence alterations and mutational mechanisms associated with dinitropyrene mutagenesis. We review the mutational spectra, and discuss cellular lesion repair or tolerance mechanisms that modulate the observed mutational specificity. |
Databáze: | OpenAIRE |
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