N-hydroxyarylamine O-acetyltransferase-deficient Escherichia coli strains are resistant to the mutagenicity of nitro compounds.
In Salmonella typhimurium, a single enzyme catalyzes both the acetyl CoA-dependent O-acetylation of hydroxylamines (a key step in the activation of mutagenic nitroaromatic compounds and related aromatic and heterocyclic amines) and the N-acetylation of aromatic amines. S. typhimurium Ames test mutants lacking this activity are highly resistant to the genotoxic effects of nitro compounds. However, such mutants have not yet been obtained in Escherichia coli. We used a PCR-based method to engineer a null mutation (deletion) of the nhoA gene encoding the enzyme in E. coli and we transduced this mutation into a lacZ strain background suitable for use in mutation assays. In E. coli, as in S. typhimurium, nhoA mutants show marked resistance to nitro compound mutagenicity. The new strains provide a clean background for expression of recombinant N-acetyltransferases.
Josephy
P David
PD
Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Guelph, Ontario, Canada.
Summerscales
Joanna
J
DeBruin
Lillian S
LS
Schlaeger
Christof
C
Ho
Jason
J
D000123:Acetyltransferases / Q000172:deficiency*; D000483:Alleles; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D016368:Frameshift Mutation / Q000235:genetics; D007612:Kanamycin / Q000494:pharmacology; D007763:Lac Operon / Q000235:genetics; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D009574:Nitro Compounds / Q000633:toxicity*; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000235:genetics; D014161:Transduction, Genetic; D020742:rhoA GTP-Binding Protein / Q000235:genetics
D000900:Anti-Bacterial Agents; D009153:Mutagens; D009574:Nitro Compounds; D016329:Sp1 Transcription Factor; D007612:Kanamycin; D000123:Acetyltransferases; C019736:N-hydroxyarylamine O-acetyltransferase; D020742:rhoA GTP-Binding Protein