ESCHERICHIA-COLI LACZ STRAINS ENGINEERED FOR DETECTION OF FRAMESHIFT MUTATIONS INDUCED BY AROMATIC-AMINES AND NITROAROMATIC COMPOUNDS

Escherichia coli lacZ strains CC107-CC111, which detect specific frame shift mutations, were used to study the mutational specificities of 2- nitro-3-methylimidazo[4,5-f]quinoline (NO2-IQ) and rat hepatic S9-acti vated 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). New constructs wer e made in which UvrABC-dependent excision repair was eliminated (strai ns DJ3107-DJ3111), followed by introduction of plasmid pYG219 conferri ng acetyl CoA:arylamine N-acetyltransferase/acetyl CoA:arylhydroxylami ne O-acetyltransferase (NAT/OAT) activity (strains D53207-DJ3211). Sen sitivity to mutagens was greatly enhanced. The mutational specificity of NO2-IQ was identical to that of the corresponding amine, IQ. The mo st prominent mutations caused by the two compounds were -2((CG)(GC)) a nd -1((G)(C)) frameshifts, +1((A)(T)) Frameshifts play a minor role in the pattern of mutational specificity. Induction of all three mutatio ns was similarly influenced by NAT/OAT activation and UvrABC-dependent excision repair. These new tester strains provide an effective tool f or the study of aromatic amine mutational specificity and the influenc es of excision repair and NAT/OAT activation.