Structural requirement for the induction of the adaptive response in Escherichia coli among N-(substituted alkyl)-N-nitrosoureas

Using E. coli CSH26 transformed with a plasmid carrying an alkA'-lacZ' fused gene, a series of N-(substituted alkyl)-N-nitrosoureas were subjected to a colorimetric assay to evaluate their capacity to induce the adaptive response, an inducible DNA-repair network in E. coli. Some of these derivatives induced the response in greater or lesser degrees, while others did not. Several structural requirements for the induction were disclosed. The capacity of these derivatives to induce the SOS response, which is another inducible DNA-repair network, was also evaluated using E. coli transformed with a plasmid carrying a umuC'-lacZ' fused gene. Since all the derivatives induced the SOS response, the structural requirements for the adaptive response disclosed in this study are substantially related to the molecular mechanism involved in the adaptive response.