Repair of platinum-DNA lesions in E. coli by a pathway which does not recognize DNA damage caused by MNNG or UV light.
The adaptive response is an inducible DNA-repair system which diminishes the mutagenic and toxic effects of alkylating agents. A mutant of E. coli constitutive for adaptative repair, BS21, has been isolated. A spontaneous revertant of this strain, BS23, lacks the adaptive response. When compared to its wild-type parent, mutant BS21 showed an increased resistance to the killing and mutagenic effects of a compound which is not a classical alkylating agent, the antitumor drug cis-diamminedichloroplatinum(II) (cis-DDP). However, this resistance to cis-DDP was also found in strain BS23 which lacks the adaptive response. cis-DDP bound to the DNA of all 3 strains with the same efficiency. In addition, we have investigated the effect of UV radiation and we failed to observe a significant difference in the survival and mutagenesis of these strains. This evidence suggests that the resistance of BS21 and BS23 strains to cis-DDP is not a consequence of the adaptive response or increased excision repair.
D002945:Cisplatin / Q000633:toxicity*; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics* / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics*; D008769:Methylnitronitrosoguanidine / Q000633:toxicity; D009154:Mutation / Q000187:drug effects; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D008769:Methylnitronitrosoguanidine; D002945:Cisplatin