A mutant of Escherichia coli hyper-resistant to a number of DNA damaging agents: location of the mutational site.
A mutant of Escherichia coli, isolated as hyper-resistant to UVC, is found to be hyper-resistant to UVA, H2O2, low concentrations of nalidixic acid, novobiocin, UVA plus H2O2 and UVA plus 8-methoxypsoralen. A mutational site (uvh) conferring the hyper-resistance phenotype to UVC, and presumably to other DNA damaging agents, has been mapped at the 89.9 min region on the chromosome. Complementation analysis with an F-prime uvh+/uvh- diploid strain showed that the uvh+ allele is dominant over uvh- in trans. Studies with a variety of plasmids, carrying various LexA regions, introduced into the UV hyper-resistant strain show that mutation at the uvh locus may be responsible for derepression of the SOS inducible repair system. Based on the results, it is suggested that uvh is a part of the SOS inducible system. A plausible explanation for the hyper-resistance phenotypes for various DNA damaging agents and a model for the genetic control of a second set of putative SOS regulons are presented.
Ahmad
S I
SI
Department of Life Sciences, Nottingham Trent University, UK.
D000483:Alleles; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial / Q000187:drug effects / Q000528:radiation effects*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008730:Methoxsalen / Q000494:pharmacology; D016296:Mutagenesis; D009268:Nalidixic Acid / Q000494:pharmacology; D009675:Novobiocin / Q000494:pharmacology; D010641:Phenotype; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D009675:Novobiocin; D009268:Nalidixic Acid; D006861:Hydrogen Peroxide; D008730:Methoxsalen