title: Sensitivity of DNA-repair-deficient strains of Escherichia coli to rifampicin killing.
abstract: We have analyzed the role of RNA polymerase in DNA repair using the antibiotic rifampicin which binds specifically to the beta subunit of the enzyme. Several DNA-repair-deficient strains such as recA, uvr, and polA, and their isogenic parents were used for this study. All repair-deficient strains were found to be hypersensitive to rifampicin killing. Compared to the isogenic parent strains, recA strains are about 50 times more sensitive and the polA strain is about 100 times more sensitive to rifampicin killing. UvrA and uvrB strains are slightly more sensitive to rifampicin than the wild-type strains. The hypersensitivity of repair-deficient strains to rifampicin killing is totally abolished by the introduction of rifampicin-resistant mutations into these strains. We have examined the effect of rifampicin on RNA and protein synthesis in repair-deficient and -proficient strains. RNA and protein synthesis were found to be inhibited by rifampicin to the same extent among all the strains tested. The results also show that the resumption of DNA synthesis was significantly disrupted in DNA-repair-deficient strains following drug removal. Taken together these results suggest that RNA polymerase plays an essential role in DNA metabolism and such function may be replaced by polA and recA gene products and to a lesser extend by uvrA and uvrB gene products.
mesh_terms: D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D014176:Protein Biosynthesis / Q000187:drug effects; D012293:Rifampin / Q000494:pharmacology*; D013045:Species Specificity; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D012293:Rifampin