title: Deoxyribonucleic acid damage by monofunctional mitomycins and its repair in Escherichia coli.
abstract: Exposure of Escherichia coli to the antibiotic mitomycin C (MTC) at a concentration of 0.5 mug/ml caused cross-linkage between complementary strands of deoxyribonucleic acid (DNA). Derivatives of mitomycin, 7-methoxymitosene (7-MMT) and decarbamoyl mitomycin C (DCMTC), at a level as high as 20 mug/ml formed no cross-links between DNA strands. Ultraviolet light-sensitive mutants of E. coli K-12 bearing uvrA, uvrB, uvrC, or recA mutations were more sensitive to the lethal action of 7-MMT and of DCMTC than was the wild-type strain. Treatment of wild-type cells with these antibiotics resulted in the production of single-strand breaks in DNA, which were repaired upon incubation in a growth medium. Such breaks in DNA were not produced in the uvrA and the uvrB mutants. In the uvrC mutant, single-strand breaks were produced by 7-MMT or by DCMTC, but these breaks were not repaired upon incubation. These results are discussed in connection with the mechanism for removal of pyrimidine dimers in ultraviolet-irradiated bacteria.
mesh_terms: D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002621:Chemistry; D004260:DNA Repair; D004269:DNA, Bacterial / Q000032:analysis / Q000096:biosynthesis / Q000302:isolation & purification; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008040:Genetic Linkage / Q000187:drug effects; D005827:Genetics, Microbial; D006358:Hot Temperature; D008826:Microbial Sensitivity Tests; D008937:Mitomycins / Q000494:pharmacology*; D009154:Mutation; D009691:Nucleic Acid Denaturation; D011743:Pyrimidines / Q000378:metabolism; D011830:Radiation Effects; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D002247:Carbon Isotopes; D004269:DNA, Bacterial; D008937:Mitomycins; D011743:Pyrimidines; D014316:Tritium; D013936:Thymidine