The enzymatic production of DNA double strand breaks in E. coli K12 after ultraviolet irradiation was observed. Double strand breaks appeared in wild type, polA1, recB21, recA, and exrA strains after incubation in minimal medium. The uvrA6 strain showed no evidence of double strand breakage under the same conditions. The data suggest that uvr+ cells, which are proficient in the incision step of excision repair, accumulate double strand breaks in their DNA as a result of the excision repair process, i.e., arising from closely matched incisions, excision gaps, or incisions and gaps on opposite strands of the DNA twin helix. Furthermore, strains deficient in excision repair subsequent to the incision step (polA, rec, exrA) showed more double strand breaks than the wild type strain. The results raise the possibility that a significant fraction of the lethal events in ultraviolet irradiated, repair proficient (uvr+) cells may be enzymatically induced DNA double strand breaks.
CITATION STYLE
Bonura, T., & Smith, K. C. (1975). Enzymatic production of deoxyribonucleic acid double strand breaks after ultraviolet irradiation of Escherichia coli K 12. Journal of Bacteriology, 121(2), 511–517. https://doi.org/10.1128/jb.121.2.511-517.1975
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