Photoproduct formation and repair capacity in a mutant of Bacillus cereus 569 producing UV-sensitive spores

Isolation of recombination-defective and UV-sensitive mutants of Bacillus megaterium

“…Very little has been reported on repair or recombination genes in other bacilli, although a mutant of B. cereus that may be similar to uvrD mutants of E. coli has been reported (25). We have begun to isolate mutants of B. megaterium deficient in recombination or repair.…”

Postincision steps of photoproduct removal in a mutant of Bacillus cereus 569 that produces UV-sensitive spores

“…From our previous and present findings, that the UV-sensitive mutant is (i) resistant to alkylating agents (22) and (ii) capable of incision at the damaged site, we exclude the possibility of deficiency in either DNA-glycosylase or APendonuclease. The deficiency seems to be in a step after the incision step.…”

“…Recently, we isolated, by single step mutagenesis, a mutant of Bacillus cereus 569 sensitive to UV in both vegetative and sporal stages (22). The UV-sensitive mutant designated B. cereus 2422 is capable of in situ removal of the sporespecific photoproduct but is deficient in excision of both cyclobutane thymine dimers and sporespecific dimers.…”

“…The purpose of this investigation, therefore, was to examine the incision and postincision steps of pyrimidine dimer removal in this UVsensitive mutant. The bacterial strains and media used throughout this study were described previously (22).…”

“…Cells able to excise UV damage undergo postirradiation degradation of the DNA, manifested as a release of nucleotides into the acid-soluble fraction of the cell and into the surrounding medium (2). A strain that is incision defective (uvrA, B, C) would be expected to show decreased degradation after UV irradiation and incubation (17,22). A mutant that is defective in a step after incision is expected to show variable levels of increased degradation (23).…”