title: Alternative excision repair of ultraviolet B- and C-induced DNA damage in dormant and developing spores of Bacillus subtilis.
abstract: The nucleotide excision repair (NER) and spore photoproduct lyase DNA repair pathways are major determinants of Bacillus subtilis spore resistance to UV radiation. We report here that a putative ultraviolet (UV) damage endonuclease encoded by ywjD confers protection to developing and dormant spores of B. subtilis against UV DNA damage. In agreement with its predicted function, a His(6)-YwjD recombinant protein catalyzed the specific incision of UV-irradiated DNA in vitro. The maximum expression of a reporter gene fusion to the ywjD opening reading frame occurred late in sporulation, and this maximal expression was dependent on the forespore-specific RNA polymerase sigma factor, σ(G). Although the absence of YwjD and/or UvrA, an essential protein of the NER pathway, sensitized developing spores to UV-C, this effect was lower when these cells were treated with UV-B. In contrast, UV-B but not UV-C radiation dramatically decreased the survival of dormant spores deficient in both YwjD and UvrA. The distinct range of lesions generated by UV-C and UV-B and the different DNA photochemistry in developing and dormant spores may cause these differences. We postulate that in addition to the UvrABC repair system, developing and dormant spores of B. subtilis also rely on an alternative excision repair pathway involving YwjD to deal with the deleterious effects of various UV photoproducts.
authors.affiliation: Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato, Mexico.
authors.forename: Fernando H
authors.initials: FH
authors.lastname: Ramírez-Guadiana
authors.forename: Marcelo
authors.initials: M
authors.lastname: Barraza-Salas
authors.forename: Norma
authors.initials: N
authors.lastname: Ramírez-Ramírez
authors.forename: Mayte
authors.initials: M
authors.lastname: Ortiz-Cortés
authors.forename: Peter
authors.initials: P
authors.lastname: Setlow
authors.forename: Mario
authors.initials: M
authors.lastname: Pedraza-Reyes
mesh_terms: D000818:Animals; D001412:Bacillus subtilis / Q000502:physiology* / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000528:radiation effects*; D004260:DNA Repair / Q000502:physiology*; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013171:Spores, Bacterial / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial