UV-radiation-induced formation of DNA bipyrimidine photoproducts in "Bacillus subtilis" endospores and their repair during germination

• Autores: Ralf Moeller, Thierry Douki, Jean Cadet, Erko Stackebrandt, Wayne L. Nicholson, Petra Rettberg, Günther Reitz, Gerda Horneck
• Localización: International microbiology: official journal of the Spanish Society for Microbiology, ISSN 1139-6709, Vol. 10, Nº. 1, 2007, págs. 39-46
• Idioma: inglés
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• Resumen

  • The spore photoproduct (SP) is the main DNA lesion after UV-C irradiation, and its repair is crucial for the resistance of spores to UV. The aims of the present study were to assess the formation and repair of bipyrimidine photoproducts in spore DNA of various Bacillus subtilis strains using a sensitive HPLC tandem mass spectrometry assay. Strains deficient in nucleotide excision repair, spore photoproduct lyase, homologous recombination (recA), and with wild-type repair capability were investigated. Additionally, one strain deficient in the formation of major small, acid-soluble spore proteins (SASPs) was tested. In all SASP wild-type strains, UV-C irradiation generated almost exclusively SP (>95 %) but also a few by-photoproducts. In the major SASP-deficient strain, SP and by-photoproducts were generated in equal quantities. The status of the UV-induced bipyrimidine photoproducts was determined at different stages of spore germination. After a germination time of 60 min, >75% of the SP was repaired in wild-type strains and in the SASP-deficient strain, while half of the photoinduced SP was removed in the recA-deficient strain. SP-lyase-deficient spores repaired <20% of the SP produced. Thus, SP lyase, with respect to nucleotide excision repair, has a remarkable impact on the removal of SP upon spore germination.