title: Mutagenicity induced by UVC in Escherichia coli cells: reactive oxygen species involvement.
abstract: We previously demonstrated that reactive oxygen species (ROS) could be involved in the DNA damage induced by ultraviolet-C (UVC). In this study, we evaluated singlet oxygen ((1)O(2)) involvement in UVC-induced mutagenesis in Escherichia coli cells. First, we  found that treatment with sodium azide, an (1)O(2) chelator, protected cells against UVC-induced lethality. The survival assay showed that the fpg mutant was more resistant to UVC lethality than the wild-type strain. The rifampicin mutagenesis assay showed that UVC mutagenesis  was inhibited five times more in cells treated with sodium azide, and stimulated 20% more fpg mutant. These results suggest that (1)O(2) plays a predominant role in UVC-induced mutagenesis. (1)O(2) generates a specific mutagenic lesion, 8-oxoG, which is  repaired by Fpg protein. This lesion was measured by GC-TA reversion in the CC104 strain, its fpg mutant (BH540), and both CC104 and BH540 transformed with the plasmid pFPG (overexpression of Fpg protein). This assay showed that mutagenesis was induced 2.5-fold in the GC-TA strain  and 7-fold in the fpg mutant, while the fpg mutant transformed with pFPG was similar to GC-TA strain. This suggests that UVC can also cause ROS-mediated mutagenesis and that the Fpg protein may be involved in this repair.
authors: Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors: A C T
authors: AC
authors: Silva-Júnior
authors: L M B O
authors: LM
authors: Asad
authors: I
authors: I
authors: Felzenszwalb
authors: N R
authors: NR
authors: Asad
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D016296:Mutagenesis / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D017382:Reactive Oxygen Species