title: Role of SOS and OxyR systems in the repair of Escherichia coli submitted to hydrogen peroxide under low iron conditions.
abstract: There are at least two mechanisms by which H2O2 induces DNA lesions in Escherichia coli: one in the presence of physiological iron levels and the other in low iron conditions. The survival as well as the induction of SOS response in different DNA repair mutant strains of E coli was evaluated after H2O2 treatment under low iron conditions (pretreatment with an iron chelator). Our results indicate that, in normal iron conditions RecA protein has a relevant role in recombination repair events, while in low iron conditions RecA protein is important as a positive regulator of the SOS response. On the other hand, the oxy delta R mutant is sensitive to the lethal effects of H2O2 only in low iron conditions and this sensitivity cannot be correlated with DNA strand breaks.
authors.affiliation: Laboratório de Radiobiologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: L M
authors.initials: LM
authors.lastname: Asad
authors.forename: N R
authors.initials: NR
authors.lastname: Asad
authors.forename: A B
authors.initials: AB
authors.lastname: Silva
authors.forename: C E
authors.initials: CE
authors.lastname: de Almeida
authors.forename: A C
authors.initials: AC
authors.lastname: Leitão
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D003470:Culture Media; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D000090463:Iron Deficiencies; D012097:Repressor Proteins / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D013014:SOS Response, Genetics / Q000187:drug effects; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C499299:oxyR protein, E coli; D006861:Hydrogen Peroxide