Hydrogen peroxide induces a specific DNA base change profile in the presence of the iron chelator 2,2’ dipyridyl in Escherichia coli
AUTOR(ES)
Felício, D.L., Almeida, C.E.B., Silva, A.B., Leitão, A.C.
FONTE
Brazilian Journal of Medical and Biological Research
DATA DE PUBLICAÇÃO
2009-11
RESUMO
Pretreatment of Escherichia coli cultures with the iron chelator 2,2’-dipyridyl (1 mM) protects against the lethal effects of low concentrations of hydrogen peroxide (<15 mM). However, at H2O2 concentrations equal to or greater than 15 mM, dipyridyl pretreatment increases lethality and mutagenesis, which is attributed to the formation of different types of DNA lesions. We show here that pretreatment with dipyridyl (1 mM) prior to challenge with high H2O2 concentrations (≥15 mM) induced mainly G:C→A:T transitions (more than 100X with 15 mM and more than 250X with 20 mM over the spontaneous mutagenesis rate) in E. coli. In contrast, high H2O2 concentrations in the absence of dipyridyl preferentially induced A:T→T:A transversions (more than 1800X and more than 300X over spontaneous mutagenesis for 15 and 20 mM, respectively). We also show that in the fpg nth double mutant, the rpoB gene mutation (RifS-RifR) induced by 20 mM H2O2 alone (20X higher) was increased in 20 mM H2O2 and dipyridyl-treated cultures (110X higher), suggesting additional and/or different lesions in cells treated with H2O2 under iron deprivation. It is suggested that, upon iron deprivation, cytosine may be the main damaged base and the origin of the pre-mutagenic lesions induced by H2O2.
Documentos Relacionados
- Repair of DNA Lesions Induced by Hydrogen Peroxide in the Presence of Iron Chelators in Escherichia coli: Participation of Endonuclease IV and Fpg
- Repair response of Escherichia coli to hydrogen peroxide DNA damage.
- DNA Microarray-Mediated Transcriptional Profiling of the Escherichia coli Response to Hydrogen Peroxide
- Multiple pathways for repair of hydrogen peroxide-induced DNA damage in Escherichia coli.
- Effects of metal ion chelators on DNA strand breaks and inactivation produced by hydrogen peroxide in Escherichia coli: detection of iron-independent lesions.