title: Role of respiration and glutathione in cadmium-induced oxidative stress in Escherichia coli K-12.
abstract: Cadmium is a widespread pollutant that has been associated with oxidative stress, but the mechanism behind this effect in prokaryotes is still unclear. In this work, we exposed two glutathione deficient mutants (DeltagshA and DeltagshB) and one respiration deficient mutant (DeltaubiE) to a sublethal concentration of cadmium. The glutathione mutants show a similar increase in reactive oxygen species as the wild type. Experiments performed using the DeltaubiE strain showed that this mutant is more resistant to cadmium ions and that Cd-induced reactive oxygen species levels were not altered. In the light of these facts, we conclude that the interference of cadmium with the respiratory chain is the cause of the oxidative stress induced by this metal and that, contrary to previously proposed models, the reactive oxygen species increase is not due to glutathione depletion, although this peptide is crucial for cadmium detoxification.
authors.affiliation: Grupo de Microbiologia Celular e Aplicada (MCA), IBMC, R. Campo Alegre, 823, 4150-180 Porto, Portugal.
authors.forename: Catarina C
authors.initials: CC
authors.lastname: Pacheco
authors.forename: João F
authors.initials: JF
authors.lastname: Passos
authors.forename: A Rita
authors.initials: AR
authors.lastname: Castro
authors.forename: Pedro
authors.initials: P
authors.lastname: Moradas-Ferreira
authors.forename: Paolo
authors.initials: P
authors.lastname: De Marco
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D015169:Colony Count, Microbial; D048168:Escherichia coli K12 / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D005721:Glutamate-Cysteine Ligase / Q000235:genetics; D005978:Glutathione / Q000378:metabolism; D005981:Glutathione Synthase / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics; D050296:Microbial Viability; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000032:analysis
chemical_list: D029968:Escherichia coli Proteins; D017382:Reactive Oxygen Species; D002104:Cadmium; D008780:Methyltransferases; C104639:UbiE protein, E coli; D005721:Glutamate-Cysteine Ligase; D005981:Glutathione Synthase; D005978:Glutathione