title: Aerotolerance and peroxide resistance in peroxidase and PerR mutants of Streptococcus pyogenes.
abstract: Survival in aerobic conditions is critical to the pathogenicity of many bacteria. To investigate the means of aerotolerance and resistance to oxidative stress in the catalase-negative organism Streptococcus pyogenes, we used a genomics-based approach to identify and inactivate homologues of two peroxidase genes, encoding alkyl hydroperoxidase (ahpC) and glutathione peroxidase (gpoA). Single and double mutants survived as well as the wild type under aerobic conditions. However, they were more susceptible than the wild type to growth suppression by paraquat and cumene hydroperoxide. In addition, we show that S. pyogenes demonstrates an inducible peroxide resistance response when treated with sublethal doses of peroxide. This resistance response was intact in ahpC and gpoA mutants but not in mutants lacking PerR, a repressor of several genes including ahpC and catalase (katA) in Bacillus subtilis. Because our data indicate that these peroxidase genes are not essential for aerotolerance or induced resistance to peroxide stress in S. pyogenes, genes for a novel mechanism of managing peroxide stress may be regulated by PerR in streptococci.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
authors.forename: K Y
authors.initials: KY
authors.lastname: King
authors.forename: J A
authors.initials: JA
authors.lastname: Horenstein
authors.forename: M G
authors.initials: MG
authors.lastname: Caparon
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D000431:Ethanol / Q000494:pharmacology; D016680:Genome, Bacterial; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010269:Paraquat / Q000494:pharmacology; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D054464:Peroxiredoxins; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C122138:peroxide repressor proteins; D000431:Ethanol; D006861:Hydrogen Peroxide; D010544:Peroxidases; D054464:Peroxiredoxins; D005979:Glutathione Peroxidase; D010269:Paraquat