title: The Bacteroides fragilis P20 scavengase homolog is important in the oxidative stress response but is not controlled by OxyR.
abstract: The oxidative stress response of obligate anaerobe, Bacteroides fragilis, is partially controlled by the redox regulator OxyR but an oxyR null mutant maintains a high level of aerotolerance. Studies using two-dimensional polyacrylamide gel electrophoresis showed that a thiol peroxidase-scavengase, Tps, was induced during oxygen exposure of an oxyR mutant. Tps is similar to 'atypical 2-cysteine peroxidases' such as scavengase p20 and it demonstrated catalytic activity against t-butyl hydroperoxide and H(2)O(2). A second gene, oim, encoding a putative membrane protein, was divergently transcribed from tps. Transcriptional analysis indicated that tps and oim were coordinately regulated by oxygen induction via an OxyR-independent mechanism. H(2)O(2) was a less potent inducer than oxygen exposure and in an oxyR mutant the mRNA levels were slightly reduced compared with the wild type. A null mutant of tps had increased sensitivity to killing by t-butyl hydroperoxide and oxygen but an oim mutant was similar to wild type. These data indicate that Tps is important for protection against some forms of oxidative stress.
authors.affiliation: Department of Microbiology & Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Sund
authors.forename: William
authors.initials: W
authors.lastname: Greg Wells
authors.forename: C
authors.initials: C
authors.lastname: Jeffrey Smith
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001441:Bacteroides fragilis / Q000201:enzymology / Q000235:genetics*; D015180:Electrophoresis, Gel, Two-Dimensional; D017353:Gene Deletion; D016296:Mutagenesis; D018384:Oxidative Stress; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D009195:Peroxidase