title: Characterization of the organic hydroperoxide resistance system of Brucella abortus 2308.
abstract: The organic hydroperoxide resistance protein Ohr has been identified in numerous bacteria where it functions in the detoxification of organic hydroperoxides, and expression of ohr is often regulated by a MarR-type regulator called OhrR. The genes annotated as BAB2_0350 and BAB2_0351 in the Brucella abortus 2308 genome sequence are predicted to encode OhrR and Ohr orthologs, respectively. Using isogenic ohr and ohrR mutants and lacZ promoter fusions, it was determined that Ohr contributes to resistance to organic hydroperoxide, but not hydrogen peroxide, in B. abortus 2308 and that OhrR represses the transcription of both ohr and ohrR in this strain. Moreover, electrophoretic mobility shift assays and DNase I footprinting revealed that OhrR binds directly to a specific region in the intergenic region between ohr and ohrR that shares extensive nucleotide sequence similarity with so-called "OhrR boxes" described in other bacteria. While Ohr plays a prominent role in protecting B. abortus 2308 from organic hydroperoxide stress in in vitro assays, this protein is not required for the wild-type virulence of this strain in cultured murine macrophages or experimentally infected mice.
authors: Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina, USA.
authors: Clayton C
authors: CC
authors: Caswell
authors: John E
authors: JE
authors: Baumgartner
authors: Daniel W
authors: DW
authors: Martin
authors: R Martin
authors: RM
authors: Roop
mesh_terms: D000818:Animals; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002003:Brucella abortus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D002006:Brucellosis / Q000382:microbiology; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000378:metabolism; D004195:Disease Models, Animal; D024881:Drug Resistance, Bacterial; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity*; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D009930:Organic Chemicals / Q000378:metabolism / Q000633:toxicity*; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009930:Organic Chemicals; D012097:Repressor Proteins; D006861:Hydrogen Peroxide; D001616:beta-Galactosidase