title: An RpoH-like heat shock sigma factor is involved in stress response and virulence in Brucella melitensis 16M.
abstract: B. melitensis 16M genome analysis revealed the presence of six putative sigma factor-encoding genes: rpoD, rpoH1, rpoH2, rpoE1, rpoE2, and rpoN. We mutated all these genes except rpoD. Phenotypic analysis of the mutants reveals that a strain carrying an rpoH2 null mutation (DeltarpoH2) is impaired for growth at 21 and 42 degrees C and shows increased sensitivity to hydrogen peroxide. Compared to the wild-type strain, the DeltarpoH2 mutant is attenuated in all virulence models tested. Three other null mutants (DeltarpoH1, DeltarpoE1, and DeltarpoE2 mutants) are also defective for survival in mice at 4 weeks postinfection. We also demonstrated that rpoH2 deletion strongly reduces the expression of two major virulence factors in B. melitensis, the type IV secretion system and the flagellum.
authors.affiliation: Research Unit in Molecular Biology, URBM, University of Namur, FUNDP, 61 rue de Bruxelles, 5000 Namur, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Delory
authors.forename: Régis
authors.initials: R
authors.lastname: Hallez
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Letesson
authors.forename: Xavier
authors.initials: X
authors.lastname: De Bolle
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015153:Blotting, Western; D017347:Brucella melitensis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D002006:Brucellosis; D002460:Cell Line; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D016254:Mutagenesis, Insertional; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology*; D013696:Temperature; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D006360:Heat-Shock Proteins; D012808:Sigma Factor; D037521:Virulence Factors; C069774:heat-shock sigma factor 32; D006861:Hydrogen Peroxide