title: Complementation of a DnaK-deficient Escherichia coli strain with the dnaK/dnaJ operon of Brucella ovis reduces the rate of initial intracellular killing within the monocytic cell line U937.
abstract: Facultatively intracellular bacteria express heat shock proteins after phagocytosis by macrophages. Using non-pathogenic Escherichia coli strains and the human monocytic cell line U937, we showed that deletion of the dnaK gene significantly increased the rate of initial intracellular killing of bacteria. Trans-complementation of the deletion mutant with the dnaK/dnaJ operon of Brucella ovis restored the pattern of intracellular elimination of the control strain expressing dnaK. These differences were not observed using antibody-opsonized bacteria and activated cells. In vitro, strains expressing dnaK resisted hydrogen peroxide better than the deletion mutant; in contrast, the mutant complemented by dnaK/dnaJ of B. ovis tolerated low pH and low H2O2 better than the wild-type strain and the deletion mutant. Our results suggested the participation of DnaK in protection of intracellular bacteria against antimicrobial macrophage factors.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U-65, Dept. Biologie-Santé, Université Montpellier II, France.
authors.forename: E
authors.initials: E
authors.lastname: Caron
authors.forename: M
authors.initials: M
authors.lastname: Cellier
authors.forename: J P
authors.initials: JP
authors.lastname: Liautard
authors.forename: S
authors.initials: S
authors.lastname: Köhler
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D002002:Brucella / Q000235:genetics* / Q000276:immunology; D002460:Cell Line; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000276:immunology; D006801:Humans; D009000:Monocytes / Q000276:immunology*; D009876:Operon; D010587:Phagocytosis
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C063842:dnaK protein, E coli