title: Participation of the molecular chaperone DnaK in intracellular growth of Brucella suis within U937-derived phagocytes.
abstract: In the intracellular bacterium Brucella suis, the molecular chaperone DnaK was induced under heat-shock conditions and at low pH. Insertional inactivation of dnaK and dnaJ within the dnaK/J locus led to the conclusion that DnaK, but not DnaJ, was required for growth at 37 degrees C in vitro. Viability of the dnaK null mutant was also greatly affected at low pH. Under conditions allowing intracellular multiplication, the infection of U937-derived phagocytes resulted in long-lasting DnaK induction in the wild-type bacteria. In infection experiments performed with both mutants at the reduced temperature of 30 degrees C, the dnaK mutant of B. suis survived but failed to multiply within U937 cells, whereas the wild-type strain and the dnaJ mutant multiplied normally. Complementation of the dnaK mutant with the cloned dnaK gene restored growth at 37 degrees C, increased resistance to acid pH, and increased intracellular multiplication. This is the first report of the effects of dnaK inactivation in a pathogenic species, and of the temperature-independent contribution of DnaK to intracellular multiplication of the pathogen B. suis.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, France. liautard@crit.univ-montp2.fr
authors.forename: S
authors.initials: S
authors.lastname: Köhler
authors.forename: J
authors.initials: J
authors.lastname: Teyssier
authors.forename: A
authors.initials: A
authors.lastname: Cloeckaert
authors.forename: B
authors.initials: B
authors.lastname: Rouot
authors.forename: J P
authors.initials: JP
authors.lastname: Liautard
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D002002:Brucella / Q000254:growth & development*; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018832:Molecular Chaperones / Q000502:physiology*; D016254:Mutagenesis, Insertional; D010586:Phagocytes / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; C063842:dnaK protein, E coli