title: Staphylococcus aureus ClpC is required for stress resistance, aconitase activity, growth recovery, and death.
abstract: The ability of Staphylococcus aureus to adapt to various conditions of stress is the result of a complex regulatory response. Previously, it has been demonstrated that Clp homologues are important for a variety of stress conditions, and our laboratory has shown that a clpC homologue was highly expressed in the S. aureus strain DSM20231 during biofilm formation relative to expression in planktonic cells. Persistence and long-term survival are a hallmark of biofilm-associated staphylococcal infections, as cure frequently fails even in the presence of bactericidal antimicrobials. To determine the role of clpC in this context, we performed metabolic, gene expression, and long-term growth and survival analyses of DSM20231 as well as an isogenic clpC allelic-replacement mutant, a sigB mutant, and a clpC sigB double mutant. As expected, the clpC mutant showed increased sensitivity to oxidative and heat stresses. Unanticipated, however, was the reduced expression of the tricarboxylic acid (TCA) cycle gene citB (encoding aconitase), resulting in the loss of aconitase activity and preventing the catabolization of acetate during the stationary phase. clpC inactivation abolished post-stationary-phase recovery but also resulted in significantly enhanced stationary-phase survival compared to that of the wild-type strain. These data demonstrate the critical role of the ClpC ATPase in regulating the TCA cycle and implicate ClpC as being important for recovery from the stationary phase and also for entering the death phase. Understanding the stationary- and post-stationary-phase recovery in S. aureus may have important clinical implications, as little is known about the mechanisms of long-term persistence of chronic S. aureus infections associated with formation of biofilms.
authors.affiliation: Institute of Medical Microbiology and Hygiene, Institutes of Infectious Disease Medicine, University of Saarland, Homburg/Saar, Germany.
authors.forename: Indranil
authors.initials: I
authors.lastname: Chatterjee
authors.forename: Petra
authors.initials: P
authors.lastname: Becker
authors.forename: Matthias
authors.initials: M
authors.lastname: Grundmeier
authors.forename: Markus
authors.initials: M
authors.lastname: Bischoff
authors.forename: Greg A
authors.initials: GA
authors.lastname: Somerville
authors.forename: Georg
authors.initials: G
authors.lastname: Peters
authors.forename: Bhanu
authors.initials: B
authors.lastname: Sinha
authors.forename: Niamh
authors.initials: N
authors.lastname: Harraghy
authors.forename: Richard A
authors.initials: RA
authors.lastname: Proctor
authors.forename: Mathias
authors.initials: M
authors.lastname: Herrmann
mesh_terms: D000085:Acetates; D000154:Aconitate Hydratase / Q000378:metabolism*; D001426:Bacterial Proteins / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development; D002952:Citric Acid Cycle / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000502:physiology*; D006358:Hot Temperature; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013211:Staphylococcus aureus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
chemical_list: D000085:Acetates; D001426:Bacterial Proteins; C087481:ClpC protein, Bacteria; D006360:Heat-Shock Proteins; D000154:Aconitate Hydratase