The ClpCP Complex Modulates Respiratory Metabolism inStaphylococcus aureusand Is Regulated in a SrrAB-Dependent Manner
ABSTRACTThestaphylococcalrespiratoryregulator (SrrAB) modulates energy metabolism inStaphylococcus aureus. Studies have suggested that regulated protein catabolism facilitates energy homeostasis. Regulated proteolysis inS. aureusis achieved through protein complexes composed of a peptidase (ClpQ or ClpP) in association with an AAA+family ATPase (typically, ClpC or ClpX). In the present report, we tested the hypothesis that SrrAB regulates a Clp complex to facilitate energy homeostasis inS. aureus. Strains deficient in one or more Clp complexes were attenuated for growth in the presence of puromycin, which causes enrichment of misfolded proteins. A ΔsrrABstrain had increased sensitivity to puromycin. Epistasis experiments suggested that the puromycin sensitivity phenotype of the ΔsrrABstrain was a result of decreased ClpC activity. Consistent with this, transcriptional activity ofclpCwas decreased in the ΔsrrABmutant, and overexpression ofclpCsuppressed the puromycin sensitivity of the ΔsrrABstrain. We also found that ClpC positively influenced respiration and that it did so upon association with ClpP. In contrast, ClpC limited fermentative growth, while ClpP was required for optimal fermentative growth. Metabolomics studies demonstrated that intracellular metabolic profiles of the ΔclpCand ΔsrrABmutants were distinct from those of the wild-type strain, supporting the notion that both ClpC and SrrAB affect central metabolism. We propose a model wherein SrrAB regulates energy homeostasis, in part, via modulation of regulated proteolysis.IMPORTANCEOxygen is used as a substrate to derive energy by the bacterial pathogenStaphylococcus aureusduring infection; however,S. aureuscan also grow fermentatively in the absence of oxygen. To successfully cause infection,S. aureusmust tailor its metabolism to take advantage of respiratory activity. Different proteins are required for growth in the presence or absence of oxygen; therefore, when cells transition between these conditions, several proteins would be expected to become unnecessary. In this report, we show that regulated proteolysis is used to modulate energy metabolism inS. aureus. We report that the ClpCP protein complex is involved in specifically modulating aerobic respiratory growth but is dispensable for fermentative growth.