PR000786 (Project)

Description:The staphylococcal respiratory regulator (SrrAB) modulates energy metabolism in Staphylococcus aureus. Studies have suggested that regulated protein catabolism facilitates energy homeostasis. Regulated proteolysis in S. aureus is achieved through protein complexes composed of a peptidase (ClpQ or ClpP) in association with an AAA+ family ATPase (typically ClpC or ClpX). In the current report, we tested the hypothesis that SrrAB regulates a Clp complex to facilitate energy homeostasis in S. aureus. Strains deficient in one or more Clp complexes are attenuated for growth in the presence of puromycin, which causes enrichment of misfolded proteins. A ?srrAB strain had increased sensitivity to puromycin. Epistasis experiments suggested that the puromycin sensitivity phenotype of the ?srrAB strain was a result of decreased ClpC activity. Consistent with this, transcriptional activity of clpC was decreased in the ?srrAB mutant and overexpression of clpC suppressed the puromycin sensitivity of the ?srrAB strain. Genetic studies suggested that phosphorylated SrrA is required to influence puromycin resistance. ClpC positively influenced respiration in association with ClpP. ClpP was also required for optimal fermentative growth, whereas ClpC was dispensable. Metabolomics studies demonstrated that intracellular metabolic profiles of the ?clpC and ?srrAB mutants are distinct from 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.