Background:The catabolite control protein A (CcpA) plays an important role in Staphylococcus aureus virulence, biofilm formation, and central metabolism. Results: Phosphorylation of CcpA negatively affects its DNA binding activity and thus the expression of its target genes. Conclusion: CcpA activity is modulated by Stk1 phosphorylation. Significance: This study highlights that phosphorylation of CcpA represents a novel regulatory control mechanism for this major transcriptional factor.

The Staphylococcus aureus autoinducer-2 (AI-2) producer protein LuxS is phosphorylated by the Ser/Thr kinase Stk1 at a unique position, Thr14. The enzymatic activity of the phosphorylated isoform of LuxS was abrogated compared to that of nonphosphorylated LuxS, thus providing the first evidence of an AI-2-producing enzyme regulated by phosphorylation and demonstrating that S. aureus possesses an original and specific system for controlling AI-2 synthesis.