The Staphylococcus aureus autoinducer-2 synthase LuxS is regulated by Ser/Thr phosphorylation

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Staphylococcus aureus utilizes quorum sensing (QS) for community behavior.
• Autoinducer-2 (AI-2) is a key signaling molecule in bacterial QS systems.
• The LuxS enzyme synthesizes AI-2 in S. aureus.

Purpose of the Study:

• To investigate the regulation of Staphylococcus aureus LuxS enzyme activity.
• To determine the role of post-translational modifications, specifically phosphorylation, in LuxS function.
• To elucidate the specific mechanism controlling AI-2 synthesis in S. aureus.

Main Methods:

• Phosphorylation assays using purified LuxS and Stk1 kinase.
• Enzymatic activity assays of phosphorylated and non-phosphorylated LuxS.
• Site-directed mutagenesis to identify phosphorylation sites.

Main Results:

• Staphylococcus aureus LuxS is phosphorylated by the Ser/Thr kinase Stk1 at threonine residue 14 (Thr14).
• Phosphorylation of LuxS by Stk1 abrogates its enzymatic activity.
• This is the first demonstration of AI-2 synthesis regulation via enzyme phosphorylation.

Conclusions:

• S. aureus possesses a unique and specific system for controlling AI-2 synthesis.
• Phosphorylation of LuxS by Stk1 represents a novel regulatory mechanism for AI-2 production.
• This finding provides insights into quorum sensing regulation in S. aureus.