Flagellar Stators Stimulate c-di-GMP Production by Pseudomonas aeruginosa

Area of Science:

• Microbiology
• Bacterial Physiology
• Molecular Biology

Background:

• Flagellar motility is crucial for bacterial surface attachment and biofilm development.
• Cyclic diguanylate (c-di-GMP) is a key second messenger regulating motility and biofilm formation in bacteria like *Pseudomonas aeruginosa*.
• c-di-GMP influences flagellar motor function, including stator localization (MotAB, MotCD).

Purpose of the Study:

• To investigate the bidirectional relationship between flagellar stators and c-di-GMP levels.
• To elucidate the molecular mechanism by which flagellar components impact c-di-GMP synthesis.
• To understand how this interaction contributes to the regulation of bacterial motility and biofilm formation.

Main Methods:

• Co-immunoprecipitation assays to detect protein-protein interactions.
• In vitro enzyme activity assays to measure diguanylate cyclase function.
• Bacterial genetics and motility assays to assess the physiological impact of stator-c-di-GMP interactions.

Main Results:

• The flagellar stator MotC physically interacts with the diguanylate cyclase SadC.
• This interaction between MotC and SadC stimulates SadC's enzymatic activity.
• A positive-feedback model is proposed where disengaged MotCD stators promote c-di-GMP production.

Conclusions:

• Flagellar motor components, specifically MotC, can directly regulate c-di-GMP synthesis.
• This interaction establishes a feedback loop that reinforces biofilm formation by increasing c-di-GMP levels.
• The findings reveal a novel communication pathway between the flagellar machinery and c-di-GMP signaling, crucial for switching between motility and biofilm lifestyles.