A flagellar accessory protein links chemotaxis to surface sensing

Area of Science:

• Microbiology
• Cell Biology
• Bacterial Adhesion

Background:

• Bacteria colonize surfaces using complex signaling pathways.
• Flagellar surface sensing is crucial for activating colonization.
• Caulobacter crescentus uses a holdfast adhesin for surface attachment.

Purpose of the Study:

• Investigate the role of the FssF protein in flagellar surface sensing and bacterial adhesion.
• Elucidate the relationship between flagellar function, chemotaxis, and holdfast production.
• Determine how surface sensing networks regulate adhesion in response to flagellar disruption.

Main Methods:

• Fluorescent tagging and localization of FssF protein.
• Genetic analysis including gene deletion and epistasis experiments.
• Motility assays and chemotaxis disruption analysis.
• Investigation of key surface sensing genes (pleD, motB, dgcB) in hyperadhesive backgrounds.

Main Results:

• FssF localizes to the flagellar C-ring and is essential for proper flagellar assembly.
• Deletion of fssF causes severe motility defects due to impaired chemotaxis.
• Disruption of chemotaxis, including via fssF deletion, leads to hyperadhesion.
• Flagellar stator subunits integrate mechanical and chemical signals to regulate adhesion.

Conclusions:

• FssF is a key component of the flagellar C-ring involved in surface sensing.
• Chemotaxis disruption is a significant factor promoting bacterial hyperadhesion.
• The flagellar stator plays a central role in integrating signals to control bacterial adhesion.