Flagellar motor remodeling during swarming requires FliL

Area of Science:

• Microbiology
• Bacterial Motility
• Molecular Biology

Background:

• FliL is a component of bacterial flagella, crucial for motility.
• Its role varies from essential to conditional, impacting swarming behavior.
• Swarming requires increased flagellar motor torque due to surface-associated forces.

Purpose of the Study:

• To identify and characterize the conserved function of FliL in bacterial swarming.
• To investigate the mechanism by which FliL influences flagellar motor parameters during swarming.
• To explore the interaction between FliL and other flagellar components.

Main Methods:

• Comparative analysis of FliL function in Escherichia coli, Bacillus subtilis, and Proteus mirabilis.
• Assessment of bacterial cell speed and flagellar motor bias during swarming.
• Complementation studies using fliL genes from different bacterial species.
• Protein interaction analysis focusing on FliL and FliF.

Main Results:

• FliL is essential for "motor remodeling" in E. coli, B. subtilis, and P. mirabilis during swarming.
• Motor remodeling involves increased cell speed and suppressed tumbling (skewed motor bias).
• The swarming-associated function of FliL is conserved across bacterial phyla, as demonstrated by complementation studies.
• FliL interacts with the RBM-3 domain of the MS-ring protein FliF.

Conclusions:

• FliL plays a conserved role in enhancing bacterial swarming motility through flagellar motor remodeling.
• This remodeling optimizes bacterial movement on surfaces by increasing speed and directional persistence.
• The interaction between FliL and FliF is critical for these observed phenotypes.