Mechanical Regulation of Chemotaxis Signaling by Bacterial Mechanosensors

Project Abstract Bacterial infections and chronic diseases cause significant healthcare costs each year. However, the mechanisms underlying the formation of bacterial communities, such as biofilms and swarming colonies, remain poorly understood. Community formation by motile bacteria is typically initiated when a cell senses its attachment to a surface, usually by utilizing the flagellum as a tactile (mechanosensor) sensor. The flagellar stator, which rotates the flagellum, has been shown to sense mechanical obstruction upon adhesion to a surface and remodel in response. The remodeled stator delivers higher mechanical force to rotate the flagellar rotor. While the stator has been widely implicated in surface sensing and biochemical signaling, the mechanisms are not understood. Understanding these mechanisms is critical for developing innovative strategies to prevent bacterial community formation. The PI's preliminary findings have uncovered a link between chemotaxis signaling and stator mechanosensing. Therefore, the objective of the proposed work is to explain the mechanistic basis for this link and reveal fundamental insights into mechanotransduction in bacteria. The long-term goal is to develop clinically useful strategies to prevent chronic bacterial infections and antibiotic resistance. The proposed projects will quantitatively measure the mechanical stimuli on the flagella as the cell's extracellular environment changes. Investigations will determine the correlation between mechanical stimuli and the stator's role in maintaining homeostasis in the output of the chemotaxis signaling network, which enables the cell to transition to surface- adapted lifestyles. The mechanism by which the stator amplifies force delivered to the rotor to adapt the chemotactic output will be determined to explain the basis for its mechanosensitive functions. Finally, the mechanism by which the cell globally couples mechanosensitive flagellar functions will be explained. The proposed work will employ advanced biophysical techniques such as optical tweezers, single-motor mechanical stimulation assays, single-molecule fluorescence measurements, molecular biology tools, and stochastic modeling. It is expected that the results will help establish a paradigm for understanding how bacteria integrate signals from mechanosensors to target suitable niches. Quantification of the extracellular mechanical stimuli typically encountered by the cells is anticipated to assist researchers in interpreting motility results across diverse bacterial species.