Bacterial Motors and Surface Sensing

Surface-sensing precedes the establishment of many types of bacterial colonies on surfaces. Evidence suggests that surface-sensing triggers transcriptional regulation as well as post-translational signaling that promote a variety of interesting cell phenotypes. The molecular mechanisms continue to remain unclear. I will discuss how motile cells discriminate between random forces arising due to Brownian motion and those arising due to surface contact. Our recent measurements that highlight the role of the flagella (otherwise known to be involved in motility) in surface-sensing and signaling will be discussed. Single molecule experiments that explain how flagella tune the sensitivities of modules involved in well-known signaling pathways will be presented. Data indicate an indirect link between the intracellular events and the external hydrodynamic drag acting on individual flagellum, and also hint at the regulation of certain surface-dependent phenotypes by these sensitive modules. I will conclude with a brief note on how mechanically-stimulated regulatory events influence a host of important processes such as bacterial competence, which regulates the uptake of extracellular DNA.