ABSTRACT: Bacteria often grow in association with solid surfaces, and surface colonization behaviors have a profound impact on our health. My lab is interested in how bacteria transition their physiology to achieve a surface-adapted state. We focus on a sensory transduction network that activates surface adhesion in the aquatic bacterium Caulobacter crescentus. Recognizing contact with solid surfaces plays a central role in this signaling network, and a motility machine called the flagellum serves as the primary surface sensor. We have identified dozens of genes (called fss for flagellar signaling suppressor) that regulate adhesion downstream of the flagellum. These novel surface sensing factors influence flagellar motor structure, chemotaxis behavior and metabolic processes. Mapping the roles of individual fss genes in the surface sensing network indicates that the topology of signal flux changes under different environmental conditions. We have also found that a subset of fss genes influences cellular processes that are not traditional surface responses including DNA replication and cell cycle progression. Our work illuminates new principles of how the motile to sessile transition is orchestrated in bacteria and highlights the role of network plasticity in signal transduction.
