FIGURE 6.

Model for the SuhB-mediated inverse regulation of swimming motility and biofilm formation in P. aeruginosa. Upon receipt of the proper environmental signals (such as encounter an appropriate surface or changes in medium viscosity), the free-living bacteria suppress expression of suhB and thus levels of GacA and sRNAs, RsmY and RsmZ are elevated, which in turn antagonize the regulatory activity of RsmA, resulting in a shift toward a communal biofilm-associated phenotype. In addition, the intracellular c-di-GMP levels are also increased through activation of the DGC GcbA. We hypothesize that this c-di-GMP pool may also be impacted by the action of additional DGCs or PDEs, acting as a signal to the downstream constituents of the SuhB pathway. The relationship between RetS and GacS-GacA pathway as well as titration of RsmA by RsmY and RsmZ are demonstrated in previously published data (Goodman et al., 2009). The gradient of the blue color in the bottom panel represents the switch between planktonic and biofilm lifestyles.