FIG. 1.

Principal components of the c-di-GMP signaling pathway. C-di-GMP is synthesized by GGDEF domain proteins, which are di-guanylate cyclases. Degradation of c-di-GMP occurs through c-di-GMP-specific PDEs. These enzymatic activities are present in the unrelated EAL and HD-GYP domains and degrade c-di-GMP to pGpG and GMP, respectively. Subsequently, c-di-GMP binds to downstream proteins or RNA receptors (17, 20). c-di-GMP thereby stimulates sessility and inhibits motility and virulence properties required for acute infection.