The bacterial second messenger cyclic bis-(3′-5′)-diguanylic acid (c-di-GMP) regulates diverse Gram-negative bacterial virulence functions. The pathways that control, or are controlled by, c-di-GMP suggest that c-di-GMP signaling systems may encompass potential drug targets. It is presently undetermined, however, whether up-or down-modulation of c-di- GMP signaling would be the desired therapeutic state. We addressed potential drug target ...