Two-component signal transduction systems, environmental signals, and virulence.

The relevance toward virulence of a variety of two-component signal transduction systems is reviewed for 16 pathogenic bacteria, together with the wide array of environmental signals or conditions that have been implicated in their regulation. A series of issues is raised, concerning the need to understand the environmental cues that determine their regulation in the infected host and in the environment outside the laboratory, which shall contribute toward the bridging of bacterial pathogenesis and microbial ecology.