Fig. 1.

(A) Autoinducer molecules produced and detected by Vibrio species. Molecules in the left column are the CAI-1 type. HAI-1 and AI-2 are shown in the right column.B. The CqsA/CqsS quorum-sensing system of Vibrio species. Black arrows denote phosphate flow from the CqsS receptor to LuxO at low cell density. Under this condition, the Qrr sRNAs are transcribed and inhibit translation of luxR (hapR) transcripts. Thus, LuxR (HapR) proteins are not produced. At high cell density, in the presence of autoinducers, phosphate flow in the signal transduction pathway is reversed, the qrr genes are not transcribed, luxR (hapR) mRNA is translated, and LuxR (HapR) protein is produced, and it initiates the quorum-sensing response.