Fig. 4.

Response of V. cholerae and V. harveyi wild-type CqsS and CqsS mutants to different CAI-1 type molecules. The CqsS-dependent quorum-sensing responses to different CAI-1 type molecules were measured by assaying activation of bioluminescence expression in wild-type V. harveyi (A), wild-type V. cholerae (B), V. cholerae carrying CqsS C170F (C) and V. harveyi carrying CqsS F175C (D). C8-CAI-1, closed circles; Ea-C8-CAI-1, closed squares; CAI-1, open circles, Ea-CAI-1, open squares. See Fig. 1A for the structures of the different molecules. Representative data from at least three independent experiments are shown. See Table 1 for EC₅₀ values for each receptor/ligand combination. RLU denotes relative light units.