FIG 6.

Bile salts disrupt VqmA-DPO-mediated signal transduction and promote V. cholerae virulence. (A) pvqmR-lacZ activity in ΔvqmA Δtdh V. cholerae carrying pvqmA-FLAG following 1 h in the presence or absence of O₂, 0.5% (vol/vol) bile salts, and 0 to 25 μM DPO or combinations of all three treatments as indicated. (B) Western blot showing VqmA-FLAG for the strain in panel A following the indicated treatments. (C) Relative expression levels of vpsL and tcpA in WT and ΔvqmA V. cholerae following the designated treatments. (D) Viability of human intestinal Caco-2 cells in the absence of bacteria or following challenge by WT or ΔvqmA V. cholerae and in the presence or absence of 0.05% bile salts. Data in panels A and D represent average values from biological replicates (n = 3), and error bars represent SD. Data in panel C represent the average value from three biological replicates and two technical replicates for each sample (n = 6), and error bars represent SD. Statistical significance was calculated using a two-tailed Student t test. Asterisks are as follows: ** denotes P < 0.01, *** denotes P < 0.001, **** denotes P < 0.0001, and NS denotes P > 0.05.