FIG 3.

VP1881 regulates its own expression in heterologous hosts. Scatterplots of relative light units (RLU) from at least 6 biological replicates from each strain of interest harboring the transcriptional fusion pBBR-P_VP1881-lux are shown. Expression of the pBBR-P_VP1881-lux fusion was analyzed in Vibrio cholerae (Vc) cells grown to the exponential phase (A) or the stationary phase (B) and in Escherichia coli (Ec) cells grown to the exponential phase (C) or the stationary phase (D) in the presence of 0.1 mM IPTG. RLU are arbitrary light units per milliliter divided by optical density at 600 nm (OD₆₀₀). The RLU value is directly proportional to the activity of the P_VP1881 promoter. The horizontal line represents the mean RLU value. Overexpression of VP1881 and its variants was achieved using expression constructs that contain an IPTG-inducible promoter. The empty plasmid pMMB67EH-Gm (pMMB) was used as a negative control. Means were compared using Brown-Forsythe and Welch ANOVA tests followed by Dunnett’s T3 multiple-comparison test. Adjusted P values of ≤0.05 were deemed statistically significant. **, P ≤ 0.01; ***, P ≤ 0.001.