FIG. 3.

VieS affects the level of vieA expression. (A) V. cholerae wild-type (WT) and ΔvieS strains were grown in MOPS minimal medium supplemented with 25 mM Asn, Arg, Glu, and Ser (NRES) and 0.75 mM KH₂PO₄ to late exponential phase. Total RNA was isolated, and a cDNA pool was prepared by random-priming RT-PCR. Quantitative RT-PCR was used to quantitate the level of vieA transcript using gene-specific primers. Results were normalized to an internal control, rpoB, and presented as quantities relative to that for the wild type. The mean and standard deviation from technical replicates are shown. An independent experiment gave similar results. (B) VieA mutant strains were also assayed for vieA transcript level upon stimulation with NRES as described for panel A. The VieA ΔHTH (HTH) mutant was assayed along with the PDE E170A (PDE) mutant and the phosphoreceiver D52A mutant (D52A). The mean and standard deviation for three biological replicates are shown.