FIG 2 .
TfoS directly regulates the sRNA TfoR to indirectly regulate tfoX translation. (A) Miller assay for V. cholerae WT and TfoS mutant strains containing either a PtfoR-transcriptional (TX) fusion or a tfoX-translational (TL) fusion to the endogenous copy of lacZ in the chromosome. (B) EMSAs using 0.5 nM the indicated probe and purified GST-tagged cytoplasmic TfoS protein. The amount of protein added increases from left to right, as indicated by the black triangles above the panels, and corresponds to final concentrations of 0, 80, 160, and 320 nM protein. Data in panel B are representative of at least three independent EMSAs. (C) Transformation of WT, TfoS mutant, and TfoR mutant strains, each containing pGST-′TfoS and grown in M9 plus GlcNAc in the presence of 1 µM IPTG with 500 ng of a PCR product conferring kanamycin resistance. White bars in panel C indicate no transformants were obtained, and those data are presented at the limit of detection. Statistical comparisons were made by Student’s t test. Data from panels A and C are shown as means ± SD and are from at least three independent biological replicates. **, P < 0.01; ***, P < 0.001.