FIG 2.
VraSRSS directly regulated the expression of YvqFSS and itself in SS2. (A) The yvqFSS, vraSSS, and vraRSS genes formed an operon, as determined by RT-PCR. An RNA sample that was not reverse transcribed served as a negative control. (B) Expression levels of yvqFSS in the WT, ΔvraSRSS, and complemented strains were measured by qRT-PCR. qRT-PCR expression values are shown as the means plus standard deviations (error bars) from at least three independent experiments. The unpaired two-tailed Student's t test was used for statistical analysis (ns, P > 0.05; ***, P < 0.001). (C) An EMSA showing VraRSS binding to the promoter region of the yvqFSS operon. The purified VraRSS fusion protein was added to each reaction mixture at different concentrations. DNA probes containing the yvqFSS operon promoter region were used at 80 ng per reaction mixture, and fragments amplified from 16S rRNA served as a negative control.