Fig. 5

DNA-binding properties of CtcS targeting the ctcR promoter region. a Purified CtcS analyzed by SDS-PAGE. b EMSAs of CtcS binding to the ctcS-ctcR intergenic region. The 148 bp FAM-labelled DNA fragment of the intergenic region was incubated with increasing concentrations of CtcS protein (lanes 2–4; lanes contain 10, 20, 40 pmol CtcS, respectively). Lane 1, negative control without CtcS; lane 5, 40 pmol CtcS with labeled and unlabeled probes. The shifted bands are indicated by arrows. c DNase I footprinting of CtcS in the ctcS-ctcR intergenic region. The sequence around the protected region is indicated below the electrophoregrams, and the palindromic sequence of the protected region is indicated with red arrows. d Nucleotide sequence of ctcS-ctcR intergenic region. The two CtcS-binding sites are underlined and the direct repeats are marked with red in bold. The bent arrows indicate the transcription orientation of ctcS and ctcR, and the possible − 10 and − 35 regions are indicated with green and blue box, respectively