Figure 4. Transcriptional regulation roles and DNA-binding activities of VapBC10 proteins.

(A) Effects of VapBC10 components on the transcriptional activity of P_vapBC10 measured by β-galactosidase activity assay. The structures of lacZ reporter plasmids are shown in the left panel, and the β-galactosidase activities are presented in the right panel. The values are the averages of three independent experiments. Error bars represent standard deviation. (B) EMSAs for the binding of VapBC10 components to the P_vapBC10 DNA. A 296-bp DNA fragment P, containing P_vapBC10, was prepared by PCR using the primers P_vapBC10-E1 and P_vapBC10-E2. The labeled fragment P was incubated with final concentrations of VapB10 (lanes 1–8) or with VapC10-His₆ (lanes 9–15) as indicated at the bottom panel. Specific and nonspecific binding events are shown using 1 µM of the unlabeled fragment P (lane 7) or P_BAD (lane 8) obtained from pJS298 by PCR amplification using the primers P_BAD-F and P_BAD-R. P indicates unbound DNA and arrows shifted DNA-protein complexes. - symbolizes the absence of the competitor DNA. (C) EMSAs for the binding of the complex VapBC10 to the P_vapBC10 DNA. The labeled fragment P was incubated with increasing concentrations of the VapBC10 complex.