FIG 4.

VpsT is induced when the c-di-GMP pool is increased and interacts with the rpoS promoter in the cell. Strain HX22 expressing VpsT-FLAG was transformed with plasmid pAT1662 expressing the DGC VCA0956 from the arabinose promoter. Expression of VCA0956 was induced by addition of l-arabinose to the culture medium, as described in Materials and Methods. (A) Agarose gel electrophoresis of the PCR products obtained after ChIP using an anti-FLAG MAb and the mouse MAb G3A1 IgG1 isotype control as an unrelated antibody (mock reaction). (B) Quantification of VpsT occupancy at the corresponding promoter by qPCR. Promoter occupancies are expressed as relative immunoprecipitation (IP), the amount of promoter DNA immunoprecipitated by the anti-FLAG MAb normalized by the amount immunoprecipitated in the mock reaction. Each value represents the mean of three experiments, and error bars indicate the standard deviations (*, significantly different from the uninduced culture [P < 0.05]). (C) Western blot showing that VpsT-FLAG is induced when the c-di-GMP pool is enhanced.