VirG, PhoB, and OmpR are positive regulators of the virulence, phosphate, and osmolarity regulons, respectively. Their target genes are attended with one or more significant blocks of similar 6-bp sequences in their regulatory regions. The distance between the block(s) and transcriptional start site varies with the target genes, but the blocks are located in a similar manner phase-specific to the promoter sequences. On the basis of these facts, we offer a novel model of transcriptional activation common to these regulators.