A common mechanism of transcriptional activation by the three positive regulators, VirG, PhoB, and OmpR

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.