Evidence for multiple OmpR-binding sites in the upstream activation sequence of the ompC promoter in Escherichia coli: a single OmpR-binding site is capable of activating the promoter.

We present experimental evidence for the existence of multiple activator-binding sites in the upstream sequence of the ompC promoter, the expression of which is activated by the positive regulator OmpR in response to the osmolarity of the medium. We also found that a single OmpR-binding site can activate the ompC promoter, providing that the binding site is close and placed stereospecifically with respect to the canonical-35 and -10 regions.