Static bend of DNA helix at the activator recognition site of the ompF promoter in Escherichia coli.

Expression of the ompF gene coding for a major outer membrane protein of Escherichia coli is regulated by osmolarity of the medium. The ompF expression is controlled by a transcriptional activation mechanism which requires the ompR gene product acting on a region located upstream from the canonical -35 and -10 regions of the ompF gene. Evidence is presented that the upstream region of the ompF promoter contains a static bend of DNA having two sets of oligo (dA X dT) tracts with periodical spacing. It was demonstrated that the bending region overlaps with the recognition site for the activator protein, OmpR.