IHF binds the upstream region of papB.

A) Lane 1–2: 0 & 50 nM IHF were incubated with labeled probe and subjected to DNase I digestion. The sequence protected by IHF is marked with the dashed line on the gel and the actual sequence is shown on the right side of the figure. The solid line on the sequence and gel represent the IHF recognition site, bold bases indicate the hypersensitive sites (< on the gel) and lower case letters are not protected. The numbers indicate the position from the transcription start (+1) of papB. B) Organization of the divergent papB and papI promoter region with the IHF protected region indicated by the dashed line.