Characterization of StyR-P and IHF binding to the URE. DNase I protection assay in which a DNA fragment extending from -145 to -8 (Top Strand) of the PstyA promoter was incubated with different amounts of IHF and/or StyR-P proteins prior to DNase I digestion. Numbering refers to PstyA transcription start site. Solid brackets indicate the regions showing specific protection by StyR-P; dashed bracket indicates the region showing specific protection by IHF. Triangles indicate bands that are distinctive of the protection pattern obtained in the absence of IHF (open triangles indicate hypersensitive sites). M, Maxam and Gilbert sequencing reactions (A+G); IHF concentrations: lanes 1, 8, and 9, no IHF added; lanes 2 to 7, 4.0 μM; lanes 10 to 15, 0.5 μM, 1.0 μM, 2.0 μM, 4.0 μM, 8.0 μM and 8.0 μM, respectively. StyR-P concentrations: lanes 7, 8, and 15, no StyR-P added; lanes 1 to 6, 8.0 μM, 8.0 μM, 4.0 μM, 2.0 μM, 1.0 μM and 0.5 μM, respectively; lanes 9 to 14, 4.0 μM.