A. EMSAs of purified Rot incubated with protease reporters containing a biotin tag. Two-fold serial dilutions of Rot, starting with 4 pmol, were incubated with 40 fmol DNA. Protein-DNA complexes were separated by PAGE, and DNA probes were visualized using streptavidin DyLight. Black arrows indicate shifted probe, grey arrows indicate free probe. B. EMSA in which 2 pmol of Rot was incubated with 40 fmol of the indicated biotinylated promoter DNA with a 30- or 50-fold molar excess of non-biotinylated promoter DNA or non-biotinylated control DNA. The EMSA reaction was performed and visualized as for panel A. Black arrows indicate shifted probe, grey arrows indicate free probe. The control DNA (cDNA) used for EMSAs is the intragenic DNA between lukA and lukB.