CifR binds to the intergenic region directly upstream of the cif-containing operon. (A) The intergenic region between the cifR and morB genes was amplified using biotinylated primers and used as a probe in EMSAs. (B) EMSA using the morB-cifR intergenic region as a probe and purified CifR. Lane 1, labeled probe; lane 2, probe and 1.15 nM CifR; lane 3, probe, 1.15 nM CifR, and a 20× molar excess of the unlabeled cold competitor; and lane 4, probe, 1.15 nM CifR, and 1 mM EBH. BT, biotinylated. (C) EMSA CifR dose response. Lane 1, probe alone; lane 2, probe and 115 pM CifR; lane 3, probe and 287.5 pM CifR; lane 4, probe and 575 pM CifR; lane 5, probe and 862.5 pM CifR; and lane 6, probe and 1.15 nM CifR. (D) EMSA EBH dose response. Lane 1, probe alone; lane 2, probe and 1.15 nM CifR; lane 3, probe, 1.15 nM CifR, and 10 μM EBH; lane 4, probe, 1.15 nM CifR, and 100 μM EBH; and lane 5, probe, 1.15 nM CifR, and 1 mM EBH.