FIGURE 6.

Effect of Irr on Fur binding to the irr gene promoter in vitro. DNase I footprinting analysis was carried out using irr promoter DNA. The binding reactions contained either no protein (lane 1), 10 nm Fur alone (lane 2) or Fur titrated with increasing concentrations of Irr (lanes 3–8). The Irr concentrations used 0, 25, 150, 250, 500, 1000, or 2000 nm. DNA was radiolabeled at the 5′-end of the non-template strand, and thus, the 3′-end is at the top of the gel. The open arrowhead indicates a DNase I-hypersensitive site caused by Fur binding. The closed arrowheads represent the DNase I-hypersensitive sites caused by Irr binding.