Figure 2.
CO-dependent footprinting of the cooF promoter region with purified CooA. A 294-bp fragment bearing the CooA binding site upstream of cooF was used as a substrate for a DNase I protection experiment, either in the presence of CO or in the absence of CO. All reactions were performed anoxically under reducing conditions. The numbers at the top reflect the nM concentration of CooA in each reaction. The bracket on the right indicates the protected region, which encompasses the CooA-binding site identified previously (15). The numbers next to the bracket indicate the position of the protected bases relative to the CO-regulated cooF transcription start site (15).