Figure 5.

Binding sequence of GadX on btuB promoter. (A) The 461-bp DNA fragment containing btuB promoter was labeled at 5' end with ³²P, incubated with 0, 16, 24, 32, or 40 pmoles of MalE-GadX, and then subjected to DNase I footprinting. A Sanger's DNA sequencing reaction was also done on the 461-bp fragment to reveal GadX binding sequences. All reactions were electrophoresed in a 6% urea-acrylamide gel, and the DNA bands were detected by autoradiography. The GadX bound regions are indicated with vertical lines, and the binding sequence of GadX are shown. (B) Sequence of the btuB promoter region. The boxed sequences are GadX binding sequences determined by the DNase I footprinting. The shaded sequences are -10 and -35 regions of the btuB promoter. The initiation codon of btuB is underlined.