DNase I footprinting assays. Both the coding and noncoding strands of the promoter DNA fragments were generated by PCR. Labeled DNA probe was incubated with various amounts of purified Zur (lanes 1, 2, 3 and 4 contained 0, 2.5, 5 and 10 pmol, respectively). After partial digestion with DNase I, the resulting fragments were analyzed with 6% acrylamide sequencing gel. Lanes C, T, A and G represented the Sanger sequencing reactions. On the right side, the Zur protected regions were labeled with bold lines, and the footprint sequences were shown below. Positive and minus numbers flanking the bold lines indicate the nucleotide positions downstream and upstream the transcriptional site (taken as +1), respectively.