FIGURE 4.

The CpxR protein binds to the mar promoter. A, DNase I footprinting analysis of the wild-type mar promoter with ³²P-labeled probe for the noncoding strand and increasing amounts of CpxR-His₆ protein (100 and 200 pmol). Products were subjected to polyacrylamide DNA sequencing electrophoresis, and the bands were detected by autoradiography. The right bracket corresponds to the CpxR binding site, and the sequence represents the DNA region protected by CpxR-His₆ protein. Red boxes are the CpxR box sequence. B, DNA sequence of the mar promoter region. The underlines correspond to the CpxR-protected region. Sequences in red resemble a reverse consensus CpxR box. Double arrows indicate the putative −35 and −10 sequences, respectively. The nucleotide A in purple with arrow is the transcription start site (+1). Sequences in blue and green are the marbox and MarR binding site, respectively. Numbering in A and B is from the +1.