FIG. 6.

Footprinting analyses of ArgR with the aotJ control region. The DNA fragments used were labeled at the 3′ end of the sense strand (a) and antisense strand (b) of the aotJ operator. Lanes: 1, the corresponding G+A Maxam-Gilbert sequencing ladder; 2 to 6, DNase I footprinting with decreasing concentrations of ArgR: 9, 1.8, 0.36, 0.07, and 0 pM, respectively (the protected region is indicated by a bar); 7 and 8, premethylation footprinting sequences of the unbound and bound DNA, respectively; 9 and 10, depurination footprinting sequences of unbound and bound DNA, respectively. These two forms of DNA have been separated and modified as described in Materials and Methods. Also shown are several guanine residues, which are numbered according to the description of panel c. (c) Summary of the results of the three footprinting analyses. The nucleotide sequence of a region defined by DNase I footprinting is shown and numbered accordingly. Nucleotides detected by premethylation interference footprinting are indicated by solid squares, and those detected by depurination footprinting are indicated by solid triangles. Also shown is the −35 region of P1 (Fig. 1B).