FIG. 6.

Features of the NtcA-regulated hetC, nrrA, and devB promoters used in this study. The depicted sequences (noncoding strands) are included in the DNA fragments of the corresponding promoters used throughout this study (see Materials and Methods for details). The locations of the sequence signature of the NtcA binding site, the −10 box, and the tsp are as described by Muro-Pastor et al. (36) for hetC, Muro-Pastor et al. (35) for nrrA, and Fiedler et al. (16) for devB. Arrows point to the positions marked in potassium permanganate footprinting in the promoters of hetC and devB (Fig. 5).