FIG. 5.

Nucleotide sequences of the dcuB (A), dctA (B), and frdA (C) promoter-operator regions. The DcuR-protected regions are highlighted in dark gray (sequences for both strands are presented, with the noncoding strand in italics), with a weakly protected region underscored with a gray bar and adjacent areas that are potentially protected but were not subject to DNase I cleavage highlighted in light gray. Hypersensitive sites are shown in bold and enclosed in small boxes. Tandemly repeated (T/A)(A/T)(T/C)(A/T)AA sequences possibly corresponding to a DcuR-binding motif are indicated with black bars or, for weak matches, striped bars. Transcription and translation start sites are in bold, and promoters and potential binding sites for Crp and Fnr are in large boxes with residues matching the Crp and Fnr consensus sequences shown in bold. The f651 stop codon is underlined. Sequences within the DcuR-binding regions closely resembling the ArcA-binding consensus [(A/T)TAATTAAC(A/T)] are boxed. Numbering corresponds to distances from the transcriptional start site. A relevant restriction site is indicated in italics.