FIG. 2.

Positions and alignment of CfaD/Rns binding sites. (A) CfaD/Rns binding sites are represented as filled rectangles. The position of the rectangle above or below the line indicates whether the conserved sequence occurs on the coding or noncoding strand, respectively. Numbering is relative to the transcription start sites, which are represented by wavy arrows. ETEC promoters rnsp, cooBp (CS1 pilus), cfaAp (CFA/I pilus), and cexEp are activated by Rns or CfaD. In contrast, nlpA is common to both ETEC and K-12 strains and its promoter, nlpAp, is repressed by Rns or CfaD. It is not known if the occupancy of binding site yicSo affects expression from yicS. (B) Optimal alignment of the conserved core sequence of each CfaD/Rns binding site. Although CfaD and Rns may contact DNA beyond the nucleotides shown, the greatest sequence conservation occurs within this core of 12 bp.