FIG 6.
Specific recognition by PtvR of two palindromic sequences in the ptv promoter. (A) The diagrammatic illustration of the sequence elements (234 bp) spanning the translational start codon of ptvR. In bold are the predicted promoter motifs (−35 and −10), transcriptional start site (TSS), ribosome-binding site (RBS), and start codon of ptvR. The spacing sequences (S1, S2, and S3) are separated by two palindromic sequences (P1 and P2). (B) Biochemical binding of PtvR with the full-length ptv promoter, as determined in an EMSA. A recombinant PtvR protein was used to test binding with the Cy3-labeled ptv promoter; unlabeled promoter sequences of the ptv (Pptv) and spxB (PspxB) genes were used as competitors. (C) Sequences of the P1 and P2 elements in the ptv promoter. The 24-bp repeat sequence in P1 and P2 is underlined. The axis of P1-P2 symmetry is marked with dashed lines. (D) EMSA results with the recombinant PtvR and various segments of the ptv promoter sequence, as depicted in panel A. DNA was detected by staining with GelRed.