(a) Schematic of the intergenic region of cbdbA1624–cbdbA1625. The DNA sequence shown depicts the P5–P4 region. The long horizontal arrows above the sequence indicate inverted repeat sequences in the promoter region; the angled arrows indicate the experimentally determined transcriptional start sites; the short arrows above the inverted repeat sequences represent the putative recognition sequences of the regulator; bold and italic letters depict the consensus sequences of the −10 and −35 region predicted by the BPROM software (http://linux1.softberry.com/berry.phtml). The complete intergenic region (246 bp; P2–P1) and sub-fragments thereof (P3–P1/P5–P4) were amplified by PCR from total DNA of strain CBDB1 with primers binding in, or flanking, the intergenic region for EMSA. (b) Interaction of Strep-CbdbA1625C with the complete intergenic region (P2–P1) and the sub-fragments (P3–P1/P5–P4). EMSA was carried out in the presence (plus symbols) and absence (minus symbols) of Strep-CbdbA1625C protein. Free DNA (F) and retarded DNA–protein complexes (C1, C2, Ca) were visualized by staining with GelRed (Biotium, Hayward, CA, USA).