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. 2011 Jan 7;193(6):1369–1376. doi: 10.1128/JB.00288-10

FIG. 6.

FIG. 6.

Identification of CRP-dependent transcription start sites. Numbering is relative to the tibD initiating codon. (A) Primer extension was used to map the transcription start sites of tibDBp in wild-type and crp::kan reporter strains carrying the natural CRP binding site, tibDBo, or the mutagenized binding sites, tibDBo1 and tibDBo2. Lanes T, A, C, and G contain dideoxy chain-terminated sequencing ladders produced with the same primer as the primer extension reactions. The band running across all lanes near −131 is an artifact. (B) Sequences of the tibDB promoter region and the mutagenized binding sites tibDBo1 and tibDBo2. Overlines and underlines indicate the extent of CRP DNase I footprints. The inverted repeat within the binding site is shown in bold. Filled arrows and bold type denote the positions of the three transcription start sites. The weight of each line/arrow reflects the relative proportions of each primer extension product. The distance between the center of the CRP binding site (unfilled arrow) and each transcription start site is shown in brackets.