Positional distribution of CRP site centers relative to the (predicted) transcription start. (A) Known CRP sites (from RegulonDB):(blue) activator sites, (red) repressor sites, (black) unknown. (B) Candidate CRP sites found in the present search with position relative to transcription start inferred from the closest σ70 candidate binding site. Note the significant peaks of the distribution at -62, -72, -82, -93, and -103, that is, Class I positions. Note also the significant peaks at -48 and -29 positions, which we interpret as repressor sites. The proposed functional classification is (blue) activator sites, (red) repressor sites, (black) unknown. (C) Same as B with the addition of putative Class II CRP sites found in the composite CRP-σ70 site search. The green line represents the estimated background distribution.
