Figure 6.

Relationship between TF protein abundance and the number of TFBSs. (A) Ratio of TF abundance to the number of TFBSs for selected TFs in E. coli. TF abundance is derived from mass spectrum measurements (47). Grey ranges represent the ranges of TF/TFBS ratios across 19 growth conditions (excluding stationary phase growth) and circles indicate the medians for each TF. Horizontal lines indicate the TF/TFBS ratios of 2, 5 and 10. For graphic clarity, only selected TFs are shown for TFs with less than 5 binding sites. The full set of TF data is provided in Supplementary Table S3. (B) Underestimation of TFBSs. TFBS numbers from the high throughput (HT) dataset analyzed by RegulonDB (9) are compared to the TFBS numbers curated from the experimental dataset of regulonDB (see Supplementary materials for details). Each circle represents one TF among the 36 with HT data. Colors of circles correspond to autoregulation modes.