Probability of TF binding site overlap.

<p>Binding sites are defined as an interval of nucleotides from the 5×10⁶ bp <i>E. coli</i> genome covered by a TF upon binding. Two binding sites sharing one or more nucleotides are considered to be overlapping, independently of which strand the TFs bind. Binding sites overlapping more than one binding site are classified according to the site with the most overlap. Notice that the probabilities of “Repressor overlaps activators” and “Activator overlaps repressor” are not identical despite the number of overlapping activator and repressor binding sites in a region being fixed. For example, there are many more activators than repressors binding upstream of −100 bp, which results in a higher probability for a repressor to overlap with an activator in this region than vice versa.