Fig. 3

a The theoretical change in free energy needed to melt the base pairs of the promoter sequence by supercoiling density σ, from Eq. 2. b The change in the rate, K, by supercoiling density (dots) and a single exponential fit (line). c Transcription initiation rate vs the number of transcription events (green triangles) from experiment [20], the full theory Eq. 3 (red line) and the linear theory Eq. 4 (black line). The full theory had a fit R-square = 0.97 and the linear theory R-square = 0.96