[i] The first column reports the ratio of expression between the strong-TATA basal promoters and the weak-TATA and the no-TATA basal promoters. The second column reports the slope of the line fitted on the expression of identical clones in the strong-TATA and weak-TATA libraries, and in the strong-TATA and no-TATA libraries. The last column reports the calculated relative affinity of RNAP for the strong versus weak TATA and for the strong versus the no TATA (with 95% C.I.), after having estimated the ΔG of RNAP–DNA binding with the thermodynamic model.