Figure 8. Class I activation by CRP occurs exclusively through stabilization.

(A) $t_{+}$ and $t_{-}$ were measured for promoters containing variants of the consensus RNAP binding site as well as a CRP binding site centered at −60.5 bp. Because the consensus RNAP site is 1 bp shorter than the RNAP site of the lac* promoter, CRP at −60.5 bp here corresponds to CRP at −61.5 bp in Figure 5. (B) $n=18$ data points obtained for the constructs in panel A, overlaid on the measurements from Figure 5B (gray). The value $t_{\mathrm{sat}}=15.1$ a.u., inferred for Figure 5C, is indicated by dashed lines. (C) Values for $\beta$ inferred using the data in Figure 5 for the 10 CRP positions that exhibited greater than 2-fold inducibility; $\beta$ values at the two other CRP positions (−66.5 bp and −76.5 bp) were highly uncertain and are not shown. Error bars indicate 68% confidence intervals.