Fig. 2
The pause characteristics are a function of the downstream DNA promoter sequence at the + 6 position and of the 5′-RNA end nature. a Probability density distribution for the ΔtITC6 for the RP complexes behaving as in Fig. 1c. The dashed line is a single-exponential fit from a MLE. Inset: Log-lin representation of the same data. Experimental conditions: 500 µM ApA starting substrate, 80 µM all NTPs. b ΔtITC6 lifetime extracted from single exponential MLE fit similar to a for different promoter/starting substrate conditions (as indicated in the panel), different NTP conditions, i.e., all NTPs for WT/ApA (yellow) and ITC11 (Supplementary Fig. 1a) for all others, and different NTP concentrations (Supplementary Table 1). In the ATP-initiated reactions, we did not use NTP concentration below 5 µM to prevent potential misincorporations of ATP (used at 500 µM for initiation purposes)69. On the right-hand side is indicated the mean ± SD of kITC6 for each promoter/starting substrate condition. c Probability to reach the fully scrunched (FS) FRET level in a single attempt (Fig. 1c). The solid lines are fits to a binding isotherm of the form \(p\left( \mathrm{{NTP}} \right) = P_{\rm max,esc} \times \left[ \mathrm{{NTP}} \right]/(\left[ \mathrm{{NTP}} \right] + K_{\mathrm{{NTP}}})\). The error bars are 95% confidence intervals. d KNTP and Pmax,esc extracted from c. Error bars are 1 SD extracted from the fit
