Figure 3.

Bending-unbending dynamics of pre-melted promoter. (A) Design of the pre-melted template with mismatches at −4 to +2 positions. (B–D) Example traces of DNA only, DNA + Rpo41, and DNA + Rpo41/Mtf1, respectively. All samples were prepared as equimolar mixture and incubated at room temperature for 1 min before vesicle encapsulation. (E) smFRET histograms of (B–D). With Rpo41, small population exists at low FRET, which is much suppressed by the addition of Mtf1. (F) Comparing the unbending rate between Rpo41 and Rpo41/Mtf1 reveals ~60-fold difference. It is 0.14 ± 0.01 s⁻¹ with Rpo41 alone and 0.0023 ± 0.0005 s⁻¹ with both Rpo41 and Mtf1. (G) Bending rate can be determined from the dwell time distribution of the low FRET state. It does not show significant change upon Mtf1 addition.