Figure 6.

Initiation Pausing on the Path to Promoter Escape

(A) Promoter DNA fragment used.

(B) Time trace showing FRET changes consistent with escape. We added 200 μM ATP and 100 μM UTP, GTP, and CTP. The escape event was marked by the sharp FRET decrease from the maximum FRET state to the baseline (∼88 s). No significant E^∗ change is observed after escape during the remaining ∼100 s.

(C) Common behaviors consistent with escape. Top panels: example of escapes (marked by black arrowhead) preceded by a clear abortive cycle (green highlight). Bottom panels: examples of escapes preceded by a pause at E^∗∼0.37 (blue highlight).

(D) Dwell-time distribution of pauses in (C) (n = 130).

(E) Time trace showing three abortive cycles (green highlight) followed by a cycle consistent with escape.

See also Figure S4.