Fig. 4.

Map of cotranscriptional folding events. The average computed position of the last nucleotide transcribed at the specified event is indicated (solid diamonds; SEM ±~1 nt, approximately equal to the symbol width), beginning with the resumption of transcription at the 5′-U, ending with termination or run-through and roadblock arrest. The numbers of nt associated with folding elements are indicated. Adenine-bound aptamer folding (blue diamond, average position; blue arrows, sampled individual observations) occurred between P1 and complete terminator transcription. For forces below 9 pN (5.8 pN; 8.1 pN), the terminator hairpin (underlined) was observed to begin folding (light pink diamond) before the termination position (dark pink diamond; transcript release). At higher forces (10.4 pN), the average folding position differed between traces that terminated (T, orange diamond) or ran through (R, orange diamond), occurring too late in the latter to produce successful termination. See Table S2 for additional details.