Fig. 5.

The effect of pause displacement on pause suppression. A. Both classes of templates contained P_L-putL (wild type or mutant G), and this was followed either by the U-rich pause in its normal position ("proximal pause"), or by the same pause displaced by insertion of 27nt ("distal pause"). Four transcription conditions were used: putL⁺ template with WT RNAP (squares), putL⁻ template with WT RNAP (triangles), putL⁺ template with Y75N RNAP (circles), and putL⁻ template with Y75N RNAP (diamonds). Templates were transcribed for various times, and the fraction of paused ECs was plotted as function of time. B. (Top) Templates with 1 to 12 bp inserted immediately downstream of the end of putL were transcribed and sampled 1 and 3 min after the initiation of transcription. (Bottom) Quantitation of the amount of transcript paused at 3 min. C. The effect of the U-rich pause on terminator readthrough. Templates containing WT or mutant putL sites followed by WT or altered pause sites and the T_R′ terminator were transcribed for 3 min, and the fraction of runoff ECs was calculated (bottom).