Figure 3.

Comparison of promoters that differ in the −12 consensus sequence. (A) The sequences of the various promoters used in this study are shown. (B) Standard activated transcription (heparin added with NTPs), using phosphorylated NtrC and ATP, was done using supercoiled templates glnHp2 (lane 1) and Hp2-M12 (lane 2). Unactivated transcription under bypass conditions (lower ionic strength, 47°C, and nucleotides; also see Fig. 1, lane 3) was done for supercoiled templates glnHp2 (lane 3) and Hp2-M12 (lane 4). Analysis of several experiments showed that the lane 1 and 2 levels were similar, whereas lane 3 gave 4- to 5-fold more RNA than lane 4. Lanes 5 and 6 are without the GpU dinucleotide in the preincubation, causing inactivation by heparin.