FIG. 3.

In vitro transcription of lac and hybrid-lac promoters with wild-type RNAP (A) or αΔ235 mutant RNAP (B). The upstream sequences of the hybrid promoters and their junction with the lac core promoter (at position −37) are shown in Fig. 5. Transcripts were separated on 5% acrylamide–7 M urea gels, and hybrid promoter, lacUV5, and vector-encoded promoter RNA I transcripts are indicated. Duplicate samples are shown in panel A. The RNAP concentrations were 2 nM (A) and 8 nM (B). Plasmid templates for transcription were as follows: lac, pRLG1821; rrnB P1-lac, pRLG1820; RNA II-lac, pRLG940; merT-lac, pRLG941; rrnB P2-lac, pRLG942; and lacUV5, pRLG593.