FIG. 2.

Activation of rrnB P1 transcription by FIS in vitro. The supercoiled template contained rrnB P1 positions −154 to +50. The reaction mixtures contained 200 μM ATP and wild-type RNAP (lanes 1 and 2) or β′ Δ215–220 RNAP (lanes 3 and 4) in the absence (lanes 1 and 3) or presence (lanes 2 and 4) of FIS. The transcripts derived from the rrnB P1 promoter and from the vector-encoded RNA I promoter are indicated. Since the reaction conditions were identical in each lane and the wild-type and mutant RNAPs had similar activities on a non-FIS-activated promoter (see Materials and Methods), activation by FIS was calculated directly from the relative amounts of rrnB P1 transcripts. Only one gel is shown, but the experiment was performed multiple times with similar results.