Fig 3.

Effect of NtcA and HetR on in vitro transcription from the two promoters of the devB gene. (A) Diagram of the DNA fragments (a to c) used in in vitro transcription assays. Approximate locations of the TSPs at positions −454 and −704, the putative −10 promoter boxes, and a consensus NtcA-binding site are indicated. (B) In vitro runoff transcription assays were performed with the three DNA fragments of the devB genomic region represented in panel A in the presence or absence of NtcA plus 2-OG and HetR. NtcA (130 nM), supplemented with 2-OG (0.6 mM) and HetR (28 nM) as indicated, was incubated with the DNA fragment before addition of RNAP (27 nM) and SigA (88 nM). Arrowheads indicate the full transcript encompassing positions from the corresponding TSP to the end of the DNA fragment used. Size markers (in nucleotides) are indicated to the left.