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. Author manuscript; available in PMC: 2010 Jan 1.
Published in final edited form as: Methods. 2008 Oct 24;47(1):13–24. doi: 10.1016/j.ymeth.2008.10.018

Fig. 3.

Fig. 3

In vitro transcription from the multicopy plasmid vector pRLG770 [32] containing the E. coli S10 promoter (−100 to +50). (A) Single round transcription reactions were carried out in buffer containing different final concentrations of NaCl. Complexes were preformed with 10 nM RNAP and 1 nM plasmid DNA at 30°C, followed by addition of the competitor heparin (to 10 μg/ml) and NTP substrates. Duplicate samples were carried out at each of the indicated NaCl concentrations, and products were separated on a 5% acrylamide-7M urea, 1X TBE gel. Transcription products from the S10 promoter (~~190 nt), and from the vector-encoded RNA I promoter (110nt) are indicated. (B) Data from (A) were quantified using ImageQuant software. Average transcription levels from duplicate lanes are plotted relative to that from the S10 promoter at the highest NaCl concentration (30 mM). Filled circles: S10 promoter transcripts; open triangles: RNA I promoter transcripts. Data are from J. Lemke and R. Gourse, unpublished.