Fig 5. CsfB inhibits in vitro transcription by RNA polymerase associated with σ^G or σ^E.

A: schematic representation of the promoter-containing PCR fragments used as templates for the in vitro transcription reactions. The expected size (in nucleotides) for each of the run-off products is indicated. B: effect of CsfB on in vitro transcription reactions with the indicated RNA polymerase holoenzymes. CsfB (130 nM) was either added to the reaction after mixing core (E; 13 nM) and the sigma subunit (“a”; 130 nM) or together with the sigma subunit to a mixture already containing core (“b”). The symbol “-”refers to a control reaction lacking CsfB. C and D: effect of the CsfB concentration, shown in molar ratio relative to RNA polymerase (13 nM), on in vitro transcription reactions with the indicated holoenzymes. CsfB was added at the same molar concentration as sigma (130 nM, 1x) or 2, 3, 4 and 8-fold excess and the mixture added to core RNA polymerase (13 nM). In B-D, arrows indicate the position of the expected run-off products, identified with arrows, which maintain the color code for the templates as represented in A. The position of molecular weight markers (in nucleotides) is shown on the left side of the panels.