FIGURE 4.
Steric clash with σ region 4.2 is responsible for δ-mediated transcriptional inhibition. A, SDS-PAGE of σA and σAΔ4.2. M represents molecular mass marker in kDa. B, in vitro transcription assay: 400 nm RNAP holo (prepared by incubating 400 nm RNAP core and 3 μm σAΔ4.2), 100 nm spo0B promoter DNA were used in the absence and presence of δ. Run-off transcript size is 57 nucleotides. Each experiment was repeated three times and the mean of relative amount of transcript at each concentration of δ with respect to the amount in the absence of δ were plotted as a bar graph (shown below of each panel). C, same as in B, but for the spo0B mut1 promoter DNA. Run-off transcript size is 57 nucleotides. D, EMSA: as in Fig. 3A but with RNAP-σAΔ4.2 holo.