Oligomerization of the E. coli Core RNA Polymerase: Formation of (α2ββ'ω)2–DNA Complexes and Regulation of the Oligomerization by Auxiliary Subunits
Figure 4
Formation of putative tandem complexes by the DNA-bound E. coli RNA polymerase.
A. Transcriptional activity of the E. coli RNA polymerase with a synthetic hairpin-shaped DNA template incorporating an asymmetric dT-mismatch bubble (P). Note the production of a template-specific transcript (T) for Template A and little or no transcriptional activity with the control template (Template B) (both templates are shown schematically at the right). In vitro transcription was carried out in buffer D, as described in Materials and Methods. B. Formation of the (α2ββ'ω)2–Template A complexes. Reactions in lanes 2–3 and 5–6 were similar to those, respectively, in lanes 4–5 and 1–2 in Figure 2B, except that 32P 5′ end-labeled Template A DNA was used in this set, and the gel contained 0.05% DOC to visualize both single-copy RNA polymerase–DNA and (α2ββ'ω)2–DNA complexes. C. Similar to Figure 4B, but with a more gradual incremental increase in the core enzyme concentrations. Template C was similar to Template A, except that it contained a (dT)10 extension at the 5′ end. Quantitated results of the experiments are shown in the panel at the right. TA: Template A; TC: Template C.