Figure 1.

Construction of stalled Q⁸²-modified or unmodified complexes

1. Schematic of the experimental method used to construct defined populations of Q⁸²-modified complexes. The template was obtained from pSS100 and contained the phage 82 late gene promoter, the intrinsic terminator t82, a C-rich region for optimal Rho binding to the RNA, and an EcoR1 site. Distances are indicated from the transcription start site.
2. Gel resolution of elongation complexes filtered past t82 using either the oligo anti-t82 or the antiterminator Q⁸², and stalled at a downstream site using the roadblock protein EcoR1-Gln111. After incubation with the indicated components, reaction mixtures were separated into magnetic bead-bound pellet (P) and supernatant (S) fractions. Numbers in parentheses indicate lengths of the RNA transcripts.