Figure 2.

Effect of variant σ added in excess in solution on pausing in vitro. (A) Open complex was formed with RNAP containing either wild-type σ⁷⁰ (lanes 1–6) or σ⁷⁰ L402F (lanes 7–12); after washing, excess σ⁷⁰ L402F (lanes 4–6) or wild-type σ⁷⁰ (lanes 10–12) was added, as described. Reactions were sampled at 1, 2, and 5 min for each set of three. (B) As for A, except that the supplement was σ^S. RT, readthrough; T, terminated; P, paused.