FIGURE 4.

Rho promotes deaD mRNA transcription termination in vitro. (A) E. coli RNA polymerase and different amounts of purified Rho protein, as indicated, were added to a DNA template containing the deaD promoter and 955 bp of DNA downstream from the transcription initiation site. The radiolabeled transcription products were resolved by denaturing gel electrophoresis. The full-length runoff product is indicated by an arrow, whereas prematurely terminated transcripts are indicated by asterisks. Radiolabeled DNA molecular weight markers, run alongside the samples, are shown on the left, along with their sizes in nucleotides. (B) Transcription reactions were performed as in (A), except that a rho template was used. (C) Quantitation of transcription termination efficiency using deaD and rho templates. The relative amounts of full-length mRNA synthesis observed is plotted as a function of Rho concentration. Each data point represents an average from three to four replicates.