The σ70 subunit of RNA polymerase plays an essential role in transcription initiation. In addition, σ70 has a critical regulatory role during transcription elongation at the bacteriophage λ late promoter, σPR′. At this promoter, σ 70 mediates a pause in early elongation through contact with a DNA sequence element in the initially transcribed region that resembles a promoter -10 element. Here we provide evidence that σ70 also mediates a pause in early elongation at the lac promoter (plac). Like that at λPR′, the pause at plac is facilitated by a sequence element in the initially transcribed region that resembles a promoter -10 element. Using biophysical analysis, we demonstrate that the pause-inducing sequence element at plac stabilizes the interaction between σ 70 and the remainder of the transcription elongation complex. Bioinformatic analysis suggests that promoter-proximal σ 70-dependent pauses may play a role in the regulation of many bacterial promoters.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology