title: The sigma 70 subunit of RNA polymerase mediates a promoter-proximal pause at the lac promoter.
abstract: The sigma(70) subunit of RNA polymerase plays an essential role in transcription initiation. In addition, sigma(70) has a critical regulatory role during transcription elongation at the bacteriophage lambda late promoter, lambda P(R'). At this promoter, sigma(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 sigma(70) also mediates a pause in early elongation at the lac promoter (plac). Like that at lambda P(R'), 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 sigma(70) and the remainder of the transcription elongation complex. Bioinformatic analysis suggests that promoter-proximal sigma(70)-dependent pauses may play a role in the regulation of many bacterial promoters.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Bryce E
authors.initials: BE
authors.lastname: Nickels
authors.forename: Jayanta
authors.initials: J
authors.lastname: Mukhopadhyay
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Garrity
authors.forename: Richard H
authors.initials: RH
authors.lastname: Ebright
authors.forename: Ann
authors.initials: A
authors.lastname: Hochschild
mesh_terms: D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology; D007763:Lac Operon; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021122:Protein Subunits / Q000502:physiology; D012808:Sigma Factor / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; D021122:Protein Subunits; D012808:Sigma Factor; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases