The sigma 70 subunit of RNA polymerase induces lacUV5 promoter-proximal pausing of transcription.
The sigma(70) subunit of Escherichia coli RNA polymerase (RNAP) is a transcription initiation factor that can also be associated with RNAP during elongation. We provide biochemical evidence that sigma(70) induces a transcription pause at the lacUV5 promoter after RNAP has synthesized a 17-nucleotide transcript. The sigma(70)-dependent pausing requires an interaction between sigma(70) and a part of the lac repressor operator sequence resembling a promoter -10 consensus. The polysaccharide heparin triggers the release of sigma(70) from the paused complexes, supporting the view that during the transition from initiation to elongation the interactions between sigma(70) and core RNAP are weakened. We propose that the binding and retention of sigma(70) in elongation complexes are stabilized by its ability to form contacts with DNA of the transcription bubble. In addition, we suggest that the sigma(70) subunit in the elongation complex may provide a target for regulation of gene expression.
Brodolin
Konstantin
K
Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia. brodolin@img.ras.ru
Zenkin
Nikolay
N
Mustaev
Arkady
A
Mamaeva
Daria
D
Heumann
Hermann
H
D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology; D007763:Lac Operon; D009875:Operator Regions, Genetic; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021122:Protein Subunits; D012808:Sigma Factor / Q000502:physiology*; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; D021122:Protein Subunits; D012808:Sigma Factor; D004247:DNA; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases