title: RNA polymerase and an activator form discrete subcomplexes in a transcription initiation complex.
abstract: Using high-resolution atomic force microscopy (AFM) we show that in a ternary complex of an activator protein, FIS, and RNA polymerase containing the sigma(70) specificity factor at the Escherichia coli tyrT promoter the polymerase and the activator form discrete, but connected, subcomplexes in close proximity. This is the first time that a ternary complex between an activator, a sigma(70) polymerase holoenzyme and promoter DNA has been visualised. Individually FIS and RNA polymerase wrap approximately 80 and 150 bp of promoter DNA, respectively. We suggest that the architecture of the ternary complex provides a general paradigm for the facilitation of direct, but weak, interactions between polymerase and an activator.
authors.affiliation: International University Bremen, Bremen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Maurer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fritz
authors.forename: Georgi
authors.initials: G
authors.lastname: Muskhelishvili
authors.forename: Andrew
authors.initials: A
authors.lastname: Travers
mesh_terms: D004247:DNA / Q000737:chemistry; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D035021:Factor For Inversion Stimulation Protein; D018625:Microscopy, Atomic Force; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000737:chemistry*
chemical_list: D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C501034:Fis protein, E coli; D014157:Transcription Factors; D004247:DNA; D012321:DNA-Directed RNA Polymerases