title: Multiple roles of the RNA polymerase beta subunit flap domain in sigma 54-dependent transcription.
abstract: Recent determinations of the structures of the bacterial RNA polymerase (RNAP) and promoter complex thereof establish that RNAP functions as a complex molecular machine that contains distinct structural modules that undergo major conformational changes during transcription. However, the contribution of the RNAP structural modules to transcription remains poorly understood. The bacterial core RNAP (alpha(2)beta beta'omega; E) associates with a sigma (sigma) subunit to form the holoenzyme (E sigma). A mutation removing the beta subunit flap domain renders the Escherichia coli sigma(70) RNAP holoenzyme unable to recognize promoters. sigma(54) is the major variant sigma subunit that utilizes enhancer-dependent promoters. Here, we determined the effects of beta flap removal on sigma(54)-dependent transcription. Our analysis shows that the role of the beta flap in sigma(54)-dependent and sigma(70)-dependent transcription is different. Removal of the beta flap does not prevent the recognition of sigma(54)-dependent promoters, but causes multiple defects in sigma(54)-dependent transcription. Most importantly, the beta flap appears to orchestrate the proper formation of the E sigma(54) regulatory center at the start site proximal promoter element where activator binds and DNA melting originates.
authors.affiliation: Department of Biological Sciences, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, Imperial College Road, London SW7 2AZ, United Kingdom.
authors.forename: Siva R
authors.initials: SR
authors.lastname: Wigneshweraraj
authors.forename: Konstantin
authors.initials: K
authors.lastname: Kuznedelov
authors.forename: Konstantin
authors.initials: K
authors.lastname: Severinov
authors.forename: Martin
authors.initials: M
authors.lastname: Buck
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D016172:DNA Fingerprinting; D015342:DNA Probes; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism; D014644:Genetic Variation; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D015342:DNA Probes; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C497751:rpoN protein, E coli; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; C105078:RNA polymerase beta subunit