title: A novel bacterial transcription cycle involving sigma 54.
abstract: sigma 54 is the promoter recognition subunit of the form of bacterial RNA polymerase that transcribes from promoters with enhancer elements. DNase footprinting experiments show that sigma 54 is attached selectively to the template strand, which must be single-stranded for transcription initiation. sigma 54 remains bound at the promoter after core polymerase begins elongation, in contrast to the well-established sigma 70-holoenzyme transcription cycle. Permanganate footprinting experiments show that the bound sigma 54 and the elongating core RNA polymerase downstream of it are each associated with a single-strand DNA region. Template commitment assays show that the promoter-bound sigma 54 must be reconfigured before reinitiation of transcription can occur. This unexpected pathway raises interesting possibilities for transcriptional regulation, especially with regard to control at the level of reinitiation.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Tintut
authors.forename: J T
authors.initials: JT
authors.lastname: Wang
authors.forename: J D
authors.initials: JD
authors.lastname: Gralla
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000187:drug effects; D004277:DNA, Single-Stranded / Q000187:drug effects; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D008957:Models, Genetic; D011196:Potassium Permanganate / Q000494:pharmacology; D011485:Protein Binding; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C497751:rpoN protein, E coli; D011196:Potassium Permanganate; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54