title: A mutant RNA polymerase that forms unusual open promoter complexes.
abstract: We describe a mutant Escherichia coli RNA polymerase (RNAP) that forms stable open promoter complexes even at -20 degrees C but with a shortened melted region that extends downstream to only position -7. In the presence of initiating transcription substrates, the mutant RNAP undergoes a temperature-dependent isomerization, resulting in a promoter complex that is indistinguishable from the wild-type RNAP-promoter complex, with the melted region extended downstream to position +4. We propose that the open complex formed by the mutant RNAP represents an intermediate on the normal promoter-opening pathway and that our results support earlier findings that initial promoter opening occurs in the upstream region of the -10 promoter consensus element and subsequently extends downstream to encompass the transcription start site.
authors.affiliation: Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
authors.forename: K
authors.initials: K
authors.lastname: Severinov
authors.forename: S A
authors.initials: SA
authors.lastname: Darst
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D017384:Sequence Deletion; D013696:Temperature; D013816:Thermodynamics; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D046911:Macromolecular Substances; D012321:DNA-Directed RNA Polymerases