title: Transcription initiation-defective forms of sigma(54) that differ in ability To function with a heteroduplex DNA template.
abstract: Transcription by sigma(54)-RNA polymerase holoenzyme requires an activator that catalyzes isomerization of the closed promoter complex to an open complex. We examined mutant forms of Salmonella enterica serovar Typhimurium sigma(54) that were defective in transcription initiation but retained core RNA polymerase- and promoter-binding activities. Four of the mutant proteins allowed activator-independent transcription from a heteroduplex DNA template. One of these mutant proteins, L124P V148A, had substitutions in a sequence that had not been shown previously to participate in the prevention of activator-independent transcription. The remaining mutants did not allow efficient activator-independent transcription from the heteroduplex DNA template and had substitutions within a conserved 20-amino-acid segment (Leu-179 to Leu-199), suggesting a role for this sequence in transcription initiation.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Kelly
authors.forename: J A
authors.initials: JA
authors.lastname: Ferguson
authors.forename: T R
authors.initials: TR
authors.lastname: Hoover
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D009154:Mutation; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics*; D051877:RNA Polymerase Sigma 54; D012486:Salmonella typhimurium / Q000737:chemistry / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D009692:Nucleic Acid Heteroduplexes; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54