title: RNA polymerase mutants that destabilize RNA polymerase-promoter complexes alter NTP-sensing by rrn P1 promoters.
abstract: Mutations in Escherichia coli rpoB or rpoC, selected for the ability to confer prototrophy on relA spoT strains, were found to affect transcription from rrn P1 promoters. Two mutant strains (beta RH454 and beta' delta 215-220) reduced transcription of rrn P1 core promoter-lacZ fusions but not of control promoter-lacZ fusions. Purified mutant RNAPs formed complexes with rrn P1 promoters that were much less stable than those formed by wild-type RNAP and required high concentrations of the initiating NTP for efficient rrn P1 transcription. The instability of the rrn P1 core promoter complexes with the mutant RNAPs and their altered regulatory properties support a recently proposed model for the control of rRNA transcription by changing concentrations of the initiating NTPs. We further suggest that destabilization of promoter complexes by the mutant RNAPs mimics effects of ppGpp, decreasing or increasing transcription depending on the kinetic properties of the specific promoter.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison 53706, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Bartlett
authors.forename: T
authors.initials: T
authors.lastname: Gaal
authors.forename: W
authors.initials: W
authors.lastname: Ross
authors.forename: R L
authors.initials: RL
authors.lastname: Gourse
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D002455:Cell Division; D002874:Chromosome Mapping; D018983:DNA Footprinting; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004795:Enzyme Stability / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D005798:Genes, Bacterial; D006160:Guanosine Triphosphate / Q000378:metabolism; D046911:Macromolecular Substances; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D012335:RNA, Ribosomal / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D046911:Macromolecular Substances; D012335:RNA, Ribosomal; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D012321:DNA-Directed RNA Polymerases