title: Changes in conserved region 2 of Escherichia coli sigma 70 affecting promoter recognition.
abstract: We describe a mutation in rpoD, the gene encoding the sigma 70 subunit of RNA polymerase, which alters the promoter specificity of the holoenzyme in vivo. The mutant sigma causes a substantial and specific increase in the activity of mutant ant and lac promoters with a T.A to C.G substitution at position -12, the first position of the -10 hexamer. The rpoD mutation is a single base-pair substitution causing a Gln----His change at position 437, which is in a domain of conserved region 2.4 that is predicted to form an alpha-helix. Gln437 would lie one turn of the alpha-helix away from Thr440, which was previously implicated in recognition of position -12. The rpoD-QH437 mutation described here lends further support to the model that region 2.4 of sigma is involved in recognition of the 5' end of the -10 hexamer. In addition, two rpoD mutations with non-specific effects on promoter recognition are described.
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, 90089-1340.
authors.forename: C
authors.initials: C
authors.lastname: Waldburger
authors.forename: T
authors.initials: T
authors.lastname: Gardella
authors.forename: R
authors.initials: R
authors.lastname: Wong
authors.forename: M M
authors.initials: MM
authors.lastname: Susskind
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000648:ultrastructure; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000648:ultrastructure; D012045:Regulatory Sequences, Nucleic Acid; D012808:Sigma Factor / Q000502:physiology*; D013379:Substrate Specificity; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases