GSBS Student Publications

Title

A mutant Escherichia coli sigma 70 subunit of RNA polymerase with altered promoter specificity

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology

Date

4-20-1989

Document Type

Article

Medical Subject Headings

Base Sequence; Chromosome Deletion; DNA-Directed RNA Polymerases; Escherichia coli; Genes, Bacterial; Lac Operon; Molecular Sequence Data; Mutation; *Promoter Regions (Genetics); Sigma Factor; Transcription Factors

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

A mutation is described that alters the promoter specificity of sigma 70, the primary sigma factor of Escherichia coli RNA polymerase. In strains carrying both the mutant and wild-type sigma gene (rpoD), the mutant sigma causes a large increase in the activity of mutant P22 ant promoters with A.T or C.G instead of the wild-type, consensus G.C base-pair at position -33, the third position of the consensus -35 hexamer 5'-TTGACA-3'. There is little or no effect on the activities of the wild-type and 23 other mutant ant promoters, including one with T.A at -33. The mutant sigma also activates E. coli lac promoters with A.T or C.G, but not T.A, at the corresponding position. The rpoD mutation (rpoD-RH588) changes a CGT codon to CAT. The corresponding change in sigma 70 is Arg588----His. This residue is in a region that is conserved among most sigma factors, a region that is also homologous with the helix-turn-helix motif of DNA-binding proteins. These results suggest that this region of sigma 70 is directly involved in recognition of the -35 hexamer.

Rights and Permissions

Citation: J Mol Biol. 1989 Apr 20;206(4):579-90.

Related Resources

Link to article in PubMed

Journal Title

Journal of molecular biology

PubMed ID

2661827