title: Purification and characterization of the diphtheria toxin repressor.
abstract: The diphtheria toxin repressor gene (dtxR) encodes a protein (DtxR) that regulates transcription of the diphtheria toxin gene (tox) by an iron-dependent mechanism. Cloned dtxR was expressed in Escherichia coli from the phage T7 gene 10 promoter, and DtxR was purified. Specific binding of DtxR to the tox+ operator was dependent on reduction of DtxR and the presence of ferrous ions. DtxR protected a sequence of approximately 30 nucleotide pairs, partially overlapping the tox promoter and containing a region of dyad symmetry, from digestion by DNase I. DtxR exhibited very little binding to the mutant tox-201 operator region and failed to bind to the promoter/operator region of the ferric uptake regulation (fur) gene of E. coli.
authors.affiliation: Department of Microbiology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4977.
authors.forename: M P
authors.initials: MP
authors.lastname: Schmitt
authors.forename: E M
authors.initials: EM
authors.lastname: Twiddy
authors.forename: R K
authors.initials: RK
authors.lastname: Holmes
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001483:Base Sequence; D002848:Chromatography, DEAE-Cellulose; D003001:Cloning, Molecular; D003353:Corynebacterium diphtheriae / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004167:Diphtheria Toxin / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D009876:Operon; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004167:Diphtheria Toxin; C075586:DtxR protein, Corynebacterium diphtheriae; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins