Regulation of the SLT-1A toxin operon by a ferric uptake regulatory protein in toxinogenic strains of Shigella dysenteriae type 1.
The regulation of Shiga toxin expression in a clinical isolate of S. dysenteriae 1 by the Fe-Fur (Iron-ferric uptake regulatory protein) repressor complex was investigated. The presence of an endogenous Fur repressor protein capable of binding to either a Fur binding consensus sequence or the regulatory region of SLT-1A was determined in toxinogenic strains of S. dysenteriae. Plasmid constructs bearing Fur binding sites fused to readily assayable reporter genes were used. Plasmid pSC27.1 contains a 21 bp synthetic oligonucleotide Fur protein binding consensus sequence located upstream to the gene for beta-galactosidase. Plasmid pSC105 contains the regulatory sequences of Shiga-like toxin-1A located upstream to the gene for alkaline phosphatase. In an analogous fashion to Shiga toxin regulation in S. dysenteriae 1, transformants bearing either pSC27.1 or pSC105 plasmid DNA were repressed in gene product expression when grown in minimal medium supplemented with iron. Conversely, transformants were de-repressed when grown under iron limiting conditions. These data suggest the presence of Fe-Fur mediated regulation of toxinogenesis in clinical isolates of S. dysenteriae.
Svinarich
D M
DM
Department of Molecular Biology and Genetics, Wayne State University School of Medicine, Detroit, MI 48201.
Palchaudhuri
S
S
D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D003603:Cytotoxins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007501:Iron / Q000378:metabolism; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics*; D022622:Shiga Toxin 1; D022603:Shiga Toxins; D012762:Shigella dysenteriae / Q000235:genetics*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D012097:Repressor Proteins; D022622:Shiga Toxin 1; D022603:Shiga Toxins; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron