title: Nucleotide sequence of the Shiga-like toxin genes of Escherichia coli.
abstract: We have determined the nucleotide sequence of the sltA and sltB genes that encode the Shiga-like toxin (SLT) produced by Escherichia coli phage H19B. The amino acid composition of the A and B subunits of SLT is very similar to that previously established for Shiga toxin from Shigella dysenteriae 1, and the deduced amino acid sequence of the B subunit of SLT is identical with that reported for the B subunit of Shiga toxin. The genes for the A and B subunits of SLT apparently constitute an operon, with only 12 nucleotides separating the coding regions. There is a 21-base-pair region of dyad symmetry overlapping the proposed promoter of the slt operon that may be involved in regulation of SLT production by iron. The peptide sequence of the A subunit of SLT is homologous to the A subunit of the plant toxin ricin, providing evidence for the hypothesis that certain prokaryotic toxins may be evolutionarily related to eukaryotic enzymes.
authors.forename: S B
authors.initials: SB
authors.lastname: Calderwood
authors.forename: F
authors.initials: F
authors.lastname: Auclair
authors.forename: A
authors.initials: A
authors.lastname: Donohue-Rolfe
authors.forename: G T
authors.initials: GT
authors.lastname: Keusch
authors.forename: J J
authors.initials: JJ
authors.lastname: Mekalanos
mesh_terms: D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D012276:Ricin / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D022622:Shiga Toxin 1; D022603:Shiga Toxins; D012762:Shigella dysenteriae / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D022622:Shiga Toxin 1; D022603:Shiga Toxins; D012276:Ricin