title: Isolation and characterization of functional Shiga toxin subunits and renatured holotoxin.
abstract: Shiga toxin is a protein toxin produced by Shigella dysenteriae type I strains. In this report we present a procedure for the separation of functionally intact toxin A and B chains and for their reconstitution to form biologically active molecules. In agreement with the findings of others, the isolated A chain was shown to be a potent in vitro inhibitor of eukaryotic protein synthesis. The isolated B chain bound to HeLa cells and competitively inhibited the binding and cytotoxic activity of holotoxin. These findings show that the functional role of the B chain is to recognize cell surface functional receptors. By labelling the B subunit alone, prior to renaturation of holotoxin, the polypeptide chains were shown to associate noncovalently with a stoichiometry of one A chain and five B chains.
authors.affiliation: Department of Medicine, New England Medical Center, Boston, Massachusetts.
authors.forename: A
authors.initials: A
authors.lastname: Donohue-Rolfe
authors.forename: M
authors.initials: M
authors.lastname: Jacewicz
authors.forename: G T
authors.initials: GT
authors.lastname: Keusch
mesh_terms: D001427:Bacterial Toxins / Q000302:isolation & purification* / Q000633:toxicity; D001667:Binding, Competitive; D003432:Cross-Linking Reagents; D003603:Cytotoxins / Q000302:isolation & purification; D006367:HeLa Cells; D006801:Humans; D007096:Imidoesters; D010446:Peptide Fragments / Q000302:isolation & purification / Q000633:toxicity; D014176:Protein Biosynthesis / Q000187:drug effects; D011487:Protein Conformation; D022603:Shiga Toxins; D012762:Shigella dysenteriae / Q000032:analysis*
chemical_list: D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D003603:Cytotoxins; D007096:Imidoesters; D010446:Peptide Fragments; D022603:Shiga Toxins; C029326:dimethyl pimelimidate