title: Modification of the glycolipid-binding specificity of vero cytotoxin by polymyxin B and other cyclic amphipathic peptides.
abstract: Polymyxin B, an amphipathic cyclic decapeptide produced by Bacillus polymyxa, is routinely used in the extraction of the components from the periplasmic space of gram-negative bacteria. Vero cytotoxin 1 (VT1) is an Escherichia coli-elaborated subunit toxin which binds to the glycolipid globotriosylceramide (Gal-alpha 1-4-Gal beta 1-4-Glc-ceramide [Gb3]) and has been strongly implicated in the etiology of the hemolytic uremic syndrome and hemorrhagic colitis. We now show by in vitro glycolipid-binding assays that in the presence of low concentrations of polymyxin B, globotetraosylceramide (GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-ceramide [Gb4]) is also recognized by both the VT1 B (binding) subunit and holotoxin. Melittin, a 26-amino-acid cyclic peptide of similar amphipathic nature, produced the same effect, whereas a hydrophobic blocking agent did not. Triton X-100 did not increase binding of VT1 to Gb4 but prevented glycolipid binding in toto at concentrations above 0.5%. Caution is therefore advised in the analysis of VT1 glycolipid binding in the presence of amphipathic peptides.
authors.affiliation: Department of Microbiology, Hospital for Sick Children, Toronto, Ontario.
authors.forename: S
authors.initials: S
authors.lastname: Head
authors.forename: K
authors.initials: K
authors.lastname: Ramotar
authors.forename: C
authors.initials: C
authors.lastname: Lingwood
mesh_terms: D001427:Bacterial Toxins / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D005915:Globosides / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism*; D066298:In Vitro Techniques; D008555:Melitten / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D022622:Shiga Toxin 1; D014281:Trihexosylceramides
chemical_list: D001427:Bacterial Toxins; D005915:Globosides; D006028:Glycosphingolipids; D011113:Polymyxins; D011956:Receptors, Cell Surface; D022622:Shiga Toxin 1; D014281:Trihexosylceramides; C024032:globotetraosylceramide; D008555:Melitten; C018549:globotriaosylceramide; D011112:Polymyxin B