title: Binding of Clostridium botulinum C2 toxin to asparagine-linked complex and hybrid carbohydrates.
abstract: Clostridium botulinum C2 toxin is a binary toxin composed of an enzymatic subunit (C2I) capable of ADP-ribosylating actin and a binding subunit (C2II) that is responsible for interaction with receptors on eukaryotic cells. Here we show that binding of C2 toxin depends on the presence of asparagine-linked carbohydrates. A recently identified Chinese hamster ovary cell mutant (Fritz, G., Schroeder, P., and Aktories, K. (1995) Infect. Immun. 63, 2334-2340) was found to be deficient in N-acetylglucosaminyltransferase I. C2 sensitivity of this mutant was restored by transfection of an N-acetylglucosaminyltransferase I cDNA. C2 toxin sensitivity was reduced after inhibition of alpha-mannosidase II. In contrast, Chinese hamster ovary cell mutants deficient in sialylated (Lec2) or galactosylated (Lec8) glycoconjugates showed an increase in toxin sensitivity compared with wild-type cells. Our results show that the GlcNAc residue linked beta-1,2 to the alpha-1,3-mannose of the asparagine-linked core structure is essential for C2II binding to Chinese hamster ovary cells.
authors.affiliation: Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 5, D-79104 Freiburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Eckhardt
authors.forename: H
authors.initials: H
authors.lastname: Barth
authors.forename: D
authors.initials: D
authors.lastname: Blöcker
authors.forename: K
authors.initials: K
authors.lastname: Aktories
mesh_terms: D000818:Animals; D001215:Asparaginase / Q000378:metabolism*; D001483:Base Sequence; D001905:Botulinum Toxins / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D017931:DNA Primers; D008361:Mannosidases / Q000037:antagonists & inhibitors; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D043323:alpha-Mannosidase
chemical_list: D017931:DNA Primers; D011134:Polysaccharides; D011994:Recombinant Proteins; D017351:N-Acetylglucosaminyltransferases; C024850:alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase I; D008361:Mannosidases; D043323:alpha-Mannosidase; D001905:Botulinum Toxins; D001215:Asparaginase; C096324:botulinum toxin type C