title: Rabbit sucrase-isomaltase contains a functional intestinal receptor for Clostridium difficile toxin A.
abstract: The intestinal effects of Clostridium difficile toxin A are inidated by toxin binding to luminal enterocyte receptors. We reported previously that the rabbit ileal brush border (BB) receptor is a glycoprotein with an alpha-d-galactose containing trisaccharide in the toxin-binding domain (1991. J. Clin. Invest. 88:119-125). In this study we characterized the rabbit ileal BB receptor for this toxin. Purified toxin receptor peptides of 19 and 24 amino acids showed 100% homology with rabbit sucrase-isomaltase (SI). Guinea pig receptor antiserum reacted in Western blots with rabbit SI and with the purified toxin receptor. Antireceptor IgG blocked in vitro binding of toxin A to rabbit ileal villus cell BB. Furthermore, anti-SI IgG inhibited toxin A-induced secretion (by 78.1%, P < 0.01), intestinal permeability (by 80.8%, P < 0.01), and histologic injury (P < 0.01) in rabbit ileal loops in vivo. Chinese hamster ovary cells transfected with SI cDNA showed increased intracellular calcium increase in response to native toxin (holotoxin) or to a recombinant 873-amino acid peptide representing the receptor binding domain of toxin A. These data suggest that toxin A binds specifically to carbohydrate domains on rabbit ileal SI, and that such binding is relevant to signal transduction mechanisms that mediate in vitro and in vivo toxicity.
authors.affiliation: Section of Gastroenterology, Boston University School of Medicine, Massachusetts, USA.
authors.forename: C
authors.initials: C
authors.lastname: Pothoulakis
authors.forename: R J
authors.initials: RJ
authors.lastname: Gilbert
authors.forename: C
authors.initials: C
authors.lastname: Cladaras
authors.forename: I
authors.initials: I
authors.lastname: Castagliuolo
authors.forename: G
authors.initials: G
authors.lastname: Semenza
authors.forename: Y
authors.initials: Y
authors.lastname: Hitti
authors.forename: J S
authors.initials: JS
authors.lastname: Montcrief
authors.forename: J
authors.initials: J
authors.lastname: Linevsky
authors.forename: C P
authors.initials: CP
authors.lastname: Kelly
authors.forename: S
authors.initials: S
authors.lastname: Nikulasson
authors.forename: H P
authors.initials: HP
authors.lastname: Desai
authors.forename: T D
authors.initials: TD
authors.lastname: Wilkins
authors.forename: J T
authors.initials: JT
authors.lastname: LaMont
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins; D001665:Binding Sites; D016466:CHO Cells; D016360:Clostridioides difficile / Q000472:pathogenicity*; D006224:Cricetinae; D004768:Enterotoxins / Q000378:metabolism*; D006168:Guinea Pigs; D007421:Intestine, Small / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D011817:Rabbits; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism*; D014162:Transfection
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile; D013394:Sucrase-Isomaltase Complex