Rabbit sucrase-isomaltase contains a functional intestinal receptor for Clostridium difficile toxin A.
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.
Pothoulakis
C
C
Section of Gastroenterology, Boston University School of Medicine, Massachusetts, USA.
Gilbert
R J
RJ
Cladaras
C
C
Castagliuolo
I
I
Semenza
G
G
Hitti
Y
Y
Montcrief
J S
JS
Linevsky
J
J
Kelly
C P
CP
Nikulasson
S
S
Desai
H P
HP
Wilkins
T D
TD
LaMont
J T
JT
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
D001427:Bacterial Toxins; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile; D013394:Sucrase-Isomaltase Complex