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Infect Immun, April 1998, p. 1613-1621, Vol. 66, No. 4
Department of Veterinary Science, South
Dakota State University, Brookings, South Dakota 57007-1396
Received 12 September 1997/Returned for modification 23 October
1997/Accepted 7 January 1998
We have previously identified two mucin-type sialoglycoproteins
from porcine intestinal epithelial cells with approximate molecular
masses of 210 (intestinal mucin-type glycoprotein IMTGP-1) and 240 kDa
(IMTGP-2) as receptors for the K88ab and K88ac fimbrial adhesins of
Escherichia coli. These receptors are detected in intestinal brush border membrane preparations from pigs with adhesive phenotypes but not from pigs with nonadhesive phenotypes and are postulated to be important determinants of the susceptibility of pigs
to K88ab+ and K88ac+ enterotoxigenic E. coli infections. Using exoglycosidase digestion studies, we have
now determined that
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Copyright © 1998, American Society for Microbiology. All rights reserved.
Characterization of the Carbohydrate Moiety of
Intestinal Mucin-Type Sialoglycoprotein Receptors for the
K88ac Fimbrial Adhesin of Escherichia coli
-linked galactose is an important component in
the recognition of IMTGP-1 and IMTGP-2 by the K88ac adhesin. In
addition, we observed a differential distribution of the K88ac adhesin
binding activity of IMTGP-1 and IMTGP-2 along the crypt-villus axis,
suggesting that receptor activity is dependent on the maturation state
of the intestinal epithelial cells. Brush borders from immature
intestinal epithelial cells possessed the highest concentrations of
IMTGP-1 and IMTGP-2 receptor activity, with a progressive decrease in
receptor activity as the cells mature. To characterize the differences
in the carbohydrate moieties of IMTGP-1 and IMTGP-2, we developed a
procedure for purifying the receptors, using phenol extraction followed
by serial lectin affinity chromatography. Carbohydrate compositional
analysis of the purified receptors indicated that the carbohydrate
moieties of IMTGP-1 and IMTGP-2 consist of both N- and O-glycans
containing galactose, glucose, sialic acid, mannose,
N-acetylgalactosamine, N-acetylglucosamine, and
fucose. The major difference between the two receptors is that IMTGP-2
contains a higher percentage of monosaccharides (mannose and glucose)
commonly found in N-glycans.
*
Corresponding author. Mailing address: Department of
Veterinary Science, P.O. Box 2175, South Dakota State University,
Brookings, SD 57007-1396. Phone: (605) 688-5171. Fax: (605) 688-6003. E-mail: ericksoa{at}mg.sdstate.edu.
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