CHARACTERIZATION OF PORCINE INTESTINAL RECEPTORS FOR THE K88AC FIMBRIAL ADHESIN OF ESCHERICHIA-COLI AS MUCIN-TYPE SIALOGLYCOPROTEINS

We have previously identified two K88ac adhesin receptors (210 and 240 kDa),which are present in membrane preparations from adhesive but not nonadhesive porcine intestinal brush border cells; these adhesin rece ptors are postulated to be important determinants of the susceptibilit y of pigs to K88ac(+) enterotoxigenic Escherichia coil infections (A. IZ. Erickson, J. A. Willgohs, S. Y. McFarland, D. A. Benfield, and D. F. Francis, Infect. immun. 60:983-988, 1992). We now describe a proced ure for the purification of these two receptors. Receptors were solubi lized from adhesive intestinal brush border vesicles using deoxycholat e and were purified by gel filtration chromatography on Sepharose CL-4 B and then by hydroxyapatite chromatography. Amino acid compositional analyses indicated that the two receptors have similar amino acid comp ositions. The most distinguishing characteristic of both receptors is a high percentage of threonine and proline residues, Neuraminidase tre atment caused the K88ac adhesin receptors to migrate with a slower mob ility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel s, indicating that these receptors are sialoglycoproteins. Results fro m lectin-binding studies indicated that the receptors contain O-linked oligosaccharides composed of galactosyl (beta-1,3)N-acetylgalactosami ne, alpha-linked fucose, galactosyl(beta-1,4)N-acetylglucosamine, sial ic acid, galactose, and N-acetylgalactosamine. Collectively, these cha racteristics indicate that the K88ac adhesin receptors are mucin-type sialoglycoproteins.