Identification of an intestinal neutral glycosphingolipid as a phenotype-specific receptor for the K88ad fimbrial adhesin of Escherichia coli

In this study, we identified a receptor for the K88ad fimbrial adhesin of E scherichia coli in neutral glycosphingolipid preparations from intestinal e pithelial cells of K88ad-adhesive pigs, which was absent in preparations fr om K88ad-nonadhesive pigs. Neither K88ab nor K88ac adhesin variants bound t o this neutral glycosphingolipid. Because this receptor is an intestinal gl ycosphingolipid that binds K88ad adhesin, it has been designated IGLad. Car bohydrate compositional analysis of a partially purified preparation of IGL ad identified galactose, glucose, and N-acetylglucosamine in a ratio of 1.5 :1.0:0.5 as the major monosaccharides. Preliminary characterization experim ents using lectins showed that IGLad contains the terminal glycanic structu re Gal beta 1-4GlcNAc. Removal of terminal beta-linked galactose residues f rom IGLad decreased the recognition of IGLad by the K88ad adhesin, indicati ng that terminal beta-linked galactose is an essential component of the K88 ad adhesin recognition site on IGLad, Studies with purified glycosphingolip id standards demonstrated that K88ad adhesin binds to neolactotetraosylcera mide (nLc(4)Cer) (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer), lactotriosylceramide (GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer) and lacto tetraosylceramide (Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer). Based on these studies, IGLad appears to be nLc(4)Cer.