Porcine intestinal glycosphingolipids recognized by F6-fimbriated enterotoxigenic Escherichia coli

Abstract

One important virulence factor of enterotoxigenic Escherichia coli is their ability to adhere via fimbrial adhesins to specific receptors located on the intestinal mucosa. Here, the potential glycosphingolipid receptors of enterotoxigenic F6-fimbriated E. coli were examined by binding of purified F6 fimbriae, and F6-expressing bacteria, to glycosphingolipids on thin-layer chromatograms. When intestinal mucosal non-acid glycosphingolipids from single pigs were assayed for F6 binding capacity, a selective interaction with two glycosphingolipids was observed. The binding-active glycosphingolipids were isolated and characterized as lactotriaosylceramide (GlcNAcβ3Galβ4Glcβ1Cer) and lactotetraosylceramide (Galβ3GlcNAcβ3Galβ4Glcβ1Cer). Further binding assays using a panel of reference glycosphingolipids showed a specific interaction between the F6 fimbriae and a number of neolacto core chain (Galβ4GlcNAc) glycosphingolipids. In addition, an occasional binding of the F6 fimbriae to sulfatide, galactosylceramide, lactosylceramide with phytosphingosine and/or hydroxy fatty acids, isoglobotriaosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide was obtained. From the results we conclude that lactotriaosylceramide and lactotetraosylceramide are major porcine intestinal receptors for F6-fimbriated E. coli.

A Topographical Atlas of Shiga Toxin 2e Receptor Distribution in the Tissues of Weaned Piglets

“…The presence of an additional hydroxyl group in the lipid moiety of a GSL seems important for the pathogenesis of bacterial infections and in particular for intestinal colonization of pathogens, since ceramide hydroxylation of GSL receptor molecules might play a functional role in increasing toxin affinity towards GSL receptors as shown for binding of Stxs to Gb3Cer [45]. Furthermore, hydroxylation of the ceramide moiety may exert a reinforcing effect for host-pathogen interaction suggesting an advantage for certain pathogens as shown for F4- and F6-fimbriated enterotoxigenic E. coli in adhesion studies with porcine intestinal GSLs [46,47] and F1C-fimbriated uropathogenic E. coli [48]. …”

Animal EnterotoxigenicEscherichia coli

“…Studies on the F6 receptors suggested that intestinal brush border receptors, particularly sulfatide, are released in the mucus of post-neonatal pigs inhibiting fimbriae-mediated adhesion and colonization (141–143). Lactotetraosylceramide, which was recently detected as a carbohydrate receptor moiety, was suggested to be inactivated by fucosylation in older pigs (144). In contrast, the adhesion and colonization by F18-fimbriated ETEC isolates was proposed to be dependent on receptors that develop progressively with age during the first 3 weeks after birth (145).…”

“…In addition to the two entero-adhesive properties of FasG, a third type of F6 binding occurs between the major subunit FasA and piglet brush border hydroxylated ceramide monohexoside (165). More recently, F6 fimbriae were shown to bind to lactotriaosylceramide and lactotetraosylceramide isolated from the intestines of 6 weeks old pigs (144). Whether these receptors are already expressed in younger neonatal piglets, which are the targets for F6-fimbriated ETEC, was not determined.…”

Membrane assembly of Shiga toxin glycosphingolipid receptors and toxin refractiveness of MDCK II epithelial cells

“…GSLs are attachment sites for a huge number of bacteria and viruses as well as targets for bacterial toxins (22)(23)(24)(25)(26). Plasma membrane segregation into microdomains is well recognized as a functional requirement for binding of pathogens and toxins to gain entry into cells (27)(28)(29)(30)(31).…”