Fucosylated glycoproteins and fucosylated glycolipids play opposing roles in cholera intoxication
Cholera toxin (CT) is the etiological agent of cholera. Here we report that multiple classes of fucosylated glycoconjugates function in CT binding and intoxication of intestinal epithelial cells. In Colo205 cells, knockout of B3GNT5, the enzyme required for synthesis of lacto- and neolacto-series glycosphingolipids (GSLs), reduces CT binding but sensitizes cells to intoxication. Overexpressing B3GNT5 to generate more fucosylated GSLs confers protection against intoxication, indicating that fucosylated GSLs act as decoy receptors for CT. Knockout (KO) of B3GALT5 causes increased production of fucosylated O-linked and N-linked glycoproteins, and leads to increased CT binding and intoxication. Knockout of B3GNT5 in B3GALT5 KO cells eliminates production of fucosylated GSLs but increases intoxication, identifying fucosylated glycoproteins as functional receptors for CT. These findings provide insight into molecular determinants regulating CT sensitivity of host cells. Overall design: Colo205 cells infected with lentivirus encoding the Brunello genome-wide CRISPR KO pooled library (Addgene catalog no. 73178) were incubated with biotinylated cholera toxin B subunit and streptavidin-DTAF.  Cells with the highest 1% fluorescence and lowest 1% fluorescence were collected by fluorescence-activated cell sorting. sgRNA enrichment was determined relative to the input cell population.