Abstract

Cholera and travellers' diarrhoea are caused by AB5 protein toxins that bind to ganglioside GM1 at the surface of the cells lining the intestine. Inhibition of this protein-carbohydrate interaction would prevent the toxin from entering the cells, and thus prevents toxin-induced diarrhoea. In this review we will describe the structures of the cholera and E. coli heat-labile toxins, and summarize the main strategies that have led to the development of monovalent and multivalent inhibitors of these toxins. A number of key design concepts emerge from these studies including the importance of pre-organization of the sugar residues within the monovalent ligands, and also the pre-organization of monovalent ligand groups within larger multivalent ligands. The importance of chelation and protein aggregation as mechanisms of multivalent inhibition is also discussed.