Lectin-glycan interaction

Because they are easily accessible, glycans displayed on the surface of mammalian cells provide enormous opportunities to bind to many microbial pathogens, ranging from viruses to molecular toxins and from pathogenic bacteria to parasites. In multivalent binding, multiple interactions between ligands and various receptors are common (Fig. 16.1). One representative example is ricin—a versatile and durable A-B-type toxin—in which one of the protein chains (the B chain) is a lectin that interacts and binds terminal galactose (Gal) on the surface of eukaryotic cells with multivalent interactions to facilitate entry of the other peptide chain (the A chain) into the cell to cause cellular death via the catalytic... 

Analytical tools have been developed in order to identify carbohydrate structures as well as carbohydrate-binding proteins and to understand their underlying structure-function relationships of protein-carbohydrate and carbohydrate-carbohydrate interactions lectin arrays [16], glycan microarrays [17, 18], glyco-nanoparticles [19], frontal affinity chromatography [20] and carbohydrate tools for metabolic labeling [21]. 

The traditional methods of evaluating the interactions of glycans and glycan-binding proteins are based on isothermal titration calorimetry, surface plasmon resonance (SPR), and enzyme-linked lectin assays. Recently, glycan arrays have been developed as a... 

Microbial pathogens utilize different types of lectins for targeting the glycans on the surface of host cells. Many bacteria are covered with pili or fimbriae that contain a very special class of lectins known as adhesins because they play a role in attachment to epithelial cells. These lectins are monomeric and comprise only one binding site. Because the adhesins are repeated on the pilus, a larger number of adhesins on the bacterial surface create multivalent interaction with the host glycans. 

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