Identification and characterization of the carbohydrate ligands recognized by pertussis toxin via a glycan microarray and surface plasmon resonance.

Binding of pertussis toxin (PTx) was examined by a glycan microarray; 53 positive hits fell into four general groups. One group represents sialylated biantennary compounds with an N-glycan core terminating in α2−6-linked sialic acid. The second group consists of multiantennary compounds with a canonical N-glycan core, but lacking terminal sialic acids, which represents a departure from the previous understanding of PTx binding to N-glycans. The third group consists of Neu5Acα2−3(lactose or N-acetyllactosamine) forms that lack the branched mannose core found in N-glycans; thus, their presentation is more similar to that of O-linked glycans and glycolipids. The fourth group of compounds consists of Neu5Acα2−8Neu5Acα2−8Neu5Ac, which is seen in the c series gangliosides and some N-glycans. Quantitative analysis by surface plasmon resonance of the relative affinities of PTx for terminal Neu5Acα2−3 versus Neu5Acα2−6, as well as the affinities for the trisaccharide Neu5Acα2−8Neu5Acα2−8Neu5Ac versus disaccharide,...