Establishing Rules for Self-Adhesion and Aggregation of -Glycan Sugars Using Virus Glycan Shields.

The surfaces of cells and pathogens are covered with short polymers of sugars known as glycans. Complex -glycans have a core of three mannose sugars with distal repeats of -acetylglucosamine and galactose sugars terminating with sialic acid (SA). Long-range tough and short-range brittle self-adhesions were observed between SA and mannose residues, respectively, in ill-defined artificial monolayers.

Complex-type N-glycans on VSV-G pseudotyped HIV exhibit 'tough' sialic and 'brittle' mannose self-adhesions.

The complex-type glycan shields of eukaryotic cells have a core layer of mannose residues buried under tiers of sugars that end with sialic acid (SA) residues. We investigate if the self-latching of mannose residues, earlier reported in pure monolayer studies, also manifests in the setting of a complex-type glycan shield. Would distal SA residues impede access to the mannose core? The interactions of mannobiose-, SA-, and lactose-coated probes with the complex-type VSV-G glycan shield on an HIV pseudovirus were studied with force-spectroscopy and gold-nanoparticle solutions.