Sighting of unusual glycans

Here we will present three examples dealing with the first description of unconventional glycan structures synthesized by totally or partially different biosynthetic pathways. Primarily, it will be presented the N-glycans characterization of Paramecium Bursaria Chlorella Virus 1 (PBCV-1) major capsid protein (MCP) Vp54. Chloroviruses have a long evolutionary history, probably forgoing the eukaryotes development, thus it has been hypothesized that they could own a different glycosylation machinery. The structures of the four N-linked glycans attached to PBCV-1 MCP consist of a set of oligosaccharides not previously found in all the three domains of life. Very interestingly, these glycan structures are not located in a typical N-X-(T/S) consensus site [1-3]. A second example will regard the characterization of the lipopolysaccharide synthetized by the photosynthetic Bradyrhizobium strain, symbiont of Aeschynomene legumes. This bacterium synthesizes a unique LPS bearing a hopanoid covalently attached to lipid A. This was the first type that a covalent linkage between a lipid A and a Hopanoid unit was demonstrated [4]. Finally, it will be described the unique case of a patient with multiple genetic mutations that, perhaps interacting, lead to generation of hypersialylated N-glycans structures, never reported before in human serum.