Giant Virus displays an unusual class of complex N-Glycans

An unusual N-linked glycosylation scheme has been identified in the major capsid protein of a giant virus belonging to the Phycodnaviridae family.

• The virus encodes the machinery to glycosylate its major capsid protein which contains 4 glycosylation sites via a process which is thought to occur in the ctytoplasm.
• The Asn-linkage of the glycans to the protein does not occur on a typical consensus site.
• The glycans are attached to the protein via a beta glucose linkage.
• The glycan structure is made up of nine neutral residues ; dimethylated rhamnose, a hyperbranched fucose unit, and two rhamnoses with opposite (D and L) configuration and L arabinose ; they are organized in a highly branched fashion.

  

  The authors conclude that the chlorovirus glycosylation pathway may have existed prior the development of the endoplasmic reticulum and Golgi pathway. From a biotechnological point of view these results open the route to the identifications of new glycosyltransferases which are involved in glycan formation and remodelling