N-Linked Glycans of Chloroviruses Sharing a Core Architecture without Precedent

N-glycosylation is afundamental modification of
proteins and exists in the three domains of life and in some
viruses,including the chloroviruses,for whichanew type of
core N-glycan is herein described. This N-glycan core struc-
ture,common to all chloroviruses,isapentasaccharide with
a b-glucose linked to an asparagine residue which is not located
in the typical sequon N-X-T/S.The glucose is linked to
aterminal xylose unit and ahyperbranched fucose,which is in
turn substituted with aterminal galactose and asecond xylose
residue.The thirdposition of the fucose unit is always linked to
arhamnose,which is asemiconserved element because its
absolute configuration is virus-dependent. Additional decora-
tions occur on this core N-glycan and represent amolecular
signature for each chlorovirus.