Methylation--an uncommon modification of glycans

Abstract

A methyl (Me) group on a sugar residue is a rarely reported event. Until now, this type of modification has been found in the animal kingdom only in worms and molluscs, whereas it is more frequently present in some species of bacteria, fungi, algae and plants, but not in mammals. The monosaccharides involved as well as the positions of the Me groups on the sugar vary with species. Methylation appears to play a role in some recognition events, but details are still unknown. This review summarises the current knowledge on methylation of sugars in all types of organism.

Fig 1. Typical methylated glycan structure.

(A) O-polysaccharide repeating unit of Mesorhizobium loti (Zdorovenko et al., 2009); (B) Polysaccharide repeating unit from the red seaweed Apophloea lyallii (Watt et al., 2002); (C) Polysaccharide repeating unit isolated from fruiting bodies of Lagernaria siceraria (Ghosh et al., 2009); (D) N-glycan from Dugesia japonica (Paschinger et al., 2011); (E) and (F) N-glycans from Arion lusitanicus (Gutternigg et al., 2004).