Structure and biosynthesis of complex N‐glycan cores and antennae in nematodes

Abstract

There are thousands of nematode species, some of which are parasites such as Ascaris suum, Trichuris suis or Haemonchus contortus; others such as the popular model organism, Caenorhabditis elegans, are free‐living. Although all are animals, they lack some of the characteristics of glycosylation found in vertebrates, but their ‘foreign’ nature is relevant to the interactions of nematode parasites with their hosts. The presence of complex modifications of the chitobiose core region of nematode N‐glycans and of phosphorylcholine on the glycan antennae are typical, but the details are species‐specific. Whereas Caenorhabditis N‐glycans can contain up to four fucose residues, this number is reduced in parasitic species. Also galactosylation, at unusual positions, is a recurrent theme. Of the three core fucosyltransferases and one fucose‐modifying galactosyltransferase known, unusual and unexpected enzyme specificities have been revealed by studying both enzyme specificities and the effect on the glycome of deleting the relevant genes; even the processing hexosaminidases of nematodes are only distantly related to their ‘cousins’ in other invertebrates which are responsible for formation of paucimannosidic glycans. Thereby, glycomics, genetics and biochemistry are not only important tools for understanding nematode glycan biosynthesis, but open the way to identifying carbohydrate motifs which play roles in the interactions of these organisms with their hosts.Support or Funding InformationAustrian Science Fund (FWF) grants P21946 to K.P. and P23922 to I.W.