The New Buzz about Sugars: Novel N‐Glycans in Bees, Moths and Mosquitoes

Abstract

Sugars cover the surfaces of all cells and a major class of these glycoconjugates are the asparagine‐linked oligosaccharides attached to glycoproteins (N‐glycans). The classical view has been that N‐glycans in ‘lower’ are simple. However, recent data shows that, other than plants, the diversity of N‐glycan modifications in non‐vertebrate species is extremely high. Based on isobaric/isomeric separation combined with chemical or enzymatic treatments and MALDI‐TOF MS/MS, our own studies on dipteran, lepidopteran and hymenopteran species (specifically mosquitoes, moths and the honeybee) reveal a variety of ‘charged’ modifications of N‐glycans from insects, such as glucuronic acid, sulphate, phosphoethanolamine and phosphorylcholine. In addition, unusual core mannosylation, variable antennal length as well as up to three branches increase the range of possibilities. In the honeybee, we also have evidence for tissue‐specific N‐glycosylation patterns when comparing larvae, royal jelly and venom, while immunomodulatory or immunogenic epitopes are found on N‐glycans from insect cell lines used as baculovirus expression hosts. It is also clear that each analysed insect species has its own N‐glycosylation profile due to variations in relative abundance or absence of certain glycan structures. Complementary to the MS analyses, binding to antibodies, lectins and pentraxins can be tested with either natural N‐glycan pools in an array format or glycoproteins on blots; thereby, interactions with proteins of the human innate immune system can be demonstrated. Our data not only show that the concept of ‘simple’ organisms possessing only ‘simple’ glycans is not a true reflection of the actually complex biosynthetic glycosylation capacity of insects, but have repercussions for the use of insect cell lines for recombinant protein expression.Support or Funding InformationThis work was supported by the Austrian Science Fund (FWF) by grants to K.P., A.H. and I.B.H.W.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.