Isomeric Separation and Recognition of Anionic and Zwitterionic N-glycans from Royal Jelly Glycoproteins

Alba Hykollari,Daniel Malzl,Barbara Eckmair,Jorick Vanbeselaere,Patrick Scheidl,Chunsheng Jin,Niclas G Karlsson,Iain B.H Wilson,Katharina Paschinger

doi:10.1074/mcp.ra117.000462

Abstract

Royal jelly has received attention because of its necessity for the development of queen honeybees as well as claims of benefits on human health; this product of the hypopharyngeal glands of worker bees contains a large number of proteins, some of which have been claimed to have various biological effects only in their glycosylated state. However, although there have been glycomic and glycoproteomic analyses in the past, none of the glycan structures previously defined would appear to have potential to trigger specific biological functions. In the current study, whole royal jelly as well as single protein bands were subject to off-line LC-MALDI-TOF MS glycomic analyses, complemented by permethylation, Western blotting and arraying data. Similarly to recent in-depth studies on other insect species, previously overlooked glucuronic acid termini, sulfation of mannose residues and core β-mannosylation of the N-glycans were found; additionally, a relatively rare zwitterionic modification with phosphoethanolamine is present, in contrast to the phosphorylcholine occurring in lepidopteran species. Indicative of tissue-specific remodelling of glycans in the Golgi apparatus of hypopharyngeal gland cells, only a low amount of fucosylated or paucimannosidic glycans were detected as compared with other insect samples or even bee venom. The unusual modifications of hybrid and multiantennary structures defined here may not only have a physiological role in honeybee development, but represent epitopes recognized by pentraxins with roles in animal innate immunity.

Highlights

Royal jelly is a product of the hypopharyngeal and mandibular glands of worker honeybees [1]; its natural role is as the food source for worker and drone larvae for the first 3 days but induces queen development when fed beyond that time and remains, thereafter, the food for a queen’s entire life
MALDI-TOF MS of the anionic pool suggested the presence of glycans potentially modified with sulfate or glucuronic acid, neither of which have been reported for royal jelly glycans, but of a type familiar from our recent data on dipteran and lepidopteran N-glycomes [18, 19]
There are singular studies on glycomes or glycoproteins isolated from the silkworm Bombyx mori [48, 49], the flour beetle Tribolium castaneum [50] and the locust Locusta migratoria [51], of which the latter was most noteworthy as aminoethylphosphonate was detected as an antennal modification

Summary

Introduction

Royal jelly is a product of the hypopharyngeal and mandibular glands of worker honeybees [1]; its natural role is as the food source for worker and drone larvae for the first 3 days but induces queen development when fed beyond that time and remains, thereafter, the food for a queen’s entire life.

Results

Conclusion