Site-specific glycoproteomic characterization of ES-62: The major secreted product of the parasitic worm Acanthocheilonema viteae.

Simon J North,James Doonan,Anne Dell,Felicity E Lumb,William Harnett,Kwamina Botchway,Stuart M Haslam

doi:10.1093/glycob/cwz035

Simon J North, James Doonan + Show 5 more

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https://doi.org/10.1093/glycob/cwz035

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Journal: Glycobiology	Publication Date: May 16, 2019
Citations: 13	License type: CC BY 4.0

Affiliation: Imperial College London, University of Strathclyde

Abstract

ES-62 is the major secreted product of the parasitic filarial nematode Acanthocheilonema viteae and has potent anti-inflammatory activities as a consequence of posttranslational decoration by phosphorylcholine (PC). Previously, we showed that ES-62’s PC was attached to N-linked glycans, and using fast atom bombardment mass spectrometry, we characterized the structure of the glycans. However, it was unknown at this time which of ES-62’s four potential N-glycosylation sites carries the PC-modified glycans. In the present study, we now employ more advanced analytical tools—nano-flow liquid chromatography with high-definition electrospray mass spectrometry—to show that PC-modified glycans are found at all four potential N-glycosylation sites. Also, our earlier studies showed that up to two PC groups were detected per glycan, and we are now able to characterize N-glycans with up to five PC groups. The number per glycan varies in three of the four glycosylation sites, and in addition, for the first time, we have detected PC on the N-glycan chitobiose core in addition to terminal GlcNAc. Nevertheless, the majority of PC is detected on terminal GlcNAc, enabling it to interact with the cells and molecules of the immune system. Such expression may explain the potent immunomodulatory effects of a molecule that is considered to have significant therapeutic potential in the treatment of certain human allergic and autoimmune conditions.

Highlights

ES-62 is the major secreted product of the parasitic rodent filarial nematode Acanthocheilonema viteae (Harnett et al 1989)
Samples of the purified ES-62 were subjected to a panel of enzymatic and chemical treatments, designed to characterize the occupancy and glycoforms present at each putative N-glycosylation site
Of particular relevance is its PC moiety as this appears to be essentially responsible for its anti-inflammatory activities and constitutes the starting point for an small molecule analogues (SMAs) drug discovery program (Al-Riyami et al 2013)

Summary

Introduction

ES-62 is the major secreted product of the parasitic rodent filarial nematode Acanthocheilonema viteae (Harnett et al 1989). As a consequence of this, ES-62 has been tested in a range of mouse models of allergic and autoimmune conditions and was found to offer protection against the development of lung and skin hypersensitivity (Melendez et al 2007), arthritis (McInnes et al 2003), systemic lupus erythematosus (SLE) (Rodgers et al 2015). Site-specific glycoproteomic characterization of ES-62 and the accelerated atherosclerosis associated with SLE (Aprahamian et al 2015). For this reason, ES-62 is considered to have significant therapeutic potential against such conditions and toward this, novel synthetic drug-like small molecule analogues (SMAs), which mirror the parent molecules capabilities, have been successfully produced (Al-Riyami et al 2013)

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