Structural characterization of the N-linked pentasaccharide decorating glycoproteins of the halophilic archaeon Haloferax volcanii

Lina Kandiba, Chia Wei Lin, Markus Aebi, Jerry Eichler, Yann Guerardel

Research output: Contribution to journalArticlepeer-review

Abstract

N-Glycosylation is a post-translational modification performed in all three domains of life. In the halophilic archaea Haloferax volcanii, glycoproteins such as the S-layer glycoprotein are modified by an N-linked pentasaccharide assembled by a series of Agl (archaeal glycosylation) proteins. In the present study, mass spectrometry (MS) and nuclear magnetic resonance spectroscopy were used to define the structure of this glycan attached to at least four of the seven putative S-layer glycoprotein N-glycosylation sites, namely Asn-13, Asn-83, Asn-274 and Asn-279. Such approaches detected a trisaccharide corresponding to glucuronic acid (GlcA)-β1,4-GlcA-β1,4-glucose-β1-Asn, a tetrasaccharide corresponding to methyl-O-4-GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose- β1-Asn, and a pentasaccharide corresponding to hexose-1,2-[methyl-O-4-]GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose-β1-Asn, with previous MS and radiolabeling experiments showing the hexose at the non-reducing end of the pentasaccharide to be mannose. The present analysis thus corrects the earlier assignment of the penultimate sugar as a methyl ester of a hexuronic acid, instead revealing this sugar to be a methylated GlcA. The assignments made here are in good agreement with what was already known of the Hfx. volcanii N-glycosylation pathway from previous genetic and biochemical efforts while providing new insight into the process.

Original languageAmerican English
Pages (from-to)745-756
Number of pages12
JournalGlycobiology
Volume26
Issue number7
DOIs
StatePublished - 1 Jul 2016

Keywords

  • Archaea
  • Mass spectrometry
  • N-linked glycosylation
  • Nuclear magnetic resonance
  • S-layer glycoprotein

All Science Journal Classification (ASJC) codes

  • General Medicine

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