Identification of methylated GnTI-dependent N-glycans in Botryococcus brauni

Stefan Schulze, Eugen Urzica, Maarten J.M.F. Reijnders, Henri van de Geest, Sven Warris, Linda V. Bakker, Christian Fufezan, Vitor A.P. Martins dos Santos, Peter J. Schaap, Sander A. Peters, Michael Hippler*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

19 Citations (Scopus)


In contrast to mammals and vascular plants, microalgae show a high diversity in the N-glycan structures of complex N-glycoproteins. Although homologues for β1,2-N-acetylglucosaminyltransferase I (GnTI), a key enzyme in the formation of complex N-glycans, have been identified in several algal species, GnTI-dependent N-glycans have not been detected so far. We have performed an N-glycoproteomic analysis of the hydrocarbon oils accumulating green microalgae Botryococcus braunii. Thereby, the analysis of intact N-glycopeptides allowed the determination of N-glycan compositions. Furthermore, insights into the role of N-glycosylation in B. braunii were gained from functional annotation of the identified N-glycoproteins. In total, 517 unique N-glycosylated peptides have been identified, including intact N-glycopeptides that harbored N-acetylhexosamine (HexNAc) at the nonreducing end. Surprisingly, these GnTI-dependent N-glycans were also found to be modified with (di)methylated hexose. The identification of GnTI-dependent N-glycans in combination with N-glycan methylation in B. braunii revealed an uncommon type of N-glycan processing in this microalgae.
Original languageEnglish
Pages (from-to)1361-1369
JournalNew Phytologist
Issue number4
Publication statusPublished - 2017


  • Botryococcus braunii
  • gene ontology annotation
  • mass spectrometry
  • N-glycosylation
  • post-translational modification


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