title: N-glycans of Phaeodactylum tricornutum diatom and functional characterization of its N-acetylglucosaminyltransferase I enzyme.
abstract: N-glycosylation, a major co- and post-translational event in the synthesis of proteins in eukaryotes, is unknown in aquatic photosynthetic microalgae. In this paper, we describe the N-glycosylation pathway in the diatom Phaeodactylum tricornutum. Bio-informatic analysis of its genome revealed the presence of a complete set of sequences potentially encoding for proteins involved in the synthesis of the lipid-linked Glc(3)Man(9)GlcNAc(2)-PP-dolichol N-glycan, some subunits of the oligosaccharyltransferase complex, as well as endoplasmic reticulum glucosidases and chaperones required for protein quality control and, finally, the α-mannosidase I involved in the trimming of the N-glycan precursor into Man-5 N-glycan. Moreover, one N-acetylglucosaminyltransferase I, a Golgi glycosyltransferase that initiates the synthesis of complex type N-glycans, was predicted in the P. tricornutum genome. We demonstrated that this gene encodes for an active N-acetylglucosaminyltransferase I, which is able to restore complex type N-glycans maturation in the Chinese hamster ovary Lec1 mutant, defective in its endogeneous N-acetylglucosaminyltransferase I. Consistent with these data, the structural analyses of N-linked glycans demonstrated that P. tricornutum proteins carry mainly high mannose type N-glycans ranging from Man-5 to Man-9. Although representing a minor glycan population, paucimannose N-glycans were also detected, suggesting the occurrence of an N-acetylglucosaminyltransferase I-dependent maturation of N-glycans in this diatom.
authors.affiliation: Université de Rouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, Faculté des Sciences, 76821 Mont-Saint-Aignan Cédex, France.
authors.forename: Bérengère
authors.initials: B
authors.lastname: Baïet
authors.forename: Carole
authors.initials: C
authors.lastname: Burel
authors.forename: Bruno
authors.initials: B
authors.lastname: Saint-Jean
authors.forename: Romain
authors.initials: R
authors.lastname: Louvet
authors.forename: Laurence
authors.initials: L
authors.lastname: Menu-Bouaouiche
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Kiefer-Meyer
authors.forename: Elodie
authors.initials: E
authors.lastname: Mathieu-Rivet
authors.forename: Thomas
authors.initials: T
authors.lastname: Lefebvre
authors.forename: Hélène
authors.initials: H
authors.lastname: Castel
authors.forename: Aude
authors.initials: A
authors.lastname: Carlier
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Cadoret
authors.forename: Patrice
authors.initials: P
authors.lastname: Lerouge
authors.forename: Muriel
authors.initials: M
authors.lastname: Bardor
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D019295:Computational Biology / Q000379:methods; D006224:Cricetinae; D003412:Cricetulus; D017377:Diatoms / Q000201:enzymology* / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000235:genetics; D005816:Genetic Complementation Test / Q000379:methods; D055106:Genome-Wide Association Study / Q000379:methods; D006056:Golgi Apparatus / Q000201:enzymology / Q000235:genetics; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism
chemical_list: C117618:ADGRL2 protein, human; D011134:Polysaccharides; D043562:Receptors, G-Protein-Coupled; D017351:N-Acetylglucosaminyltransferases; C024850:alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase I