N-Glycans of Phaeodactylum tricornutum Diatom and Functional Characterization of Its N-Acetylglucosaminyltransferase I Enzyme
|Author(s)||Baiet Berengere1, Burel Carole1, Saint-Jean Bruno2, Louvet Romain1, Menu-Bouaouiche Laurence1, Kiefer-Meyer Marie-Christine1, Mathieu-Rivet Elodie1, Lefebvre Thomas3, Castel Helene3, Carlier Aude2, Cadoret Jean-Paul2, Lerouge Patrice1, Bardor Muriel1|
|Affiliation(s)||1 : Univ Rouen, Lab Glycobiol & Matrice Extracellulaire Vegetale, Fac Sci, F-76821 Mont St Aignan, France.
2 : Ctr Nantes, Inst Francais Rech Exploitat Mer, Lab Physiol & Biotechnol Algues, F-44311 Nantes 03, France.
3 : Univ Rouen, INSERM, Lab Differenciat & Commun Neuronale & Neuroendocr, Fac Sci,U982,IFRM23, F-76821 Mont St Aignan, France.
|Source||Journal Of Biological Chemistry (0021-9258) (Amer Soc Biochemistry Molecular Biology Inc), 2011-02 , Vol. 286 , N. 8 , P. 6152-6164|
|WOS© Times Cited||47|
|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 alpha-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.|