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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 Glc3Man9GlcNAc2-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.
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Contributor : Arnaud Lehner Connect in order to contact the contributor
Submitted on : Tuesday, July 24, 2018 - 3:05:33 PM
Last modification on : Friday, March 25, 2022 - 5:02:02 PM

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Bérengère Baïet, Carole Burel, Bruno Saint-Jean, Romain R. Louvet, Laurence Menu-Bouaouiche, et al.. N -Glycans of Phaeodactylum tricornutum Diatom and Functional Characterization of Its N -Acetylglucosaminyltransferase I Enzyme. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2011, 286 (8), pp.6152 - 6164. ⟨10.1074/jbc.M110.175711⟩. ⟨hal-01848363⟩



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