N-Glycan on the Non-Consensus N-X-C Glycosylation Site Impacts Activity, Stability, and Localization of the Sda Synthase B4GALNT2

Autor: Virginie Cogez, Dorothée Vicogne, Céline Schulz, Lucie Portier, Giulia Venturi, Jérôme de Ruyck, Mathieu Decloquement, Marc F. Lensink, Guillaume Brysbaert, Fabio Dall’Olio, Sophie Groux-Degroote, Anne Harduin-Lepers
Přispěvatelé: Cogez, Virginie, Vicogne, Dorothée, Schulz, Céline, Portier, Lucie, Venturi, Giulia, de Ruyck, Jérôme, Decloquement, Mathieu, Lensink, Marc F, Brysbaert, Guillaume, Dall'Olio, Fabio, Groux-Degroote, Sophie, Harduin-Lepers, Anne, Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 (UGSF), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576 (UGSF), University of Bologna/Università di Bologna, ANR-10-BLAN-1204,GALFISH,Régulation moléculaire et cellulaire de la beta1,4-GalNAcT-II dans les états physiologiques et pathologiques (cancers gastrointestinaux)(2010), Université de Lille, CNRS, Unité de Glycobiologie Structurale et Fonctionnelle (UGSF) - UMR 8576, Unité de Glycobiologie Structurale et Fonctionnelle - UMR 8576 [UGSF]
Rok vydání: 2023
Předmět:
Zdroj: International Journal of Molecular Sciences
Volume 24
Issue 4
Pages: 4139
International Journal of Molecular Sciences, 2023, International Journal of Molecular Sciences, 24 (4), pp.4139. ⟨10.3390/ijms24044139⟩
ISSN: 1422-0067
1661-6596
Popis: International audience; The Sda carbohydrate epitope and its biosynthetic B4GALNT2 enzyme are expressed in the healthy colon and down-regulated to variable extents in colon cancer. The human B4GALNT2 gene drives the expression of a long and a short protein isoform (LF-B4GALNT2 and SF-B4GALNT2) sharing identical transmembrane and luminal domains. Both isoforms are trans-Golgi proteins and the LF-B4GALNT2 also localizes to post-Golgi vesicles thanks to its extended cytoplasmic tail. Control mechanisms underpinning Sda and B4GALNT2 expression in the gastrointestinal tract are complex and not fully understood. This study reveals the existence of two unusual N-glycosylation sites in B4GALNT2 luminal domain. The first atypical N-X-C site is evolutionarily conserved and occupied by a complex-type N-glycan. We explored the influence of this N-glycan using site-directed mutagenesis and showed that each mutant had a slightly decreased expression level, impaired stability, and reduced enzyme activity. Furthermore, we observed that the mutant SF-B4GALNT2 was partially mislocalized in the endoplasmic reticulum, whereas the mutant LF-B4GALNT2 was still localized in the Golgi and post-Golgi vesicles. Lastly, we showed that the formation of homodimers was drastically impaired in the two mutated isoforms. An AlphaFold2 model of the LF-B4GALNT2 dimer with an N-glycan on each monomer corroborated these findings and suggested that N-glycosylation of each B4GALNT2 isoform controlled their biological activity.
Databáze: OpenAIRE
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