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Molecular basis for fibroblast growth factor 23 O-glycosylation by GalNAc-T3

DOI: 10.1038/s41589-019-0444-x DOI Help

Authors: Matilde De Las Rivas (University of Zaragoza) , Earnest James Paul Daniel (Case Western Reserve University) , Yoshiki Narimatsu (University of Copenhagen) , Ismael Compañón (Universidad de La Rioja) , Kentaro Kato (University of Copenhagen; Institute of Tropical Medicine Nagasaki University) , Pablo Hermosilla (Universidad de Zaragoza) , Aurélien Thureau (Synchrotron SOLEIL) , Laura Ceballos-laita (University of Zaragoza) , Helena Coelho (Universidade de Nova de Lisboa; CIC bioGUNE) , Pau Bernadó (CNRS, Université de Montpellier) , Filipa Marcelo (Universidade de Nova de Lisboa) , Lars Hansen (University of Copenhagen) , Ryota Maeda (Kyoto University) , Anabel Lostao (Universidad de Zaragoza) , Francisco Corzana (Universidad de La Rioja) , Henrik Clausen (University of Copenhagen) , Thomas A. Gerken (Case Western Reserve University) , Ramon Hurtado-guerrero (University of Zaragoza; University of Copenhagen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Chemical Biology , VOL 44

State: Published (Approved)
Published: January 2020
Diamond Proposal Number(s): 14739

Abstract: Polypeptide GalNAc-transferase T3 (GalNAc-T3) regulates fibroblast growth factor 23 (FGF23) by O-glycosylating Thr178 in a furin proprotein processing motif RHT178R↓S. FGF23 regulates phosphate homeostasis and deficiency in GALNT3 or FGF23 results in hyperphosphatemia and familial tumoral calcinosis. We explored the molecular mechanism for GalNAc-T3 glycosylation of FGF23 using engineered cell models and biophysical studies including kinetics, molecular dynamics and X-ray crystallography of GalNAc-T3 complexed to glycopeptide substrates. GalNAc-T3 uses a lectin domain mediated mechanism to glycosylate Thr178 requiring previous glycosylation at Thr171. Notably, Thr178 is a poor substrate site with limiting glycosylation due to substrate clashes leading to destabilization of the catalytic domain flexible loop. We suggest GalNAc-T3 specificity for FGF23 and its ability to control circulating levels of intact FGF23 is achieved by FGF23 being a poor substrate. GalNAc-T3’s structure further reveals the molecular bases for reported disease-causing mutations. Our findings provide an insight into how GalNAc-T isoenzymes achieve isoenzyme-specific nonredundant functions.

Journal Keywords: Carbohydrates; Enzymes; Mechanism of action; X-ray crystallography

Subject Areas: Biology and Bio-materials


Instruments: I24-Microfocus Macromolecular Crystallography