Structural basis of glycoprotein recognition by the human folding sensor UDP-glucose:glycoprotein glucosyltransferase
9 affiliations
- 1Structural Glycobiology Laboratory, Department of Structural and Molecular Biology, Institute of Molecular Biology of Barcelona, Spanish National Research Council, Barcelona Science Park, Barcelona, Catalonia 08028, Spain
- 2Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina
- 3Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA 01003
- 4Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA 01003
- 5Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
- 6Center for Cooperative Research in Biomaterials, Basque Research and Technology Alliance, Donostia-San Sebastián 20014, Spain
- 7Centro Nacional de Biotecnología, Spanish National Research Council, Madrid 28049, Spain
- 8Institute of Agricultural Biology and Biotechnology, National Research Council of Italy, Milano 20133, Italy
- 9Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003
Abstract
UDP-glucose:glycoprotein glucosyltransferase 1 (UGGT1) plays a central role in quality control of glycoprotein folding within the early secretory pathway, yet the molecular basis of UGGT1 substrate recognition remains poorly understood. Here, we report cryo-EM structures of human full-length multidomain UGGT1. Monomeric UGGT1 structures reveal two conformational states corresponding to “open” and “closed” architectures. Three-dimensional variability and molecular dynamics simulations suggest the existence of intermediate conformations, leading to a model in which a continuum of structural transitions underlies UGGT1 function. Notably, in the open state, the EM-maps reveal at the top of the U-shaped protein a density that bridges the sensory TRXL2 and the glucosyltransferase catalytic domains, consistent with substrate association. This observation supports a mode of binding that places the substrate near the catalytic domain. A dimeric form of UGGT1 was observed in which the glycoprotein substrate binding sites are occluded, suggesting that dimerization may regulate UGGT1 activity. To better understand the spatial relationship between the site of misfolding and that of UGGT-mediated N-glycan reglucosylation, we identified N-glycosylation sites on endogenous glycoprotein substrates by glycoproteomics. No consensus sequence was found flanking modified sites, indicating that substrate recognition relies on mechanisms beyond primary sequence. Mutations in the UGGT1 gene cause a novel congenital disorder of glycosylation characterized by developmental delay and intellectual disability, and the human UGGT1 structure helps explain how disease-associated missense and deletion variants disrupt function. Together, our data provide insight into the relationship between UGGT1 structure and function, integrating enzyme conformational states with client glycoprotein interaction and processing.
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BibTeX
@article{aparicio2026structural,
title = {{Structural basis of glycoprotein recognition by the human folding sensor UDP-glucose:glycoprotein glucosyltransferase}},
author = {David Aparicio and Juan R. Ortigosa and Kevin P. Guay and Robert V. Williams and Jorge O. Lannot and Guanghui Zong and Natalia Comino and José F. Rodríguez and Lai-Xi Wang and Marcelo A. Martí and Pietro Roversi and Daniel N. Hebert and Lila M. Gierasch and Carlos P. Modenutti and Marcelo E. Guerin},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2621329123},
url = {https://doi.org/10.1073/pnas.2621329123},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Structural basis of glycoprotein recognition by the human folding sensor UDP-glucose:glycoprotein glucosyltransferase
AU - David Aparicio
AU - Juan R. Ortigosa
AU - Kevin P. Guay
AU - Robert V. Williams
AU - Jorge O. Lannot
AU - Guanghui Zong
AU - Natalia Comino
AU - José F. Rodríguez
AU - Lai-Xi Wang
AU - Marcelo A. Martí
AU - Pietro Roversi
AU - Daniel N. Hebert
AU - Lila M. Gierasch
AU - Carlos P. Modenutti
AU - Marcelo E. Guerin
PY - 2026
DA - 2026/10/30
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2621329123
UR - https://doi.org/10.1073/pnas.2621329123
AB - UDP-glucose:glycoprotein glucosyltransferase 1 (UGGT1) plays a central role in quality control of glycoprotein folding within the early secretory pathway, yet the molecular basis of UGGT1 substrate recognition remains poorly understood. Here, we report cryo-EM structures of human full-length multidomain UGGT1. Monomeric UGGT1 structures reveal two conformational states corresponding to “open” and “closed” architectures. Three-dimensional variability and molecular dynamics simulations suggest the existence of intermediate conformations, leading to a model in which a continuum of structural transitions underlies UGGT1 function. Notably, in the open state, the EM-maps reveal at the top of the U-shaped protein a density that bridges the sensory TRXL2 and the glucosyltransferase catalytic domains, consistent with substrate association. This observation supports a mode of binding that places the substrate near the catalytic domain. A dimeric form of UGGT1 was observed in which the glycoprotein substrate binding sites are occluded, suggesting that dimerization may regulate UGGT1 activity. To better understand the spatial relationship between the site of misfolding and that of UGGT-mediated N-glycan reglucosylation, we identified N-glycosylation sites on endogenous glycoprotein substrates by glycoproteomics. No consensus sequence was found flanking modified sites, indicating that substrate recognition relies on mechanisms beyond primary sequence. Mutations in the UGGT1 gene cause a novel congenital disorder of glycosylation characterized by developmental delay and intellectual disability, and the human UGGT1 structure helps explain how disease-associated missense and deletion variants disrupt function. Together, our data provide insight into the relationship between UGGT1 structure and function, integrating enzyme conformational states with client glycoprotein interaction and processing.
SN - 0027-8424
SN - 1091-6490
ER -