University of Oulu

Khoder-Agha, F., Harrus, D., Brysbaert, G., Lensink, M. F., Harduin-Lepers, A., Glumoff, T., & Kellokumpu, S. (2019). Assembly of B4GALT1/ST6GAL1 heteromers in the Golgi membranes involves lateral interactions via highly charged surface domains. Journal of Biological Chemistry, 294(39), 14383–14393.

Assembly of B4GALT1/ST6GAL1 heteromers in the Golgi membranes involves lateral interactions via highly charged surface domains

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Author: Khoder-Agha, Fawzi1; Harrus, Deborah1; Brysbaert, Guillaume2;
Organizations: 1Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7A, 90220 Oulu, Finland
2Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.6 MB)
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Language: English
Published: American Society for Biochemistry and Molecular Biology, 2019
Publish Date: 2021-10-11


β-1,4-Galactosyltransferase 1 (B4GALT1) and ST6 β-galactoside α-2,6-sialyltransferase 1 (ST6GAL1) catalyze the successive addition of terminal β-1,4–linked galactose and α-2,6–linked sialic acid to N-glycans. Their exclusive interaction in the Golgi compartment is a prerequisite for their full catalytic activity, whereas a lack of this interaction is associated with cancers and hypoxia. To date, no structural information exists that shows how glycosyltransferases functionally assemble with each other. Using molecular docking simulations to predict interaction surfaces, along with mutagenesis screens and high-throughput FRET analyses in live cells to validate these predictions, we show here that B4GALT1 and ST6GAL1 interact via highly charged noncatalytic surfaces, leaving the active sites exposed and accessible for donor and acceptor substrate binding. Moreover, we found that the assembly of ST6GAL1 homomers in the endoplasmic reticulum before ST6GAL1 activation in the Golgi utilizes the same noncatalytic surface, whereas B4GALT1 uses its active-site surface for assembly, which silences its catalytic activity. Last, we show that the homomeric and heteromeric B4GALT1/ST6GAL1 complexes can assemble laterally in the Golgi membranes without forming cross-cisternal contacts between enzyme molecules residing in the opposite membranes of each Golgi cisterna. Our results provide detailed mechanistic insights into the regulation of glycosyltransferase interactions, the transitions between B4GALT1 and ST6GAL1 homo- and heteromers in the Golgi, and cooperative B4GALT1/ST6GAL1 function in N-glycan synthesis.

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Series: Journal of biological chemistry
ISSN: 0021-9258
ISSN-E: 1083-351X
ISSN-L: 0021-9258
Volume: 294
Issue: 39
Pages: 14383 - 14393
DOI: 10.1074/jbc.RA119.009539
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: Thiswork was supported by Academy of Finland Grant 285232 and CNRS.
Academy of Finland Grant Number: 285232
Detailed Information: 285232 (Academy of Finland Funding decision)
Dataset Reference: Cambridge Crystallographic Data Center
Copyright information: © 2019 Khoder-Agha et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc. This is an open access article under the CC BY license.