University of Oulu

Harrus D, Khoder-Agha F, Peltoniemi M, Hassinen A, Ruddock L, Kellokumpu S, et al. (2018) The dimeric structure of wild-type human glycosyltransferase B4GalT1. PLoS ONE 13(10): e0205571.

The dimeric structure of wild-type human glycosyltransferase B4GalT1

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Author: Harrus, Deborah1; Khoder-Agha, Fawzi1; Peltoniemi, Miika1;
Organizations: 1Faculty of Biochemistry and Molecular Medicine, University of Oulu
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.9 MB)
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Language: English
Published: Public Library of Science, 2018
Publish Date: 2018-11-20


Most glycosyltransferases, including B4GalT1 (EC, are known to assemble into enzyme homomers and functionally relevant heteromers in vivo. However, it remains unclear why and how these enzymes interact at the molecular/atomic level. Here, we solved the crystal structure of the wild-type human B4GalT1 homodimer. We also show that B4GalT1 exists in a dynamic equilibrium between monomer and dimer, since a purified monomer reappears as a mixture of both and as we obtained crystal forms of the monomer and dimer assemblies in the same crystallization conditions. These two crystal forms revealed the unliganded B4GalT1 in both the open and the closed conformation of the Trp loop and the lid regions, responsible for donor and acceptor substrate binding, respectively. The present structures also show the lid region in full in an open conformation, as well as a new conformation for the GlcNAc acceptor loop (residues 272–288). The physiological relevance of the homodimer in the crystal was validated by targeted mutagenesis studies coupled with FRET assays. These showed that changing key catalytic amino acids impaired homomer formation in vivo. The wild-type human B4GalT1 structure also explains why the variant proteins used for crystallization in earlier studies failed to reveal the homodimers described in this study.

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Series: PLoS one
ISSN: 1932-6203
ISSN-E: 1932-6203
ISSN-L: 1932-6203
Volume: 13
Issue: 10
Article number: e0205571
DOI: 10.1371/journal.pone.0205571
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This work has been funded by the Academy of Finland (no. 285232 to Dr. Sakari Kellokumpu), University of Oulu, and Emil Aaltonen Foundation (to Dr. Antti Hassinen).
Academy of Finland Grant Number: 285232
Detailed Information: 285232 (Academy of Finland Funding decision)
Copyright information: © 2018 Harrus et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.