Cryo-EM structure provides insights into the dimer arrangement of the O-linked β-N-acetylglucosamine transferase OGT

• Published in: Nature communications Vol. 12; no. 1; pp. 6508 - 10
• Main Authors: Meek, Richard W., Blaza, James N., Busmann, Jil A., Alteen, Matthew G., Vocadlo, David J., Davies, Gideon J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 11.11.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 101/28; 631/45/221; 631/45/607/1172; 631/535/1258/1259; Amino Acids - chemistry; Amino Acids - metabolism; Chromium - chemistry; Chromium - metabolism; Cryoelectron Microscopy - methods; Crystallography; Crystallography, X-Ray; Dimers; Glycomics; Glycosyltransferase; Heterogeneity; Humanities and Social Sciences; Intellectual disabilities; Molecular structure; multidisciplinary; Mutation; Mutation - genetics; N-Acetylglucosamine; Neurodegeneration; Nicotinic Acids - chemistry; Nicotinic Acids - metabolism; O-GlcNAcylation; Protein Structure, Secondary; Proteins; Science; Science (multidisciplinary); X-ray crystallography
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26796-6

The O-linked β-N-acetylglucosamine modification is a core signalling mechanism, with erroneous patterns leading to cancer and neurodegeneration. Although thousands of proteins are subject to this modification, only a single essential glycosyltransferase catalyses its installation, the O-GlcNAc transferase, OGT. Previous studies have provided truncated structures of OGT through X-ray crystallography, but the full-length protein has never been observed. Here, we report a 5.3 Å cryo-EM model of OGT. We show OGT is a dimer, providing a structural basis for how some X-linked intellectual disability mutations at the interface may contribute to disease. We observe that the catalytic section of OGT abuts a 13.5 tetratricopeptide repeat unit region and find the relative positioning of these sections deviate from the previously proposed, X-ray crystallography-based model. We also note that OGT exhibits considerable heterogeneity in tetratricopeptide repeat units N-terminal to the dimer interface with repercussions for how OGT binds protein ligands and partners. The modification of proteins with O-linked β-N-acetylglucosamine (OGlcNAc) plays roles in regulation of numerous cellular functions while incorrect O-GlcNAcylation patterns are linked to disease. Here, the authors report a cryo-EM structure of full-length O-GlcNAc transferase (OGT), the only enzyme responsible for O-GlcNAcylation.