1
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Authier F, Ondruskova N, Ferenbach AT, McNeilly AD, van Aalten DMF. Neurodevelopmental defects in a mouse model of O-GlcNAc transferase intellectual disability. Dis Model Mech 2024; 17:dmm050671. [PMID: 38566589 PMCID: PMC11095632 DOI: 10.1242/dmm.050671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/15/2024] [Indexed: 04/04/2024] Open
Abstract
The addition of O-linked β-N-acetylglucosamine (O-GlcNAc) to proteins (referred to as O-GlcNAcylation) is a modification that is crucial for vertebrate development. O-GlcNAcylation is catalyzed by O-GlcNAc transferase (OGT) and reversed by O-GlcNAcase (OGA). Missense variants of OGT have recently been shown to segregate with an X-linked syndromic form of intellectual disability, OGT-linked congenital disorder of glycosylation (OGT-CDG). Although the existence of OGT-CDG suggests that O-GlcNAcylation is crucial for neurodevelopment and/or cognitive function, the underlying pathophysiologic mechanisms remain unknown. Here we report a mouse line that carries a catalytically impaired OGT-CDG variant. These mice show altered O-GlcNAc homeostasis with decreased global O-GlcNAcylation and reduced levels of OGT and OGA in the brain. Phenotypic characterization of the mice revealed lower body weight associated with reduced body fat mass, short stature and microcephaly. This mouse model will serve as an important tool to study genotype-phenotype correlations in OGT-CDG in vivo and for the development of possible treatment avenues for this disorder.
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Affiliation(s)
- Florence Authier
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Nina Ondruskova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, 128 08 Praha 2, Czech Republic
| | - Andrew T. Ferenbach
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Alison D. McNeilly
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee DD1 9SY, UK
| | - Daan M. F. van Aalten
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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2
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Lu P, Liu Y, He M, Cao T, Yang M, Qi S, Yu H, Gao H. Cryo-EM structure of human O-GlcNAcylation enzyme pair OGT-OGA complex. Nat Commun 2023; 14:6952. [PMID: 37907462 PMCID: PMC10618255 DOI: 10.1038/s41467-023-42427-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 10/10/2023] [Indexed: 11/02/2023] Open
Abstract
O-GlcNAcylation is a conserved post-translational modification that attaches N-acetyl glucosamine (GlcNAc) to myriad cellular proteins. In response to nutritional and hormonal signals, O-GlcNAcylation regulates diverse cellular processes by modulating the stability, structure, and function of target proteins. Dysregulation of O-GlcNAcylation has been implicated in the pathogenesis of cancer, diabetes, and neurodegeneration. A single pair of enzymes, the O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), catalyzes the addition and removal of O-GlcNAc on over 3,000 proteins in the human proteome. However, how OGT selects its native substrates and maintains the homeostatic control of O-GlcNAcylation of so many substrates against OGA is not fully understood. Here, we present the cryo-electron microscopy (cryo-EM) structures of human OGT and the OGT-OGA complex. Our studies reveal that OGT forms a functionally important scissor-shaped dimer. Within the OGT-OGA complex structure, a long flexible OGA segment occupies the extended substrate-binding groove of OGT and positions a serine for O-GlcNAcylation, thus preventing OGT from modifying other substrates. Conversely, OGT disrupts the functional dimerization of OGA and occludes its active site, resulting in the blocking of access by other substrates. This mutual inhibition between OGT and OGA may limit the futile O-GlcNAcylation cycles and help to maintain O-GlcNAc homeostasis.
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Affiliation(s)
- Ping Lu
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
| | - Yusong Liu
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Fudan University, Shanghai, China
| | - Maozhou He
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
| | - Ting Cao
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
| | - Mengquan Yang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
| | - Shutao Qi
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
| | - Hongtao Yu
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
| | - Haishan Gao
- New Cornerstone Science Laboratory, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
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3
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Omelková M, Fenger CD, Murray M, Hammer TB, Pravata VM, Bartual SG, Czajewski I, Bayat A, Ferenbach AT, Stavridis MP, van Aalten DMF. An O-GlcNAc transferase pathogenic variant linked to intellectual disability affects pluripotent stem cell self-renewal. Dis Model Mech 2023; 16:dmm049132. [PMID: 37334838 DOI: 10.1242/dmm.049132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 04/19/2023] [Indexed: 06/21/2023] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) is an essential enzyme that modifies proteins with O-GlcNAc. Inborn OGT genetic variants were recently shown to mediate a novel type of congenital disorder of glycosylation (OGT-CDG), which is characterised by X-linked intellectual disability (XLID) and developmental delay. Here, we report an OGTC921Y variant that co-segregates with XLID and epileptic seizures, and results in loss of catalytic activity. Colonies formed by mouse embryonic stem cells carrying OGTC921Y showed decreased levels of protein O-GlcNAcylation accompanied by decreased levels of Oct4 (encoded by Pou5f1), Sox2 and extracellular alkaline phosphatase (ALP), implying reduced self-renewal capacity. These data establish a link between OGT-CDG and embryonic stem cell self-renewal, providing a foundation for examining the developmental aetiology of this syndrome.
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Affiliation(s)
- Michaela Omelková
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Christina Dühring Fenger
- Department of Epilepsy Genetics, Filadelfia Danish Epilepsy Centre, Dianalund 4293, Denmark
- Amplexa Genetics A/S, Odense 5000, Denmark
| | - Marta Murray
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Trine Bjørg Hammer
- Department of Epilepsy Genetics, Filadelfia Danish Epilepsy Centre, Dianalund 4293, Denmark
| | - Veronica M Pravata
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Sergio Galan Bartual
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus 8000, Denmark
| | - Ignacy Czajewski
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Allan Bayat
- Department of Epilepsy Genetics, Filadelfia Danish Epilepsy Centre, Dianalund 4293, Denmark
| | - Andrew T Ferenbach
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus 8000, Denmark
| | - Marios P Stavridis
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Daan M F van Aalten
- Division of Molecular, Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Institute of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha 410008, China
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus 8000, Denmark
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4
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Wenzel DM, Olivier-Van Stichelen S. The O-GlcNAc cycling in neurodevelopment and associated diseases. Biochem Soc Trans 2022; 50:1693-1702. [PMID: 36383066 PMCID: PMC10462390 DOI: 10.1042/bst20220539] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/18/2022] [Accepted: 10/20/2022] [Indexed: 11/18/2022]
Abstract
Proper neuronal development is essential to growth and adult brain function. Alterations at any step of this highly organized sequence of events, due to genetic mutations or environmental factors, triggers brain malformations, which are leading causes of diseases including epilepsy, intellectual disabilities, and many others. The role of glycosylation in neuronal development has been emphasized for many years, notably in studying human congenital disorders of glycosylation (CDGs). These diseases highlight that genetic defects in glycosylation pathways are almost always associated with severe neurological abnormalities, suggesting that glycosylation plays an essential role in early brain development. Congenital disorders of O-GlcNAcylation are no exception, and all mutations of the O-GlcNAc transferase (OGT) are associated with X-linked intellectual disabilities (XLID). In addition, mouse models and in vitro mechanistic studies have reinforced the essential role of O-GlcNAcylation in neuronal development and signaling. In this review, we give an overview of the role of O-GlcNAcylation in this critical physiological process and emphasize the consequences of its dysregulation.
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Affiliation(s)
- Dawn M Wenzel
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, U.S.A
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5
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Mitchell CW, Czajewski I, van Aalten DM. Bioinformatic prediction of putative conveyers of O-GlcNAc transferase intellectual disability. J Biol Chem 2022; 298:102276. [PMID: 35863433 PMCID: PMC9428853 DOI: 10.1016/j.jbc.2022.102276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 02/09/2023] Open
Abstract
Protein O-GlcNAcylation is a dynamic posttranslational modification that is catalyzed by the enzyme O-GlcNAc transferase (OGT) and is essential for neurodevelopment and postnatal neuronal function. Missense mutations in OGT segregate with a novel X-linked intellectual disability syndrome, the OGT congenital disorder of glycosylation (OGT-CDG). One hypothesis for the etiology of OGT-CDG is that loss of OGT activity leads to hypo-O-GlcNAcylation of as yet unidentified, specific neuronal proteins, affecting essential embryonic, and postnatal neurodevelopmental processes; however, the identity of these O-GlcNAcylated proteins is not known. Here, we used bioinformatic techniques to integrate sequence conservation, structural data, clinical data, and the available literature to identify 22 candidate proteins that convey OGT-CDG. We found using gene ontology and PANTHER database data that these candidate proteins are involved in diverse processes including Ras/MAPK signaling, translational repression, cytoskeletal dynamics, and chromatin remodeling. We also identify pathogenic missense variants at O-GlcNAcylation sites that segregate with intellectual disability. This work establishes a preliminary platform for the mechanistic dissection of the links between protein O-GlcNAcylation and neurodevelopment in OGT-CDG.
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Affiliation(s)
- Conor W. Mitchell
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ignacy Czajewski
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Daan M.F. van Aalten
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom,For correspondence: Daan M. F. van Aalten
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6
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Fenckova M, Muha V, Mariappa D, Catinozzi M, Czajewski I, Blok LER, Ferenbach AT, Storkebaum E, Schenck A, van Aalten DMF. Intellectual disability-associated disruption of O-GlcNAc cycling impairs habituation learning in Drosophila. PLoS Genet 2022; 18:e1010159. [PMID: 35500025 PMCID: PMC9140282 DOI: 10.1371/journal.pgen.1010159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 05/27/2022] [Accepted: 03/21/2022] [Indexed: 11/19/2022] Open
Abstract
O-GlcNAcylation is a reversible co-/post-translational modification involved in a multitude of cellular processes. The addition and removal of the O-GlcNAc modification is controlled by two conserved enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA). Mutations in OGT have recently been discovered to cause a novel Congenital Disorder of Glycosylation (OGT-CDG) that is characterized by intellectual disability. The mechanisms by which OGT-CDG mutations affect cognition remain unclear. We manipulated O-GlcNAc transferase and O-GlcNAc hydrolase activity in Drosophila and demonstrate an important role of O-GlcNAcylation in habituation learning and synaptic development at the larval neuromuscular junction. Introduction of patient-specific missense mutations into Drosophila O-GlcNAc transferase using CRISPR/Cas9 gene editing leads to deficits in locomotor function and habituation learning. The habituation deficit can be corrected by blocking O-GlcNAc hydrolysis, indicating that OGT-CDG mutations affect cognition-relevant habituation via reduced protein O-GlcNAcylation. This study establishes a critical role for O-GlcNAc cycling and disrupted O-GlcNAc transferase activity in cognitive dysfunction, and suggests that blocking O-GlcNAc hydrolysis is a potential strategy to treat OGT-CDG.
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Affiliation(s)
- Michaela Fenckova
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Villo Muha
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Daniel Mariappa
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marica Catinozzi
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Ignacy Czajewski
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Laura E. R. Blok
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Andrew T. Ferenbach
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Erik Storkebaum
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Daan M. F. van Aalten
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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7
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Meek RW, Blaza JN, Busmann JA, Alteen MG, Vocadlo DJ, Davies GJ. Cryo-EM structure provides insights into the dimer arrangement of the O-linked β-N-acetylglucosamine transferase OGT. Nat Commun 2021; 12:6508. [PMID: 34764280 PMCID: PMC8586251 DOI: 10.1038/s41467-021-26796-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 10/20/2021] [Indexed: 01/17/2023] Open
Abstract
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.
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Affiliation(s)
- Richard W Meek
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK
| | - James N Blaza
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK.
| | - Jil A Busmann
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Matthew G Alteen
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - David J Vocadlo
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Gideon J Davies
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK.
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8
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Ramirez DH, Yang B, D'Souza AK, Shen D, Woo CM. Truncation of the TPR domain of OGT alters substrate and glycosite selection. Anal Bioanal Chem 2021; 413:7385-7399. [PMID: 34725712 DOI: 10.1007/s00216-021-03731-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 09/25/2021] [Accepted: 10/11/2021] [Indexed: 10/19/2022]
Abstract
O-GlcNAc transferase (OGT) is an essential enzyme that installs O-linked N-acetylglucosamine (O-GlcNAc) to thousands of protein substrates. OGT and its isoforms select from these substrates through the tetratricopeptide repeat (TPR) domain, yet the impact of truncations to the TPR domain on substrate and glycosite selection is unresolved. Here, we report the effects of iterative truncations to the TPR domain of OGT on substrate and glycosite selection with the model protein GFP-JunB and the surrounding O-GlcNAc proteome in U2OS cells. Iterative truncation of the TPR domain of OGT maintains glycosyltransferase activity but alters subcellular localization of OGT in cells. The glycoproteome and glycosites modified by four OGT TPR isoforms were examined on the whole proteome and a single target protein, GFP-JunB. We found the greatest changes in O-GlcNAc on proteins associated with mRNA splicing processes and that the first four TPRs of the canonical nucleocytoplasmic OGT had the broadest substrate scope. Subsequent glycosite analysis revealed that alteration to the last four TPRs corresponded to the greatest shift in the resulting O-GlcNAc consensus sequence. This dataset provides a foundation to analyze how perturbations to the TPR domain and expression of OGT isoforms affect the glycosylation of substrates, which will be critical for future efforts in protein engineering of OGT, the biology of OGT isoforms, and diseases associated with the TPR domain of OGT.
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Affiliation(s)
- Daniel H Ramirez
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.,Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
| | - Bo Yang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Alexandria K D'Souza
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Dacheng Shen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Christina M Woo
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
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9
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Juárez-Jiménez J, Tew P, O Connor M, Llabrés S, Sage R, Glowacki D, Michel J. Combining Virtual Reality Visualization with Ensemble Molecular Dynamics to Study Complex Protein Conformational Changes. J Chem Inf Model 2020; 60:6344-6354. [PMID: 33180485 DOI: 10.1021/acs.jcim.0c00221] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Molecular dynamics (MD) simulations are increasingly used to elucidate relationships between protein structure, dynamics, and their biological function. Currently, it is extremely challenging to perform MD simulations of large-scale structural rearrangements in proteins that occur on millisecond timescales or beyond, as this requires very significant computational resources, or the use of cumbersome "collective variable" enhanced sampling protocols. Here, we describe a framework that combines ensemble MD simulations and virtual reality visualization (eMD-VR) to enable users to interactively generate realistic descriptions of large amplitude, millisecond timescale protein conformational changes in proteins. Detailed tests demonstrate that eMD-VR substantially decreases the computational cost of folding simulations of a WW domain, without the need to define collective variables a priori. We further show that eMD-VR generated pathways can be combined with Markov state models to describe the thermodynamics and kinetics of large-scale loop motions in the enzyme cyclophilin A. Our results suggest eMD-VR is a powerful tool for exploring protein energy landscapes in bioengineering efforts.
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Affiliation(s)
- Jordi Juárez-Jiménez
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - Philip Tew
- Interactive Scientific, Engine Shed, Station Approach, Bristol BS1 6QH, United Kingdom
| | - Michael O Connor
- Intangible Realities Laboratory, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.,Department of Computer Science, University of Bristol, Merchant Venture's Building, Bristol BS8 1UB, United Kingdom.,Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Salomé Llabrés
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - Rebecca Sage
- Interactive Scientific, Engine Shed, Station Approach, Bristol BS1 6QH, United Kingdom
| | - David Glowacki
- Intangible Realities Laboratory, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom.,Department of Computer Science, University of Bristol, Merchant Venture's Building, Bristol BS8 1UB, United Kingdom.,Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Julien Michel
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
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10
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Moll T, Shaw PJ, Cooper-Knock J. Disrupted glycosylation of lipids and proteins is a cause of neurodegeneration. Brain 2020; 143:1332-1340. [PMID: 31724708 PMCID: PMC7241952 DOI: 10.1093/brain/awz358] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022] Open
Abstract
Glycosyltransferases represent a large family of enzymes that catalyse the biosynthesis of oligosaccharides, polysaccharides, and glycoconjugates. A number of studies have implicated glycosyltransferases in the pathogenesis of neurodegenerative diseases but differentiating cause from effect has been difficult. We have recently discovered that mutations proximal to the substrate binding site of glycosyltransferase 8 domain containing 1 (GLT8D1) are associated with familial amyotrophic lateral sclerosis (ALS). We demonstrated that ALS-associated mutations reduce activity of the enzyme suggesting a loss-of-function mechanism that is an attractive therapeutic target. Our work is the first evidence that isolated dysfunction of a glycosyltransferase is sufficient to cause a neurodegenerative disease, but connection between neurodegeneration and genetic variation within glycosyltransferases is not new. Previous studies have identified associations between mutations in UGT8 and sporadic ALS, and between ST6GAL1 mutations and conversion of mild cognitive impairment into clinical Alzheimer’s disease. In this review we consider potential mechanisms connecting glycosyltransferase dysfunction to neurodegeneration. The most prominent candidates are ganglioside synthesis and impaired addition of O-linked β-N-acetylglucosamine (O-GlcNAc) groups to proteins important for axonal and synaptic function. Special consideration is given to examples where genetic mutations within glycosyltransferases are associated with neurodegeneration in recognition of the fact that these changes are likely to be upstream causes present from birth.
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Affiliation(s)
- Tobias Moll
- Sheffield Institute for Translational Neuroscience (SITraN), Sheffield, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience (SITraN), Sheffield, UK
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11
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Estevez A, Zhu D, Blankenship C, Jiang J. Molecular Interrogation to Crack the Case of O-GlcNAc. Chemistry 2020; 26:12086-12100. [PMID: 32207184 PMCID: PMC7724648 DOI: 10.1002/chem.202000155] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 02/28/2020] [Indexed: 12/25/2022]
Abstract
The O-linked β-N-acetylglucosamine (O-GlcNAc) modification, termed O-GlcNAcylation, is an essential and dynamic post-translational modification in cells. O-GlcNAc transferase (OGT) installs this modification on serine and threonine residues, whereas O-GlcNAcase (OGA) hydrolyzes it. O-GlcNAc modifications are found on thousands of intracellular proteins involved in diverse biological processes. Dysregulation of O-GlcNAcylation and O-GlcNAc cycling enzymes has been detected in many diseases, including cancer, diabetes, cardiovascular and neurodegenerative diseases. Here, recent advances in the development of molecular tools to investigate OGT and OGA functions and substrate recognition are discussed. New chemical approaches to study O-GlcNAc dynamics and its potential roles in the immune system are also highlighted. It is hoped that this minireview will encourage more research in these areas to advance the understanding of O-GlcNAc in biology and diseases.
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Affiliation(s)
- Arielis Estevez
- Pharmaceutical Sciences Division, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Dongsheng Zhu
- Pharmaceutical Sciences Division, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Connor Blankenship
- Pharmaceutical Sciences Division, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jiaoyang Jiang
- Pharmaceutical Sciences Division, University of Wisconsin-Madison, Madison, WI, 53705, USA
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12
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Chatham JC, Zhang J, Wende AR. Role of O-Linked N-Acetylglucosamine Protein Modification in Cellular (Patho)Physiology. Physiol Rev 2020; 101:427-493. [PMID: 32730113 DOI: 10.1152/physrev.00043.2019] [Citation(s) in RCA: 146] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the mid-1980s, the identification of serine and threonine residues on nuclear and cytoplasmic proteins modified by a N-acetylglucosamine moiety (O-GlcNAc) via an O-linkage overturned the widely held assumption that glycosylation only occurred in the endoplasmic reticulum, Golgi apparatus, and secretory pathways. In contrast to traditional glycosylation, the O-GlcNAc modification does not lead to complex, branched glycan structures and is rapidly cycled on and off proteins by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. Since its discovery, O-GlcNAcylation has been shown to contribute to numerous cellular functions, including signaling, protein localization and stability, transcription, chromatin remodeling, mitochondrial function, and cell survival. Dysregulation in O-GlcNAc cycling has been implicated in the progression of a wide range of diseases, such as diabetes, diabetic complications, cancer, cardiovascular, and neurodegenerative diseases. This review will outline our current understanding of the processes involved in regulating O-GlcNAc turnover, the role of O-GlcNAcylation in regulating cellular physiology, and how dysregulation in O-GlcNAc cycling contributes to pathophysiological processes.
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Affiliation(s)
- John C Chatham
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama; and Birmingham Veterans Affairs Medical Center, Birmingham, Alabama
| | - Jianhua Zhang
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama; and Birmingham Veterans Affairs Medical Center, Birmingham, Alabama
| | - Adam R Wende
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama; and Birmingham Veterans Affairs Medical Center, Birmingham, Alabama
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13
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Ju Kim E. O‐GlcNAc Transferase: Structural Characteristics, Catalytic Mechanism and Small‐Molecule Inhibitors. Chembiochem 2020; 21:3026-3035. [DOI: 10.1002/cbic.202000194] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/07/2020] [Indexed: 12/21/2022]
Affiliation(s)
- Eun Ju Kim
- Department of Science Education-Chemistry Major Daegu University Gyeongsan-si, GyeongBuk 712-714 South Korea
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14
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Pravata VM, Omelková M, Stavridis MP, Desbiens CM, Stephen HM, Lefeber DJ, Gecz J, Gundogdu M, Õunap K, Joss S, Schwartz CE, Wells L, van Aalten DMF. An intellectual disability syndrome with single-nucleotide variants in O-GlcNAc transferase. Eur J Hum Genet 2020; 28:706-714. [PMID: 32080367 PMCID: PMC7253464 DOI: 10.1038/s41431-020-0589-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 12/30/2019] [Accepted: 02/04/2020] [Indexed: 01/05/2023] Open
Abstract
Intellectual disability (ID) is a neurodevelopmental condition that affects ~1% of the world population. In total 5-10% of ID cases are due to variants in genes located on the X chromosome. Recently, variants in OGT have been shown to co-segregate with X-linked intellectual disability (XLID) in multiple families. OGT encodes O-GlcNAc transferase (OGT), an essential enzyme that catalyses O-linked glycosylation with β-N-acetylglucosamine (O-GlcNAc) on serine/threonine residues of thousands of nuclear and cytosolic proteins. In this review, we compile the work from the last few years that clearly delineates a new syndromic form of ID, which we propose to classify as a novel Congenital Disorder of Glycosylation (OGT-CDG). We discuss potential hypotheses for the underpinning molecular mechanism(s) that provide impetus for future research studies geared towards informed interventions.
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Affiliation(s)
- Veronica M. Pravata
- 0000 0004 0397 2876grid.8241.fDivision of Gene Regulation and Expression and School of Life Sciences, University of Dundee, Dundee, UK
| | - Michaela Omelková
- 0000 0004 0397 2876grid.8241.fDivision of Gene Regulation and Expression and School of Life Sciences, University of Dundee, Dundee, UK
| | - Marios P. Stavridis
- 0000 0004 0397 2876grid.8241.fDivision of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Chelsea M. Desbiens
- 0000 0004 1936 738Xgrid.213876.9Department of Biochemistry and Molecular Biology and Chemistry, Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
| | - Hannah M. Stephen
- 0000 0004 1936 738Xgrid.213876.9Department of Biochemistry and Molecular Biology and Chemistry, Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
| | - Dirk J. Lefeber
- 0000 0004 0444 9382grid.10417.33Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Jozef Gecz
- 0000 0004 1936 7304grid.1010.0Adelaide Medical School and the Robinson Research Institute, The University of Adelaide, Adelaide, SA Australia
| | - Mehmet Gundogdu
- 0000 0001 2193 314Xgrid.8756.cInstitute of Molecular Cell and System Biology, University of Glasgow, Glasgow, UK
| | - Katrin Õunap
- 0000 0001 0585 7044grid.412269.aDepartment of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia ,0000 0001 0943 7661grid.10939.32Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Shelagh Joss
- West of Scotland Genetic Service, Queen Elizabeth University Hospital, Glasgow, UK
| | - Charles E. Schwartz
- 0000 0000 8571 0933grid.418307.9Greenwood Genetic Center, Greenwood, SC 29646 USA
| | - Lance Wells
- 0000 0004 1936 738Xgrid.213876.9Department of Biochemistry and Molecular Biology and Chemistry, Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
| | - Daan M. F. van Aalten
- 0000 0004 0397 2876grid.8241.fDivision of Gene Regulation and Expression and School of Life Sciences, University of Dundee, Dundee, UK ,0000 0001 0379 7164grid.216417.7Institute of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, China
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15
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Moreno-Morcillo M, Francisco-Velilla R, Embarc-Buh A, Fernández-Chamorro J, Ramón-Maiques S, Martinez-Salas E. Structural basis for the dimerization of Gemin5 and its role in protein recruitment and translation control. Nucleic Acids Res 2020; 48:788-801. [PMID: 31799608 PMCID: PMC6954437 DOI: 10.1093/nar/gkz1126] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/12/2019] [Accepted: 11/18/2019] [Indexed: 12/21/2022] Open
Abstract
In all organisms, a selected type of proteins accomplishes critical roles in cellular processes that govern gene expression. The multifunctional protein Gemin5 cooperates in translation control and ribosome binding, besides acting as the RNA-binding protein of the survival of motor neuron (SMN) complex. While these functions reside on distinct domains located at each end of the protein, the structure and function of the middle region remained unknown. Here, we solved the crystal structure of an extended tetratricopeptide (TPR)-like domain in human Gemin5 that self-assembles into a previously unknown canoe-shaped dimer. We further show that the dimerization module is functional in living cells driving the interaction between the viral-induced cleavage fragment p85 and the full-length Gemin5, which anchors splicing and translation members. Disruption of the dimerization surface by a point mutation in the TPR-like domain prevents this interaction and also abrogates translation enhancement induced by p85. The characterization of this unanticipated dimerization domain provides the structural basis for a role of the middle region of Gemin5 as a central hub for protein-protein interactions.
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Affiliation(s)
- María Moreno-Morcillo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain
| | | | - Azman Embarc-Buh
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain
| | | | - Santiago Ramón-Maiques
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER)- Instituto de Salud Carlos III, Valencia, Spain
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16
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Llabrés S, Tsenkov MI, MacGowan SA, Barton GJ, Zachariae U. Disease related single point mutations alter the global dynamics of a tetratricopeptide (TPR) α-solenoid domain. J Struct Biol 2020; 209:107405. [PMID: 31628985 PMCID: PMC6961204 DOI: 10.1016/j.jsb.2019.107405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/04/2019] [Accepted: 10/15/2019] [Indexed: 01/18/2023]
Abstract
Tetratricopeptide repeat (TPR) proteins belong to the class of α-solenoid proteins, in which repetitive units of α-helical hairpin motifs stack to form superhelical, often highly flexible structures. TPR domains occur in a wide variety of proteins, and perform key functional roles including protein folding, protein trafficking, cell cycle control and post-translational modification. Here, we look at the TPR domain of the enzyme O-linked GlcNAc-transferase (OGT), which catalyses O-GlcNAcylation of a broad range of substrate proteins. A number of single-point mutations in the TPR domain of human OGT have been associated with the disease Intellectual Disability (ID). By extended steered and equilibrium atomistic simulations, we show that the OGT-TPR domain acts as an elastic nanospring, and that each of the ID-related local mutations substantially affect the global dynamics of the TPR domain. Since the nanospring character of the OGT-TPR domain is key to its function in binding and releasing OGT substrates, these changes of its biomechanics likely lead to defective substrate interaction. We find that neutral mutations in the human population, selected by analysis of the gnomAD database, do not incur these changes. Our findings may not only help to explain the ID phenotype of the mutants, but also aid the design of TPR proteins with tailored biomechanical properties.
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Affiliation(s)
- Salomé Llabrés
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK.
| | - Maxim I Tsenkov
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Stuart A MacGowan
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Geoffrey J Barton
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK; Physics, School of Science and Engineering, University of Dundee, Dundee, UK.
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17
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Pravata VM, Gundogdu M, Bartual SG, Ferenbach AT, Stavridis M, Õunap K, Pajusalu S, Žordania R, Wojcik MH, van Aalten DMF. A missense mutation in the catalytic domain of O-GlcNAc transferase links perturbations in protein O-GlcNAcylation to X-linked intellectual disability. FEBS Lett 2019; 594:717-727. [PMID: 31627256 PMCID: PMC7042088 DOI: 10.1002/1873-3468.13640] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 06/25/2019] [Accepted: 10/07/2019] [Indexed: 01/01/2023]
Abstract
X‐linked intellectual disabilities (XLID) are common developmental disorders. The enzyme O‐GlcNAc transferase encoded by OGT, a recently discovered XLID gene, attaches O‐GlcNAc to nuclear and cytoplasmic proteins. As few missense mutations have been described, it is unclear what the aetiology of the patient phenotypes is. Here, we report the discovery of a missense mutation in the catalytic domain of OGT in an XLID patient. X‐ray crystallography reveals that this variant leads to structural rearrangements in the catalytic domain. The mutation reduces in vitro OGT activity on substrate peptides/protein. Mouse embryonic stem cells carrying the mutation reveal reduced O‐GlcNAcase (OGA) and global O‐GlcNAc levels. These data suggest a direct link between changes in the O‐GlcNAcome and intellectual disability observed in patients carrying OGT mutations.
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Affiliation(s)
- Veronica M Pravata
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, UK
| | - Mehmet Gundogdu
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, UK
| | - Sergio G Bartual
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, UK
| | - Andrew T Ferenbach
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, UK
| | - Marios Stavridis
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, UK
| | - Katrin Õunap
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Estonia.,Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Estonia
| | - Sander Pajusalu
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Estonia.,Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Estonia
| | - Riina Žordania
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Estonia
| | - Monica H Wojcik
- Divisions of Newborn Medicine and Genetics and Genomics, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Daan M F van Aalten
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, UK
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18
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King DT, Males A, Davies GJ, Vocadlo DJ. Molecular mechanisms regulating O-linked N-acetylglucosamine (O-GlcNAc)-processing enzymes. Curr Opin Chem Biol 2019; 53:131-144. [PMID: 31654859 DOI: 10.1016/j.cbpa.2019.09.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 12/28/2022]
Abstract
The post-translational modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc) dynamically programmes cellular physiology to maintain homoeostasis and tailor biochemical pathways to meet context-dependent cellular needs. Despite diverse roles of played by O-GlcNAc, only two enzymes act antagonistically to govern its cycling; O-GlcNAc transferase installs the monosaccharide on target proteins, and O-GlcNAc hydrolase removes it. The recent literature has exposed a network of mechanisms regulating these two enzymes to choreograph global, and target-specific, O-GlcNAc cycling in response to cellular stress and nutrient availability. Herein, we amalgamate these emerging mechanisms from a structural and molecular perspective to explore how the cell exerts fine control to regulate O-GlcNAcylation of diverse proteins in a selective fashion.
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Affiliation(s)
- Dustin T King
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Alexandra Males
- Department of Chemistry, University of York, York, YO10 5DD, England
| | - Gideon J Davies
- Department of Chemistry, University of York, York, YO10 5DD, England
| | - David J Vocadlo
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
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19
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Joiner CM, Levine ZG, Aonbangkhen C, Woo CM, Walker S. Aspartate Residues Far from the Active Site Drive O-GlcNAc Transferase Substrate Selection. J Am Chem Soc 2019; 141:12974-12978. [PMID: 31373491 DOI: 10.1021/jacs.9b06061] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
O-GlcNAc is an abundant post-translational modification found on nuclear and cytoplasmic proteins in all metazoans. This modification regulates a wide variety of cellular processes, and elevated O-GlcNAc levels have been implicated in cancer progression. A single essential enzyme, O-GlcNAc transferase (OGT), is responsible for all nucleocytoplasmic O-GlcNAcylation. Understanding how this enzyme chooses its substrates is critical for understanding, and potentially manipulating, its functions. Here we use protein microarray technology and proteome-wide glycosylation profiling to show that conserved aspartate residues in the tetratricopeptide repeat (TPR) lumen of OGT drive substrate selection. Changing these residues to alanines alters substrate selectivity and unexpectedly increases rates of protein glycosylation. Our findings support a model where sites of glycosylation for many OGT substrates are determined by TPR domain contacts to substrate side chains five to fifteen residues C-terminal to the glycosite. In addition to guiding design of inhibitors that target OGT's TPR domain, this information will inform efforts to engineer substrates to explore biological functions.
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Affiliation(s)
- Cassandra M Joiner
- Department of Microbiology , Harvard Medical School , 4 Blackfan Circle , Boston , Massachusetts 02115 , United States
| | - Zebulon G Levine
- Department of Microbiology , Harvard Medical School , 4 Blackfan Circle , Boston , Massachusetts 02115 , United States
| | - Chanat Aonbangkhen
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Christina M Woo
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Suzanne Walker
- Department of Microbiology , Harvard Medical School , 4 Blackfan Circle , Boston , Massachusetts 02115 , United States
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20
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Catalytic deficiency of O-GlcNAc transferase leads to X-linked intellectual disability. Proc Natl Acad Sci U S A 2019; 116:14961-14970. [PMID: 31296563 PMCID: PMC6660750 DOI: 10.1073/pnas.1900065116] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
O-GlcNAc transferase (OGT) is an X-linked gene product that is essential for normal development of the vertebrate embryo. It catalyses the O-GlcNAc posttranslational modification of nucleocytoplasmic proteins and proteolytic maturation of the transcriptional coregulator Host cell factor 1 (HCF1). Recent studies have suggested that conservative missense mutations distal to the OGT catalytic domain lead to X-linked intellectual disability in boys, but it is not clear if this is through changes in the O-GlcNAc proteome, loss of protein-protein interactions, or misprocessing of HCF1. Here, we report an OGT catalytic domain missense mutation in monozygotic female twins (c. X:70779215 T > A, p. N567K) with intellectual disability that allows dissection of these effects. The patients show limited IQ with developmental delay and skewed X-inactivation. Molecular analyses revealed decreased OGT stability and disruption of the substrate binding site, resulting in loss of catalytic activity. Editing this mutation into the Drosophila genome results in global changes in the O-GlcNAc proteome, while in mouse embryonic stem cells it leads to loss of O-GlcNAcase and delayed differentiation down the neuronal lineage. These data imply that catalytic deficiency of OGT could contribute to X-linked intellectual disability.
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21
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Hu CW, Worth M, Li H, Jiang J. Chemical and Biochemical Strategies To Explore the Substrate Recognition of O-GlcNAc-Cycling Enzymes. Chembiochem 2019; 20:312-318. [PMID: 30199580 PMCID: PMC6433133 DOI: 10.1002/cbic.201800481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Indexed: 12/11/2022]
Abstract
The O-linked N-acetylglucosamine (O-GlcNAc) modification is an essential component in cell regulation. A single pair of human enzymes conducts this modification dynamically on a broad variety of proteins: O-GlcNAc transferase (OGT) adds the GlcNAc residue and O-GlcNAcase (OGA) hydrolyzes it. This modification is dysregulated in many diseases, but its exact effect on particular substrates remains unclear. In addition, no apparent sequence motif has been found in the modified proteins, and the factors controlling the substrate specificity of OGT and OGA are largely unknown. In this minireview, we will discuss recent developments in chemical and biochemical methods toward addressing the challenge of OGT and OGA substrate recognition. We hope that the new concepts and knowledge from these studies will promote research in this area to advance understanding of O-GlcNAc regulation in health and disease.
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Affiliation(s)
- Chia-Wei Hu
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin–Madison, 777 Highland Avenue, Madison, WI 53705 (USA)
| | - Matthew Worth
- Department of Chemistry, University of Wisconsin–Madison, 101 University Avenue, Madison, WI 53706 (USA)
| | - Hao Li
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin–Madison, 777 Highland Avenue, Madison, WI 53705 (USA)
| | - Jiaoyang Jiang
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin–Madison, 777 Highland Avenue, Madison, WI 53705 (USA)
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22
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Structural characterization of the O-GlcNAc cycling enzymes: insights into substrate recognition and catalytic mechanisms. Curr Opin Struct Biol 2019; 56:97-106. [PMID: 30708324 DOI: 10.1016/j.sbi.2018.12.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/05/2018] [Indexed: 12/19/2022]
Abstract
Dysregulation of nuclear and cytoplasmic O-linked β-N-acetylglucosamine (O-GlcNAc) cycling is implicated in a range of diseases including diabetes and cancer. This modification maintains cellular homeostasis by regulating several biological processes, such as cell signaling. This highly regulated cycle is governed by two sole essential enzymes, O-GlcNAc transferase and O-GlcNAcase that add O-GlcNAc and remove it from over a thousand substrates, respectively. Until recently, due to lack of structural information, the mechanism of substrate recognition has eluted researchers. Here, we review recent successes in structural characterization of these enzymes and how this information has illuminated key features essential for catalysis and substrate recognition. Additionally, we highlight recent studies which have used this information to expand our understanding of substrate specificity by each enzyme.
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