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Kizuka Y. Regulation of intracellular activity of N-glycan branching enzymes in mammals. J Biol Chem 2024; 300:107471. [PMID: 38879010 DOI: 10.1016/j.jbc.2024.107471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/01/2024] [Accepted: 06/06/2024] [Indexed: 07/07/2024] Open
Abstract
Most proteins in the secretory pathway are glycosylated, and N-glycans are estimated to be attached to over 7000 proteins in humans. As structural variation of N-glycans critically regulates the functions of a particular glycoprotein, it is pivotal to understand how structural diversity of N-glycans is generated in cells. One of the major factors conferring structural variation of N-glycans is the variable number of N-acetylglucosamine branches. These branch structures are biosynthesized by dedicated glycosyltransferases, including GnT-III (MGAT3), GnT-IVa (MGAT4A), GnT-IVb (MGAT4B), GnT-V (MGAT5), and GnT-IX (GnT-Vb, MGAT5B). In addition, the presence or absence of core modification of N-glycans, namely, core fucose (included as an N-glycan branch in this manuscript), synthesized by FUT8, also confers large structural variation on N-glycans, thereby crucially regulating many protein-protein interactions. Numerous biochemical and medical studies have revealed that these branch structures are involved in a wide range of physiological and pathological processes. However, the mechanisms regulating the activity of the biosynthetic glycosyltransferases are yet to be fully elucidated. In this review, we summarize the previous findings and recent updates regarding regulation of the activity of these N-glycan branching enzymes. We hope that such information will help readers to develop a comprehensive overview of the complex system regulating mammalian N-glycan maturation.
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Affiliation(s)
- Yasuhiko Kizuka
- Institute for Glyco-core Research (iGCORE), Gifu University, Gifu, Japan.
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2
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Ng D, Pawling J, Dennis JW. Gene purging and the evolution of Neoave metabolism and longevity. J Biol Chem 2023; 299:105409. [PMID: 37918802 PMCID: PMC10722388 DOI: 10.1016/j.jbc.2023.105409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/19/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023] Open
Abstract
Maintenance of the proteasome requires oxidative phosphorylation (ATP) and mitigation of oxidative damage, in an increasingly dysfunctional relationship with aging. SLC3A2 plays a role on both sides of this dichotomy as an adaptor to SLC7A5, a transporter of branched-chain amino acids (BCAA: Leu, Ile, Val), and to SLC7A11, a cystine importer supplying cysteine to the synthesis of the antioxidant glutathione. Endurance in mammalian muscle depends in part on oxidation of BCAA; however, elevated serum levels are associated with insulin resistance and shortened lifespans. Intriguingly, the evolution of modern birds (Neoaves) has entailed the purging of genes including SLC3A2, SLC7A5, -7, -8, -10, and SLC1A4, -5, largely removing BCAA exchangers and their interacting Na+/Gln symporters in pursuit of improved energetics. Additional gene purging included mitochondrial BCAA aminotransferase (BCAT2), pointing to reduced oxidation of BCAA and increased hepatic conversion to triglycerides and glucose. Fat deposits are anhydrous and highly reduced, maximizing the fuel/weight ratio for prolonged flight, but fat accumulation in muscle cells of aging humans contributes to inflammation and senescence. Duplications of the bidirectional α-ketoacid transporters SLC16A3, SLC16A7, the cystine transporters SLC7A9, SLC7A11, and N-glycan branching enzymes MGAT4B, MGAT4C in Neoaves suggests a shift to the transport of deaminated essential amino acid, and stronger mitigation of oxidative stress supported by the galectin lattice. We suggest that Alfred Lotka's theory of natural selection as a maximum power organizer (PNAS 8:151,1922) made an unusually large contribution to Neoave evolution. Further molecular analysis of Neoaves may reveal novel rewiring with applications for human health and longevity.
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Affiliation(s)
- Deanna Ng
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Judy Pawling
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - James W Dennis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto Ontario, Canada.
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3
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Oka N, Mori S, Ikegaya M, Park EY, Miyazaki T. Crystal structure and sugar-binding ability of the C-terminal domain of N-acetylglucosaminyltransferase IV establish a new carbohydrate-binding module family. Glycobiology 2022; 32:1153-1163. [PMID: 36106687 DOI: 10.1093/glycob/cwac058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/25/2022] [Accepted: 08/25/2022] [Indexed: 01/07/2023] Open
Abstract
N-glycans are modified by glycosyltransferases in the endoplasmic reticulum and Golgi apparatus. N-acetylglucosaminyltransferase IV (GnT-IV) is a Golgi-localized glycosyltransferase that synthesizes complex-type N-glycans in vertebrates. This enzyme attaches N-acetylglucosamine (GlcNAc) to the α-1,3-linked mannose branch of the N-glycan core structure via a β-1,4 linkage. Deficiency of this enzyme is known to cause abnormal cellular functions, making it a vital enzyme for living organisms. However, there has been no report on its 3-dimensional structure to date. Here, we demonstrated that the C-terminal regions (named CBML) of human GnT-IVa and Bombyx mori ortholog have the ability to bind β-N-acetylglucosamine. In addition, we determined the crystal structures of human CBML, B. mori CBML, and its complex with β-GlcNAc at 1.97, 1.47, and 1.15 Å resolutions, respectively, and showed that they adopt a β-sandwich fold, similar to carbohydrate-binding module family 32 (CBM32) proteins. The regions homologous to CBML (≥24% identity) were found in GnT-IV isozymes, GnT-IVb, and GnT-IVc (known as GnT-VI), and the structure of B. mori CBML in complex with β-GlcNAc indicated that the GlcNAc-binding residues were highly conserved among these isozymes. These residues are also conserved with the GlcNAc-binding CBM32 domain of β-N-acetylhexosaminidase NagH from Clostridium perfringens despite the low sequence identity (<20%). Taken together with the phylogenetic analysis, these findings indicate that these CBMLs may be novel CBM family proteins with GlcNAc-binding ability.
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Affiliation(s)
- Nozomi Oka
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Sota Mori
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Marina Ikegaya
- Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Enoch Y Park
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Takatsugu Miyazaki
- Department of Agriculture, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
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Taniguchi N, Okawa Y, Maeda K, Kanto N, Johnson EL, Harada Y. N-glycan branching enzymes involved in cancer, Alzheimer's disease and COPD and future perspectives. Biochem Biophys Res Commun 2022; 633:68-71. [DOI: 10.1016/j.bbrc.2022.09.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 09/06/2022] [Indexed: 12/01/2022]
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Osada N, Nagae M, Nakano M, Hirata T, Kizuka Y. Examination of differential glycoprotein preferences of N-acetylglucosaminyltransferase-IV isozymes a and b. J Biol Chem 2022; 298:102400. [PMID: 35988645 PMCID: PMC9478453 DOI: 10.1016/j.jbc.2022.102400] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 08/11/2022] [Accepted: 08/11/2022] [Indexed: 01/23/2023] Open
Abstract
The N-glycans attached to proteins contain various N-acetylglucosamine (GlcNAc) branches, the aberrant formation of which correlates with various diseases. N-Acetylglucosaminyltransferase-IVa (GnT-IVa or MGAT4A) and -IVb (GnT-IVb or MGAT4B) are isoenzymes that catalyze the formation of the β1,4-GlcNAc branch in N-glycans. However, the functional differences between these isozymes remain unresolved. Here, using cellular and UDP-Glo enzyme assays, we discovered that GnT-IVa and GnT-IVb have distinct glycoprotein preferences both in cells and in vitro. Notably, we show GnT-IVb acted efficiently on glycoproteins bearing an N-glycan pre-modified by GnT-IV. To further understand the mechanism of this reaction, we focused on the non-catalytic C-terminal lectin domain, which selectively recognizes the product glycans. Replacement of a non-conserved amino acid in the GnT-IVb lectin domain with the corresponding residue in GnT-IVa altered the glycoprotein preference of GnT-IVb to resemble that of GnT-IVa. Our findings demonstrate that the C-terminal lectin domain regulates differential substrate selectivity of GnT-IVa and -IVb, highlighting a new mechanism by which N-glycan branches are formed on glycoproteins.
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Affiliation(s)
- Naoko Osada
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Masamichi Nagae
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan; Laboratory of Molecular Immunology, Immunology Frontier Research Center (iFReC), Osaka University, Suita, Japan
| | - Miyako Nakano
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
| | - Tetsuya Hirata
- Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu, Japan
| | - Yasuhiko Kizuka
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan; Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu, Japan.
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Discovery of a lectin domain that regulates enzyme activity in mouse N-acetylglucosaminyltransferase-IVa (MGAT4A). Commun Biol 2022; 5:695. [PMID: 35854001 PMCID: PMC9296478 DOI: 10.1038/s42003-022-03661-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 06/29/2022] [Indexed: 01/30/2023] Open
Abstract
N-Glycosylation is a common post-translational modification, and the number of GlcNAc branches in N-glycans impacts glycoprotein functions. N-Acetylglucosaminyltransferase-IVa (GnT-IVa, also designated as MGAT4A) forms a β1-4 GlcNAc branch on the α1-3 mannose arm in N-glycans. Downregulation or loss of GnT-IVa causes diabetic phenotypes by dysregulating glucose transporter-2 in pancreatic β-cells. Despite the physiological importance of GnT-IVa, its structure and catalytic mechanism are poorly understood. Here, we identify the lectin domain in mouse GnT-IVa's C-terminal region. The crystal structure of the lectin domain shows structural similarity to a bacterial GlcNAc-binding lectin. Comprehensive glycan binding assay using 157 glycans and solution NMR reveal that the GnT-IVa lectin domain selectively interacts with the product N-glycans having a β1-4 GlcNAc branch. Point mutation of the residue critical to sugar recognition impairs the enzymatic activity, suggesting that the lectin domain is a regulatory subunit for efficient catalytic reaction. Our findings provide insights into how branching structures of N-glycans are biosynthesized.
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Schön K, Lepenies B, Goyette-Desjardins G. Impact of Protein Glycosylation on the Design of Viral Vaccines. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2021; 175:319-354. [PMID: 32935143 DOI: 10.1007/10_2020_132] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glycans play crucial roles in various biological processes such as cell proliferation, cell-cell interactions, and immune responses. Since viruses co-opt cellular biosynthetic pathways, viral glycosylation mainly depends on the host cell glycosylation machinery. Consequently, several viruses exploit the cellular glycosylation pathway to their advantage. It was shown that viral glycosylation is strongly dependent on the host system selected for virus propagation and/or protein expression. Therefore, the use of different expression systems results in various glycoforms of viral glycoproteins that may differ in functional properties. These differences clearly illustrate that the choice of the expression system can be important, as the resulting glycosylation may influence immunological properties. In this review, we will first detail protein N- and O-glycosylation pathways and the resulting glycosylation patterns; we will then discuss different aspects of viral glycosylation in pathogenesis and in vaccine development; and finally, we will elaborate on how to harness viral glycosylation in order to optimize the design of viral vaccines. To this end, we will highlight specific examples to demonstrate how glycoengineering approaches and exploitation of different expression systems could pave the way towards better self-adjuvanted glycan-based viral vaccines.
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Affiliation(s)
- Kathleen Schön
- Immunology Unit and Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Hanover, Germany
- Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Bernd Lepenies
- Immunology Unit and Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Hanover, Germany.
| | - Guillaume Goyette-Desjardins
- Immunology Unit and Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Hanover, Germany.
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Abstract
N-glycosylation is a highly conserved glycan modification, and more than 7000 proteins are N-glycosylated in humans. N-glycosylation has many biological functions such as protein folding, trafficking, and signal transduction. Thus, glycan modification to proteins is profoundly involved in numerous physiological and pathological processes. The N-glycan precursor is biosynthesized in the endoplasmic reticulum (ER) from dolichol phosphate by sequential enzymatic reactions to generate the dolichol-linked oligosaccharide composed of 14 sugar residues, Glc3Man9GlcNAc2. The oligosaccharide is then en bloc transferred to the consensus sequence N-X-S/T (X represents any amino acid except proline) of nascent proteins. Subsequently, the N-glycosylated nascent proteins enter the folding step, in which N-glycans contribute largely to attaining the correct protein fold by recruiting the lectin-like chaperones, calnexin, and calreticulin. Despite the N-glycan-dependent folding process, some glycoproteins do not fold correctly, and these misfolded glycoproteins are destined to degradation by proteasomes in the cytosol. Properly folded proteins are transported to the Golgi, and N-glycans undergo maturation by the sequential reactions of glycosidases and glycosyltransferases, generating complex-type N-glycans. N-Acetylglucosaminyltransferases (GnT-III, GnT-IV, and GnT-V) produce branched N-glycan structures, affording a higher complexity to N-glycans. In this chapter, we provide an overview of the biosynthetic pathway of N-glycans in the ER and Golgi.
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de la Ballina NR, Villalba A, Cao A. Differences in proteomic profile between two haemocyte types, granulocytes and hyalinocytes, of the flat oyster Ostrea edulis. FISH & SHELLFISH IMMUNOLOGY 2020; 100:456-466. [PMID: 32205190 DOI: 10.1016/j.fsi.2020.03.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 06/10/2023]
Abstract
Haemocytes play a dominant role in shellfish immunity, being considered the main defence effector cells in molluscs. These cells are known to be responsible for many functions, including chemotaxis, cellular recognition, attachment, aggregation, shell repair and nutrient transport and digestion. There are two basic cell types of bivalve haemocytes morphologically distinguishable, hyalinocytes and granulocytes; however, functional differences and specific abilities are poorly understood: granulocytes are believed to be more efficient in killing microorganisms, while hyalinocytes are thought to be more specialised in clotting and wound healing. A proteomic approach was implemented to find qualitative differences in the protein profile between granulocytes and hyalinocytes of the European flat oyster, Ostrea edulis, as a way to evaluate functional differences. Oyster haemolymph cells were differentially separated by Percoll® density gradient centrifugation. Granulocyte and hyalinocyte proteins were separated by 2D-PAGE and their protein profiles were analysed and compared with PD Quest software; the protein spots exclusive for each haemocyte type were excised from gels and analysed by MALDI-TOF/TOF with a combination of mass spectrometry (MS) and MS/MS for sequencing and protein identification. A total of 34 proteins were identified, 20 unique to granulocytes and 14 to hyalinocytes. The results suggested differences between the haemocyte types in signal transduction, apoptosis, oxidation reduction processes, cytoskeleton, phagocytosis and pathogen recognition. These results contribute to identify differential roles of each haemocyte type and to better understand the oyster immunity mechanisms, which should help to fight oyster diseases.
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Affiliation(s)
- Nuria R de la Ballina
- Centro de Investigacións Mariñas (CIMA), Consellería do Mar, Xunta de Galicia, 36620, Vilanova de Arousa, Spain
| | - Antonio Villalba
- Centro de Investigacións Mariñas (CIMA), Consellería do Mar, Xunta de Galicia, 36620, Vilanova de Arousa, Spain; Departamento de Ciencias de la Vida, Universidad de Alcalá, 28871, Alcalá de Henares, Spain; Research Centre for Experimental Marine Biology and Biotechnology (PIE), University of the Basque Country (UPV/EHU), 48620, Plentzia, Spain.
| | - Asunción Cao
- Centro de Investigacións Mariñas (CIMA), Consellería do Mar, Xunta de Galicia, 36620, Vilanova de Arousa, Spain
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Nagae M, Yamaguchi Y, Taniguchi N, Kizuka Y. 3D Structure and Function of Glycosyltransferases Involved in N-glycan Maturation. Int J Mol Sci 2020; 21:ijms21020437. [PMID: 31936666 PMCID: PMC7014118 DOI: 10.3390/ijms21020437] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 12/21/2022] Open
Abstract
Glycosylation is the most ubiquitous post-translational modification in eukaryotes. N-glycan is attached to nascent glycoproteins and is processed and matured by various glycosidases and glycosyltransferases during protein transport. Genetic and biochemical studies have demonstrated that alternations of the N-glycan structure play crucial roles in various physiological and pathological events including progression of cancer, diabetes, and Alzheimer’s disease. In particular, the formation of N-glycan branches regulates the functions of target glycoprotein, which are catalyzed by specific N-acetylglucosaminyltransferases (GnTs) such as GnT-III, GnT-IVs, GnT-V, and GnT-IX, and a fucosyltransferase, FUT8s. Although the 3D structures of all enzymes have not been solved to date, recent progress in structural analysis of these glycosyltransferases has provided insights into substrate recognition and catalytic reaction mechanisms. In this review, we discuss the biological significance and structure-function relationships of these enzymes.
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Affiliation(s)
- Masamichi Nagae
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
- Correspondence: (M.N.); (Y.K.)
| | - Yoshiki Yamaguchi
- Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Miyagi 981-8558, Japan;
| | - Naoyuki Taniguchi
- Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, 3-1-69 Otemae, Chuo-ku, Osaka 541-8567, Japan;
| | - Yasuhiko Kizuka
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
- Correspondence: (M.N.); (Y.K.)
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Abdel Rahman AM, Ryczko M, Nakano M, Pawling J, Rodrigues T, Johswich A, Taniguchi N, Dennis JW. Golgi N-glycan branching N-acetylglucosaminyltransferases I, V and VI promote nutrient uptake and metabolism. Glycobiology 2014; 25:225-40. [PMID: 25395405 DOI: 10.1093/glycob/cwu105] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Nutrient transporters are critical gate-keepers of extracellular metabolite entry into the cell. As integral membrane proteins, most transporters are N-glycosylated, and the N-glycans are remodeled in the Golgi apparatus. The Golgi branching enzymes N-acetylglucosaminyltransferases I, II, IV, V and avian VI (encoded by Mgat1, Mgat2, Mgat4a/b/c Mgat5 and Mgat6), each catalyze the addition of N-acetylglucosamine (GlcNAc) in N-glycans. Here, we asked whether N-glycan branching promotes nutrient transport and metabolism in immortal human HeLa carcinoma and non-malignant HEK293 embryonic kidney cells. Mgat6 is absent in mammals, but ectopic expression can be expected to add an additional β1,4-linked branch to N-glycans, and may provide evidence for functional redundancy of the N-glycan branches. Tetracycline (tet)-induced overexpression of Mgat1, Mgat5 and Mgat6 resulted in increased enzyme activity and increased N-glycan branching concordant with the known specificities of these enzymes. Tet-induced Mgat1, Mgat5 and Mgat6 combined with stimulation of hexosamine biosynthesis pathway (HBP) to UDP-GlcNAc, increased cellular metabolite levels, lactate and oxidative metabolism in an additive manner. We then tested the hypothesis that N-glycan branching alone might promote nutrient uptake when glucose (Glc) and glutamine are limiting. In low glutamine and Glc medium, tet-induced Mgat5 alone increased amino acids uptake, intracellular levels of glycolytic and TCA intermediates, as well as HEK293 cell growth. More specifically, tet-induced Mgat5 and HBP elevated the import rate of glutamine, although transport of other metabolites may be regulated in parallel. Our results suggest that N-glycan branching cooperates with HBP to regulate metabolite import in a cell autonomous manner, and can enhance cell growth in low-nutrient environments.
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Affiliation(s)
- Anas M Abdel Rahman
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5
| | - Michael Ryczko
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5 Department of Molecular Genetics
| | - Miyako Nakano
- Disease Glycomics Team, Systems Glycobiology Research Group, Chemical Biology Department, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, Wako, Saitama 351-0198, Japan Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima 739-8530, Japan
| | - Judy Pawling
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5
| | - Tania Rodrigues
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5 Department of Molecular Genetics
| | - Anita Johswich
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5
| | - Naoyuki Taniguchi
- Disease Glycomics Team, Systems Glycobiology Research Group, Chemical Biology Department, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, Wako, Saitama 351-0198, Japan
| | - James W Dennis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room #988, Toronto, ON, Canada M5G1X5 Department of Molecular Genetics Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada M5G1X5
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Taguchi T, Taniguchi N. A method for determination of UDP-GlcNAc: GlcNAcβ1-6(GlcNAcβ1-2)Manα1-R [GlcNAc to Man] β1-4N-acetylglucosaminyltransferase VI activity. Methods Mol Biol 2013; 1022:299-305. [PMID: 23765670 DOI: 10.1007/978-1-62703-465-4_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To characterize and purify glycosyltransferases, it is essential to establish a simple and sensitive assay method. Here, we describe a method for determination of the activity of GnT VI (UDP-GlcNAc: GlcNAcβ1-6(GlcNAcβ1-2)Manα1-R [GlcNAc to Man] β1-4N-acetylglucosaminyltransferase VI) using a fluorescently labeled oligosaccharide.
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Affiliation(s)
- Tomohiko Taguchi
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
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Bojarová P, Rosencrantz RR, Elling L, Křen V. Enzymatic glycosylation of multivalent scaffolds. Chem Soc Rev 2013; 42:4774-97. [DOI: 10.1039/c2cs35395d] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Oguri S, Yoshida A, Minowa MT, Takeuchi M. Kinetic properties and substrate specificities of two recombinant human N-acetylglucosaminyltransferase-IV isozymes. Glycoconj J 2006; 23:473-80. [PMID: 17006639 DOI: 10.1007/s10719-006-6216-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 10/26/2005] [Accepted: 11/14/2005] [Indexed: 10/24/2022]
Abstract
N-acetylglucosaminyltransferase (GnT)-IV catalyzes the formation of the GlcNAcbeta1-4 branch on the GlcNAcbeta1-2Manalpha1-3 arm of the core structure of N-glycans. Two human GnT-IV isozymes (GnT-IVa and GnT-IVb) had been identified, which exhibit different expression profiles among human tissues and cancer cell lines. To clarify the enzymatic properties of the respective enzymes, their kinetic parameters were determined using recombinant full-length enzymes expressed in COS7 cells. The K (m) of human GnT-IVb for UDP-GlcNAc was estimated to be 0.24 mM, which is 2-fold higher than that of human GnT-IVa. The K (m) values of GnT-IVb for pyridylaminated (PA) acceptor sugar chains with different branch numbers were 3- to 6-fold higher than those of GnT-IVa. To compare substrate specificities more precisely, we generated recombinant soluble enzymes of human GnT-IVa and GnT-IVb with N-terminal flag tags. Both enzymes showed similar substrate specificities as determined using fourteen PA-sugar chains. They preferred complex-type N-glycans over hybrid-types. Among the complex-type N-glycans tested, the relative activities of both enzymes were increased in proportion to the number of GlcNAc branches on the Man alpha1-6 arm. The Man alpha1-6 arm of the acceptors was not essential for their activities because a linear pentasaccharide lacking this arm, GlcNAcbeta1-2Manalpha1-3Manbeta1-4GlcNAcbeta1-4 GlcNAc-PA, was a substrate for both enzymes. These results indicate that human GnT-IVb exhibits the same acceptor substrate specificities as human GnT-IVa, although GnT-IVb has lower affinities for donors or acceptors than GnT-IVa. This suggests that GnT-IVa is more active than GnT-IVb under physiological conditions and that it primarily contributes to the biosynthesis of N-glycans.
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Affiliation(s)
- Suguru Oguri
- Department of Bioproduction, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan.
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Watanabe T, Ihara H, Miyoshi E, Honke K, Taniguchi N, Taguchi T. A specific detection of GlcNAcbeta1-6Manalpha1 branches in N-linked glycoproteins based on the specificity of N-acetylglucosaminyltransferase VI. Glycobiology 2006; 16:431-9. [PMID: 16428802 DOI: 10.1093/glycob/cwj079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Malignant transformation is often accompanied by an aberrant glycosylation profile of the cell surface-in particular, the production of GlcNAcbeta1-6Manalpha1 branches in N-linked glycoproteins. To identify the target glycoproteins, we show a method using recombinant chicken N-acetylglucosaminyltransferase VI (GnT VI) and radiolabeled uridine (5'-)diphosphate-GlcNAc. The assay exploits the fact that GnT VI has a strict requirement for the GlcNAcbeta1-6Manalpha1 structure for activity, when a pyridylaminated free N-glycan is used as the acceptor substrate. Human asialo-agalacto alpha1-acid glycoprotein (AGP), which is known to contain GlcNAcbeta1-6Manalpha1 branches in its N-linked glycan chains, was radiolabeled when reacted with GnT VI, whereas human asialo-agalacto transferrin and bovine fetuin, neither of which contains a GlcNAcbeta1-6Manalpha1 structure were not, thus corroborating the specificity of the assay. Several proteins from human serum after pretreatment with sialidase and beta-galactosidase could be detected using the assay. One was identified as AGP from its mobility on SDS-PAGE, demonstrating the potential of this assay even with crude materials. Furthermore, this method could detect a protein that was also positively stained with leukoagglutinating phytohemagglutinin (L(4)-PHA) using glycoproteins prepared from WiDr human colon cancer cells. This method should provide a useful complement to the current method, which relies on the specificity of L(4)-PHA.
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Affiliation(s)
- Tae Watanabe
- Department of Biochemistry, Osaka University Graduate School of Medicine 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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16
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Abstract
The four essential building blocks of cells are proteins, nucleic acids, lipids, and glycans. Also referred to as carbohydrates, glycans are composed of saccharides that are typically linked to lipids and proteins in the secretory pathway. Glycans are highly abundant and diverse biopolymers, yet their functions have remained relatively obscure. This is changing with the advent of genetic reagents and techniques that in the past decade have uncovered many essential roles of specific glycan linkages in living organisms. Glycans appear to modulate biological processes in the development and function of multiple physiologic systems, in part by regulating protein-protein and cell-cell interactions. Moreover, dysregulation of glycan synthesis represents the etiology for a growing number of human genetic diseases. The study of glycans, known as glycobiology, has entered an era of renaissance that coincides with the acquisition of complete genome sequences for multiple organisms and an increased focus upon how posttranslational modifications to protein contribute to the complexity of events mediating normal and disease physiology. Glycan production and modification comprise an estimated 1% of genes in the mammalian genome. Many of these genes encode enzymes termed glycosyltransferases and glycosidases that reside in the Golgi apparatus where they play the major role in constructing the glycan repertoire that is found at the cell surface and among extracellular compartments. We present a review of the recently established functions of glycan structures in the context of mammalian genetic studies focused upon the mouse and human species. Nothing tends so much to the advancement of knowledge as the application of a new instrument. The native intellectual powers of men in different times are not so much the causes of the different success of their labours, as the peculiar nature of the means and artificial resources in their possession. T. Hager: Force of Nature (1)
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Affiliation(s)
- John B Lowe
- Department of Pathology and Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan 48109, USA.
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Sasai K, Ikeda Y, Fujii T, Tsuda T, Taniguchi N. UDP-GlcNAc concentration is an important factor in the biosynthesis of beta1,6-branched oligosaccharides: regulation based on the kinetic properties of N-acetylglucosaminyltransferase V. Glycobiology 2002; 12:119-27. [PMID: 11886845 DOI: 10.1093/glycob/12.2.119] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human beta1,6-N-acetylglucosaminyltransferase V (GnT-V) was expressed by baculovirus-insect cell system, and the purified recombinant enzyme was kinetically characterized. The data obtained were used to establish the kinetic basis of the substrate specificity toward donor nucleotide sugars, and also revealed that K(m) values for the donors are much higher compared to those of other GlcNAc transferases, the kinetic properties of which have been reported. Because this exceptionally higher K(m) suggests that GnT-V is physiologically present at far from saturated conditions, it would appear that the production of beta1,6-branched oligosaccharide, which is formed by GnT-V, could be regulated in vivo by the concentration of the donor, UDP-GlcNAc, as well as the expression levels of the enzyme. When B16 melanoma cells, which express high levels of GnT-V, were incubated with GlcNAc, the beta1,6-branched oligosaccharide levels were increased, as judged by a lectin blot analysis, in conjunction with an increase in intracellular UDP-GlcNAc. These findings suggest that the level of UDP-GlcNAc can be a critical factor in the production of beta1,6-branched oligosaccharides, for example, by tumor cells, which have been thought to be closely associated with tumor progression and metastasis.
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Affiliation(s)
- Ken Sasai
- Department of Biochemistry, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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18
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Sakamoto Y, Taguchi T, Honke K, Korekane H, Watanabe H, Tano Y, Dohmae N, Takio K, Horii A, Taniguchi N. Molecular cloning and expression of cDNA encoding chicken UDP-N-acetyl-D-glucosamine (GlcNAc): GlcNAcbeta 1-6(GlcNAcbeta 1-2)- manalpha 1-R[GlcNAc to man]beta 1,4N-acetylglucosaminyltransferase VI. J Biol Chem 2000; 275:36029-34. [PMID: 10962001 DOI: 10.1074/jbc.m005860200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cDNA that encodes UDP-N-acetyl-d-glucosamine (GlcNAc):GlcNAcbeta1-6(GlcNAcbeta1-2)Manalpha1-R[GlcNA c to Man]beta1, 4N-acetylglucosaminyltransferase VI (GnT VI), which is responsible for the formation of pentaantennary asparagine-linked oligosaccharides (N-glycans), has been cloned from a hen oviduct cDNA library based on the partial amino acid sequences of the purified enzyme. The isolated cDNA clone contained an open reading frame encoding 464 amino acids, including all of the peptides that were sequenced. The deduced amino acid sequence predicts a type II transmembrane topology and contains two potential N-glycosylation sites. The primary structure was found to be significantly similar to human GnT IV-homologue, the gene for which was cloned from the deleted region in pancreatic cancer, and to human and bovine GnT IVs. Chicken GnT VI-transfected COS-1 cells showed a high GnT VI activity (26.8 pmol/h/mg protein), whereas nontransfected, mock-transfected, or human GnT IV-homologue-transfected COS-1 cells had no activity. Northern blot analysis using poly(A)(+) RNA from hen oviduct indicated that the size of GnT VI mRNA is 2.1 kilobases. Reverse transcription-polymerase chain reaction analysis showed that GnT VI mRNA was relatively highly expressed in oviduct, spleen, lung, and colon.
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Affiliation(s)
- Y Sakamoto
- Departments of Biochemistry and Ophthalmology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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19
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Abstract
This review covers discoveries made over the past 30-35 years that were important to our understanding of the synthetic pathway required for initiation of the antennae or branches on complex N-glycans and O-glycans. The review deals primarily with the author's contributions but the relevant work of other laboratories is also discussed. The focus of the review is almost entirely on the glycosyltransferases involved in the process. The following topics are discussed. (1) The localization of the synthesis of complex N-glycan antennae to the Golgi apparatus. (2) The "evolutionary boundary" at the stage in N-glycan processing where there is a change from oligomannose to complex N-glycans; this switch correlates with the appearance of multicellular organisms. (3) The discovery of the three enzymes which play a key role in this switch, N-acetylglucosaminyltransferases I and II and mannosidase II. (4) The "yellow brick road" which leads from oligomannose to highly branched complex N-glycans with emphasis on the enzymes involved in the process and the factors which control the routes of synthesis. (5) A short discussion of the characteristics of the enzymes involved and of the genes that encode them. (6) The role of complex N-glycans in mammalian and Caenorhabditis elegans development. (7) The crystal structure of N-acetylglucosaminyltransferase I. (8) The discovery of the enzymes which synthesize O-glycan cores 1, 2, 3 and 4 and their elongation.
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Affiliation(s)
- H Schachter
- Department of Structural Biology and Biochemistry, Research Institute, The Hospital for Sick Children, Faculty of Medicine, University of Toronto, Ont, Canada.
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