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A century of exercise physiology: key concepts in regulation of glycogen metabolism in skeletal muscle. Eur J Appl Physiol 2022; 122:1751-1772. [PMID: 35355125 PMCID: PMC9287217 DOI: 10.1007/s00421-022-04935-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 03/15/2022] [Indexed: 01/20/2023]
Abstract
Glycogen is a branched, glucose polymer and the storage form of glucose in cells. Glycogen has traditionally been viewed as a key substrate for muscle ATP production during conditions of high energy demand and considered to be limiting for work capacity and force generation under defined conditions. Glycogenolysis is catalyzed by phosphorylase, while glycogenesis is catalyzed by glycogen synthase. For many years, it was believed that a primer was required for de novo glycogen synthesis and the protein considered responsible for this process was ultimately discovered and named glycogenin. However, the subsequent observation of glycogen storage in the absence of functional glycogenin raises questions about the true role of the protein. In resting muscle, phosphorylase is generally considered to be present in two forms: non-phosphorylated and inactive (phosphorylase b) and phosphorylated and constitutively active (phosphorylase a). Initially, it was believed that activation of phosphorylase during intense muscle contraction was primarily accounted for by phosphorylation of phosphorylase b (activated by increases in AMP) to a, and that glycogen synthesis during recovery from exercise occurred solely through mechanisms controlled by glucose transport and glycogen synthase. However, it now appears that these views require modifications. Moreover, the traditional roles of glycogen in muscle function have been extended in recent years and in some instances, the original concepts have undergone revision. Thus, despite the extensive amount of knowledge accrued during the past 100 years, several critical questions remain regarding the regulation of glycogen metabolism and its role in living muscle.
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Pancha I, Takaya K, Tanaka K, Imamura S. The Unicellular Red Alga Cyanidioschyzon merolae, an Excellent Model Organism for Elucidating Fundamental Molecular Mechanisms and Their Applications in Biofuel Production. PLANTS 2021; 10:plants10061218. [PMID: 34203949 PMCID: PMC8232737 DOI: 10.3390/plants10061218] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022]
Abstract
Microalgae are considered one of the best resources for the production of biofuels and industrially important compounds. Various models have been developed to understand the fundamental mechanism underlying the accumulation of triacylglycerols (TAGs)/starch and to enhance its content in cells. Among various algae, the red alga Cyanidioschyzonmerolae has been considered an excellent model system to understand the fundamental mechanisms behind the accumulation of TAG/starch in the microalga, as it has a smaller genome size and various biotechnological methods are available for it. Furthermore, C. merolae can grow and survive under high temperature (40 °C) and low pH (2–3) conditions, where most other organisms would die, thus making it a choice alga for large-scale production. Investigations using this alga has revealed that the target of rapamycin (TOR) kinase is involved in the accumulation of carbon-reserved molecules, TAGs, and starch. Furthermore, detailed molecular mechanisms of the role of TOR in controlling the accumulation of TAGs and starch were uncovered via omics analyses. Based on these findings, genetic engineering of the key gene and proteins resulted in a drastic increment of the amount of TAGs and starch. In addition to these studies, other trials that attempted to achieve the TAG increment in C. merolae have been summarized in this article.
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Affiliation(s)
- Imran Pancha
- Department of Biological Sciences, SRM University-AP, Amaravati, Andhra Pradesh 522502, India
- Correspondence: (I.P.); (S.I.); Tel.: +81-422-59-6179 (S.I.)
| | - Kazuhiro Takaya
- NTT Space Environment and Energy Laboratories, Nippon Telegraph and Telephone Corporation, 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan;
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1-29 Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Japan;
| | - Sousuke Imamura
- NTT Space Environment and Energy Laboratories, Nippon Telegraph and Telephone Corporation, 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan;
- Correspondence: (I.P.); (S.I.); Tel.: +81-422-59-6179 (S.I.)
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3
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From the seminal discovery of proteoglycogen and glycogenin to emerging knowledge and research on glycogen biology. Biochem J 2019; 476:3109-3124. [DOI: 10.1042/bcj20190441] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/10/2019] [Accepted: 10/14/2019] [Indexed: 11/17/2022]
Abstract
AbstractAlthough the discovery of glycogen in the liver, attributed to Claude Bernard, happened more than 160 years ago, the mechanism involved in the initiation of glucose polymerization remained unknown. The discovery of glycogenin at the core of glycogen's structure and the initiation of its glucopolymerization is among one of the most exciting and relatively recent findings in Biochemistry. This review focuses on the initial steps leading to the seminal discoveries of proteoglycogen and glycogenin at the beginning of the 1980s, which paved the way for subsequent foundational breakthroughs that propelled forward this new research field. We also explore the current, as well as potential, impact this research field is having on human health and disease from the perspective of glycogen storage diseases. Important new questions arising from recent studies, their links to basic mechanisms involved in the de novo glycogen biogenesis, and the pervading presence of glycogenin across the evolutionary scale, fueled by high throughput -omics technologies, are also addressed.
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Wu L, Wong CP, Swanson RA. Methodological considerations for studies of brain glycogen. J Neurosci Res 2019; 97:914-922. [PMID: 30892752 DOI: 10.1002/jnr.24412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 01/02/2023]
Abstract
Glycogen stores in the brain have been recognized for decades, but the underlying physiological function of this energy reserve remains elusive. This uncertainty stems in part from several technical challenges inherent in the study of brain glycogen metabolism. These include low glycogen content in the brain, non-homogeneous labeling of glycogen by radiotracers, rapid glycogenolysis during postmortem tissue handling, and effects of the stress response on brain glycogen turnover. Here we briefly review the aspects of the glycogen structure and metabolism that bear on these technical challenges and present ways they can be addressed.
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Affiliation(s)
- Long Wu
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
| | - Candance P Wong
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
| | - Raymond A Swanson
- Department of Neurology, University of California, San Francisco, and San Francisco Veterans Affairs Health Care System, San Francisco, California
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Pancha I, Shima H, Higashitani N, Igarashi K, Higashitani A, Tanaka K, Imamura S. Target of rapamycin-signaling modulates starch accumulation via glycogenin phosphorylation status in the unicellular red alga Cyanidioschyzon merolae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:485-499. [PMID: 30351485 DOI: 10.1111/tpj.14136] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/23/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
The target of rapamycin (TOR) signaling pathway is involved in starch accumulation in various eukaryotic organisms; however, the molecular mechanism behind this phenomenon in eukaryotes has not been elucidated. We report a regulatory mechanism of starch accumulation by TOR in the unicellular red alga, Cyanidioschyzon merolae. The starch content in C. merolae after TOR-inactivation by rapamycin, a TOR-specific inhibitor, was increased by approximately 10-fold in comparison with its drug vehicle, dimethyl sulfoxide. However, our previous transcriptome analysis showed that the expression level of genes related to carbohydrate metabolism was unaffected by rapamycin, indicating that starch accumulation is regulated at post-transcriptional levels. In this study, we performed a phosphoproteome analysis using liquid chromatography-tandem mass spectrometry to investigate potential post-transcriptional modifications, and identified 52 proteins as candidate TOR substrates. Among the possible substrates, we focused on the function of CmGLG1, because its phosphorylation at the Ser613 residue was decreased after rapamycin treatment, and overexpression of CmGLG1 resulted in a 4.7-fold higher starch content. CmGLG1 is similar to the priming protein, glycogenin, which is required for the initiation of starch/glycogen synthesis, and a budding yeast complementation assay demonstrated that CmGLG1 can functionally substitute for glycogenin. We found an approximately 60% reduction in the starch content in a phospho-mimicking CmGLG1 overexpression strain, in which Ser613 was substituted with aspartic acid, in comparison with the wild-type CmGLG1 overexpression cells. Our results indicate that TOR modulates starch accumulation by changing the phosphorylation status of the CmGLG1 Ser613 residue in C. merolae.
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Affiliation(s)
- Imran Pancha
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Hiroki Shima
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Nahoko Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kazuhiko Igarashi
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Atsushi Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
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Brewer MK, Gentry MS. Brain Glycogen Structure and Its Associated Proteins: Past, Present and Future. ADVANCES IN NEUROBIOLOGY 2019; 23:17-81. [PMID: 31667805 PMCID: PMC7239500 DOI: 10.1007/978-3-030-27480-1_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This chapter reviews the history of glycogen-related research and discusses in detail the structure, regulation, chemical properties and subcellular distribution of glycogen and its associated proteins, with particular focus on these aspects in brain tissue.
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Affiliation(s)
- M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, Epilepsy and Brain Metabolism Center, Lafora Epilepsy Cure Initiative, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, USA.
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Wu L, Butler NJM, Swanson RA. Technical and Comparative Aspects of Brain Glycogen Metabolism. ADVANCES IN NEUROBIOLOGY 2019; 23:169-185. [DOI: 10.1007/978-3-030-27480-1_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Bezborodkina NN, Chestnova AY, Vorobev ML, Kudryavtsev BN. Spatial Structure of Glycogen Molecules in Cells. BIOCHEMISTRY (MOSCOW) 2018; 83:467-482. [PMID: 29738682 DOI: 10.1134/s0006297918050012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Glycogen is a strongly branched polymer of α-D-glucose, with glucose residues in the linear chains linked by 1→4-bonds (~93% of the total number of bonds) and with branching after every 4-8 residues formed by 1→6-glycosidic bonds (~7% of the total number of bonds). It is thought currently that a fully formed glycogen molecule (β-particle) with the self-glycosylating protein glycogenin in the center has a spherical shape with diameter of ~42 nm and contains ~ 55,000 glucose residues. The glycogen molecule also includes numerous proteins involved in its synthesis and degradation, as well as proteins performing a carcass function. However, the type and force of bonds connecting these proteins to the polysaccharide moiety of glycogen are significantly different. This review presents the available data on the spatial structure of the glycogen molecule and its changes under various physiological and pathological conditions.
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Affiliation(s)
- N N Bezborodkina
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia.
| | - A Yu Chestnova
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
| | - M L Vorobev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
| | - B N Kudryavtsev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
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Li B, Meng J, Li L, Liu S, Wang T, Zhang G. Identification and Functional Characterization of the Glycogen Synthesis Related Gene Glycogenin in Pacific Oysters (Crassostrea gigas). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:7764-7773. [PMID: 28780871 DOI: 10.1021/acs.jafc.7b02720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
High glycogen levels in the Pacific oyster (Crassostrea gigas) contribute to its flavor, quality, and hardiness. Glycogenin (CgGN) is the priming glucosyltransferase that initiates glycogen biosynthesis. We characterized the full sequence and function of C. gigas CgGN. Three CgGN isoforms (CgGN-α, β, and γ) containing alternative exon regions were isolated. CgGN expression varied seasonally in the adductor muscle and gonadal area and was the highest in the adductor muscle. Autoglycosylation of CgGN can interact with glycogen synthase (CgGS) to complete glycogen synthesis. Subcellular localization analysis showed that CgGN isoforms and CgGS were located in the cytoplasm. Additionally, a site-directed mutagenesis experiment revealed that the Tyr200Phe and Tyr202Phe mutations could affect CgGN autoglycosylation. This is the first study of glycogenin function in marine bivalves. These findings will improve our understanding of glycogen synthesis and accumulation mechanisms in mollusks. The data are potentially useful for breeding high-glycogen oysters.
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Affiliation(s)
- Busu Li
- University of Chinese Academy of Sciences , Beijing 100049, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, China
| | - Jie Meng
- Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, Shandong, China
| | - Li Li
- Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, Shandong, China
| | - Sheng Liu
- University of Chinese Academy of Sciences , Beijing 100049, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, China
| | - Ting Wang
- University of Chinese Academy of Sciences , Beijing 100049, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, China
| | - Guofan Zhang
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology , Qingdao 266000, China
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Krag TO, Ruiz-Ruiz C, Vissing J. Glycogen Synthesis in Glycogenin 1-Deficient Patients: A Role for Glycogenin 2 in Muscle. J Clin Endocrinol Metab 2017; 102:2690-2700. [PMID: 28453664 DOI: 10.1210/jc.2017-00399] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/21/2017] [Indexed: 02/13/2023]
Abstract
CONTEXT Glycogen storage disease (GSD) type XV is a rare disease caused by mutations in the GYG1 gene that codes for the core molecule of muscle glycogen, glycogenin 1. Nonetheless, glycogen is present in muscles of glycogenin 1-deficient patients, suggesting an alternative for glycogen buildup. A likely candidate is glycogenin 2, an isoform expressed in the liver and heart but not in healthy skeletal muscle. OBJECTIVE We wanted to investigate the formation of glycogen and changes in glycogen metabolism in patients with GSD type XV. DESIGN, SETTING, AND PATIENTS Two patients with mutations in the GYG1 gene were investigated for histopathology, ultrastructure, and expression of proteins involved in glycogen synthesis and metabolism. RESULTS Apart from occurrence of polyglucosan (PG) bodies in few fibers, glycogen appeared normal in most cells, and the concentration was normal in patients with GSD type XV. We found that glycogenin 1 was absent, but glycogenin 2 was present in the patients, whereas the opposite was the case in healthy controls. Electron microscopy revealed that glycogen was present between and not inside myofibrils in type II fibers, compromising the ultrastructure of these fibers, and only type I fibers contained PG bodies. We also found significant changes to the expression levels of several enzymes directly involved in glycogen and glucose metabolism. CONCLUSIONS To our knowledge, this is the first report demonstrating expression of glycogenin 2 in glycogenin 1-deficient patients, suggesting that glycogenin 2 rescues the formation of glycogen in patients with glycogenin 1 deficiency.
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Affiliation(s)
- Thomas O Krag
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Cristina Ruiz-Ruiz
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
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Testoni G, Duran J, García-Rocha M, Vilaplana F, Serrano AL, Sebastián D, López-Soldado I, Sullivan MA, Slebe F, Vilaseca M, Muñoz-Cánoves P, Guinovart JJ. Lack of Glycogenin Causes Glycogen Accumulation and Muscle Function Impairment. Cell Metab 2017; 26:256-266.e4. [PMID: 28683291 DOI: 10.1016/j.cmet.2017.06.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/08/2017] [Accepted: 06/13/2017] [Indexed: 11/27/2022]
Abstract
Glycogenin is considered essential for glycogen synthesis, as it acts as a primer for the initiation of the polysaccharide chain. Against expectations, glycogenin-deficient mice (Gyg KO) accumulate high amounts of glycogen in striated muscle. Furthermore, this glycogen contains no covalently bound protein, thereby demonstrating that a protein primer is not strictly necessary for the synthesis of the polysaccharide in vivo. Strikingly, in spite of the higher glycogen content, Gyg KO mice showed lower resting energy expenditure and less resistance than control animals when subjected to endurance exercise. These observations can be attributed to a switch of oxidative myofibers toward glycolytic metabolism. Mice overexpressing glycogen synthase in the muscle showed similar alterations, thus indicating that this switch is caused by the excess of glycogen. These results may explain the muscular defects of GSD XV patients, who lack glycogenin-1 and show high glycogen accumulation in muscle.
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Affiliation(s)
- Giorgia Testoni
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain
| | - Jordi Duran
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid 28029, Spain
| | - Mar García-Rocha
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain
| | - Francisco Vilaplana
- Division of Glycoscience, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm 10691, Sweden
| | - Antonio L Serrano
- Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), CIBER on Neurodegenerative diseases (CIBERNED), Barcelona 08003, Spain
| | - David Sebastián
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid 28029, Spain; Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona 08028, Spain
| | - Iliana López-Soldado
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid 28029, Spain
| | - Mitchell A Sullivan
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Felipe Slebe
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain
| | - Marta Vilaseca
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain
| | - Pura Muñoz-Cánoves
- Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), CIBER on Neurodegenerative diseases (CIBERNED), Barcelona 08003, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain; Spanish National Center on Cardiovascular Research (CNIC), Madrid 28029, Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid 28029, Spain; Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona 08028, Spain.
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Camiruaga A, Usabiaga I, Insausti A, Cocinero EJ, León I, Fernández JA. Understanding the role of tyrosine in glycogenin. MOLECULAR BIOSYSTEMS 2017; 13:1709-1712. [DOI: 10.1039/c7mb00293a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
α-/β-Glucose shows a particular affinity for the O3H and O4H moieties of β-PhGlc in the synthesis of glucogen.
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Affiliation(s)
- Ander Camiruaga
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
| | - Imanol Usabiaga
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
| | - Aran Insausti
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
| | - Emilio J. Cocinero
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
| | - Iker León
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
| | - José A. Fernández
- Dpto. de Química Física
- Facultad de Ciencia y Tecnología
- Universidad del País Vasco-UPV/EHU
- Leioa
- Spain
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LC-MS/MS characterization of combined glycogenin-1 and glycogenin-2 enzymatic activities reveals their self-glucosylation preferences. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1844:398-405. [PMID: 24239874 DOI: 10.1016/j.bbapap.2013.11.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/17/2013] [Accepted: 11/07/2013] [Indexed: 11/20/2022]
Abstract
Glycogen synthesis is initiated by self-glucosylation of the glycosyltransferases glycogenin-1 and -2 that, in the presence of UDP-glucose, form both the first glucose-O-tyrosine linkage, and then stepwise add a series of α1,4-linked glucoses to a growing chain of variable length. Glycogen-1 and -2 coexist in liver glycogen preparations where the proteins are known to form homodimers, and they also have been shown to interact with each other. In order to study how glycogenin-1 and -2 interactions may influence each other's glucosylations we setup a cell-free expression system for in vitro production and glucosylation of glycogenin-1 and -2 in various combinations, and used a mass spectrometry based workflow for the characterization and quantitation of tryptic glycopeptides originating from glycogenin-1 and -2. The analysis revealed that the self-glucosylation endpoint was the incorporation of 4-8 glucose units on Tyr 195 of glycogenin-1, but only 0-4 glucose units on Tyr-228 of glycogenin-2. The glucosylation of glycogenin-2 was enhanced to 2-4 glucose units by the co-presence of enzymatically active glycogenin-1. Glycogenin-2 was, however, unable to glucosylate inactive glycogenin-1, at least not an enzymatically inactivated Thr83Met glycogenin-1 mutant, recently identified in a patient with severe glycogen depletion.
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15
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A hemizygous GYG2 mutation and Leigh syndrome: a possible link? Hum Genet 2013; 133:225-34. [DOI: 10.1007/s00439-013-1372-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 09/29/2013] [Indexed: 11/26/2022]
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Nocturnin in the demosponge Suberites domuncula: a potential circadian clock protein controlling glycogenin synthesis in sponges. Biochem J 2013; 448:233-42. [PMID: 22928820 DOI: 10.1042/bj20120357] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sponges are filter feeders that consume a large amount of energy to allow a controlled filtration of water through their aquiferous canal systems. It has been shown that primmorphs, three-dimensional cell aggregates prepared from the demosponge Suberites domuncula and cultured in vitro, change their morphology depending on the light supply. Upon exposure to light, primmorphs show a faster and stronger increase in DNA, protein and glycogen content compared with primmorphs that remain in the dark. The sponge genome contains nocturnin, a light/dark-controlled clock gene, the protein of which shares a high sequence similarity with the related molecule of higher metazoans. The sponge nocturnin protein was found showing a poly(A)-specific 3'-exoribonuclease activity. In addition, the cDNA of the glycogenin gene was identified for subsequent expression studies. Antibodies against nocturnin were raised and used in parallel with the cDNA to determine the regional expression of nocturnin in intact sponge specimens; the highest expression of nocturnin was seen in the epithelial layer around the aquiferous canals. Quantitative PCR analyses revealed that primmorphs after transfer from light to dark show a 10-fold increased expression in the nocturnin gene. In contrast, the expression level of glycogenin decreases in the dark by 3-4-fold. Exposure of primmorphs to light causes a decrease in nocturnin transcripts and a concurrent increase in glycogenin transcripts. It was concluded that sponges are provided with the molecular circadian clock protein nocturnin that is highly expressed in the dark where it controls the stability of a key metabolic enzyme, glycogenin.
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Palm DC, Rohwer JM, Hofmeyr JHS. Regulation of glycogen synthase from mammalian skeletal muscle--a unifying view of allosteric and covalent regulation. FEBS J 2012; 280:2-27. [PMID: 23134486 DOI: 10.1111/febs.12059] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/29/2012] [Accepted: 11/05/2012] [Indexed: 12/27/2022]
Abstract
It is widely accepted that insufficient insulin-stimulated activation of muscle glycogen synthesis is one of the major components of non-insulin-dependent (type 2) diabetes mellitus. Glycogen synthase, a key enzyme in muscle glycogen synthesis, is extensively regulated, both allosterically (by glucose-6-phosphate, ATP, and others) and covalently (by phosphorylation). Although glycogen synthase has been a topic of intense study for more than 50 years, its kinetic characterization has been confounded by its large number of phosphorylation states. Questions remain regarding the function of glycogen synthase regulation and the relative importance of allosteric and covalent modification in fulfilling this function. In this review, we consider both earlier kinetic studies and more recent site-directed mutagenesis and crystal structure studies in a detailed qualitative discussion of the effects of regulation on the kinetics of glycogen synthase. We propose that both allosteric and covalent modification of glycogen synthase may be described by a Monod-Wyman-Changeux model in terms of apparent changes to L, the equilibrium constant for transition between the T and R conformers. As, with the exception of L, all parameters of this model are independent of the glycogen synthase phosphorylation state, the need to determine kinetic parameters for all possible states is eliminated; only the relationship between a particular state and L must be established. We conclude by suggesting that renewed efforts to characterize the relationship between phosphorylation and the kinetics of glycogen synthase are essential in order to obtain a better quantitative understanding of the function of glycogen synthesis regulation. The model we propose may prove useful in this regard.
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Affiliation(s)
- Daniel C Palm
- Triple J Group for Molecular Cell Physiology, Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
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Abstract
Glycogen is a branched polymer of glucose that acts as a store of energy in times of nutritional sufficiency for utilization in times of need. Its metabolism has been the subject of extensive investigation and much is known about its regulation by hormones such as insulin, glucagon and adrenaline (epinephrine). There has been debate over the relative importance of allosteric compared with covalent control of the key biosynthetic enzyme, glycogen synthase, as well as the relative importance of glucose entry into cells compared with glycogen synthase regulation in determining glycogen accumulation. Significant new developments in eukaryotic glycogen metabolism over the last decade or so include: (i) three-dimensional structures of the biosynthetic enzymes glycogenin and glycogen synthase, with associated implications for mechanism and control; (ii) analyses of several genetically engineered mice with altered glycogen metabolism that shed light on the mechanism of control; (iii) greater appreciation of the spatial aspects of glycogen metabolism, including more focus on the lysosomal degradation of glycogen; and (iv) glycogen phosphorylation and advances in the study of Lafora disease, which is emerging as a glycogen storage disease.
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Conformational plasticity of glycogenin and its maltosaccharide substrate during glycogen biogenesis. Proc Natl Acad Sci U S A 2011; 108:21028-33. [PMID: 22160680 DOI: 10.1073/pnas.1113921108] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glycogenin initiates the synthesis of a maltosaccharide chain covalently attached to itself on Tyr195 via a stepwise glucosylation reaction, priming glycogen synthesis. We have captured crystallographic snapshots of human glycogenin during its reaction cycle, revealing a dynamic conformational switch between ground and active states mediated by the sugar donor UDP-glucose. This switch includes the ordering of a polypeptide stretch containing Tyr195, and major movement of an approximately 30-residue "lid" segment covering the active site. The rearranged lid guides the nascent maltosaccharide chain into the active site in either an intra- or intersubunit mode dependent upon chain length and steric factors and positions the donor and acceptor sugar groups for catalysis. The Thr83Met mutation, which causes glycogen storage disease XV, is conformationally locked in the ground state and catalytically inactive. Our data highlight the conformational plasticity of glycogenin and coexistence of two modes of glucosylation as integral to its catalytic mechanism.
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Nilsson J, Halim A, Moslemi AR, Pedersen A, Nilsson J, Larson G, Oldfors A. Molecular pathogenesis of a new glycogenosis caused by a glycogenin-1 mutation. Biochim Biophys Acta Mol Basis Dis 2011; 1822:493-9. [PMID: 22198226 DOI: 10.1016/j.bbadis.2011.11.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 11/07/2011] [Accepted: 11/28/2011] [Indexed: 11/29/2022]
Abstract
Glycogenin-1 initiates the glycogen synthesis in skeletal muscle by the autocatalytic formation of a short oligosaccharide at tyrosine 195. Glycogenin-1 catalyzes both the glucose-O-tyrosine linkage and the α1,4 glucosidic bonds linking the glucose molecules in the oligosaccharide. We recently described a patient with glycogen depletion in skeletal muscle as a result of a non-functional glycogenin-1. The patient carried a Thr83Met substitution in glycogenin-1. In this study we have investigated the importance of threonine 83 for the catalytic activity of glycogenin-1. Non-glucosylated glycogenin-1 constructs, with various amino acid substitutions in position 83 and 195, were expressed in a cell-free expression system and autoglucosylated in vitro. The autoglucosylation was analyzed by gel-shift on western blot, incorporation of radiolabeled UDP-(14)C-glucose and nano-liquid chromatography with tandem mass spectrometry (LC/MS/MS). We demonstrate that glycogenin-1 with the Thr83Met substitution is unable to form the glucose-O-tyrosine linkage at tyrosine 195 unless co-expressed with the catalytically active Tyr195Phe glycogenin-1. Our results explain the glycogen depletion in the patient expressing only Thr83Met glycogenin-1 and why heterozygous carriers without clinical symptoms show a small proportion of unglucosylated glycogenin-1.
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Affiliation(s)
- Johanna Nilsson
- Department of Pathology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
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Kruszynska YT, Ciaraldi TP, Henry RR. Regulation of Glucose Metabolism in Skeletal Muscle. Compr Physiol 2011. [DOI: 10.1002/cphy.cp070218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Moslemi AR, Lindberg C, Nilsson J, Tajsharghi H, Andersson B, Oldfors A. Glycogenin-1 deficiency and inactivated priming of glycogen synthesis. N Engl J Med 2010; 362:1203-10. [PMID: 20357282 DOI: 10.1056/nejmoa0900661] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glycogen, which serves as a major energy reserve in cells, is a large, branched polymer of glucose molecules. We describe a patient who had muscle weakness, associated with the depletion of glycogen in skeletal muscle, and cardiac arrhythmia, associated with the accumulation of abnormal storage material in the heart. The skeletal muscle showed a marked predominance of slow-twitch, oxidative muscle fibers and mitochondrial proliferation. Western blotting showed the presence of unglucosylated glycogenin-1 in the muscle and heart. Sequencing of the glycogenin-1 gene, GYG1, revealed a nonsense mutation in one allele and a missense mutation, Thr83Met, in the other. The missense mutation resulted in inactivation of the autoglucosylation of glycogenin-1 that is necessary for the priming of glycogen synthesis in muscle.
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Affiliation(s)
- Ali-Reza Moslemi
- Department of Pathology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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Evidence for glycogenin autoglucosylation cessation by inaccessibility of the acquired maltosaccharide. Biochem Biophys Res Commun 2008; 374:704-8. [DOI: 10.1016/j.bbrc.2008.07.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 07/18/2008] [Indexed: 11/18/2022]
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Bazán S, Issoglio FM, Carrizo ME, Curtino JA. The intramolecular autoglucosylation of monomeric glycogenin. Biochem Biophys Res Commun 2008; 371:328-32. [DOI: 10.1016/j.bbrc.2008.04.076] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 04/16/2008] [Indexed: 11/28/2022]
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Hurley TD, Walls C, Bennett JR, Roach PJ, Wang M. Direct detection of glycogenin reaction products during glycogen initiation. Biochem Biophys Res Commun 2006; 348:374-8. [PMID: 16889748 PMCID: PMC1635985 DOI: 10.1016/j.bbrc.2006.07.106] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 07/07/2006] [Indexed: 10/24/2022]
Abstract
Glycogenin initiates glycogen synthesis in an autocatalytic reaction in which individual glucose residues are covalently linked to Tyrosine 194 in order to form a short priming chain of glucose residues that is a substrate for glycogen synthase which, combined with the branching enzyme, catalyzes the bulk synthesis of glycogen. We sought to develop a new enzymatic assay to better characterize both the chemical and enzymatic characteristics of this unusual reaction. By directly detecting the reaction products using electrospray mass spectrometry this procedure permits both the visualization of the intact individual reaction species produced as a function of time and quantitation of the levels of each of species. The quantitation of the reaction agrees well with previous measurements of both catalytic rate and the change in rate as a function of average glucosylation. The results from this assay provide new insight into the mechanism by which glycogenin catalyzes the initiation reaction.
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Affiliation(s)
- Thomas D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
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Shearer J, Graham TE, Battram DS, Robinson DL, Richter EA, Wilson RJ, Bakovic M. Glycogenin activity and mRNA expression in response to volitional exhaustion in human skeletal muscle. J Appl Physiol (1985) 2005; 99:957-62. [PMID: 15860684 DOI: 10.1152/japplphysiol.00275.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glycogenolysis results in the selective catabolism of individual glycogen granules by glycogen phosphorylase. However, once the carbohydrate portion of the granule is metabolized, the fate of glycogenin, the protein primer of granule formation, is not known. To examine this, male subjects ( n = 6) exercised to volitional exhaustion (Exh) on a cycle ergometer at 75% maximal O2uptake. Muscle biopsies were obtained at rest, 30 min, and Exh (99 ± 10 min). At rest, total glycogen concentration was 497 ± 41 and declined to 378 ± 51 mmol glucosyl units/kg dry wt following 30 min of exercise ( P < 0.05). There were no significant changes in proglycogen, macroglycogen, glycogenin activity, or mRNA in this period ( P ≥ 0.05). Exh resulted in decreases in total glycogen, proglycogen, and macroglycogen as well as glycogenin activity ( P < 0.05). These decrements were associated with a 1.9 ± 0.4-fold increase in glycogenin mRNA over resting values ( P < 0.05). Glycogenolysis in the initial exercise period (0–30 min) was not adequate to induce changes in glycogenin; however, later in exercise when concentration and granule number decreased further, decrements in glycogenin activity and increases in glycogenin mRNA were demonstrated. Results show that glycogenin becomes inactivated with glycogen catabolism and that this event coincides with an increase in glycogenin gene expression as exercise and glycogenolysis progress.
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Affiliation(s)
- Jane Shearer
- Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada.
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Hurley TD, Stout S, Miner E, Zhou J, Roach PJ. Requirements for catalysis in mammalian glycogenin. J Biol Chem 2005; 280:23892-9. [PMID: 15849187 PMCID: PMC1266300 DOI: 10.1074/jbc.m502344200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogenin is a glycosyltransferase that functions as the autocatalytic initiator for the synthesis of glycogen in eukaryotic organisms. Prior structural work identified the determinants responsible for the recognition and binding of UDP-glucose and the catalytic manganese ion and implicated two aspartic acid residues in the reaction mechanism for self-glucosylation. We examined the effects of substituting asparagine and serine for the aspartic acid residues at positions 159 and 162. We also examined whether the truncation of the protein at residue 270 (delta270) was compatible with its structural integrity and its functional role as the initiator for glycogen synthesis. The truncated form of the enzyme was indistinguishable from the wild-type enzyme by all measures of activity and could support glycogen accumulation in a glycogenin-deficient yeast strain. Substitution of aspartate 159 by either serine or asparagine eliminated self-glucosylation and reduced trans-glucosylation activity by at least 260-fold but only reduced UDP-glucose hydrolytic activity by 4-14-fold. Substitution of aspartate 162 by either serine or asparagine eliminated self-glucosylation activity and reduced UDP-glucose hydrolytic activity by at least 190-fold. The trans-glucosylation of maltose was reduced to undetectable levels in the asparagine 162 mutant, whereas the serine 162 enzyme showed only an 18-30-fold reduction in its ability to trans-glucosylate maltose. These data support a role for aspartate 162 in the chemical step for the glucosyltransferase reaction and a role for aspartate 159 in binding and activating the acceptor molecule.
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Affiliation(s)
- Thomas D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA.
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29
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de Paula RM, Wilson WA, Roach PJ, Terenzi HF, Bertolini MC. Biochemical characterization of Neurospora crassa glycogenin (GNN), the self-glucosylating initiator of glycogen synthesis. FEBS Lett 2005; 579:2208-14. [PMID: 15811343 DOI: 10.1016/j.febslet.2005.02.075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Revised: 02/01/2005] [Accepted: 02/21/2005] [Indexed: 11/27/2022]
Abstract
Glycogenin acts in the initiation step of glycogen biosynthesis by catalyzing a self-glucosylation reaction. In a previous work [de Paula et al., Arch. Biochem. Biophys. 435 (2005) 112-124], we described the isolation of the cDNA gnn, which encodes the protein glycogenin (GNN) in Neurospora crassa. This work presents a set of biochemical and functional studies confirming the GNN role in glycogen biosynthesis. Kinetic experiments showed a very low GNN K(m) (4.41 microM) for the substrate UDP-glucose. Recombinant GNN was produced in Escherichia coli and analysis by mass spectroscopy identified a peptide containing an oligosaccharide chain attached to Tyr196 residue. Site-directed mutagenesis and functional complementation of a Saccharomyces cerevisiae mutant strain confirmed the participation of this residue in the GNN self-glucosylation and indicated the Tyr198 residue as an additional, although less active, glucosylation site. The physical interaction between GNN and glycogen synthase (GSN) was analyzed by the two-hybrid assay. While the entire GSN was required for full interaction, the C-terminus in GNN was more important. Furthermore, mutation in the GNN glucosylation sites did not impair the interaction with GSN.
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Affiliation(s)
- Renato M de Paula
- Instituto de Química, UNESP, Departamento de Bioquímica e Tecnologia Química, R. Professor Francisco Degni, s/n, 14800-900 Araraquara, SP, Brazil
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30
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de Paula RM, Wilson WA, Terenzi HF, Roach PJ, Bertolini MC. GNN is a self-glucosylating protein involved in the initiation step of glycogen biosynthesis in Neurospora crassa. Arch Biochem Biophys 2005; 435:112-24. [PMID: 15680913 DOI: 10.1016/j.abb.2004.12.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 12/02/2004] [Indexed: 10/26/2022]
Abstract
The initiation of glycogen synthesis requires the protein glycogenin, which incorporates glucose residues through a self-glucosylation reaction, and then acts as substrate for chain elongation by glycogen synthase and branching enzyme. Numerous sequences of glycogenin-like proteins are available in the databases but the enzymes from mammalian skeletal muscle and from Saccharomyces cerevisiae are the best characterized. We report the isolation of a cDNA from the fungus Neurospora crassa, which encodes a protein, GNN, which has properties characteristic of glycogenin. The protein is one of the largest glycogenins but shares several conserved domains common to other family members. Recombinant GNN produced in Escherichia coli was able to incorporate glucose in a self-glucosylation reaction, to trans-glucosylate exogenous substrates, and to act as substrate for chain elongation by glycogen synthase. Recombinant protein was sensitive to C-terminal proteolysis, leading to stable species of around 31kDa, which maintained all functional properties. The role of GNN as an initiator of glycogen metabolism was confirmed by its ability to complement the glycogen deficiency of a S. cerevisiae strain (glg1 glg2) lacking glycogenin and unable to accumulate glycogen. Disruption of the gnn gene of N. crassa by repeat induced point mutation (RIP) resulted in a strain that was unable to synthesize glycogen, even though the glycogen synthase activity was unchanged. Northern blot analysis showed that the gnn gene was induced during vegetative growth and was repressed upon carbon starvation.
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Affiliation(s)
- Renato Magalhães de Paula
- Instituto de Química, UNESP, Departamento de Bioquímica e Tecnologia Química, 14800-900 Araraquara, SP, Brazil
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Albrecht T, Haebel S, Koch A, Krause U, Eckermann N, Steup M. Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosine residues but results in a reduced bacterial glycogen accumulation. ACTA ACUST UNITED AC 2005; 271:3978-89. [PMID: 15479227 DOI: 10.1111/j.1432-1033.2004.04333.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His6) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis.
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Affiliation(s)
- Tanja Albrecht
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
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Romero JM, Curtino JA. C-chain-bound glycogenin is released from proteoglycogen by isoamylase and is able to autoglucosylate. Biochem Biophys Res Commun 2003; 305:811-4. [PMID: 12767902 DOI: 10.1016/s0006-291x(03)00861-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Proteoglycogen glycogenin is linked to the glucose residue of the C-chain reducing end of glycogen. We describe for the first time the release by isoamylase and isolation of C-chain-bound glycogenin (C-glycogenin) from proteoglycogen. The treatment of proteoglycogen with alpha-amylase releases monoglucosylated and diglucosylated glycogenin (a-glycogenin) which is able to autoglucosylate. It had been described that isoamylase splits the glucose-glycogenin linkage of fully autoglucosylated glycogenin previously digested with trypsin, releasing the maltosaccharide moiety. It was also described that carbohydrate-free apo-glycogenin shows higher mobility in SDS-PAGE and twice the autoglucosylation capacity of partly glucosylated glycogenin. On the contrary, we found that the C-glycogenin released from proteoglycogen by isoamylolysis shows lower mobility in SDS-PAGE and about half the autoglucosylation acceptor capacity of the partly glucosylated a-glycogenin. This behavior is consistent with the release of maltosaccharide-bound glycogenin instead of apo-glycogenin. No label was split from auto-[14C]glucosylated C-glycogenin or fully auto-[14C]glucosylated a-glycogenin subjected to isoamylolysis without previous trypsinolysis, thus proving no hydrolysis of the maltosaccharide-tyrosine linkage. The ability of C-glycogenin for autoglucosylation would indicate that the size of the C-chain is lower than the average length of the other glycogen chains.
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Affiliation(s)
- Jorge M Romero
- Centro de Investigaciones en Química Biológica de Córdoba, UNC-CONICET, Departamento de Química Biológica Dr. Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 500 Córdoba, Argentina
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Gibbons BJ, Roach PJ, Hurley TD. Crystal structure of the autocatalytic initiator of glycogen biosynthesis, glycogenin. J Mol Biol 2002; 319:463-77. [PMID: 12051921 DOI: 10.1016/s0022-2836(02)00305-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Glycogen is an important storage reserve of glucose present in many organisms, from bacteria to humans. Its biosynthesis is initiated by a specialized protein, glycogenin, which has the unusual property of transferring glucose from UDP-glucose to form an oligosaccharide covalently attached to itself at Tyr194. Glycogen synthase and the branching enzyme complete the synthesis of the polysaccharide. The structure of glycogenin was solved in two different crystal forms. Tetragonal crystals contained a pentamer of dimers in the asymmetric unit arranged in an improper non-crystallographic 10-fold relationship, and orthorhombic crystals contained a monomer in the asymmetric unit that is arranged about a 2-fold crystallographic axis to form a dimer. The structure was first solved to 3.4 A using the tetragonal crystal form and a three-wavelength Se-Met multi-wavelength anomalous diffraction (MAD) experiment. Subsequently, an apo-enzyme structure and a complex between glycogenin and UDP-glucose/Mn2+ were solved by molecular replacement to 1.9 A using the orthorhombic crystal form. Glycogenin contains a conserved DxD motif and an N-terminal beta-alpha-beta Rossmann-like fold that are common to the nucleotide-binding domains of most glycosyltransferases. Although sequence identity amongst glycosyltransferases is minimal, the overall folds are similar. In all of these enzymes, the DxD motif is essential for coordination of the catalytic divalent cation, most commonly Mn2+. We propose a mechanism in which the Mn2+ that associates with the UDP-glucose molecule functions as a Lewis acid to stabilize the leaving group UDP and to facilitate the transfer of the glucose moiety to an intermediate nucleophilic acceptor in the enzyme active site, most likely Asp162. Following transient transfer to Asp162, the glucose moiety is then delivered to the final acceptor, either directly to Tyr194 or to glucose residues already attached to Tyr194. The positioning of the bound UDP-glucose far from Tyr194 in the glycogenin structure raises questions as to the mechanism for the attachment of the first glucose residues. Possibly the initial glucosylation is via inter-dimeric catalysis with an intra-molecular mechanism employed later in oligosaccharide synthesis.
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Affiliation(s)
- Brian J Gibbons
- Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, 635 Barnhill Drive Indianapolis, IN 46202-5122, USA
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Skurat AV, Dietrich AD, Zhai L, Roach PJ. GNIP, a novel protein that binds and activates glycogenin, the self-glucosylating initiator of glycogen biosynthesis. J Biol Chem 2002; 277:19331-8. [PMID: 11916970 DOI: 10.1074/jbc.m201190200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogenin is a self-glucosylating protein involved in the initiation of glycogen biosynthesis. Self-glucosylation leads to the formation of an oligosaccharide chain, which, when long enough, supports the action of glycogen synthase to elongate it and form a mature glycogen molecule. To identify possible regulators of glycogenin, the yeast two-hybrid strategy was employed. By using rabbit skeletal muscle glycogenin as a bait, cDNAs encoding three different proteins were isolated from the human skeletal muscle cDNA library. Two of the cDNAs encoded glycogenin and glycogen synthase, respectively, proteins known to be interactors. The third cDNA encoded a polypeptide of unknown function and was designated GNIP (glycogenin interacting protein). Northern blot analysis revealed that GNIP mRNA is highly expressed in skeletal muscle. The gene for GNIP generates at least four isoforms by alternative splicing. The largest isoform GNIP1 contains, from NH(2)- to COOH-terminal, a RING finger, a B box, a putative coiled-coil region, and a B30.2-like motif. The previously identified protein TRIM7 (tripartite motif containing protein 7) is also derived from the GNIP gene and is composed of the RING finger, B box, and coiled-coil regions. The GNIP2 and GNIP3 isoforms consist of the coiled-coil region and B30.2-like domain. Physical interaction between GNIP2 and glycogenin was confirmed by co-immunoprecipitation, and in addition GNIP2 was shown to stimulate glycogenin self-glucosylation 3-4-fold. GNIPs may represent a novel participant in the initiation of glycogen synthesis.
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Affiliation(s)
- Alexander V Skurat
- Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Tolmasky DS, Rabossi A, Quesada-Allué LA. Synthesis and mobilization of glycogen during metamorphosis of the medfly Ceratitis capitata. Arch Biochem Biophys 2001; 392:38-47. [PMID: 11469792 DOI: 10.1006/abbi.2001.2394] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There are no recent reports focusing on insect glycogen metabolism that take the advances made in mammalian and yeast systems into account. Moreover, little is known about glycogen synthesis and degradation during insect metamorphosis. The biosynthesis and mobilization of insect glycogen were measured during the larva to adult transition in the Medfly, Ceratitis capitata. The glycogen accumulated by larva decreased to reach almost undetectable levels at the beginning of the pupation process. Histological preparations of 40 h muscles and fat body confirmed a low glycogen content, in contrast with high glycogen images in third larva tissues. After 40 h, glycogen was synthesized de novo and accumulates up to adult ecdysis. We obtained the metamorphosis-dependent profiles of phosphorylase, glycogen synthase, and a glycogenin-like protein. This novel insect glycogen initiator protein (the first measured in an arthropod) appeared to be similar to the homologous enzymes from vertebrates and yeast. We have correlated these results with other biochemical events and anatomical landmarks to understand the use of storage carbohydrates during the sequence of metamorphosis events.
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Affiliation(s)
- D S Tolmasky
- Instituto de Investigaciones Bioquiimicas, Fundación Campomar, CONICET and University of Buenos Aires, Avenue Patricias Argentinas 435, Buenos Aires (1405), Argentina
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36
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Abstract
In Ascaris suum, muscle glycogen is synthesized during host feeding intervals and degraded during nonfeeding intervals. Glycogen accumulation is up to 12-fold greater than that observed in mammalian muscle. Previous studies have established that many aspects of the parasite glycogen metabolism are comparable with the host, but a novel form of glycogen synthase designated GSII also occurs in the parasite. In this report glycogenin has been identified as the core protein in both mature glycogen and the GSII complex. Digestion of GSII complex glycogen generates discreet intermediates that may correspond to a proglycogen pool, whereas digestion of mature glycogen does not generate these intermediates. Because both GSII complex glycogen and mature glycogen serve as GSII substrates, the GSII complex likely represents an intermediate between glycogenin and mature glycogen. The regulation of glycogenin synthesis or the regulation of GSII activity that converts glycogenin to proglycogen, or both, may account for high levels of polysaccharide accumulation that are essential for A. suum survival.
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Affiliation(s)
- R A Masaracchia
- Department of Biological Sciences. University of North Texas, Denton 76203, USA
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37
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Roach PJ, Cheng C, Huang D, Lin A, Mu J, Skurat AV, Wilson W, Zhai L. Novel aspects of the regulation of glycogen storage. J Basic Clin Physiol Pharmacol 1999; 9:139-51. [PMID: 10212831 DOI: 10.1515/jbcpp.1998.9.2-4.139] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The storage polysaccharide glycogen is widely distributed in nature, from bacteria to mammals. Study of its regulated accumulation has resulted in the discovery or elaboration of several important biochemical principles. Many aspects of the control of glycogen storage still remain poorly understood and glycogen metabolism continues to provide interesting models of more general relevance.
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Affiliation(s)
- P J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, USA
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38
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Jiao Y, Shashkina E, Shashkin P, Hansson A, Katz A. Manganese sulfate-dependent glycosylation of endogenous glycoproteins in human skeletal muscle is catalyzed by a nonglucose 6-P-dependent glycogen synthase and not glycogenin. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1427:1-12. [PMID: 10082982 DOI: 10.1016/s0304-4165(98)00142-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Glycogenin, a Mn2+-dependent, self-glucosylating protein, is considered to catalyze the initial glucosyl transfer steps in glycogen biogenesis. To study the physiologic significance of this enzyme, measurements of glycogenin mediated glucose transfer to endogenous trichloroacetic acid precipitable material (protein-bound glycogen, i.e., glycoproteins) in human skeletal muscle were attempted. Although glycogenin protein was detected in muscle extracts, activity was not, even after exercise that resulted in marked glycogen depletion. Instead, a MnSO4-dependent glucose transfer to glycoproteins, inhibited by glycogen and UDP-pyridoxal (which do not affect glycogenin), and unaffected by CDP (a potent inhibitor of glycogenin), was consistently detected. MnSO4-dependent activity increased in concert with glycogen synthase fractional activity after prolonged exercise, and the MnSO4-dependent enzyme stimulated glucosylation of glycoproteins with molecular masses lower than those glucosylated by glucose 6-P-dependent glycogen synthase. Addition of purified glucose 6-P-dependent glycogen synthase to the muscle extract did not affect MnSO4-dependent glucose transfer, whereas glycogen synthase antibody completely abolished MnSO4-dependent activity. It is concluded that: (1) MnSO4-dependent glucose transfer to glycoproteins is catalyzed by a nonglucose 6-P-dependent form of glycogen synthase; (2) MnSO4-dependent glycogen synthase has a greater affinity for low molecular mass glycoproteins and may thus play a more important role than glucose 6-P-dependent glycogen synthase in the initial stages of glycogen biogenesis; and (3) glycogenin is generally inactive in human muscle in vivo.
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Affiliation(s)
- Y Jiao
- Department of Surgical Sciences, Division of Clinical Physiology, Karolinska Institute, Karolinska Hospital, 171 76, Stockholm, Sweden
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39
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Lin A, Mu J, Yang J, Roach PJ. Self-glucosylation of glycogenin, the initiator of glycogen biosynthesis, involves an inter-subunit reaction. Arch Biochem Biophys 1999; 363:163-70. [PMID: 10049511 DOI: 10.1006/abbi.1998.1073] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glycogenin is a dimeric self-glucosylating protein involved in the initiation phase of glycogen biosynthesis. As an enzyme, glycogenin has the unusual property of transferring glucose residues from UDP-glucose to itself, forming an alpha-1,4-glycan of around 10 residues attached to Tyr194. Whether this self-glucosylation reaction is inter- or intramolecular has been debated. We used site-directed mutagenesis of recombinant rabbit muscle glycogenin-1 to address this question. Mutation of highly conserved Lys85 to Gln generated a glycogenin mutant (K85Q) that had only 1-2% of the self-glucosylating activity of wild-type enzyme. Consistent with previous work, mutation of Tyr194 to Phe in a GST-fusion protein yielded a mutant, Y194F, that was catalytically active but incapable of self-glucosylation. The Y194F mutant was able to glucosylate the K85Q mutant. However, there was an initial lag in the self-glucosylation reaction that was abolished by preincubation of the two mutant proteins. The interaction between glycogenin subunits was relatively weak, with a dissociation constant inferred from kinetic experiments of around 2 microM. We propose a model for the glucosylation of K85Q by Y194F in which mixing of the proteins is followed by rate-limiting formation of a species containing both subunit types. The results provide the most direct evidence to date that the self-glucosylation of glycogenin involves an inter-subunit reaction.
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Affiliation(s)
- A Lin
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA
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40
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Mu J, Roach PJ. Characterization of human glycogenin-2, a self-glucosylating initiator of liver glycogen metabolism. J Biol Chem 1998; 273:34850-6. [PMID: 9857012 DOI: 10.1074/jbc.273.52.34850] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogenin-2 is a recently described self-glucosylating protein potentially involved in the initiation of glycogen biosynthesis (Mu, J., Skurat, A. V., and Roach, P. J. (1997) J. Biol. Chem. 272, 27589-27597). In human liver extracts, most of the glycogenin-2 was only detectable after treatment with alpha-amylase. Similarly, purifed high Mr glycogen was only detected after release by alpha-amylase treatment. Based on analysis by polymerase chain reaction, the predominant isoform in liver was glycogenin-2beta. Glycogenin-2 was found in Ewing's sarcoma RD-ES cells where, however, it was not associated with high Mr carbohydrate. Both human liver and human RD-ES cell extracts also contained glycogenin-1. Glycogenin-1 and glycogenin-2 interact with one another, based on in vitro interactions and co-immunoprecipitation from liver and cell extracts. Mutation of Tyr-196 in glycogenin-2 to a Phe residue abolished the ability of glycogenin-2 to self-glucosylate but not to interact with glycogenin-1. Stable overexpression of glycogenin-2alpha in Rat-1 fibroblast cells resulted in a 5-fold increase in the level of glycogen present in the low speed pellet but little change in the low speed supernatant. This result is important since it indicates that the level of glycogenin-2 can determine glycogen accumulation and hence has the potential to control glycogen synthesis.
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Affiliation(s)
- J Mu
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA
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41
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Baio DL, Czyz CN, Van Horn CG, Ivester P, Cunningham CC. Effect of chronic ethanol consumption on respiratory and glycolytic activities of rat periportal and perivenous hepatocytes. Arch Biochem Biophys 1998; 350:193-200. [PMID: 9473292 DOI: 10.1006/abbi.1997.0514] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Previous studies (Ivester et al., Arch. Biochem. Biophys. 322, 14-21, 1995) have established that periportal and perivenous hepatocytes isolated from ethanol-fed rats demonstrate lower ATP concentrations than those in control preparations when the cells are maintained at very low oxygen tension. In the present investigation, experiments were implemented with periportal and perivenous hepatocytes to determine the effects of chronic ethanol consumption on cellular respiratory and glycolytic activities, since both contribute to maintenance of the energy state of the liver cell. Both periportal and perivenous hepatocytes from ethanol-fed rats demonstrated significantly increased, rather than decreased, respiratory activity when monitored with oxygen concentrations ranging from 16 to 140 microM. Whole liver hepatocytes from control and ethanol-fed animals demonstrated equivalent oxygen utilization, however. Glycolytic activity, monitored by lactate + pyruvate concentrations obtained after both anaerobic and aerobic incubation protocols, was decreased in both cell types from ethanol-fed animals. The glycogen concentrations in freshly isolated periportal and perivenous hepatocytes were also decreased eight- and sevenfold, respectively, as compared with control preparations. Incubation under anaerobic conditions resulted in almost complete depletion of glycogen in both cell types. These observations suggest the possibility that the decreased energy state observed in hepatocytes from ethanol-fed animals is related to a depression in anaerobic glycolysis due to depletion of the endogenous substrate, glycogen.
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Affiliation(s)
- D L Baio
- Department of Biochemistry, Wake Forest University Medical Center, Winston-Salem, North Carolina 27157-1016, USA
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42
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Mu J, Skurat AV, Roach PJ. Glycogenin-2, a novel self-glucosylating protein involved in liver glycogen biosynthesis. J Biol Chem 1997; 272:27589-97. [PMID: 9346895 DOI: 10.1074/jbc.272.44.27589] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Glycogenin is a self-glucosylating protein involved in the initiation phase of glycogen biosynthesis. A single mammalian gene had been reported to account for glycogen biogenesis in liver and muscle, the two major repositories of glycogen. We describe the characterization of novel forms of glycogenin, designated glycogenin-2 (GN-2), encoded by a second gene that is expressed preferentially in certain tissues, including liver, heart, and pancreas. Cloning of cDNAs encoding glycogenin-2 indicated the existence of multiple species, including three liver forms (GN-2alpha, GN-2beta, and GN-2gamma) generated in part by alternative splicing. Overall, GN-2 has 40-45% identity to muscle glycogenin but is 72% identical over a 200-residue segment thought to contain the catalytic domain. GN-2 expressed in Escherichia coli or COS cells is active in self-glucosylation assays, and self-glucosylated GN-2 can be elongated by skeletal muscle glycogen synthase. Antibodies raised against GN-2 produced in E. coli recognized proteins of Mr approximately 66,000 present in extracts of rat liver and in cultured H4IIEC3 hepatoma cells. In H4IIEC3 cells, most of the GN-2 was present as a free protein but some was covalently associated with glycogen fractions and was only released by treatment with alpha-amylase. H4IIEC3 cells also expressed the muscle form of glycogenin (glycogenin-1), which was attached to a chromatographically separable glycogen fraction.
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Affiliation(s)
- J Mu
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA
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43
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Mu J, Cheng C, Roach PJ. Initiation of glycogen synthesis in yeast. Requirement of multiple tyrosine residues for function of the self-glucosylating Glg proteins in vivo. J Biol Chem 1996; 271:26554-60. [PMID: 8900126 DOI: 10.1074/jbc.271.43.26554] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The self-glucosylating proteins, Glg1p and Glg2p, are required for glycogen synthesis in Saccharomyces cerevisiae (Cheng, C., Mu., J., Farkas, I., Huang, D., Goebl M. G., and Roach, P. J. (1995) Mol. Cell. Biol. 15, 6632-6640). Glg2p was shown to be associated with carbohydrate in vivo and was released from the high molecular weight glycogen fraction by treatment with alpha-amylase. In addition, some Glg2p exists as a protein of Mr approximately 43,000, whose proportion is increased in cells lacking glycogen synthase. Unlike the mammalian counterpart, glycogenin, the yeast Glg proteins appear to require multiple Tyr residues for functionality. In Glg2p, mutation of both Tyr230 and Tyr232 is necessary to suppress self-glucosylation of purified protein in vitro. The mutant protein is still capable of transferring glucose to an exogeneous acceptor, n-dodecyl beta-D-maltoside. A small COOH-terminal region, conserved between Glg1p and Glg2p, is also important for function; mutation of Tyr367 or truncation at residue 362 impairs the ability of primed Glg2p to be elongated by glycogen synthase. Complete suppression of glycogen accumulation in vivo requires mutation of all three Tyr residues. In Glg1p, two Tyr residues are implicated, Tyr232 and Tyr600, mutation of both being required to eliminate glycogen accumulation in vivo.
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Affiliation(s)
- J Mu
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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44
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Affiliation(s)
- B G Winchester
- Division of Biochemistry and Genetics, Institute of Child Health, London, United Kingdom
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45
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Lomako J, Lomako WM, Whelan WJ. Glycogen metabolism in quail embryo muscle. The role of the glycogenin primer and the intermediate proglycogen. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 234:343-9. [PMID: 8529663 DOI: 10.1111/j.1432-1033.1995.343_c.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cultured quail embryo muscle has proven to be an excellent model system for studying the synthesis of macromolecular glycogen from, and its degradation to, glycogenin, the autocatalytic, self-glucosylating primer for glycogen synthesis. We recently demonstrated that proglycogen, a low-M(r) form of glycogen, is an intermediate in the synthesis. Here we show that proglycogen also functions as an intermediate in macroglycogen degradation and, in one set of circumstances, represents an arrest point in glycogen breakdown, which does not continue to glycogenin. We suggest that in the nutritionally dependent turnover of glycogen in tissues, the molecules cycle between proglycogen and macromolecular glycogen and are not normally degraded to glycogenin. Nevertheless, when this does happen, the released glycogenin is active, capable of re-initiating glycogen synthesis. Under culture conditions where the conversion of proglycogen into glycogenin does take place, the intermediates lying between form a discrete rather than a continuous series, suggestive of a cluster structure for proglycogen and indicating that breakdown is stepwise. Evidence of post-translational modification of glycogenin was obtained by the finding that, in glycogen from cultured muscle, glycogenin is phosphorylated.
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Affiliation(s)
- J Lomako
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, FL 33101, USA
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46
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Manzella S, Ananth S, Oegema TR, Rodén L, Rosenberg LC, Meezan E. Inhibition of glycogenin-catalyzed glucosyl and xylosyl transfer by cytidine 5'-diphosphate and related compounds. Arch Biochem Biophys 1995; 320:361-8. [PMID: 7625844 DOI: 10.1016/0003-9861(95)90020-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The self-glucosylation of beef kidney glycogenin was inhibited by the following pyrimidine nucleotides and nucleotide sugars, listed in order of decreasing effectiveness: CDP-glucose, CDP, UDP-xylose, UDP-N-acetylglucosamine, UDP-galactose, UDP, CTP, CDP-choline, UDP-glucuronic acid, beta-S-UDP-glucose, and CMP. In contrast, the purine nucleotide sugars, ADP-glucose and GDP-glucose, were essentially ineffective, as was the pyrimidine nucleoside, cytidine. UDP-Xylose may be utilized by glycogenin as an alternative sugar donor instead of UDP-glucose (Rodén, L., Ananth, S., Campbell, P., Manzella, S., and Meezan, E. (1994) J. Biol. Chem. 269, 11509-11513) and therefore presumably inhibited the glucosyl transfer reaction by being a competitive substrate. Like glucosyl transfer, xylosyl incorporation into glycogenin was also inhibited effectively by CDP. On the other hand, UDP-xylose:proteoglycan core protein xylosyltransferase (EC 2.4.2.26) was not affected by CDP, nor was it inhibited by UDP-glucose. Addition of CDP or UDP-glucose to reaction mixtures containing both enzymes therefore made it possible to assay xylosyltransferase EC 2.4.2.26 reliably without the extensive product characterization that is otherwise necessary. The CDP effect on glycogenin further allowed the development of an improved procedure for the purification of this enzyme, in which specific elution of an affinity matrix (UDP-glucuronic acid-agarose) was carried out with CDP as the eluant.
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Affiliation(s)
- S Manzella
- Department of Pharmacology, School of Medicine, University of Alabama at Birmingham 35294, USA
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47
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Alonso MD, Lomako J, Lomako WM, Whelan WJ. Catalytic activities of glycogenin additional to autocatalytic self-glucosylation. J Biol Chem 1995; 270:15315-9. [PMID: 7797519 DOI: 10.1074/jbc.270.25.15315] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Glycogenin is the autocatalytic, self-glucosylating protein that initiates glycogen synthesis in muscle and other tissues. We have sequenced the cDNA for rabbit muscle glycogenin and expressed and purified the protein in high yield as well as two mutant proteins in which Phe or Thr replaces Tyr-194, the site of glucosylation. While the wild-type protein can self-glucosylate, the mutants cannot, but all three utilize alternative acceptors by intermolecular glucose transfer for which the mutants have altered specificity. Tyr-194 is therefore not essential for the catalytic activity of glycogenin. All three proteins also hydrolyze UDP-glucose to glucose at rates comparable with the rate of self-glucosylation. The hydrolysis is competitive with glucose transfer to p-nitrophenyl alpha-maltoside. Self-glucosylation, glucosylation of other acceptors, and hydrolysis all appear to be catalyzed by the same active center. In the absence of peptidase inhibitors, the homogenous recombinant proteins of M(r) 37,000 break down to equally active species having M(r) 32,000. The kinetics of self-glucosylation catalyzed by the wild-type enzyme suggest that the reaction could be intermolecular rather than, as previously reported, intramolecular. The wild-type recombinant enzyme and native muscle glycogenin, which is phosphorylated, are inhibited quite differently by ATP at physiological concentration.
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Affiliation(s)
- M D Alonso
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Florida 33101, USA
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48
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Alonso MD, Lagzdins EJ, Lomako J, Lomako WM, Whelan WJ. New and specific nucleoside diphosphate glucose substrates for glycogenin. FEBS Lett 1995; 359:110-12. [PMID: 7867779 DOI: 10.1016/0014-5793(95)00018-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Glycogenin, the autocatalytic, self-glucosylating primer for glycogen synthesis by glycogen synthase, is presumed, in vivo, to use UDP-glucose as the source of the glucose residues it adds to itself. When we tested its ability to utilize other nucleoside diphosphate glucoses, it emerged that purine nucleotides are not utilized but two pyrimidine nucleotides are used, in addition to UDP-glucose. These are CDP-glucose and TDP-glucose. CDP-glucose is utilized at 70% of the rate of UDP-glucose. While there is no evidence that CDP-glucose is a natural substrate for glycogenin, it has the advantage over UDP-glucose in that it can be used specifically to detect and assay glycogenin in the presence of glycogen synthase because CDP-glucose, unlike UDP-glucose, is not a substrate for the synthase.
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Affiliation(s)
- M D Alonso
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, FL 33101
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49
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Alonso MD, Lomako J, Lomako WM, Whelan WJ, Preiss J. Properties of carbohydrate-free recombinant glycogenin expressed in an Escherichia coli mutant lacking UDP-glucose pyrophosphorylase activity. FEBS Lett 1994; 352:222-6. [PMID: 7925977 DOI: 10.1016/0014-5793(94)00962-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Glycogenin, the self-glucosylating primer for glycogen synthesis, is expressed in wild-type E. coli as a recombinant protein in an already partly glucosylated form, owing to the presence of its substrate, UDP-glucose. By using an E. coli mutant strain lacking in UDP-glucose pyrophosphorylase activity, we have succeeded in expressing carbohydrate-free glycogenin (apo-glycogenin) in good yield. When provided with UDPxylose, it autocatalytically adds 1 xylose residue. With UDP-glucose, an average of 8 glucose residues are added. However, release of the self-synthesized maltosaccharide chains with isoamylase reveals them to be a mixture. Chains as long as 11 glucose residues (maltoundecaose) are present. The ability of recombinant apo-glycogenin to self-glucosylate is further proof that a separate enzyme is not needed for the addition of the first glucose residue to Tyr-194 of the protein.
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Affiliation(s)
- M D Alonso
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, FL 33101
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50
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Rodén L, Ananth S, Campbell P, Manzella S, Meezan E. Xylosyl transfer to an endogenous renal acceptor. Purification of the transferase and the acceptor and their identification as glycogenin. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)78153-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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