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McCorvie TJ, Loria PM, Tu M, Han S, Shrestha L, Froese DS, Ferreira IM, Berg AP, Yue WW. Molecular basis for the regulation of human glycogen synthase by phosphorylation and glucose-6-phosphate. Nat Struct Mol Biol 2022; 29:628-638. [PMID: 35835870 PMCID: PMC9287172 DOI: 10.1038/s41594-022-00799-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 05/02/2022] [Indexed: 11/17/2022]
Abstract
Glycogen synthase (GYS1) is the central enzyme in muscle glycogen biosynthesis. GYS1 activity is inhibited by phosphorylation of its amino (N) and carboxyl (C) termini, which is relieved by allosteric activation of glucose-6-phosphate (Glc6P). We present cryo-EM structures at 3.0-4.0 Å resolution of phosphorylated human GYS1, in complex with a minimal interacting region of glycogenin, in the inhibited, activated and catalytically competent states. Phosphorylations of specific terminal residues are sensed by different arginine clusters, locking the GYS1 tetramer in an inhibited state via intersubunit interactions. The Glc6P activator promotes conformational change by disrupting these interactions and increases the flexibility of GYS1, such that it is poised to adopt a catalytically competent state when the sugar donor UDP-glucose (UDP-glc) binds. We also identify an inhibited-like conformation that has not transitioned into the activated state, in which the locking interaction of phosphorylation with the arginine cluster impedes subsequent conformational changes due to Glc6P binding. Our results address longstanding questions regarding the mechanism of human GYS1 regulation.
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Affiliation(s)
- Thomas J McCorvie
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Paula M Loria
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Groton, CT, USA
| | - Meihua Tu
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA
| | - Seungil Han
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Groton, CT, USA
| | - Leela Shrestha
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - D Sean Froese
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, University of Zürich, Zürich, Switzerland
| | - Igor M Ferreira
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Allison P Berg
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA.
| | - Wyatt W Yue
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK.
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2
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Tang B, Frasinyuk MS, Chikwana VM, Mahalingan KK, Morgan CA, Segvich DM, Bondarenko SP, Mrug GP, Wyrebek P, Watt DS, DePaoli-Roach AA, Roach PJ, Hurley TD. Discovery and Development of Small-Molecule Inhibitors of Glycogen Synthase. J Med Chem 2020; 63:3538-3551. [PMID: 32134266 DOI: 10.1021/acs.jmedchem.9b01851] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The overaccumulation of glycogen appears as a hallmark in various glycogen storage diseases (GSDs), including Pompe, Cori, Andersen, and Lafora disease. Accumulating evidence suggests that suppression of glycogen accumulation represents a potential therapeutic approach for treating these GSDs. Using a fluorescence polarization assay designed to screen for inhibitors of the key glycogen synthetic enzyme, glycogen synthase (GS), we identified a substituted imidazole, (rac)-2-methoxy-4-(1-(2-(1-methylpyrrolidin-2-yl)ethyl)-4-phenyl-1H-imidazol-5-yl)phenol (H23), as a first-in-class inhibitor for yeast GS 2 (yGsy2p). Data from X-ray crystallography at 2.85 Å, as well as kinetic data, revealed that H23 bound within the uridine diphosphate glucose binding pocket of yGsy2p. The high conservation of residues between human and yeast GS in direct contact with H23 informed the development of around 500 H23 analogs. These analogs produced a structure-activity relationship profile that led to the identification of a substituted pyrazole, 4-(4-(4-hydroxyphenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl)pyrogallol, with a 300-fold improved potency against human GS. These substituted pyrazoles possess a promising scaffold for drug development efforts targeting GS activity in GSDs associated with excess glycogen accumulation.
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Affiliation(s)
- Buyun Tang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Mykhaylo S Frasinyuk
- V. P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, NAS of Ukraine, Kyiv 02094, Ukraine.,National University of Food Technologies, Kyiv 01601, Ukraine
| | - Vimbai M Chikwana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Krishna K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Cynthia A Morgan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Dyann M Segvich
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | | | - Galyna P Mrug
- V. P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, NAS of Ukraine, Kyiv 02094, Ukraine.,National University of Food Technologies, Kyiv 01601, Ukraine
| | - Przemyslaw Wyrebek
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington 40506, Kentucky, United States.,Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington 40536, Kentucky, United States
| | - David S Watt
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington 40506, Kentucky, United States.,Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington 40536, Kentucky, United States.,Lucille Parker Markey Cancer Center, University of Kentucky, Lexington 40536, Kentucky, United States
| | - Anna A DePaoli-Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Peter J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
| | - Thomas D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, Indiana, United States
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3
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Mahalingan KK, Baskaran S, DePaoli-Roach AA, Roach PJ, Hurley TD. Redox Switch for the Inhibited State of Yeast Glycogen Synthase Mimics Regulation by Phosphorylation. Biochemistry 2016; 56:179-188. [PMID: 27935293 DOI: 10.1021/acs.biochem.6b00884] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Glycogen synthase (GS) is the rate limiting enzyme in the synthesis of glycogen. Eukaryotic GS is negatively regulated by covalent phosphorylation and allosterically activated by glucose-6-phosphate (G-6-P). To gain structural insights into the inhibited state of the enzyme, we solved the crystal structure of yGsy2-R589A/R592A to a resolution of 3.3 Å. The double mutant has an activity ratio similar to the phosphorylated enzyme and also retains the ability to be activated by G-6-P. When compared to the 2.88 Å structure of the wild-type G-6-P activated enzyme, the crystal structure of the low-activity mutant showed that the N-terminal domain of the inhibited state is tightly held against the dimer-related interface thereby hindering acceptor access to the catalytic cleft. On the basis of these two structural observations, we developed a reversible redox regulatory feature in yeast GS by substituting cysteine residues for two highly conserved arginine residues. When oxidized, the cysteine mutant enzyme exhibits activity levels similar to the phosphorylated enzyme but cannot be activated by G-6-P. Upon reduction, the cysteine mutant enzyme regains normal activity levels and regulatory response to G-6-P activation.
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Affiliation(s)
- Krishna K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Sulochanadevi Baskaran
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Anna A DePaoli-Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Peter J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
| | - Thomas D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine , Indianapolis, Indiana 46202, United States
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4
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Maile CA, Hingst JR, Mahalingan KK, O'Reilly AO, Cleasby ME, Mickelson JR, McCue ME, Anderson SM, Hurley TD, Wojtaszewski JFP, Piercy RJ. A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase. Biochim Biophys Acta Gen Subj 2016; 1861:3388-3398. [PMID: 27592162 DOI: 10.1016/j.bbagen.2016.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/15/2016] [Accepted: 08/30/2016] [Indexed: 01/16/2023]
Abstract
BACKGROUND Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. METHODS Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. RESULTS PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. CONCLUSIONS Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. GENERAL SIGNIFICANCE This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.
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Affiliation(s)
- C A Maile
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - J R Hingst
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - K K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - A O O'Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - M E Cleasby
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - J R Mickelson
- Veterinary Biomedical Sciences Department, University of Minnesota, St. Paul, MN, USA
| | - M E McCue
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - S M Anderson
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - T D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - J F P Wojtaszewski
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - R J Piercy
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
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5
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Sawitri WD, Narita H, Ishizaka-Ikeda E, Sugiharto B, Hase T, Nakagawa A. Purification and characterization of recombinant sugarcane sucrose phosphate synthase expressed in E. coli and insect Sf9 cells: an importance of the N-terminal domain for an allosteric regulatory property. J Biochem 2016; 159:599-607. [PMID: 26826371 PMCID: PMC4892393 DOI: 10.1093/jb/mvw004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 09/03/2011] [Accepted: 12/10/2015] [Indexed: 11/13/2022] Open
Abstract
Sucrose phosphate synthase (SPS) catalyses the transfer of glycosyl group of uridine diphosphate glucose to fructose-6-phosphate to form sucrose-6-phosphate. Plant SPS plays a key role in photosynthetic carbon metabolisms, which activity is modulated by an allosteric activator glucose-6-phosphate (G6P). We produced recombinant sugarcane SPS using Escherichia coli and Sf9 insect cells to investigate its structure-function relationship. When expressed in E. coli, two forms of SPS with different sizes appeared; the larger was comparable in size with the authentic plant enzyme and the shorter was trimmed the N-terminal 20 kDa region off. In the insect cells, only enzyme with the authentic size was produced. We purified the trimmed SPS and the full size enzyme from insect cells and found their enzymatic properties differed significantly; the full size enzyme was activated allosterically by G6P, while the trimmed one showed a high activity even without G6P. We further introduced a series of N-terminal truncations up to 171 residue and found G6P-independent activity was enhanced by the truncation. These combined results indicated that the N-terminal region of sugarcane SPS is crucial for the allosteric regulation by G6P and may function like a suppressor domain for the enzyme activity.
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Affiliation(s)
- Widhi Dyah Sawitri
- Research Center for State-of-the-Art Functional Protein Analysis, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hirotaka Narita
- Research Center for State-of-the-Art Functional Protein Analysis, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Etsuko Ishizaka-Ikeda
- Research Center for State-of-the-Art Functional Protein Analysis, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Bambang Sugiharto
- Center for Development of Advanced Science and Technology, Jember University, Jl. Kalimantan No. 37, Kampus Tegalboto, Jember 68121, Indonesia; and
| | - Toshiharu Hase
- Division of Protein Chemistry, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Atsushi Nakagawa
- Research Center for State-of-the-Art Functional Protein Analysis, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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6
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Expression of Genes Encoding the Enzymes for Glycogen and Trehalose Metabolism in L3 and L4 Larvae of Anisakis simplex. J Parasitol Res 2015; 2015:438145. [PMID: 26783451 PMCID: PMC4689960 DOI: 10.1155/2015/438145] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/22/2015] [Indexed: 11/17/2022] Open
Abstract
Trehalose and glycogen metabolism plays an important role in supporting life processes in many nematodes, including Anisakis simplex. Nematodes, cosmopolitan helminths parasitizing sea mammals and humans, cause a disease known as anisakiasis. The aim of this study was to investigate the expression of genes encoding the enzymes involved in the metabolism of trehalose and glycogen—trehalose-6-phosphate synthase (TPS), trehalose-6-phosphate phosphatase (TPP), glycogen synthase (GS), and glycogen phosphorylase (GP)—in stage L3 and stage L4 larvae of A. simplex. The expression of mRNA all four genes, tps, tpp, gs, and gp, was examined by real-time polymerase chain reaction. The A. simplex ribosomal gene (18S) was used as a reference gene. Enzymatic activity was determined. The expression of trehalose enzyme genes was higher in L3 than in L4 larvae, but an inverse relationship was noted for the expression of gs and gp genes.
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7
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Expression and purification of functional human glycogen synthase-1 (hGYS1) in insect cells. Protein Expr Purif 2013; 90:78-83. [PMID: 23711380 DOI: 10.1016/j.pep.2013.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 05/17/2013] [Accepted: 05/18/2013] [Indexed: 01/02/2023]
Abstract
We have successfully expressed and purified active human glycogen synthase-1 (hGYS1). Successful production of the recombinant hGYS1 protein was achieved by co-expression of hGYS1 and rabbit glycogenin (rGYG1) using the MultiBac baculovirus expression system (BEVS). Functional measurements of activity ratios of hGYS1 in the absence and presence of glucose-6-phosphate and treatment with phosphatase indicate that the expressed protein is heavily phosphorylated. We used mass spectrometry to further characterize the sites of phosphorylation, which include most of the known regulatory phosphorylation sites, as well as several sites unique to the insect cell over-expression. Obtaining large quantities of functional hGYS1 will be invaluable for future structural studies as well as detailed studies on the effects on specific sites of phosphorylation.
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8
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Winnick JJ, An Z, Kraft G, Ramnanan CJ, Irimia JM, Smith M, Lautz M, Roach PJ, Cherrington AD. Liver glycogen loading dampens glycogen synthesis seen in response to either hyperinsulinemia or intraportal glucose infusion. Diabetes 2013; 62:96-101. [PMID: 22923473 PMCID: PMC3526057 DOI: 10.2337/db11-1773] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to determine the effect of liver glycogen loading on net hepatic glycogen synthesis during hyperinsulinemia or hepatic portal vein glucose infusion in vivo. Liver glycogen levels were supercompensated (SCGly) in two groups (using intraportal fructose infusion) but not in two others (Gly) during hyperglycemic-normoinsulinemia. Following a 2-h control period during which fructose infusion was stopped, there was a 2-h experimental period in which the response to hyperglycemia plus either 4× basal insulin (INS) or portal vein glucose infusion (PoG) was measured. Increased hepatic glycogen reduced the percent of glucose taken up by the liver that was deposited in glycogen (74 ± 3 vs. 53 ± 5% in Gly+INS and SCGly+INS, respectively, and 72 ± 3 vs. 50 ± 6% in Gly+PoG and SCGly+PoG, respectively). The reduction in liver glycogen synthesis in SCGly+INS was accompanied by a decrease in both insulin signaling and an increase in AMPK activation, whereas only the latter was observed in SCGly+PoG. These data indicate that liver glycogen loading impairs glycogen synthesis regardless of the signal used to stimulate it.
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Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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9
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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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10
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Baskaran S, Chikwana VM, Contreras CJ, Davis KD, Wilson WA, DePaoli-Roach AA, Roach PJ, Hurley TD. Multiple glycogen-binding sites in eukaryotic glycogen synthase are required for high catalytic efficiency toward glycogen. J Biol Chem 2011; 286:33999-4006. [PMID: 21835915 DOI: 10.1074/jbc.m111.264531] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogen synthase is a rate-limiting enzyme in the biosynthesis of glycogen and has an essential role in glucose homeostasis. The three-dimensional structures of yeast glycogen synthase (Gsy2p) complexed with maltooctaose identified four conserved maltodextrin-binding sites distributed across the surface of the enzyme. Site-1 is positioned on the N-terminal domain, site-2 and site-3 are present on the C-terminal domain, and site-4 is located in an interdomain cleft adjacent to the active site. Mutation of these surface sites decreased glycogen binding and catalytic efficiency toward glycogen. Mutations within site-1 and site-2 reduced the V(max)/S(0.5) for glycogen by 40- and 70-fold, respectively. Combined mutation of site-1 and site-2 decreased the V(max)/S(0.5) for glycogen by >3000-fold. Consistent with the in vitro data, glycogen accumulation in glycogen synthase-deficient yeast cells (Δgsy1-gsy2) transformed with the site-1, site-2, combined site-1/site-2, or site-4 mutant form of Gsy2p was decreased by up to 40-fold. In contrast to the glycogen results, the ability to utilize maltooctaose as an in vitro substrate was unaffected in the site-2 mutant, moderately affected in the site-1 mutant, and almost completely abolished in the site-4 mutant. These data show that the ability to utilize maltooctaose as a substrate can be independent of the ability to utilize glycogen. Our data support the hypothesis that site-1 and site-2 provide a "toehold mechanism," keeping glycogen synthase tightly associated with the glycogen particle, whereas site-4 is more closely associated with positioning of the nonreducing end during catalysis.
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Affiliation(s)
- Sulochanadevi Baskaran
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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11
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Hunter RW, Treebak JT, Wojtaszewski JFP, Sakamoto K. Molecular mechanism by which AMP-activated protein kinase activation promotes glycogen accumulation in muscle. Diabetes 2011; 60:766-74. [PMID: 21282366 PMCID: PMC3046837 DOI: 10.2337/db10-1148] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE During energy stress, AMP-activated protein kinase (AMPK) promotes glucose transport and glycolysis for ATP production, while it is thought to inhibit anabolic glycogen synthesis by suppressing the activity of glycogen synthase (GS) to maintain the energy balance in muscle. Paradoxically, chronic activation of AMPK causes an increase in glycogen accumulation in skeletal and cardiac muscles, which in some cases is associated with cardiac dysfunction. The aim of this study was to elucidate the molecular mechanism by which AMPK activation promotes muscle glycogen accumulation. RESEARCH DESIGN AND METHODS We recently generated knock-in mice in which wild-type muscle GS was replaced by a mutant (Arg582Ala) that could not be activated by glucose-6-phosphate (G6P), but possessed full catalytic activity and could still be activated normally by dephosphorylation. Muscles from GS knock-in or transgenic mice overexpressing a kinase dead (KD) AMPK were incubated with glucose tracers and the AMPK-activating compound 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) ex vivo. GS activity and glucose uptake and utilization (glycolysis and glycogen synthesis) were assessed. RESULTS Even though AICAR caused a modest inactivation of GS, it stimulated muscle glycogen synthesis that was accompanied by increases in glucose transport and intracellular [G6P]. These effects of AICAR required the catalytic activity of AMPK. Strikingly, AICAR-induced glycogen synthesis was completely abolished in G6P-insensitive GS knock-in mice, although AICAR-stimulated AMPK activation, glucose transport, and total glucose utilization were normal. CONCLUSIONS We provide genetic evidence that AMPK activation promotes muscle glycogen accumulation by allosteric activation of GS through an increase in glucose uptake and subsequent rise in cellular [G6P].
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Affiliation(s)
- Roger W Hunter
- MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, UK.
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12
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Winnick JJ, An Z, Ramnanan CJ, Smith M, Irimia JM, Neal DW, Moore MC, Roach PJ, Cherrington AD. Hepatic glycogen supercompensation activates AMP-activated protein kinase, impairs insulin signaling, and reduces glycogen deposition in the liver. Diabetes 2011; 60:398-407. [PMID: 21270252 PMCID: PMC3028338 DOI: 10.2337/db10-0592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver's ability to take up and metabolize glucose. RESEARCH DESIGN AND METHODS During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO(2)) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. RESULTS Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P < 0.001), causing a large difference in hepatic glycogen content (62 ± 9 vs. 100 ± 3 mg/g; P < 0.001). Hepatic glycogen supercompensation (fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P < 0.01) and increased the percent directed to lactate (12 ± 3 vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. CONCLUSIONS These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU.
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Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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13
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Wilson WA, Roach PJ, Montero M, Baroja-Fernández E, Muñoz FJ, Eydallin G, Viale AM, Pozueta-Romero J. Regulation of glycogen metabolism in yeast and bacteria. FEMS Microbiol Rev 2011; 34:952-85. [PMID: 20412306 DOI: 10.1111/j.1574-6976.2010.00220.x] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Microorganisms have the capacity to utilize a variety of nutrients and adapt to continuously changing environmental conditions. Many microorganisms, including yeast and bacteria, accumulate carbon and energy reserves to cope with the starvation conditions temporarily present in the environment. Glycogen biosynthesis is a main strategy for such metabolic storage, and a variety of sensing and signaling mechanisms have evolved in evolutionarily distant species to ensure the production of this homopolysaccharide. At the most fundamental level, the processes of glycogen synthesis and degradation in yeast and bacteria share certain broad similarities. However, the regulation of these processes is sometimes quite distinct, indicating that they have evolved separately to respond optimally to the habitat conditions of each species. This review aims to highlight the mechanisms, both at the transcriptional and at the post-transcriptional level, that regulate glycogen metabolism in yeast and bacteria, focusing on selected areas where the greatest increase in knowledge has occurred during the last few years. In the yeast system, we focus particularly on the various signaling pathways that control the activity of the enzymes of glycogen storage. We also discuss our recent understanding of the important role played by the vacuole in glycogen metabolism. In the case of bacterial glycogen, special emphasis is placed on aspects related to the genetic regulation of glycogen metabolism and its connection with other biological processes.
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Affiliation(s)
- Wayne A Wilson
- Biochemistry and Nutrition Department, Des Moines University, Des Moines, IA, USA
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Structural basis for glucose-6-phosphate activation of glycogen synthase. Proc Natl Acad Sci U S A 2010; 107:17563-8. [PMID: 20876143 DOI: 10.1073/pnas.1006340107] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of the storage of glycogen, one of the major energy reserves, is of utmost metabolic importance. In eukaryotes, this regulation is accomplished through glucose-6-phosphate levels and protein phosphorylation. Glycogen synthase homologs in bacteria and archaea lack regulation, while the eukaryotic enzymes are inhibited by protein kinase mediated phosphorylation and activated by protein phosphatases and glucose-6-phosphate binding. We determined the crystal structures corresponding to the basal activity state and glucose-6-phosphate activated state of yeast glycogen synthase-2. The enzyme is assembled into an unusual tetramer by an insertion unique to the eukaryotic enzymes, and this subunit interface is rearranged by the binding of glucose-6-phosphate, which frees the active site cleft and facilitates catalysis. Using both mutagenesis and intein-mediated phospho-peptide ligation experiments, we demonstrate that the enzyme's response to glucose-6-phosphate is controlled by Arg583 and Arg587, while four additional arginine residues present within the same regulatory helix regulate the response to phosphorylation.
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15
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Wilson WA, Boyer MP, Davis KD, Burke M, Roach PJ. The subcellular localization of yeast glycogen synthase is dependent upon glycogen content. Can J Microbiol 2010; 56:408-20. [PMID: 20555403 PMCID: PMC2888498 DOI: 10.1139/w10-027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The budding yeast, Saccharomyces cerevisiae, accumulates the storage polysaccharide glycogen in response to nutrient limitation. Glycogen synthase, the major form of which is encoded by the GSY2 gene, catalyzes the key regulated step in glycogen storage. Here, we utilized Gsy2p fusions to green fluorescent protein (GFP) to determine where glycogen synthase was located within cells. We demonstrated that the localization pattern of Gsy2-GFP depended upon the glycogen content of the cell. When glycogen was abundant, Gsy2-GFP was found uniformly throughout the cytoplasm, but under low glycogen conditions, Gsy2-GFP localized to discrete spots within cells. Gsy2p is known to bind to glycogen, and we propose that the subcellular distribution of Gsy2-GFP reflects the distribution of glycogen particles. In the absence of glycogen, Gsy2p translocates into the nucleus. We hypothesize that Gsy2p is normally retained in the cytoplasm through its interaction with glycogen particles. When glycogen levels are reduced, Gsy2p loses this anchor and can traffic into the nucleus.
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Affiliation(s)
- Wayne A Wilson
- Biochemistry and Nutrition Department, Des Moines University, 3200 Grand Avenue, Des Moines, IA 50312, USA.
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16
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Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis. Genomics 2008; 91:458-66. [PMID: 18358695 DOI: 10.1016/j.ygeno.2008.01.011] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 01/28/2008] [Accepted: 01/29/2008] [Indexed: 11/20/2022]
Abstract
Polysaccharide storage myopathy (PSSM) is a novel glycogenosis in horses characterized by abnormal glycogen accumulation in skeletal muscle and muscle damage with exertion. It is unlike glycogen storage diseases resulting from known defects in glycogenolysis, glycolysis, and glycogen synthesis that have been described in humans and domestic animals. A genome-wide association identified GYS1, encoding skeletal muscle glycogen synthase (GS), as a candidate gene for PSSM. DNA sequence analysis revealed a mutation resulting in an arginine-to-histidine substitution in a highly conserved region of GS. Functional analysis demonstrated an elevated GS activity in PSSM horses, and haplotype analysis and allele age estimation demonstrated that this mutation is identical by descent among horse breeds. This is the first report of a gain-of-function mutation in GYS1 resulting in a glycogenosis.
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Bouskila M, Hirshman MF, Jensen J, Goodyear LJ, Sakamoto K. Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle. Am J Physiol Endocrinol Metab 2008; 294:E28-35. [PMID: 18003720 DOI: 10.1152/ajpendo.00481.2007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6-P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3 alpha and -beta genes are replaced with mutant forms (GSK3 alpha/beta S21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3 alpha/beta S21A/S21A/S9A/S9A mice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6-P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6-P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.
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Buschiazzo A, Ugalde JE, Guerin ME, Shepard W, Ugalde RA, Alzari PM. Crystal structure of glycogen synthase: homologous enzymes catalyze glycogen synthesis and degradation. EMBO J 2004; 23:3196-205. [PMID: 15272305 PMCID: PMC514502 DOI: 10.1038/sj.emboj.7600324] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Accepted: 06/21/2004] [Indexed: 11/10/2022] Open
Abstract
Glycogen and starch are the major readily accessible energy storage compounds in nearly all living organisms. Glycogen is a very large branched glucose homopolymer containing about 90% alpha-1,4-glucosidic linkages and 10% alpha-1,6 linkages. Its synthesis and degradation constitute central pathways in the metabolism of living cells regulating a global carbon/energy buffer compartment. Glycogen biosynthesis involves the action of several enzymes among which glycogen synthase catalyzes the synthesis of the alpha-1,4-glucose backbone. We now report the first crystal structure of glycogen synthase in the presence and absence of adenosine diphosphate. The overall fold and the active site architecture of the protein are remarkably similar to those of glycogen phosphorylase, indicating a common catalytic mechanism and comparable substrate-binding properties. In contrast to glycogen phosphorylase, glycogen synthase has a much wider catalytic cleft, which is predicted to undergo an important interdomain 'closure' movement during the catalytic cycle. The structures also provide useful hints to shed light on the allosteric regulation mechanisms of yeast/mammalian glycogen synthases.
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Affiliation(s)
| | - Juan E Ugalde
- Instituto de Investigaciones Biotecnológicas, Universidad de General San Martín and CONICET, CC 30, San Martín, Argentina
| | - Marcelo E Guerin
- Unité de Biochimie Structurale, URA 2185 CNRS, Institut Pasteur, Paris, France
| | | | - Rodolfo A Ugalde
- Instituto de Investigaciones Biotecnológicas, Universidad de General San Martín and CONICET, CC 30, San Martín, Argentina
| | - Pedro M Alzari
- Unité de Biochimie Structurale, URA 2185 CNRS, Institut Pasteur, Paris, France
- Unité de Biochimie Structurale, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris cedex 15, France. Tel.: +33 1 45 68 8607; Fax: +33 1 45 68 8604; E-mail:
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19
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MacGregor EA. Possible structure and active site residues of starch, glycogen, and sucrose synthases. JOURNAL OF PROTEIN CHEMISTRY 2002; 21:297-306. [PMID: 12168700 DOI: 10.1023/a:1019701621256] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A group of enzymes that include muscle glycogen phosphorylase and sugar transferases involved in, for example, the glucosylation of DNA and the synthesis of peptidoglycan are known to possess the same basic three-dimensional fold. Here the possibility is examined that other monosaccharide transferases, those that catalyze synthesis of starch, glycogen, and the disaccharide sucrose, resemble the phosphorylase-type enzymes in structure. In particular, a clear relationship is shown, for the first time, between mammalian glycogen synthases and the phosphorylase structural group of proteins. Domain architecture and secondary structure are discussed, and the possible role of several conserved amino acids at the active site is explored.
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Affiliation(s)
- E Ann MacGregor
- Department of Chemistry, University of Manitoba, Winnipeg, Canada.
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20
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Anderson C, Tatchell K. Hyperactive glycogen synthase mutants of Saccharomyces cerevisiae suppress the glc7-1 protein phosphatase mutant. J Bacteriol 2001; 183:821-9. [PMID: 11208778 PMCID: PMC94947 DOI: 10.1128/jb.183.3.821-829.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2000] [Accepted: 11/01/2000] [Indexed: 11/20/2022] Open
Abstract
A yeast glc7-1 mutant expressing a variant of protein phosphatase type 1 fails to accumulate glycogen. This defect is associated with hyperphosphorylated and inactive glycogen synthase, consistent with Glc7p acting directly to dephosphorylate and activate glycogen synthase. To characterize the glycogen synthesis defect of this mutant in more detail, we isolated 26 pseudorevertants of the glc7-1 mutant. All pseudoreversion events were due to missense mutations in GSY2, the gene encoding the major isoform of glycogen synthase. A majority of the mutations responsible for the suppression were in the 3' end of the gene, corresponding to the phosphorylated COOH terminus of Gsy2p. Phosphorylation of the mutant proteins was reduced, suggesting that they are poor substrates for glycogen synthase kinases. Suppressor mutations outside this domain did not decrease the phosphorylation of the resulting proteins, indicating that these proteins are immune to the regulatory effects of phosphorylation. Since no growth defect has been observed for strains with altered glycogen levels, the relative levels of fitness of GSY2 mutants that fail to accumulate glycogen and that hyperaccumulate glycogen were assayed by cocultivation experiments. A wild-type strain outcompeted both hypo- and hyperaccumulating strains, suggesting that glycogen levels contribute substantially to the fitness of yeast.
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Affiliation(s)
- C Anderson
- Department of Microbiology, North Carolina State University, Raleigh, North Carolina 27695, USA
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