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Frenett ML, Weis K, Cole MJ, Vargas JCC, Ramsay A, Huang J, Gentry MS, Vander Kooi CW, Raththagala M. Differential activity of glucan phosphatase starch EXcess4 orthologs from agronomic crops. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2022. [DOI: 10.1016/j.bcab.2022.102479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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2
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Murphy RD, Chen T, Lin J, He R, Wu L, Pearson CR, Sharma S, Vander Kooi CD, Sinai AP, Zhang ZY, Vander Kooi CW, Gentry MS. The Toxoplasma glucan phosphatase TgLaforin utilizes a distinct functional mechanism that can be exploited by therapeutic inhibitors. J Biol Chem 2022; 298:102089. [PMID: 35640720 PMCID: PMC9254107 DOI: 10.1016/j.jbc.2022.102089] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 01/19/2023] Open
Abstract
Toxoplasma gondii is an intracellular parasite that generates amylopectin granules (AGs), a polysaccharide associated with bradyzoites that define chronic T. gondii infection. AGs are postulated to act as an essential energy storage molecule that enable bradyzoite persistence, transmission, and reactivation. Importantly, reactivation can result in the life-threatening symptoms of toxoplasmosis. T. gondii encodes glucan dikinase and glucan phosphatase enzymes that are homologous to the plant and animal enzymes involved in reversible glucan phosphorylation and which are required for efficient polysaccharide degradation and utilization. However, the structural determinants that regulate reversible glucan phosphorylation in T. gondii are unclear. Herein, we define key functional aspects of the T. gondii glucan phosphatase TgLaforin (TGME49_205290). We demonstrate that TgLaforin possesses an atypical split carbohydrate-binding-module domain. AlphaFold2 modeling combined with hydrogen-deuterium exchange mass spectrometry and differential scanning fluorimetry also demonstrate the unique structural dynamics of TgLaforin with regard to glucan binding. Moreover, we show that TgLaforin forms a dual specificity phosphatase domain-mediated dimer. Finally, the distinct properties of the glucan phosphatase catalytic domain were exploited to identify a small molecule inhibitor of TgLaforin catalytic activity. Together, these studies define a distinct mechanism of TgLaforin activity, opening up a new avenue of T. gondii bradyzoite biology as a therapeutic target.
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Affiliation(s)
- Robert D Murphy
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA; Department of Microbiology, Immunology, and Molecular Genetics, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Tiantian Chen
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Jianping Lin
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Purdue Institute for Drug Discovery, Purdue University, West Lafayette, Indiana, USA
| | - Rongjun He
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Purdue Institute for Drug Discovery, Purdue University, West Lafayette, Indiana, USA
| | - Li Wu
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Purdue Institute for Drug Discovery, Purdue University, West Lafayette, Indiana, USA
| | - Caden R Pearson
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Savita Sharma
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Carl D Vander Kooi
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Anthony P Sinai
- Department of Microbiology, Immunology, and Molecular Genetics, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Zhong-Yin Zhang
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Purdue Institute for Drug Discovery, Purdue University, West Lafayette, Indiana, USA.
| | - Craig W Vander Kooi
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA.
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, Kentucky, USA.
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3
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Mak CA, Weis K, Henao T, Kuchtova A, Chen T, Sharma S, Meekins DA, Thalmann M, Vander Kooi CW, Raththagala M. Cooperative Kinetics of the Glucan Phosphatase Starch Excess4. Biochemistry 2021; 60:2425-2435. [PMID: 34319705 DOI: 10.1021/acs.biochem.1c00307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glucan phosphatases are members of a functionally diverse family of dual-specificity phosphatase (DSP) enzymes. The plant glucan phosphatase Starch Excess4 (SEX4) binds and dephosphorylates glucans, contributing to processive starch degradation in the chloroplast at night. Little is known about the complex kinetics of SEX4 when acting on its complex physiologically relevant glucan substrate. Therefore, we explored the kinetics of SEX4 against both insoluble starch and soluble amylopectin glucan substrates. SEX4 displays robust activity and a unique sigmoidal kinetic response to amylopectin, characterized by a Hill coefficient of 2.77 ± 0.63, a signature feature of cooperativity. We investigated the basis for this positive kinetic cooperativity and determined that the SEX4 carbohydrate-binding module (CBM) dramatically influences the binding cooperativity and substrate transformation rates. These findings provide insights into a previously unknown but important regulatory role for SEX4 in reversible starch phosphorylation and further advances our understanding of atypical kinetic mechanisms.
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Affiliation(s)
- Claudia A Mak
- Department of Chemistry, Skidmore College, Saratoga Springs, New York 12866, United States
| | - Kenyon Weis
- Department of Chemistry, Skidmore College, Saratoga Springs, New York 12866, United States
| | - Tiffany Henao
- Department of Chemistry, Skidmore College, Saratoga Springs, New York 12866, United States
| | - Andrea Kuchtova
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40506, United States
| | - Tiantian Chen
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40506, United States
| | - Savita Sharma
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40506, United States
| | - David A Meekins
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40506, United States
| | - Matthias Thalmann
- The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Craig W Vander Kooi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40506, United States
| | - Madushi Raththagala
- Department of Chemistry, Skidmore College, Saratoga Springs, New York 12866, United States
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4
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Sullivan MA, Nitschke S, Skwara EP, Wang P, Zhao X, Pan XS, Chown EE, Wang T, Perri AM, Lee JPY, Vilaplana F, Minassian BA, Nitschke F. Skeletal Muscle Glycogen Chain Length Correlates with Insolubility in Mouse Models of Polyglucosan-Associated Neurodegenerative Diseases. Cell Rep 2020; 27:1334-1344.e6. [PMID: 31042462 DOI: 10.1016/j.celrep.2019.04.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/29/2019] [Accepted: 04/02/2019] [Indexed: 01/31/2023] Open
Abstract
Lafora disease (LD) and adult polyglucosan body disease (APBD) are glycogen storage diseases characterized by a pathogenic buildup of insoluble glycogen. Mechanisms causing glycogen insolubility are poorly understood. Here, in two mouse models of LD (Epm2a-/- and Epm2b-/-) and one of APBD (Gbe1ys/ys), the separation of soluble and insoluble muscle glycogen is described, enabling separate analysis of each fraction. Total glycogen is increased in LD and APBD mice, which, together with abnormal chain length and molecule size distributions, is largely if not fully attributed to insoluble glycogen. Soluble glycogen consists of molecules with distinct chain length distributions and differential corresponding solubility, providing a mechanistic link between soluble and insoluble glycogen in vivo. Phosphorylation states differ across glycogen fractions and mouse models, demonstrating that hyperphosphorylation is not a basic feature of insoluble glycogen. Lastly, model-specific variances in protein and activity levels of key glycogen synthesis enzymes suggest uninvestigated regulatory mechanisms.
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Affiliation(s)
- Mitchell A Sullivan
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Glycation and Diabetes, Translational Research Institute, Mater Research Institute - University of Queensland, Brisbane, QLD 4102, Australia
| | - Silvia Nitschke
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Evan P Skwara
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Peixiang Wang
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Xiao S Pan
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Erin E Chown
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Travis Wang
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Jennifer P Y Lee
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Francisco Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm 10691, Sweden
| | - Berge A Minassian
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada; Division of Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Felix Nitschke
- Program in Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada.
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5
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Brewer MK, Putaux JL, Rondon A, Uittenbogaard A, Sullivan MA, Gentry MS. Polyglucosan body structure in Lafora disease. Carbohydr Polym 2020; 240:116260. [PMID: 32475552 DOI: 10.1016/j.carbpol.2020.116260] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/16/2020] [Accepted: 04/03/2020] [Indexed: 12/18/2022]
Abstract
Abnormal carbohydrate structures known as polyglucosan bodies (PGBs) are associated with neurological disorders, glycogen storage diseases (GSDs), and aging. A hallmark of the GSD Lafora disease (LD), a fatal childhood epilepsy caused by recessive mutations in the EPM2A or EPM2B genes, are cytoplasmic PGBs known as Lafora bodies (LBs). LBs result from aberrant glycogen metabolism and drive disease progression. They are abundant in brain, muscle and heart of LD patients and Epm2a-/- and Epm2b-/- mice. LBs and PGBs are histologically reminiscent of starch, semicrystalline carbohydrates synthesized for glucose storage in plants. In this study, we define LB architecture, tissue-specific differences, and dynamics. We propose a model for how small polyglucosans aggregate to form LBs. LBs are very similar to PGBs of aging and other neurological disorders, and so these studies have direct relevance to the general understanding of PGB structure and formation.
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Affiliation(s)
- M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA; Lafora Epilepsy Cure Initiative, Epilepsy and Brain Metabolism Center, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, 40536, USA; Institute for Research in Biomedicine (IRB Barcelona), 08028, Barcelona, Spain
| | - Jean-Luc Putaux
- Univ. Grenoble Alpes, CNRS, CERMAV, F-38000, Grenoble, France
| | - Alberto Rondon
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Annette Uittenbogaard
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Mitchell A Sullivan
- Glycation and Diabetes Group, Mater Research Institute-The University of Queensland, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA; Lafora Epilepsy Cure Initiative, Epilepsy and Brain Metabolism Center, and Center for Structural Biology, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
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6
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Carrillo JB, Torresi F, Morales LL, Ricordi M, Gomez-Casati DF, Busi MV, Martín M. Identification and characterization of ChlreSEX4, a novel glucan phosphatase from Chlamydomonas reinhardtii green alga. Arch Biochem Biophys 2020; 680:108235. [PMID: 31877265 DOI: 10.1016/j.abb.2019.108235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 12/18/2019] [Accepted: 12/20/2019] [Indexed: 11/16/2022]
Abstract
Chlamydomonas reinhardtii is the best known unicellular green alga model which has long been used to investigate all kinds of cellular processes, including starch metabolism. Here we identified and characterized a novel enzyme, ChlreSEX4, orthologous to glucan phosphatase SEX4 from Arabidopsis thaliana, that is capable of binding and dephosphorylating amylopectin in vitro. We also reported that cysteine 224 and tryptophan 305 residues are critical for enzyme catalysis and substrate binding. Furthermore, we verified that ChlreSEX4 gene is expressed in vivo and that glucan phosphatase activity is measurable in Chlamydomonas protein extracts. In view of the results presented, we suggest ChlreSEX4 as a functional phosphoglucan phosphatase from C. reinhardtii. Our data obtained so far contribute to understanding the phosphoglucan phosphatases evolutionary process in the green lineage and their role in starch reversible phosphorylation. In addition, this allows to position Chlamydomonas as a potential tool to obtain starches with different degrees of phosphorylation for industrial or biotechnological purposes.
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Affiliation(s)
- Julieta B Carrillo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Florencia Torresi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Luisina L Morales
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Micaela Ricordi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Diego F Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Maria V Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina.
| | - Mariana Martín
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina.
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7
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Brewer MK, Uittenbogaard A, Austin GL, Segvich DM, DePaoli-Roach A, Roach PJ, McCarthy JJ, Simmons ZR, Brandon JA, Zhou Z, Zeller J, Young LEA, Sun RC, Pauly JR, Aziz NM, Hodges BL, McKnight TR, Armstrong DD, Gentry MS. Targeting Pathogenic Lafora Bodies in Lafora Disease Using an Antibody-Enzyme Fusion. Cell Metab 2019; 30:689-705.e6. [PMID: 31353261 PMCID: PMC6774808 DOI: 10.1016/j.cmet.2019.07.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 05/28/2019] [Accepted: 07/03/2019] [Indexed: 12/15/2022]
Abstract
Lafora disease (LD) is a fatal childhood epilepsy caused by recessive mutations in either the EPM2A or EPM2B gene. A hallmark of LD is the intracellular accumulation of insoluble polysaccharide deposits known as Lafora bodies (LBs) in the brain and other tissues. In LD mouse models, genetic reduction of glycogen synthesis eliminates LB formation and rescues the neurological phenotype. Therefore, LBs have become a therapeutic target for ameliorating LD. Herein, we demonstrate that human pancreatic α-amylase degrades LBs. We fused this amylase to a cell-penetrating antibody fragment, and this antibody-enzyme fusion (VAL-0417) degrades LBs in vitro and dramatically reduces LB loads in vivo in Epm2a-/- mice. Using metabolomics and multivariate analysis, we demonstrate that VAL-0417 treatment of Epm2a-/- mice reverses the metabolic phenotype to a wild-type profile. VAL-0417 is a promising drug for the treatment of LD and a putative precision therapy platform for intractable epilepsy.
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Affiliation(s)
- M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Annette Uittenbogaard
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Grant L Austin
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Dyann M Segvich
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Anna DePaoli-Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Lafora Epilepsy Cure Initiative, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Peter J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Lafora Epilepsy Cure Initiative, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - John J McCarthy
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Zoe R Simmons
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jason A Brandon
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Zhengqiu Zhou
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jill Zeller
- Northern Biomedical Research, Spring Lake, MI 49456, USA
| | - Lyndsay E A Young
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Ramon C Sun
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - James R Pauly
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA
| | | | | | | | | | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA; Lafora Epilepsy Cure Initiative, University of Kentucky College of Medicine, Lexington, KY 40536, USA; University of Kentucky Epilepsy & Brain Metabolism Alliance, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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8
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Janeček Š, Mareček F, MacGregor EA, Svensson B. Starch-binding domains as CBM families-history, occurrence, structure, function and evolution. Biotechnol Adv 2019; 37:107451. [PMID: 31536775 DOI: 10.1016/j.biotechadv.2019.107451] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/01/2019] [Accepted: 09/15/2019] [Indexed: 01/05/2023]
Abstract
The term "starch-binding domain" (SBD) has been applied to a domain within an amylolytic enzyme that gave the enzyme the ability to bind onto raw, i.e. thermally untreated, granular starch. An SBD is a special case of a carbohydrate-binding domain, which in general, is a structurally and functionally independent protein module exhibiting no enzymatic activity but possessing potential to target the catalytic domain to the carbohydrate substrate to accommodate it and process it at the active site. As so-called families, SBDs together with other carbohydrate-binding modules (CBMs) have become an integral part of the CAZy database (http://www.cazy.org/). The first two well-described SBDs, i.e. the C-terminal Aspergillus-type and the N-terminal Rhizopus-type have been assigned the families CBM20 and CBM21, respectively. Currently, among the 85 established CBM families in CAZy, fifteen can be considered as families having SBD functional characteristics: CBM20, 21, 25, 26, 34, 41, 45, 48, 53, 58, 68, 69, 74, 82 and 83. All known SBDs, with the exception of the extra long CBM74, were recognized as a module consisting of approximately 100 residues, adopting a β-sandwich fold and possessing at least one carbohydrate-binding site. The present review aims to deliver and describe: (i) the SBD identification in different amylolytic and related enzymes (e.g., CAZy GH families) as well as in other relevant enzymes and proteins (e.g., laforin, the β-subunit of AMPK, and others); (ii) information on the position in the polypeptide chain and the number of SBD copies and their CBM family affiliation (if appropriate); (iii) structure/function studies of SBDs with a special focus on solved tertiary structures, in particular, as complexes with α-glucan ligands; and (iv) the evolutionary relationships of SBDs in a tree common to all SBD CBM families (except for the extra long CBM74). Finally, some special cases and novel potential SBDs are also introduced.
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Affiliation(s)
- Štefan Janeček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, SK-84551 Bratislava, Slovakia; Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius, Nám. J. Herdu 2, SK-91701 Trnava, Slovakia.
| | - Filip Mareček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, SK-84551 Bratislava, Slovakia; Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius, Nám. J. Herdu 2, SK-91701 Trnava, Slovakia
| | - E Ann MacGregor
- 2 Nicklaus Green, Livingston EH54 8RX, West Lothian, United Kingdom
| | - Birte Svensson
- Enzyme and Protein Chemistry, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800 Kgs. Lyngby, Denmark
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9
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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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10
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Garcia-Gimeno MA, Rodilla-Ramirez PN, Viana R, Salas-Puig X, Brewer MK, Gentry MS, Sanz P. A novel EPM2A mutation yields a slow progression form of Lafora disease. Epilepsy Res 2018; 145:169-177. [PMID: 30041081 DOI: 10.1016/j.eplepsyres.2018.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/11/2018] [Accepted: 07/13/2018] [Indexed: 12/19/2022]
Abstract
Lafora disease (LD, OMIM 254780) is a rare disorder characterized by epilepsy and neurodegeneration leading patients to a vegetative state and death, usually within the first decade from the onset of the first symptoms. In the vast majority of cases LD is related to mutations in either the EPM2A gene (encoding the glucan phosphatase laforin) or the EPM2B gene (encoding the E3-ubiquitin ligase malin). In this work, we characterize the mutations present in the EPM2A gene in a patient displaying a slow progression form of the disease. The patient is compound heterozygous with Y112X and N163D mutations in the corresponding alleles. In primary fibroblasts obtained from the patient, we analyzed the expression of the mutated alleles by quantitative real time PCR and found slightly lower levels of expression of the EPM2A gene respect to control cells. However, by Western blotting we were unable to detect endogenous levels of the protein in crude extracts from patient fibroblasts. The Y112X mutation would render a truncated protein lacking the phosphatase domain and likely degraded. Since minute amounts of laforin-N163D might still play a role in cell physiology, we analyzed the biochemical characteristics of the N163D mutation. We found that recombinant laforin N163D protein was as stable as wild type and exhibited near wild type phosphatase activity towards biologically relevant substrates. On the contrary, it showed a severe impairment in the interaction profile with previously identified laforin binding partners. These results lead us to conclude that the slow progression of the disease present in this patient could be either due to the specific biochemical properties of laforin N163D or to the presence of alternative genetic modifying factors separate from pathogenicity.
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Affiliation(s)
| | | | - Rosa Viana
- IBV-CSIC. Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Xavier Salas-Puig
- Epilepsy Unit, Neurology Dept., Hospital Vall Hebron, Barcelona, Spain
| | - M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, USA; Lafora Epilepsy Cure Initiative, USA
| | - Pascual Sanz
- IBV-CSIC. Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain; CIBERER. Centro de Investigación Biomédica en Red de Enfermedades Raras, Valencia, Spain; Lafora Epilepsy Cure Initiative, USA.
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11
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Nitschke F, Sullivan MA, Wang P, Zhao X, Chown EE, Perri AM, Israelian L, Juana-López L, Bovolenta P, Rodríguez de Córdoba S, Steup M, Minassian BA. Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease. EMBO Mol Med 2018; 9:906-917. [PMID: 28536304 PMCID: PMC5494504 DOI: 10.15252/emmm.201707608] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss-of-function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase-inactive laforin rescues the laforin-deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin- or malin-deficient mouse lines expressing phosphatase-inactive laforin. We find that: (i) in laforin-deficient mice, phosphatase-inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin-deficient mice, phosphatase-inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD We conclude that laforin's principle function is to control glycogen chain lengths, in a malin-dependent fashion, and that loss of this control underlies LD.
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Affiliation(s)
- Felix Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Mitchell A Sullivan
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Glycation and Diabetes, Mater Research Institute, Translational Research Institute, The University of Queensland, Brisbane, Qld, Australia
| | - Peixiang Wang
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Xiaochu Zhao
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Erin E Chown
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Ami M Perri
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Lori Israelian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Lucia Juana-López
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades Raras, Madrid, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM and Ciber de Enfermedades Raras, Universidad Autónoma de Madrid, Madrid, Spain
| | - Santiago Rodríguez de Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades Raras, Madrid, Spain
| | - Martin Steup
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Berge A Minassian
- Program in Genetics and Genome Biology, The Hospital for Sick Children Research Institute, Toronto, ON, Canada .,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, USA
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12
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Kuchtová A, Gentry MS, Janeček Š. The unique evolution of the carbohydrate-binding module CBM20 in laforin. FEBS Lett 2018; 592:586-598. [PMID: 29389008 DOI: 10.1002/1873-3468.12994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/20/2018] [Accepted: 01/23/2018] [Indexed: 12/30/2022]
Abstract
Laforin catalyses glycogen dephosphorylation. Mutations in its gene result in Lafora disease, a fatal progressive myoclonus epilepsy, the hallmark being water-insoluble, hyperphosphorylated carbohydrate inclusions called Lafora bodies. Human laforin consists of an N-terminal carbohydrate-binding module (CBM) from family CBM20 and a C-terminal dual-specificity phosphatase domain. Laforin is conserved in all vertebrates, some basal metazoans and a small group of protozoans. The present in silico study defines the evolutionary relationships among the CBM20s of laforin with an emphasis on newly identified laforin orthologues. The study reveals putative laforin orthologues in Trichinella, a parasitic nematode, and identifies two sequence inserts in the CBM20 of laforin from parasitic coccidia. Finally, we identify that the putative laforin orthologues from some protozoa and algae possess more than one CBM20.
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Affiliation(s)
- Andrea Kuchtová
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia.,Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Štefan Janeček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia.,Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius, Trnava, Slovakia
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13
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Carrillo JB, Gomez-Casati DF, Martín M, Busi MV. Identification and analysis of OsttaDSP, a phosphoglucan phosphatase from Ostreococcus tauri. PLoS One 2018; 13:e0191621. [PMID: 29360855 PMCID: PMC5779698 DOI: 10.1371/journal.pone.0191621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/08/2018] [Indexed: 11/18/2022] Open
Abstract
Ostreococcus tauri, the smallest free-living (non-symbiotic) eukaryote yet described, is a unicellular green alga of the Prasinophyceae family. It has a very simple cellular organization and presents a unique starch granule and chloroplast. However, its starch metabolism exhibits a complexity comparable to higher plants, with multiple enzyme forms for each metabolic reaction. Glucan phosphatases, a family of enzymes functionally conserved in animals and plants, are essential for normal starch or glycogen degradation in plants and mammals, respectively. Despite the importance of O. tauri microalgae in evolution, there is no information available concerning the enzymes involved in reversible phosphorylation of starch. Here, we report the molecular cloning and heterologous expression of the gene coding for a dual specific phosphatase from O. tauri (OsttaDSP), homologous to Arabidopsis thaliana LSF2. The recombinant enzyme was purified to electrophoretic homogeneity to characterize its oligomeric and kinetic properties accurately. OsttaDSP is a homodimer of 54.5 kDa that binds and dephosphorylates amylopectin. Also, we also determined that residue C162 is involved in catalysis and possibly also in structural stability of the enzyme. Our results could contribute to better understand the role of glucan phosphatases in the metabolism of starch in green algae.
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Affiliation(s)
- Julieta B. Carrillo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Diego F. Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Mariana Martín
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
- * E-mail: (MM); (MVB)
| | - Maria V. Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
- * E-mail: (MM); (MVB)
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14
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Fungal Hybrid B heme peroxidases - unique fusions of a heme peroxidase domain with a carbohydrate-binding domain. Sci Rep 2017; 7:9393. [PMID: 28839281 PMCID: PMC5571214 DOI: 10.1038/s41598-017-09581-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/26/2017] [Indexed: 01/03/2023] Open
Abstract
Heme peroxidases, essential peroxide converting oxidoreductases are divided into four independently evolved superfamilies. Within the largest one – the peroxidase-catalase superfamily - two hybrid lineages were described recently. Whereas Hybrid A heme peroxidases represent intermediate enzymes between ascorbate peroxidases and cytochrome c peroxidases, Hybrid B heme peroxidases are unique fusion proteins comprised of a conserved N-terminal heme peroxidase domain and a C-terminal domain of various sugar binding motifs. So far these peculiar peroxidases are only found in the kingdom of Fungi. Here we present a phylogenetic reconstruction of the whole superfamily with focus on Hybrid B peroxidases. We analyse the domain assembly and putative structure and function of the newly discovered oligosaccharide binding domains. Two distinct carbohydrate binding modules (CBM21 and CBM34) are shown to occur in phytopathogenic ascomycetous orthologs of Hybrid B heme peroxidases only. Based on multiple sequence alignment and homology modeling the structure-function relationships are discussed with respect to physiological function. A concerted action of peroxide cleavage with specific cell-wall carbohydrate binding can support phytopathogens survival within the plant host.
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15
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Pathogenesis of Lafora Disease: Transition of Soluble Glycogen to Insoluble Polyglucosan. Int J Mol Sci 2017; 18:ijms18081743. [PMID: 28800070 PMCID: PMC5578133 DOI: 10.3390/ijms18081743] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/04/2017] [Accepted: 08/06/2017] [Indexed: 02/07/2023] Open
Abstract
Lafora disease (LD, OMIM #254780) is a rare, recessively inherited neurodegenerative disease with adolescent onset, resulting in progressive myoclonus epilepsy which is fatal usually within ten years of symptom onset. The disease is caused by loss-of-function mutations in either of the two genes EPM2A (laforin) or EPM2B (malin). It characteristically involves the accumulation of insoluble glycogen-derived particles, named Lafora bodies (LBs), which are considered neurotoxic and causative of the disease. The pathogenesis of LD is therefore centred on the question of how insoluble LBs emerge from soluble glycogen. Recent data clearly show that an abnormal glycogen chain length distribution, but neither hyperphosphorylation nor impairment of general autophagy, strictly correlates with glycogen accumulation and the presence of LBs. This review summarizes results obtained with patients, mouse models, and cell lines and consolidates apparent paradoxes in the LD literature. Based on the growing body of evidence, it proposes that LD is predominantly caused by an impairment in chain-length regulation affecting only a small proportion of the cellular glycogen. A better grasp of LD pathogenesis will further develop our understanding of glycogen metabolism and structure. It will also facilitate the development of clinical interventions that appropriately target the underlying cause of LD.
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16
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Janeček Š, Majzlová K, Svensson B, MacGregor EA. The starch-binding domain family CBM41-Anin silicoanalysis of evolutionary relationships. Proteins 2017; 85:1480-1492. [DOI: 10.1002/prot.25309] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 04/05/2017] [Accepted: 04/17/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Štefan Janeček
- Institute of Molecular Biology, Slovak Academy of Sciences; Bratislava Slovakia
- Department of Biology; Faculty of Natural Sciences, University of SS. Cyril and Methodius; Trnava Slovakia
| | - Katarína Majzlová
- Institute of Molecular Biology, Slovak Academy of Sciences; Bratislava Slovakia
| | - Birte Svensson
- Department of Biotechnology and Biomedicine; Technical University of Denmark; Kgs. Lyngby Denmark
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17
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Gentry MS, Brewer MK, Vander Kooi CW. Structural biology of glucan phosphatases from humans to plants. Curr Opin Struct Biol 2016; 40:62-69. [PMID: 27498086 PMCID: PMC5161650 DOI: 10.1016/j.sbi.2016.07.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 07/11/2016] [Accepted: 07/21/2016] [Indexed: 02/07/2023]
Abstract
Glucan phosphatases are functionally conserved at the enzymatic level, dephosphorylating glycogen in animals and starch in plants. The human glucan phosphatase laforin is the founding member of the family and it is comprised of a carbohydrate binding module (CBM) domain followed by a dual specificity phosphatase (DSP) domain. Plants encode two glucan phosphatases: Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2). SEX4 contains a DSP domain followed by a CBM domain, while LSF2 contains a DSP domain and lacks a CBM. This review demonstrates how glucan phosphatase function is conserved and highlights how each family member employs a unique mechanism to bind and dephosphorylate glucan substrates.
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Affiliation(s)
- Matthew S Gentry
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536, United States.
| | - M Kathryn Brewer
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536, United States
| | - Craig W Vander Kooi
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536, United States.
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18
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Janeček Š, Gabriško M. Remarkable evolutionary relatedness among the enzymes and proteins from the α-amylase family. Cell Mol Life Sci 2016; 73:2707-25. [PMID: 27154042 PMCID: PMC11108405 DOI: 10.1007/s00018-016-2246-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 12/17/2022]
Abstract
The α-amylase is a ubiquitous starch hydrolase catalyzing the cleavage of the α-1,4-glucosidic bonds in an endo-fashion. Various α-amylases originating from different taxonomic sources may differ from each other significantly in their exact substrate preference and product profile. Moreover, it also seems to be clear that at least two different amino acid sequences utilizing two different catalytic machineries have evolved to execute the same α-amylolytic specificity. The two have been classified in the Cabohydrate-Active enZyme database, the CAZy, in the glycoside hydrolase (GH) families GH13 and GH57. While the former and the larger α-amylase family GH13 evidently forms the clan GH-H with the families GH70 and GH77, the latter and the smaller α-amylase family GH57 has only been predicted to maybe define a future clan with the family GH119. Sequences and several tens of enzyme specificities found throughout all three kingdoms in many taxa provide an interesting material for evolutionarily oriented studies that have demonstrated remarkable observations. This review emphasizes just the three of them: (1) a close relatedness between the plant and archaeal α-amylases from the family GH13; (2) a common ancestry in the family GH13 of animal heavy chains of heteromeric amino acid transporter rBAT and 4F2 with the microbial α-glucosidases; and (3) the unique sequence features in the primary structures of amylomaltases from the genus Borrelia from the family GH77. Although the three examples cannot represent an exhaustive list of exceptional topics worth to be interested in, they may demonstrate the importance these enzymes possess in the overall scientific context.
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Affiliation(s)
- Štefan Janeček
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551, Bratislava, Slovakia.
- Department of Biology, Faculty of Natural Sciences, University of SS. Cyril and Methodius in Trnava, Nám. J. Herdu 2, 91701, Trnava, Slovakia.
| | - Marek Gabriško
- Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551, Bratislava, Slovakia
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19
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Mahlow S, Orzechowski S, Fettke J. Starch phosphorylation: insights and perspectives. Cell Mol Life Sci 2016; 73:2753-64. [PMID: 27147464 PMCID: PMC11108486 DOI: 10.1007/s00018-016-2248-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 01/12/2023]
Abstract
During starch metabolism, the phosphorylation of glucosyl residues of starch, to be more precise of amylopectin, is a repeatedly observed process. This phosphorylation is mediated by dikinases, the glucan, water dikinase (GWD) and the phosphoglucan, water dikinase (PWD). The starch-related dikinases utilize ATP as dual phosphate donor transferring the terminal γ-phosphate group to water and the β-phosphate group selectively to either C6 position or C3 position of a glucosyl residue within amylopectin. By the collaborative action of both enzymes, the initiation of a transition of α-glucans from highly ordered, water-insoluble state to a less order state is realized and thus the initial process of starch degradation. Consequently, mutants lacking either GWD or PWD reveal a starch excess phenotype as well as growth retardation. In this review, we focus on the increased knowledge collected over the last years related to enzymatic properties, the precise definition of the substrates, the physiological implications, and discuss ongoing questions.
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Affiliation(s)
- Sebastian Mahlow
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany
- Institute of General Botany, Friedrich Schiller University Jena, Am Planetarium 1, 07743, Jena, Germany
| | - Sławomir Orzechowski
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany
- Department of Biochemistry, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Joerg Fettke
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany.
- Department of Biochemistry, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland.
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