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Marín-Quílez A, Di Buduo CA, Benito R, Balduini A, Rivera J, Bastida JM. GALE variants associated with syndromic manifestations, macrothrombocytopenia, bleeding, and platelet dysfunction. Platelets 2023; 34:2176699. [PMID: 36846897 DOI: 10.1080/09537104.2023.2176699] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
GALE gene encodes the uridine diphosphate [UDP]-galactose-4-epimerase, which catalyzes the bidirectional interconversion of UDP-glucose to UDP-galactose, and UDP-N-acetyl-glucosamine to UDP-N-acetyl-galactosamine. In that way, GALE balances, through reversible epimerization, the pool of four sugars that are essential during the biosynthesis of glycoproteins and glycolipids. GALE-related disorder presents an autosomal recessive inheritance pattern, and it is commonly associated with galactosemia. Peripheral galactosemia generally associates with non-generalized forms or even asymptomatic presentations, while classical galactosemia may be related to complications such as learning difficulties, developmental delay, cardiac failure, or dysmorphic features. Recently, GALE variants have been related to severe thrombocytopenia, pancytopenia, and in one patient, to myelodysplastic syndrome.
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Affiliation(s)
- Ana Marín-Quílez
- IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain.,Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, Murcia, Spain
| | | | - Rocío Benito
- IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
| | - Alessandra Balduini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Department of Biomedical Engineering, Tufts University, Medford, MA, USA
| | - José Rivera
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, Murcia, Spain
| | - Jose Maria Bastida
- Department of Hematology, Complejo Asistencial Universitario de Salamanca (CAUSA), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca (USAL), Salamanca, Spain
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2
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Nagode A, Vanbeselaere J, Dutkiewicz Z, Kaltenbrunner S, Wilson IBH, Duchêne M. Molecular characterisation of Entamoeba histolytica UDP-glucose 4-epimerase, an enzyme able to provide building blocks for cyst wall formation. PLoS Negl Trop Dis 2023; 17:e0011574. [PMID: 37616327 PMCID: PMC10482301 DOI: 10.1371/journal.pntd.0011574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 09/06/2023] [Accepted: 08/06/2023] [Indexed: 08/26/2023] Open
Abstract
In the human host, the protozoan parasite Entamoeba histolytica is adapted to a non-invasive lifestyle in the colon as well as to an invasive lifestyle in the mesenterial blood vessels and the liver. This means to cope with bacteria and human cells as well as various metabolic challenges. Galactose and N-acetylgalactosamine (GalNAc) are sugars of great importance for the amoebae, they attach to the host mucus and enterocytes via their well-studied Gal/GalNAc specific lectin, they carry galactose residues in their surface glycans, and they cleave GalNAc from host mucins. The enzyme UDP-glucose 4-epimerase (GalE) works as a bridge between the galactose and glucose worlds, it can help to generate glucose for glycolysis from phagocytosis products containing galactose as well as providing UDP-galactose necessary for the biosynthesis of galactose-containing surface components. E. histolytica contains a single galE gene. We recombinantly expressed the enzyme in Escherichia coli and used a spectrophotometric assay to determine its temperature and pH dependency (37°C, pH 8.5), its kinetics for UDP-glucose (Km = 31.82 μM, Vmax = 4.31 U/mg) and substrate spectrum. As observed via RP-HPLC, the enzyme acts on UDP-Glc/Gal as well as UDP-GlcNAc/GalNAc. Previously, Trypanosoma brucei GalE and the bloodstream form of the parasite were shown to be susceptible to the three compounds ebselen, a selenoorganic drug with antioxidant properties, diethylstilbestrol, a mimic of oestrogen with anti-inflammatory properties, and ethacrynic acid, a loop diuretic used to treat oedema. In this study, the three compounds had cytotoxic activity against E. histolytica, but only ebselen inhibited the recombinant GalE with an IC50 of 1.79 μM (UDP-Gal) and 1.2 μM (UDP-GalNAc), suggesting that the two other compounds are active against other targets in the parasite. The importance of the ability of GalE to interconvert UDP-GalNAc and UDP-GlcNAc may be that the trophozoites can generate precursors for their own cyst wall from the sugar subunits cleaved from host mucins. This finding advances our understanding of the biochemical interactions of E. histolytica in its colonic environment.
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Affiliation(s)
- Anna Nagode
- Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | | | - Samantha Kaltenbrunner
- Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Iain B. H. Wilson
- Department of Chemistry, Universität für Bodenkultur, Vienna, Austria
| | - Michael Duchêne
- Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
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3
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Marín-Quílez A, Di Buduo CA, Díaz-Ajenjo L, Abbonante V, Vuelta E, Soprano PM, Miguel-García C, Santos-Mínguez S, Serramito-Gómez I, Ruiz-Sala P, Peñarrubia MJ, Pardal E, Hernández-Rivas JM, González-Porras JR, García-Tuñón I, Benito R, Rivera J, Balduini A, Bastida JM. Novel variants in GALE cause syndromic macrothrombocytopenia by disrupting glycosylation and thrombopoiesis. Blood 2023; 141:406-421. [PMID: 36395340 PMCID: PMC10644051 DOI: 10.1182/blood.2022016995] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 11/07/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022] Open
Abstract
Glycosylation is recognized as a key process for proper megakaryopoiesis and platelet formation. The enzyme uridine diphosphate (UDP)-galactose-4-epimerase, encoded by GALE, is involved in galactose metabolism and protein glycosylation. Here, we studied 3 patients from 2 unrelated families who showed lifelong severe thrombocytopenia, bleeding diathesis, mental retardation, mitral valve prolapse, and jaundice. Whole-exome sequencing revealed 4 variants that affect GALE, 3 of those previously unreported (Pedigree A, p.Lys78ValfsX32 and p.Thr150Met; Pedigree B, p.Val128Met; and p.Leu223Pro). Platelet phenotype analysis showed giant and/or grey platelets, impaired platelet aggregation, and severely reduced alpha and dense granule secretion. Enzymatic activity of the UDP-galactose-4-epimerase enzyme was severely decreased in all patients. Immunoblotting of platelet lysates revealed reduced GALE protein levels, a significant decrease in N-acetyl-lactosamine (LacNAc), showing a hypoglycosylation pattern, reduced surface expression of gylcoprotein Ibα-IX-V (GPIbα-IX-V) complex and mature β1 integrin, and increased apoptosis. In vitro studies performed with patients-derived megakaryocytes showed normal ploidy and maturation but decreased proplatelet formation because of the impaired glycosylation of the GPIbα and β1 integrin, and reduced externalization to megakaryocyte and platelet membranes. Altered distribution of filamin A and actin and delocalization of the von Willebrand factor were also shown. Overall, this study expands our knowledge of GALE-related thrombocytopenia and emphasizes the critical role of GALE in the physiological glycosylation of key proteins involved in platelet production and function.
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Affiliation(s)
- Ana Marín-Quílez
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | | | - Lorena Díaz-Ajenjo
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - Vittorio Abbonante
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- Department of Health Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Elena Vuelta
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | | | - Cristina Miguel-García
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - Sandra Santos-Mínguez
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - Inmaculada Serramito-Gómez
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - Pedro Ruiz-Sala
- Centro de Diagnóstico de Enfermedades Moleculares, Universidad Autónoma de Madrid, CIBERER, IdIPAZ, Madrid, Spain
| | - María Jesús Peñarrubia
- Servicio de Hematología, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
| | - Emilia Pardal
- Servicio de Hematología, Hospital Virgen del Puerto, Plasencia, Spain
| | - Jesús María Hernández-Rivas
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
- Servicio de Hematología, Complejo Asistencial Universitario de Salamanca (CAUSA), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca (USAL), Salamanca, Spain
| | - José Ramón González-Porras
- Servicio de Hematología, Complejo Asistencial Universitario de Salamanca (CAUSA), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca (USAL), Salamanca, Spain
| | - Ignacio García-Tuñón
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
- Departamento de Biomedicina y Biotecnología, Universidad de Alcalá, Alcalá de Henares, Spain
| | - Rocío Benito
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Centro de Investigación del Cáncer (CIC), Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-Centro Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - José Rivera
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB)-Pascual Parrilla, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Murcia, Spain
| | - Alessandra Balduini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - José María Bastida
- Servicio de Hematología, Complejo Asistencial Universitario de Salamanca (CAUSA), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca (USAL), Salamanca, Spain
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4
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Derks B, Demirbas D, Arantes RR, Banford S, Burlina AB, Cabrera A, Chiesa A, Couce ML, Dionisi-Vici C, Gautschi M, Grünewald S, Morava E, Möslinger D, Scholl-Bürgi S, Skouma A, Stepien KM, Timson DJ, Berry GT, Rubio-Gozalbo ME. Galactose epimerase deficiency: lessons from the GalNet registry. Orphanet J Rare Dis 2022; 17:331. [PMID: 36056436 PMCID: PMC9438182 DOI: 10.1186/s13023-022-02494-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/15/2022] [Indexed: 11/29/2022] Open
Abstract
Background Galactose epimerase (GALE) deficiency is a rare hereditary disorder of galactose metabolism with only a few cases described in the literature. This study aims to present the data of patients with GALE deficiency from different countries included through the Galactosemia Network to further expand the existing knowledge and review the current diagnostic strategy, treatment and follow-up of this not well characterized entity.
Methods Observational study collecting medical data from December 2014 to April 2022 of 22 not previously reported patients from 14 centers in 9 countries. Patients were classified as generalized or non-generalized based on their genotype, enzyme activities in different tissues and/or clinical picture and professional judgment of the treating physician.
Results In total 6 patients were classified as generalized and 16 as non-generalized. In the generalized group, acute neonatal illness was reported in 3, cognitive and developmental delays were present in 5 and hearing problems were reported in 3. Four generalized patients were homozygous for the genetic variant NM_001008216.2:c.280G > A (p.Val94Met). In the non-generalized group, no clearly related symptoms were found. Ten novel genetic variants were reported in this study population.
Conclusion The phenotypic spectrum of GALE deficiency ranges from asymptomatic to severe. The generalized patients have a phenotype that is in line with the 9 described cases in the literature and prescribing dietary interventions is the cornerstone for treatment. In the non-generalized group, treatment advice is more difficult. To be able to offer proper counseling, in addition to red blood cell enzyme activity, genetic studies, transferrin glycoform analysis and enzymatic measurements in fibroblasts are recommended. Due to lack of facilities, additional enzymatic testing is not common practice in many centers nor a tailored long-term follow-up is performed. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02494-4.
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Affiliation(s)
- Britt Derks
- Department of Pediatrics and Clinical Genetics, Maastricht University Medical Centre+, P. Debyelaan 25, P.O. Box 5800, 6229 HX, Maastricht, The Netherlands.,GROW, Maastricht University, Maastricht, The Netherlands.,MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy.,UMD: United for Metabolic Diseases Member, Amsterdam, The Netherlands
| | - Didem Demirbas
- Division of Genetics and Genomics, Harvard Medical School, Boston Children's Hospital, 3 Blackfan Circle, Center for Life Science Building, Suite 14070, Boston, MA, 02115, USA
| | - Rodrigo R Arantes
- Special Service of Medical Genetics, Hospital das Clínicas da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Samantha Banford
- South Eastern Health and Social Care Trust, Downpatrick, BT30 6RL, UK
| | - Alberto B Burlina
- MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy.,Division of Inherited Metabolic Diseases, University Hospital, Via Orus 2/B, 35128, Padua, Italy
| | - Analía Cabrera
- Nutrition Department, Hospital de Niños V.J. Vilela, Sante Fe, Rosario, Argentina
| | - Ana Chiesa
- Department of Endocrinology, Hospital de Niños Ricardo Gutièrrez, Buenos Aires, Argentina
| | - M Luz Couce
- MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy.,Metabolic Unit, IDIS, Department of Neonatology, University Clinical Hospital of Santiago de Compostela. Calle Choupana, s/n, 15706, Santiago de Compostela, Spain
| | - Carlo Dionisi-Vici
- MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy.,Division of Metabolism, Bambino Gesu Children's Research Hospital IRCCS, Piazza S Onofrio 4, 00165, Roma, Italy
| | - Matthias Gautschi
- Division of Paediatric Endocrinology and Metabolism, Department of Paediatrics, University Hospital Bern, Inselspital, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Stephanie Grünewald
- Metabolic Medicine Department, NIHR Biomedical Research Center (BRC), Institute for Child Health, Great Ormond Street Hospital, University College London, London, UK
| | - Eva Morava
- Department of Clinical Genomics and Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Dorothea Möslinger
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Sabine Scholl-Bürgi
- MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy.,Clinic for Pediatrics I, Inherited Metabolic Disorders, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Anastasia Skouma
- Institute of Child Health, Aghia Sophia Children's Hospital, Thivon & Papadiamantopoulou, 11527, Athens, Greece
| | - Karolina M Stepien
- Adult Inherited Metabolic Disorders Department, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, Greater Manchester, UK
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, UK
| | - Gerard T Berry
- Division of Genetics and Genomics, Harvard Medical School, Boston Children's Hospital, 3 Blackfan Circle, Center for Life Science Building, Suite 14070, Boston, MA, 02115, USA
| | - M Estela Rubio-Gozalbo
- Department of Pediatrics and Clinical Genetics, Maastricht University Medical Centre+, P. Debyelaan 25, P.O. Box 5800, 6229 HX, Maastricht, The Netherlands. .,GROW, Maastricht University, Maastricht, The Netherlands. .,MetabERN: European Reference Network for Hereditary Metabolic Disorders, Udine, Italy. .,UMD: United for Metabolic Diseases Member, Amsterdam, The Netherlands.
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5
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Kumar SU, Sankar S, Kumar DT, Younes S, Younes N, Siva R, Doss CGP, Zayed H. Molecular dynamics, residue network analysis, and cross-correlation matrix to characterize the deleterious missense mutations in GALE causing galactosemia III. Cell Biochem Biophys 2021; 79:201-219. [PMID: 33555556 DOI: 10.1007/s12013-020-00960-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2020] [Indexed: 01/17/2023]
Abstract
Epimerase-deficiency galactosemia (EDG) is caused by mutations in the UDP-galactose 4'-epimerase enzyme, encoded by gene GALE. Catalyzing the last reaction in the Leloir pathway, UDP-galactose-4-epimerase catalyzes the interconversion of UDP-galactose and UDP-glucose. This study aimed to use in-depth computational strategies to prioritize the pathogenic missense mutations in GALE protein and investigate the systemic behavior, conformational spaces, atomic motions, and cross-correlation matrix of the GALE protein. We searched four databases (dbSNP, ClinVar, UniProt, and HGMD) and major biological literature databases (PubMed, Science Direct, and Google Scholar), for missense mutations that are associated with EDG patients, our search yielded 190 missense mutations. We applied a systematic computational prediction pipeline, including pathogenicity, stability, biochemical, conservational, protein residue contacts, and structural analysis, to predict the pathogenicity of these mutations. We found three mutations (p.K161N, p.R239W, and p.G302D) with a severe phenotype in patients with EDG that correlated with our computational prediction analysis; thus, they were selected for further structural and simulation analyses to compute the flexibility and stability of the mutant GALE proteins. The three mutants were subjected to molecular dynamics simulation (MDS) with native protein for 200 ns using GROMACS. The MDS demonstrated that these mutations affected the beta-sheets and helical region that are responsible for the catalytic activity; subsequently, affects the stability and flexibility of the mutant proteins along with a decrease and more deviations in compactness when compared to that of a native. Also, three mutations created major variations in the combined atomic motions of the catalytic and C-terminal regions. The network analysis of the residues in the native and three mutant protein structures showed disturbed residue contacts occurred owing to the missense mutations. Our findings help to understand the structural behavior of a protein owing to mutation and are intended to serve as a platform for prioritizing mutations, which could be potential targets for drug discovery and development of targeted therapeutics.
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Affiliation(s)
- S Udhaya Kumar
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - Srivarshini Sankar
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - D Thirumal Kumar
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - Salma Younes
- Department of Biomedical Sciences, College of Health and Sciences, Qatar University, QU Health, Doha, Qatar
| | - Nadin Younes
- Department of Biomedical Sciences, College of Health and Sciences, Qatar University, QU Health, Doha, Qatar
| | - R Siva
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - C George Priya Doss
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India.
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health and Sciences, Qatar University, QU Health, Doha, Qatar.
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6
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Banford S, McCorvie TJ, Pey AL, Timson DJ. Galactosemia: Towards Pharmacological Chaperones. J Pers Med 2021; 11:jpm11020106. [PMID: 33562227 PMCID: PMC7914515 DOI: 10.3390/jpm11020106] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/07/2023] Open
Abstract
Galactosemia is a rare inherited metabolic disease resulting from mutations in the four genes which encode enzymes involved in the metabolism of galactose. The current therapy, the removal of galactose from the diet, is inadequate. Consequently, many patients suffer lifelong physical and cognitive disability. The phenotype varies from almost asymptomatic to life-threatening disability. The fundamental biochemical cause of the disease is a decrease in enzymatic activity due to failure of the affected protein to fold and/or function correctly. Many novel therapies have been proposed for the treatment of galactosemia. Often, these are designed to treat the symptoms and not the fundamental cause. Pharmacological chaperones (PC) (small molecules which correct the folding of misfolded proteins) represent an exciting potential therapy for galactosemia. In theory, they would restore enzyme function, thus preventing downstream pathological consequences. In practice, no PCs have been identified for potential application in galactosemia. Here, we review the biochemical basis of the disease, identify opportunities for the application of PCs and describe how these might be discovered. We will conclude by considering some of the clinical issues which will affect the future use of PCs in the treatment of galactosemia.
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Affiliation(s)
- Samantha Banford
- South Eastern Health and Social Care Trust, Downpatrick BT30 6RL, UK;
| | - Thomas J. McCorvie
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK;
| | - Angel L. Pey
- Departamento de Química Física, Unidad de Excelencia de Química aplicada a Biomedicina y Medioambiente e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain;
| | - David J. Timson
- School of Pharmacy and Biomolecular Sciences, The University of Brighton, Brighton BN2 4GJ, UK
- Correspondence:
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7
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Thomas CM, Timson DJ. The Schistosoma mansoni tegumental allergen protein, SmTAL1: Binding to an IQ-motif from a voltage-gated ion channel and effects of praziquantel. Cell Calcium 2020; 86:102161. [PMID: 31981914 DOI: 10.1016/j.ceca.2020.102161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 12/30/2019] [Accepted: 01/10/2020] [Indexed: 11/28/2022]
Abstract
SmTAL1 is a calcium binding protein from the parasitic worm, Schistosoma mansoni. Structurally it is comprised of two domains - an N-terminal EF-hand domain and a C-terminal dynein light chain (DLC)-like domain. The protein has previously been shown to interact with the anti-schistosomal drug, praziquantel (PZQ). Here, we demonstrated that both EF-hands in the N-terminal domain are functional calcium ion binding sites. The second EF-hand appears to be more important in dictating affinity and mediating the conformational changes which occur on calcium ion binding. There is positive cooperativity between the four calcium ion binding sites in the dimeric form of SmTAL1. Both the EF-hand domain and the DLC-domain dimerise independently suggesting that both play a role in forming the SmTAL1 dimer. SmTAL1 binds non-cooperatively to PZQ and cooperatively to an IQ-motif from SmCav1B, a voltage-gated calcium channel. PZQ tends to strengthen this interaction, although the relationship is complex. These data suggest the hypothesis that SmTAL1 regulates at least one voltage-gated calcium channel and PZQ interferes with this process. This may be important in the molecular mechanism of this drug. It also suggests that compounds which bind SmTAL1, such as six from the Medicines for Malaria Box identified in this work, may represent possible leads for the discovery of novel antagonists.
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Affiliation(s)
- Charlotte M Thomas
- School of Biological Sciences and Institute for Global Food Security, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, UK.
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8
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Sun X, Xue H, Xiong Y, Yu R, Gao X, Qian M, Wang S, Wang H, Xu J, Chen Z, Deng L, Li G. GALE Promotes the Proliferation and Migration of Glioblastoma Cells and Is Regulated by miR-let-7i-5p. Cancer Manag Res 2019; 11:10539-10554. [PMID: 31908526 PMCID: PMC6924591 DOI: 10.2147/cmar.s221585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/16/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose Glioma is the most common and lethal type of brain tumor. While GALE (UDP-galactose-4-epimerase) has been shown to be overexpressed in some kinds of cancers, its expression in gliomas has not been reported. MicroRNAs (miRNAs) function as tumor suppressors in many cancers, and online datasets can be used to predict whether GALE is regulated by miR-let-7i-5p. In this investigation, we explored the effect and regulatory mechanisms of GALE on glioblastoma growth via miR-let-7i-5p. Methods We used a Cox proportional hazards model and publicly available datasets to examine the relationship between GALE and the survival rates of glioma patients. Bioinformatics predicted the targeting of GALE by miR-let-7i-5p. The proliferation, migration, cell cycle and apoptosis of human glioblastoma cells were assessed by relevant assays. We also demonstrated the effect of GALE on glioblastoma multiforme [GBM] tumor growth using an in vivo orthotopic xenograft model. Results GALE was upregulated in human gliomas, especially in high-grade gliomas (e.g., GBM). An obvious decline in GALE expression was observed in human glioblastoma cell lines (U87 and U251) following treatment with a small interfering RNA (siRNA) targeting GALE or miR-let-7i-5p mimics. Knockdown of GALE or overexpression of miR-let-7i-5p (with miR-let-7i-5p mimics) inhibited U87 and U251 cell growth. miR-let-7i-5p significantly restrained the migration ability of human glioblastoma cells in vascular mimic (VM), wound healing and transwell assays, and GALE promoted glioblastoma growth in vivo. Conclusion Our findings confirm that GALE plays an important role in promoting the development of human glioma and that GALE can be regulated by miR-let-7i-5p to inhibit human glioblastoma growth. Implications for cancer survivors Our data show that cancer survivors have low GALE expression, which indicates that GALE may be a diagnostic biomarker and a promising therapeutic target in glioblastoma.
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Affiliation(s)
- Xiaopeng Sun
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China.,Department of Neurosurgery, Dezhou People's Hospital, Dezhou, Shandong Province 253014, People's Republic of China
| | - Hao Xue
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China.,Institute of Brain and Brain-Inspired Science, Shandong Provincial Key Laboratory of Brain Function Remodeling, Shandong University, Jinan, Shandong Province, People's Republic of China
| | - Ye Xiong
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325000, People's Republic of China
| | - Rui Yu
- Department of Neurosurgery, The Second Hospital of Shandong University, Jinan 250033, People's Republic of China
| | - Xiao Gao
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Mingyu Qian
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Shaobo Wang
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Huizhi Wang
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Jianye Xu
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Zihang Chen
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China
| | - Lin Deng
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China.,Institute of Brain and Brain-Inspired Science, Shandong Provincial Key Laboratory of Brain Function Remodeling, Shandong University, Jinan, Shandong Province, People's Republic of China
| | - Gang Li
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, People's Republic of China.,Institute of Brain and Brain-Inspired Science, Shandong Provincial Key Laboratory of Brain Function Remodeling, Shandong University, Jinan, Shandong Province, People's Republic of China
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9
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Overexpression of UDP-Glucose 4-Epimerase Is Associated with Differentiation Grade of Gastric Cancer. DISEASE MARKERS 2019; 2019:6325326. [PMID: 31827638 PMCID: PMC6886318 DOI: 10.1155/2019/6325326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 10/08/2019] [Accepted: 11/02/2019] [Indexed: 11/20/2022]
Abstract
The UDP-glucose 4-epimerase (GALE) is a glycosyltransferase, which acts on protein and lipid glycosylation in normal and neoplastic cells. This study is aimed at investigating the differential tissue expression of GALE and its possible association with clinical-pathological parameters and the outcome of gastric adenocarcinoma patients. Seventy-one patients were evaluated in relation to GALE expression by immunohistochemistry. Our results showed that 48 (67.6%) patients were GALE positive and 23 (32.4%) negative. Positive staining was present on well-differentiated and moderate-differentiated histological grade of gastric adenocarcinomas (p < 0.0001). There was no significant association with outcome parameters (p > 0.05). Besides that, our results corroborated with the validation cohort analysis, where the expression of GALE mRNA was also associated with the histological grade (p < 0.001). These results suggest a possible use of this enzyme as a biomarker for well and moderately differentiated tumors.
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10
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Seo A, Gulsuner S, Pierce S, Ben-Harosh M, Shalev H, Walsh T, Krasnov T, Dgany O, Doulatov S, Tamary H, Shimamura A, King MC. Inherited thrombocytopenia associated with mutation of UDP-galactose-4-epimerase (GALE). Hum Mol Genet 2019; 28:133-142. [PMID: 30247636 DOI: 10.1093/hmg/ddy334] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 09/07/2018] [Indexed: 12/11/2022] Open
Abstract
Severe thrombocytopenia, characterized by dysplastic megakaryocytes and intracranial bleeding, was diagnosed in six individuals from a consanguineous kindred. Three of the individuals were successfully treated by bone marrow transplant. Whole-exome sequencing and homozygosity mapping of multiple family members, coupled with whole-genome sequencing to reveal shared non-coding variants, revealed one potentially functional variant segregating with thrombocytopenia under a recessive model: GALE p.R51W (c.C151T, NM_001127621). The mutation is extremely rare (allele frequency = 2.5 × 10-05), and the likelihood of the observed co-segregation occurring by chance is 1.2 × 10-06. GALE encodes UDP-galactose-4-epimerase, an enzyme of galactose metabolism and glycosylation responsible for two reversible reactions: interconversion of UDP-galactose with UDP-glucose and interconversion of UDP-N-acetylgalactosamine with UDP-N-acetylglucosamine. The mutation alters an amino acid residue that is conserved from yeast to humans. The variant protein has both significantly lower enzymatic activity for both interconversion reactions and highly significant thermal instability. Proper glycosylation is critical to normal hematopoiesis, in particular to megakaryocyte and platelet development, as reflected in the presence of thrombocytopenia in the context of congenital disorders of glycosylation. Mutations in GALE have not previously been associated with thrombocytopenia. Our results suggest that GALE p.R51W is inadequate for normal glycosylation and thereby may impair megakaryocyte and platelet development. If other mutations in GALE are shown to have similar consequences, this gene may be proven to play a critical role in hematopoiesis.
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Affiliation(s)
- Aaron Seo
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Suleyman Gulsuner
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Sarah Pierce
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Miri Ben-Harosh
- Department of Pediatric Hematology/Oncology, Soroka Medical Center, Faculty of Medicine, Ben-Gurion University, Beer Sheva, Israel
| | - Hanna Shalev
- Department of Pediatric Hematology/Oncology, Soroka Medical Center, Faculty of Medicine, Ben-Gurion University, Beer Sheva, Israel
| | - Tom Walsh
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | - Tanya Krasnov
- Pediatric Hematology Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Orly Dgany
- Pediatric Hematology Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Sergei Doulatov
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, USA
| | - Hannah Tamary
- Pediatric Hematology Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.,Hematology Unit, Schneider Children's Medical Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Akiko Shimamura
- Department of Pediatric Hematology/Oncology, Boston Children's Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Mary-Claire King
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, USA
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11
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Shvarev D, Nishi CN, Maldener I. Glycolipid composition of the heterocyst envelope of Anabaena sp. PCC 7120 is crucial for diazotrophic growth and relies on the UDP-galactose 4-epimerase HgdA. Microbiologyopen 2019; 8:e00811. [PMID: 30803160 PMCID: PMC6692557 DOI: 10.1002/mbo3.811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 01/05/2023] Open
Abstract
The nitrogenase complex in the heterocysts of the filamentous freshwater cyanobacterium Anabaenasp. PCC 7120 fixes atmospheric nitrogen to allow diazotrophic growth. The heterocyst cell envelope protects the nitrogenase from oxygen and consists of a polysaccharide and a glycolipid layer that are formed by a complex process involving the recruitment of different proteins. Here, we studied the function of the putative nucleoside‐diphosphate‐sugar epimerase HgdA, which along with HgdB and HgdC is essential for deposition of the glycolipid layer and growth without a combined nitrogen source. Using site‐directed mutagenesis and single homologous recombination approach, we performed a thoroughly functional characterization of HgdA and confirmed that the glycolipid layer of the hgdAmutant heterocyst is aberrant as shown by transmission electron microscopy and chemical analysis. The hgdA gene was expressed during late stages of the heterocyst differentiation. GFP‐tagged HgdA protein localized inside the heterocysts. The purified HgdA protein had UDP‐galactose 4‐epimerase activity in vitro. This enzyme could be responsible for synthesis of heterocyst‐specific glycolipid precursors, which could be transported over the cell wall by the ABC transporter components HgdB/HgdC.
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Affiliation(s)
- Dmitry Shvarev
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Carolina N Nishi
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Iris Maldener
- Organismic Interactions, Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls University of Tübingen, Tübingen, Germany
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12
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Timson DJ. The molecular basis of galactosemia — Past, present and future. Gene 2016; 589:133-41. [DOI: 10.1016/j.gene.2015.06.077] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/18/2015] [Accepted: 06/29/2015] [Indexed: 12/19/2022]
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13
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Drozdova PB, Tarasov OV, Matveenko AG, Radchenko EA, Sopova JV, Polev DE, Inge-Vechtomov SG, Dobrynin PV. Genome Sequencing and Comparative Analysis of Saccharomyces cerevisiae Strains of the Peterhof Genetic Collection. PLoS One 2016; 11:e0154722. [PMID: 27152522 PMCID: PMC4859572 DOI: 10.1371/journal.pone.0154722] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/18/2016] [Indexed: 01/09/2023] Open
Abstract
The Peterhof genetic collection of Saccharomyces cerevisiae strains (PGC) is a large laboratory stock that has accumulated several thousands of strains for over than half a century. It originated independently of other common laboratory stocks from a distillery lineage (race XII). Several PGC strains have been extensively used in certain fields of yeast research but their genomes have not been thoroughly explored yet. Here we employed whole genome sequencing to characterize five selected PGC strains including one of the closest to the progenitor, 15V-P4, and several strains that have been used to study translation termination and prions in yeast (25-25-2V-P3982, 1B-D1606, 74-D694, and 6P-33G-D373). The genetic distance between the PGC progenitor and S288C is comparable to that between two geographically isolated populations. The PGC seems to be closer to two bakery strains than to S288C-related laboratory stocks or European wine strains. In genomes of the PGC strains, we found several loci which are absent from the S288C genome; 15V-P4 harbors a rare combination of the gene cluster characteristic for wine strains and the RTM1 cluster. We closely examined known and previously uncharacterized gene variants of particular strains and were able to establish the molecular basis for known phenotypes including phenylalanine auxotrophy, clumping behavior and galactose utilization. Finally, we made sequencing data and results of the analysis available for the yeast community. Our data widen the knowledge about genetic variation between Saccharomyces cerevisiae strains and can form the basis for planning future work in PGC-related strains and with PGC-derived alleles.
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Affiliation(s)
- Polina B. Drozdova
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- Bioinformatics Institute, St. Petersburg, Russia
| | - Oleg V. Tarasov
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- St. Petersburg Scientific Center of RAS, St. Petersburg, Russia
| | - Andrew G. Matveenko
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- St. Petersburg Branch, Vavilov Institute of General Genetics of the Russian Academy of Sciences, St. Petersburg, Russia
- Laboratory of Amyloid Biology, Saint Petersburg State University, St. Petersburg, Russia
| | - Elina A. Radchenko
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- Bioinformatics Institute, St. Petersburg, Russia
| | - Julia V. Sopova
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- St. Petersburg Branch, Vavilov Institute of General Genetics of the Russian Academy of Sciences, St. Petersburg, Russia
- Institute of Translational Biomedicine, Saint Petersburg State University, St. Petersburg, Russia
| | - Dmitrii E. Polev
- Research Resource Center for Molecular and Cell Technologies, Research Park, Saint-Petersburg State University, St. Petersburg, Russia
| | - Sergey G. Inge-Vechtomov
- Dept. of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russia
- St. Petersburg Branch, Vavilov Institute of General Genetics of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Pavel V. Dobrynin
- Bioinformatics Institute, St. Petersburg, Russia
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, St. Petersburg, Russia
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14
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Paul S, McCorvie TJ, Zschocke J, Timson DJ. Disturbed cofactor binding by a novel mutation in UDP-galactose 4′-epimerase results in a type III galactosemia phenotype at birth. RSC Adv 2016. [DOI: 10.1039/c6ra00306k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The p.A89V variant of UDP-galactose 4′-epimerase (GALE) is less stable and has lower affinity for the NAD+cofactor than the wild-type enzyme.
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Affiliation(s)
- Stephanie Paul
- School of Biological Sciences
- Queen's University Belfast
- Medical Biology Centre
- Belfast
- UK
| | - Thomas J. McCorvie
- School of Biological Sciences
- Queen's University Belfast
- Medical Biology Centre
- Belfast
- UK
| | - Johannes Zschocke
- Division of Human Genetics
- Innsbruck Medical University
- Innsbruck 6020
- Austria
| | - David J. Timson
- School of Biological Sciences
- Queen's University Belfast
- Medical Biology Centre
- Belfast
- UK
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15
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Fuchs JE, Muñoz IG, Timson DJ, Pey AL. Experimental and computational evidence on conformational fluctuations as a source of catalytic defects in genetic diseases. RSC Adv 2016. [DOI: 10.1039/c6ra05499d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Catalytic mutants causing inherited type III galactosemia alter active site structural dynamics and shift the native conformational equilibrium towards inactive conformations.
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Affiliation(s)
- Julian E. Fuchs
- Institute of General, Inorganic and Theoretical Chemistry
- Faculty of Chemistry and Pharmacy
- University of Innsbruck
- Innsbruck
- Austria
| | - Inés G. Muñoz
- Crystallography and Protein Engineering Unit
- Structural Biology and Biocomputing Programme
- Spanish National Cancer Research Centre (CNIO)
- Madrid
- Spain
| | - David J. Timson
- School of Pharmacy and Biomolecular Sciences
- The University of Brighton
- Brighton
- UK
| | - Angel L. Pey
- Department of Physical Chemistry
- Faculty of Sciences
- University of Granada
- Granada
- Spain
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16
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FhCaBP2: a Fasciola hepatica calcium-binding protein with EF-hand and dynein light chain domains. Parasitology 2015; 142:1375-86. [DOI: 10.1017/s0031182015000736] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
SUMMARYFhCaBP2 is a Fasciola hepatica protein which belongs to a family of helminth calcium-binding proteins which combine an N-terminal domain containing two EF-hand motifs and a C-terminal dynein light chain-like (DLC-like) domain. Its predicted structure showed two globular domains joined by a flexible linker. Recombinant FhCaBP2 interacted reversibly with calcium and manganese ions, but not with magnesium, barium, strontium, copper (II), colbalt (II), iron (II), nickel, lead or potassium ions. Cadmium (II) ions appeared to bind non-site-specifically and destabilize the protein. Interaction with either calcium or magnesium ions results in a conformational change in which the protein's surface becomes more hydrophobic. The EF-hand domain alone was able to interact with calcium and manganese ions; the DLC-like domain was not. Alteration of a residue (Asp-58 to Ala) in the second EF-hand motif in this domain abolished ion-binding activity. This suggests that the second EF-hand is the one responsible for ion-binding. FhCaBP2 homodimerizes and the extent of dimerization was not affected by calcium ions or by the aspartate to alanine substitution in the second EF-hand. The isolated EF-hand and DLC-like domains are both capable of homodimerization. FhCaBP2 interacted with the calmodulin antagonists trifluoperazine, chlorpromazine, thiamylal and W7. Interestingly, while chlorpromazine and thiamylal interacted with the EF-hand domain (as expected), trifluoperazine and W7 bound to the DLC-like domain. Overall, FhCaBP2 has distinct biochemical properties compared with other members of this protein family from Fasciola hepatica, a fact which supports the hypothesis that these proteins have different physiological roles.
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17
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The critical role of UDP-galactose-4-epimerase in osteoarthritis: Modulating proteoglycans synthesis of the articular chondrocytes. Biochem Biophys Res Commun 2014; 452:906-11. [DOI: 10.1016/j.bbrc.2014.08.148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 08/28/2014] [Indexed: 11/22/2022]
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18
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Pey AL, Padín-Gonzalez E, Mesa-Torres N, Timson DJ. The metastability of human UDP-galactose 4'-epimerase (GALE) is increased by variants associated with type III galactosemia but decreased by substrate and cofactor binding. Arch Biochem Biophys 2014; 562:103-14. [PMID: 25150110 DOI: 10.1016/j.abb.2014.07.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 07/22/2014] [Accepted: 07/23/2014] [Indexed: 01/30/2023]
Abstract
Type III galactosemia is an inherited disease caused by mutations which affect the activity of UDP-galactose 4'-epimerase (GALE). We evaluated the impact of four disease-associated variants (p.N34S, p.G90E, p.V94M and p.K161N) on the conformational stability and dynamics of GALE. Thermal denaturation studies showed that wild-type GALE denatures at temperatures close to physiological, and disease-associated mutations often reduce GALE's thermal stability. This denaturation is under kinetic control and results partly from dimer dissociation. The natural ligands, NAD(+) and UDP-glucose, stabilize GALE. Proteolysis studies showed that the natural ligands and disease-associated variations affect local dynamics in the N-terminal region of GALE. Proteolysis kinetics followed a two-step irreversible model in which the intact protein is cleaved at Ala38 forming a long-lived intermediate in the first step. NAD(+) reduces the rate of the first step, increasing the amount of undigested protein whereas UDP-glucose reduces the rate of the second step, increasing accumulation of the intermediate. Disease-associated variants affect these rates and the amounts of protein in each state. Our results also suggest communication between domains in GALE. We hypothesize that, in vivo, concentrations of natural ligands modulate GALE stability and that it should be possible to discover compounds which mimic the stabilising effects of the natural ligands overcoming mutation-induced destabilization.
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Affiliation(s)
- Angel L Pey
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, 18071, Spain.
| | - Esperanza Padín-Gonzalez
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, 18071, Spain
| | - Noel Mesa-Torres
- Department of Physical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, 18071, Spain
| | - David J Timson
- School of Biological Sciences, Queeńs University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK.
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19
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UDP-galactose 4'-epimerase from the liver fluke, Fasciola hepatica: biochemical characterization of the enzyme and identification of inhibitors. Parasitology 2014; 142:463-72. [PMID: 25124392 DOI: 10.1017/s003118201400136x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Leloir pathway enzyme uridine diphosphate (UDP)-galactose 4'-epimerase from the common liver fluke Fasciola hepatica (FhGALE) was identified and characterized. The enzyme can be expressed in, and purified from, Escherichia coli. The recombinant enzyme is active: the K(m) (470 μM) is higher than the corresponding human enzyme (HsGALE), whereas the k(cat) (2.3 s(-1)) is substantially lower. FhGALE binds NAD(+) and has shown to be dimeric by analytical gel filtration. Like the human and yeast GALEs, FhGALE is stabilized by the substrate UDP-galactose. Molecular modelling predicted that FhGALE adopts a similar overall fold to HsGALE and that tyrosine 155 is likely to be the catalytically critical residue in the active site. In silico screening of the National Cancer Institute Developmental Therapeutics Program library identified 40 potential inhibitors of FhGALE which were tested in vitro. Of these, 6 showed concentration-dependent inhibition of FhGALE, some with nanomolar IC50 values. Two inhibitors (5-fluoroorotate and N-[(benzyloxy)carbonyl]leucyltryptophan) demonstrated selectivity for FhGALE over HsGALE. These compounds also thermally destabilized FhGALE in a concentration-dependent manner. Interestingly, the selectivity of 5-fluoroorotate was not shown by orotic acid, which differs in structure by 1 fluorine atom. These results demonstrate that, despite the structural and biochemical similarities of FhGALE and HsGALE, it is possible to discover compounds which preferentially inhibit FhGALE.
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20
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Zinsser VL, Hoey EM, Trudgett A, Timson DJ. Biochemical characterisation of triose phosphate isomerase from the liver fluke Fasciola hepatica. Biochimie 2013; 95:2182-9. [DOI: 10.1016/j.biochi.2013.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 08/07/2013] [Indexed: 11/29/2022]
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21
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Dalrymple SA, Ko J, Sheoran I, Kaminskyj SGW, Sanders DAR. Elucidation of substrate specificity in Aspergillus nidulans UDP-galactose-4-epimerase. PLoS One 2013; 8:e76803. [PMID: 24116166 PMCID: PMC3792076 DOI: 10.1371/journal.pone.0076803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/27/2013] [Indexed: 11/18/2022] Open
Abstract
The frequency of invasive fungal infections has rapidly increased in recent years. Current clinical treatments are experiencing decreased potency due to severe host toxicity and the emergence of fungal drug resistance. As such, new targets and their corresponding synthetic pathways need to be explored for drug development purposes. In this context, galactofuranose residues, which are employed in fungal cell wall construction, but are notably absent in animals, represent an appealing target. Herein we present the structural and biochemical characterization of UDP-galactose-4-epimerase from Aspergillus nidulans which produces the precursor UDP-galactopyranose required for galactofuranose synthesis. Examination of the structural model revealed both NAD+ and UDP-glucopyranose were bound within the active site cleft in a near identical fashion to that found in the Human epimerase. Mutational studies on the conserved catalytic motif support a similar mechanism to that established for the Human counterpart is likely operational within the A. nidulans epimerase. While the Km and kcat for the enzyme were determined to be 0.11 mM and 12.8 s-1, respectively, a single point mutation, namely L320C, activated the enzyme towards larger N-acetylated substrates. Docking studies designed to probe active site affinity corroborate the experimentally determined activity profiles and support the kinetic inhibition results.
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Affiliation(s)
- Sean A. Dalrymple
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - John Ko
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Inder Sheoran
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - David A. R. Sanders
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- * E-mail:
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22
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Timson DJ, Lindert S. Comparison of dynamics of wildtype and V94M human UDP-galactose 4-epimerase-A computational perspective on severe epimerase-deficiency galactosemia. Gene 2013; 526:318-24. [PMID: 23732289 DOI: 10.1016/j.gene.2013.05.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/11/2013] [Accepted: 05/21/2013] [Indexed: 11/25/2022]
Abstract
UDP-galactose 4'-epimerase (GALE) catalyzes the interconversion of UDP-galactose and UDP-glucose, an important step in galactose catabolism. Type III galactosemia, an inherited metabolic disease, is associated with mutations in human GALE. The V94M mutation has been associated with a very severe form of type III galactosemia. While a variety of structural and biochemical studies have been reported that elucidate differences between the wildtype and this mutant form of human GALE, little is known about the dynamics of the protein and how mutations influence structure and function. We performed molecular dynamics simulations on the wildtype and V94M enzyme in different states of substrate and cofactor binding. In the mutant, the average distance between the substrate and both a key catalytic residue (Tyr157) and the enzyme-bound NAD+ cofactor and the active site dynamics are altered making substrate binding slightly less stable. However, overall stability or dynamics of the protein is not altered. This is consistent with experimental findings that the impact is largely on the turnover number (kcat), with less substantial effects on Km. Active site fluctuations were found to be correlated in enzyme with substrate bound to just one of the subunits in the homodimer suggesting inter-subunit communication. Greater active site loop mobility in human GALE compared to the equivalent loop in Escherichia coli GALE explains why the former can catalyze the interconversion of UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine while the bacterial enzyme cannot. This work illuminates molecular mechanisms of disease and may inform the design of small molecule therapies for type III galactosemia.
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Affiliation(s)
- David J Timson
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
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McCorvie TJ, Timson DJ. In silico prediction of the effects of mutations in the human UDP-galactose 4'-epimerase gene: towards a predictive framework for type III galactosemia. Gene 2013; 524:95-104. [PMID: 23644136 DOI: 10.1016/j.gene.2013.04.061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/30/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
Abstract
The enzyme UDP-galactose 4'-epimerase (GALE) catalyses the reversible epimerisation of both UDP-galactose and UDP-N-acetyl-galactosamine. Deficiency of the human enzyme (hGALE) is associated with type III galactosemia. The majority of known mutations in hGALE are missense and private thus making clinical guidance difficult. In this study a bioinformatics approach was employed to analyse the structural effects due to each mutation using both the UDP-glucose and UDP-N-acetylglucosamine bound structures of the wild-type protein. Changes to the enzyme's overall stability, substrate/cofactor binding and propensity to aggregate were also predicted. These predictions were found to be in good agreement with previous in vitro and in vivo studies when data was available and allowed for the differentiation of those mutants that severely impair the enzyme's activity against UDP-galactose. Next this combination of techniques were applied to another twenty-six reported variants from the NCBI dbSNP database that have yet to be studied to predict their effects. This identified p.I14T, p.R184H and p.G302R as likely severely impairing mutations. Although severely impaired mutants were predicted to decrease the protein's stability, overall predicted stability changes only weakly correlated with residual activity against UDP-galactose. This suggests other protein functions such as changes in cofactor and substrate binding may also contribute to the mechanism of impairment. Finally this investigation shows that this combination of different in silico approaches is useful in predicting the effects of mutations and that it could be the basis of an initial prediction of likely clinical severity when new hGALE mutants are discovered.
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Affiliation(s)
- Thomas J McCorvie
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
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24
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Wu X, Vellaichamy A, Wang D, Zamdborg L, Kelleher NL, Huber SC, Zhao Y. Differential lysine acetylation profiles of Erwinia amylovora strains revealed by proteomics. J Proteomics 2012; 79:60-71. [PMID: 23234799 DOI: 10.1016/j.jprot.2012.12.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/05/2012] [Accepted: 12/01/2012] [Indexed: 01/01/2023]
Abstract
Protein lysine acetylation (LysAc) has recently been demonstrated to be widespread in E. coli and Salmonella, and to broadly regulate bacterial physiology and metabolism. However, LysAc in plant pathogenic bacteria is largely unknown. Here we first report the lysine acetylome of Erwinia amylovora, an enterobacterium causing serious fire blight disease of apples and pears. Immunoblots using generic anti-lysine acetylation antibodies demonstrated that growth conditions strongly affected the LysAc profiles in E. amylovora. Differential LysAc profiles were also observed for two E. amylovora strains, known to have differential virulence in plants, indicating translational modification of proteins may be important in determining virulence of bacterial strains. Proteomic analysis of LysAc in two E. amylovora strains identified 141 LysAc sites in 96 proteins that function in a wide range of biological pathways. Consistent with previous reports, 44% of the proteins are involved in metabolic processes, including central metabolism, lipopolysaccharide, nucleotide and amino acid metabolism. Interestingly, for the first time, several proteins involved in E. amylovora virulence, including exopolysaccharide amylovoran biosynthesis- and type III secretion-associated proteins, were found to be lysine acetylated, suggesting that LysAc may play a major role in bacterial virulence. Comparative analysis of LysAc sites in E. amylovora and E. coli further revealed the sequence and structural commonality for LysAc in the two organisms. Collectively, these results reinforce the notion that LysAc of proteins is widespread in bacterial metabolism and virulence.
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Affiliation(s)
- Xia Wu
- Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA
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25
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Andrews WJ, Bradley CA, Hamilton E, Daly C, Mallon T, Timson DJ. A calcium-dependent interaction between calmodulin and the calponin homology domain of human IQGAP1. Mol Cell Biochem 2012; 371:217-23. [PMID: 22944912 DOI: 10.1007/s11010-012-1438-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/25/2012] [Indexed: 01/01/2023]
Abstract
IQGAPs are cytoskeletal scaffolding proteins which collect information from a variety of signalling pathways and pass it on to the microfilaments and microtubules. There is a well-characterised interaction between IQGAP and calmodulin through a series of IQ-motifs towards the middle of the primary sequence. However, it has been shown previously that the calponin homology domain (CHD), located at the N-terminus of the protein, can also interact weakly with calmodulin. Using a recombinant fragment of human IQGAP1 which encompasses the CHD, we have demonstrated that the CHD undergoes a calcium ion-dependent interaction with calmodulin. The CHD can also displace the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulphonate from calcium-calmodulin, suggesting that the interaction involves non-polar residues on the surface of calmodulin. Molecular modelling identified a possible site on the CHD for calmodulin interaction. The physiological significance of this interaction remains to be discovered.
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Affiliation(s)
- William J Andrews
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
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26
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Friedman AJ, Durrant JD, Pierce LCT, McCorvie TJ, Timson DJ, McCammon JA. The molecular dynamics of Trypanosoma brucei UDP-galactose 4'-epimerase: a drug target for African sleeping sickness. Chem Biol Drug Des 2012; 80:173-81. [PMID: 22487100 PMCID: PMC3399956 DOI: 10.1111/j.1747-0285.2012.01392.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 03/07/2012] [Accepted: 04/01/2012] [Indexed: 02/03/2023]
Abstract
During the past century, several epidemics of human African trypanosomiasis, a deadly disease caused by the protist Trypanosoma brucei, have afflicted sub-Saharan Africa. Over 10 000 new victims are reported each year, with hundreds of thousands more at risk. As current drug treatments are either highly toxic or ineffective, novel trypanocides are urgently needed. The T. brucei galactose synthesis pathway is one potential therapeutic target. Although galactose is essential for T. brucei survival, the parasite lacks the transporters required to intake galactose from the environment. UDP-galactose 4'-epimerase (TbGalE) is responsible for the epimerization of UDP-glucose to UDP-galactose and is therefore of great interest to medicinal chemists. Using molecular dynamics simulations, we investigate the atomistic motions of TbGalE in both the apo and holo states. The sampled conformations and protein dynamics depend not only on the presence of a UDP-sugar ligand, but also on the chirality of the UDP-sugar C4 atom. This dependence provides important insights into TbGalE function and may help guide future computer-aided drug discovery efforts targeting this protein.
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Affiliation(s)
- Aaron J Friedman
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093-0365, USA.
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27
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Liu Y, Bentler K, Coffee B, Chhay JS, Sarafoglou K, Fridovich-Keil JL. A Case Study of Monozygotic Twins Apparently Homozygous for a Novel Variant of UDP-Galactose 4'-epimerase (GALE) : A Complex Case of Variant GALE. JIMD Rep 2012; 7:89-98. [PMID: 23430501 DOI: 10.1007/8904_2012_153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/09/2012] [Accepted: 05/11/2012] [Indexed: 01/07/2023] Open
Abstract
Epimerase deficiency galactosemia is an autosomal recessive disorder that results from partial impairment of UDP-galactose 4'-epimerase (GALE), the third enzyme in the Leloir pathway of galactose metabolism. Clinical severity of epimerase deficiency ranges from potentially lethal to apparently benign, likely reflecting the extent of GALE enzyme impairment, among other factors. We report here a case study of monozygotic twins identified by newborn screening with elevated total galactose and normal galactose-1P uridylyltransferase (GALT). Follow-up testing revealed partial impairment of GALE in hemolysates but near-normal activity in lymphoblasts; molecular testing identified a missense substitution, R220W, apparently in the homozygous state. The twins were treated with dietary galactose restriction for the first 18 months of life. During this time, independent testing revealed concurrent diagnoses of Williams Syndrome in both twins, and cytomegalovirus (CMV) infection in one. Expression studies of R220W-hGALE in a null-background strain of Saccharomyces cerevisiae demonstrated a very limited impairment of V (max) for UDP-galactose (UDP-Gal) and K (m) for UDP-N-acetylgalactosamine (UDP-GalNAc), but a galactose challenge in vivo failed to uncover any evidence of impaired Leloir function. Similarly, both twins demonstrated normal hemolysate galactose-1-phosphate (Gal-1P) levels following normalization of their diets at 18 months of age. While these studies cannot rule out a negative consequence from some cryptic GALE impairment in a specific tissue or developmental stage, they suggest that the substitution, R220W, is mild to neutral, so that any GALE impairment in these twins is likely to be peripheral and therefore unlikely to be the cause of the negative outcomes observed.
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Affiliation(s)
- Ying Liu
- Department of Human Genetics, Emory University, School of Medicine, Room 325.2 Whitehead Building, 615 Michael Street, Atlanta, GA, 30322, USA
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28
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McCorvie TJ, Liu Y, Frazer A, Gleason TJ, Fridovich-Keil JL, Timson DJ. Altered cofactor binding affects stability and activity of human UDP-galactose 4'-epimerase: implications for type III galactosemia. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1516-26. [PMID: 22613355 DOI: 10.1016/j.bbadis.2012.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 02/04/2023]
Abstract
Deficiency of UDP-galactose 4'-epimerase is implicated in type III galactosemia. Two variants, p.K161N-hGALE and p.D175N-hGALE, have been previously found in combination with other alleles in patients with a mild form of the disease. Both variants were studied in vivo and in vitro and showed different levels of impairment. p.K161N-hGALE was severely impaired with substantially reduced enzymatic activity, increased thermal stability, reduced cofactor binding and no ability to rescue the galactose-sensitivity of gal10-null yeast. Interestingly p.K161N-hGALE showed less impairment of activity with UDP-N-acetylgalactosamine in comparison to UDP-galactose. Differential scanning fluorimetry revealed that p.K161N-hGALE was more stable than the wild-type protein and only changed stability in the presence of UDP-N-acetylglucosamine and NAD(+). p.D175N-hGALE essentially rescued the galactose-sensitivity of gal10-null yeast, was less stable than the wild-type protein but showed increased stability in the presence of substrates and cofactor. We postulate that p.K161N-hGALE causes its effects by abolishing an important interaction between the protein and the cofactor, whereas p.D175N-hGALE is predicted to remove a stabilizing salt bridge between the ends of two α-helices that contain residues that interact with NAD(+). These results suggest that the cofactor binding is dynamic and that its loss results in significant structural changes that may be important in disease causation.
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Affiliation(s)
- Thomas J McCorvie
- School of Biological Sciences, Queen's University, Belfast, BT9 7BL, UK
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29
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Chung SK, Ryu SI, Lee SB. Characterization of UDP-glucose 4-epimerase from Pyrococcus horikoshii: regeneration of UDP to produce UDP-galactose using two-enzyme system with trehalose. BIORESOURCE TECHNOLOGY 2012; 110:423-429. [PMID: 22342090 DOI: 10.1016/j.biortech.2012.01.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/10/2012] [Accepted: 01/10/2012] [Indexed: 05/31/2023]
Abstract
A gene encoding a putative UDP-glucose 4-epimerase (pGALE) in Pyrococcus horikoshii was cloned and expressed in Escherichia coli. The purified enzyme could reversibly catalyze both the synthesis of UDP-Gal and UDP-Glc but preferred the binding of UDP-Gal by approximately 10-fold. The optimum pH and temperature were 6.5 and 65°C. The enzyme acted effectively without the addition of nicotinamide adenine dinucleotide (NAD(+)), possibly due to the presence of tightly bound NAD(+). In particular, pGALE could be coupled with trehalose synthase (TreT) from P. horikoshii to regenerate UDP-Gal from UDP. The possible byproduct of glycosyltransferase, UDP, was capable of being converted to UDP-Glc with trehalose by TreT, and UDP-Glc was simultaneously converted to UDP-Gal by pGALE. Conclusively, the results suggest that pGALE and TreT with trehalose is an effective one-pot two-enzyme system for the regeneration of UDP-Gal, a high-cost substrate of galactosyltransferase, to complete a sugar nucleotide cycle.
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Affiliation(s)
- Seung-Kyung Chung
- Department of Food and Nutrition, Brain Korea 21 Project, Yonsei University, Seoul 120-749, Republic of Korea
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30
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McCorvie TJ, Wasilenko J, Liu Y, Fridovich-Keil JL, Timson DJ. In vivo and in vitro function of human UDP-galactose 4'-epimerase variants. Biochimie 2011; 93:1747-54. [PMID: 21703329 PMCID: PMC3168732 DOI: 10.1016/j.biochi.2011.06.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 06/09/2011] [Indexed: 12/03/2022]
Abstract
Type III galactosemia results from reduced activity of the enzyme UDP-galactose 4'-epimerase. Five disease-associated alleles (G90E, V94M, D103G, N34S and L183P) and three artificial alleles (Y105C, N268D, and M284K) were tested for their ability to alleviate galactose-induced growth arrest in a Saccharomyces cerevisiae strain which lacks endogenous UDP-galactose 4'-epimerase. For all of these alleles, except M284K, the ability to alleviate galactose sensitivity was correlated with the UDP-galactose 4'-epimerase activity detected in cell extracts. The M284K allele, however, was able to substantially alleviate galactose sensitivity, but demonstrated near-zero activity in cell extracts. Recombinant expression of the corresponding protein in Escherichia coli resulted in a protein with reduced enzymatic activity and reduced stability towards denaturants in vitro. This lack of stability may result from the introduction of an unpaired positive charge into a bundle of three α-helices near the surface of the protein. The disparities between the in vivo and in vitro data for M284K-hGALE further suggest that there are additional, stabilising factors present in the cell. Taken together, these results reinforce the need for care in the interpretation of in vitro, enzymatic diagnostic tests for type III galactosemia.
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Affiliation(s)
- Thomas J. McCorvie
- School of Biological Sciences, Queen’s University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Jamie Wasilenko
- Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia, USA
| | - Ying Liu
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - David J. Timson
- School of Biological Sciences, Queen’s University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
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31
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Agnew A, Timson D. Mechanistic studies on human N-acetylgalactosamine kinase. J Enzyme Inhib Med Chem 2010; 25:370-6. [PMID: 19874134 DOI: 10.3109/14756360903179492] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
N-Acetylgalactosamine kinase (GALK2) is a small molecule kinase from the GHMP family which phosphorylates N-acetylgalactosamine at the expense of ATP. Recombinant GALK2 expressed in, and purified from, Escherichia coli was shown to be active with the following kinetic parameters: Michaelis constant for ATP, 14 +/- 3 microM; Michaelis constant for N-acetylgalactosamine, 40 +/- 14 microM; and turnover number, 1.0 +/- 0.1 s(-1). The combination of substrate inhibition by N-acetylgalactosamine and alpha-methylgalactopyranoside acting as an uncompetitive inhibitor with respect to ATP suggested that the enzyme has an ordered ternary complex mechanism in which ATP is the first substrate to bind. The effects of pH on the kinetic parameters provided evidence for ionizable residues playing a role in substrate binding and catalysis. These results are discussed in the context of the mechanisms of the GHMP kinases.
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Affiliation(s)
- Andrew Agnew
- Queen's University Belfast, Belfast, United Kingdom
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32
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Abstract
Galactosemia is caused by inherited deficiencies in one of three enzymes involved in the metabolism of galactose: galactose-1-phosphate uridyltransferase (GALT), galactokinase (GALK), and uridine diphosphate galactose-4-epimerase (GALE). The rarest and most poorly understood form of galactosemia is due to epimerase deficiency. We are reporting such a rarest form of galactosemia presenting with progressively increasing cholestatic jaundice and failure to thrive at one month of age. After confirmation of decreased epimerase level in RBC hemolysate, the patient was put on galactose restricted diet and vitamins supplementation, which reversed the clinical signs as well as altered liver function. Patient is on regular follow-up and now at 15 months of age he has no marked developmental delay.
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33
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Bang YL, Nguyen TTT, Trinh TTB, Kim YJ, Song J, Song YH. Functional analysis of mutations in UDP-galactose-4-epimerase (GALE) associated with galactosemia in Korean patients using mammalian GALE-null cells. FEBS J 2009; 276:1952-61. [DOI: 10.1111/j.1742-4658.2009.06922.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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34
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Pathmanathan S, Elliott SF, McSwiggen S, Greer B, Harriott P, Irvine GB, Timson DJ. IQ motif selectivity in human IQGAP1: binding of myosin essential light chain and S100B. Mol Cell Biochem 2008; 318:43-51. [PMID: 18587628 DOI: 10.1007/s11010-008-9855-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/13/2008] [Indexed: 02/06/2023]
Abstract
IQGAPs are cytoskeletal scaffolding proteins which link signalling pathways to the reorganisation of actin and microtubules. Human IQGAP1 has four IQ motifs each of which binds to calmodulin. The same region has been implicated in binding to two calmodulin-like proteins, the myosin essential light chain Mlc1sa and the calcium and zinc ion binding protein S100B. Using synthetic peptides corresponding to the four IQ motifs of human IQGAP1, we showed by native gel electrophoresis that only the first IQ motif interacts with Mlc1sa. This IQ motif, and also the fourth, interacts with the budding yeast myosin essential light chain Mlc1p. The first and second IQ motifs interact with S100B in the presence of calcium ions. This clearly establishes that S100B can interact with its targets through IQ motifs in addition to interacting via previously reported sequences. These results are discussed in terms of the function of IQGAP1 and IQ motif recognition.
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Affiliation(s)
- Sevvel Pathmanathan
- Medical Biology Centre, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
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35
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Chhay JS, Vargas CA, McCorvie TJ, Fridovich-Keil JL, Timson DJ. Analysis of UDP-galactose 4'-epimerase mutations associated with the intermediate form of type III galactosaemia. J Inherit Metab Dis 2008; 31:108-16. [PMID: 18188677 DOI: 10.1007/s10545-007-0790-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 11/20/2007] [Accepted: 12/04/2007] [Indexed: 11/29/2022]
Abstract
Type III galactosaemia is a hereditary disease caused by reduced activity in the Leloir pathway enzyme, UDP-galactose 4'-epimerase (GALE). Traditionally, the condition has been divided into two forms-a mild, or peripheral, form and a severe, or generalized, form. Recently it has become apparent that there are disease states which are intermediate between these two extremes. Three mutations associated with this intermediate form (S81R, T150M and P293L) were analysed for their kinetic and structural properties in vitro and their effects on galactose-sensitivity of Saccharomyces cerevisiae cells that were deleted for the yeast GALE homologue Gal10p. All three mutations result in impairment of the kinetic parameters (principally the turnover number, k (cat)) compared with the wild-type enzyme. However, the degree of impairment was mild compared with that seen with the mutation (V94M) associated with the generalized form of epimerase deficiency galactosaemia. None of the three mutations tested affected the ability of the protein to dimerize in solution or its susceptibility to limited proteolysis in vitro. Finally, in the yeast model, each of the mutated patient alleles was able to complement the galactose-sensitivity of gal10Delta cells as fully as was the wild-type human allele. Furthermore, there was no difference from control in metabolite profile following galactose exposure for any of these strains. Thus we conclude that the subtle biochemical and metabolic abnormalities detected in patients expressing these GALE alleles likely reflect, at least in part, the reduced enzymatic activity of the encoded GALE proteins.
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Affiliation(s)
- J S Chhay
- Department of Human Genetics, Emory University School of Medicine, Emory University, Atlanta, Georgia, USA
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36
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Sellick CA, Campbell RN, Reece RJ. Galactose metabolism in yeast-structure and regulation of the leloir pathway enzymes and the genes encoding them. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 269:111-50. [PMID: 18779058 DOI: 10.1016/s1937-6448(08)01003-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The enzymes of the Leloir pathway catalyze the conversion of galactose to a more metabolically useful version, glucose-6-phosphate. This pathway is required as galactose itself cannot be used for glycolysis directly. In most organisms, including the yeast Saccharomyces cerevisiae, five enzymes are required to catalyze this conversion: a galactose mutarotase, a galactokinase, a galactose-1-phosphate uridyltransferase, a UDP-galactose-4-epimerase, and a phosphoglucomutase. In yeast, the genes encoding these enzymes are tightly controlled at the level of transcription and are only transcribed under specific sets of conditions. In the presence of glucose, the genes encoding the Leloir pathway enzymes (often called the GAL genes) are repressed through the action of a transcriptional repressor Mig1p. In the presence of galactose, but in the absence of glucose, the concerted actions of three other proteins Gal4p, Gal80p, and Gal3p, and two small molecules (galactose and ATP) enable the rapid and high-level activation of the GAL genes. The precise molecular mechanism of the GAL genetic switch is controversial. Recent work on solving the three-dimensional structures of the various GAL enzymes proteins and the GAL transcriptional switch proteins affords a unique opportunity to delve into the precise, and potentially unambiguous, molecular mechanism of a highly exploited transcriptional circuit. Understanding the details of the transcriptional and metabolic events that occur in this pathway can be used as a paradigm for understanding the integration of metabolism and transcriptional control more generally, and will assist our understanding of fundamental biochemical processes and how these might be exploited.
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37
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Scott A, Timson DJ. Characterization of theSaccharomyces cerevisiaegalactose mutarotase/UDP-galactose 4-epimerase protein, Gal10p. FEMS Yeast Res 2007; 7:366-71. [PMID: 17253981 DOI: 10.1111/j.1567-1364.2006.00204.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Saccharomyces cerevisiae and some related yeasts are unusual in that two of the enzyme activities (galactose mutarotase and UDP-galactose 4-epimerase) required for the Leloir pathway of d-galactose catabolism are contained within a single protein-Gal10p. The recently solved structure of the protein shows that the two domains are separate and have similar folds to the separate enzymes from other species. The biochemical properties of Gal10p have been investigated using recombinant protein expressed in, and purified from, Escherichia coli. Protein-protein crosslinking confirmed that Gal10p is a dimer in solution and this state is unaffected by the presence of substrates. The steady-state kinetic parameters of the epimerase reaction are similar to those of the human enzyme, and are not affected by simultaneous activity at the mutarotase active site. The mutarotase active site has a strong preference for galactose over glucose, and is not affected by simultaneous epimerase activity. This absence of reciprocal kinetic effects between the active sites suggests that they act independently and do not influence or regulate each other.
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Affiliation(s)
- Aaron Scott
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, Belfast, UK
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