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Chen Y, Li Y, Gao J, Yu Q, Zhang Y, Zhang J. Perspectives and challenges in developing small molecules targeting purine nucleoside phosphorylase. Eur J Med Chem 2024; 271:116437. [PMID: 38701712 DOI: 10.1016/j.ejmech.2024.116437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 05/05/2024]
Abstract
As a cytosolic enzyme involved in the purine salvage pathway metabolism, purine nucleoside phosphorylase (PNP) plays an important role in a variety of cellular functions but also in immune system, including cell growth, apoptosis and cancer development and progression. Based on its T-cell targeting profile, PNP is a potential target for the treatment of some malignant T-cell proliferative cancers including lymphoma and leukemia, and some specific immunological diseases. Numerous small-molecule PNP inhibitors have been developed so far. However, only Peldesine, Forodesine and Ulodesine have entered clinical trials and exhibited some potential for the treatment of T-cell leukemia and gout. The most recent direction in PNP inhibitor development has been focused on PNP small-molecule inhibitors with better potency, selectivity, and pharmacokinetic property. In this perspective, considering the structure, biological functions, and disease relevance of PNP, we highlight the recent research progress in PNP small-molecule inhibitor development and discuss prospective strategies for designing additional PNP therapeutic agents.
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Affiliation(s)
- Yangyang Chen
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Yang Li
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Jing Gao
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Quanwei Yu
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China; Department of Respiratory and Critical Care Medicine, Targeted Tracer Research and Development Laboratory, Institute of Respiratory Health, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
| | - Yiwen Zhang
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
| | - Jifa Zhang
- Department of Neurology, Laboratory of Neuro-system and Multimorbidity and State Key Laboratory of Biotherapy and Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
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Timofeev VI, Fateev IV, Kostromina MA, Abramchik YA, Konstantinova ID, Volkov VV, Lykoshin DD, Mikheeva OO, Muravieva TI, Esipov RS, Kuranova IP. The comparative analysis of the properties and structures of purine nucleoside phosphorylases from thermophilic bacterium Thermus thermophilus HB27. J Biomol Struct Dyn 2020; 40:3626-3641. [PMID: 33225840 DOI: 10.1080/07391102.2020.1848628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Two recombinant purine nucleoside phosphorylases from thermophilic bacterium Thermus thermophilus HB27 encoded by genes TT_C1070 (TthPNPI) and TT_C0194 (TthPNPII) were purified and characterized. The comparative analysis of their sequences, molecular weight, enzymes specificity and kinetics of the catalyzed reaction were realized. As a result, it was determined that the TthPNPI is specific to guanosine while the TthPNPII to adenosine. According to the results of the size exclusion chromatography and SAXS study both enzymes are hexameric molecules. Based on the sequence alignment with homologous purine nucleoside phosphorylases (PNPs), Asn was identified as a purine base recognizing residue in the active site of TthPNPI and Asp in TthPNPII. The three-dimensional structure of TthPNPII was solved at 2.5 Å resolution by molecular replacement method using crystals grown in microgravity. Position of phosphate in the active site cavity is located. The possible arrangement of adenosine and guanosine in TthPNPII active site cavity is considered using superposition with the structures of homologous trimeric and hexameric PNPs complexed with corresponding substrates. The peculiarities of oligomeric structure of TthPNPII in comparison with homologous PNPs are described. It is shown that two trimeric molecules of TthPNPII in the asymmetric part of the unit cell are connected by three two-fold axis into a hexamer with 32-point symmetry. This type of hexameric structure of PNP is found for the first time. The interface area between the subunits in trimeric molecule and between the trimers in TthPNPII hexamer is described.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Vladimir I Timofeev
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Moscow, Russian Federation
| | - Ilya V Fateev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Maria A Kostromina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Yuliya A Abramchik
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Irina D Konstantinova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir V Volkov
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Moscow, Russian Federation
| | - Dmitry D Lykoshin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Olga O Mikheeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Tatiana I Muravieva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Roman S Esipov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Inna P Kuranova
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Moscow, Russian Federation
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3
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Cader MZ, de Almeida Rodrigues RP, West JA, Sewell GW, Md-Ibrahim MN, Reikine S, Sirago G, Unger LW, Iglesias-Romero AB, Ramshorn K, Haag LM, Saveljeva S, Ebel JF, Rosenstiel P, Kaneider NC, Lee JC, Lawley TD, Bradley A, Dougan G, Modis Y, Griffin JL, Kaser A. FAMIN Is a Multifunctional Purine Enzyme Enabling the Purine Nucleotide Cycle. Cell 2020; 180:278-295.e23. [PMID: 31978345 PMCID: PMC6978800 DOI: 10.1016/j.cell.2019.12.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 11/18/2019] [Accepted: 12/12/2019] [Indexed: 12/11/2022]
Abstract
Mutations in FAMIN cause arthritis and inflammatory bowel disease in early childhood, and a common genetic variant increases the risk for Crohn's disease and leprosy. We developed an unbiased liquid chromatography-mass spectrometry screen for enzymatic activity of this orphan protein. We report that FAMIN phosphorolytically cleaves adenosine into adenine and ribose-1-phosphate. Such activity was considered absent from eukaryotic metabolism. FAMIN and its prokaryotic orthologs additionally have adenosine deaminase, purine nucleoside phosphorylase, and S-methyl-5′-thioadenosine phosphorylase activity, hence, combine activities of the namesake enzymes of central purine metabolism. FAMIN enables in macrophages a purine nucleotide cycle (PNC) between adenosine and inosine monophosphate and adenylosuccinate, which consumes aspartate and releases fumarate in a manner involving fatty acid oxidation and ATP-citrate lyase activity. This macrophage PNC synchronizes mitochondrial activity with glycolysis by balancing electron transfer to mitochondria, thereby supporting glycolytic activity and promoting oxidative phosphorylation and mitochondrial H+ and phosphate recycling. An unbiased LC-MS screen reveals FAMIN as a purine nucleoside enzyme FAMIN combines adenosine phosphorylase with ADA-, PNP-, and MTAP-like activities FAMIN enables a purine nucleotide cycle (PNC) preventing cytoplasmic acidification The FAMIN-dependent PNC balances the glycolysis-mitochondrial redox interface
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Affiliation(s)
- M Zaeem Cader
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Rodrigo Pereira de Almeida Rodrigues
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - James A West
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK; Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK
| | - Gavin W Sewell
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Muhammad N Md-Ibrahim
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Stephanie Reikine
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Giuseppe Sirago
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Lukas W Unger
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Ana Belén Iglesias-Romero
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Katharina Ramshorn
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Lea-Maxie Haag
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Svetlana Saveljeva
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Jana-Fabienne Ebel
- Institute of Clinical Molecular Biology, Christian Albrechts University, Campus Kiel, 24105 Kiel, Germany
| | - Philip Rosenstiel
- Institute of Clinical Molecular Biology, Christian Albrechts University, Campus Kiel, 24105 Kiel, Germany
| | - Nicole C Kaneider
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - James C Lee
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Allan Bradley
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | - Gordon Dougan
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Infectious Diseases, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Yorgo Modis
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Julian L Griffin
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge CB2 1GA, UK
| | - Arthur Kaser
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK; Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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Il’icheva IA, Polyakov KM, Mikhailov SN. Strained Conformations of Nucleosides in Active Sites of Nucleoside Phosphorylases. Biomolecules 2020; 10:E552. [PMID: 32260512 PMCID: PMC7226091 DOI: 10.3390/biom10040552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/26/2020] [Accepted: 04/01/2020] [Indexed: 11/28/2022] Open
Abstract
Nucleoside phosphorylases catalyze the reversible phosphorolysis of nucleosides to heterocyclic bases, giving α-d-ribose-1-phosphate or α-d-2-deoxyribose-1-phosphate. These enzymes are involved in salvage pathways of nucleoside biosynthesis. The level of these enzymes is often elevated in tumors, which can be used as a marker for cancer diagnosis. This review presents the analysis of conformations of nucleosides and their analogues in complexes with nucleoside phosphorylases of the first (NP-1) family, which includes hexameric and trimeric purine nucleoside phosphorylases (EC 2.4.2.1), hexameric and trimeric 5'-deoxy-5'-methylthioadenosine phosphorylases (EC 2.4.2.28), and uridine phosphorylases (EC 2.4.2.3). Nucleosides adopt similar conformations in complexes, with these conformations being significantly different from those of free nucleosides. In complexes, pentofuranose rings of all nucleosides are at the W region of the pseudorotation cycle that corresponds to the energy barrier to the N↔S interconversion. In most of the complexes, the orientation of the bases with respect to the ribose is in the high-syn region in the immediate vicinity of the barrier to syn ↔ anti transitions. Such conformations of nucleosides in complexes are unfavorable when compared to free nucleosides and they are stabilized by interactions with the enzyme. The sulfate (or phosphate) ion in the active site of the complexes influences the conformation of the furanose ring. The binding of nucleosides in strained conformations is a characteristic feature of the enzyme-substrate complex formation for this enzyme group.
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Affiliation(s)
| | | | - Sergey N. Mikhailov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Str. 32, 119991 Moscow, Russia; (I.A.I.); (K.M.P.)
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Sinitsyna EV, Timofeev VI, Zhukhlistova NE, Muravieva TI, Kostromina MA, Esipov RS, Kuranova IP. Crystallization and Preliminary X-ray Diffraction Study of Purine Nucleoside Phosphorylase from the Thermophilic Bacterium Thermus thermophilus Strain HB27. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s1063774518050279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Timofeev VI, Zhukhlistova NE, Abramchik YA, Muravieva TI, Esipov RS, Kuranova IP. Crystal structure of Escherichia coli purine nucleoside phosphorylase complexed with acyclovir. Acta Crystallogr F Struct Biol Commun 2018; 74:402-409. [PMID: 29969103 PMCID: PMC6038453 DOI: 10.1107/s2053230x18008087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/31/2018] [Indexed: 11/10/2022] Open
Abstract
Escherichia coli purine nucleoside phosphorylase (PNP), which catalyzes the reversible phosphorolysis of purine ribonucleosides, belongs to the family I hexameric PNPs. Owing to their key role in the purine salvage pathway, PNPs are attractive targets for drug design against some pathogens. Acyclovir (ACV) is an acyclic derivative of the PNP substrate guanosine and is used as an antiviral drug for the treatment of some human viral infections. The crystalline complex of E. coli PNP with acyclovir was prepared by co-crystallization in microgravity using counter-diffusion through a gel layer in a capillary. The structure of the E. coli PNP-ACV complex was solved at 2.32 Å resolution using the molecular-replacement method. The ACV molecule is observed in two conformations and sulfate ions were located in both the nucleoside-binding and phosphate-binding pockets of the enzyme. A comparison with the complexes of other hexameric and trimeric PNPs with ACV shows the similarity in acyclovir binding by these enzymes.
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Affiliation(s)
- Vladimir I. Timofeev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Nadezhda E. Zhukhlistova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
| | - Yuliya A. Abramchik
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Tatiana I. Muravieva
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Roman S. Esipov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Inna P. Kuranova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
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Timofeev VI, Zhukhlistova NE, Abramchik YA, Fateev II, Kostromina MA, Muravieva TI, Esipov RS, Kuranova IP. Crystal structure of Escherichia coli purine nucleoside phosphorylase in complex with 7-deazahypoxanthine. Acta Crystallogr F Struct Biol Commun 2018; 74:355-362. [PMID: 29870020 PMCID: PMC5987744 DOI: 10.1107/s2053230x18006337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/25/2018] [Indexed: 11/10/2022] Open
Abstract
Purine nucleoside phosphorylases (EC 2.4.2.1; PNPs) reversibly catalyze the phosphorolytic cleavage of glycosidic bonds in purine nucleosides to generate ribose 1-phosphate and a free purine base, and are key enzymes in the salvage pathway of purine biosynthesis. They also catalyze the transfer of pentosyl groups between purine bases (the transglycosylation reaction) and are widely used for the synthesis of biologically important analogues of natural nucleosides, including a number of anticancer and antiviral drugs. Potent inhibitors of PNPs are used in chemotherapeutic applications. The detailed study of the binding of purine bases and their derivatives in the active site of PNPs is of particular interest in order to understand the mechanism of enzyme action and for the development of new enzyme inhibitors. Here, it is shown that 7-deazahypoxanthine (7DHX) is a noncompetitive inhibitor of the phosphorolysis of inosine by recombinant Escherichia coli PNP (EcPNP) with an inhibition constant Ki of 0.13 mM. A crystal of EcPNP in complex with 7DHX was obtained in microgravity by the counter-diffusion technique and the three-dimensional structure of the EcPNP-7DHX complex was solved by molecular replacement at 2.51 Å resolution using an X-ray data set collected at the SPring-8 synchrotron-radiation facility, Japan. The crystals belonged to space group P6122, with unit-cell parameters a = b = 120.370, c = 238.971 Å, and contained three subunits of the hexameric enzyme molecule in the asymmetric unit. The 7DHX molecule was located with full occupancy in the active site of each of the three crystallographically independent enzyme subunits. The position of 7DHX overlapped with the positions occupied by purine bases in similar PNP complexes. However, the orientation of the 7DHX molecule differs from those of other bases: it is rotated by ∼180° relative to other bases. The peculiarities of the arrangement of 7DHX in the EcPNP active site are discussed.
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Affiliation(s)
- Vladimir I. Timofeev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Nadezhda E. Zhukhlistova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
| | - Yuliya A. Abramchik
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Ilya I. Fateev
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Maria A. Kostromina
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Tatiana I. Muravieva
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Roman S. Esipov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Inna P. Kuranova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
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9
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La Sala G, Decherchi S, De Vivo M, Rocchia W. Allosteric Communication Networks in Proteins Revealed through Pocket Crosstalk Analysis. ACS CENTRAL SCIENCE 2017; 3:949-960. [PMID: 28979936 PMCID: PMC5620967 DOI: 10.1021/acscentsci.7b00211] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 05/17/2023]
Abstract
The detection and characterization of binding pockets and allosteric communication in proteins is crucial for studying biological regulation and performing drug design. Nowadays, ever-longer molecular dynamics (MD) simulations are routinely used to investigate the spatiotemporal evolution of proteins. Yet, there is no computational tool that can automatically detect all the pockets and potential allosteric communication networks along these extended MD simulations. Here, we use a novel and fully automated algorithm that examines pocket formation, dynamics, and allosteric communication embedded in microsecond-long MD simulations of three pharmaceutically relevant proteins, namely, PNP, A2A, and Abl kinase. This dynamic analysis uses pocket crosstalk, defined as the temporal exchange of atoms between adjacent pockets, along the MD trajectories as a fingerprint of hidden allosteric communication networks. Importantly, this study indicates that dynamic pocket crosstalk analysis provides new mechanistic understandings on allosteric communication networks, enriching the available experimental data. Thus, our results suggest the prospective use of this unprecedented dynamic analysis to characterize transient binding pockets for structure-based drug design.
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Affiliation(s)
- Giuseppina La Sala
- Laboratory
of Molecular Modeling and Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Sergio Decherchi
- CONCEPT
Lab, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- BiKi
Technologies s.r.l., via XX Settembre 33, 16121 Genova, Italy
| | - Marco De Vivo
- Laboratory
of Molecular Modeling and Drug Discovery, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- IAS-S/INM-9
Computational Biomedicine Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
- Phone: +39 01071781577. E-mail:
| | - Walter Rocchia
- CONCEPT
Lab, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Phone: +39 01071781552. E-mail:
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Verma P, Patel GK, Kar B, Sharma AK. A case of neofunctionalization of a Putranjiva roxburghii PNP protein to trypsin inhibitor by disruption of PNP-UDP domain through an insert containing inhibitory site. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 260:19-30. [PMID: 28554472 DOI: 10.1016/j.plantsci.2017.03.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/11/2017] [Accepted: 03/25/2017] [Indexed: 05/24/2023]
Abstract
The attainment of new function by a protein is achieved through convergent/divergent evolution. In present work, the sequence analysis of a 34kDa protein from Putranjiva roxburghii, earlier reported as a potent trypsin inhibitor, showed resemblance to some of the wound inducible and vegetative storage proteins. A detailed sequence analysis revealed that these proteins belong to PNP-UDP family. In case of P. roxburghii protein, an approximately 46 residue insert disrupts the PNP domain. Similar disruption of PNP domain is observed in related plant proteins. The characterization of recombinant full length and truncated (without 46 residue insert) forms of P. roxburghii PNP family protein (PRpnp) unraveled that trypsin inhibitory active site is located within the insert. The truncated form containing uninterrupted PNP domain showed strong PNP enzymatic activity where it hydrolyzed the N-glycosidic bond of inosine and guanosine. The full length protein, however, showed weak PNP enzyme activity which may be due to presence of the insert. These results indicate towards the neofunctionalization of PRpnp to a potent trypsin inhibitor through an insert containing inhibitory residue to cater to the needs of plant defense. The similar wound inducible and vegetative storage proteins may have also evolved due to evolutionary needs.
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Affiliation(s)
- Preeti Verma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
| | - Girijesh K Patel
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
| | - Bibekananda Kar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
| | - Ashwani K Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247 667, India.
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11
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Catalytic-site design for inverse heavy-enzyme isotope effects in human purine nucleoside phosphorylase. Proc Natl Acad Sci U S A 2017; 114:6456-6461. [PMID: 28584087 DOI: 10.1073/pnas.1704786114] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Heavy-enzyme isotope effects (15N-, 13C-, and 2H-labeled protein) explore mass-dependent vibrational modes linked to catalysis. Transition path-sampling (TPS) calculations have predicted femtosecond dynamic coupling at the catalytic site of human purine nucleoside phosphorylase (PNP). Coupling is observed in heavy PNPs, where slowed barrier crossing caused a normal heavy-enzyme isotope effect (kchemlight/kchemheavy > 1.0). We used TPS to design mutant F159Y PNP, predicted to improve barrier crossing for heavy F159Y PNP, an attempt to generate a rare inverse heavy-enzyme isotope effect (kchemlight/kchemheavy < 1.0). Steady-state kinetic comparison of light and heavy native PNPs to light and heavy F159Y PNPs revealed similar kinetic properties. Pre-steady-state chemistry was slowed 32-fold in F159Y PNP. Pre-steady-state chemistry compared heavy and light native and F159Y PNPs and found a normal heavy-enzyme isotope effect of 1.31 for native PNP and an inverse effect of 0.75 for F159Y PNP. Increased isotopic mass in F159Y PNP causes more efficient transition state formation. Independent validation of the inverse isotope effect for heavy F159Y PNP came from commitment to catalysis experiments. Most heavy enzymes demonstrate normal heavy-enzyme isotope effects, and F159Y PNP is a rare example of an inverse effect. Crystal structures and TPS dynamics of native and F159Y PNPs explore the catalytic-site geometry associated with these catalytic changes. Experimental validation of TPS predictions for barrier crossing establishes the connection of rapid protein dynamics and vibrational coupling to enzymatic transition state passage.
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12
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Isaksen GV, Åqvist J, Brandsdal BO. Thermodynamics of the Purine Nucleoside Phosphorylase Reaction Revealed by Computer Simulations. Biochemistry 2016; 56:306-312. [DOI: 10.1021/acs.biochem.6b00967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Geir Villy Isaksen
- The
Centre for Theoretical and Computational Chemistry, Department of
Chemistry, University of Tromsø, NO-9037 Tromsø, Norway
| | - Johan Åqvist
- Department
of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124 Uppsala, Sweden
| | - Bjørn Olav Brandsdal
- The
Centre for Theoretical and Computational Chemistry, Department of
Chemistry, University of Tromsø, NO-9037 Tromsø, Norway
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13
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Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food. PLoS One 2016; 11:e0164279. [PMID: 27768715 PMCID: PMC5074518 DOI: 10.1371/journal.pone.0164279] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 09/22/2016] [Indexed: 01/19/2023] Open
Abstract
Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNPN256D and KlacPNPN256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNPN256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNPN256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNPN256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNPN256D has broad substrate specificity, a combination of engineered KlacPNP and other enzymes involved in purine degradation could effectively lower the purine content in foods and beverages.
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Boyko KM, Timofeev VI, Samygina VR, Kuranova IP, Popov VO, Koval’chuk MV. Protein crystallization under microgravity conditions. Analysis of the results of Russian experiments performed on the International Space Station in 2005−2015. CRYSTALLOGR REP+ 2016. [DOI: 10.1134/s1063774516050059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Isaksen GV, Hopmann KH, Åqvist J, Brandsdal BO. Computer Simulations Reveal Substrate Specificity of Glycosidic Bond Cleavage in Native and Mutant Human Purine Nucleoside Phosphorylase. Biochemistry 2016; 55:2153-62. [PMID: 26985580 DOI: 10.1021/acs.biochem.5b01347] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of purine ribonucleosides and 2'-deoxyribonucleosides, yielding the purine base and (2'-deoxy)ribose 1-phosphate as products. While this enzyme has been extensively studied, several questions with respect to the catalytic mechanism have remained largely unanswered. The role of the phosphate and key amino acid residues in the catalytic reaction as well as the purine ring protonation state is elucidated using density functional theory calculations and extensive empirical valence bond (EVB) simulations. Free energy surfaces for adenosine, inosine, and guanosine are fitted to ab initio data and yield quantitative agreement with experimental data when the surfaces are used to model the corresponding enzymatic reactions. The cognate substrates 6-aminopurines (inosine and guanosine) interact with PNP through extensive hydrogen bonding, but the substrate specificity is found to be a direct result of the electrostatic preorganization energy along the reaction coordinate. Asn243 has previously been identified as a key residue providing substrate specificity. Mutation of Asn243 to Asp has dramatic effects on the substrate specificity, making 6-amino- and 6-oxopurines equally good as substrates. The principal effect of this particular mutation is the change in the electrostatic preorganization energy between the native enzyme and the Asn243Asp mutant, clearly favoring adenosine over inosine and guanosine. Thus, the EVB simulations show that this particular mutation affects the electrostatic preorganization of the active site, which in turn can explain the substrate specificity.
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Affiliation(s)
- Geir Villy Isaksen
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
| | - Kathrin Helen Hopmann
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
| | - Johan Åqvist
- Department of Cell & Molecular Biology, Uppsala University , SE-75124 Uppsala, Sweden
| | - Bjørn Olav Brandsdal
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
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Timofeev VI, Abramchik YA, Zhukhlistova NE, Muravieva TI, Esipov RS, Kuranova IP. Three-dimensional structure of E. Coli purine nucleoside phosphorylase at 0.99 Å resolution. CRYSTALLOGR REP+ 2016. [DOI: 10.1134/s1063774516020292] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Abramchik YA, Timofeev VI, Zhukhlistova NE, Muravieva TI, Esipov RS, Kuranova IP. Purification, crystallization, and preliminary X-ray diffraction study of purine nucleoside phosphorylase from E. coli. CRYSTALLOGR REP+ 2015. [DOI: 10.1134/s1063774515040021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Podok P, Xu L, Xu D, Lu L. Different expression profiles of Interleukin 11 (IL-11), Intelectin (ITLN) and Purine nucleoside phosphorylase 5a (PNP 5a) in crucian carp (Carassius auratus gibelio) in response to Cyprinid herpesvirus 2 and Aeromonas hydrophila. FISH & SHELLFISH IMMUNOLOGY 2014; 38:65-73. [PMID: 24636855 DOI: 10.1016/j.fsi.2014.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/25/2014] [Accepted: 03/05/2014] [Indexed: 06/03/2023]
Abstract
Interleukin 11 (IL-11), Intelectin (ITLN) and Purine nucleoside phosphorylase 5a (PNP5a) play important roles in innate immunity. In a previous study to identify differentially expressed immune-related genes, suppression subtractive hybridization (SSH) assay was used to characterize differentially expressed genes in crucian carp (Carassius auratus gibelio) infected with Cyprinid herpesvirus 2 (CyHV-2) in which IL-11, ITLN and PNP5a were identified to be the three most significantly up-regulated genes (Xu et al., Archives of Virology, 2014, http://dx.doi.org/10.1007/s00705-014-2011-9). In this study, the complete open reading frames (ORF) of IL-11, ITLN and PNP5a genes were cloned and sequenced. The full-length cDNAs of the three genes contained an ORF of 597, 945 and 882 bp, encoding a polypeptide of 198, 314 and 293 amino acids, respectively. Phylogenetic analysis indicated that the three genes shared high homology to other bony fish species including Zebrafish. Interestingly, the ITLN gene of crucian carp lacked a 10 aa peptide that was found in the C-terminal of other fish species. A real-time RT-PCR assay was developed to quantitatively examine their tissue distribution. We found that IL-11, ITLN and PNP5a were expressed at low levels in all of the tissues examined. To monitor the response of these genes to CyHV- 2 or Aeromonas hydrophila (A. hydrophila) infection, we determined the expression level of IL-11, ITLN and PNP5a at different time points after infection in kidney. Significant up-regulation of IL-11, ITLN and PNP5a was only observed 72 h post-CyHV-2 injection (P < 0.01), whereas significant up-regulation was observed as early as 6 h after infection with A. hydrophila (P < 0.01). Our results demonstrated that host innate immune response to CyHV-2, at least in which IL-11, ITLN and PNP5a were involved, was slow in comparison to that induced by A. hydrophila. It suggested that CyHV-2 might suppress host innate response during early infection. The lack of a C-terminal peptide of crucian carp ITLN gene implied a possible functional difference of this gene during evolution, which merit further investigation.
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Affiliation(s)
- Patarida Podok
- Key Laboratory of Aquatic Genetic Resources of the Ministry of Agriculture, Shanghai Ocean University, 201306, PR China
| | - Lijuan Xu
- Key Laboratory of Aquatic Genetic Resources of the Ministry of Agriculture, Shanghai Ocean University, 201306, PR China
| | - Dan Xu
- Key Laboratory of Aquatic Genetic Resources of the Ministry of Agriculture, Shanghai Ocean University, 201306, PR China
| | - Liqun Lu
- Key Laboratory of Aquatic Genetic Resources of the Ministry of Agriculture, Shanghai Ocean University, 201306, PR China.
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19
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A purine nucleoside phosphorylase in Solanum tuberosum L. (potato) with specificity for cytokinins contributes to the duration of tuber endodormancy. Biochem J 2014; 458:225-37. [PMID: 24325449 DOI: 10.1042/bj20130792] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
StCKP1 (Solanum tuberosum cytokinin riboside phosphorylase) catalyses the interconversion of the N9-riboside form of the plant hormone CK (cytokinin), a subset of purines, with its most active free base form. StCKP1 prefers CK to unsubstituted aminopurines. The protein was discovered as a CK-binding activity in extracts of tuberizing potato stolon tips, from which it was isolated by affinity chromatography. The N-terminal amino acid sequence matched the translation product of a set of ESTs, enabling a complete mRNA sequence to be obtained by RACE-PCR. The predicted polypeptide includes a cleavable signal peptide and motifs for purine nucleoside phosphorylase activity. The expressed protein was assayed for purine nucleoside phosphorylase activity against CKs and adenine/adenosine. Isopentenyladenine, trans-zeatin, dihydrozeatin and adenine were converted into ribosides in the presence of ribose 1-phosphate. In the opposite direction, isopentenyladenosine, trans-zeatin riboside, dihydrozeatin riboside and adenosine were converted into their free bases in the presence of Pi. StCKP1 had no detectable ribohydrolase activity. Evidence is presented that StCKP1 is active in tubers as a negative regulator of CKs, prolonging endodormancy by a chill-reversible mechanism.
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20
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Inhibition and structure of Toxoplasma gondii purine nucleoside phosphorylase. EUKARYOTIC CELL 2014; 13:572-9. [PMID: 24585883 DOI: 10.1128/ec.00308-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The intracellular pathogen Toxoplasma gondii is a purine auxotroph that relies on purine salvage for proliferation. We have optimized T. gondii purine nucleoside phosphorylase (TgPNP) stability and crystallized TgPNP with phosphate and immucillin-H, a transition-state analogue that has high affinity for the enzyme. Immucillin-H bound to TgPNP with a dissociation constant of 370 pM, the highest affinity of 11 immucillins selected to probe the catalytic site. The specificity for transition-state analogues indicated an early dissociative transition state for TgPNP. Compared to Plasmodium falciparum PNP, large substituents surrounding the 5'-hydroxyl group of inhibitors demonstrate reduced capacity for TgPNP inhibition. Catalytic discrimination against large 5' groups is consistent with the inability of TgPNP to catalyze the phosphorolysis of 5'-methylthioinosine to hypoxanthine. In contrast to mammalian PNP, the 2'-hydroxyl group is crucial for inhibitor binding in the catalytic site of TgPNP. This first crystal structure of TgPNP describes the basis for discrimination against 5'-methylthioinosine and similarly 5'-hydroxy-substituted immucillins; structural differences reflect the unique adaptations of purine salvage pathways of Apicomplexa.
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21
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Chern JW, Lin GS, Chen CS. Nucleosides 4: Synthesis of 2′,3′-Didehydro-2′,3′-dideoxydoridosine and 2′,3′-Dideoxydoridosine as Potential Antihypertensive Agents. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.199200060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Baszczyňski O, Janeba Z. Medicinal Chemistry of Fluorinated Cyclic and Acyclic Nucleoside Phosphonates. Med Res Rev 2013; 33:1304-44. [DOI: 10.1002/med.21296] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ondřej Baszczyňski
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i. Flemingovo nám. 2 16610 Prague 6 Czech Republic
| | - Zlatko Janeba
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i. Flemingovo nám. 2 16610 Prague 6 Czech Republic
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23
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Pallotta V, D’Alessandro A, Rinalducci S, Zolla L. Native Protein Complexes in the Cytoplasm of Red Blood Cells. J Proteome Res 2013; 12:3529-46. [DOI: 10.1021/pr400431b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Valeria Pallotta
- Department of Ecological
and Biological Sciences, University of Tuscia, Largo dell’Università,
snc, 01100 Viterbo, Italy
| | - Angelo D’Alessandro
- Department of Ecological
and Biological Sciences, University of Tuscia, Largo dell’Università,
snc, 01100 Viterbo, Italy
| | - Sara Rinalducci
- Department of Ecological
and Biological Sciences, University of Tuscia, Largo dell’Università,
snc, 01100 Viterbo, Italy
| | - Lello Zolla
- Department of Ecological
and Biological Sciences, University of Tuscia, Largo dell’Università,
snc, 01100 Viterbo, Italy
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24
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de Moraes MC, Ducati RG, Donato AJ, Basso LA, Santos DS, Cardoso CL, Cass QB. Capillary bioreactors based on human purine nucleoside phosphorylase: A new approach for ligands identification and characterization. J Chromatogr A 2012; 1232:110-5. [DOI: 10.1016/j.chroma.2011.10.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Revised: 10/19/2011] [Accepted: 10/20/2011] [Indexed: 11/27/2022]
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25
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Zhang Y, Zwart PH, Ealick SE. A corrected space group for Sulfolobus sulfataricus 5'-deoxy-5'-methylthioadenosine phosphorylase II. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:249-52. [PMID: 22349226 DOI: 10.1107/s0907444911051699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 11/30/2011] [Indexed: 11/10/2022]
Abstract
5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP) catalyzes the phosphorolytic cleavage of 5'-deoxy-5'-methylthioadenosine (MTA), a byproduct of polyamine biosynthesis. The Sulfolobus sulfataricus genome encodes two MTAPs. SsMTAP I has broad substrate specifity, accepting guanosine, inosine, adenosine and MTA, while SsMTAP II is specific for MTA. SsMTAP I forms a donut-shaped hexamer, while SsMTAP II is a hexamer formed from trimers packed face to face. The structure of SsMTAP II was originally determined in space group P1 (PDB entry 2a8y) and showed R32 pseudosymmetry. Post-analysis using phenix.xtriage showed that the correct space group is C2. Here, the structure refined in space group C2 is reported and the factors that initially led to the incorrect space-group assignment are discussed.
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Affiliation(s)
- Yang Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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26
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Helliwell JR. The evolution of synchrotron radiation and the growth of its importance in crystallography. CRYSTALLOGR REV 2012. [DOI: 10.1080/0889311x.2011.631919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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27
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Cacciapuoti G, Marabotti A, Fuccio F, Porcelli M. Unraveling the structural and functional differences between purine nucleoside phosphorylase and 5′-deoxy-5′-methylthioadenosine phosphorylase from the archaeon Pyrococcus furiosus. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1358-66. [DOI: 10.1016/j.bbapap.2011.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/17/2011] [Accepted: 06/01/2011] [Indexed: 10/18/2022]
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28
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Cloning, purification and characterisation of a recombinant purine nucleoside phosphorylase from Bacillus halodurans Alk36. Extremophiles 2010; 14:185-92. [PMID: 20063024 PMCID: PMC2832885 DOI: 10.1007/s00792-009-0297-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 12/16/2009] [Indexed: 11/07/2022]
Abstract
A purine nucleoside phosphorylase from the alkaliphile Bacillus halodurans Alk36 was cloned and overexpressed in Escherichia coli. The enzyme was purified fivefold by membrane filtration and ion exchange. The purified enzyme had a Vmax of 2.03 × 10−9 s −1 and a Km of 206 μM on guanosine. The optimal pH range was between 5.7 and 8.4 with a maximum at pH 7.0. The optimal temperature for activity was 70°C and the enzyme had a half life at 60°C of 20.8 h.
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29
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Paul D, O'Leary SE, Rajashankar K, Bu W, Toms A, Settembre EC, Sanders JM, Begley TP, Ealick SE. Glycal formation in crystals of uridine phosphorylase. Biochemistry 2010; 49:3499-509. [PMID: 20364833 PMCID: PMC2857653 DOI: 10.1021/bi902073b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Uridine phosphorylase is a key enzyme in the pyrimidine salvage pathway. This enzyme catalyzes the reversible phosphorolysis of uridine to uracil and ribose 1-phosphate (or 2'-deoxyuridine to 2'-deoxyribose 1-phosphate). Here we report the structure of hexameric Escherichia coli uridine phosphorylase treated with 5-fluorouridine and sulfate and dimeric bovine uridine phosphorylase treated with 5-fluoro-2'-deoxyuridine or uridine, plus sulfate. In each case the electron density shows three separate species corresponding to the pyrimidine base, sulfate, and a ribosyl species, which can be modeled as a glycal. In the structures of the glycal complexes, the fluorouracil O2 atom is appropriately positioned to act as the base required for glycal formation via deprotonation at C2'. Crystals of bovine uridine phosphorylase treated with 2'-deoxyuridine and sulfate show intact nucleoside. NMR time course studies demonstrate that uridine phosphorylase can catalyze the hydrolysis of the fluorinated nucleosides in the absence of phosphate or sulfate, without the release of intermediates or enzyme inactivation. These results add a previously unencountered mechanistic motif to the body of information on glycal formation by enzymes catalyzing the cleavage of glycosyl bonds.
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Affiliation(s)
- Debamita Paul
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Seán E. O'Leary
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
- Department of Chemistry, Texas A&M University, College Station, TX 77842, USA
| | - Kanagalaghatta Rajashankar
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
- NE-CAT, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Weiming Bu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Angela Toms
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Ethan C. Settembre
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Jennie M. Sanders
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Tadhg P. Begley
- Department of Chemistry, Texas A&M University, College Station, TX 77842, USA
| | - Steven E. Ealick
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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30
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Kang YN, Zhang Y, Allan PW, Parker WB, Ting JW, Chang CY, Ealick SE. Structure of grouper iridovirus purine nucleoside phosphorylase. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2010; 66:155-62. [PMID: 20124695 DOI: 10.1107/s0907444909048276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 11/13/2009] [Indexed: 11/10/2022]
Abstract
Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of purine ribonucleosides to the corresponding free bases and ribose 1-phosphate. The crystal structure of grouper iridovirus PNP (givPNP), corresponding to the first PNP gene to be found in a virus, was determined at 2.4 A resolution. The crystals belonged to space group R3, with unit-cell parameters a = 193.0, c = 105.6 A, and contained four protomers per asymmetric unit. The overall structure of givPNP shows high similarity to mammalian PNPs, having an alpha/beta structure with a nine-stranded mixed beta-barrel flanked by a total of nine alpha-helices. The predicted phosphate-binding and ribose-binding sites are occupied by a phosphate ion and a Tris molecule, respectively. The geometrical arrangement and hydrogen-bonding patterns of the phosphate-binding site are similar to those found in the human and bovine PNP structures. The enzymatic activity assay of givPNP on various substrates revealed that givPNP can only accept 6-oxopurine nucleosides as substrates, which is also suggested by its amino-acid composition and active-site architecture. All these results suggest that givPNP is a homologue of mammalian PNPs in terms of amino-acid sequence, molecular mass, substrate specificity and overall structure, as well as in the composition of the active site.
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Affiliation(s)
- You-Na Kang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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31
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Afshar S, Olafsen T, Wu AM, Morrison SL. Characterization of an engineered human purine nucleoside phosphorylase fused to an anti-her2/neu single chain Fv for use in ADEPT. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2009; 28:147. [PMID: 19958550 PMCID: PMC2799393 DOI: 10.1186/1756-9966-28-147] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 12/03/2009] [Indexed: 11/26/2022]
Abstract
Background Antibody Directed Enzyme Prodrug Therapy (ADEPT) can be used to generate cytotoxic agents at the tumor site. To date non-human enzymes have mainly been utilized in ADEPT. However, these non-human enzymes are immunogenic limiting the number of times that ADEPT can be administered. To overcome the problem of immunogenicity, a fully human enzyme, capable of converting a non-toxic prodrug to cytotoxic drug was developed and joined to a human tumor specific scFv yielding a fully human targeting agent. Methods A double mutant of human purine nucleoside phosphorylase (hDM) was developed which unlike the human enzyme can cleave adenosine-based prodrugs. For tumor-specific targeting, hDM was fused to the human anti-HER2/neu single chain Fv (scFv), C6 MH3B1. Enzymatic activity of hDM with its natural substrates and prodrugs was determined using spectrophotomeric approaches. A cell proliferation assay was used to assess the cytotoxicity generated following conversion of prodrug to drug as a result of enzymatic activity of hDM. Affinity of the targeting scFv, C6 MH3B1 fused to hDM to Her2/neu was confirmed using affinity chromatography, surface plasmon resonance, and flow-cytometry. Results In vitro hDM-C6 MH3B1 binds specifically to HER2/neu expressing tumor cells and localizes hDM to tumor cells, where the enzymatic activity of hDM-C6 MH3B1, but not the wild type enzyme, results in phosphorolysis of the prodrug, 2-fluoro-2'-deoxyadenosine to the cytotoxic drug 2-fluoroadenine (F-Ade) causing inhibition of tumor cell proliferation. Significantly, the toxic small drug diffuses through the cell membrane of HER2/neu expressing cells as well as cells that lack the expression of HER2/neu, causing a bystander effect. F-Ade is toxic to cells irrespective of their growth rate; therefore, both the slowly dividing tumor cells and the non-dividing neighboring stromal cells that support tumor growth should be killed. Analysis of potential novel MHCII binding peptides resulting from fusion of hDM to C6 MH3B1 and the two mutations in hDM, and of the structure of hDM compared to the wild-type enzyme suggests that hDM-C6 MH3B1 should exhibit minimal immunogenicity in humans. Conclusion hDM-C6 MH3B1 constitutes a novel human based protein that addresses some of the limitations of ADEPT that currently preclude its successful use in the clinic.
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Affiliation(s)
- Sepideh Afshar
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, 247 BSRB, 615 Charles E, Young East, Los Angeles, 90095, USA.
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Hou QM, Liu X, Brostromer E, Li LF, Su XD. Preliminary crystallographic studies of purine nucleoside phosphorylase from the cariogenic pathogen Streptococcus mutans. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:1289-91. [PMID: 20054131 PMCID: PMC2802883 DOI: 10.1107/s1744309109045059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Accepted: 10/28/2009] [Indexed: 11/10/2022]
Abstract
The punA gene of the cariogenic pathogen Streptococcus mutans encodes purine nucleoside phosphorylase (PNP), which is a pivotal enzyme in the nucleotide-salvage pathway, catalyzing the phosphorolysis of purine nucleosides to generate purine bases and alpha-ribose 1-phosphate. In the present work, the PNP protein was expressed in Escherichia coli strain BL21 (DE3) in a soluble form at a high level. After purification of the PNP enzyme, the protein was crystallized using the sitting-drop vapour-diffusion technique; the crystals diffracted to 1.6 A resolution at best. The crystals belonged to space group H3, with unit-cell parameters a = b = 113.0, c = 60.1 A.
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Affiliation(s)
- Qiao-Ming Hou
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Xiang Liu
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Erik Brostromer
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Lan-Fen Li
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Xiao-Dong Su
- Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People’s Republic of China
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A novel mutation in purine nucleoside phosphorylase in a child with normal uric acid levels. Clin Biochem 2009; 42:1725-7. [DOI: 10.1016/j.clinbiochem.2009.08.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 08/03/2009] [Accepted: 08/19/2009] [Indexed: 11/22/2022]
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Afshar S, Asai T, Morrison SL. Humanized ADEPT comprised of an engineered human purine nucleoside phosphorylase and a tumor targeting peptide for treatment of cancer. Mol Cancer Ther 2009; 8:185-93. [PMID: 19139128 DOI: 10.1158/1535-7163.mct-08-0652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Immunogenicity caused by the use of nonhuman enzymes in antibody-directed enzyme prodrug therapy has limited its clinical application. To overcome this problem, we have developed a mutant human purine nucleoside phosphorylase, which, unlike the wild-type enzyme, accepts (deoxy)adenosine-based prodrugs as substrates. Among the different mutants of human purine nucleoside phosphorylase tested, a double mutant with amino acid substitutions E201Q:N243D (hDM) is the most efficient in cleaving (deoxy)adenosine-based prodrugs. Although hDM is capable of using multiple prodrugs as substrates, it is most effective at cleaving 2-fluoro-2'-deoxyadenosine to a cytotoxic drug. To target hDM to the tumor site, the enzyme was fused to an anti-HER-2/neu peptide mimetic (AHNP). Treatment of HER-2/neu-expressing tumor cells with hDM-AHNP results in cellular localization of enzyme activity. As a consequence, harmless prodrug is converted to a cytotoxic drug in the vicinity of the tumor cells, resulting in tumor cell apoptosis. Unlike the nonhuman enzymes, the hDM should have minimal immunogenicity when used in antibody-directed enzyme prodrug therapy, thus providing a novel promising therapeutic agent for the treatment of tumors.
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Affiliation(s)
- Sepideh Afshar
- Department of Microbiology, Immunology, and Molecular Genetics, University of California-Los Angeles, 615 Charles E. Young Drive East, 247 BSRB, Los Angeles, CA 90095, USA.
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35
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Todorova NA, Schwarz FP. Effect of the phosphate substrate on drug-inhibitor binding to human purine nucleoside phosphorylase. Arch Biochem Biophys 2008; 480:122-31. [DOI: 10.1016/j.abb.2008.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 08/26/2008] [Accepted: 10/07/2008] [Indexed: 11/30/2022]
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36
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Timmers LFSM, Caceres RA, Vivan AL, Gava LM, Dias R, Ducati RG, Basso LA, Santos DS, de Azevedo WF. Structural studies of human purine nucleoside phosphorylase: Towards a new specific empirical scoring function. Arch Biochem Biophys 2008; 479:28-38. [DOI: 10.1016/j.abb.2008.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 08/20/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
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37
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Fu W, Lan H, Liang S, Gao T, Ren D. Suicide gene/prodrug therapy using salmonella-mediated delivery of Escherichia coli purine nucleoside phosphorylase gene and 6-methoxypurine 2'-deoxyriboside in murine mammary carcinoma 4T1 model. Cancer Sci 2008; 99:1172-9. [PMID: 18429958 PMCID: PMC11158249 DOI: 10.1111/j.1349-7006.2008.00808.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 02/18/2008] [Accepted: 02/20/2008] [Indexed: 11/26/2022] Open
Abstract
Attenuated salmonella have been reported to be capable of both selectively growing in tumors and expressing exogenous genes for tumor-targeted therapy. As 6-methoxypurine 2'-deoxyriboside (MoPdR) is similar to 6-methylpurine 2'-deoxyriboside in structure, we aimed to evaluate the antitumoral effect of the Escherichia coli purine nucleoside phosphorylase (ePNP) gene, using an attenuated salmonella-mediated delivery system, in combination with MoPdR. A novel mutant serovar Typhimurium (SC36) was used to carry the pEGFP-C1-ePNP vector that contains an enhanced green fluorescent protein and an ePNP gene under the control of the cytomegalovirus promoter. The function of the ePNP expression vector was confirmed in vitro using the enzymic conversion of MoPdR into methoxypurine. We also observed a high bystander effect induced by the ePNP/MoPdR system with a very low proportion (1%) of ePNP-positive cells and 5 microg/mL MoPdR, although the growth of parental cells was affected appreciably by MoPdR. The killing effect and increased apoptosis induced by SC36 carrying the ePNP expression vector (SC/ePNP) were detected by cytotoxicity assay and propidium iodide staining flow cytometry analysis, in combination with MoPdR. SC/ePNP was given orally to mice bearing mammary carcinomas, and its antitumor effect was evaluated. SC/ePNP plus MoPdR significantly inhibited tumor growth by approximately 86.6-88.7% and prolonged the survival of tumor-hosting mice. Our data support the view that MoPdR combined with the ePNP gene could be used in gene-directed enzyme prodrug therapy. Attenuated salmonella could be a promising strategy to improve ePNP/MoPdR bystander killing due to its preferential accumulation and anticancer activity in tumors.
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MESH Headings
- Animals
- Apoptosis/physiology
- Blotting, Western
- Bystander Effect
- Caspase 3/metabolism
- Cell Proliferation
- Combined Modality Therapy
- Escherichia coli/enzymology
- Female
- Genes, Transgenic, Suicide
- Genetic Therapy
- Genetic Vectors
- Green Fluorescent Proteins/genetics
- Humans
- Mammary Neoplasms, Experimental/drug therapy
- Mammary Neoplasms, Experimental/pathology
- Mammary Neoplasms, Experimental/therapy
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Prodrugs/therapeutic use
- Promoter Regions, Genetic
- Purine Nucleosides/therapeutic use
- Purine-Nucleoside Phosphorylase/genetics
- Salmonella/genetics
- Transcription, Genetic
- Tumor Cells, Cultured
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Wei Fu
- The State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, 220 Han Dan Road, Shanghai 200433, China
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38
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Fu W, Lan H, Li S, Han X, Gao T, Ren D. Synergistic antitumor efficacy of suicide/ePNP gene and 6-methylpurine 2'-deoxyriboside via Salmonella against murine tumors. Cancer Gene Ther 2008; 15:474-84. [PMID: 18437183 DOI: 10.1038/cgt.2008.19] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Some anaerobes and facultative anaerobes have been used in tumor-specific gene therapy by reason of their selective growth in tumors. In this work, we aimed to evaluate the anticancer efficacy of attenuated Salmonella typhimurium as a carrier to deliver the Escherichia coli purine nucleoside phosphorylase (ePNP) gene for GDEPT (gene-directed enzyme-prodrug therapy). A live attenuated purine-auxotrophic strain of S. typhimurium (SC36) was used to carry the pEGFP-C1-ePNP vector that contains a green fluorescent protein (GFP) and an ePNP gene under the control of the human cytomegalovirus (CMV) promoter. The function of the ePNP expression vector was confirmed in vitro using the enzymic conversion of 6-methylpurine 2'-deoxyriboside (MePdR) into 6-methylpurine. We also observed a high bystander effect induced by the ePNP/MePdR system with a very low proportion (1%) of ePNP-positive cells. The killing effect and increased apoptosis induced by SC/ePNP (SC36 carrying the ePNP expression vector) infection were detected by cytotoxicity assay and PI staining flow cytometry analysis, in combination with MePdR administration. Furthermore, SC/ePNP was administered orally into mice bearing melanomas or pulmonary tumors, and its anti-tumor effect was evaluated. When the tumor was huge (500 mm(3)) at the beginning of MePdR administration, SC/ePNP plus MepdR significantly inhibited tumor growth by about 59-80% and prolonged survival of mice. Complete tumor regression and long-term cure were achieved by MePdR administration, even when the tumor was large (100 mm(3)) at the beginning of MePdR treatment. Our data support a hopeful view that tumor-targeting SC36 could improve antitumor efficacy of the ePNP/MePdR system due to its preferential accumulation and anticancer activity in tumors.
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Affiliation(s)
- W Fu
- State Key Lab of Genetic Engineering, Department of Genetics, Fudan University, Shanghai, China
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39
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Ghanem M, Saen-oon S, Zhadin N, Wing C, Cahill SM, Schwartz SD, Callender R, Schramm VL. Tryptophan-free human PNP reveals catalytic site interactions. Biochemistry 2008; 47:3202-15. [PMID: 18269249 DOI: 10.1021/bi702491d] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human purine nucleoside phosphorylase (PNP) is a homotrimer, containing three nonconserved tryptophan residues at positions 16, 94, and 178, all remote from the catalytic site. The Trp residues were replaced with Tyr to produce Trp-free PNP (Leuko-PNP). Leuko-PNP showed near-normal kinetic properties. It was used (1) to determine the tautomeric form of guanine that produces strong fluorescence when bound to PNP, (2) for thermodynamic binding analysis of binary and ternary complexes with substrates, (3) in temperature-jump perturbation of complexes for evidence of multiple conformational complexes, and (4) to establish the ionization state of a catalytic site tyrosine involved in phosphate nucleophile activation. The (13)C NMR spectrum of guanine bound to Leuko-PNP, its fluorescent properties, and molecular orbital electronic transition analysis establish that its fluorescence originates from the lowest singlet excited state of the N1H, 6-keto, N7H guanine tautomer. Binding of guanine and phosphate to PNP and Leuko-PNP are random, with decreased affinity for formation of ternary complexes. Pre-steady-state kinetics and temperature-jump studies indicate that the ternary complex (enzyme-substrate-phosphate) forms in single binding steps without kinetically significant protein conformational changes as monitored by guanine fluorescence. Spectral changes of Leuko-PNP upon phosphate binding establish that the hydroxyl of Tyr88 is not ionized to the phenolate anion when phosphate is bound. A loop region (residues 243-266) near the purine base becomes highly ordered upon substrate/inhibitor binding. A single Trp residue was introduced into the catalytic loop of Leuko-PNP (Y249W-Leuko-PNP) to determine effects on catalysis and to introduce a fluorescence catalytic site probe. Although Y249W-Leuko-PNP is highly fluorescent and catalytically active, substrate binding did not perturb the fluorescence. Thermodynamic boxes, constructed to characterize the binding of phosphate, guanine, and hypoxanthine to native, Leuko-, and Y249W-Leuko-PNPs, establish that Leuko-PNP provides a versatile protein scaffold for introduction of specific Trp catalytic site probes.
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Affiliation(s)
- Mahmoud Ghanem
- Departments of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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40
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Evans GB, Furneaux RH, Greatrex B, Murkin AS, Schramm VL, Tyler PC. Azetidine Based Transition State Analogue Inhibitors ofN-Ribosyl Hydrolases and Phosphorylases. J Med Chem 2008; 51:948-56. [DOI: 10.1021/jm701265n] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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41
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Rinaldo-Matthis A, Murkin AS, Ramagopal UA, Clinch K, Mee SPH, Evans GB, Tyler PC, Furneaux RH, Almo SC, Schramm VL. L-Enantiomers of transition state analogue inhibitors bound to human purine nucleoside phosphorylase. J Am Chem Soc 2007; 130:842-4. [PMID: 18154341 DOI: 10.1021/ja710733g] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human purine nucleoside phosphorylase (PNP) was crystallized with transition-state analogue inhibitors Immucillin-H and DADMe-Immucillin-H synthesized with ribosyl mimics of l-stereochemistry. The inhibitors demonstrate that major driving forces for tight binding of these analogues are the leaving group interaction and the cationic mimicry of the transition state, even though large geometric changes occur with d-Immucillins and l-Immucillins bound to human PNP.
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Affiliation(s)
- Agnes Rinaldo-Matthis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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42
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Modrak-Wójcik A, Kirilenko A, Shugar D, Kierdaszuk B. Role of ionization of the phosphate cosubstrate on phosphorolysis by purine nucleoside phosphorylase (PNP) of bacterial (E. coli) and mammalian (human) origin. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:153-64. [PMID: 17639373 DOI: 10.1007/s00249-007-0205-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2007] [Revised: 05/31/2007] [Accepted: 06/12/2007] [Indexed: 10/23/2022]
Abstract
Kinetics of the reactions of purine nucleoside phosphorylases (PNP) from E. coli (PNP-I, the product of the deoD gene) and human erythrocytes with their natural substrates guanosine (Guo), inosine (Ino), a substrate analogue N(7)-methylguanosine (m(7)Guo), and orthophosphate (P(i), natural cosubstrate) and its thiophosphate analogue (SP(i)), found to be a weak cosubstrate, have been studied in the pH range 5-8. In this pH range Guo and Ino exist predominantly in the neutral forms (pK(a) 9.2 and 8.8); m(7)Guo consists of an equilibrium mixture of the cationic and zwitterionic forms (pK(a) 7.0); and P(i) and SP(i) exhibit equilibria between monoanionic and dianionic forms (pK(a) 6.7 and 5.4, respectively). The phosphorolysis of m(7)Guo (at saturated concentration) with both enzymes exhibits Michaelis kinetics with SP(i), independently of pH. With P(i), the human enzyme shows Michaelis kinetics only at pH approximately 5. However, in the pH range 5-8 for the bacterial enzyme, and 6-8 for the human enzyme, enzyme kinetics with P(i) are best described by a model with high- and low-affinity states of the enzymes, denoted as enzyme-substrate complexes with one or two active sites occupied by P(i), characterized by two sets of enzyme-substrate dissociation constants (apparent Michaelis constants, K (m1) and K (m2)) and apparent maximal velocities (V (max1) and V (max2)). Their values, obtained from non-linear least-squares fittings of the Adair equation, were typical for negative cooperativity of both substrate binding (K (m1) < K (m2)) and enzyme kinetics (V (max1)/K (m1) > V (max2)/K (m2)). Comparison of the pH-dependence of the substrate properties of P(i) versus SP(i) points to both monoanionic and dianionic forms of P(i) as substrates, with a marked preference for the dianionic species in the pH range 5-8, where the population of the P(i) dianion varies from 2 to 95%, reflected by enzyme efficiency three orders of magnitude higher at pH 8 than that at pH 5. This is accompanied by an increase in negative cooperativity, characterized by a decrease in the Hill coefficient from n (H) approximately 1 to n (H) approximately 0.7 for Guo with the human enzyme, and to n (H) approximately 0.7 and 0.5 for m(7)Guo with the E. coli and human enzymes, respectively. Possible mechanisms of cooperativity are proposed. Attention is drawn to the substrate properties of SP(i) in relation to its structure.
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Affiliation(s)
- Anna Modrak-Wójcik
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
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43
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Zhang Y, Porcelli M, Cacciapuoti G, Ealick SE. The Crystal Structure of 5′-Deoxy-5′-methylthioadenosine Phosphorylase II from Sulfolobus solfataricus, a Thermophilic Enzyme Stabilized by Intramolecular Disulfide Bonds. J Mol Biol 2006; 357:252-62. [PMID: 16414070 DOI: 10.1016/j.jmb.2005.12.040] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 12/08/2005] [Accepted: 12/11/2005] [Indexed: 11/25/2022]
Abstract
The crystal structure of Sulfolobus solfataricus 5'-deoxy-5'-methylthioadenosine phosphorylase II (SsMTAPII) in complex with 5'-deoxy-5'-methylthioadenosine (MTA) and sulfate was determined to 1.45A resolution. The hexameric structure of SsMTAPII is a dimer-of-trimers with one active site per monomer. The oligomeric assembly of the trimer and the monomer topology of SsMTAPII are almost identical with trimeric human 5'-deoxy-5'-methylthioadenosine phosphorylase (hMTAP). SsMTAPII is the first reported hexameric member in the trimeric class of purine nucleoside phosphorylase (PNP) from Archaea. Unlike hMTAP, which is highly specific for MTA, SsMTAPII also accepts adenosine as a substrate. The residues at the active sites of SsMTAPII and hMTAP are almost identical. The broad substrate specificity of SsMTAPII may be due to the flexibility of the C-terminal loop. SsMTAPII is extremely thermoactive and thermostable. The three-dimensional structure of SsMTAPII suggests that the unique dimer-of-trimers quaternary structure, a CXC motif at the C terminus, and two pairs of intrasubunit disulfide bridges may play an important role in its thermal stability.
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Affiliation(s)
- Yan Zhang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-1301, USA
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44
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Silva RG, Pereira JH, Canduri F, de Azevedo WF, Basso LA, Santos DS. Kinetics and crystal structure of human purine nucleoside phosphorylase in complex with 7-methyl-6-thio-guanosine. Arch Biochem Biophys 2005; 442:49-58. [PMID: 16154528 DOI: 10.1016/j.abb.2005.07.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 07/25/2005] [Accepted: 07/27/2005] [Indexed: 11/26/2022]
Abstract
Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of nucleosides and deoxynucleosides, generating ribose 1-phosphate and the purine base, which is an important step of purine catabolism pathway. The lack of such an activity in humans, owing to a genetic disorder, causes T-cell impairment, and drugs that inhibit this enzyme may have the potential of being utilized as modulators of the immunological system to treat leukemia, autoimmune diseases, and rejection in organ transplantation. Here, we describe kinetics and crystal structure of human PNP in complex with 7-methyl-6-thio-guanosine, a synthetic substrate, which is largely used in activity assays. Analysis of the structure identifies different protein conformational changes upon ligand binding, and comparison of kinetic and structural data permits an understanding of the effects of atomic substitution on key positions of the synthetic substrate and their consequences to enzyme binding and catalysis. Such knowledge may be helpful in designing new PNP inhibitors.
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Affiliation(s)
- Rafael G Silva
- Centro de Pesquisas em Biologia Molecular e Funcional, Instituto de Pesquisas Biomédicas, PUCRS, Porto Alegre, RS, Brazil
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45
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Lee JE, Smith GD, Horvatin C, Huang DJT, Cornell KA, Riscoe MK, Howell PL. Structural snapshots of MTA/AdoHcy nucleosidase along the reaction coordinate provide insights into enzyme and nucleoside flexibility during catalysis. J Mol Biol 2005; 352:559-74. [PMID: 16109423 DOI: 10.1016/j.jmb.2005.07.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 07/08/2005] [Accepted: 07/10/2005] [Indexed: 11/27/2022]
Abstract
MTA/AdoHcy nucleosidase (MTAN) irreversibly hydrolyzes the N9-C1' bond in the nucleosides, 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (AdoHcy) to form adenine and the corresponding thioribose. MTAN plays a vital role in metabolic pathways involving methionine recycling, biological methylation, polyamine biosynthesis, and quorum sensing. Crystal structures of a wild-type (WT) MTAN complexed with glycerol, and mutant-enzyme and mutant-product complexes have been determined at 2.0A, 2.0A, and 2.1A resolution, respectively. The WT MTAN-glycerol structure provides a purine-free model and in combination with the previously solved thioribose-free MTAN-ADE structure, we now have separate apo structures for both MTAN binding subsites. The purine and thioribose-free states reveal an extensive enzyme-immobilized water network in their respective binding subsites. The Asp197Asn MTAN-MTA and Glu12Gln MTAN-MTR.ADE structures are the first enzyme-substrate and enzyme-product complexes reported for MTAN, respectively. These structures provide representative snapshots along the reaction coordinate and allow insight into the conformational changes of the enzyme and the nucleoside substrate. A "catalytic movie" detailing substrate binding, catalysis, and product release is presented.
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Affiliation(s)
- Jeffrey E Lee
- Structural Biology and Biochemistry, Research Institute, Hospital for Sick Children, 555 University Avenue, Toronto, Ont., Canada
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46
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Basso LA, da Silva LHP, Fett-Neto AG, de Azevedo WF, Moreira IDS, Palma MS, Calixto JB, Astolfi Filho S, dos Santos RR, Soares MBP, Santos DS. The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases: a review. Mem Inst Oswaldo Cruz 2005; 100:475-506. [PMID: 16302058 DOI: 10.1590/s0074-02762005000600001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The modern approach to the development of new chemical entities against complex diseases, especially the neglected endemic diseases such as tuberculosis and malaria, is based on the use of defined molecular targets. Among the advantages, this approach allows (i) the search and identification of lead compounds with defined molecular mechanisms against a defined target (e.g. enzymes from defined pathways), (ii) the analysis of a great number of compounds with a favorable cost/benefit ratio, (iii) the development even in the initial stages of compounds with selective toxicity (the fundamental principle of chemotherapy), (iv) the evaluation of plant extracts as well as of pure substances. The current use of such technology, unfortunately, is concentrated in developed countries, especially in the big pharma. This fact contributes in a significant way to hamper the development of innovative new compounds to treat neglected diseases. The large biodiversity within the territory of Brazil puts the country in a strategic position to develop the rational and sustained exploration of new metabolites of therapeutic value. The extension of the country covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these scenarios. Chemical diversity is also driven by these forces, in an attempt to best fit the plant communities to the particular abiotic stresses, fauna, and microbes that co-exist with them. Certain areas of vegetation (Amazonian Forest, Atlantic Forest, Araucaria Forest, Cerrado-Brazilian Savanna, and Caatinga) are rich in species and types of environments to be used to search for natural compounds active against tuberculosis, malaria, and chronic-degenerative diseases. The present review describes some strategies to search for natural compounds, whose choice can be based on ethnobotanical and chemotaxonomical studies, and screen for their ability to bind to immobilized drug targets and to inhibit their activities. Molecular cloning, gene knockout, protein expression and purification, N-terminal sequencing, and mass spectrometry are the methods of choice to provide homogeneous drug targets for immobilization by optimized chemical reactions. Plant extract preparations, fractionation of promising plant extracts, propagation protocols and definition of in planta studies to maximize product yield of plant species producing active compounds have to be performed to provide a continuing supply of bioactive materials. Chemical characterization of natural compounds, determination of mode of action by kinetics and other spectroscopic methods (MS, X-ray, NMR), as well as in vitro and in vivo biological assays, chemical derivatization, and structure-activity relationships have to be carried out to provide a thorough knowledge on which to base the search for natural compounds or their derivatives with biological activity.
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Affiliation(s)
- Luiz Augusto Basso
- Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, 90619-900, Brasil.
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47
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Pereira HD, Franco GR, Cleasby A, Garratt RC. Structures for the potential drug target purine nucleoside phosphorylase from Schistosoma mansoni causal agent of schistosomiasis. J Mol Biol 2005; 353:584-99. [PMID: 16182308 DOI: 10.1016/j.jmb.2005.08.045] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2005] [Revised: 08/19/2005] [Accepted: 08/19/2005] [Indexed: 11/15/2022]
Abstract
Despite the availability of effective chemotherapy, schistosomiasis continues to be one of the major parasitic infections to affect the human population worldwide. Currently, little is known of the structural biology of the parasites that are responsible for the disease and few attempts have been made to develop second generation drugs, which may become essential if resistance to those currently available becomes an issue. Here, we describe three crystal structures for the enzyme purine nucleoside phosphorylase (PNP) from Schistosoma mansoni, a component of the purine salvage pathway. PNP is known to be essential for the recovery of purine bases and nucleosides in schistosomes, due to an absence of the enzymes for de novo synthesis, making it a sensitive point in the parasite's metabolism. In all three structures reported here, acetate occupies part of the base-binding site and is directly bound to the conserved glutamic acid at position 203. One of the structures presents the crystallization additive sulfobetaine 195 (NDSB195) occupying simultaneously the ribose and phosphate binding sites, whilst a second presents only phosphate in the latter. The observation of sulfobetaine specifically bound to the protein active site was unexpected and is unique to this structure as far as we are aware. Considerable flexibility is observed in the active site, principally due to variable structural disorder in the regions centered on residues 64 and 260. This conformational plasticity extends to the way in which both NDSB195 and phosphate bind to the individual monomers of the trimeric structure reported here. Differences between the parasite and human enzymes are limited principally to the base-binding site, where the substitution of V245 in the mammalian enzymes by S247 introduces additional hydrogen bonding potential to the site. This is satisfied in the structures described here by a water molecule whose presence is normally observed only in complexes with 6-oxopurines. Residue Y202, which replaces F200 in human PNP, is able to reach over the ribose-binding site to interact with H259 and is predicted to form an additional hydrogen bond with the 5' hydroxyl of nucleoside substrates.
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Affiliation(s)
- Humberto D'Muniz Pereira
- Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos-SP, Brazil
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48
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Bharara S, Sorscher EJ, Gillespie GY, Lindsey JR, Hong JS, Curlee KV, Allan PW, Gadi VK, Alexander SA, Secrist JA, Parker WB, Waud WR. Antibiotic-mediated chemoprotection enhances adaptation of E. coli PNP for herpes simplex virus-based glioma therapy. Hum Gene Ther 2005; 16:339-47. [PMID: 15812229 DOI: 10.1089/hum.2005.16.339] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The E. coli PNP suicide gene sensitizes solid tumors to nucleoside prodrugs, such as 6-methylpurine-2'-deoxyriboside (MeP-dR). In this study using lentiviral, MuLv, and HSV-based gene transfer, we quantified thresholds for inhibition of tumor growth and bystander killing by E. coli PNP and tested the role of intestinal flora in this process. Regressions of human glioma tumors following retroviral transduction exhibited dose dependence on both the level of PNP expression and the dose of MeP-dR administered, including strong tumor inhibition when 90-99% bystander cells comprised the tumor mass. A replication competent, non-neurovirulent herpes simplex virus (HSV) deficient in both copies of the gamma-1 34.5 gene was next engineered to express E. coli PNP under the egr-1 promoter (HSV-PNP). HSV-PNP injected intratumorally (17 million pfu/0.05 ml) in nude mice bearing 300 mg human glioma flank tumors produced a delay in tumor growth (approximately 24 days delay to one doubling). MeP-dR treatment after antibiotic therapy (to eliminate enteric flora encoding PNP enzymes) resulted in antitumor enhancement, with arrest of tumor growth (delay to doubling >50 days). Bystander killing of the magnitude described here has been difficult to accomplish with other suicide genes, such as HSV-tk or cytosine deaminase. The results establish a model for applying E. coli PNP to HSV treatment of glioma.
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Affiliation(s)
- Suman Bharara
- Department of Surgery, University of Alabama at Birmingham, AL 35294, USA
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Cacciapuoti G, Moretti MA, Forte S, Brio A, Camardella L, Zappia V, Porcelli M. Methylthioadenosine phosphorylase from the archaeon Pyrococcus furiosus. Mechanism of the reaction and assignment of disulfide bonds. ACTA ACUST UNITED AC 2005; 271:4834-44. [PMID: 15606771 DOI: 10.1111/j.1432-1033.2004.04449.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The extremely heat-stable 5'-methylthioadenosine phosphorylase from the hyperthermophilic archaeon Pyrococcus furiosus was cloned, expressed to high levels in Escherichia coli, and purified to homogeneity by heat precipitation and affinity chromatography. The recombinant enzyme was subjected to a kinetic analysis including initial velocity and product inhibition studies. The reaction follows an ordered Bi-Bi mechanism and phosphate binding precedes nucleoside binding in the phosphorolytic direction. 5'-Methylthioadenosine phosphorylase from Pyrococcus furiosus is a hexameric protein with five cysteine residues per subunit. Analysis of the fragments obtained after digestion of the protein alkylated without previous reduction identified two intrasubunit disulfide bridges. The enzyme is very resistant to chemical denaturation and the transition midpoint for guanidinium chloride-induced unfolding was determined to be 3.0 M after 22 h incubation. This value decreases to 2.0 M in the presence of 30 mM dithiothreitol, furnishing evidence that disulfide bonds are needed for protein stability. The guanidinium chloride-induced unfolding is completely reversible as demonstrated by the analysis of the refolding process by activity assays, fluorescence measurements and SDS/PAGE. The finding of multiple disulfide bridges in 5'-methylthioadenosine phosphorylase from Pyrococcus furiosus argues strongly that disulfide bond formation may be a significant molecular strategy for stabilizing intracellular hyperthermophilic proteins.
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Affiliation(s)
- Giovanna Cacciapuoti
- Dipartimento di Biochimica e Biofisica F. Cedrangolo, Seconda Università di Napoli, Naples, Italy.
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50
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Zang Y, Wang WH, Wu SW, Ealick SE, Wang CC. Identification of a subversive substrate of Trichomonas vaginalis purine nucleoside phosphorylase and the crystal structure of the enzyme-substrate complex. J Biol Chem 2005; 280:22318-25. [PMID: 15817485 DOI: 10.1074/jbc.m501843200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trichomonas vaginalis is an anaerobic protozoan parasite that causes trichomoniasis, a common sexually transmitted disease with worldwide impact. One of the pivotal enzymes in its purine salvage pathway, purine nucleoside phosphorylase (PNP), shows physical properties and substrate specificities similar to those of the high molecular mass bacterial PNPs but differing from those of human PNP. While carrying out studies to identify inhibitors of T. vaginalis PNP (TvPNP), we discovered that the nontoxic nucleoside analogue 2-fluoro-2'-deoxyadenosine (F-dAdo) is a "subversive substrate." Phosphorolysis by TvPNP of F-dAdo, which is not a substrate for human PNP, releases highly cytotoxic 2-fluoroadenine (F-Ade). In vitro studies showed that both F-dAdo and F-Ade exert strong inhibition of T. vaginalis growth with estimated IC(50) values of 106 and 84 nm, respectively, suggesting that F-dAdo might be useful as a potential chemotherapeutic agent against T. vaginalis. To understand the basis of TvPNP specificity, the structures of TvPNP complexed with F-dAdo, 2-fluoroadenosine, formycin A, adenosine, inosine, or 2'-deoxyinosine were determined by x-ray crystallography with resolutions ranging from 2.4 to 2.9 A. These studies showed that the quaternary structure, monomer fold, and active site are similar to those of Escherichia coli PNP. The principal active site difference is at Thr-156, which is alanine in E. coli PNP. In the complex of TvPNP with F-dAdo, Thr-156 causes the purine base to tilt and shift by 0.5 A as compared with the binding scheme of F-dAdo in E. coli PNP. The structures of the TvPNP complexes suggest opportunities for further improved subversive substrates beyond F-dAdo.
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Affiliation(s)
- Yang Zang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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