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Hernández-Gómez A, Irisarri I, Fernández-Justel D, Peláez R, Jiménez A, Revuelta JL, Balsera M, Buey RM. GuaB3, an overlooked enzyme in cyanobacteria's toolbox that sheds light on IMP dehydrogenase evolution. Structure 2023; 31:1526-1534.e4. [PMID: 37875114 DOI: 10.1016/j.str.2023.09.014] [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: 07/11/2023] [Revised: 09/05/2023] [Accepted: 09/28/2023] [Indexed: 10/26/2023]
Abstract
IMP dehydrogenase and GMP reductase are enzymes from the same protein family with analogous structures and catalytic mechanisms that have gained attention because of their essential roles in nucleotide metabolism and as potential drug targets. This study focusses on GuaB3, a less-explored enzyme within this family. Phylogenetic analysis uncovers GuaB3's independent evolution from other members of the family and it predominantly occurs in Cyanobacteria. Within this group, GuaB3 functions as a unique IMP dehydrogenase, while its counterpart in Actinobacteria has a yet unknown function. Synechocystis sp. PCC6803 GuaB3 structures demonstrate differences in the active site compared to canonical IMP dehydrogenases, despite shared catalytic mechanisms. These findings highlight the essential role of GuaB3 in Cyanobacteria, provide insights into the diversity and evolution of the IMP dehydrogenase protein family, and reveal a distinctive characteristic in nucleotide metabolism, potentially aiding in combating harmful cyanobacterial blooms-a growing concern for humans and wildlife.
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Affiliation(s)
- Alejandro Hernández-Gómez
- Metabolic Engineering Group, Dpto. Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Iker Irisarri
- Section Phylogenomics, Centre for Molecular Biodiversity Research, Leibniz Institute for the Analysis of Biodiversity Change (LIB), Museum of Nature Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
| | - David Fernández-Justel
- Metabolic Engineering Group, Dpto. Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Rafael Peláez
- Laboratorio de Química Orgánica y Farmacéutica, Dpto. Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Alberto Jiménez
- Metabolic Engineering Group, Dpto. Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - José Luis Revuelta
- Metabolic Engineering Group, Dpto. Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Mónica Balsera
- Department Abiotic Stress, Instituto de Recursos Naturales y Agrobiología (IRNASA-CSIC), Cordel de Merinas 40-52, 37008 Salamanca, Spain
| | - Rubén M Buey
- Metabolic Engineering Group, Dpto. Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
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2
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Dilip H, Purushothaman G, Sharma G, Menon A, Thiruvenkatam V, Kirubakaran S. Mutants of Helicobacter pylori IMPDH: Kinetics and in silico Studies to Determine the Structural and Functional Role of Key Amino Acids. Chem Asian J 2022; 17:e202200125. [PMID: 35293683 DOI: 10.1002/asia.202200125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/14/2022] [Indexed: 11/12/2022]
Abstract
The emergence of antibiotic-resistant strains of Helicobacter pylori necessitates the development of novel therapeutic strategies to fight against its infection. Recently, the enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) has emerged as a promising target to treat bacterial infections due to its crucial role in the de novo purine biosynthesis pathway. The differences between the prokaryotic and eukaryotic IMPDHs, in the NAD + binding domain and flap region, allow the identification of pathogen-specific inhibitors. In the present study, seven point mutants of wild type Helicobacter pylori IMPDH are constructed by site-directed mutagenesis, and characterized using in silico and kinetic studies. Point mutations in the NAD + binding domain and the flap region are shown to impart significant changes in the enzyme's structure and function. In addition, the product inhibition characteristics of the Arg396-Tyr397 dyad (RY dyad) show that both the residues are important for water activation in the reaction. The results obtained are beneficial for the design and development of small molecule inhibitors, capable of species-specific inhibition.
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Affiliation(s)
- Haritha Dilip
- Indian Institute of Technology Gandhinagar, Chemistry, INDIA
| | | | - Gaurav Sharma
- Indian Institute of Technology Gandhinagar, Chemistry, INDIA
| | - Aishwarya Menon
- Indian Institute of Technology Gandhinagar, Bioengineering, INDIA
| | | | - Sivapriya Kirubakaran
- Indian Institute of Technology, Chemistry & Bioengineering, Academic Block 4, 401b, Palaj Campus, 382355, Gandhinagar, INDIA
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3
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Borbone N, Piccialli G, Roviello GN, Oliviero G. Nucleoside Analogs and Nucleoside Precursors as Drugs in the Fight against SARS-CoV-2 and Other Coronaviruses. Molecules 2021; 26:986. [PMID: 33668428 PMCID: PMC7918729 DOI: 10.3390/molecules26040986] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 01/18/2023] Open
Abstract
Coronaviruses (CoVs) are positive-sense RNA enveloped viruses, members of the family Coronaviridae, that cause infections in a broad range of mammals including humans. Several CoV species lead to mild upper respiratory infections typically associated with common colds. However, three human CoV (HCoV) species: Severe Acute Respiratory Syndrome (SARS)-CoV-1, Middle East Respiratory Syndrome (MERS)-CoV, and SARS-CoV-2, are responsible for severe respiratory diseases at the origin of two recent epidemics (SARS and MERS), and of the current COronaVIrus Disease 19 (COVID-19), respectively. The easily transmissible SARS-CoV-2, emerging at the end of 2019 in China, spread rapidly worldwide, leading the World Health Organization (WHO) to declare COVID-19 a pandemic. While the world waits for mass vaccination, there is an urgent need for effective drugs as short-term weapons to combat the SARS-CoV-2 infection. In this context, the drug repurposing approach is a strategy able to guarantee positive results rapidly. In this regard, it is well known that several nucleoside-mimicking analogs and nucleoside precursors may inhibit the growth of viruses providing effective therapies for several viral diseases, including HCoV infections. Therefore, this review will focus on synthetic nucleosides and nucleoside precursors active against different HCoV species, paying great attention to SARS-CoV-2. This work covers progress made in anti-CoV therapy with nucleoside derivatives and provides insight into their main mechanisms of action.
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Affiliation(s)
- Nicola Borbone
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, 80131 Naples, Italy; (N.B.); (G.P.)
| | - Gennaro Piccialli
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 49, 80131 Naples, Italy; (N.B.); (G.P.)
| | | | - Giorgia Oliviero
- Department of Molecular Medicine and Medical Biotechnologies, University of Napoli Federico II, Via Sergio Pansini 5, 80131 Naples, Italy;
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4
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Yu R, Kim Y, Maltseva N, Braunstein P, Joachimiak A, Hedstrom L. Oxanosine Monophosphate Is a Covalent Inhibitor of Inosine 5'-Monophosphate Dehydrogenase. Chem Res Toxicol 2019; 32:456-466. [PMID: 30746940 DOI: 10.1021/acs.chemrestox.8b00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reactive nitrogen species (RNS) are produced during infection and inflammation, and the effects of these agents on proteins, DNA, and lipids are well recognized. In contrast, the effects of RNS damaged metabolites are less appreciated. 5-Amino-3-β-(d-ribofuranosyl)-3 H-imidazo-[4,5- d][1,3]oxazine-7-one (oxanosine) and its nucleotides are products of guanosine nitrosation. Here we demonstrate that oxanosine monophosphate (OxMP) is a potent reversible competitive inhibitor of IMPDH. The value of Ki varies from 50 to 340 nM among IMPDHs from five different organisms. UV spectroscopy and X-ray crystallography indicate that OxMP forms a ring-opened covalent adduct with the active site Cys (E-OxMP*). Unlike the covalent intermediate of the normal catalytic reaction, E-OxMP* does not hydrolyze, but instead recyclizes to OxMP. IMPDH inhibitors block proliferation and can induce apoptosis, so the inhibition of IMPDH by OxMP presents another potential mechanism for RNS toxicity.
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Affiliation(s)
- Runhan Yu
- Department of Chemistry , Brandeis University , Waltham , Massachusetts 02454 , United States
| | - Youngchang Kim
- Structural Biology Center, Biosciences , Argonne National Laboratory , Argonne , Illinois 60439 , United States.,Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering , University of Chicago , Chicago , Illinois 60637 , United States
| | - Natalia Maltseva
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering , University of Chicago , Chicago , Illinois 60637 , United States
| | - Philip Braunstein
- Department of Biochemistry , Brandeis University , Waltham , Massachusetts 02454 , United States
| | - Andrzej Joachimiak
- Structural Biology Center, Biosciences , Argonne National Laboratory , Argonne , Illinois 60439 , United States.,Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering , University of Chicago , Chicago , Illinois 60637 , United States.,Department of Biochemistry and Molecular Biology , University of Chicago , Chicago , Illinois 60557 , United States
| | - Lizbeth Hedstrom
- Department of Chemistry , Brandeis University , Waltham , Massachusetts 02454 , United States.,Department of Biology , Brandeis University , Waltham , Massachusetts 02454 , United States
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5
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Tzoneva G, Dieck CL, Oshima K, Ambesi-Impiombato A, Sánchez-Martín M, Madubata CJ, Khiabanian H, Yu J, Waanders E, Iacobucci I, Sulis ML, Kato M, Koh K, Paganin M, Basso G, Gastier-Foster JM, Loh ML, Kirschner-Schwabe R, Mullighan CG, Rabadan R, Ferrando AA. Clonal evolution mechanisms in NT5C2 mutant-relapsed acute lymphoblastic leukaemia. Nature 2018; 553:511-514. [PMID: 29342136 PMCID: PMC5931372 DOI: 10.1038/nature25186] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 11/30/2017] [Indexed: 01/10/2023]
Abstract
Relapsed acute lymphoblastic leukemia (ALL) is associated with chemotherapy resistance and poor prognosis1. Gain-of-function mutations in the 5′-nucleotidase, cytosolic II (NT5C2) gene induce resistance to 6-mercaptopurine (6-MP) and are selectively present in relapsed ALL2,3. Yet, the mechanisms involved in NT5C2 mutation-driven clonal evolution during leukemia initiation, disease progression and relapse remain unknown. Using a conditional inducible leukemia model, we demonstrate that expression of Nt5c2 p.R367Q, a highly prevalent relapsed-ALL NT5C2 mutation, induces resistance to chemotherapy with 6-MP at the cost of impaired leukemia cell growth and leukemia-initiating cell activity. The loss of fitness phenotype of Nt5c2+/R367Q mutant cells is associated with excess export of purines to the extracellular space and depletion of the intracellular purine nucleotide pool. Consequently, blocking guanosine synthesis via inosine-5′-monophosphate dehydrogenase (IMPDH) inhibition induced increased cytotoxicity against NT5C2-mutant leukemia lymphoblasts. These results identify NT5C2 mutation-associated fitness cost and resistance to chemotherapy as key evolutionary drivers shaping clonal evolution in relapsed ALL and support a role for IMPDH inhibition in the treatment of ALL.
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Affiliation(s)
- Gannie Tzoneva
- Institute for Cancer Genetics, Columbia University, New York, New York 10032, USA
| | - Chelsea L Dieck
- Institute for Cancer Genetics, Columbia University, New York, New York 10032, USA
| | - Koichi Oshima
- Institute for Cancer Genetics, Columbia University, New York, New York 10032, USA
| | | | - Marta Sánchez-Martín
- Institute for Cancer Genetics, Columbia University, New York, New York 10032, USA
| | - Chioma J Madubata
- Department of Systems Biology, Columbia University, New York, New York 10032, USA
| | - Hossein Khiabanian
- Rutgers Cancer Institute, Rutgers University, New Brunswick, New Jersey 08903, USA
| | - Jiangyan Yu
- Princess Maxima Center for Pediatric Oncology, Utrecht, 3584 CT, the Netherlands.,Department of Human Genetics, Radboud University Medical Center and Radboud Institute for Molecular Life Sciences, Nijmegen, 6525 GA, the Netherlands
| | - Esme Waanders
- Princess Maxima Center for Pediatric Oncology, Utrecht, 3584 CT, the Netherlands
| | - Ilaria Iacobucci
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
| | - Maria Luisa Sulis
- Department of Pediatrics, Columbia University Medical Center, New York, New York 10032, USA
| | - Motohiro Kato
- Department of Hematology-Oncology, Saitama Children's Medical Center, Saitama 339-8551, Japan
| | - Katsuyoshi Koh
- Department of Hematology-Oncology, Saitama Children's Medical Center, Saitama 339-8551, Japan
| | - Maddalena Paganin
- Onco-Hematology Division, Department, Salute della Donna e del Bambino (SDB), University of Padua, 35128 Padua, Italy
| | - Giuseppe Basso
- Onco-Hematology Division, Department, Salute della Donna e del Bambino (SDB), University of Padua, 35128 Padua, Italy
| | - Julie M Gastier-Foster
- Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology, Ohio State University School of Medicine, Columbus, Ohio 43210, USA.,Department of Pediatrics, Ohio State University School of Medicine, Columbus, Ohio 43210, USA.,Children's Oncology Group, Arcadia, California 91006, USA
| | - Mignon L Loh
- Department of Pediatrics, University of California, San Francisco, California 94143, USA.,Helen Diller Family Comprehensive Cancer Center, San Francisco, California 94115, USA
| | - Renate Kirschner-Schwabe
- Department of Pediatric Oncology/Hematology, Charité-Universitätsmedizin Berlin, Berlin, 10117, Germany
| | - Charles G Mullighan
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
| | - Raul Rabadan
- Department of Systems Biology, Columbia University, New York, New York 10032, USA.,Department of Biomedical Informatics, Columbia University, New York, New York 10032, USA
| | - Adolfo A Ferrando
- Institute for Cancer Genetics, Columbia University, New York, New York 10032, USA.,Department of Systems Biology, Columbia University, New York, New York 10032, USA.,Department of Pediatrics, Columbia University Medical Center, New York, New York 10032, USA.,Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York 10032, USA
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6
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A nucleotide-controlled conformational switch modulates the activity of eukaryotic IMP dehydrogenases. Sci Rep 2017; 7:2648. [PMID: 28572600 PMCID: PMC5454003 DOI: 10.1038/s41598-017-02805-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/19/2017] [Indexed: 12/31/2022] Open
Abstract
Inosine-5′-monophosphate dehydrogenase (IMPDH) is an essential enzyme for nucleotide metabolism and cell proliferation. Despite IMPDH is the target of drugs with antiviral, immunosuppressive and antitumor activities, its physiological mechanisms of regulation remain largely unknown. Using the enzyme from the industrial fungus Ashbya gossypii, we demonstrate that the binding of adenine and guanine nucleotides to the canonical nucleotide binding sites of the regulatory Bateman domain induces different enzyme conformations with significantly distinct catalytic activities. Thereby, the comparison of their high-resolution structures defines the mechanistic and structural details of a nucleotide-controlled conformational switch that allosterically modulates the catalytic activity of eukaryotic IMPDHs. Remarkably, retinopathy-associated mutations lie within the mechanical hinges of the conformational change, highlighting its physiological relevance. Our results expand the mechanistic repertoire of Bateman domains and pave the road to new approaches targeting IMPDHs.
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7
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Vašák M, Schnabl J. Sodium and Potassium Ions in Proteins and Enzyme Catalysis. Met Ions Life Sci 2016; 16:259-90. [DOI: 10.1007/978-3-319-21756-7_8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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8
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Buey RM, Ledesma-Amaro R, Balsera M, de Pereda JM, Revuelta JL. Increased riboflavin production by manipulation of inosine 5'-monophosphate dehydrogenase in Ashbya gossypii. Appl Microbiol Biotechnol 2015; 99:9577-89. [PMID: 26150243 DOI: 10.1007/s00253-015-6710-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/15/2015] [Accepted: 05/19/2015] [Indexed: 12/13/2022]
Abstract
Guanine nucleotides are the precursors of essential biomolecules including nucleic acids and vitamins such as riboflavin. The enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) catalyzes the ratelimiting step in the guanine nucleotide de novo biosynthetic pathway and plays a key role in controlling the cellular nucleotide pools. Thus, IMPDH is an important metabolic bottleneck in the guanine nucleotide synthesis, susceptible of manipulation by means of metabolic engineering approaches. Herein, we report the functional and structural characterization of the IMPDH enzyme from the industrial fungus Ashbya gossypii. Our data show that the overexpression of the IMPDH gene increases the metabolic flux through the guanine pathway and ultimately enhances 40 % riboflavin production with respect to the wild type. Also, IMPDH disruption results in a 100-fold increase of inosine excretion to the culture media. Our results contribute to the developing metabolic engineering toolbox aiming at improving the production of metabolites with biotechnological interest in A. gossypii.
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Affiliation(s)
- Rubén M Buey
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
| | | | - Mónica Balsera
- Department Abiotic Stress, Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, C/ Cordel de Merinas 40-52, 37008, Salamanca, Spain
| | - José María de Pereda
- Instituto de Biología Celular y Molecular del Cáncer, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain
| | - José Luis Revuelta
- Metabolic Engineering Group, Departamento de Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
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9
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Bioactive nucleoside analogues possessing selected five-membered azaheterocyclic bases. Eur J Med Chem 2015; 97:409-18. [DOI: 10.1016/j.ejmech.2014.11.057] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 11/23/2022]
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10
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Makowska-Grzyska M, Kim Y, Maltseva N, Osipiuk J, Gu M, Zhang M, Mandapati K, Gollapalli DR, Gorla SK, Hedstrom L, Joachimiak A. A novel cofactor-binding mode in bacterial IMP dehydrogenases explains inhibitor selectivity. J Biol Chem 2015; 290:5893-911. [PMID: 25572472 PMCID: PMC4342496 DOI: 10.1074/jbc.m114.619767] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The steadily rising frequency of emerging diseases and antibiotic resistance creates an urgent need for new drugs and targets. Inosine 5'-monophosphate dehydrogenase (IMP dehydrogenase or IMPDH) is a promising target for the development of new antimicrobial agents. IMPDH catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD(+), which is the pivotal step in the biosynthesis of guanine nucleotides. Potent inhibitors of bacterial IMPDHs have been identified that bind in a structurally distinct pocket that is absent in eukaryotic IMPDHs. The physiological role of this pocket was not understood. Here, we report the structures of complexes with different classes of inhibitors of Bacillus anthracis, Campylobacter jejuni, and Clostridium perfringens IMPDHs. These structures in combination with inhibition studies provide important insights into the interactions that modulate selectivity and potency. We also present two structures of the Vibrio cholerae IMPDH in complex with IMP/NAD(+) and XMP/NAD(+). In both structures, the cofactor assumes a dramatically different conformation than reported previously for eukaryotic IMPDHs and other dehydrogenases, with the major change observed for the position of the NAD(+) adenosine moiety. More importantly, this new NAD(+)-binding site involves the same pocket that is utilized by the inhibitors. Thus, the bacterial IMPDH-specific NAD(+)-binding mode helps to rationalize the conformation adopted by several classes of prokaryotic IMPDH inhibitors. These findings offer a potential strategy for further ligand optimization.
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Affiliation(s)
- Magdalena Makowska-Grzyska
- From the Center for Structural Genomics of Infectious Diseases, Computational Institute, University of Chicago, Chicago, Illinois 60637
| | - Youngchang Kim
- From the Center for Structural Genomics of Infectious Diseases, the Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, and Computational Institute, University of Chicago, Chicago, Illinois 60637
| | - Natalia Maltseva
- From the Center for Structural Genomics of Infectious Diseases, Computational Institute, University of Chicago, Chicago, Illinois 60637
| | - Jerzy Osipiuk
- From the Center for Structural Genomics of Infectious Diseases, the Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, and Computational Institute, University of Chicago, Chicago, Illinois 60637
| | - Minyi Gu
- From the Center for Structural Genomics of Infectious Diseases, Computational Institute, University of Chicago, Chicago, Illinois 60637
| | | | | | | | | | - Lizbeth Hedstrom
- the Departments of Biology and Chemistry, Brandeis University, Waltham, Massachusetts 024549110
| | - Andrzej Joachimiak
- From the Center for Structural Genomics of Infectious Diseases, the Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, and Computational Institute, University of Chicago, Chicago, Illinois 60637,
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11
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Zhang Q, Zhou X, Wu R, Mosley A, Zeng SX, Xing Z, Lu H. The role of IMP dehydrogenase 2 in Inauhzin-induced ribosomal stress. eLife 2014; 3. [PMID: 25347121 PMCID: PMC4209374 DOI: 10.7554/elife.03077] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 10/06/2014] [Indexed: 11/13/2022] Open
Abstract
The 'ribosomal stress (RS)-p53 pathway' is triggered by any stressor or genetic alteration that disrupts ribosomal biogenesis, and mediated by several ribosomal proteins (RPs), such as RPL11 and RPL5, which inhibit MDM2 and activate p53. Inosine monophosphate (IMP) dehydrogenase 2 (IMPDH2) is a rate-limiting enzyme in de novo guanine nucleotide biosynthesis and crucial for maintaining cellular guanine deoxy- and ribonucleotide pools needed for DNA and RNA synthesis. It is highly expressed in many malignancies. We previously showed that inhibition of IMPDH2 leads to p53 activation by causing RS. Surprisingly, our current study reveals that Inauzhin (INZ), a novel non-genotoxic p53 activator by inhibiting SIRT1, can also inhibit cellular IMPDH2 activity, and reduce the levels of cellular GTP and GTP-binding nucleostemin that is essential for rRNA processing. Consequently, INZ induces RS and the RPL11/RPL5-MDM2 interaction, activating p53. These results support the new notion that INZ suppresses cancer cell growth by dually targeting SIRT1 and IMPDH2.
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Affiliation(s)
- Qi Zhang
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, United States
| | - Xiang Zhou
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, United States
| | - RuiZhi Wu
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, United States
| | - Amber Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, United States
| | - Shelya X Zeng
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, United States
| | - Zhen Xing
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, United States
| | - Hua Lu
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, United States
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12
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Analyses of cobalt-ligand and potassium-ligand bond lengths in metalloproteins: trends and patterns. J Mol Model 2014; 20:2271. [PMID: 24850495 DOI: 10.1007/s00894-014-2271-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 04/23/2014] [Indexed: 10/25/2022]
Abstract
Cobalt and potassium are biologically important metal elements that are present in a large array of proteins. Cobalt is mostly found in vivo associated with a corrin ring, which represents the core of the vitamin B12 molecule. Potassium is the most abundant metal in the cytosol, and it plays a crucial role in maintaining membrane potential as well as correct protein function. Here, we report a thorough analysis of the geometric properties of cobalt and potassium coordination spheres that was performed with high resolution on a representative set of structures from the Protein Data Bank and complemented by quantum mechanical calculations realized at the DFT level of theory (B3LYP/ SDD) on mononuclear model systems. The results allowed us to draw interesting conclusions on the structural characteristics of both Co and K centers, and to evaluate the importance of effects such as their association energies and intrinsic thermodynamic stabilities. Overall, the results obtained provide useful data for enhancing the atomic models normally applied in theoretical and computational studies of Co or K proteins performed at the quantum mechanical level, and for developing molecular mechanical parameters for treating Co or K coordination spheres in molecular mechanics or molecular dynamics studies.
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13
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Tanaka E, Inoue E, Kawaguchi Y, Tomatsu T, Yamanaka H, Hara M, Kamatani N. Acceptability and usefulness of mizoribine in the management of rheumatoid arthritis in methotrexate-refractory patients and elderly patients, based on analysis of data from a large-scale observational cohort study. Mod Rheumatol 2014. [DOI: 10.3109/s10165-006-0487-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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14
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Synthesis of a novel carbocyclic analog of bredinin. Molecules 2013; 18:11576-85. [PMID: 24048288 PMCID: PMC6270366 DOI: 10.3390/molecules180911576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 09/05/2013] [Accepted: 09/10/2013] [Indexed: 11/16/2022] Open
Abstract
The natural nucleoside antibiotic, bredinin, exhibits antiviral and other biological activities. While various nucleosides related to bredinin have been synthesized, its carbocyclic analog has remained unknown. Synthesis of this heretofore unknown analog of bredinin is described. The key precursor, (3aS,4R,6R,6aR)-6-((methoxy-methoxy)methyl)-2,2-dimethyltetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-amine (5), was prepared from the commercially available compound, (1R,4S)-2-azabicyclo[2.2.1] hept-5-en-3-one (4). Our initial approach used intermediate 6, derived in three transformations from 5, for the key photolytic step to produce the desired ring-opened precursor to the target compound. This photochemical transformation was unsuccessful. However, an appropriately protected and related precursor was synthesized from 5 through the following side-chain functional group transformations: elaboration of the amino group through malonyl ester formation, oximation at the central carbon, conversion of ester to amide and catalytic reduction of the oxime group. This precursor, on treatment with triethylorthoformate and catalytic acetic acid in ethanol, underwent cyclization to produce the desired 4-carbamoyl-imidazolium-5-olate ring. Deprotection of the latter product proceeded smoothly to give the carbocyclic analog of bredinin. This target molecule exhibits antiviral activity, albeit low, against a number of RNA viruses. Further biological evaluations are in progress.
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Bairagya HR, Mukhopadhyay BP. An insight to the dynamics of conserved water-mediated salt bridge interaction and interdomain recognition in hIMPDH isoforms. J Biomol Struct Dyn 2013; 31:788-808. [DOI: 10.1080/07391102.2012.712458] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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16
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Characterization of the novel Trypanosoma brucei inosine 5'-monophosphate dehydrogenase. Parasitology 2013; 140:735-45. [PMID: 23369253 DOI: 10.1017/s0031182012002090] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There is an alarming rate of human African trypanosomiasis recrudescence in many parts of sub-Saharan Africa. Yet, the disease has no successful chemotherapy. Trypanosoma lacks the enzymatic machinery for the de novo synthesis of purine nucleotides, and is critically dependent on salvage mechanisms. Inosine 5'-monophosphate dehydrogenase (IMPDH) is responsible for the rate-limiting step in guanine nucleotide metabolism. Here, we characterize recombinant Trypanosoma brucei IMPDH (TbIMPDH) to investigate the enzymatic differences between TbIMPDH and host IMPDH. Size-exclusion chromatography and analytical ultracentrifugation sedimentation velocity experiments reveal that TbIMPDH forms a heptamer, different from type 1 and 2 mammalian tetrameric IMPDHs. Kinetic analysis reveals calculated K m values of 30 and 1300 μ m for IMP and NAD, respectively. The obtained K m value of TbIMPDH for NAD is approximately 20-200-fold higher than that of mammalian enzymes and indicative of a different NAD binding mode between trypanosomal and mammalian IMPDHs. Inhibition studies show K i values of 3·2 μ m, 21 nM and 3·3 nM for ribavirin 5'-monophosphate, mycophenolic acid and mizoribine 5'-monophosphate, respectively. Our results show that TbIMPDH is different from its mammalian counterpart and thus may be a good target for further studies on anti-trypanosomal drugs.
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Picard-Jean F, Bougie I, Shuto S, Bisaillon M. The immunosuppressive agent mizoribine monophosphate is an inhibitor of the human RNA capping enzyme. PLoS One 2013; 8:e54621. [PMID: 23349942 PMCID: PMC3547949 DOI: 10.1371/journal.pone.0054621] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 12/13/2012] [Indexed: 11/18/2022] Open
Abstract
Mizoribine monophosphate (MZP) is a specific inhibitor of the cellular inosine-5′-monophosphate dehydrogenase (IMPDH), the enzyme catalyzing the rate-limiting step of de novo guanine nucleotide biosynthesis. MZP is a highly potent antagonistic inhibitor of IMPDH that blocks the proliferation of T and B lymphocytes that use the de novo pathway of guanine nucleotide synthesis almost exclusively. In the present study, we investigated the ability of MZP to directly inhibit the human RNA capping enzyme (HCE), a protein harboring both RNA 5′-triphosphatase and RNA guanylyltransferase activities. HCE is involved in the synthesis of the cap structure found at the 5′ end of eukaryotic mRNAs, which is critical for the splicing of the cap-proximal intron, the transport of mRNAs from the nucleus to the cytoplasm, and for both the stability and translation of mRNAs. Our biochemical studies provide the first insight that MZP can inhibit the formation of the RNA cap structure catalyzed by HCE. In the presence of MZP, the RNA 5′-triphosphatase activity appears to be relatively unaffected while the RNA guanylyltransferase activity is inhibited, indicating that the RNA guanylyltransferase activity is the main target of MZP inhibition. Kinetic studies reveal that MZP is a non-competitive inhibitor that likely targets an allosteric site on HCE. Mizoribine also impairs mRNA capping in living cells, which could account for the global mechanism of action of this therapeutic agent. Together, our study clearly demonstrates that mizoribine monophosphate inhibits the human RNA guanylyltransferase in vitro and impair mRNA capping in cellulo.
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Affiliation(s)
- Frédéric Picard-Jean
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Isabelle Bougie
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Satoshi Shuto
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Martin Bisaillon
- Département de Biochimie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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18
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Yamashita M, Saito T, Ise K, Ishii S, Satoh Y, Saito T, Oshibe I, Shimizu H, Kenjo A, Kimura T, Gotoh M. Mizoribine as sole immunosuppressive agent in islet xenotransplantation models: a candidate immunosuppressant causing no adverse effects on islets. Cell Transplant 2012; 21:535-45. [PMID: 22793062 DOI: 10.3727/096368911x605457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mizoribine (MZ) inhibits the differentiation and proliferation of helper T and B cells after antigen recognition by suppressing the purine biosynthesis pathway and nucleic acid synthesis. MZ has been used in kidney transplantation, but distinct data are unavailable for islet transplantation. The present study investigated the efficacy of MZ for islet xenotransplantation. Immunosuppressive effects of MZ were determined by mixed lymphocyte reaction (MLR) assay in vitro. Toxicities for Wistar rat islets were determined by adenosine triphosphate (ATP) contents of islets during 3-day culture and stimulation index in response to glucose after culture. Immunosuppressive effects in vivo were tested in a Wistar-to-B6 islet xenotransplantation model. MZ was administered continuously for 28 days subcutaneously or intramuscularly. MZ inhibited MLR response by approximately 50% at 0.1 μg/ml. ATP contents decreased with MZ >100 μg/ml, while stimulation index was maintained. Continuous infusion of MZ at 10 mg/kg maintained blood concentrations at 0.13-0.19 μg/ml, while intramuscular injection of MZ at 100 mg/kg/day (peak 520 μg/ml at 1 h postinjection) resulted in below measurable levels (<0.03 μg/ml) within 24 h. Graft survival was significantly prolonged following continuous infusion of 10 mg/kg/day compared to controls (31.0 ± 9.5 vs. 13.2 ± 5.2 days; p = 0.002). Furthermore, animals with intramuscular injection at doses of 3.2, 10, or 100 mg/kg/day showed significantly longer graft survival (20.0 ± 7.5, 22.0 ± 7.31, and 24.5 ± 8.1 days, respectively; p < 0.05 each). Histological examination showed significant suppression of lymphocyte infiltration by MZ administration. MZ showed immunosuppressive effects in an experimental islet xenotransplantation model without adverse effects on endocrine function of islet grafts.
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Affiliation(s)
- Michitoshi Yamashita
- Department of Surgery I, School of Medicine, Fukushima Medical University, Fukushima, Japan
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Morrow CA, Valkov E, Stamp A, Chow EWL, Lee IR, Wronski A, Williams SJ, Hill JM, Djordjevic JT, Kappler U, Kobe B, Fraser JA. De novo GTP biosynthesis is critical for virulence of the fungal pathogen Cryptococcus neoformans. PLoS Pathog 2012; 8:e1002957. [PMID: 23071437 PMCID: PMC3469657 DOI: 10.1371/journal.ppat.1002957] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Accepted: 08/26/2012] [Indexed: 01/01/2023] Open
Abstract
We have investigated the potential of the GTP synthesis pathways as chemotherapeutic targets in the human pathogen Cryptococcus neoformans, a common cause of fatal fungal meningoencephalitis. We find that de novo GTP biosynthesis, but not the alternate salvage pathway, is critical to cryptococcal dissemination and survival in vivo. Loss of inosine monophosphate dehydrogenase (IMPDH) in the de novo pathway results in slow growth and virulence factor defects, while loss of the cognate phosphoribosyltransferase in the salvage pathway yielded no phenotypes. Further, the Cryptococcus species complex displays variable sensitivity to the IMPDH inhibitor mycophenolic acid, and we uncover a rare drug-resistant subtype of C. gattii that suggests an adaptive response to microbial IMPDH inhibitors in its environmental niche. We report the structural and functional characterization of IMPDH from Cryptococcus, revealing insights into the basis for drug resistance and suggesting strategies for the development of fungal-specific inhibitors. The crystal structure reveals the position of the IMPDH moveable flap and catalytic arginine in the open conformation for the first time, plus unique, exploitable differences in the highly conserved active site. Treatment with mycophenolic acid led to significantly increased survival times in a nematode model, validating de novo GTP biosynthesis as an antifungal target in Cryptococcus.
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Affiliation(s)
- Carl A. Morrow
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Eugene Valkov
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Anna Stamp
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Eve W. L. Chow
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - I. Russel Lee
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Ania Wronski
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Simon J. Williams
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Justine M. Hill
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Julianne T. Djordjevic
- Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Sydney, New South Wales, Australia
| | - Ulrike Kappler
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Bostjan Kobe
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - James A. Fraser
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
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20
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Makowska-Grzyska M, Kim Y, Wu R, Wilton R, Gollapalli DR, Wang XK, Zhang R, Jedrzejczak R, Mack JC, Maltseva N, Mulligan R, Binkowski TA, Gornicki P, Kuhn ML, Anderson WF, Hedstrom L, Joachimiak A. Bacillus anthracis inosine 5'-monophosphate dehydrogenase in action: the first bacterial series of structures of phosphate ion-, substrate-, and product-bound complexes. Biochemistry 2012; 51:6148-63. [PMID: 22788966 DOI: 10.1021/bi300511w] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the first unique step of the GMP branch of the purine nucleotide biosynthetic pathway. This enzyme is found in organisms of all three kingdoms. IMPDH inhibitors have broad clinical applications in cancer treatment, as antiviral drugs and as immunosuppressants, and have also displayed antibiotic activity. We have determined three crystal structures of Bacillus anthracis IMPDH, in a phosphate ion-bound (termed "apo") form and in complex with its substrate, inosine 5'-monophosphate (IMP), and product, xanthosine 5'-monophosphate (XMP). This is the first example of a bacterial IMPDH in more than one state from the same organism. Furthermore, for the first time for a prokaryotic enzyme, the entire active site flap, containing the conserved Arg-Tyr dyad, is clearly visible in the structure of the apoenzyme. Kinetic parameters for the enzymatic reaction were also determined, and the inhibitory effect of XMP and mycophenolic acid (MPA) has been studied. In addition, the inhibitory potential of two known Cryptosporidium parvum IMPDH inhibitors was examined for the B. anthracis enzyme and compared with those of three bacterial IMPDHs from Campylobacter jejuni, Clostridium perfringens, and Vibrio cholerae. The structures contribute to the characterization of the active site and design of inhibitors that specifically target B. anthracis and other microbial IMPDH enzymes.
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Affiliation(s)
- Magdalena Makowska-Grzyska
- Center for Structural Genomics of Infectious Diseases, University of Chicago, 5735 South Ellis Avenue, Chicago, IL 60637, USA
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21
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Feverati G, Achoch M, Zrimi J, Vuillon L, Lesieur C. Beta-strand interfaces of non-dimeric protein oligomers are characterized by scattered charged residue patterns. PLoS One 2012; 7:e32558. [PMID: 22496732 PMCID: PMC3322119 DOI: 10.1371/journal.pone.0032558] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 01/29/2012] [Indexed: 11/19/2022] Open
Abstract
Protein oligomers are formed either permanently, transiently or even by default. The protein chains are associated through intermolecular interactions constituting the protein interface. The protein interfaces of 40 soluble protein oligomers of stœchiometries above two are investigated using a quantitative and qualitative methodology, which analyzes the x-ray structures of the protein oligomers and considers their interfaces as interaction networks. The protein oligomers of the dataset share the same geometry of interface, made by the association of two individual β-strands (β-interfaces), but are otherwise unrelated. The results show that the β-interfaces are made of two interdigitated interaction networks. One of them involves interactions between main chain atoms (backbone network) while the other involves interactions between side chain and backbone atoms or between only side chain atoms (side chain network). Each one has its own characteristics which can be associated to a distinct role. The secondary structure of the β-interfaces is implemented through the backbone networks which are enriched with the hydrophobic amino acids favored in intramolecular β-sheets (MCWIV). The intermolecular specificity is provided by the side chain networks via positioning different types of charged residues at the extremities (arginine) and in the middle (glutamic acid and histidine) of the interface. Such charge distribution helps discriminating between sequences of intermolecular β-strands, of intramolecular β-strands and of β-strands forming β-amyloid fibers. This might open new venues for drug designs and predictive tool developments. Moreover, the β-strands of the cholera toxin B subunit interface, when produced individually as synthetic peptides, are capable of inhibiting the assembly of the toxin into pentamers. Thus, their sequences contain the features necessary for a β-interface formation. Such β-strands could be considered as ‘assemblons’, independent associating units, by homology to the foldons (independent folding unit). Such property would be extremely valuable in term of assembly inhibitory drug development.
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Affiliation(s)
| | - Mounia Achoch
- Université de Savoie, Annecy le Vieux Cedex, France
- Laboratoire de Chimie Bioorganique et Macromoléculaire (LCBM), Faculté des Sciences et Techniques-Guéliz, Université Cadi Ayyad, Marrakech, Maroc
| | - Jihad Zrimi
- Université de Savoie, Annecy le Vieux Cedex, France
- Laboratoire de Chimie Bioorganique et Macromoléculaire (LCBM), Faculté des Sciences et Techniques-Guéliz, Université Cadi Ayyad, Marrakech, Maroc
| | | | - Claire Lesieur
- Université de Savoie, Annecy le Vieux Cedex, France
- AGIM, Université Joseph Fourier, Archamps, France
- * E-mail:
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22
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Fukami N, Subramanian V, Angaswamy N, Liu W, Mohanakumar T, Hoshinaga K. Mizoribine—An inosine monophosphate dehydrogenase inhibitor—acts synergistically with cyclosporine A in prolonging survival of murine islet cell and heart transplants across major histocompatibility barrier. Transpl Immunol 2012; 26:140-5. [DOI: 10.1016/j.trim.2011.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 10/26/2011] [Accepted: 10/28/2011] [Indexed: 11/30/2022]
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Hedstrom L. The dynamic determinants of reaction specificity in the IMPDH/GMPR family of (β/α)(8) barrel enzymes. Crit Rev Biochem Mol Biol 2012; 47:250-63. [PMID: 22332716 DOI: 10.3109/10409238.2012.656843] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The inosine monophosphate dehydrogenase (IMPDH)/guanosine monophosphate reductase (GMPR) family of (β/α)(8) enzymes presents an excellent opportunity to investigate how subtle changes in enzyme structure change reaction specificity. IMPDH and GMPR bind the same ligands with similar affinities and share a common set of catalytic residues. Both enzymes catalyze a hydride transfer reaction involving a nicotinamide cofactor hydride, and both reactions proceed via the same covalent intermediate. In the case of IMPDH, this intermediate reacts with water, while in GMPR it reacts with ammonia. In both cases, the two chemical transformations are separated by a conformational change. In IMPDH, the conformational change involves a mobile protein flap while in GMPR, the cofactor moves. Thus reaction specificity is controlled by differences in dynamics, which in turn are controlled by residues outside the active site. These findings have some intriguing implications for the evolution of the IMPDH/GMPR family.
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Affiliation(s)
- Lizbeth Hedstrom
- Departments of Biology and Chemistry, Brandeis University, Waltham, MA 02454, USA.
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24
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Sun XE, Hansen BG, Hedstrom L. Kinetically controlled drug resistance: how Penicillium brevicompactum survives mycophenolic acid. J Biol Chem 2011; 286:40595-600. [PMID: 21979957 PMCID: PMC3220510 DOI: 10.1074/jbc.m111.305235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 10/04/2011] [Indexed: 11/06/2022] Open
Abstract
The filamentous fungus Penicillium brevicompactum produces the immunosuppressive drug mycophenolic acid (MPA), which is a potent inhibitor of eukaryotic IMP dehydrogenases (IMPDHs). IMPDH catalyzes the conversion of IMP to XMP via a covalent enzyme intermediate, E-XMP*; MPA inhibits by trapping E-XMP*. P. brevicompactum (Pb) contains two MPA-resistant IMPDHs, PbIMPDH-A and PbIMPDH-B, which are 17- and 10(3)-fold more resistant to MPA than typically observed. Surprisingly, the active sites of these resistant enzymes are essentially identical to those of MPA-sensitive enzymes, so the mechanistic basis of resistance is not apparent. Here, we show that, unlike MPA-sensitive IMPDHs, formation of E-XMP* is rate-limiting for both PbIMPDH-A and PbIMPDH-B. Therefore, MPA resistance derives from the failure to accumulate the drug-sensitive intermediate.
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Affiliation(s)
- Xin E. Sun
- From the Graduate Program in Biochemistry and
| | - Bjarne Gram Hansen
- the Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Lizbeth Hedstrom
- Departments of Biology and Chemistry, Brandeis University, Waltham, Massachusetts 02453 and
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25
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Patton GC, Stenmark P, Gollapalli DR, Sevastik R, Kursula P, Flodin S, Schuler H, Swales CT, Eklund H, Himo F, Nordlund P, Hedstrom L. Cofactor mobility determines reaction outcome in the IMPDH and GMPR (β-α)8 barrel enzymes. Nat Chem Biol 2011; 7:950-8. [PMID: 22037469 PMCID: PMC4552316 DOI: 10.1038/nchembio.693] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 08/22/2011] [Indexed: 12/13/2022]
Abstract
Inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate reductase (GMPR) belong to the same structural family, share a common set of catalytic residues and bind the same ligands. The structural and mechanistic features that determine reaction outcome in the IMPDH and GMPR family have not been identified. Here we show that the GMPR reaction uses the same intermediate E-XMP* as IMPDH, but in this reaction the intermediate reacts with ammonia instead of water. A single crystal structure of human GMPR type 2 with IMP and NADPH fortuitously captures three different states, each of which mimics a distinct step in the catalytic cycle of GMPR. The cofactor is found in two conformations: an 'in' conformation poised for hydride transfer and an 'out' conformation in which the cofactor is 6 Å from IMP. Mutagenesis along with substrate and cofactor analog experiments demonstrate that the out conformation is required for the deamination of GMP. Remarkably, the cofactor is part of the catalytic machinery that activates ammonia.
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Affiliation(s)
- Gregory C. Patton
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Pål Stenmark
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden
| | | | - Robin Sevastik
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Petri Kursula
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Susanne Flodin
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Herwig Schuler
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Colin T. Swales
- Department of Chemistry, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Hans Eklund
- Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, P.O. Box 590, SE-751 24 Uppsala, Sweden
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pär Nordlund
- Structural Genomics Consortium, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
- School of Biological Sciences, Nanyang Technological University, 61 Nanyang Drive Singapore 639798
| | - Lizbeth Hedstrom
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
- Department of Chemistry, Brandeis University, 415 South Street, Waltham, MA 02453, USA
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26
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Riera TV, Zheng L, Josephine HR, Min D, Yang W, Hedstrom L. Allosteric activation via kinetic control: potassium accelerates a conformational change in IMP dehydrogenase. Biochemistry 2011; 50:8508-18. [PMID: 21870820 PMCID: PMC3186055 DOI: 10.1021/bi200785s] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Allosteric activators are generally believed to shift the equilibrium distribution of enzyme conformations to favor a catalytically productive structure; the kinetics of conformational exchange is seldom addressed. Several observations suggested that the usual allosteric mechanism might not apply to the activation of IMP dehydrogenase (IMPDH) by monovalent cations. Therefore, we investigated the mechanism of K(+) activation in IMPDH by delineating the kinetic mechanism in the absence of monovalent cations. Surprisingly, the K(+) dependence of k(cat) derives from the rate of flap closure, which increases by ≥65-fold in the presence of K(+). We performed both alchemical free energy simulations and potential of mean force calculations using the orthogonal space random walk strategy to computationally analyze how K(+) accelerates this conformational change. The simulations recapitulate the preference of IMPDH for K(+), validating the computational models. When K(+) is replaced with a dummy ion, the residues of the K(+) binding site relax into ordered secondary structure, creating a barrier to conformational exchange. K(+) mobilizes these residues by providing alternate interactions for the main chain carbonyls. Potential of mean force calculations indicate that K(+) changes the shape of the energy well, shrinking the reaction coordinate by shifting the closed conformation toward the open state. This work suggests that allosteric regulation can be under kinetic as well as thermodynamic control.
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Affiliation(s)
- Thomas V. Riera
- Graduate Program in Biochemistry, Brandeis University, 415 South St., MS 009, Waltham, MA 02454 USA
| | - Lianqing Zheng
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306 USA
| | - Helen R. Josephine
- Department of Biology, Brandeis University, 415 South St., MS 009, Waltham, MA 02454 USA
| | - Donghong Min
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306 USA
| | - Wei Yang
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306 USA
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 USA
| | - Lizbeth Hedstrom
- Department of Biology, Brandeis University, 415 South St., MS 009, Waltham, MA 02454 USA
- Department of Chemistry, Brandeis University, 415 South St., MS 009, Waltham, MA 02454 USA
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27
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Takahashi K, Oharaseki T, Nagao T, Yokouchi Y, Yamada H, Nagi-Miura N, Ohno N, Saji T, Okazaki T, Suzuki K. Mizoribine provides effective treatment of sequential histological change of arteritis and reduction of inflammatory cytokines and chemokines in an animal model of Kawasaki disease. Pediatr Rheumatol Online J 2011; 9:30. [PMID: 21958311 PMCID: PMC3239324 DOI: 10.1186/1546-0096-9-30] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 09/29/2011] [Indexed: 11/10/2022] Open
Abstract
UNLABELLED The incidence of panvasculitis in the coronary arteries and aortic root was 100% in the control group. The incidence of panvasculitis in the MZR group decreased to 50%. Moreover, the scope and severity of the inflammation of those sites were significantly reduced in the MZR group as well as the IgG group. On the other hand, increased cytokines and chemokines, such as IL-1α, TNF-α, KC, MIP-1α, GM-CSF, and IL-13, in the nontreatment group were significantly suppressed by treatment with MZR, but the MCP-1 level increased. In addition, IL-1α, TNF-α, IL-10, IL-13, and MIP-1α were suppressed by treatment in the IgG group. BACKGROUND Intravenous immunoglobulin (IVIg) treatment results in an effective response from patients with acute-phase Kawasaki disease (KD), but 16.5% of them remain nonresponsive to IVIg. To address this therapeutic challenge, we tried a new therapeutic drug, mizoribine (MZR), in a mouse model of KD, which we have established using injections of Candida albicans water-soluble fractions (CAWS). METHODS CAWS (4 mg/mouse) were injected intraperitoneally into C57BL/6N mice for 5 consecutive days. MZR or IgG was administered for 5 days. After 4 weeks, the mice were sacrificed and autopsied, the hearts were fixed in 10% neutral formalin, and plasma was taken to measure cytokines and chemokines using the Bio-Plex system. RESULTS The incidence of panvasculitis in the coronary arteries and aortic root was 100% in the control group. The incidence of panvasculitis in the MZR group decreased to 50%. Moreover, the scope and severity of the inflammation of those sites were significantly reduced in the MZR group as well as the IgG group. On the other hand, increased cytokines and chemokines, such as IL-1α TNF-α, KC, MIP-1α, GM-CSF, and IL-13, in the nontreatment group were significantly suppressed by treatment with MZR, but the MCP-1 level increased. In addition, IL-1α, TNF-α, IL-10, IL-13, and MIP-1α were suppressed by treatment in the IgG group. CONCLUSION MZR treatment suppressed not only the incidence, range, and degree of vasculitis, but also inflammatory cytokines and chemokines in the plasma of the KD vasculitis model mice, suggesting that MZR may be useful for treatment of KD.
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Affiliation(s)
- Kei Takahashi
- Inflammation Program, Dept, of Immunology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba, 260-8670, Japan.
| | - Toshiaki Oharaseki
- Department of Pathology, Toho University Ohashi Medical Center, Meguro-ku, Tokyo, 153-8515, Japan
| | - Tomokazu Nagao
- Inflammation Program, Dept. of Immunology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba, 260-8670, Japan
| | - Yuki Yokouchi
- Department of Pathology, Toho University Ohashi Medical Center, Meguro-ku, Tokyo, 153-8515, Japan
| | - Hitomi Yamada
- Department of Pathology, Toho University Ohashi Medical Center, Meguro-ku, Tokyo, 153-8515, Japan
| | - Noriko Nagi-Miura
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo 192-0392, Japan
| | - Naohito Ohno
- Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo 192-0392, Japan
| | - Tsutomu Saji
- Department of Pediatrics, Toho University Omori Medical Center, Ota-ku, Tokyo, 143-8541, Japan
| | - Tomio Okazaki
- Kure Kyosai Hospital, Kure, Hiroshima, 737-8505, Japan
| | - Kazuo Suzuki
- Inflammation Program, Dept. of Immunology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba, 260-8670, Japan
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Inosine monophosphate dehydrogenase as a target for antiviral, anticancer, antimicrobial and immunosuppressive therapeutics. Future Med Chem 2011; 2:81-92. [PMID: 21426047 DOI: 10.4155/fmc.09.147] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in the de novo biosynthesis of guanine nucleotides. In recent years it has become the target of multiple drugs in an attempt to cure a variety of diseases. Possible therapeutic drugs range from antiviral and anticancer to immunosuppressive targets. Research has shown that if IMPDH is effectively inhibited, cancerous growth can be slowed and virus replication can be stopped. Microbial and parasitic IMPDH differ significantly from the human isoforms and targeting those isoforms could lead to effective treatments for many diseases. Inhibiting IMPDH is an extremely promising therapy for a variety of disease states. Isoform- and species-selective inhibition is desirable and scientists are making significant progress in these areas.
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Ostrowski T, Januszczyk P, Cieslak M, Kazmierczak-Baranska J, Nawrot B, Bartoszak-Adamska E, Zeidler J. 5-Ethynyl-1-β-D-ribofuranosyl-1H-[1,2,3]triazole-4-carboxylic acid amide (ETCAR) and its analogues: synthesis and cytotoxic properties. Bioorg Med Chem 2011; 19:4386-98. [PMID: 21684167 DOI: 10.1016/j.bmc.2011.05.050] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 05/05/2011] [Accepted: 05/09/2011] [Indexed: 11/16/2022]
Abstract
Efficient Pd(0)-catalysed synthesis of 5-alkynyl-1-β-D-ribofuranosyl-1H-[1,2,3]triazole-4-carboxylic acid amide depends on the presence of different protecting groups of the ribose moiety. Peracetylated 5-iodo substrate (15) couples with terminal alkynes or trimethyl-[(tributylstannyl)ethynyl]silane in 50-71% and 72% yield (ETCAR), respectively, although its hydrodehalogenation to 19 is noticeable. On the other hand, hydrodehalogenation of acetonide (16) predominates over coupling with terminal alkyne and slightly decreases a yield of cross-coupling reaction with trimethyl[(tributylstannyl)ethynyl]silane. Alternative conditions of reaction with terminal alkynes, to exclude so far identified hydride sources to produce hydridopalladium species, have been established for acetonide 16 and allowed to achieve 72% of coupling. Fluoromethyl derivative (42) was prepared from its 5-hydroxymethyl precursor by fluorination with DAST. Additionally, X-ray structural analysis of 42 was performed. All 1,2,3-triazolonucleosides and two synthesized cycloSal-pronucleotides were evaluated for cytotoxic activity against K562, HeLa and HUVEC cells.
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Affiliation(s)
- Tomasz Ostrowski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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Gollapalli DR, Macpherson IS, Liechti G, Gorla SK, Goldberg JB, Hedstrom L. Structural determinants of inhibitor selectivity in prokaryotic IMP dehydrogenases. ACTA ACUST UNITED AC 2011; 17:1084-91. [PMID: 21035731 DOI: 10.1016/j.chembiol.2010.07.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 06/26/2010] [Accepted: 07/20/2010] [Indexed: 10/18/2022]
Abstract
The protozoan parasite Cryptosporidium parvum is a major cause of gastrointestinal disease; no effective drug therapy exists to treat this infection. Curiously, C. parvum IMPDH (CpIMPDH) is most closely related to prokaryotic IMPDHs, suggesting that the parasite obtained its IMPDH gene via horizontal transfer. We previously identified inhibitors of CpIMPDH that do not inhibit human IMPDHs. Here, we show that these compounds also inhibit IMPDHs from Helicobacter pylori, Borrelia burgdorferi, and Streptococcus pyogenes, but not from Escherichia coli. Residues Ala165 and Tyr358 comprise a structural motif that defines susceptible enzymes. Importantly, a second-generation CpIMPDH inhibitor has bacteriocidal activity on H. pylori but not E. coli. We propose that CpIMPDH-targeted inhibitors can be developed into a new class of antibiotics that will spare some commensal bacteria.
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31
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Josephine HR, Ravichandran KR, Hedstrom L. The Cys319 loop modulates the transition between dehydrogenase and hydrolase conformations in inosine 5'-monophosphate dehydrogenase. Biochemistry 2010; 49:10674-81. [PMID: 21062060 DOI: 10.1021/bi101590c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
X-ray crystal structures of enzyme-ligand complexes are widely believed to mimic states in the catalytic cycle, but this presumption has seldom been carefully scrutinized. In the case of Tritrichomonas foetus inosine 5'-monophosphate dehydrogenase (IMPDH), 10 structures of various enzyme-substrate-inhibitor complexes have been determined. The Cys319 loop is found in at least three different conformations, suggesting that its conformation changes as the catalytic cycle progresses from the dehydrogenase step to the hydrolase reaction. Alternatively, only one conformation of the Cys319 loop may be catalytically relevant while the others are off-pathway. Here we differentiate between these two hypotheses by analyzing the effects of Ala substitutions at three residues of the Cys319 loop, Arg322, Glu323, and Gln324. These mutations have minimal effects on the value of k(cat) (≤5-fold) that obscure large effects (>10-fold) on the microscopic rate constants for individual steps. These substitutions increase the equilibrium constant for the dehydrogenase step but decrease the equilibrium between open and closed conformations of a mobile flap. More dramatic effects are observed when Arg322 is substituted with Glu, which decreases the rates of hydride transfer and hydrolysis by factors of 2000 and 130, respectively. These experiments suggest that the Cys319 loop does indeed have different conformations during the dehydrogenase and hydrolase reactions as suggested by the crystal structures. Importantly, these experiments reveal that the structure of the Cys319 loop modulates the closure of the mobile flap. This conformational change converts the enzyme from a dehydrogenase into hydrolase, suggesting that the conformation of the Cys319 loop may gate the catalytic cycle.
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Affiliation(s)
- Helen R Josephine
- Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110, United States
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32
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Bushnell EAC, Erdtman E, Llano J, Eriksson LA, Gauld JW. The first branching point in porphyrin biosynthesis: A systematic docking, molecular dynamics and quantum mechanical/molecular mechanical study of substrate binding and mechanism of uroporphyrinogen-III decarboxylase. J Comput Chem 2010; 32:822-34. [DOI: 10.1002/jcc.21661] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 08/07/2010] [Indexed: 11/06/2022]
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Bairagya HR, Mukhopadhyay BP, Bera AK. Conserved water mediated recognition and the dynamics of active site Cys 331 and Tyr 411 in hydrated structure of human IMPDH-II. J Mol Recognit 2010; 24:35-44. [DOI: 10.1002/jmr.1021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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34
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Affiliation(s)
- Lizbeth Hedstrom
- Department of Biology, Brandeis University, MS009, 415 South Street, Waltham, Massachusetts 02454, USA.
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35
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Abstract
Understanding the molecular mechanisms underlying synergistic, potentiative and antagonistic effects of drug combinations could facilitate the discovery of novel efficacious combinations and multi-targeted agents. In this article, we describe an extensive investigation of the published literature on drug combinations for which the combination effect has been evaluated by rigorous analysis methods and for which relevant molecular interaction profiles of the drugs involved are available. Analysis of the 117 drug combinations identified reveals general and specific modes of action, and highlights the potential value of molecular interaction profiles in the discovery of novel multicomponent therapies.
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Ota H, Yasuda Y, Sakasegawa SI, Imamura S, Tamura T. A Novel Enzymatic Method for Measuring Mizoribine 5′-Monophosphate Levels in Serum. J Biosci Bioeng 2008; 106:511-4. [DOI: 10.1263/jbb.106.511] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 07/17/2008] [Indexed: 11/17/2022]
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An enzymatic atavist revealed in dual pathways for water activation. PLoS Biol 2008; 6:e206. [PMID: 18752347 PMCID: PMC2525682 DOI: 10.1371/journal.pbio.0060206] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Accepted: 07/15/2008] [Indexed: 11/21/2022] Open
Abstract
Inosine monophosphate dehydrogenase (IMPDH) catalyzes an essential step in the biosynthesis of guanine nucleotides. This reaction involves two different chemical transformations, an NAD-linked redox reaction and a hydrolase reaction, that utilize mutually exclusive protein conformations with distinct catalytic residues. How did Nature construct such a complicated catalyst? Here we employ a “Wang-Landau” metadynamics algorithm in hybrid quantum mechanical/molecular mechanical (QM/MM) simulations to investigate the mechanism of the hydrolase reaction. These simulations show that the lowest energy pathway utilizes Arg418 as the base that activates water, in remarkable agreement with previous experiments. Surprisingly, the simulations also reveal a second pathway for water activation involving a proton relay from Thr321 to Glu431. The energy barrier for the Thr321 pathway is similar to the barrier observed experimentally when Arg418 is removed by mutation. The Thr321 pathway dominates at low pH when Arg418 is protonated, which predicts that the substitution of Glu431 with Gln will shift the pH-rate profile to the right. This prediction is confirmed in subsequent experiments. Phylogenetic analysis suggests that the Thr321 pathway was present in the ancestral enzyme, but was lost when the eukaryotic lineage diverged. We propose that the primordial IMPDH utilized the Thr321 pathway exclusively, and that this mechanism became obsolete when the more sophisticated catalytic machinery of the Arg418 pathway was installed. Thus, our simulations provide an unanticipated window into the evolution of a complex enzyme. Many enzymes have the remarkable ability to catalyze several different chemical transformations. For example, IMP dehydrogenase catalyzes both an NAD-linked redox reaction and a hydrolase reaction. These reactions utilize distinct catalytic residues and protein conformations. How did Nature construct such a complicated catalyst? While using computational methods to investigate the mechanism of the hydrolase reaction, we have discovered that IMP dehydrogenase contains two sets of catalytic residues to activate water. Importantly, the simulations are in good agreement with previous experimental observations and are further validated by subsequent experiments. Phylogenetic analysis suggests that the simpler, less efficient catalytic machinery was present in the ancestral enzyme, but was lost when the eukaryotic lineage diverged. We propose that the primordial IMP dehydrogenase utilized the less efficient machinery exclusively, and that this mechanism became obsolete when the more sophisticated catalytic machinery evolved. The presence of the less efficient machinery could facilitate adaptation, making the evolutionary challenge of the IMPDH reaction much less formidable. Thus our simulations provide an unanticipated window into the evolution of a complex enzyme. How does nature construct complex catalysts? Molecular simulations revealed two sets of catalytic residues in the enzyme IMPDH, one of which seems to represent a primitive catalytic machinery that may be a vestige of evolution.
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Pouwels LJ, Zhang L, Chan NH, Dorrestein PC, Wachter RM. Kinetic isotope effect studies on the de novo rate of chromophore formation in fast- and slow-maturing GFP variants. Biochemistry 2008; 47:10111-22. [PMID: 18759496 DOI: 10.1021/bi8007164] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The maturation process of green fluorescent protein (GFP) entails a protein oxidation reaction triggered by spontaneous backbone condensation. The chromophore is generated by full conjugation of the Tyr66 phenolic group with the heterocycle, a process that requires C-H bond scission at the benzylic carbon. We have prepared isotope-enriched protein bearing tyrosine residues deuterated at the beta carbon, and have determined kinetic isotope effects (KIEs) on the GFP self-processing reaction. Progress curves for the production of H 2O 2 and the mature chromophore were analyzed by global curve fitting to a three-step mechanism describing preoxidation, oxidation and postoxidation events. Although a KIE for protein oxidation could not be discerned ( k H/ k D = 1.1 +/- 0.2), a full primary KIE of 5.9 (+/-2.8) was extracted for the postoxidation step. Therefore, the exocyclic carbon is not involved in the reduction of molecular oxygen. Rather, C-H bond cleavage proceeds from the oxidized cyclic imine form, and is the rate-limiting event of the final step. Substantial pH-dependence of maturation was observed upon substitution of the catalytic glutamate (E222Q), indicating an apparent p K a of 9.4 (+/-0.1) for the base catalyst. For this variant, a KIE of 5.8 (+/-0.4) was determined for the intrinsic time constant that is thought to describe the final step, as supported by ultra-high resolution mass spectrometric results. The data are consistent with general base catalysis of the postoxidation events yielding green color. Structural arguments suggest a mechanism in which the highly conserved Arg96 serves as catalytic base in proton abstraction from the Tyr66-derived beta carbon.
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Affiliation(s)
- Lauren J Pouwels
- The Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA
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39
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Riera TV, Wang W, Josephine HR, Hedstrom L. A kinetic alignment of orthologous inosine-5'-monophosphate dehydrogenases. Biochemistry 2008; 47:8689-96. [PMID: 18642884 PMCID: PMC2646883 DOI: 10.1021/bi800674a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
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IMP dehydrogenase (IMPDH) catalyzes two very different chemical transformations, a dehydrogenase reaction and a hydrolysis reaction. The enzyme toggles between the open conformation required for the dehydrogenase reaction and the closed conformation of the hydrolase reaction by moving a mobile flap into the NAD site. Despite these multiple functional constraints, the residues of the flap and NAD site are highly diverged, and the equilibrium between open and closed conformations (Kc) varies widely. In order to understand how differences in the dynamic properties of the flap influence the catalytic cycle, we have delineated the kinetic mechanism of IMPDH from the pathogenic protozoan parasite Cryptosporidium parvum (CpIMPDH), which was obtained from a bacterial source through horizontal gene transfer, and its host counterpart, human IMPDH type 2 (hIMPDH2). Interestingly, the intrinsic binding energy of NAD+ differentially distributes across the dinucleotide binding sites of these two enzymes as well as in the previously characterized IMPDH from Tritrichomonas foetus (TfIMPDH). Both the dehydrogenase and hydrolase reactions display significant differences in the host and parasite enzymes, in keeping with the phylogenetic and structural divergence of their active sites. Despite large differences in Kc, the catalytic power of both the dehydrogenase and hydrolase conformations are similar in CpIMPDH and TfIMPDH. This observation suggests that the closure of the flap simply sets the stage for catalysis rather than plays a more active role in the chemical transformation. This work provides the essential mechanistic framework for drug discovery.
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Affiliation(s)
- Thomas V Riera
- Departments of Biochemistry and Chemistry, Brandeis University, Waltham, Massachusetts 02454, USA
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Leyssen P, De Clercq E, Neyts J. Molecular strategies to inhibit the replication of RNA viruses. Antiviral Res 2008; 78:9-25. [PMID: 18313769 PMCID: PMC7114363 DOI: 10.1016/j.antiviral.2008.01.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/04/2008] [Accepted: 01/08/2008] [Indexed: 12/24/2022]
Abstract
There are virtually no antiviral drugs available for the treatment of infections with RNA viruses. This is particularly worrisome since most of the highly pathogenic and emerging viruses are, and will likely continue to be, RNA viruses. These viruses can cause acute, severe illness, including severe respiratory disease, hemorrhagic fever and encephalitis, with a high case fatality rate. It is important to have potent and safe drugs at hand that can be used for the treatment or prophylaxis of such infections. Drugs approved for the treatment of RNA virus infections (other than HIV) are the influenza M2 channel inhibitors, amantadine and rimantadine; the influenza neuraminidase inhibitors, oseltamivir and zanamivir, and ribavirin for the treatment of infections with respiratory syncytial virus and hepatitis C virus. The molecular mechanism(s) by which ribavirin inhibits viral replication, such as depletion of intracellular GTP pools and induction of error catastrophe, may not readily allow the design of analogues that are more potent/selective than the parent drug. Highly pathogenic RNA viruses belong to a variety of virus families, each having a particular replication strategy, thus offering a wealth of potential targets to selectively inhibit viral replication. We here provide a non-exhaustive review of potential experimental strategies, using small molecules, to inhibit the replication of several RNA viruses. Other approaches, such as the use of interferon or other host-response modifiers, immune serum or neutralizing antibodies, are not addressed in this review.
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Affiliation(s)
| | | | - Johan Neyts
- Rega Institute for Medical Research, Catholic University Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
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41
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Affiliation(s)
- James P McEvoy
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA
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42
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Dobie F, Berg A, Boitz JM, Jardim A. Kinetic characterization of inosine monophosphate dehydrogenase of Leishmania donovani. Mol Biochem Parasitol 2006; 152:11-21. [PMID: 17173987 DOI: 10.1016/j.molbiopara.2006.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2006] [Revised: 11/08/2006] [Accepted: 11/14/2006] [Indexed: 11/27/2022]
Abstract
Trypanosomatid protozoan pathogens are purine auxotrophs that are highly dependent on the enzyme inosine monophosphate dehydrogenase (IMPDH) for the synthesis of guanylate nucleotides. Enzymatic characterization of the Leishmania donovani IMPDH (LdIMPDH) overexpressed in E. coli revealed that this enzyme was highly specific for the substrates IMP and NAD(+) with K(m)(app) values of 33 and 390 microM, respectively. In contrast to other IMPDHs, LdIMPDH exhibits no substrate inhibition in high concentrations of NAD(+). Kinetic studies revealed that XMP and GMP were inhibitors with K(i) values of approximately 26 and 210 microM, respectively, suggesting that these nucleotides may regulate LdIMPDH activity. Mycophenolic acid was also a potent inhibitor of L. donovani IMPDH with a K(i) value of approximately 25 nM. Confocal immunofluorescence microscopy and subcellular fractionation localized LdIMPDH to the glycosome. Protein-protein interaction assays revealed that LdIMPDH associated tightly with glycosomal protein sorting receptor LdPEX5.
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Affiliation(s)
- Fredrick Dobie
- Institute of Parasitology, Macdonald Campus of McGill University, 21, 111 Lakeshore Road, Ste. Anne-de-Bellevue, Quebec, Canada H9X 3V9
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Tanaka E, Inoue E, Kawaguchi Y, Tomatsu T, Yamanaka H, Hara M, Kamatani N. Acceptability and usefulness of mizoribine in the management of rheumatoid arthritis in methotrexate-refractory patients and elderly patients, based on analysis of data from a large-scale observational cohort study. Mod Rheumatol 2006; 16:214-9. [PMID: 16906370 DOI: 10.1007/s10165-006-0487-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 04/27/2006] [Indexed: 10/24/2022]
Abstract
This report documents the results of a study performed to examine clinical use of mizoribine (MZR), using data from a large-scale prospective cohort study, IORRA (Institute of Rheumatology Rheumatoid Arthritis). The number of patients with RA entered in this study from October 2000 through October 2003 was 6238. Three hundred and six patients (4.9%) received MZR therapy. Mizoribine users who were taking methotrexate (MTX) (MTX-MZR group, n = 94) and over 70 years of age (elderly group, n = 45) were collected. Cumulative retention rates of MZR were calculated by Kaplan-Meier analysis. Median drug survival of MZR was 28 months for the poor responders to MTX and 43 months for the poor responders to MZR, with no significant difference between these groups. Cumulative retention rate of MZR in the elderly group did not show a significant difference compared to that in patients aged under 70 years. Ten patients (10.6%) in the MTX-MZR group and 10 patients (22.2%) in the elderly group experienced adverse effects of MZR. None of these adverse effects was serious. This study indicated that, although MZR has not been frequently prescribed for RA patients, it may be useful and relatively safe for patients who are poor responders to MTX as an additional regimen to MTX therapy as well as for elderly patients.
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Affiliation(s)
- Eiichi Tanaka
- Institute of Rheumatology, Tokyo Women's Medical University, 10-22 Kawada-cho, Shinjuku-ku, Tokyo, 162-0054, Japan
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Shimmura H, Tanabe K, Habiro K, Abe R, Toma H. Combination effect of mycophenolate mofetil with mizoribine on cell proliferation assays and in a mouse heart transplantation model. Transplantation 2006; 82:175-9. [PMID: 16858279 DOI: 10.1097/01.tp.0000226227.79142.31] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Mycophenolate mofetil (MMF) is a highly potent immunosuppressant that suppresses the proliferation of T and B cells by the uncompetitive inhibition of inosine monophosphate dehydrogenase (IMPDH). Consequently, under MMF immunosuppression, good graft survival has been achieved in clinical organ transplantation, although MMF shows adverse gastrointestinal effects. Mizoribine (MZ) also inhibits IMPDH in a competitive manner and is used clinically for organ transplantation in Japan as an immunosuppressant with fewer adverse gastrointestinal effects. Therefore, in this study we investigated the synergistic effects on in vitro and in vivo assays of mice of a combination of MMF with MZ immunosuppression. METHODS Mixed lymphocyte reaction (MLR) assay and a mouse heart transplantation model were used to evaluate the immunosuppressive effect of MMF with MZ. The median-effect principle and a combination index (CI) were employed to determine synergism, an additive effect, or antagonism. RESULTS Combination of MMF with MZ resulted in mild synergistic effects in the inhibition of MLR (CI = 0.854-1.143). In the mouse heart transplantation model, C57BL/6 recipients who received a BALB/c heart under the combination of MMF and MZ at 40 + 40 or 80 + 80 mg/kg/day showed a strong synergistic prolongation of graft survival with 19.7 +/- 18.9 (P = 0.0012, CI = 0.438) and 78.4 +/- 36.9 days (P = 0.0002, CI = 0.317), respectively, compared with recipients treated with MMF or MZ monotherapy. CONCLUSIONS.: The combination of MMF and MZ showed mild synergistic effects in the inhibition of MLR and strong synergistic effects in a mouse heart transplantation model.
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Affiliation(s)
- Hiroaki Shimmura
- Department of Urology, Kidney Center, Tokyo Women's Medical University, Shinjuku, Japan
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Franchetti P, Pasqualini M, Cappellacci L, Petrelli R, Vita P, Grifantini M. Ribose-modified mizoribine analogues: synthesis and biological evaluation. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2006; 24:2023-7. [PMID: 16438062 DOI: 10.1080/15257770500334673] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Synthesis, conformational analysis and antitumor evaluation of 2'- and 3'-C-methyl analogues of mizoribine (bredinine, 4-carbamoyl-1-beta-D-ribofuranosylimidazole-5-olate) are reported.
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Li J, Wei Z, Zheng M, Gu X, Deng Y, Qiu R, Chen F, Ji C, Gong W, Xie Y, Mao Y. Crystal structure of human guanosine monophosphate reductase 2 (GMPR2) in complex with GMP. J Mol Biol 2005; 355:980-8. [PMID: 16359702 DOI: 10.1016/j.jmb.2005.11.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 11/04/2005] [Accepted: 11/15/2005] [Indexed: 10/25/2022]
Abstract
Guanosine monophosphate reductase (GMPR) catalyzes the irreversible and NADPH-dependent reductive deamination of GMP to IMP, and plays a critical role in re-utilization of free intracellular bases and purine nucleosides. Here, we report the first crystal structure of human GMP reductase 2 (hGMPR2) in complex with GMP at 3.0 A resolution. The protein forms a tetramer composed of subunits adopting the ubiquitous (alpha/beta)8 barrel fold. Interestingly, the substrate GMP is bound to hGMPR2 through interactions with Met269, Ser270, Arg286, Ser288, and Gly290; this makes the conformation of the adjacent flexible binding region (residues 268-289) fixed, much like a door on a hinge. Structure comparison and sequence alignment analyses show that the conformation of the active site loop (residues 179-187) is similar to those of hGMPR1 and inosine monophosphate dehydrogenases (IMPDHs). We propose that Cys186 is the potential active site, and that the conformation of the loop (residues 129-133) suggests a preference for the coenzyme NADPH over NADH. This structure provides important information towards understanding the functions of members of the GMPR family.
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Affiliation(s)
- Jixi Li
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China
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Seo KW, Lee HK, Choi SJN, So BJ, Kim SK, Chung SY. Mizoribine-mediated apoptotic signaling pathway in human T-Cell line. Transplant Proc 2005; 37:155-8. [PMID: 15808579 DOI: 10.1016/j.transproceed.2005.01.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Mizoribine (MZR), an inhibitor of inosine monophosphate dehydrogenase, which depletes cellular guanadine triphosphate, is an immunosuppressive drug. The aim of this study was to evaluate the mechanism by which MZR exerts cytotoxic effects on human Jurkat T cells. Our study showed that MZR-induced apoptotic death of human Jurkat T cells is dose-dependent and time-dependent, as revealed by chromatin condensation and H2AX phosphorylation. Furthermore, MZR increased the catalytic activity of caspase family cysteine proteases, including caspase-3, caspase-8, and caspase-9, in human Jurkat T cells. In conclusion, MZR induces the apoptotic death of human Jurkat T cells via activation of caspase family proteases as well as by mitochondrial dysfunction.
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Affiliation(s)
- K W Seo
- Division of Transplantation Surgery, Department of Surgery, Chonnam National University Medical School, Gwangju, Korea.
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Sugiyama K, Satoh H, Saito K, Takahashi K, Saito N, Hirano T. Immunosuppressive efficacy of mycophenolate mofetil when compared with azathioprine and mizoribine against peripheral lymphocytes from renal transplant recipients. Transpl Int 2005; 18:590-5. [PMID: 15819809 DOI: 10.1111/j.1432-2277.2005.00093.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: 11/30/2022]
Abstract
Mycophenolate mofetil is currently used instead of azathioprine in clinical transplantation. However, comparative studies for the immunosuppressive potency of anti-metabolites used for organ transplantation have not been well documented. We compared the pharmacological efficacy of mycophenolic acid (MPA), 6-meraputopurine (6-MP), and mizoribine (MZ) for inhibiting purine synthesis of peripheral blood mononuclear cells (PBMCs) in vitro by a mitogen assay procedure. PBMCs were obtained from 18 renal transplant recipients before operation and 18 healthy subjects. The inhibitory efficacy of 6-MP against concanavalin A-induced PBMC blastogenesis exhibited large variations between subjects in both recipients and healthy subjects. In contrast, the pharmacological efficacy of MPA on PBMC blastogenesis showed the smallest inter-individual variation of all the purine synthesis inhibitors examined. Furthermore, the effects of MPA were almost similar in the recipients and healthy subjects. The pharmacological efficacy of MZ against PBMC blastogenesis was weaker than that of the other two agents and the inter-individual variation of MZ IC50 against PBMCs of the patients was larger than that of MZ IC50 against PBMCs of healthy subjects. Reproducible immunosuppressive efficacy of MPA compared with other purinesynthesis inhibitors could be expected from the viewpoint of MPA pharmacodynamics against PBMCs in renal transplantation.
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Affiliation(s)
- Kentaro Sugiyama
- Division of Pharmacy, Niigata University Medical and Dental Hospital, Asahimachi-dori, Niigata City, Niigata, Japan.
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Guillén Schlippe YV, Hedstrom L. A twisted base? The role of arginine in enzyme-catalyzed proton abstractions. Arch Biochem Biophys 2005; 433:266-78. [PMID: 15581582 DOI: 10.1016/j.abb.2004.09.018] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 09/13/2004] [Indexed: 10/26/2022]
Abstract
Arginine residues are generally considered poor candidates for the role of general bases because they are predominantly protonated at physiological pH. Nonetheless, Arg residues have recently emerged as general bases in several enzymes: IMP dehydrogenase, pectate/pectin lyases, fumarate reductase, and l-aspartate oxidase. The experimental evidence suggesting this mechanistic function is reviewed. Although these enzymes have several different folds and distinct evolutionary origins, a common structural motif is found where the critical Arg residue is solvent accessible and adjacent to carboxylate groups. The chemistry of the guanidine group suggests unique strategies to lower the pK(a) of Arg. Lastly, the presumption that general bases must be predominantly deprotonated is revisited.
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50
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Köhler GA, Gong X, Bentink S, Theiss S, Pagani GM, Agabian N, Hedstrom L. The functional basis of mycophenolic acid resistance in Candida albicans IMP dehydrogenase. J Biol Chem 2005; 280:11295-302. [PMID: 15665003 DOI: 10.1074/jbc.m409847200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Candida albicans is an important fungal pathogen of immunocompromised patients. In cell culture, C. albicans is sensitive to mycophenolic acid (MPA) and mizoribine, both natural product inhibitors of IMP dehydrogenase (IMPDH). These drugs have opposing interactions with the enzyme. MPA prevents formation of the closed enzyme conformation by binding to the same site as a mobile flap. In contrast, mizoribine monophosphate, the active metabolite of mizoribine, induces the closed conformation. Here, we report the characterization of IMPDH from wild-type and MPA-resistant strains of C. albicans. The wild-type enzyme displays significant differences from human IMPDHs, suggesting that selective inhibitors that could be novel antifungal agents may be developed. IMPDH from the MPA-resistant strain contains a single substitution (A251T) that is far from the MPA-binding site. The A251T variant was 4-fold less sensitive to MPA as expected. This substitution did not affect the k(cat) value, but did decrease the K(m) values for both substrates, so the mutant enzyme is more catalytically efficient as measured by the value of k(cat)/K(m). These simple criteria suggest that the A251T variant would be the evolutionarily superior enzyme. However, the A251T substitution caused the enzyme to be 40-fold more sensitive to mizoribine monophosphate. This result suggests that A251T stabilizes the closed conformation, and this hypothesis is supported by further inhibitor analysis. Likewise, the MPA-resistant strain was more sensitive to mizoribine in cell culture. These observations illustrate the evolutionary challenge posed by the gauntlet of chemical warfare at the microbial level.
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Affiliation(s)
- Gerwald A Köhler
- Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
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