1
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Yan W, Zheng Y, Dou C, Zhang G, Arnaout T, Cheng W. The pathogenic mechanism of Mycobacterium tuberculosis: implication for new drug development. MOLECULAR BIOMEDICINE 2022; 3:48. [PMID: 36547804 PMCID: PMC9780415 DOI: 10.1186/s43556-022-00106-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/15/2022] [Indexed: 12/24/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a tenacious pathogen that has latently infected one third of the world's population. However, conventional TB treatment regimens are no longer sufficient to tackle the growing threat of drug resistance, stimulating the development of innovative anti-tuberculosis agents, with special emphasis on new protein targets. The Mtb genome encodes ~4000 predicted proteins, among which many enzymes participate in various cellular metabolisms. For example, more than 200 proteins are involved in fatty acid biosynthesis, which assists in the construction of the cell envelope, and is closely related to the pathogenesis and resistance of mycobacteria. Here we review several essential enzymes responsible for fatty acid and nucleotide biosynthesis, cellular metabolism of lipids or amino acids, energy utilization, and metal uptake. These include InhA, MmpL3, MmaA4, PcaA, CmaA1, CmaA2, isocitrate lyases (ICLs), pantothenate synthase (PS), Lysine-ε amino transferase (LAT), LeuD, IdeR, KatG, Rv1098c, and PyrG. In addition, we summarize the role of the transcriptional regulator PhoP which may regulate the expression of more than 110 genes, and the essential biosynthesis enzyme glutamine synthetase (GlnA1). All these enzymes are either validated drug targets or promising target candidates, with drugs targeting ICLs and LAT expected to solve the problem of persistent TB infection. To better understand how anti-tuberculosis drugs act on these proteins, their structures and the structure-based drug/inhibitor designs are discussed. Overall, this investigation should provide guidance and support for current and future pharmaceutical development efforts against mycobacterial pathogenesis.
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Affiliation(s)
- Weizhu Yan
- grid.412901.f0000 0004 1770 1022Division of Respiratory and Critical Care Medicine, Respiratory Infection and Intervention Laboratory of Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041 China
| | - Yanhui Zheng
- grid.412901.f0000 0004 1770 1022Division of Respiratory and Critical Care Medicine, Respiratory Infection and Intervention Laboratory of Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041 China
| | - Chao Dou
- grid.412901.f0000 0004 1770 1022Division of Respiratory and Critical Care Medicine, Respiratory Infection and Intervention Laboratory of Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041 China
| | - Guixiang Zhang
- grid.13291.380000 0001 0807 1581Division of Gastrointestinal Surgery, Department of General Surgery and Gastric Cancer center, West China Hospital, Sichuan University, No. 37. Guo Xue Xiang, Chengdu, 610041 China
| | - Toufic Arnaout
- Kappa Crystals Ltd., Dublin, Ireland ,MSD Dunboyne BioNX, Co. Meath, Ireland
| | - Wei Cheng
- grid.412901.f0000 0004 1770 1022Division of Respiratory and Critical Care Medicine, Respiratory Infection and Intervention Laboratory of Frontiers Science Center for Disease-Related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041 China
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2
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Liang YF, Long ZX, Zhang YJ, Luo CY, Yan LT, Gao WY, Li H. The chemical mechanisms of the enzymes in the branched-chain amino acids biosynthetic pathway and their applications. Biochimie 2021; 184:72-87. [PMID: 33607240 DOI: 10.1016/j.biochi.2021.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/04/2021] [Accepted: 02/10/2021] [Indexed: 12/27/2022]
Abstract
l-Valine, l-isoleucine, and l-leucine are three key proteinogenic amino acids, and they are also the essential amino acids required for mammalian growth, possessing important and to some extent, special physiological and biological functions. Because of the branched structures in their carbon chains, they are also named as branched-chain amino acids (BCAAs). This review will highlight the advance in studies of the enzymes involved in the biosynthetic pathway of BCAAs, concentrating on their chemical mechanisms and applications in screening herbicides and antibacterial agents. The uses of some of these enzymes in lab scale organic synthesis are also discussed.
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Affiliation(s)
- Yan-Fei Liang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Zi-Xian Long
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Ya-Jian Zhang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Cai-Yun Luo
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Le-Tian Yan
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Wen-Yun Gao
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
| | - Heng Li
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
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3
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Miggiano R, Martignon S, Minassi A, Rossi F, Rizzi M. Crystal structure of Haemophilus influenzae 3-isopropylmalate dehydrogenase (LeuB) in complex with the inhibitor O-isobutenyl oxalylhydroxamate. Biochem Biophys Res Commun 2020; 524:996-1002. [DOI: 10.1016/j.bbrc.2020.02.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 11/25/2022]
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4
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Amorim Franco TM, Blanchard JS. Bacterial Branched-Chain Amino Acid Biosynthesis: Structures, Mechanisms, and Drugability. Biochemistry 2017; 56:5849-5865. [PMID: 28977745 DOI: 10.1021/acs.biochem.7b00849] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The eight enzymes responsible for the biosynthesis of the three branched-chain amino acids (l-isoleucine, l-leucine, and l-valine) were identified decades ago using classical genetic approaches based on amino acid auxotrophy. This review will highlight the recent progress in the determination of the three-dimensional structures of these enzymes, their chemical mechanisms, and insights into their suitability as targets for the development of antibacterial agents. Given the enormous rise in bacterial drug resistance to every major class of antibacterial compound, there is a clear and present need for the identification of new antibacterial compounds with nonoverlapping targets to currently used antibacterials that target cell wall, protein, mRNA, and DNA synthesis.
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Affiliation(s)
- Tathyana M Amorim Franco
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10805, United States
| | - John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10805, United States
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5
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Palló A, Oláh J, Gráczer E, Merli A, Závodszky P, Weiss MS, Vas M. Structural and energetic basis of isopropylmalate dehydrogenase enzyme catalysis. FEBS J 2014; 281:5063-76. [PMID: 25211160 DOI: 10.1111/febs.13044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/06/2014] [Accepted: 09/08/2014] [Indexed: 01/17/2023]
Abstract
UNLABELLED The three-dimensional structure of the enzyme 3-isopropylmalate dehydrogenase from the bacterium Thermus thermophilus in complex with Mn(2+) , its substrate isopropylmalate and its co-factor product NADH at 2.0 Å resolution features a fully closed conformation of the enzyme. Upon closure of the two domains, the substrate and the co-factor are brought into precise relative orientation and close proximity, with a distance between the C2 atom of the substrate and the C4N atom of the pyridine ring of the co-factor of approximately 3.0 Å. The structure further shows binding of a K(+) ion close to the active site, and provides an explanation for its known activating effect. Hence, this structure is an excellent mimic for the enzymatically competent complex. Using high-level QM/MM calculations, it may be demonstrated that, in the observed arrangement of the reactants, transfer of a hydride from the C2 atom of 3-isopropylmalate to the C4N atom of the pyridine ring of NAD(+) is easily possible, with an activation energy of approximately 15 kcal·mol(-1) . The activation energy increases by approximately 4-6 kcal·mol(-1) when the K(+) ion is omitted from the calculations. In the most plausible scenario, prior to hydride transfer the ε-amino group of Lys185 acts as a general base in the reaction, aiding the deprotonation reaction of 3-isopropylmalate prior to hydride transfer by employing a low-barrier proton shuttle mechanism involving a water molecule. DATABASE Structural data have been submitted to the Protein Data Bank under accession number 4F7I.
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Affiliation(s)
- Anna Palló
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
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6
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Gráczer É, Lionne C, Závodszky P, Chaloin L, Vas M. Transient kinetic studies reveal isomerization steps along the kinetic pathway ofThermus thermophilus3-isopropylmalate dehydrogenase. FEBS J 2013; 280:1764-72. [DOI: 10.1111/febs.12191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/08/2013] [Accepted: 02/11/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Éva Gráczer
- Institute of Enzymology; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest; Hungary
| | - Corinne Lionne
- Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS); UMR 5236 CNRS; University Montpellier I, University Montpellier II; France
| | - Péter Závodszky
- Institute of Enzymology; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest; Hungary
| | - Laurent Chaloin
- Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS); UMR 5236 CNRS; University Montpellier I, University Montpellier II; France
| | - Mária Vas
- Institute of Enzymology; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest; Hungary
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7
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He Y, Galant A, Pang Q, Strul JM, Balogun SF, Jez JM, Chen S. Structural and functional evolution of isopropylmalate dehydrogenases in the leucine and glucosinolate pathways of Arabidopsis thaliana. J Biol Chem 2011; 286:28794-28801. [PMID: 21697089 DOI: 10.1074/jbc.m111.262519] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The methionine chain-elongation pathway is required for aliphatic glucosinolate biosynthesis in plants and evolved from leucine biosynthesis. In Arabidopsis thaliana, three 3-isopropylmalate dehydrogenases (AtIPMDHs) play key roles in methionine chain-elongation for the synthesis of aliphatic glucosinolates (e.g. AtIPMDH1) and leucine (e.g. AtIPMDH2 and AtIPMDH3). Here we elucidate the molecular basis underlying the metabolic specialization of these enzymes. The 2.25 Å resolution crystal structure of AtIPMDH2 was solved to provide the first detailed molecular architecture of a plant IPMDH. Modeling of 3-isopropylmalate binding in the AtIPMDH2 active site and sequence comparisons of prokaryotic and eukaryotic IPMDH suggest that substitution of one active site residue may lead to altered substrate specificity and metabolic function. Site-directed mutagenesis of Phe-137 to a leucine in AtIPMDH1 (AtIPMDH1-F137L) reduced activity toward 3-(2'-methylthio)ethylmalate by 200-fold, but enhanced catalytic efficiency with 3-isopropylmalate to levels observed with AtIPMDH2 and AtIPMDH3. Conversely, the AtIPMDH2-L134F and AtIPMDH3-L133F mutants enhanced catalytic efficiency with 3-(2'-methylthio)ethylmalate ∼100-fold and reduced activity for 3-isopropylmalate. Furthermore, the altered in vivo glucosinolate profile of an Arabidopsis ipmdh1 T-DNA knock-out mutant could be restored to wild-type levels by constructs expressing AtIPMDH1, AtIPMDH2-L134F, or AtIPMDH3-L133F, but not by AtIPMDH1-F137L. These results indicate that a single amino acid substitution results in functional divergence of IPMDH in planta to affect substrate specificity and contributes to the evolution of specialized glucosinolate biosynthesis from the ancestral leucine pathway.
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Affiliation(s)
- Yan He
- Department of Biology, Genetics Institute, Plant Molecular, and Cellular Biology Program, University of Florida, Gainesville, Florida 32610 and
| | - Ashley Galant
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Qiuying Pang
- Department of Biology, Genetics Institute, Plant Molecular, and Cellular Biology Program, University of Florida, Gainesville, Florida 32610 and
| | - Johanna M Strul
- Department of Biology, Genetics Institute, Plant Molecular, and Cellular Biology Program, University of Florida, Gainesville, Florida 32610 and
| | | | - Joseph M Jez
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Sixue Chen
- Department of Biology, Genetics Institute, Plant Molecular, and Cellular Biology Program, University of Florida, Gainesville, Florida 32610 and.
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8
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Gráczer É, Merli A, Singh RK, Karuppasamy M, Závodszky P, Weiss MS, Vas M. Atomic level description of the domain closure in a dimeric enzyme: thermus thermophilus 3-isopropylmalate dehydrogenase. MOLECULAR BIOSYSTEMS 2011; 7:1646-59. [PMID: 21387033 DOI: 10.1039/c0mb00346h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The domain closure associated with the catalytic cycle is described at an atomic level, based on pairwise comparison of the X-ray structures of homodimeric Thermus thermophilus isopropylmalate dehydrogenase (IPMDH), and on their detailed molecular graphical analysis. The structures of the apo-form without substrate and in complex with the divalent metal-ion to 1.8 Å resolution, in complexes with both Mn(2+) and 3-isopropylmalate (IPM), as well as with both Mn(2+) and NADH, were determined at resolutions ranging from 2.0 to 2.5 Å. Single crystal microspectrophotometric measurements demonstrated the presence of a functionally competent protein conformation in the crystal grown in the presence of Mn(2+) and IPM. Structural comparison of the various complexes clearly revealed the relative movement of the two domains within each subunit and allowed the identification of two hinges at the interdomain region: hinge 1 between αd and βF as well as hinge 2 between αh and βE. A detailed analysis of the atomic contacts of the conserved amino acid side-chains suggests a possible operational mechanism of these molecular hinges upon the action of the substrates. The interactions of the protein with Mn(2+) and IPM are mainly responsible for the domain closure: upon binding into the cleft of the interdomain region, the substrate IPM induces a relative movement of the secondary structural elements βE, βF, βG, αd and αh. A further special feature of the conformational change is the movement of the loop bearing the amino acid Tyr139 that precedes the interacting arm of the subunit. The tyrosyl ring rotates and moves by at least 5 Å upon IPM-binding. Thereby, new hydrophobic interactions are formed above the buried isopropyl-group of IPM. Domain closure is then completed only through subunit interactions: a loop of one subunit that is inserted into the interdomain cavity of the other subunit extends the area with the hydrophobic interactions, providing an example of the cooperativity between interdomain and intersubunit interactions.
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Affiliation(s)
- Éva Gráczer
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, PO Box 7, H1518 Budapest, Hungary
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9
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Mueller-Dieckmann C, Kauffmann B, Weiss MS. TrimethylamineN-oxide as a versatile cryoprotective agent in macromolecular crystallography. J Appl Crystallogr 2011. [DOI: 10.1107/s0021889811000045] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The surge of macromolecular crystallography is intimately linked to the advent of methods for cryoprotecting macromolecular crystals. Only if crystals are kept cold during data collection can they withstand the effects of radiation damage during a diffraction experiment, especially at third-generation synchrotron sources. While a number of different cryoprotective agents and procedures have been described in the literature over the past three decades, it is still a time- and crystal-consuming process to establish and optimize a good cryo-condition for a specific crystal. In this study, trimethylamineN-oxide (TMAO) has been identified as a very versatile cryoprotectant for macromolecular crystals. In a few test cases it was shown that diffraction data collected from crystals treated with TMAO are of very good quality.
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10
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Manikandan K, Geerlof A, Zozulya AV, Svergun DI, Weiss MS. Structural studies on the enzyme complex isopropylmalate isomerase (LeuCD) fromMycobacterium tuberculosis. Proteins 2010; 79:35-49. [DOI: 10.1002/prot.22856] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/08/2010] [Accepted: 07/25/2010] [Indexed: 11/10/2022]
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11
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Merli A, Manikandan K, Gráczer É, Schuldt L, Singh RK, Závodszky P, Vas M, Weiss MS. Crystallization and preliminary X-ray diffraction analysis of various enzyme-substrate complexes of isopropylmalate dehydrogenase from Thermus thermophilus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:738-43. [PMID: 20516614 PMCID: PMC2882784 DOI: 10.1107/s174430911001626x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 05/03/2010] [Indexed: 11/10/2022]
Abstract
The Thermus thermophilus 3-isopropylmalate dehydrogenase (Tt-IPMDH) enzyme catalyses the penultimate step of the leucine-biosynthesis pathway. It converts (2R,3S)-3-isopropylmalate to (2S)-2-isopropyl-3-oxosuccinate in the presence of divalent Mg(2+) or Mn(2+) and with the help of NAD(+). In order to elucidate the detailed structural and functional mode of the enzymatic reaction, crystals of Tt-IPMDH were grown in the presence of various combinations of substrate and/or cofactors. Here, the crystallization, data collection and preliminary crystallographic analyses of six such complexes are reported.
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Affiliation(s)
- Angelo Merli
- Department of Biochemistry and Molecular Biology, University of Parma, Viale G. P. Usberti 23/A, 43100 Parma, Italy
| | | | - Éva Gráczer
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H1518 Budapest, PO Box 7, Hungary
| | - Linda Schuldt
- EMBL Hamburg Outstation, c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany
| | | | - Péter Závodszky
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H1518 Budapest, PO Box 7, Hungary
| | - Mária Vas
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H1518 Budapest, PO Box 7, Hungary
| | - Manfred S. Weiss
- EMBL Hamburg Outstation, c/o DESY, Notkestrasse 85, D-22603 Hamburg, Germany
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12
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Nango E, Yamamoto T, Kumasaka T, Eguchi T. Crystal structure of 3-isopropylmalate dehydrogenase in complex with NAD(+) and a designed inhibitor. Bioorg Med Chem 2009; 17:7789-94. [PMID: 19833522 DOI: 10.1016/j.bmc.2009.09.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 09/12/2009] [Accepted: 09/15/2009] [Indexed: 10/20/2022]
Abstract
Isopropylmalate dehydrogenase (IPMDH) is the third enzyme specific to leucine biosynthesis in microorganisms and plants, and catalyzes the oxidative decarboxylation of (2R,3S)-3-isopropylmalate to alpha-ketoisocaproate using NAD(+) as an oxidizing agent. In this study, a thia-analogue of the substrate was designed and synthesized as an inhibitor for IPMDH. The analogue showed strong competitive inhibitory activity with K(i)=62nM toward IPMDH derived from Thermus thermophilus. Moreover, the crystal structure of T. thermophilus IPMDH in a ternary complex with NAD(+) and the inhibitor has been determined at 2.8A resolution. The inhibitor exists as a decarboxylated product with an enol/enolate form in the active site. The product interacts with Arg 94, Asn 102, Ser 259, Glu 270, and a water molecule hydrogen-bonding with Arg 132. All interactions between the product and the enzyme were observed in the position associated with keto-enol tautomerization. This result implies that the tautomerization step of the thia-analogue during the IPMDH reaction is involved in the inhibition.
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Affiliation(s)
- Eriko Nango
- Department of Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8551, Japan
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13
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Hajdú I, Szilágyi A, Kardos J, Závodszky P. A link between hinge-bending domain motions and the temperature dependence of catalysis in 3-isopropylmalate dehydrogenase. Biophys J 2009; 96:5003-12. [PMID: 19527660 DOI: 10.1016/j.bpj.2009.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 03/31/2009] [Accepted: 04/01/2009] [Indexed: 10/20/2022] Open
Abstract
Enzyme function depends on specific conformational motions. We show that the temperature dependence of enzyme kinetic parameters can provide insight into these functionally relevant motions. While investigating the catalytic properties of IPMDH from Escherichia coli, we found that its catalytic efficiency (k(cat)/K(M,IPM)) for the substrate IPM has an unusual temperature dependence, showing a local minimum at approximately 35 degrees C. In search of an explanation, we measured the individual constants k(cat) and K(M,IPM) as a function of temperature, and found that the van 't Hoff plot of K(M,IPM) shows sigmoid-like transition in the 20-40 degrees C temperature range. By means of various measurements including hydrogen-deuterium exchange and fluorescence resonance energy transfer, we showed that the conformational fluctuations, including hinge-bending domain motions increase more steeply with temperatures >30 degrees C. The thermodynamic parameters of ligand binding determined by isothermal titration calorimetry as a function of temperature were found to be strongly correlated to the conformational fluctuations of the enzyme. Because the binding of IPM is associated with a hinge-bending domain closure, the more intense hinge-bending fluctuations at higher temperatures increasingly interfere with IPM binding, thereby abruptly increasing its dissociation constant and leading to the observed unusual temperature dependence of the catalytic efficiency.
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Affiliation(s)
- István Hajdú
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary
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14
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Gráczer É, Varga A, Melnik B, Semisotnov G, Závodszky P, Vas M. Symmetrical Refolding of Protein Domains and Subunits: Example of the Dimeric Two-Domain 3-Isopropylmalate Dehydrogenases. Biochemistry 2009; 48:1123-34. [DOI: 10.1021/bi801857t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Éva Gráczer
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Andrea Varga
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Bogdan Melnik
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Gennady Semisotnov
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Péter Závodszky
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | - Mária Vas
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary, and Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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15
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Gráczer E, Varga A, Hajdú I, Melnik B, Szilágyi A, Semisotnov G, Závodszky P, Vas M. Rates of unfolding, rather than refolding, determine thermal stabilities of thermophilic, mesophilic, and psychrotrophic 3-isopropylmalate dehydrogenases. Biochemistry 2007; 46:11536-49. [PMID: 17887729 DOI: 10.1021/bi700754q] [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: 01/31/2023]
Abstract
The relationship between the thermal stability of proteins and rates of unfolding and refolding is still an open issue. The data are very scarce, especially for proteins with complex structure. Here, time-dependent denaturation-renaturation experiments on Thermus thermophilus, Escherichia coli, and Vibrio sp. I5 3-isopropylmalate dehydrogenases (IPMDHs) of different heat stabilities are presented. Unfolding, as monitored by several methods, occurs in a single first-order step with half-times of approximately 1 h, several minutes, and few seconds for the thermophilic, mesophilic, and psychrotrophic enzymes, respectively. The binding of Mn*IPM (the manganese complex of 3-isopropylmalate) markedly reduces the rates of unfolding; this effect is more prominent for the less stable enzyme variants. Refolding is a two-step or multistep first-order process involving an inactive intermediate(s). The restoration of the native structure and reactivation take place with a half-time of a few minutes for all three IPMDHs. Thus, the comparative experimental unfolding-refolding studies of the three IPMDHs with different thermostabilities have revealed a close relationship between thermostability and unfolding rate. Structural analysis has shown that the differences in the molecular contacts between selected nonconserved residues are responsible for the different rates of unfolding. On the other hand, the folding rates might be correlated with the absolute contact order, which does not significantly vary between IPMDHs with different thermostabilities. On the basis of our observations, folding rates appear to be dictated by global structural characteristics (such as native topology, i.e., contact order) rather than by thermodynamic stability.
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Affiliation(s)
- Eva Gráczer
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary
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16
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McCourt JA, Duggleby RG. Acetohydroxyacid synthase and its role in the biosynthetic pathway for branched-chain amino acids. Amino Acids 2006; 31:173-210. [PMID: 16699828 DOI: 10.1007/s00726-005-0297-3] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 12/09/2005] [Indexed: 11/25/2022]
Abstract
The branched-chain amino acids are synthesized by plants, fungi and microorganisms, but not by animals. Therefore, the enzymes of this pathway are potential target sites for the development of antifungal agents, antimicrobials and herbicides. Most research has focused upon the first enzyme in this biosynthetic pathway, acetohydroxyacid synthase (AHAS) largely because it is the target site for many commercial herbicides. In this review we provide a brief overview of the important properties of each enzyme within the pathway and a detailed summary of the most recent AHAS research, against the perspective of work that has been carried out over the past 50 years.
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Affiliation(s)
- J A McCourt
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Australia
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Arcus VL, Lott JS, Johnston JM, Baker EN. The potential impact of structural genomics on tuberculosis drug discovery. Drug Discov Today 2006; 11:28-34. [PMID: 16478688 DOI: 10.1016/s1359-6446(05)03667-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) in humans, is a devastating infectious organism that kills approximately two million people annually. The current suite of antibiotics used to treat TB faces two main difficulties: (i) the emergence of multidrug-resistant (MDR) strains of M. tuberculosis, and (ii) the persistent state of the bacterium, which is less susceptible to antibiotics and causes very long antibiotic treatment regimes. The complete genome sequences of a laboratory strain (H37Rv) and a clinical strain (CDC1551) of M. tuberculosis and the concurrent identification of all the open reading frames that encode proteins within this organism, present structural biologists with a wide array of protein targets for structure determination. Comparative genomics of the species that make up the M. tuberculosis complex has also added an array of genomic information to our understanding of these organisms. In response to this, structural genomics consortia have been established for targeting proteins from M. tuberculosis. This review looks at the progress of these major initiatives and the potential impact of large scale structure determination efforts on the development of inhibitors to many proteins. Increasing sophistication in structure-based drug design approaches, in combination with increasing numbers of protein structures and inhibitors for TB proteins, will have a significant impact on the downstream development of TB antibiotics.
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Affiliation(s)
- Vickery L Arcus
- AgResearch Structural Biology Laboratory, School of Biological Sciences, University of Auckland, Private Bag 92-019, Auckland, New Zealand.
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