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Meelua W, Wanjai T, Thinkumrob N, Oláh J, Cairns JRK, Hannongbua S, Ryde U, Jitonnom J. A computational study of the reaction mechanism and stereospecificity of dihydropyrimidinase. Phys Chem Chem Phys 2023; 25:8767-8778. [PMID: 36912034 DOI: 10.1039/d2cp05262h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Dihydropyrimidinase (DHPase) is a key enzyme in the pyrimidine pathway, the catabolic route for synthesis of β-amino acids. It catalyses the reversible conversion of 5,6-dihydrouracil (DHU) or 5,6-dihydrothymine (DHT) to the corresponding N-carbamoyl-β-amino acids. This enzyme has the potential to be used as a tool in the production of β-amino acids. Here, the reaction mechanism and origin of stereospecificity of DHPases from Saccharomyces kluyveri and Sinorhizobium meliloti CECT4114 were investigated and compared using a quantum mechanical cluster approach based on density functional theory. Two models of the enzyme active site were designed from the X-ray crystal structure of the native enzyme: a small cluster to characterize the mechanism and the stationary points and a large model to probe the stereospecificity and the role of stereo-gate-loop (SGL) residues. It is shown that a hydroxide ion first performs a nucleophilic attack on the substrate, followed by the abstraction of a proton by Asp358, which occurs concertedly with protonation of the ring nitrogen by the same residue. For the DHT substrate, the enzyme displays a preference for the L-configuration, in good agreement with experimental observation. Comparison of the reaction energetics of the two models reveals the importance of SGL residues in the stereospecificity of catalysis. The role of the conserved Tyr172 residue in transition-state stabilization is confirmed as the Tyr172Phe mutation increases the activation barrier of the reaction by ∼8 kcal mol-1. A detailed understanding of the catalytic mechanism of the enzyme could offer insight for engineering in order to enhance its activity and substrate scope.
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Affiliation(s)
- Wijitra Meelua
- Demonstration School, University of Phayao, Phayao 56000, Thailand
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Tanchanok Wanjai
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Natechanok Thinkumrob
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Julianna Oláh
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3, Budapest H-1111, Hungary
| | - James R Ketudat Cairns
- Center for Biomolecular Structure, Function and Application and School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Supa Hannongbua
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, Lund SE-221 00, Sweden
| | - Jitrayut Jitonnom
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
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Lin ES, Huang YH, Yang PC, Peng WF, Huang CY. Complexed Crystal Structure of the Dihydroorotase Domain of Human CAD Protein with the Anticancer Drug 5-Fluorouracil. Biomolecules 2023; 13:149. [PMID: 36671534 PMCID: PMC9856072 DOI: 10.3390/biom13010149] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/05/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Dihydroorotase (DHOase) is the third enzyme in the pathway used for the biosynthesis of pyrimidine nucleotides. In mammals, DHOase is active in a trifunctional enzyme, CAD, which also carries out the activities of carbamoyl phosphate synthetase and aspartate transcarbamoylase. Prior to this study, it was unknown whether the FDA-approved clinical drug 5-fluorouracil (5-FU), which is used as an anticancer therapy, could bind to the DHOase domain of human CAD (huDHOase). Here, we identified huDHOase as a new 5-FU binding protein, thereby extending the 5-FU interactome to this human enzyme. In order to investigate where 5-FU binds to huDHOase, we solved the complexed crystal structure at 1.97 Å (PDB ID 8GVZ). The structure of huDHOase complexed with malate was also determined for the sake of comparison (PDB ID 8GW0). These two nonsubstrate ligands were bound at the active site of huDHOase. It was previously established that the substrate N-carbamoyl-L-aspartate is either bound to or moves away from the active site, but it is the loop that is extended towards (loop-in mode) or moved away (loop-out mode) from the active site. DHOase also binds to nonsubstrate ligands via the loop-out mode. In contrast to the Escherichia coli DHOase model, our complexed structures revealed that huDHOase binds to either 5-FU or malate via the loop-in mode. We further characterized the binding of 5-FU to huDHOase using site-directed mutagenesis and the fluorescence quenching method. Considering the loop-in mode, the dynamic loop in huDHOase should be a suitable drug-targeting site for further designing inhibitors and clinical chemotherapies to suppress pyrimidine biosynthesis in cancer cell lines.
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Affiliation(s)
- En-Shyh Lin
- Department of Beauty Science, National Taichung University of Science and Technology, Taichung City 403, Taiwan
| | - Yen-Hua Huang
- Department of Beauty Science, National Taichung University of Science and Technology, Taichung City 403, Taiwan
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Po-Chun Yang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
| | - Wei-Feng Peng
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medicine, College of Medicine, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Pediatrics, National Taiwan University Children’s Hospital, Taipei 100, Taiwan
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung City 402, Taiwan
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3
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Complexed Crystal Structure of Saccharomyces cerevisiae Dihydroorotase with Inhibitor 5-Fluoroorotate Reveals a New Binding Mode. Bioinorg Chem Appl 2021; 2021:2572844. [PMID: 34630544 PMCID: PMC8497156 DOI: 10.1155/2021/2572844] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/30/2021] [Accepted: 09/14/2021] [Indexed: 02/08/2023] Open
Abstract
Dihydroorotase (DHOase) possesses a binuclear metal center in which two Zn ions are bridged by a posttranslationally carbamylated lysine. DHOase catalyzes the reversible cyclization of N-carbamoyl aspartate (CA-asp) to dihydroorotate (DHO) in the third step of the pathway for the biosynthesis of pyrimidine nucleotides and is an attractive target for potential anticancer and antimalarial chemotherapy. Crystal structures of ligand-bound DHOase show that the flexible loop extends toward the active site when CA-asp is bound (loop-in mode) or moves away from the active site, facilitating the product DHO release (loop-out mode). DHOase binds the product-like inhibitor 5-fluoroorotate (5-FOA) in a similar mode to DHO. In the present study, we report the crystal structure of DHOase from Saccharomyces cerevisiae (ScDHOase) complexed with 5-FOA at 2.5 Å resolution (PDB entry 7CA0). ScDHOase shares structural similarity with Escherichia coli DHOase (EcDHOase). However, our complexed structure revealed that ScDHOase bound 5-FOA differently from EcDHOase. 5-FOA ligated the Zn atoms in the active site of ScDHOase. In addition, 5-FOA bound to ScDHOase through the loop-in mode. We also characterized the binding of 5-FOA to ScDHOase by using the site-directed mutagenesis and fluorescence quenching method. Based on these lines of molecular evidence, we discussed whether these different binding modes are species- or crystallography-dependent.
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Lipowska J, Miks CD, Kwon K, Shuvalova L, Zheng H, Lewiński K, Cooper DR, Shabalin IG, Minor W. Pyrimidine biosynthesis in pathogens - Structures and analysis of dihydroorotases from Yersinia pestis and Vibrio cholerae. Int J Biol Macromol 2019; 136:1176-1187. [PMID: 31207330 PMCID: PMC6686667 DOI: 10.1016/j.ijbiomac.2019.05.149] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/01/2019] [Accepted: 05/14/2019] [Indexed: 02/06/2023]
Abstract
The de novo pyrimidine biosynthesis pathway is essential for the proliferation of many pathogens. One of the pathway enzymes, dihydroorotase (DHO), catalyzes the reversible interconversion of N-carbamoyl-l-aspartate to 4,5-dihydroorotate. The substantial difference between bacterial and mammalian DHOs makes it a promising drug target for disrupting bacterial growth and thus an important candidate to evaluate as a response to antimicrobial resistance on a molecular level. Here, we present two novel three-dimensional structures of DHOs from Yersinia pestis (YpDHO), the plague-causing pathogen, and Vibrio cholerae (VcDHO), the causative agent of cholera. The evaluations of these two structures led to an analysis of all available DHO structures and their classification into known DHO types. Comparison of all the DHO active sites containing ligands that are listed in DrugBank was facilitated by a new interactive, structure-comparison and presentation platform. In addition, we examined the genetic context of characterized DHOs, which revealed characteristic patterns for different types of DHOs. We also generated a homology model for DHO from Plasmodium falciparum.
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Affiliation(s)
- Joanna Lipowska
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID), Charlottesville, VA 22908, USA; Faculty of Chemistry, Jagiellonian University, 30-387 Kraków, Poland
| | - Charles Dylan Miks
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
| | - Keehwan Kwon
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, MD 20850, USA
| | - Ludmilla Shuvalova
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Heping Zheng
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID), Charlottesville, VA 22908, USA
| | | | - David R Cooper
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID), Charlottesville, VA 22908, USA
| | - Ivan G Shabalin
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID), Charlottesville, VA 22908, USA.
| | - Wladek Minor
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID), Charlottesville, VA 22908, USA.
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Del Caño-Ochoa F, Grande-García A, Reverte-López M, D'Abramo M, Ramón-Maiques S. Characterization of the catalytic flexible loop in the dihydroorotase domain of the human multi-enzymatic protein CAD. J Biol Chem 2018; 293:18903-18913. [PMID: 30315107 DOI: 10.1074/jbc.ra118.005494] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/08/2018] [Indexed: 11/06/2022] Open
Abstract
The dihydroorotase (DHOase) domain of the multifunctional protein carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase (CAD) catalyzes the third step in the de novo biosynthesis of pyrimidine nucleotides in animals. The crystal structure of the DHOase domain of human CAD (huDHOase) revealed that, despite evolutionary divergence, its active site components are highly conserved with those in bacterial DHOases, encoded as monofunctional enzymes. An important element for catalysis, conserved from Escherichia coli to humans, is a flexible loop that closes as a lid over the active site. Here, we combined mutagenic, structural, biochemical, and molecular dynamics analyses to characterize the function of the flexible loop in the activity of CAD's DHOase domain. A huDHOase chimera bearing the E. coli DHOase flexible loop was inactive, suggesting the presence of distinctive elements in the flexible loop of huDHOase that cannot be replaced by the bacterial sequence. We pinpointed Phe-1563, a residue absolutely conserved at the tip of the flexible loop in CAD's DHOase domain, as a critical element for the conformational equilibrium between the two catalytic states of the protein. Substitutions of Phe-1563 with Ala, Leu, or Thr prevented the closure of the flexible loop and inactivated the protein, whereas substitution with Tyr enhanced the interactions of the loop in the closed position and reduced fluctuations and the reaction rate. Our results confirm the importance of the flexible loop in CAD's DHOase domain and explain the key role of Phe-1563 in configuring the active site and in promoting substrate strain and catalysis.
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Affiliation(s)
- Francisco Del Caño-Ochoa
- From the Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid 28049, Spain
| | - Araceli Grande-García
- the Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain, and
| | - María Reverte-López
- From the Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid 28049, Spain
| | - Marco D'Abramo
- the Department of Chemistry, Sapienza University of Rome, Rome 00185, Italy
| | - Santiago Ramón-Maiques
- From the Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid 28049, Spain,
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Ca-asp bound X-ray structure and inhibition of Bacillus anthracis dihydroorotase (DHOase). Bioorg Med Chem 2016; 24:4536-4543. [PMID: 27499369 DOI: 10.1016/j.bmc.2016.07.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 01/01/2023]
Abstract
Dihydroorotase (DHOase) is the third enzyme in the de novo pyrimidine synthesis pathway and is responsible for the reversible cyclization of carbamyl-aspartate (Ca-asp) to dihydroorotate (DHO). DHOase is further divided into two classes based on several structural characteristics, one of which is the length of the flexible catalytic loop that interacts with the substrate, Ca-asp, regulating the enzyme activity. Here, we present the crystal structure of Class I Bacillus anthracis DHOase with Ca-asp in the active site, which shows the peptide backbone of glycine in the shorter loop forming the necessary hydrogen bonds with the substrate, in place of the two threonines found in Class II DHOases. Despite the differences in the catalytic loop, the structure confirms that the key interactions between the substrate and active site residues are similar between Class I and Class II DHOase enzymes, which we further validated by mutagenesis studies. B. anthracis DHOase is also a potential antibacterial drug target. In order to identify prospective inhibitors, we performed high-throughput screening against several libraries using a colorimetric enzymatic assay and an orthogonal fluorescence thermal binding assay. Surface plasmon resonance was used for determining binding affinity (KD) and competition analysis with Ca-asp. Our results highlight that the primary difference between Class I and Class II DHOase is the catalytic loop. We also identify several compounds that can potentially be further optimized as potential B. anthracis inhibitors.
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Abstract
We review literature on the metabolism of ribo- and deoxyribonucleotides, nucleosides, and nucleobases in Escherichia coli and Salmonella,including biosynthesis, degradation, interconversion, and transport. Emphasis is placed on enzymology and regulation of the pathways, at both the level of gene expression and the control of enzyme activity. The paper begins with an overview of the reactions that form and break the N-glycosyl bond, which binds the nucleobase to the ribosyl moiety in nucleotides and nucleosides, and the enzymes involved in the interconversion of the different phosphorylated states of the nucleotides. Next, the de novo pathways for purine and pyrimidine nucleotide biosynthesis are discussed in detail.Finally, the conversion of nucleosides and nucleobases to nucleotides, i.e.,the salvage reactions, are described. The formation of deoxyribonucleotides is discussed, with emphasis on ribonucleotidereductase and pathways involved in fomation of dUMP. At the end, we discuss transport systems for nucleosides and nucleobases and also pathways for breakdown of the nucleobases.
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Structures of bacterial kynurenine formamidase reveal a crowded binuclear zinc catalytic site primed to generate a potent nucleophile. Biochem J 2014; 462:581-9. [PMID: 24942958 PMCID: PMC4243253 DOI: 10.1042/bj20140511] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tryptophan is an important precursor for chemical entities that ultimately support the biosynthesis of key metabolites. The second stage of tryptophan catabolism is catalysed by kynurenine formamidase, an enzyme that is different between eukaryotes and prokaryotes. In the present study, we characterize the catalytic properties and present the crystal structures of three bacterial kynurenine formamidases. The structures reveal a new amidase protein fold, a highly organized and distinctive binuclear Zn2+ catalytic centre in a confined, hydrophobic and relatively rigid active site. The structure of a complex with 2-aminoacetophenone delineates aspects of molecular recognition extending to the observation that the substrate itself may be conformationally restricted to assist binding in the confined space of the active site and for subsequent processing. The cations occupy a crowded environment, and, unlike most Zn2+-dependent enzymes, there is little scope to increase co-ordination number during catalysis. We propose that the presence of a bridging water/hydroxide ligand in conjunction with the placement of an active site histidine supports a distinctive amidation mechanism. Catalytic properties and structures of three bacterial kynurenine formamidases are presented. The dimeric enzyme possesses an uncommon fold and crowded binuclear zinc active site. Fluorescence and structure of a complex inform on molecular recognition and a plausible mechanism is proposed.
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Grande-García A, Lallous N, Díaz-Tejada C, Ramón-Maiques S. Structure, functional characterization, and evolution of the dihydroorotase domain of human CAD. Structure 2013; 22:185-98. [PMID: 24332717 DOI: 10.1016/j.str.2013.10.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/28/2013] [Accepted: 10/30/2013] [Indexed: 12/30/2022]
Abstract
Upregulation of CAD, the multifunctional protein that initiates and controls the de novo biosynthesis of pyrimidines in animals, is essential for cell proliferation. Deciphering the architecture and functioning of CAD is of interest for its potential usage as an antitumoral target. However, there is no detailed structural information about CAD other than that it self-assembles into hexamers of ∼1.5 MDa. Here we report the crystal structure and functional characterization of the dihydroorotase domain of human CAD. Contradicting all assumptions, the structure reveals an active site enclosed by a flexible loop with two Zn²⁺ ions bridged by a carboxylated lysine and a third Zn coordinating a rare histidinate ion. Site-directed mutagenesis and functional assays prove the involvement of the Zn and flexible loop in catalysis. Comparison with homologous bacterial enzymes supports a reclassification of the DHOase family and provides strong evidence against current models of the architecture of CAD.
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Affiliation(s)
- Araceli Grande-García
- Structural Bases of Genome Integrity Group, Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Nada Lallous
- Structural Bases of Genome Integrity Group, Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Celsa Díaz-Tejada
- Structural Bases of Genome Integrity Group, Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Santiago Ramón-Maiques
- Structural Bases of Genome Integrity Group, Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain.
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Hsieh YC, Chen MC, Hsu CC, Chan SI, Yang YS, Chen CJ. Crystal structures of vertebrate dihydropyrimidinase and complexes from Tetraodon nigroviridis with lysine carbamylation: metal and structural requirements for post-translational modification and function. J Biol Chem 2013; 288:30645-30658. [PMID: 24005677 DOI: 10.1074/jbc.m113.496778] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Lysine carbamylation, a post-translational modification, facilitates metal coordination for specific enzymatic activities. We have determined structures of the vertebrate dihydropyrimidinase from Tetraodon nigroviridis (TnDhp) in various states: the apoenzyme as well as two forms of the holoenzyme with one and two metals at the catalytic site. The essential active-site structural requirements have been identified for the possible existence of four metal-mediated stages of lysine carbamylation. Only one metal is sufficient for stabilizing lysine carbamylation; however, the post-translational lysine carbamylation facilitates additional metal coordination for the regulation of specific enzymatic activities through controlling the conformations of two dynamic loops, Ala(69)-Arg(74) and Met(158)-Met(165), located in the tunnel for the substrate entrance. The substrate/product tunnel is in the "open form" in the apo-TnDhp, in the "intermediate state" in the monometal TnDhp, and in the "closed form" in the dimetal TnDhp structure, respectively. Structural comparison also suggests that the C-terminal tail plays a role in the enzymatic function through interactions with the Ala(69)-Arg(74) dynamic loop. In addition, the structures of the dimetal TnDhp in complexes with hydantoin, N-carbamyl-β-alanine, and N-carbamyl-β-amino isobutyrate as well as apo-TnDhp in complex with a product analog, N-(2-acetamido)-iminodiacetic acid, have been determined. These structural results illustrate how a protein exploits unique lysines and the metal distribution to accomplish lysine carbamylation as well as subsequent enzymatic functions.
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Affiliation(s)
- Yin-Cheng Hsieh
- From the Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Mei-Chun Chen
- the Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Ching-Chen Hsu
- the Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Sunney I Chan
- the Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan,; the Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 911525
| | - Yuh-Shyong Yang
- the Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan,.
| | - Chun-Jung Chen
- From the Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan,; the Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan, and; the Institute of Biotechnology and; University Center for Bioscience and Biotechnology, National Cheng Kung University, 1 University Road, Tainan City 701, Taiwan.
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Structural switching of Cu,Zn-superoxide dismutases at loop VI: insights from the crystal structure of 2-mercaptoethanol-modified enzyme. Biosci Rep 2013; 32:539-48. [PMID: 22804629 PMCID: PMC3497728 DOI: 10.1042/bsr20120029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cu,Zn SOD1 (superoxide dismutase 1) is implicated in FALS (familial amyotrophic lateral sclerosis) through the accumulation of misfolded proteins that are toxic to neuronal cells. Loop VI (residues 102-115) of the protein is at the dimer interface and could play a critical role in stability. The free cysteine residue, Cys111 in the loop, is readily oxidized and alkylated. We have found that modification of this Cys111 with 2-ME (2-mercaptoethanol; 2-ME-SOD1) stabilizes the protein and the mechanism may provide insights into destabilization and the formation of aggregated proteins. Here, we determined the crystal structure of 2-ME-SOD1 and find that the 2-ME moieties in both subunits interact asymmetrically at the dimer interface and that there is an asymmetric configuration of segment Gly108 to Cys111 in loop VI. One loop VI of the dimer forms a 310-helix (Gly108 to His110) within a unique β-bridge stabilized by a hydrogen bond between Ser105-NH and His110-CO, while the other forms a β-turn without the H-bond. The H-bond (H-type) and H-bond free (F-type) configurations are also seen in some wild-type and mutant human SOD1s in the Protein Data Bank suggesting that they are interconvertible and an intrinsic property of SOD1s. The two structures serve as a basis for classification of these proteins and hopefully a guide to their stability and role in pathophysiology.
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Munier-Lehmann H, Vidalain PO, Tangy F, Janin YL. On dihydroorotate dehydrogenases and their inhibitors and uses. J Med Chem 2013; 56:3148-67. [PMID: 23452331 DOI: 10.1021/jm301848w] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Proper nucleosides availability is crucial for the proliferation of living entities (eukaryotic cells, parasites, bacteria, and virus). Accordingly, the uses of inhibitors of the de novo nucleosides biosynthetic pathways have been investigated in the past. In the following we have focused on dihydroorotate dehydrogenase (DHODH), the fourth enzyme in the de novo pyrimidine nucleosides biosynthetic pathway. We first described the different types of enzyme in terms of sequence, structure, and biochemistry, including the reported bioassays. In a second part, the series of inhibitors of this enzyme along with a description of their potential or actual uses were reviewed. These inhibitors are indeed used in medicine to treat autoimmune diseases such as rheumatoid arthritis or multiple sclerosis (leflunomide and teriflunomide) and have been investigated in treatments of cancer, virus, and parasite infections (i.e., malaria) as well as in crop science.
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Affiliation(s)
- Hélène Munier-Lehmann
- Institut Pasteur, Unité de Chimie et Biocatalyse, Département de Biologie Structurale et Chimie, 28 Rue du Dr. Roux, 75724 Paris Cedex 15, France
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13
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Truong L, Hevener KE, Rice AJ, Patel K, Johnson ME, Lee H. High-level expression, purification, and characterization of Staphylococcus aureus dihydroorotase (PyrC) as a cleavable His-SUMO fusion. Protein Expr Purif 2012; 88:98-106. [PMID: 23246866 DOI: 10.1016/j.pep.2012.11.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 11/21/2012] [Accepted: 11/29/2012] [Indexed: 01/29/2023]
Abstract
Staphylococcus aureus is a pathogenic bacterium that causes a variety of mild to lethal human diseases. The rapid spread of multidrug-resistant strains makes the discovery of new antimicrobial agents critical. Dihydroorotase (PyrC), the third enzyme in the bacterial pyrimidine biosynthesis pathway, is structurally and mechanistically distinct from its mammalian counterpart. It has been confirmed to be essential in S. aureus making it an attractive antibacterial drug target. No protocol to express and purify S. aureus PyrC (SaPyrC) has been reported. To obtain the SaPyrC enzyme and overcome anticipated solubility problems, the SaPyrC gene was cloned into the pET-SUMO vector. The N-terminal His-SUMO fused SaPyrC was expressed in Escherichia coli BL21 (DE3) with an HRV 3C protease recognition site inserted between the SUMO tag and SaPyrC to allow for improved cleavage by HRV protease. Purification of cleaved protein using HisTrap affinity and gel filtration columns resulted in native SaPyrC with estimated 95% purity and 40% yield. Both His-SUMO tagged and native SaPyrC form dimers, and enzyme characterization studies have shown that the His-SUMO tag affects enzyme activity slightly. Forward and reverse kinetic rate constants for both tagged and native SaPyrC were determined, and pH profiling studies revealed the optimal pH values for forward and reverse reactions.
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Affiliation(s)
- Lena Truong
- Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, 900 S. Ashland Ave., Suite 3100, Chicago, IL 60607-7173, USA
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