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Song H, Wang B, Zhao G, Lu S, Zhang D, Kong J, Li J, Zhang X, Lyu Y, Liu L. Discovery and biochemical characterization of two hexokinases from Crassostrea gigas. Protein Expr Purif 2024; 215:106408. [PMID: 38008389 DOI: 10.1016/j.pep.2023.106408] [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: 10/18/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/28/2023]
Abstract
Hexokinases (HKs) play a vital role in glucose metabolism, which controls the first committed step catalyzing the production of glucose-6-phosphate from glucose. Two HKs (CGIHK1 and CGIHK2) from the Pacific oyster Crassostrea giga were cloned and characterized. CGIHK1 and CGIHK2 were recombinantly expressed in Escherichia coli and successfully purified by the Ni-NTA column. The optimum pH of the two enzymes was pH 8.0 and 8.5, respectively. The optimum temperature of the two enzymes was 42 °C and 50 °C, respectively. Both enzymes showed a clear requirement for divalent magnesium and were strongly inhibited by SDS. CGIHK1 exhibited highly strict substrate specificity to glucose, while CGIHK2 could also catalyze other 11 monosaccharide substrates. This is the first report on the in vitro biosynthesis of glucose-6-phosphate by the hexokinases from Crassostrea gigas. The facile expression and purification procedures combined with different substrate specificities make CGIHK1 and CGIHK2 candidates for the biosynthesis of glucose-6-phosphate and other sugar-phosphates.
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Affiliation(s)
- Huibo Song
- College of Agricultural and Biological Engineering (College of Tree Peony), Heze University, Heze, 274015, China; Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Bo Wang
- College of Agricultural and Biological Engineering (College of Tree Peony), Heze University, Heze, 274015, China
| | - Guihong Zhao
- College of Agricultural and Biological Engineering (College of Tree Peony), Heze University, Heze, 274015, China.
| | - Shihai Lu
- Shandong Bigtree Dreyfus Special Meals Food Co., Ltd, Heze, 274000, China
| | - Dahu Zhang
- Shandong Bigtree Dreyfus Special Meals Food Co., Ltd, Heze, 274000, China
| | - Jianbiao Kong
- Heze Product Inspection and Testing Research Institute, Heze, 274000, China
| | - Jianxin Li
- Heze Institute for Food and Drug Control. Heze, 274000, China
| | - Xiaoyang Zhang
- School of Marine and Bioengineering, Yancheng Institute of Technology, Yancheng, 224051, China
| | - Yongmei Lyu
- School of Marine and Bioengineering, Yancheng Institute of Technology, Yancheng, 224051, China
| | - Li Liu
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.
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2
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Dillenberger M, Werner AD, Velten AS, Rahlfs S, Becker K, Fritz-Wolf K. Structural Analysis of Plasmodium falciparum Hexokinase Provides Novel Information about Catalysis Due to a Plasmodium-Specific Insertion. Int J Mol Sci 2023; 24:12739. [PMID: 37628920 PMCID: PMC10454665 DOI: 10.3390/ijms241612739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/10/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
The protozoan parasite Plasmodium falciparum is the causative pathogen of the most severe form of malaria, for which novel strategies for treatment are urgently required. The primary energy supply for intraerythrocytic stages of Plasmodium is the production of ATP via glycolysis. Due to the parasite's strong dependence on this pathway and the significant structural differences of its glycolytic enzymes compared to its human counterpart, glycolysis is considered a potential drug target. In this study, we provide the first three-dimensional protein structure of P. falciparum hexokinase (PfHK) containing novel information about the mechanisms of PfHK. We identified for the first time a Plasmodium-specific insertion that lines the active site. Moreover, we propose that this insertion plays a role in ATP binding. Residues of the insertion further seem to affect the tetrameric interface and therefore suggest a special way of communication among the different monomers. In addition, we confirmed that PfHK is targeted and affected by oxidative posttranslational modifications (oxPTMs). Both S-glutathionylation and S-nitrosation revealed an inhibitory effect on the enzymatic activity of PfHK.
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Affiliation(s)
- Melissa Dillenberger
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany; (M.D.)
| | - Anke-Dorothee Werner
- Institute of Virology, University of Marburg, Hans-Meerwein-Str. 2, D-35043 Marburg, Germany
| | - Ann-Sophie Velten
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany; (M.D.)
| | - Stefan Rahlfs
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany; (M.D.)
| | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany; (M.D.)
| | - Karin Fritz-Wolf
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany; (M.D.)
- Max-Planck Institute for Medical Research, Jahnstr. 29, D-69120 Heidelberg, Germany
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3
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dos Santos DA, Souza HFS, Silber AM, de Souza TDACB, Ávila AR. Protein kinases on carbon metabolism: potential targets for alternative chemotherapies against toxoplasmosis. Front Cell Infect Microbiol 2023; 13:1175409. [PMID: 37287468 PMCID: PMC10242022 DOI: 10.3389/fcimb.2023.1175409] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023] Open
Abstract
The apicomplexan parasite Toxoplasma gondii is the causative agent of toxoplasmosis, a global disease that significantly impacts human health. The clinical manifestations are mainly observed in immunocompromised patients, including ocular damage and neuronal alterations leading to psychiatric disorders. The congenital infection leads to miscarriage or severe alterations in the development of newborns. The conventional treatment is limited to the acute phase of illness, without effects in latent parasites; consequently, a cure is not available yet. Furthermore, considerable toxic effects and long-term therapy contribute to high treatment abandonment rates. The investigation of exclusive parasite pathways would provide new drug targets for more effective therapies, eliminating or reducing the side effects of conventional pharmacological approaches. Protein kinases (PKs) have emerged as promising targets for developing specific inhibitors with high selectivity and efficiency against diseases. Studies in T. gondii have indicated the presence of exclusive PKs without homologs in human cells, which could become important targets for developing new drugs. Knockout of specific kinases linked to energy metabolism have shown to impair the parasite development, reinforcing the essentiality of these enzymes in parasite metabolism. In addition, the specificities found in the PKs that regulate the energy metabolism in this parasite could bring new perspectives for safer and more efficient therapies for treating toxoplasmosis. Therefore, this review provides an overview of the limitations for reaching an efficient treatment and explores the role of PKs in regulating carbon metabolism in Toxoplasma, discussing their potential as targets for more applied and efficient pharmacological approaches.
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Affiliation(s)
| | - Higo Fernando Santos Souza
- Laboratory of Biochemistry of Trypanosomes (LabTryp), Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Ariel M. Silber
- Laboratory of Biochemistry of Trypanosomes (LabTryp), Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | | | - Andréa Rodrigues Ávila
- Laboratório de Pesquisa em Apicomplexa, Instituto Carlos Chagas, Fiocruz, Curitiba, Brazil
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4
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Silvestre A, Shintre SS, Rachidi N. Released Parasite-Derived Kinases as Novel Targets for Antiparasitic Therapies. Front Cell Infect Microbiol 2022; 12:825458. [PMID: 35252034 PMCID: PMC8893276 DOI: 10.3389/fcimb.2022.825458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/25/2022] [Indexed: 11/13/2022] Open
Abstract
The efficient manipulation of their host cell is an essential feature of intracellular parasites. Most molecular mechanisms governing the subversion of host cell by protozoan parasites involve the release of parasite-derived molecules into the host cell cytoplasm and direct interaction with host proteins. Among these released proteins, kinases are particularly important as they govern the subversion of important host pathways, such as signalling or metabolic pathways. These enzymes, which catalyse the transfer of a phosphate group from ATP onto serine, threonine, tyrosine or histidine residues to covalently modify proteins, are involved in numerous essential biological processes such as cell cycle or transport. Although little is known about the role of most of the released parasite-derived kinases in the host cell, they are examples of kinases hijacking host cellular pathways such as signal transduction or apoptosis, which are essential for immune response evasion as well as parasite survival and development. Here we present the current knowledge on released protozoan kinases and their involvement in host-pathogen interactions. We also highlight the knowledge gaps remaining before considering those kinases - involved in host signalling subversion - as antiparasitic drug targets.
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Affiliation(s)
- Anne Silvestre
- INRAE, Université de Tours, ISP, Nouzilly, France
- *Correspondence: Anne Silvestre, ; Najma Rachidi,
| | - Sharvani Shrinivas Shintre
- INRAE, Université de Tours, ISP, Nouzilly, France
- Institut Pasteur, Université de Paris and INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
| | - Najma Rachidi
- Institut Pasteur, Université de Paris and INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Paris, France
- *Correspondence: Anne Silvestre, ; Najma Rachidi,
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5
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Dolgikh VV, Tsarev AA, Timofeev SA, Zhuravlyov VS. Heterologous overexpression of active hexokinases from microsporidia Nosema bombycis and Nosema ceranae confirms their ability to phosphorylate host glucose. Parasitol Res 2019; 118:1511-1518. [DOI: 10.1007/s00436-019-06279-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/27/2019] [Indexed: 01/10/2023]
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Gas-Pascual E, Ichikawa HT, Sheikh MO, Serji MI, Deng B, Mandalasi M, Bandini G, Samuelson J, Wells L, West CM. CRISPR/Cas9 and glycomics tools for Toxoplasma glycobiology. J Biol Chem 2018; 294:1104-1125. [PMID: 30463938 DOI: 10.1074/jbc.ra118.006072] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/12/2018] [Indexed: 01/25/2023] Open
Abstract
Infection with the protozoan parasite Toxoplasma gondii is a major health risk owing to birth defects, its chronic nature, ability to reactivate to cause blindness and encephalitis, and high prevalence in human populations. Unlike most eukaryotes, Toxoplasma propagates in intracellular parasitophorous vacuoles, but like nearly all other eukaryotes, Toxoplasma glycosylates many cellular proteins and lipids and assembles polysaccharides. Toxoplasma glycans resemble those of other eukaryotes, but species-specific variations have prohibited deeper investigations into their roles in parasite biology and virulence. The Toxoplasma genome encodes a suite of likely glycogenes expected to assemble N-glycans, O-glycans, a C-glycan, GPI-anchors, and polysaccharides, along with their precursors and membrane transporters. To investigate the roles of specific glycans in Toxoplasma, here we coupled genetic and glycomics approaches to map the connections between 67 glycogenes, their enzyme products, the glycans to which they contribute, and cellular functions. We applied a double-CRISPR/Cas9 strategy, in which two guide RNAs promote replacement of a candidate gene with a resistance gene; adapted MS-based glycomics workflows to test for effects on glycan formation; and infected fibroblast monolayers to assess cellular effects. By editing 17 glycogenes, we discovered novel Glc0-2-Man6-GlcNAc2-type N-glycans, a novel HexNAc-GalNAc-mucin-type O-glycan, and Tn-antigen; identified the glycosyltransferases for assembling novel nuclear O-Fuc-type and cell surface Glc-Fuc-type O-glycans; and showed that they are important for in vitro growth. The guide sequences, editing constructs, and mutant strains are freely available to researchers to investigate the roles of glycans in their favorite biological processes.
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Affiliation(s)
- Elisabet Gas-Pascual
- Department of Biochemistry and Molecular Biology, Athens, Georgia 30602; Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602
| | | | | | | | - Bowen Deng
- Department of Biochemistry and Molecular Biology, Athens, Georgia 30602; Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602
| | - Msano Mandalasi
- Department of Biochemistry and Molecular Biology, Athens, Georgia 30602; Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602
| | - Giulia Bandini
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts 02118
| | - John Samuelson
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts 02118
| | - Lance Wells
- Department of Biochemistry and Molecular Biology, Athens, Georgia 30602; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Christopher M West
- Department of Biochemistry and Molecular Biology, Athens, Georgia 30602; Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602.
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7
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Sun M, Liao S, Zhang L, Wu C, Qi N, Lv M, Li J, Lin X, Zhang J, Xie M, Zhu G, Cai J. Molecular and biochemical characterization of Eimeria tenella hexokinase. Parasitol Res 2016; 115:3425-33. [DOI: 10.1007/s00436-016-5104-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 04/28/2016] [Indexed: 12/20/2022]
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Advanced enzymology, expression profile and immune response of Clonorchis sinensis hexokinase show its application potential for prevention and control of clonorchiasis. PLoS Negl Trop Dis 2015; 9:e0003641. [PMID: 25799453 PMCID: PMC4370448 DOI: 10.1371/journal.pntd.0003641] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 02/24/2015] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Approximately 35 million people are infected with Clonorchis sinensis (C. sinensis) globally, of whom 15 million are in China. Glycolytic enzymes are recognized as crucial molecules for trematode survival and have been targeted for vaccine and drug development. Hexokinase of C. sinensis (CsHK), as the first key regulatory enzyme of the glycolytic pathway, was investigated in the current study. PRINCIPAL FINDINGS There were differences in spatial structure and affinities for hexoses and phosphate donors between CsHK and HKs from humans or rats, the definitive hosts of C. sinensis. Effectors (AMP, PEP, and citrate) and a small molecular inhibitor regulated the enzymatic activity of rCsHK, and various allosteric systems were detected. CsHK was distributed in the worm extensively as well as in liver tissue and serum from C. sinensis infected rats. Furthermore, high-level specific IgG1 and IgG2a were induced in rats by immunization with rCsHK. The enzymatic activity of CsHK was suppressed by the antibody in vitro. Additionally, the survival of C. sinensis was inhibited by the antibody in vivo and in vitro. CONCLUSIONS/SIGNIFICANCE Due to differences in putative spatial structure and enzymology between CsHK and HK from the host, its extensive distribution in adult worms, and its expression profile as a component of excretory/secretory products, together with its good immunogenicity and immunoreactivity, as a key glycolytic enzyme, CsHK shows potential as a vaccine and as a promising drug target for Clonorchiasis.
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9
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Sequence analysis and molecular characterization of Clonorchis sinensis hexokinase, an unusual trimeric 50-kDa glucose-6-phosphate-sensitive allosteric enzyme. PLoS One 2014; 9:e107940. [PMID: 25232723 PMCID: PMC4169440 DOI: 10.1371/journal.pone.0107940] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/15/2014] [Indexed: 12/17/2022] Open
Abstract
Clonorchiasis, which is induced by the infection of Clonorchis sinensis (C. sinensis), is highly associated with cholangiocarcinoma. Because the available examination, treatment and interrupting transmission provide limited opportunities to prevent infection, it is urgent to develop integrated strategies to prevent and control clonorchiasis. Glycolytic enzymes are crucial molecules for trematode survival and have been targeted for drug development. Hexokinase of C. sinensis (CsHK), the first key regulatory enzyme of the glycolytic pathway, was characterized in this study. The calculated molecular mass (Mr) of CsHK was 50.0 kDa. The obtained recombinant CsHK (rCsHK) was a homotrimer with an Mr of approximately 164 kDa, as determined using native PAGE and gel filtration. The highest activity was obtained with 50 mM glycine-NaOH at pH 10 and 100 mM Tris-HCl at pH 8.5 and 10. The kinetics of rCsHK has a moderate thermal stability. Compared to that of the corresponding negative control, the enzymatic activity was significantly inhibited by praziquantel (PZQ) and anti-rCsHK serum. rCsHK was homotropically and allosterically activated by its substrates, including glucose, mannose, fructose, and ATP. ADP exhibited mixed allosteric effect on rCsHK with respect to ATP, while inorganic pyrophosphate (PPi) displayed net allosteric activation with various allosteric systems. Fructose behaved as a dose-dependent V activator with the substrate glucose. Glucose-6-phosphate (G6P) displayed net allosteric inhibition on rCsHK with respect to ATP or glucose with various allosteric systems in a dose-independent manner. There were differences in both mRNA and protein levels of CsHK among the life stages of adult worm, metacercaria, excysted metacercaria and egg of C. sinensis, suggesting different energy requirements during different development stages. Our study furthers the understanding of the biological functions of CsHK and supports the need to screen for small molecule inhibitors of CsHK to interfere with glycolysis in C. sinensis.
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10
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A unique hexokinase in Cryptosporidium parvum, an apicomplexan pathogen lacking the Krebs cycle and oxidative phosphorylation. Protist 2014; 165:701-14. [PMID: 25216472 DOI: 10.1016/j.protis.2014.08.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 08/10/2014] [Accepted: 08/13/2014] [Indexed: 01/25/2023]
Abstract
Cryptosporidium parvum may cause virtually untreatable infections in AIDS patients, and is recently identified as one of the top four diarrheal pathogens in children in developing countries. Cryptosporidium differs from other apicomplexans (e.g., Plasmodium and Toxoplasma) by lacking many metabolic pathways including the Krebs cycle and cytochrome-based respiratory chain, thus relying mainly on glycolysis for ATP production. Here we report the molecular and biochemical characterizations of a hexokinase in C. parvum (CpHK). Our phylogenetic reconstructions indicated that apicomplexan hexokinases including CpHK were highly divergent from those of humans and animals (i.e., at the base of the eukaryotic clade). CpHK displays unique kinetic features that differ from those in mammals and Toxoplasma gondii (TgHK) in the preference towards various hexoses and its capacity to use ATP and other NTPs. CpHK also displays substrate inhibition by ATP. Moreover, 2-deoxy-D-glucose (2DG) could not only inhibit the CpHK activity, but also the parasite growth in vitro at concentrations nontoxic to host cells (IC(50) = 0.54 mM). While the exact action of 2-deoxy-D-glucose on the parasite is subject to further verification, our data suggest that CpHK and the glycolytic pathway may be explored for developing anti-cryptosporidial therapeutics.
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Zhou DH, Zhao FR, Nisbet AJ, Xu MJ, Song HQ, Lin RQ, Huang SY, Zhu XQ. Comparative proteomic analysis of differentToxoplasma gondiigenotypes by two-dimensional fluorescence difference gel electrophoresis combined with mass spectrometry. Electrophoresis 2013; 35:533-45. [DOI: 10.1002/elps.201300044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 08/30/2013] [Accepted: 10/10/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Dong-Hui Zhou
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Fu-Rong Zhao
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Alasdair J. Nisbet
- Vaccines and Diagnostics, Moredun Research Institute; Pentlands Science Park; Scotland UK
| | - Min-Jun Xu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Hui-Qun Song
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Rui-Qing Lin
- College of Veterinary Medicine; South China Agricultural University; Guangzhou Guangdong Province P. R. China
| | - Si-Yang Huang
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology; Key Laboratory of Veterinary Parasitology of Gansu Province; Lanzhou Veterinary Research Institute; Chinese Academy of Agricultural Sciences; Lanzhou Gansu Province P. R. China
- College of Animal Science and Veterinary Medicine; Heilongjiang Bayi Agricultural University; Daqing Heilongjiang Province P. R. China
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Tjhin ET, Staines HM, van Schalkwyk DA, Krishna S, Saliba KJ. Studies with the Plasmodium falciparum hexokinase reveal that PfHT limits the rate of glucose entry into glycolysis. FEBS Lett 2013; 587:3182-7. [PMID: 23954294 DOI: 10.1016/j.febslet.2013.07.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/25/2013] [Accepted: 07/31/2013] [Indexed: 12/16/2022]
Abstract
To characterise plasmodial glycolysis, we generated two transgenic Plasmodium falciparum lines, one expressing P. falciparum hexokinase (PfHK) tagged with GFP (3D7-PfHK(GFP)) and another overexpressing native PfHK (3D7-PfHK(+)). Contrary to previous reports, we propose that PfHK is cytosolic. The glucose analogue, 2-deoxy-d-glucose (2-DG) was nearly 2-fold less toxic to 3D7-PfHK(+) compared with control parasites, supporting PfHK as a potential drug target. Although PfHK activity was higher in 3D7-PfHK(+), they accumulated phospho-[(14)C]2-DG at the same rate as control parasites. Transgenic parasites overexpressing the parasite's glucose transporter (PfHT) accumulated phospho-[(14)C]2-DG at a higher rate, consistent with glucose transport limiting glucose entry into glycolysis.
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Affiliation(s)
- Erick T Tjhin
- Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT 0200, Australia
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13
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Interrogating a hexokinase-selected small-molecule library for inhibitors of Plasmodium falciparum hexokinase. Antimicrob Agents Chemother 2013; 57:3731-7. [PMID: 23716053 DOI: 10.1128/aac.00662-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parasites in the genus Plasmodium cause disease throughout the tropic and subtropical regions of the world. P. falciparum, one of the deadliest species of the parasite, relies on glycolysis for the generation of ATP while it inhabits the mammalian red blood cell. The first step in glycolysis is catalyzed by hexokinase (HK). While the 55.3-kDa P. falciparum HK (PfHK) shares several biochemical characteristics with mammalian HKs, including being inhibited by its products, it has limited amino acid identity (~26%) to the human HKs, suggesting that enzyme-specific therapeutics could be generated. To that end, interrogation of a selected small-molecule library of HK inhibitors has identified a class of PfHK inhibitors, isobenzothiazolinones, some of which have 50% inhibitory concentrations (IC50s) of <1 μM. Inhibition was reversible by dilution but not by treatment with a reducing agent, suggesting that the basis for enzyme inactivation was not covalent association with the inhibitor. Lastly, six of these compounds and the related molecule ebselen inhibited P. falciparum growth in vitro (50% effective concentration [EC50] of ≥ 0.6 and <6.8 μM). These findings suggest that the chemotypes identified here could represent leads for future development of therapeutics against P. falciparum.
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14
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Pace DA, Fang J, Cintron R, Docampo MD, Moreno SNJ. Overexpression of a cytosolic pyrophosphatase (TgPPase) reveals a regulatory role of PP(i) in glycolysis for Toxoplasma gondii. Biochem J 2011; 440:229-40. [PMID: 21831041 PMCID: PMC4874478 DOI: 10.1042/bj20110641] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PP(i) is a critical element of cellular metabolism as both an energy donor and as an allosteric regulator of several metabolic pathways. The apicomplexan parasite Toxoplasma gondii uses PP(i) in place of ATP as an energy donor in at least two reactions: the glycolytic PP(i)-dependent PFK (phosphofructokinase) and V-H(+)-PPase [vacuolar H(+)-translocating PPase (pyrophosphatase)]. In the present study, we report the cloning, expression and characterization of cytosolic TgPPase (T. gondii soluble PPase). Amino acid sequence alignment and phylogenetic analysis indicates that the gene encodes a family I soluble PPase. Overexpression of the enzyme in extracellular tachyzoites led to a 6-fold decrease in the cytosolic concentration of PP(i) relative to wild-type strain RH tachyzoites. Unexpectedly, this subsequent reduction in PP(i) was associated with a higher glycolytic flux in the overexpressing mutants, as evidenced by higher rates of proton and lactate extrusion. In addition to elevated glycolytic flux, TgPPase-overexpressing tachyzoites also possessed higher ATP concentrations relative to wild-type RH parasites. These results implicate PP(i) as having a significant regulatory role in glycolysis and, potentially, other downstream processes that regulate growth and cell division.
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Affiliation(s)
- Douglas A Pace
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
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15
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Plata G, Hsiao TL, Olszewski KL, Llinás M, Vitkup D. Reconstruction and flux-balance analysis of the Plasmodium falciparum metabolic network. Mol Syst Biol 2010; 6:408. [PMID: 20823846 PMCID: PMC2964117 DOI: 10.1038/msb.2010.60] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 07/09/2010] [Indexed: 12/18/2022] Open
Abstract
Genome-scale metabolic reconstructions can serve as important tools for hypothesis generation and high-throughput data integration. Here, we present a metabolic network reconstruction and flux-balance analysis (FBA) of Plasmodium falciparum, the primary agent of malaria. The compartmentalized metabolic network accounts for 1001 reactions and 616 metabolites. Enzyme-gene associations were established for 366 genes and 75% of all enzymatic reactions. Compared with other microbes, the P. falciparum metabolic network contains a relatively high number of essential genes, suggesting little redundancy of the parasite metabolism. The model was able to reproduce phenotypes of experimental gene knockout and drug inhibition assays with up to 90% accuracy. Moreover, using constraints based on gene-expression data, the model was able to predict the direction of concentration changes for external metabolites with 70% accuracy. Using FBA of the reconstructed network, we identified 40 enzymatic drug targets (i.e. in silico essential genes), with no or very low sequence identity to human proteins. To demonstrate that the model can be used to make clinically relevant predictions, we experimentally tested one of the identified drug targets, nicotinate mononucleotide adenylyltransferase, using a recently discovered small-molecule inhibitor.
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Affiliation(s)
- Germán Plata
- Center for Computational Biology and Bioinformatics, Columbia University, New York City, NY 10032, USA
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Imada M, Kawashima S, Kanehisa M, Takeuchi T, Asai T. Characterization of alpha-phosphoglucomutase isozymes from Toxoplasma gondii. Parasitol Int 2010; 59:206-10. [PMID: 20153838 DOI: 10.1016/j.parint.2010.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 12/04/2009] [Accepted: 01/31/2010] [Indexed: 11/16/2022]
Abstract
The Toxoplasma gondii genome project has revealed two putative isoforms (TgPGM-I and TgPGM-II) of alpha-phosphoglucomutase (EC 5.4.2.2). We obtained recombinant proteins of these isoforms from the Beverley strain of T. gondii and characterized their properties, particularly the kinetic properties of these isoforms. The specific activities of TgPGM-I and TgPGM-II for alpha-D-glucose 1-phosphate were 338+/-9 and 84+/-6micromol/min/mg protein, respectively, at 37 degrees C under optimal conditions. The Kcat and Km values of TgPGM-I were 398+/-11/s and 0.19+/-0.03mM and those for TgPGM-II were 93+/-7/s and 3.53+/-0.91mM, respectively, for alpha-d-glucose 1-phosphate. Magnesium ions were the most effective divalent cations for both the enzyme activities. The maximum activities of both the enzymes were obtained in the presence of more than 0.2mM alpha-D-glucose 1,6-bisphosphate. Although both enzymes were attached to the alpha-phosphohexomutase superfamily, amino acid sequence homology between TgPGM-I and TgPGM-II showed very low overall identity (25%). No alpha-phosphomannomutase (EC 5.4.2.8) activity was detected for either enzyme. The data indicated that TgPGM-I, but not TgPGM-II, may play an important role in alpha-D-glucose 6-phosphate production.
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Affiliation(s)
- Mihoko Imada
- Department of Tropical Medicine and Parasitology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
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Saito T, Nishi M, Lim MI, Wu B, Maeda T, Hashimoto H, Takeuchi T, Roos DS, Asai T. A novel GDP-dependent pyruvate kinase isozyme from Toxoplasma gondii localizes to both the apicoplast and the mitochondrion. J Biol Chem 2008; 283:14041-52. [PMID: 18326043 DOI: 10.1074/jbc.m709015200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We previously reported a cytosolic pyruvate kinase (EC 2.7.1.40) from Toxoplasma gondii (TgPyKI) that differs from most eukaryotic pyruvate kinases in being regulated by glucose 6-phosphate rather than fructose 1,6-diphosphate. Another putative pyruvate kinase (TgPyKII) was identified from parasite genome, which exhibits 32% amino acid sequence identity to TgPyKI and retains pyruvate kinase signature motifs and amino acids essential for substrate binding and catalysis. Whereas TgPyKI is most closely related to plant/algal enzymes, phylogenetic analysis suggests a proteobacterial origin for TgPyKII. Enzymatic characterization of recombinant TgPyKII shows a high pH optimum at 8.5, and a preference for GDP as a phosphate recipient. Catalytic activity is independent of K+, and no allosteric or regulatory effects were observed in the presence of fructose 1,6-diphosphate, fructose 2,6-diphosphate, glucose 6-phosphate, ribose 5-phosphate, AMP, or ATP. Unlike TgPyKI, native TgPyKII activity was exclusively associated with the membranous fraction of a T. gondii tachyzoite lysate. TgPyKII possesses a long N-terminal extension containing five putative start codons before the conserved region and localizes to both apicoplast and mitochondrion by immunofluorescence assay using native antibody and fluorescent protein fusion to the N-terminal extension. Further deletional and site-directed mutagenesis suggests that a translation product from 1st Met is responsible for the localization to the apicoplast, whereas one from 3rd Met is for the mitochondrion. This is the first study of a potential mitochondrial pyruvate kinase in any system.
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Affiliation(s)
- Tomoya Saito
- Department of Tropical Medicine and Parasitology, Keio University School of Medicine, 35 Shinanomachi, Tokyo 160-8582, Japan.
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Chan M, Tan DSH, Sim TS. Plasmodium falciparum pyruvate kinase as a novel target for antimalarial drug-screening. Travel Med Infect Dis 2006; 5:125-31. [PMID: 17298920 DOI: 10.1016/j.tmaid.2006.01.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/16/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND Global travellers are increasingly at risk of contracting malaria. The increasing occurrence of drug-resistance in many endemic areas emphasizes the need for novel drug targets for antimalarial-screening. In this study, the use of pyruvate kinase as a drug-target is evaluated. The functional validation of a gene encoding pyruvate kinase (designated PK1) has previously been reported. However, alternative copies of this enzyme encoded by Plasmodium falciparum could also circumvent the role of PK1. A survey of genome data revealed a putative ORF seemingly coding for another pyruvate kinase (designated PK2). METHODS The expression of PK1 and PK2 in in vitro cultures were investigated by RT-PCR. Biocomputational analysis was carried out to identify structural differences between the P. falciparum pyruvate kinases and the corresponding enzymes from its human host. RESULTS Both PK1 and PK2 were indeed actively transcribed during the intraerythrocytic stages, suggesting the involvement of both enzymes during infection. A comparison of amino acid residues at the effector binding sites of PK1 and PK2, to those of the human pyruvate kinases revealed some significant differences that could serve as targets for selective inhibitors to be designed against parasitic pyruvate kinases. CONCLUSION Experimental evidence for the expression of both PK1 and PK2 during the blood stages of malaria infection was provided. Interestingly, phylogenetic analysis revealed that the "PK2" type of enzyme appears to be confined to Apicomplexans, an important observation with respect to the assessment of PK2 as a drug-target.
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Affiliation(s)
- Maurice Chan
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD4, 5 Science Drive 2, Singapore 117597, Singapore
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