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de Lorenzo L, Stack TMM, Fox KM, Walstrom KM. Catalytic mechanism and kinetics of malate dehydrogenase. Essays Biochem 2024; 68:73-82. [PMID: 38721782 PMCID: PMC11461317 DOI: 10.1042/ebc20230086] [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: 03/04/2024] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 10/04/2024]
Abstract
Malate dehydrogenase (MDH) is a ubiquitous and central enzyme in cellular metabolism, found in all kingdoms of life, where it plays vital roles in the cytoplasm and various organelles. It catalyzes the reversible NAD+-dependent reduction of L-malate to oxaloacetate. This review describes the reaction mechanism for MDH and the effects of mutations in and around the active site on catalytic activity and substrate specificity, with a particular focus on the loop that encloses the active site after the substrates have bound. While MDH exhibits selectivity for its preferred substrates, mutations can alter the specificity of MDH for each cosubstrate. The kinetic characteristics and similarities of a variety of MDH isozymes are summarized, and they illustrate that the KM values are consistent with the relative concentrations of the substrates in cells. As a result of its existence in different cellular environments, MDH properties vary, making it an attractive model enzyme for studying enzyme activity and structure under different conditions.
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Affiliation(s)
- Laura de Lorenzo
- Department of Biochemistry and Molecular Biology, University of New Mexico, School of Medicine, Albuquerque, NM, U.S.A
| | - Tyler M M Stack
- Department of Chemistry and Biochemistry, Providence College, Providence, RI, U.S.A
| | - Kristin M Fox
- Department of Chemistry, Union College, Schenectady, NY, U.S.A
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2
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Springer AL, Agrawal S, Chang EP. Malate dehydrogenase in parasitic protozoans: roles in metabolism and potential therapeutic applications. Essays Biochem 2024; 68:235-251. [PMID: 38938216 PMCID: PMC11461325 DOI: 10.1042/ebc20230075] [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: 03/06/2024] [Revised: 05/31/2024] [Accepted: 06/18/2024] [Indexed: 06/29/2024]
Abstract
The role of malate dehydrogenase (MDH) in the metabolism of various medically significant protozoan parasites is reviewed. MDH is an NADH-dependent oxidoreductase that catalyzes interconversion between oxaloacetate and malate, provides metabolic intermediates for both catabolic and anabolic pathways, and can contribute to NAD+/NADH balance in multiple cellular compartments. MDH is present in nearly all organisms; isoforms of MDH from apicomplexans (Plasmodium falciparum, Toxoplasma gondii, Cryptosporidium spp.), trypanosomatids (Trypanosoma brucei, T. cruzi) and anaerobic protozoans (Trichomonas vaginalis, Giardia duodenalis) are presented here. Many parasitic species have complex life cycles and depend on the environment of their hosts for carbon sources and other nutrients. Metabolic plasticity is crucial to parasite transition between host environments; thus, the regulation of metabolic processes is an important area to explore for therapeutic intervention. Common themes in protozoan parasite metabolism include emphasis on glycolytic catabolism, substrate-level phosphorylation, non-traditional uses of common pathways like tricarboxylic acid cycle and adapted or reduced mitochondria-like organelles. We describe the roles of MDH isoforms in these pathways, discuss unusual structural or functional features of these isoforms relevant to activity or drug targeting, and review current studies exploring the therapeutic potential of MDH and related genes. These studies show that MDH activity has important roles in many metabolic pathways, and thus in the metabolic transitions of protozoan parasites needed for success as pathogens.
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Affiliation(s)
- Amy L Springer
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, U.S.A
| | - Swati Agrawal
- Department of Biological Sciences, University of Mary Washington, Fredericksburg, VA, U.S.A
| | - Eric P Chang
- Department of Chemistry and Physical Sciences, Pace University, New York, NY, U.S.A
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3
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In search of suitable protein targets for anti-malarial and anti-dengue drug discovery. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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4
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Lactate dehydrogenase and malate dehydrogenase: Potential antiparasitic targets for drug development studies. Bioorg Med Chem 2021; 50:116458. [PMID: 34687983 DOI: 10.1016/j.bmc.2021.116458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 09/27/2021] [Accepted: 10/05/2021] [Indexed: 12/24/2022]
Abstract
Parasitic diseases remain a major public health concern for humans, claiming millions of lives annually. Although different treatments are required for these diseases, drug usage is limited due to the development of resistance and toxicity, which necessitate alternative therapies. It has been shown in the literature that parasitic lactate dehydrogenases (LDH) and malate dehydrogenases (MDH) have unique pharmacological selective and specificity properties compared to other isoforms, thus highlighting them as viable therapeutic targets involved in aerobic and anaerobic glycolytic pathways. LDH and MDH are important therapeutic targets for invasive parasites because they play a critical role in the progression and development of parasitic diseases. Any strategy to impede these enzymes would be fatal to the parasites, paving the way to develop and discover novel antiparasitic agents. This review aims to highlight the importance of parasitic LDH and MDH as therapeutic drug targets in selected obligate apicoplast parasites. To the best of our knowledge, this review presents the first comprehensive review of LDH and MDH as potential antiparasitic targets for drug development studies.
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5
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Reyes Romero A, Lunev S, Popowicz GM, Calderone V, Gentili M, Sattler M, Plewka J, Taube M, Kozak M, Holak TA, Dömling ASS, Groves MR. A fragment-based approach identifies an allosteric pocket that impacts malate dehydrogenase activity. Commun Biol 2021; 4:949. [PMID: 34376783 PMCID: PMC8355244 DOI: 10.1038/s42003-021-02442-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 07/09/2021] [Indexed: 11/14/2022] Open
Abstract
Malate dehydrogenases (MDHs) sustain tumor growth and carbon metabolism by pathogens including Plasmodium falciparum. However, clinical success of MDH inhibitors is absent, as current small molecule approaches targeting the active site are unselective. The presence of an allosteric binding site at oligomeric interface allows the development of more specific inhibitors. To this end we performed a differential NMR-based screening of 1500 fragments to identify fragments that bind at the oligomeric interface. Subsequent biophysical and biochemical experiments of an identified fragment indicate an allosteric mechanism of 4-(3,4-difluorophenyl) thiazol-2-amine (4DT) inhibition by impacting the formation of the active site loop, located >30 Å from the 4DT binding site. Further characterization of the more tractable homolog 4-phenylthiazol-2-amine (4PA) and 16 other derivatives are also reported. These data pave the way for downstream development of more selective molecules by utilizing the oligomeric interfaces showing higher species sequence divergence than the MDH active site. Romero et al. perform NMR-based screening of 1500 fragments to identify fragments that bind at the oligomeric interface of malate dehydrogenase (MDH). Their study indicates an allosteric mechanism impacting enzymatic activity, paving the way for development of more selective molecules and a starting point for the future development of specific MDH inhibitors.
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Affiliation(s)
- Atilio Reyes Romero
- Drug Design, University of Groningen, Department of Pharmacy, Groningen, The Netherlands
| | - Serjey Lunev
- EV Biotech, Zernikelaan 8, Groningen, the Netherlands
| | - Grzegorz M Popowicz
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Vito Calderone
- CERM and Department of Chemistry, University of Florence, Sesto Fiorentino, Italy.
| | | | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.,Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Jacek Plewka
- Faculty of Chemistry, Jagiellonian University, Krakow, Poland
| | - Michał Taube
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
| | - Maciej Kozak
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland.,National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Kraków, Poland
| | - Tad A Holak
- Faculty of Chemistry, Jagiellonian University, Krakow, Poland
| | - Alexander S S Dömling
- Drug Design, University of Groningen, Department of Pharmacy, Groningen, The Netherlands
| | - Matthew R Groves
- Drug Design, University of Groningen, Department of Pharmacy, Groningen, The Netherlands.
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6
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Jiang Z, Long L, Liang M, Li H, Chen Y, Zheng M, Ni H, Li Q, Zhu Y. Characterization of a glucose-stimulated β-glucosidase from Microbulbifer sp. ALW1. Microbiol Res 2021; 251:126840. [PMID: 34375805 DOI: 10.1016/j.micres.2021.126840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 05/18/2021] [Accepted: 08/02/2021] [Indexed: 11/27/2022]
Abstract
Glucose-tolerant and/or glucose-stimulated β-glucosidase is of great interest for its industrial utilization in enzymatic digestion of lignocellulosic biomass for biofuel production. In this study, a new gene of β-glucosidase MaGlu1A was cloned from an alginate-degrading marine bacterium Microbulbifer sp. ALW1. The gene of MaGlu1A encoded a 472-amino acid protein classified into the glycosyl hydrolase family 1 (GH1). The recombinant β-glucosidase was overexpressed and purified from Escherichia coli with a molecular mass of 65.0 kDa. Structure analysis illustrated the catalytic acid/base residue Glu186 and nucleophilic residue Glu370 in the enzyme. MaGlu1A displayed optimal activity at 40 °C and pH 4.5, respectively. It had substrate preference to the aryl-β-glycosidic bonds with glucose, fucose, and galactose moieties, in addition to cellobiose. MaGlu1A demonstrated strong stimulation to the supplemental glucose. Site-directed mutagenesis suggested an essential role of Asn242 in glucose stimulation. The enzymatic characterization of MaGlu1A provides general information about its catalytic properties facilitating its practical applications.
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Affiliation(s)
- Zedong Jiang
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China
| | - Liufei Long
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China
| | - Meifang Liang
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China
| | - Hebin Li
- Xiamen Medical College, Xiamen, 361008, China
| | - Yanhong Chen
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China
| | - Mingjing Zheng
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China
| | - Hui Ni
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China
| | - Qingbiao Li
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China
| | - Yanbing Zhu
- College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China; Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, China; Research Center of Food Biotechnology of Xiamen City, Xiamen, 361021, China.
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7
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Zhang D, Zhu X, Hu D, Wen Z, Zhang C, Wu M. Improvement in the catalytic performance of a phenylpyruvate reductase from Lactobacillus plantarum by site-directed and saturation mutagenesis based on the computer-aided design. 3 Biotech 2021; 11:69. [PMID: 33489686 DOI: 10.1007/s13205-020-02633-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/28/2020] [Indexed: 01/02/2023] Open
Abstract
To enhance the specific activity and catalytic efficiency (k cat/K m) of an NADH-dependent LpPPR, its directed modification was performed based on the computer-aided design using molecular docking simulation and multiple sequence alignment. Firstly, five single-site variants of an LpPPR-encoding gene (lpppr) were amplified and expressed in E. coli BL21 (DE3). The asymmetric reduction of 20 mM phenylpyruvic acid (PPA) was carried out using 50 mg/mL E. coli/lpppr R53Q or /lpppr A79V whole wet cells at 37 °C for 20 min, giving d-phenyllactic acid (PLA) with 41.1 or 44.3% yield, being 1.17- or 1.26-fold that by E. coli/lpppr. Secondly, double-site variants were obtained by saturation mutagenesis of Ala79 in LpPPRR53Q. Among all tested E. coli transformants, E. coli/lpppr R53Q/A79V exhibited the highest d-PLA yield of 85.3%. The specific activity and k cat/K m of the purified LpPPRR53Q/A79V increased to 67.5 U/mg and 169.8 mM-1 s-1, which were 3.0- and 13.2-fold those of LpPPR, respectively. Finally, the catalytic mechanism analysis of LpPPRR53Q/A79V by molecular docking simulation indicated that the replacement of Arg53 in LpPPR with Gln expanded its substrate-binding pocket, while that Ala79 with Val formed an additional π-sigma interaction with phenyl group of PPA. SUPPLEMENTARY MATERIAL The online version of this article (10.1007/s13205-020-02633-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dong Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 China
| | - Xiuxiu Zhu
- School of Pharmaceutical Science, Jiangnan University, Wuxi, 214122 China
| | - Die Hu
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122 China
| | - Zheng Wen
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 China
| | - Chen Zhang
- School of Pharmaceutical Science, Jiangnan University, Wuxi, 214122 China
| | - Minchen Wu
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122 China
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8
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Lunev S, Butzloff S, Romero AR, Linzke M, Batista FA, Meissner KA, Müller IB, Adawy A, Wrenger C, Groves MR. Oligomeric interfaces as a tool in drug discovery: Specific interference with activity of malate dehydrogenase of Plasmodium falciparum in vitro. PLoS One 2018; 13:e0195011. [PMID: 29694407 PMCID: PMC5919072 DOI: 10.1371/journal.pone.0195011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/28/2018] [Indexed: 01/29/2023] Open
Abstract
Malaria remains a major threat to human health, as strains resistant to current therapeutics are discovered. Efforts in finding new drug targets are hampered by the lack of sufficiently specific tools to provide target validation prior to initiating expensive drug discovery projects. Thus, new approaches that can rapidly enable drug target validation are of significant interest. In this manuscript we present the crystal structure of malate dehydrogenase from Plasmodium falciparum (PfMDH) at 2.4 Å resolution and structure-based mutagenic experiments interfering with the inter-oligomeric interactions of the enzyme. We report decreased thermal stability, significantly decreased specific activity and kinetic parameters of PfMDH mutants upon mutagenic disruption of either oligomeric interface. In contrast, stabilization of one of the interfaces resulted in increased thermal stability, increased substrate/cofactor affinity and hyperactivity of the enzyme towards malate production at sub-millimolar substrate concentrations. Furthermore, the presented data show that our designed PfMDH mutant could be used as specific inhibitor of the wild type PfMDH activity, as mutated PfMDH copies were shown to be able to self-incorporate into the native assembly upon introduction in vitro, yielding deactivated mutant:wild-type species. These data provide an insight into the role of oligomeric assembly in regulation of PfMDH activity and reveal that recombinant mutants could be used as probe tool for specific modification of the wild type PfMDH activity, thus offering the potential to validate its druggability in vivo without recourse to complex genetics or initial tool compounds. Such tool compounds often lack specificity between host or pathogen proteins (or are toxic in in vivo trials) and result in difficulties in assessing cause and effect-particularly in cases when the enzymes of interest possess close homologs within the human host. Furthermore, our oligomeric interference approach could be used in the future in order to assess druggability of other challenging human pathogen drug targets.
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Affiliation(s)
- Sergey Lunev
- Structural Biology Unit, XB20 Drug Design, Department of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Sabine Butzloff
- LG Müller, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Atilio R. Romero
- Structural Biology Unit, XB20 Drug Design, Department of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Marleen Linzke
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Saõ Paulo, Brazil
| | - Fernando A. Batista
- Structural Biology Unit, XB20 Drug Design, Department of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Kamila A. Meissner
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Saõ Paulo, Brazil
| | - Ingrid B. Müller
- LG Müller, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Alaa Adawy
- Structural Biology Unit, XB20 Drug Design, Department of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Carsten Wrenger
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Saõ Paulo, Brazil
- * E-mail: (MRG); (CW)
| | - Matthew R. Groves
- Structural Biology Unit, XB20 Drug Design, Department of Pharmacy, University of Groningen, Groningen, The Netherlands
- * E-mail: (MRG); (CW)
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9
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Gharib G, Rashid N, Bashir Q, Gardner QTAA, Akhtar M, Imanaka T. Pcal_1699, an extremely thermostable malate dehydrogenase from hyperthermophilic archaeon Pyrobaculum calidifontis. Extremophiles 2015; 20:57-67. [PMID: 26507956 DOI: 10.1007/s00792-015-0797-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/15/2015] [Indexed: 10/22/2022]
Abstract
Two malate dehydrogenase homologs, Pcal_0564 and Pcal_1699, have been found in the genome of Pyrobaculum calidifontis. The gene encoding Pcal_1699 consisted of 927 nucleotides corresponding to a polypeptide of 309 amino acids. To examine the properties of Pcal_1699, the structural gene was cloned, expressed in Escherichia coli and the purified gene product was characterized. Pcal_1699 was NADH specific enzyme exhibiting a high malate dehydrogenase activity (886 U/mg) at optimal pH (10) and temperature (90 °C). Unfolding studies suggested that urea could not induce complete unfolding and inactivation of Pcal_1699 even at a final concentration of 8 M; however, in the presence of 4 M guanidine hydrochloride enzyme structure was unfolded with complete loss of enzyme activity. Thermostability experiments revealed that Pcal_1699 is the most thermostable malate dehydrogenase, reported to date, retaining more than 90 % residual activity even after heating for 6 h in boiling water.
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Affiliation(s)
- Ghazaleh Gharib
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan
| | - Naeem Rashid
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan.
| | - Qamar Bashir
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan
| | - Qura-Tul Ann Afza Gardner
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan
| | - Muhammad Akhtar
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan.,School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, UK
| | - Tadayuki Imanaka
- The Research Organization of Science & Technology, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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10
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Enzymatic activity analysis and catalytic essential residues identification of Brucella abortus malate dehydrogenase. ScientificWorldJournal 2014; 2014:973751. [PMID: 24895685 PMCID: PMC4033508 DOI: 10.1155/2014/973751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/24/2014] [Accepted: 04/09/2014] [Indexed: 12/01/2022] Open
Abstract
Malate dehydrogenase (MDH) plays important metabolic roles in bacteria. In this study, the recombinant MDH protein (His-MDH) of Brucella abortus was purified and its ability to catalyze the conversion of oxaloacetate (OAA) to L-malate (hereon referred to as MDH activity) was analyzed. Michaelis Constant (Km) and Maximum Reaction Velocity (Vmax) of the reaction were determined to be 6.45 × 10−3 M and 0.87 mM L−1 min−1, respectively. In vitro studies showed that His-MDH exhibited maximal MDH activity in pH 6.0 reaction buffer at 40°C. The enzymatic activity was 100%, 60%, and 40% inhibited by Cu2+, Zn2+, and Pb2+, respectively. In addition, six amino acids in the MDH were mutated to investigate their roles in the enzymatic activity. The results showed that the substitutions of amino acids Arg 89, Asp 149, Arg 152, His 176, or Thr 231 almost abolished the activity of His-MDH. The present study will help to understand MDH's roles in B. abortus metabolism.
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11
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Wrenger C, Müller IB, Schifferdecker AJ, Jain R, Jordanova R, Groves MR. Specific inhibition of the aspartate aminotransferase of Plasmodium falciparum. J Mol Biol 2010; 405:956-71. [PMID: 21087616 DOI: 10.1016/j.jmb.2010.11.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/05/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
Abstract
Aspartate aminotransferases (AspATs; EC 2.6.1.1) catalyze the conversion of aspartate and α-ketoglutarate into oxaloacetate and glutamate and are key enzymes in the nitrogen metabolism of all organisms. Recent findings suggest that the plasmodial enzyme [Plasmodium falciparum aspartate aminotransferase (PfAspAT)] may also play a pivotal role in energy metabolism and in the de novo biosynthesis of pyrimidines. However, while PfAspAT is a potential drug target, the high homology between the active sites of currently available AspAT structures hinders the development of specific inhibitors of these enzymes. In this article, we report the X-ray structure of the PfAspAT homodimer at a resolution of 2.8 Å. While the overall fold is similar to the currently available structures of other AspATs, the structure presented shows a significant divergence in the conformation of the N-terminal residues. Deletion of these divergent PfAspAT N-terminal residues results in a loss of activity for the recombinant protein, and addition of a peptide containing these 13 N-terminal residues results in inhibition both in vitro and in a lysate isolated from cultured parasites, while the activity of human cytosolic AspAT is unaffected. The finding that the divergent N-terminal amino acids of PfAspAT play a role in catalytic activity indicates that specific inhibition of the enzyme may provide a lead for the development of novel compounds in the treatment of malaria. We also report on the localization of PfAspAT to the parasite cytosol and discuss the implications of the role of PfAspAT in the supply of malate to the parasite mitochondria.
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Affiliation(s)
- Carsten Wrenger
- Department of Biochemistry, Bernhard Nocht Institute for Tropical Medicine, Bernhard Nocht Strasse 74, D-20359 Hamburg, Germany
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