1
|
Hou N, Li S, Jiang N, Piao X, Ma Y, Liu S, Chen Q. Merozoite Proteins Discovered by qRT-PCR-Based Transcriptome Screening of Plasmodium falciparum. Front Cell Infect Microbiol 2021; 11:777955. [PMID: 34956931 PMCID: PMC8696357 DOI: 10.3389/fcimb.2021.777955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/24/2021] [Indexed: 11/13/2022] Open
Abstract
The development of malaria vaccines and medicines depends on the discovery of novel malaria protein targets, but the functions of more than 40% of P. falciparum genes remain unknown. Asexual parasites are the critical stage that leads to serious clinical symptoms and that can be modulated by malaria treatments and vaccines. To identify critical genes involved in the development of Plasmodium parasites within erythrocytes, the expression profile of more than 5,000 genes distributed across the 14 chromosomes of the PF3D7 strain during its six critical developmental stages (merozoite, early-ring, late-ring, early trophozoite, late-trophozoite, and middle-schizont) was evaluated. Hence, a qRT-PCR-based transcriptome of the erythrocytic developmental process of P. falciparum was revealed. Weighted gene coexpression network analyses revealed that a large number of genes are upregulated during the merozoite release process. Further gene ontology analysis revealed that a cluster of genes is associated with merozoite and may be apical complex components. Among these genes, 135 were comprised within chromosome 14, and 80% of them were previously unknown in functions. Western blot and immunofluorescence assays using newly developed corresponding antibodies showed that some of these newly discovered proteins are highly expressed in merozoites. Further invasion inhibition assays revealed that specific antibodies against several novel merozoite proteins can interfere with parasite invasion. Taken together, our study provides a developmental transcriptome of the asexual parasites of P. falciparum and identifies a group of previously unknown merozoite proteins that may play important roles in the process of merozoite invasion.
Collapse
Affiliation(s)
- Nan Hou
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Shanshan Li
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ning Jiang
- Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.,The Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, Shenyang, China
| | - Xianyu Piao
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yu Ma
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Shuai Liu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Qijun Chen
- Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China.,The Research Unit for Pathogenic Mechanisms of Zoonotic Parasites, Chinese Academy of Medical Sciences, Shenyang, China
| |
Collapse
|
2
|
Fly ash supported NiO as an efficient catalyst for the synthesis of xanthene and its molecular docking study against plasmodium glutathione reductase. RESEARCH ON CHEMICAL INTERMEDIATES 2018. [DOI: 10.1007/s11164-018-3567-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
3
|
White K, Kim MJ, Han C, Park HJ, Ding D, Boyd K, Walker L, Linser P, Meneses Z, Slade C, Hirst J, Santostefano K, Terada N, Miyakawa T, Tanokura M, Salvi R, Someya S. Loss of IDH2 Accelerates Age-related Hearing Loss in Male Mice. Sci Rep 2018; 8:5039. [PMID: 29567975 PMCID: PMC5864918 DOI: 10.1038/s41598-018-23436-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 03/13/2018] [Indexed: 11/29/2022] Open
Abstract
Isocitrate dehydrogenase (IDH) 2 participates in the TCA cycle and catalyzes the conversion of isocitrate to α-ketoglutarate and NADP+ to NADPH. In the mitochondria, IDH2 also plays a key role in protecting mitochondrial components from oxidative stress by supplying NADPH to both glutathione reductase (GSR) and thioredoxin reductase 2 (TXNRD2). Here, we report that loss of Idh2 accelerates age-related hearing loss, the most common form of hearing impairment, in male mice. This was accompanied by increased oxidative DNA damage, increased apoptotic cell death, and profound loss of spiral ganglion neurons and hair cells in the cochlea of 24-month-old Idh2−/− mice. In young male mice, loss of Idh2 resulted in decreased NADPH redox state and decreased activity of TXNRD2 in the mitochondria of the inner ear. In HEI-OC1 mouse inner ear cell lines, knockdown of Idh2 resulted in a decline in cell viability and mitochondrial oxygen consumption. This was accompanied by decreased NADPH redox state and decreased activity of TXNRD2 in the mitochondria of the HEI-OC1 cells. Therefore, IDH2 functions as the principal source of NADPH for the mitochondrial thioredoxin antioxidant defense and plays an essential role in protecting hair cells and neurons against oxidative stress in the cochlea of male mice.
Collapse
Affiliation(s)
- Karessa White
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Mi-Jung Kim
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Chul Han
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Hyo-Jin Park
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, New York, 14214, United States
| | - Kevin Boyd
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Logan Walker
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Paul Linser
- Whitney Laboratory, University of Florida, St Augustine, Florida, 32080, United States
| | - Zaimary Meneses
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Cole Slade
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Jonathan Hirst
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States
| | - Katherine Santostefano
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, 32610, United States
| | - Naohiro Terada
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, 32610, United States
| | - Takuya Miyakawa
- Department of Applied Biological Chemistry, University of Tokyo, Yayoi, Tokyo, 113, Japan
| | - Masaru Tanokura
- Department of Applied Biological Chemistry, University of Tokyo, Yayoi, Tokyo, 113, Japan
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, New York, 14214, United States
| | - Shinichi Someya
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, 32610, United States.
| |
Collapse
|
4
|
Sussmann RAC, Fotoran WL, Kimura EA, Katzin AM. Plasmodium falciparum uses vitamin E to avoid oxidative stress. Parasit Vectors 2017; 10:461. [PMID: 29017543 PMCID: PMC5634829 DOI: 10.1186/s13071-017-2402-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 09/25/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum is sensitive to oxidative stress in vitro and in vivo, and many drugs such as artemisinin, chloroquine and cercosporin interfere in the parasite's redox system. To minimize the damage caused by reactive radicals, antioxidant enzymes and their substrates found in parasites and in erythrocytes must be functionally active. It was shown that P. falciparum synthesizes vitamin E and that usnic acid acts as an inhibitor of its biosynthesis. Vitamin E is a potent antioxidant that protects polyunsaturated fatty acids from lipid peroxidation, and this activity can be measured by detecting its oxidized product and by evaluating reactive oxygen species (ROS) levels. RESULTS Here, we demonstrated that ROS levels increased in P. falciparum when vitamin E biosynthesis was inhibited by usnic acid treatment and decreased to basal levels if exogenous vitamin E was added. Furthermore, we used metabolic labelling to demonstrate that vitamin E biosynthesized by the parasite acts as an antioxidant since we could detect its radiolabeled oxidized product. The treatment with chloroquine or cercosporin of the parasites increased the ratio between α-tocopherolquinone and α-tocopherol. CONCLUSIONS Our findings demonstrate that vitamin E produced endogenously by P. falciparum is active as an antioxidant, probably protecting the parasite from the radicals generated by drugs.
Collapse
Affiliation(s)
- Rodrigo A C Sussmann
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Wesley L Fotoran
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Emilia A Kimura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Alejandro M Katzin
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
| |
Collapse
|
5
|
Siddiqui G, Srivastava A, Russell AS, Creek DJ. Multi-omics Based Identification of Specific Biochemical Changes Associated With PfKelch13-Mutant Artemisinin-Resistant Plasmodium falciparum. J Infect Dis 2017; 215:1435-1444. [PMID: 28368494 DOI: 10.1093/infdis/jix156] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/25/2017] [Indexed: 01/10/2023] Open
Abstract
Background The emergence of artemisinin resistance in the malaria parasite Plasmodium falciparum poses a major threat to the control and elimination of malaria. Certain point mutations in the propeller domain of PfKelch13 are associated with resistance, but PfKelch13 mutations do not always result in clinical resistance. The underlying mechanisms associated with artemisinin resistance are poorly understood, and the impact of PfKelch13 mutations on cellular biochemistry is not defined. Methods This study aimed to identify global biochemical differences between PfKelch13-mutant artemisinin-resistant and -sensitive strains of P. falciparum by combining liquid chromatography-mass spectrometry (LC-MS)-based proteomics, peptidomics, and metabolomics. Results Proteomics analysis found both PfKelch13 mutations examined to be specifically associated with decreased abundance of PfKelch13 protein. Metabolomics analysis demonstrated accumulation of glutathione and its precursor, gamma-glutamylcysteine, and significant depletion of 1 other putative metabolite in resistant strains. Peptidomics analysis revealed lower abundance of several endogenous peptides derived from hemoglobin (HBα and HBβ) in the artemisinin-resistant strains. Conclusion PfKelch13 mutations associated with artemisinin resistance lead to decreased abundance of PfKelch13 protein, decreased hemoglobin digestion, and enhanced glutathione production.
Collapse
Affiliation(s)
- Ghizal Siddiqui
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University,Parkville, Victoria, Australia
| | - Anubhav Srivastava
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University,Parkville, Victoria, Australia
| | - Adrian S Russell
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University,Parkville, Victoria, Australia
| | - Darren J Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University,Parkville, Victoria, Australia
| |
Collapse
|
6
|
Chaudhari R, Sharma S, Patankar S. Glutathione and thioredoxin systems of the malaria parasite Plasmodium falciparum: Partners in crime? Biochem Biophys Res Commun 2017; 488:95-100. [PMID: 28479253 DOI: 10.1016/j.bbrc.2017.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 05/03/2017] [Indexed: 11/25/2022]
Abstract
In P. falciparum, antioxidant proteins of the glutathione and thioredoxin systems are compartmentalized. Some subcellular compartments have only a partial complement of these proteins. This lack of key anti-oxidant proteins in certain sub-cellular compartments might be compensated by functional complementation between these systems. By assessing the cross-talk between these systems, we show for the first time, that the glutathione system can reduce thioredoxins that are poor substrates for thioredoxin reductase (Thioredoxin-like protein 1 and Thioredoxin 2) and thioredoxins that lack access to thioredoxin reductase (Thioredoxin 2). Our data suggests that crosstalk between the glutathione and thioredoxin systems does exist; this could compensate for the absence of certain antioxidant proteins from key subcellular compartments.
Collapse
Affiliation(s)
- Rahul Chaudhari
- Department of Biological Sciences, TIFR, Colaba, Mumbai 400005, India.
| | - Shobhona Sharma
- Department of Biological Sciences, TIFR, Colaba, Mumbai 400005, India.
| | - Swati Patankar
- Department of Biosciences & Bioengineering, IIT Bombay, Powai, Mumbai 400076, India.
| |
Collapse
|
7
|
Burkard L, Scheuermann A, Simithy J, Calderón AI. Development of a functional assay to detect inhibitors of Plasmodium falciparum glutathione reductase utilizing liquid chromatography-mass spectrometry. Biomed Chromatogr 2015; 30:543-7. [PMID: 26257195 DOI: 10.1002/bmc.3580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 07/23/2015] [Accepted: 08/03/2015] [Indexed: 12/20/2022]
Abstract
Plasmodium falciparum (Pf) like most other organisms, has a sophisticated antioxidant system, part of which includes glutathione reductase (GR). GR works by recycling toxic glutathione disulfide to glutathione, thereby reducing reactive oxygen species and making a form of glutathione (GSH) the parasite can use. Inhibition of this enzyme in Pf impedes parasite growth. In addition, it has been confirmed that PfGR is not identical to human GR. Thus, PfGR is an excellent target for antimalarial drug development. A functional assay utilizing liquid chromatography-mass spectrometry was developed to specifically identify and evaluate inhibitors of PfGR. Using recombinant PfGR enzyme and 1,4-naphthoquinone (1) as a reference compound and 4-nitrobenzothiadiazole (2) and methylene blue (3) as additional compounds, we quantified the concentration of GSH produced compared with a control to determine the inhibitory effect of these compounds. Our results coincide with that presented in literature: compounds 1-3 inhibit PfGR with IC50 values of 2.71, 8.38, and 19.23 µm, respectively. Good precision for this assay was exhibited by low values of intraday and interday coefficient of variation (3.1 and 2.4%, respectively). Thus, this assay can be used to screen for other potential inhibitors of PfGR quickly and accurately.
Collapse
Affiliation(s)
- Lexi Burkard
- Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA
| | - Alexis Scheuermann
- Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA
| | - Johayra Simithy
- Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA
| | - Angela I Calderón
- Department of Drug Discovery and Development, Harrison School of Pharmacy, 4306 Walker Building, Auburn University, Auburn, AL, 36849, USA
| |
Collapse
|
8
|
Role and Regulation of Glutathione Metabolism in Plasmodium falciparum. Molecules 2015; 20:10511-34. [PMID: 26060916 PMCID: PMC6272303 DOI: 10.3390/molecules200610511] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/11/2015] [Accepted: 06/01/2015] [Indexed: 11/30/2022] Open
Abstract
Malaria in humans is caused by one of five species of obligate intracellular protozoan parasites of the genus Plasmodium. P. falciparum causes the most severe disease and is responsible for 600,000 deaths annually, primarily in Sub-Saharan Africa. It has long been suggested that during their development, malaria parasites are exposed to environmental and metabolic stresses. One strategy to drug discovery was to increase these stresses by interfering with the parasites’ antioxidant and redox systems, which may be a valuable approach to disease intervention. Plasmodium possesses two redox systems—the thioredoxin and the glutathione system—with overlapping but also distinct functions. Glutathione is the most abundant low molecular weight redox active thiol in the parasites existing primarily in its reduced form representing an excellent thiol redox buffer. This allows for an efficient maintenance of the intracellular reducing environment of the parasite cytoplasm and its organelles. This review will highlight the mechanisms that are responsible for sustaining an adequate concentration of glutathione and maintaining its redox state in Plasmodium. It will provide a summary of the functions of the tripeptide and will discuss the potential of glutathione metabolism for drug discovery against human malaria parasites.
Collapse
|
9
|
Purification and characterization of glutathione reductase (E.C. 1.8.1.7) from bovine filarial worms Setaria cervi. J Parasit Dis 2014; 37:94-104. [PMID: 24431548 DOI: 10.1007/s12639-012-0138-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Accepted: 06/15/2012] [Indexed: 10/28/2022] Open
Abstract
Antioxidant enzymes are the parasite's premier resource to defend themselves against reactive oxygen species generated by macrophages, neutrophils and eosinophils of the host. These enzymes may be particularly important for parasites involved in chronic infections, such as parasitic helminths. Glutathione (GSH) and glutathione reductase (GR) are parts of the GSH redox cycle, which protects cells against damage by oxidants. Both GSH and GR are present in significant amounts in Setaria cervi female worms. GR has a central role in glutathione metabolism and as such is a potential target for chemotherapy. The aim of the work was to purify and characterize GR from S. cervi and to compare the properties of the helminth enzyme with its mammalian counterpart. GR was purified from filarial parasites S. cervi and preliminary steady state kinetics was performed. The purified protein was observed to be a dimer of 55 kDa subunit as evident from SDS-PAGE analysis. Kinetic studies revealed significant differences in the properties of S. cervi GR from its mammalian counterpart which may be exploited in chemotherapy of filariasis. Filarial GR is thus proposed as a potential drug target.
Collapse
|
10
|
Belorgey D, Lanfranchi DA, Davioud-Charvet E. 1,4-naphthoquinones and other NADPH-dependent glutathione reductase-catalyzed redox cyclers as antimalarial agents. Curr Pharm Des 2013; 19:2512-28. [PMID: 23116403 DOI: 10.2174/1381612811319140003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 11/22/2022]
Abstract
The homodimeric flavoenzyme glutathione reductase catalyzes NADPH-dependent glutathione disulfide reduction. This reaction is important for keeping the redox homeostasis in human cells and in the human pathogen Plasmodium falciparum. Different types of NADPH-dependent disulfide reductase inhibitors were designed in various chemical series to evaluate the impact of each inhibition mode on the propagation of the parasites. Against malaria parasites in cultures the most potent and specific effects were observed for redox-active agents acting as subversive substrates for both glutathione reductases of the Plasmodium-infected red blood cells. In their oxidized form, these redox-active compounds are reduced by NADPH-dependent flavoenzyme-catalyzed reactions in the cytosol of infected erythrocytes. In their reduced forms, these compounds can reduce molecular oxygen to reactive oxygen species, or reduce oxidants like methemoglobin, the major nutrient of the parasite, to indigestible hemoglobin. Furthermore, studies on a fluorinated suicide-substrate of the human glutathione reductase indicate that the glutathione reductase-catalyzed bioactivation of 3-benzylnaphthoquinones to the corresponding reduced 3-benzoyl metabolites is essential for the observed antimalarial activity. In conclusion, the antimalarial lead naphthoquinones are suggested to perturb the major redox equilibria of the targeted cells. These effects result in developmental arrest of the parasite and contribute to the removal of the parasitized erythrocytes by macrophages.
Collapse
Affiliation(s)
- Didier Belorgey
- European School of Chemistry, Polymers and Materials (ECPM), UMR7509 CNRS - Universite de Strasbourg, 25 rue Becquerel, F-67087 Strasbourg Cedex 2, France.
| | | | | |
Collapse
|
11
|
Abstract
SIGNIFICANCE Parasitic infections continue to be a major problem for global human health. Vaccines are practically not available and chemotherapy is highly unsatisfactory. One approach toward a novel antiparasitic drug development is to unravel pathways that may be suited as future targets. Parasitic organisms show a remarkable diversity with respect to the nature and functions of their main low-molecular-mass antioxidants and many of them developed pathways that do not have a counterpart in their mammalian hosts. RECENT ADVANCES Work of the last years disclosed the individual antioxidants employed by parasites and their distinct pathways. Entamoeba, Trichomonas, and Giardia directly use cysteine as main low-molecular-mass thiol but have divergent cysteine metabolisms. Malarial parasites rely exclusively on cysteine uptake and generate glutathione (GSH) as main free thiol as do metazoan parasites. Trypanosomes and Leishmania have a unique trypanothione-based thiol metabolism but employ individual mechanisms for their cysteine supply. In addition, some trypanosomatids synthesize ovothiol A and/or ascorbate. Various essential parasite enzymes such as trypanothione synthetase and trypanothione reductase in Trypanosomatids and the Schistosoma thioredoxin GSH reductase are currently intensively explored as drug target molecules. CRITICAL ISSUES Essentiality is a prerequisite but not a sufficient property of an enzyme to become a suited drug target. The availability of an appropriate in vivo screening system and many other factors are equally important. FUTURE DIRECTIONS The current organism-wide RNA-interference and proteome analyses are supposed to reveal many more interesting candidates for future drug development approaches directed against the parasite antioxidant defense systems.
Collapse
|
12
|
Abstract
SIGNIFICANCE Cysteine residues of proteins participate in the catalysis of biochemical reactions, are crucial for redox reactions, and influence protein structure by the formation of disulfide bonds. Covalent posttranslational modifications (PTMs) of cysteine residues are important mediators of redox regulation and signaling by coupling protein activity to the cellular redox state, and moreover influence stability, function, and localization of proteins. A diverse group of protozoan and metazoan parasites are a major cause of diseases in humans, such as malaria, African trypanosomiasis, leishmaniasis, toxoplasmosis, filariasis, and schistosomiasis. RECENT ADVANCES Human parasites undergo dramatic morphological and metabolic changes while they pass complex life cycles and adapt to changing environments in host and vector. These processes are in part regulated by PTMs of parasitic proteins. In human parasites, posttranslational cysteine modifications are involved in crucial cellular events such as signal transduction (S-glutathionylation and S-nitrosylation), redox regulation of proteins (S-glutathionylation and S-nitrosylation), protein trafficking and subcellular localization (palmitoylation and prenylation), as well as invasion into and egress from host cells (palmitoylation). This review focuses on the occurrence and mechanisms of these cysteine modifications in parasites. CRITICAL ISSUES Studies on cysteine modifications in human parasites are so far largely based on in vitro experiments. FUTURE DIRECTIONS The in vivo regulation of cysteine modifications and their role in parasite development will be of great interest in order to understand redox signaling in parasites.
Collapse
Affiliation(s)
- Esther Jortzik
- Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
| | | | | |
Collapse
|
13
|
Zocher K, Fritz-Wolf K, Kehr S, Fischer M, Rahlfs S, Becker K. Biochemical and structural characterization of Plasmodium falciparum glutamate dehydrogenase 2. Mol Biochem Parasitol 2012; 183:52-62. [DOI: 10.1016/j.molbiopara.2012.01.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 01/23/2012] [Accepted: 01/31/2012] [Indexed: 02/01/2023]
|
14
|
Baroni S, Pandini V, Vanoni MA, Aliverti A. A single tyrosine hydroxyl group almost entirely controls the NADPH specificity of Plasmodium falciparum ferredoxin-NADP+ reductase. Biochemistry 2012; 51:3819-26. [PMID: 22519987 DOI: 10.1021/bi300078p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plasmodium falciparum ferredoxin-NADP(+) reductase (FNR) is a FAD-containing enzyme that, in addition to be a promising target of novel antimalarial drugs, represents an excellent model of plant-type FNRs. The cofactor specificity of FNRs depends on differences in both k(cat) and K(m) values for NADPH and NADH. Here, we report that deletion of the hydroxyl group of the conserved Y258 of P. falciparum FNR, which interacts with the 2'-phosphate group of NADPH, selectively decreased the k(cat) of the NADPH-dependent reaction by a factor of 2 to match that of the NADH-dependent one. Rapid-reaction kinetics, active-site titrations with NADP(+), and anaerobic photoreduction experiments indicated that this effect may be the consequence of destabilization of the catalytically competent conformation of bound NADPH. Moreover, because the Y258F replacement increased the K(m) for NADPH 4-fold and decreased that for NADH 3-fold, it led to a drop in the ability of the enzyme to discriminate between the coenzymes from 70- to just 1.5-fold. The impact of the Y258F change was not affected by the presence of the H286Q mutation, which is known to enhance the catalytic activity of the enzyme. Our data highlight the major role played by the Y258 hydroxyl group in determining the coenzyme specificity of P. falciparum FNR. From the general standpoint of engineering the kinetic properties of plant-type FNRs, although P. falciparum FNR is less strictly NADPH-dependent than its homologues, the almost complete abolishment of coenzyme selectivity reported here has never been accomplished before through a single mutation.
Collapse
Affiliation(s)
- Sara Baroni
- Department of Biomolecular Sciences and Biotechnology, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | | | | | | |
Collapse
|
15
|
Selim M, Saha A, Mukherjea KK. Synthesis, characterization, and DNA binding of the biologically relevant novel cationic molybdenum(VI)–glutathione complex [Mo(GS)(Cl)(H2O)]Cl2. MONATSHEFTE FUR CHEMIE 2011. [DOI: 10.1007/s00706-011-0601-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
16
|
Storm J, Perner J, Aparicio I, Patzewitz EM, Olszewski K, Llinas M, Engel PC, Müller S. Plasmodium falciparum glutamate dehydrogenase a is dispensable and not a drug target during erythrocytic development. Malar J 2011; 10:193. [PMID: 21756354 PMCID: PMC3163627 DOI: 10.1186/1475-2875-10-193] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 07/14/2011] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium falciparum contains three genes encoding potential glutamate dehydrogenases. The protein encoded by gdha has previously been biochemically and structurally characterized. It was suggested that it is important for the supply of reducing equivalents during intra-erythrocytic development of Plasmodium and, therefore, a suitable drug target. Methods The gene encoding the NADP(H)-dependent GDHa has been disrupted by reverse genetics in P. falciparum and the effect on the antioxidant and metabolic capacities of the resulting mutant parasites was investigated. Results No growth defect under low and elevated oxygen tension, no up- or down-regulation of a number of antioxidant and NADP(H)-generating proteins or mRNAs and no increased levels of GSH were detected in the D10Δgdha parasite lines. Further, the fate of the carbon skeleton of [13C] labelled glutamine was assessed by metabolomic studies, revealing no differences in the labelling of α-ketoglutarate and other TCA pathway intermediates between wild type and mutant parasites. Conclusions First, the data support the conclusion that D10Δgdha parasites are not experiencing enhanced oxidative stress and that GDHa function may not be the provision of NADP(H) for reductive reactions. Second, the results imply that the cytosolic, NADP(H)-dependent GDHa protein is not involved in the oxidative deamination of glutamate but that the protein may play a role in ammonia assimilation as has been described for other NADP(H)-dependent GDH from plants and fungi. The lack of an obvious phenotype in the absence of GDHa may point to a regulatory role of the protein providing glutamate (as nitrogen storage molecule) in situations where the parasites experience a limiting supply of carbon sources and, therefore, under in vitro conditions the enzyme is unlikely to be of significant importance. The data imply that the protein is not a suitable target for future drug development against intra-erythrocytic parasite development.
Collapse
Affiliation(s)
- Janet Storm
- Institute of Infection, Immunity & Inflammation, Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Life Sciences, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Buchholz K, Putrianti ED, Rahlfs S, Schirmer RH, Becker K, Matuschewski K. Molecular genetics evidence for the in vivo roles of the two major NADPH-dependent disulfide reductases in the malaria parasite. J Biol Chem 2010; 285:37388-95. [PMID: 20852334 PMCID: PMC2988344 DOI: 10.1074/jbc.m110.123323] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 08/27/2010] [Indexed: 11/06/2022] Open
Abstract
Malaria-associated pathology is caused by the continuous expansion of Plasmodium parasites inside host erythrocytes. To maintain a reducing intracellular milieu in an oxygen-rich environment, malaria parasites have evolved a complex antioxidative network based on two central electron donors, glutathione and thioredoxin. Here, we dissected the in vivo roles of both redox pathways by gene targeting of the respective NADPH-dependent disulfide reductases. We show that Plasmodium berghei glutathione reductase and thioredoxin reductase are dispensable for proliferation of the pathogenic blood stages. Intriguingly, glutathione reductase is vital for extracellular parasite development inside the insect vector, whereas thioredoxin reductase is dispensable during the entire parasite life cycle. Our findings suggest that glutathione reductase is the central player of the parasite redox network, whereas thioredoxin reductase fulfils a specialized and dispensable role for P. berghei. These results also indicate redundant roles of the Plasmodium redox pathways during the pathogenic blood phase and query their suitability as promising drug targets for antimalarial intervention strategies.
Collapse
Affiliation(s)
- Kathrin Buchholz
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
- the Biochemistry Centre, Ruprecht-Karls University, Heidelberg 69120, Germany
- the Department of Parasitology, Heidelberg University School of Medicine, Heidelberg 69120, Germany, and
| | - Elyzana D. Putrianti
- the Parasitology Unit, Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Stefan Rahlfs
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
| | - R. Heiner Schirmer
- the Biochemistry Centre, Ruprecht-Karls University, Heidelberg 69120, Germany
| | - Katja Becker
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
| | - Kai Matuschewski
- the Parasitology Unit, Max Planck Institute for Infection Biology, Berlin 10117, Germany
| |
Collapse
|
18
|
Can B, Kulaksiz Erkmen G, Dalmizrak O, Ogus IH, Ozer N. Purification and characterisation of rat kidney glutathione reductase. Protein J 2010; 29:250-6. [PMID: 20490902 DOI: 10.1007/s10930-010-9246-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glutathione reductase [GR, E.C.1.8.1.7] catalyses NADPH dependent reduction of glutathione disulfide (GSSG) to reduced glutathione (GSH). Thus, it is the crucial enzyme to maintain high [GSH]/[GSSG] ratio and physiological redox status in cells. Kidney and liver tissues were considered as a rich source of GR. In this study, rat kidney GR was purified and some of its properties were investigated. The enzyme was purified 2,356 fold with a yield of 16% by using heat-denaturation and Sephadex G25 gel filtration, 2',5'-ADP Agarose 4B, PBE94 column chromatographies. The purified enzyme had a specific activity (Vm) of 250 U/mg protein and the ratio of absorbances at wavelengths of A (273)/A (463,) A (280)/A (460), A (365)/A (460), and A (379)/A (463), were 7.1, 6.8, 1.2 and 1.0, respectively. Each mol of GR subunit bound 0.97 mol of FAD. NADH was used as a coenzyme by rat kidney GR but with a lower efficiency (32.7%) than NADPH. Its subunit molecular weight was estimated as 53 kDa. An optimum pH of 6.5 and optimum temperature of 65 degrees C were found for rat kidney GR. Its activation energy (Ea) and temperature coefficient (Q(10)) were calculated as 7.02 kcal/mol and 1.42, respectively. The Km((NADPH)) and kcat/Km ((NADPH)) values were found to be 15.3 +/- 1.4 microM and 1.68 x 10(7) M(-1) s(-1) for the concentration range of 10-200 microM NADPH and when GSSG is the variable substrate, the Km((GSSG)) and the kcat/Km((GSSG)) values of 53.1 +/- 3.4 microM and 4.85 x 10(6) M(-1) s(-1) were calculated for the concentration range of 20-1,200 microM GSSG.
Collapse
Affiliation(s)
- Betul Can
- Department of Biochemistry, Hacettepe University, Sihhiye, Ankara, Turkey
| | | | | | | | | |
Collapse
|
19
|
Wisedpanichkij R, Chaicharoenkul W, Mahamad P, Prompradit P, Na-Bangchang K. Polymorphisms of the oxidant enzymes glutathione S–transferase and glutathione reductase and their association with resistance of Plasmodium falciparum isolates to antimalarial drugs. ASIAN PAC J TROP MED 2010. [DOI: 10.1016/s1995-7645(10)60163-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
20
|
Characterization of the glutamate dehydrogenase activity of Gigantocotyle explanatum and Gastrothylax crumenifer (Trematoda: Digenea). J Parasit Dis 2010; 33:57-64. [PMID: 23129890 DOI: 10.1007/s12639-009-0010-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 12/08/2009] [Indexed: 10/19/2022] Open
Abstract
Glutamate dehydrogenase (GLDH) (EC 1.4.1.3) is a ubiquitous enzyme, which is present at the protein and carbohydrate metabolism crossroads. The enzyme activity was investigated in biliary and rumen amphistomes, Gigantocotyle explanatum and Gastrothylax crumenifer, respectively, infecting the Indian water buffalo Bubalus bubalis. The enzyme activity was consistently higher in G. explanatum as compared to G. crumenifer, where NAD(H) was utilized as coenzyme and the pH optima was recorded at 8. The K(m) and V(max) values for α-ketoglutarate were 2.1 mM and 9.09 units in G. explanatum, whereas 3.03 mM and 1.90 units in G. crumenifer, respectively. Among the allosteric modulator nucleotides, AMP, ADP, ATP, GMP, CMP and UMP, only AMP enhanced GLDH activity in G. crumenifer while ADP was stimulatory in G. explanatum. The amino acid leucine stimulated the GLDH activity in both the amphistomes while alanine was stimulatory only in G. crumenifer. Pronounced interspecific differences in response to different metabolic inhibitors like diethyldithiocarbamate, semicarbazide hydrochloride and mercurial ions were also observed. The osmotic stress alters the enzyme activity, particularly in hypertonic saline the GLDH activity increased significantly (p < 0.01) in G. explanatum, while insignificant effects were observed in rumen dwelling G. crumenifer. Histoenzymology revealed region/tissue specific distribution of GLDH with prominent staining in tissues like vitellaria, lymph system and tegument/subtegument, thus showing specific distribution of GLDH indicating differential metabolic state. Such intergeneric differences in GLDH activity could also be a consequence of occupying different microenvironments within the same host.
Collapse
|
21
|
Kapoor G, Banyal HS. Glutathione reductase and thioredoxin reductase: novel antioxidant enzymes from Plasmodium berghei. THE KOREAN JOURNAL OF PARASITOLOGY 2009; 47:421-4. [PMID: 19967095 DOI: 10.3347/kjp.2009.47.4.421] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Revised: 07/30/2009] [Accepted: 08/03/2009] [Indexed: 11/23/2022]
Abstract
Malaria parasites adapt to the oxidative stress during their erythrocytic stages with the help of vital thioredoxin redox system and glutathione redox system. Glutathione reductase and thioredoxin reductase are important enzymes of these redox systems that help parasites to maintain an adequate intracellular redox environment. In the present study, activities of glutathione reductase and thioredoxin reductase were investigated in normal and Plasmodium berghei-infected mice red blood cells and their fractions. Activities of glutathione reductase and thioredoxin reductase in P. berghei-infected host erythrocytes were found to be higher than those in normal host cells. These enzymes were mainly confined to the cytosolic part of cell-free P. berghei. Full characterization and understanding of these enzymes may promise advances in chemotherapy of malaria.
Collapse
Affiliation(s)
- Gaurav Kapoor
- Laboratory of Parasitology and Immunology, Department of Biosciences, Himachal Pradesh University, Shimla 171005, India
| | | |
Collapse
|
22
|
Singh BK, Sharma RK, Garg BS. Cobalt(II) complexes of biologically active glutathione: spectroscopic and molecular modeling studies. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2006; 63:96-102. [PMID: 16344245 DOI: 10.1016/j.saa.2005.04.055] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 04/22/2005] [Accepted: 04/22/2005] [Indexed: 05/05/2023]
Abstract
Cobalt(II) complexes of reduced glutathione (GSH) of general composition Na[Co(L)(X)].nH2O (where H2L = GSH; X = Cl-, NO3-, NCS-, CH3CO2-, HCO2-, ClO4- and n = 0-4) have been synthesized and characterised by elemental analyses, vibrational spectra, electronic spectra, magnetic susceptibility measurements, thermal studies and molecular modeling studies. Electronic spectra indicate planar geometry for all the complexes. Infrared spectra indicate the presence of H2O molecules (except perchlorate complex) in the complexes that has been supported by TG/DTA. The room temperature magnetic moment values for all complexes lie in the range of 2.60-2.80 BM range indicating departure from spin only values due to second order Zeeman effect. Thermal decomposition of all the complexes proceeds via first order kinetics. The Na[Co(L)(Cl)].2H2O complex has the minimum activation energy and Na[Co(L)(CH3CO2)].3H2O has the maximum activation energy. The molecular modeling calculation for energy minimization optimizes geometry of the metal complexes.
Collapse
Affiliation(s)
- Bibhesh K Singh
- Department of Chemistry, University of Delhi, Delhi 110007, India.
| | | | | |
Collapse
|
23
|
Abstract
Hydroperoxide metabolism in diverse pathogens is reviewed under consideration of involved enzymes as potential drug targets. The common denominator of the peroxidase systems of Trypanosoma, Leishmania, Plasmodium, and Mycobacterium species is the use of NAD(P)H to reduce hydroperoxides including peroxynitrite via a flavin-containing disulfide reductase, a thioredoxin (Trx)-related protein and a peroxidase that operates with thiol catalysis. In Plasmodium falciparum, thioredoxin- and glutathione dependent systems appear to be linked via glutaredoxin and plasmoredoxin to terminal thioredoxin peroxidases belonging to both, the peroxiredoxin (Prx) and glutathione peroxidase (GPx) family. In Mycobacterium tuberculosis, a catalase-type peroxidase is complemented by the typical 2-C-Prx AhpC that, in contrast to most bacteria, is reduced by TrxC, and an atypical 2-C-Prx reduced by TrxB or C. A most complex variation of the scheme is found in trypanosomatids, where the unique redox metabolite trypanothione reduces the thioredoxin-related tryparedoxin, which fuels Prx- and GPx-type peroxidases as well as ribonucleotide reductase. In Trypanosoma brucei and Leishmania donovani the system has been shown to be essential for viability and virulence by inversed genetics. It is concluded that optimum efficacy can be expected from inhibitors of the most upstream components of the redox cascades. For trypanosomatids attractive validated drug targets are trypanothione reductase and trypanothione synthetase; for mycobacteria thioredoxin reductase appears most appealing, while in Plasmodium simultaneous inhibition of both the thioredoxin and the glutathione pathway appears advisable to avoid mutual substitution in co-substrate supply to the peroxidases. Financial and organisational needs to translate the scientific progress into applicable drugs are discussed under consideration of the socio-economic impact of the addressed diseases.
Collapse
Affiliation(s)
- Timo Jaeger
- MOLISA GmbH, Molecular Links Sachsen-Anhalt, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | | |
Collapse
|
24
|
Singh BK, Sharma RK, Garg BS. Characterization, kinetics of thermal decomposition and molecular modeling studies on mercury (II) complexes of biologically active glutathione. MAIN GROUP CHEMISTRY 2005. [DOI: 10.1080/10241220600834925] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
25
|
Schwarz R, Musch P, von Kamp A, Engels B, Schirmer H, Schuster S, Dandekar T. YANA - a software tool for analyzing flux modes, gene-expression and enzyme activities. BMC Bioinformatics 2005; 6:135. [PMID: 15929789 PMCID: PMC1175843 DOI: 10.1186/1471-2105-6-135] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Accepted: 06/01/2005] [Indexed: 11/22/2022] Open
Abstract
Background A number of algorithms for steady state analysis of metabolic networks have been developed over the years. Of these, Elementary Mode Analysis (EMA) has proven especially useful. Despite its low user-friendliness, METATOOL as a reliable high-performance implementation of the algorithm has been the instrument of choice up to now. As reported here, the analysis of metabolic networks has been improved by an editor and analyzer of metabolic flux modes. Analysis routines for expression levels and the most central, well connected metabolites and their metabolic connections are of particular interest. Results YANA features a platform-independent, dedicated toolbox for metabolic networks with a graphical user interface to calculate (integrating METATOOL), edit (including support for the SBML format), visualize, centralize, and compare elementary flux modes. Further, YANA calculates expected flux distributions for a given Elementary Mode (EM) activity pattern and vice versa. Moreover, a dissection algorithm, a centralization algorithm, and an average diameter routine can be used to simplify and analyze complex networks. Proteomics or gene expression data give a rough indication of some individual enzyme activities, whereas the complete flux distribution in the network is often not known. As such data are noisy, YANA features a fast evolutionary algorithm (EA) for the prediction of EM activities with minimum error, including alerts for inconsistent experimental data. We offer the possibility to include further known constraints (e.g. growth constraints) in the EA calculation process. The redox metabolism around glutathione reductase serves as an illustration example. All software and documentation are available for download at . Conclusion A graphical toolbox and an editor for METATOOL as well as a series of additional routines for metabolic network analyses constitute a new user-friendly software for such efforts.
Collapse
Affiliation(s)
- Roland Schwarz
- Dept of Bioinformatics, Biocenter, University of Würzburg; Germany
| | - Patrick Musch
- Dept of Theoretical Chemistry, Organikum, University of Würzburg, Germany
| | | | - Bernd Engels
- Dept of Theoretical Chemistry, Organikum, University of Würzburg, Germany
| | - Heiner Schirmer
- Center for Biochemistry (BZH), University of Heidelberg, Germany
| | | | - Thomas Dandekar
- Dept of Bioinformatics, Biocenter, University of Würzburg; Germany
- Structural and Computational Biology, EMBL, Heidelberg, Germany
| |
Collapse
|
26
|
Werner C, Stubbs MT, Krauth-Siegel RL, Klebe G. The crystal structure of Plasmodium falciparum glutamate dehydrogenase, a putative target for novel antimalarial drugs. J Mol Biol 2005; 349:597-607. [PMID: 15878595 DOI: 10.1016/j.jmb.2005.03.077] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Revised: 03/07/2005] [Accepted: 03/09/2005] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum is the main causative agent of tropical malaria, the most severe parasitic disease in the world. Growing resistance of Plasmodia towards available drugs is an increasing problem in countries where malaria is endemic. As Plasmodia are sensitive to oxidative stress, augmenting this in the parasite represents a promising principle for the development of novel antimalarial drugs. The NADP-dependent glutamate dehydrogenase (GDH) of P.falciparum is largely responsible for the production of NADPH in the parasite, which in turn serves as electron source for the antioxidative enzymes glutathione reductase and thioredoxin reductase. As GDH does not occur in the host erythrocyte, GDH is a particularly attractive target for drug therapy. The three-dimensional structure of P.falciparum GDH in the unligated state has been determined by X-ray crystallography to a resolution of 2.7A. Compared to the mammalian enzymes, two amino acid residues are exchanged in the putative active site of the parasite GDH. The most obvious differences between parasite and human GDH are the subunit interfaces of the hexameric proteins. In the parasite protein, several salt-bridges mediate contacts between the subunits whereas in the human enzyme these interactions are mainly of hydrophobic nature. Furthermore, P.falciparum GDH possesses a unique N-terminal extension that does not occur in any other GDH sequence so far studied. These findings might be exploited for the design of peptidomimetics capable of disrupting the oligomeric organisation of the parasite enzyme.
Collapse
Affiliation(s)
- Christof Werner
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6, D-35037 Marburg, Germany
| | | | | | | |
Collapse
|
27
|
Krauth-Siegel RL, Bauer H, Schirmer RH. Dithiol Proteins as Guardians of the Intracellular Redox Milieu in Parasites: Old and New Drug Targets in Trypanosomes and Malaria-Causing Plasmodia. Angew Chem Int Ed Engl 2005; 44:690-715. [PMID: 15657967 DOI: 10.1002/anie.200300639] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Parasitic diseases such as sleeping sickness, Chagas' heart disease, and malaria are major health problems in poverty-stricken areas. Antiparasitic drugs that are not only active but also affordable and readily available are urgently required. One approach to finding new drugs and rediscovering old ones is based on enzyme inhibitors that paralyze antioxidant systems in the pathogens. These antioxidant ensembles are essential to the parasites as they are attacked in the human host by strong oxidants such as peroxynitrite, hypochlorite, and H2O2. The pathogen-protecting system consists of some 20 thiol and dithiol proteins, which buffer the intraparasitic redox milieu at a potential of -250 mV. In trypanosomes and leishmania the network is centered around the unique dithiol trypanothione (N1,N8-bis(glutathionyl)spermidine). In contrast, malaria parasites have a more conservative dual antioxidative system based on glutathione and thioredoxin. Inhibitors of antioxidant enzymes such as trypanothione reductase are, indeed, parasiticidal but they can also delay or prevent resistance against a number of other antiparasitic drugs.
Collapse
Affiliation(s)
- R Luise Krauth-Siegel
- Universität Heidelberg, Biochemie-Zentrum, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany.
| | | | | |
Collapse
|
28
|
Krauth-Siegel RL, Bauer H, Schirmer RH. Dithiolproteine als Hüter des intrazellulären Redoxmilieus bei Parasiten: alte und neue Wirkstoff-Targets bei Trypanosomiasis und Malaria. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200300639] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
29
|
Bozdech Z, Ginsburg H. Antioxidant defense in Plasmodium falciparum--data mining of the transcriptome. Malar J 2004; 3:23. [PMID: 15245577 PMCID: PMC514526 DOI: 10.1186/1475-2875-3-23] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Accepted: 07/09/2004] [Indexed: 01/28/2023] Open
Abstract
The intraerythrocytic malaria parasite is under constant oxidative stress originating both from endogenous and exogenous processes. The parasite is endowed with a complete network of enzymes and proteins that protect it from those threats, but also uses redox activities to regulate enzyme activities. In the present analysis, the transcription of the genes coding for the antioxidant defense elements are viewed in the time-frame of the intraerythrocytic cycle. Time-dependent transcription data were taken from the transcriptome of the human malaria parasite Plasmodium falciparum. Whereas for several processes the transcription of the many participating genes is coordinated, in the present case there are some outstanding deviations where gene products that utilize glutathione or thioredoxin are transcribed before the genes coding for elements that control the levels of those substrates are transcribed. Such insights may hint to novel, non-classical pathways that necessitate further investigations.
Collapse
Affiliation(s)
- Zbynek Bozdech
- Department of Biochemistry and Biophysics, University of California San Francisco, 600 16Str, San Francisco, CA 94143-0448, USA
| | - Hagai Ginsburg
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| |
Collapse
|
30
|
Becker K, Tilley L, Vennerstrom JL, Roberts D, Rogerson S, Ginsburg H. Oxidative stress in malaria parasite-infected erythrocytes: host–parasite interactions. Int J Parasitol 2004; 34:163-89. [PMID: 15037104 DOI: 10.1016/j.ijpara.2003.09.011] [Citation(s) in RCA: 420] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Revised: 09/18/2003] [Accepted: 09/18/2003] [Indexed: 01/09/2023]
Abstract
Experimenta naturae, like the glucose-6-phosphate dehydrogenase deficiency, indicate that malaria parasites are highly susceptible to alterations in the redox equilibrium. This offers a great potential for the development of urgently required novel chemotherapeutic strategies. However, the relationship between the redox status of malarial parasites and that of their host is complex. In this review article we summarise the presently available knowledge on sources and detoxification pathways of reactive oxygen species in malaria parasite-infected red cells, on clinical aspects of redox metabolism and redox-related mechanisms of drug action as well as future prospects for drug development. As delineated below, alterations in redox status contribute to disease manifestation including sequestration, cerebral pathology, anaemia, respiratory distress, and placental malaria. Studying haemoglobinopathies, like thalassemias and sickle cell disease, and other red cell defects that provide protection against malaria allows insights into this fine balance of redox interactions. The host immune response to malaria involves phagocytosis as well as the production of nitric oxide and oxygen radicals that form part of the host defence system and also contribute to the pathology of the disease. Haemoglobin degradation by the malarial parasite produces the redox active by-products, free haem and H(2)O(2), conferring oxidative insult on the host cell. However, the parasite also supplies antioxidant moieties to the host and possesses an efficient enzymatic antioxidant defence system including glutathione- and thioredoxin-dependent proteins. Mechanistic and structural work on these enzymes might provide a basis for targeting the parasite. Indeed, a number of currently used drugs, especially the endoperoxide antimalarials, appear to act by increasing oxidant stress, and novel drugs such as peroxidic compounds and anthroquinones are being developed.
Collapse
Affiliation(s)
- Katja Becker
- Interdisciplinary Research Center, Heinrich-Buff-Ring 26-32, Justus-Liebig University, D-35392 Giessen, Germany.
| | | | | | | | | | | |
Collapse
|
31
|
Bauer H, Gromer S, Urbani A, Schnölzer M, Schirmer RH, Müller HM. Thioredoxin reductase from the malaria mosquito Anopheles gambiae. ACTA ACUST UNITED AC 2003; 270:4272-81. [PMID: 14622292 DOI: 10.1046/j.1432-1033.2003.03812.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mosquito, Anopheles gambiae, is an important vector of Plasmodium falciparum malaria. Full genome analysis revealed that, as in Drosophila melanogaster, the enzyme glutathione reductase is absent in A. gambiae and functionally substituted by the thioredoxin system. The key enzyme of this system is thioredoxin reductase-1, a homodimeric FAD-containing protein of 55.3 kDa per subunit, which catalyses the reaction NADPH + H+ + thioredoxin disulfide-->NADP+ + thioredoxin dithiol. The A. gambiae trxr gene is located on chromosome X as a single copy; it represents three splice variants coding for two cytosolic and one mitochondrial variant. The predominant isoform, A. gambiae thioredoxin reductase-1, was recombinantly expressed in Escherichia coli and functionally compared with the wild-type enzyme isolated in a final yield of 1.4 U.ml(-1) of packed insect cells. In redox titrations, the substrate A. gambiae thioredoxin-1 (Km=8.5 microm, kcat=15.4 s(-1) at pH 7.4 and 25 degrees C) was unable to oxidize NADPH-reduced A. gambiae thioredoxin reductase-1 to the fully oxidized state. This indicates that, in contrast to other disulfide reductases, A. gambiae thioredoxin reductase-1 oscillates during catalysis between the four-electron reduced state and a two-electron reduced state. The thioredoxin reductases of the malaria system were compared. A. gambiae thioredoxin reductase-1 shares 52% and 45% sequence identity with its orthologues from humans and P. falciparum, respectively. A major difference among the three enzymes is the structure of the C-terminal redox centre, reflected in the varying resistance of catalytic intermediates to autoxidation. The relevant sequences of this centre are Thr-Cys-Cys-SerOH in A. gambiae thioredoxin reductase, Gly-Cys-selenocysteine-GlyOH in human thioredoxin reductase, and Cys-X-X-X-X-Cys-GlyOH in the P. falciparum enzyme. These differences offer an interesting approach to the design of species-specific inhibitors. Notably, A. gambiae thioredoxin reductase-1 is not a selenoenzyme but instead contains a highly unusual redox-active Cys-Cys sequence.
Collapse
Affiliation(s)
- Holger Bauer
- Biochemie Zentrum, Universität Heidelberg, Heidelberg, Germany
| | | | | | | | | | | |
Collapse
|
32
|
Minami Y, Kohama T, Sekimoto YJ, Akasaka K, Matsubara H. Isolation and characterization of glutathione reductase from Physarum polycephalum and stage-specific expression of the enzyme in life-cycle stages with different oxidation-reduction levels. J Eukaryot Microbiol 2003; 50:317-23. [PMID: 14563169 DOI: 10.1111/j.1550-7408.2003.tb00142.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Physarum polycephalum has a life cycle with several distinct phases that have different oxidation-reduction requirements. To investigate the relationship between the life cycle and the oxidation-reduction state, we isolated glutathione reductase (GR; EC 1.6.4.2) from Physarum microplasmodia. The enzyme was found to be a homodimer with a subunit M(r) of 49,000, and K(m) values for oxidized glutathione and NADPH of 40 and 28.6 microM, respectively. We then constructed a cDNA library from microplasmodium mRNA and cloned GR cDNA from the library. The isolated cDNA consisted of 1,475 bp encoding a polypeptide of 452 amino acids. The amino acid sequence similarity was about 50% with GRs of other organisms, and several conserved sequence motifs thought to be necessary for activity are evident in the Physarum enzyme. Escherichia coli transformed with an expression vector containing the cDNA synthesized the active GR. Genomic Southern blot analysis indicated that the GR gene is present as a single copy in the Physarum genome. Immunoblot analysis and RT-PCR analysis detected GR mRNA expression in the microplasmodium, plasmodium, and sclerotium, but not in the spore or flagellate. GR activity was low in the spore and flagellate. These results suggest that the glutathione oxidation-reduction system relates to the Physarum life cycle.
Collapse
Affiliation(s)
- Yoshiko Minami
- Department of Biochemistry, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan.
| | | | | | | | | |
Collapse
|
33
|
Sarma GN, Savvides SN, Becker K, Schirmer M, Schirmer RH, Karplus PA. Glutathione reductase of the malarial parasite Plasmodium falciparum: crystal structure and inhibitor development. J Mol Biol 2003; 328:893-907. [PMID: 12729762 DOI: 10.1016/s0022-2836(03)00347-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The malarial parasite Plasmodium falciparum is known to be sensitive to oxidative stress, and thus the antioxidant enzyme glutathione reductase (GR; NADPH+GSSG+H(+) <==> NADP(+)+2 GSH) has become an attractive drug target for antimalarial drug development. Here, we report the 2.6A resolution crystal structure of P.falciparum GR. The homodimeric flavoenzyme is compared to the related human GR with focus on structural aspects relevant for drug design. The most pronounced differences between the two enzymes concern the shape and electrostatics of a large (450A(3)) cavity at the dimer interface. This cavity binds numerous non-competitive inhibitors and is a target for selective drug design. A 34-residue insertion specific for the GRs of malarial parasites shows no density, implying that it is disordered. The precise location of this insertion along the sequence allows us to explain the deleterious effects of a mutant in this region and suggests new functional studies. To complement the structural comparisons, we report the relative susceptibility of human and plasmodial GRs to a series of tricyclic inhibitors as well as to peptides designed to interfere with protein folding and dimerization. Enzyme-kinetic studies on GRs from chloroquine-resistant and chloroquine-sensitive parasite strains were performed and indicate that the structure reported here represents GR of P.falciparum strains in general and thus is a highly relevant target for drug development.
Collapse
Affiliation(s)
- G N Sarma
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7305, USA
| | | | | | | | | | | |
Collapse
|
34
|
Becker K, Rahlfs S, Nickel C, Schirmer RH. Glutathione--functions and metabolism in the malarial parasite Plasmodium falciparum. Biol Chem 2003; 384:551-66. [PMID: 12751785 DOI: 10.1515/bc.2003.063] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
When present as a trophozoite in human erythrocytes, the malarial parasite Plasmodium falciparum exhibits an intense glutathione metabolism. Glutathione plays a role not only in antioxidative defense and in maintaining the reducing environment of the cytosol. Many of the known glutathione-dependent processes are directly related to the specific lifestyle of the parasite. Reduced glutathione (GSH) supports rapid cell growth by providing electrons for deoxyribonucleotide synthesis and it takes part in detoxifying heme, a product of hemoglobin digestion. Free radicals generated in the parasite can be scavenged in reaction sequences involving the thiyl radical GS* as well as the thiolate GS-. As a substrate of glutathione S-transferase, glutathione is conjugated to non-degradable compounds including antimalarial drugs. Furthermore, it is the coenzyme of the glyoxalase system which detoxifies methylglyoxal, a byproduct of the intense glycolysis taking place in the trophozoite. Proteins involved in GSH-dependent processes include glutathione reductase, glutaredoxins, glyoxalase I and II, glutathione S-transferases, and thioredoxins. These proteins, as well as the ATP-dependent enzymes of glutathione synthesis, are studied as factors in the pathophysiology of malaria but also as potential drug targets. Methylene blue, an inhibitor of the structurally known P. falciparum glutathione reductase, appears to be a promising antimalarial medication when given in combination with chloroquine.
Collapse
Affiliation(s)
- Katja Becker
- Interdisciplinary Research Center, Justus-Liebig-University, D-35392 Giessen, Germany
| | | | | | | |
Collapse
|
35
|
Meierjohann S, Walter RD, Müller S. Regulation of intracellular glutathione levels in erythrocytes infected with chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum. Biochem J 2002; 368:761-8. [PMID: 12225291 PMCID: PMC1223037 DOI: 10.1042/bj20020962] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2002] [Revised: 09/03/2002] [Accepted: 09/12/2002] [Indexed: 11/17/2022]
Abstract
Malaria is one of the most devastating tropical diseases despite the availability of numerous drugs acting against the protozoan parasite Plasmodium in its human host. However, the development of drug resistance renders most of the existing drugs useless. In the malaria parasite the tripeptide glutathione is not only involved in maintaining an adequate intracellular redox environment and protecting the cell against oxidative stress, but it has also been shown that it degrades non-polymerized ferriprotoporphyrin IX (FP IX) and is thus implicated in the development of chloroquine resistance. Glutathione levels in Plasmodium -infected red blood cells are regulated by glutathione synthesis, glutathione reduction and glutathione efflux. Therefore the effects of drugs that interfere with these metabolic processes were studied to establish possible differences in the regulation of the glutathione metabolism of a chloroquine-sensitive and a chloroquine-resistant strain of Plasmodium falciparum. Growth inhibition of P. falciparum 3D7 by D,L-buthionine-( S, R )sulphoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase (gamma-GCS), and by Methylene Blue (MB), an inhibitor of gluta thione reductase (GR), was significantly more pronounced than inhibition of P. falciparum Dd2 growth by these drugs. These results correlate with the higher levels of total glutathione in P. falciparum Dd2. Short-term incubations of Percoll-enriched trophozoite-infected red blood cells in the presence of BSO, MB and N, N (1)-bis(2-chloroethyl)- N -nitrosourea and subsequent determinations of gamma-GCS activities, GR activities and glutathione disulphide efflux revealed that maintenance of intracellular glutathione in P. falciparum Dd2 is mainly dependent on glutathione synthesis whereas in P. falciparum 3D7 it is regulated via GR. Generally, P. falciparum Dd2 appears to be able to sustain its intracellular glutathione more efficiently than P. falciparum 3D7. In agreement with these findings is the differential susceptibility to oxidative stress of both parasite strains elicited by the glucose/glucose oxidase system.
Collapse
|
36
|
Kanzok SM, Rahlfs S, Becker K, Schirmer RH. Thioredoxin, thioredoxin reductase, and thioredoxin peroxidase of malaria parasite Plasmodium falciparum. Methods Enzymol 2002; 347:370-81. [PMID: 11898428 DOI: 10.1016/s0076-6879(02)47037-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Stefan M Kanzok
- Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
| | | | | | | |
Collapse
|
37
|
Shenai BR, Rosenthal PJ. Reducing requirements for hemoglobin hydrolysis by Plasmodium falciparum cysteine proteases. Mol Biochem Parasitol 2002; 122:99-104. [PMID: 12076775 DOI: 10.1016/s0166-6851(02)00075-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Bhaskar R Shenai
- Department of Medicine, San Francisco General Hospital, Box 0811 University of California, San Francisco, CA 94143-0811, USA
| | | |
Collapse
|
38
|
Savvides SN, Scheiwein M, Bohme CC, Arteel GE, Karplus PA, Becker K, Schirmer RH. Crystal structure of the antioxidant enzyme glutathione reductase inactivated by peroxynitrite. J Biol Chem 2002; 277:2779-84. [PMID: 11705998 DOI: 10.1074/jbc.m108190200] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
As part of our studies on the nitric oxide-related pathology of cerebral malaria, we show that the antioxidative enzyme glutathione reductase (GR) is inactivated by peroxynitrite, with GR from the malarial parasite Plasmodium falciparum being more sensitive than human GR. The crystal structure of modified human GR at 1.9-A resolution provides the first picture of protein inactivation by peroxynitrite and reveals that this is due to the exclusive nitration of 2 Tyr residues (residues 106 and 114) at the glutathione disulfide-binding site. The selective nitration explains the impairment of binding the peptide substrate and thus the nearly 1000-fold decrease in catalytic efficiency (k(cat)/K(m)) of glutathione reductase observed at physiologic pH. By oxidizing the catalytic dithiol to a disulfide, peroxynitrite itself can act as a substrate of unmodified and bisnitrated P. falciparum glutathione reductase.
Collapse
Affiliation(s)
- Savvas N Savvides
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Rahlfs S, Fischer M, Becker K. Plasmodium falciparum possesses a classical glutaredoxin and a second, glutaredoxin-like protein with a PICOT homology domain. J Biol Chem 2001; 276:37133-40. [PMID: 11479312 DOI: 10.1074/jbc.m105524200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The genes coding for two different proteins with homologies to glutaredoxins have been identified in the genome of the malarial parasite Plasmodium falciparum. Both genes were amplified from a gametocytic cDNA and overexpressed in Escherichia coli. The smaller protein (named PfGrx-1) with 12.4 kDa in size exhibits the typical glutaredoxin active site motif "CPYC," shows glutathione-dependent glutaredoxin activity in the beta-hydroxyethyl disulfide (HEDS) assay, and reduces Trypanosoma brucei ribonucleotide reductase. Glutathione:HEDS transhydrogenase activity (approximately 60 milliunits/mg of protein) was clearly detectable in trophozoite extracts from eight different P. falciparum strains and did not differ between chloroquine-resistant and -sensitive parasites. Five different antimalarial drugs at 100 microm did not significantly influence isolated PfGrx-1 activity. In contrast, the second protein (deduced mass 19.9 kDa) with homology to glutaredoxins (31% identity to Schizosaccharomyces pombe in a 140-amino acid overlap) was not active in the HEDS assay; however, its general dithiol reducing activity was demonstrated in the insulin assay in the presence of dithiothreitol. Interestingly, the sequence contains a PICOT (for protein kinase C-interacting cousin of thioredoxin) homology domain, which might suggest regulatory functions of the protein. We named this protein PfGLP-1, for P. falciparum 1-Cys-glutaredoxin-like protein-1. In contrast to glutaredoxins, PfGLP-1 could not be reduced by glutathione. This is the first report on glutaredoxin-like proteins in the family of Plasmodia.
Collapse
Affiliation(s)
- S Rahlfs
- Interdisciplinary Research Center, Justus Liebig University, 35392 Giessen, Germany
| | | | | |
Collapse
|
40
|
Kanzok SM, Schirmer RH, Turbachova I, Iozef R, Becker K. The thioredoxin system of the malaria parasite Plasmodium falciparum. Glutathione reduction revisited. J Biol Chem 2000; 275:40180-6. [PMID: 11013257 DOI: 10.1074/jbc.m007633200] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In most living cells, redox homeostasis is based both on the glutathione and the thioredoxin system. In the malaria parasite Plasmodium falciparum antioxidative proteins represent promising targets for the development of antiparasitic drugs. We cloned and expressed a thioredoxin of P. falciparum (pftrx), and we improved the stable expression of the thioredoxin reductase (PfTrxR) of the parasite by multiple silent mutagenesis. Both proteins were biochemically characterized and compared with the human host thioredoxin system. Intriguingly, the 13-kDa protein PfTrx is a better substrate for human TrxR (K(m) = 2 microm, k(cat) = 3300 min(-)(1)) than for P. falciparum TrxR (K(m) = 10.4 microm, k(cat) = 3100 min(-)(1)). Possessing a midpoint potential of -270 mV, PfTrx was found to reduce the disease-related metabolites S-nitrosoglutathione and GSSG. The rate constant k(2) for the reaction between reduced P. falciparum thioredoxin and GSSG was determined to be 0.039 microm(-)(1) min(-)(1) at 25 degrees C and pH 7.4. The k(2) for thioredoxins from man, Drosophila melanogaster, and Escherichia coli was approximately 5 times lower. Our data suggest that GSSG reduction can be supported at a high rate by the TrxR/Trx system in glutathione reductase-deficient cells; this may be relevant for certain stages of the malarial parasite but also for cells containing high [GSSG] of other organisms like dormant forms of Neurospora, glutathione reductase-deficient yeast mutants, or CD4(+) lymphocytes of AIDS patients.
Collapse
Affiliation(s)
- S M Kanzok
- Center of Biochemistry, Heidelberg University, D-69120 Heidelberg, Research Center for Infectious Diseases, Würzburg University, D-97070 Würzburg, Germany
| | | | | | | | | |
Collapse
|
41
|
Bohme CC, Arscott LD, Becker K, Schirmer RH, Williams CH. Kinetic characterization of glutathione reductase from the malarial parasite Plasmodium falciparum. Comparison with the human enzyme. J Biol Chem 2000; 275:37317-23. [PMID: 10969088 DOI: 10.1074/jbc.m007695200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The homodimeric flavoenzyme glutathione reductase (GR) maintains high intracellular concentrations of the antioxidant glutathione (GSSG + NADPH + H(+) <--> 2 GSH + NADP(+)). Due to its central function in cellular redox metabolism, inhibition of GR from the malarial parasite Plasmodium falciparum represents an important approach to antimalarial drug development; therefore, the catalytic mechanism of GR from P. falciparum has been analyzed and compared with the human host enzyme. The reductive half-reaction is similar to the analogous reaction with GR from other species. The oxidative half-reaction is biphasic, reflecting formation and breakdown of a mixed disulfide between the interchange thiol and GSH. The equilibrium between the E(ox)-EH(2) and GSSG-GSH couples has been modeled showing that the Michaelis complex, mixed disulfide-GSH, is the predominant enzyme form as the oxidative half-reaction progresses; rate constants used in modeling allow calculation of an K(eq) from the Haldane relationship, 0.075, very similar to the K(eq) of the same reaction for the yeast enzyme (0.085) (Arscott, L. D., Veine, D. M., and Williams, C. H., Jr. (2000) Biochemistry 39, 4711-4721). Enzyme-monitored turnover indicates that E(FADH(-))(S-S). NADP(+) and E(FAD)(SH)(2).NADPH are dominant enzyme species in turnover. Since the individual forms of the enzyme differ in their susceptibility to inhibitors, the prevailing states of GR in the cell are of practical relevance.
Collapse
Affiliation(s)
- C C Bohme
- Department of Veterans Affairs Medical Center, Ann Arbor, Michigan 48105, Center of Biochemistry, Heidelberg University, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | | | | | | | | |
Collapse
|
42
|
Abstract
The need for new antimalarials comes from the widespread resistance to those in current use. New antimalarial targets are required to allow the discovery of chemically diverse, effective drugs. The search for such new targets and new drug chemotypes will likely be helped by the advent of functional genomics and structure-based drug design. After validation of the putative targets as those capable of providing effective and safe drugs, targets can be used as the basis for screening compounds in order to identify new leads, which, in turn, will qualify for lead optimization work. The combined use of combinatorial chemistry--to generate large numbers of structurally diverse compounds--and of high throughput screening systems--to speed up the testing of compounds--hopefully will help to optimize the process. Potential chemotherapeutic targets in the malaria parasite can be broadly classified into three categories: those involved in processes occurring in the digestive vacuole, enzymes involved in macromolecular and metabolite synthesis, and those responsible for membrane processes and signalling. The processes occurring in the digestive vacuole include haemoglobin digestion, redox processes and free radical formation, and reactions accompanying haem release followed by its polymerization into haemozoin. Many enzymes in macromolecular and metabolite synthesis are promising potential targets, some of which have been established in other microorganisms, although not yet validated for Plasmodium, with very few exceptions (such as dihydrofolate reductase). Proteins responsible for membrane processes, including trafficking and drug transport and signalling, are potentially important also to identify compounds to be used in combination with antimalarial drugs to combat resistance.
Collapse
Affiliation(s)
- P L Olliaro
- UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, Geneva, Switzerland
| | | |
Collapse
|
43
|
Lang-Unnasch N, Murphy AD. Metabolic changes of the malaria parasite during the transition from the human to the mosquito host. Annu Rev Microbiol 1999; 52:561-90. [PMID: 9891808 DOI: 10.1146/annurev.micro.52.1.561] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plasmodium falciparum is an obligate human parasite that is the causative agent of the most lethal form of human malaria. Transmission of P. falciparum to a new human host requires a mosquito vector within which sexual replication occurs. P. falciparum replicates as an intracellular parasite in man and as an extracellular parasite in the mosquito, and it undergoes multiple developmental changes in both hosts. Changes in the environment and the activities of parasites in these various life-cycle stages are likely to be reflected in changes in the metabolic needs and capabilities of the parasite. Most of our knowledge of the metabolic capabilities of P. falciparum is derived from studies of the asexual erythrocytic cycle of the parasite, the portion of the parasite life cycle found in infected humans that is responsible for malarial symptoms. Efforts to control transmission and to understand the sometimes unique biology of this parasite have led to information about the metabolic capabilities of sexual and/or sporogonic stages of these parasites. This review focuses on comparing and contrasting the carbohydrate, nucleic acid, and protein synthetic capabilities of asexual erythrocytic stages and sexual stages of P. falciparum.
Collapse
Affiliation(s)
- N Lang-Unnasch
- Department of Medicine, University of Alabama at Birmingham 35294-2170, USA.
| | | |
Collapse
|
44
|
Lüersen K, Walter RD, Müller S. The putative gamma-glutamylcysteine synthetase from Plasmodium falciparum contains large insertions and a variable tandem repeat. Mol Biochem Parasitol 1999; 98:131-42. [PMID: 10029315 DOI: 10.1016/s0166-6851(98)00161-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The tripeptide glutathione plays a pivotal role in the maintenance of the thiol redox state of the cell and for the detoxification of reactive oxygen species. Glutathione is synthesized in two consecutive reactions by y-glutamylcysteine synthetase (gamma-GCS) and glutathione synthetase, respectively. The former enzyme represents the rate limiting step of the synthetic pathway. We have cloned the cDNA and gene of a putative gamma-GCS from Plasmodium falciparum. The contiguous cDNA sequences obtained from various cDNA libraries of P. falciparum K1 and 3D7 encompass 4206 bp or 4038 bp and encode polypeptides of 1119 and 1063 amino acids, respectively. The deduced amino acid sequences show four regions of homology (identity: 31.3-43.9%) to human and Trypanosoma brucei gamma-GCS. These regions are interrupted by three large insertions between 94 and 239 amino acids. Within the first insert a variable repetitive motif was identified, which is responsible for the differing sizes of the sequences. We have analysed this phenomenon in five additional P. falciparum strains and found a high degree of variability in the number of the repeated octamer (Y/C)S(N/D)LQQ(Q/R). Therefore the predicted molecular mass of the proteins from different P. falciparum strains ranges from 124.4 to 133.2 kDa, which is almost twice that of the catalytic subunit of the human host enzyme. Isolation of three genomic clones revealed that the gene does not contain introns. P. falciparum gamma-GCS transcription peaks in trophozoites (24-30 h) suggesting that the antioxidant glutathione is predominantly produced at a time where hemoglobin degradation and the simultaneous formation of reactive oxygen species is maximal.
Collapse
Affiliation(s)
- K Lüersen
- Bernhard Nocht Institute for Tropical Medicine, Biochemical Parasitology, Hamburg, Germany
| | | | | |
Collapse
|
45
|
Ayi K, Cappadoro M, Branca M, Turrini F, Arese P. Plasmodium falciparum glutathione metabolism and growth are independent of glutathione system of host erythrocyte. FEBS Lett 1998; 424:257-61. [PMID: 9539162 DOI: 10.1016/s0014-5793(98)00185-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Plasmodium falciparum parasites grew normally in glutathione (GSH)-depleted normal and G6PD-deficient (Mediterranean variant) erythrocytes (RBC). Growth inhibition was observed only at less than approximately 6-12% residual GSH. Parasites studied separately with the Sendai virus technique synthesized GSH de novo and regenerated reduced GSH 10-20 times faster than non-parasitized RBC. Electron spin resonance measurement of Tempol reduction indicated that the ability to reduce free radicals was restricted to the parasite. The marked efflux of oxidized GSH was mainly derived from the parasite. In conclusion, parasites are endowed with powerful and host-independent mechanisms which de novo synthesize or regenerate GSH and allow undisturbed parasite development in GSH-depleted RBC.
Collapse
Affiliation(s)
- K Ayi
- Dipartimento di Genetica, Biologia e Biochimica, Università di Torino, Turin, Italy
| | | | | | | | | |
Collapse
|
46
|
Färber PM, Arscott LD, Williams CH, Becker K, Schirmer RH. Recombinant Plasmodium falciparum glutathione reductase is inhibited by the antimalarial dye methylene blue. FEBS Lett 1998; 422:311-4. [PMID: 9498806 DOI: 10.1016/s0014-5793(98)00031-3] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Plasmodium falciparum glutathione reductase (PfGR) has emerged as a drug target against tropical malaria. Here we report the expression of PfGR in Escherichia coli SG5(DE3) and isolation procedures for this protein. Recombinant PfGR does not differ from the authentic enzyme in its enzymic properties, the turnover number being 9900 min(-1). The dimeric flavoenzyme exhibits redox-dependent absorption spectra; the single tryptophan residue (per 57.2 kDa subunit) is strongly fluorescent. PfGR can be inhibited by the antimalarial drug methylene blue at therapeutic concentrations; the Ki for non-competitive inhibition is 6.4 microM. The sensitivity to methylene blue is observed also at high ionic strength so that, by analogy to human GR, analysis of crystalline enzyme-drug complexes can be envisaged.
Collapse
Affiliation(s)
- P M Färber
- Biochemie-Zentrum der Universität Heidelberg, Germany.
| | | | | | | | | |
Collapse
|
47
|
Atamna H, Ginsburg H. The malaria parasite supplies glutathione to its host cell--investigation of glutathione transport and metabolism in human erythrocytes infected with Plasmodium falciparum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 250:670-9. [PMID: 9461289 DOI: 10.1111/j.1432-1033.1997.00670.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Malaria-infected red blood cells are under a substantial oxidative stress. Glutathione metabolism may play an important role in antioxidant defense in these cells, as it does in other eukaryotes. In this work, we have determined the levels of reduced and oxidized glutathione (GSH and GSSG, respectively) and their distributions in the parasite, and in the host-cell compartments of human erythrocytes infected with the malaria parasite Plasmodium falciparum. In intact trophozoite-infected erythrocytes, [GSH] is low and [GSSG] is high, compared with the levels in normal erythrocytes. Normal erythrocytes and the parasite compartment display high GSH/GSSG ratios of 321.6 and 284.5, respectively, indicating adequate antioxidant defense. This ratio drops to 26.7 in the host-cell compartment, indicating a forceful oxidant challenge, the low ratios resulting from an increase in GSSG and a decline in GSH concentrations. On the other hand, the concentrations of GSH and GSSG in the parasite compartment remain physiological and comparable to their concentrations in normal red blood cells. This results from de novo glutathione synthesis and its recycling, assisted by the intensive activity of the hexose monophosphate shunt in the parasite. A large efflux of GSSG from infected cells has been observed, its rate being similar from free parasites and from intact infected cells. This result suggests that de novo synthesis by the parasite is the dominating process in infected cells. GSSG efflux from the intact infected cell is more than 60-fold higher than the rate observed in normal erythrocytes, and is mediated by permeability pathways that the parasite induces in the erythrocyte's membrane. The main route for GSSG efflux through the cytoplasmic membrane of the parasite seems to be due to a specific transport system and occurs against a concentration gradient. Gamma-glutamylcysteine [Glu(-Cys)] and GSH can penetrate through the pathways from the extracellular space into the host cytosol, but not into that of the parasite. This implies that the parasite membrane is impermeable to these peptides, and that the host cannot supply GSH to the parasite as suggested previously. Exogenous Glu(-Cys) is not converted into GSH in the host cell, arguing that GSH synthetase may not be functional. Compartment analysis of Mg2+ in infected erythrocytes revealed that the host compartment exhibits a low concentration of Mg2+ (0.5 mM) in comparison with the parasite compartment (4 mM) and the normal erythrocytes (1.5-3 mM). The drop in [Mg2+] results in cessation of Glu(-Cys) synthesis, and hence of GSH synthesis in the host-cell compartment. The decrease in [Mg2+] can affect other Mg2+-ATP-dependent functions, such as Na+ and Ca2+ active efflux. The present investigation confirms that the host-cell compartment is oxidatively distressed, whereas the parasite is efficiently equipped with anti-oxidant means that protect the parasite from the oxidative injury. The parasite has a huge capacity for de novo synthesis of GSH and for the reduction of GSSG. Part of the GSSG that is actively extruded from the parasite is reduced to GSH in the host cell whose own GSH synthesis is crippled.
Collapse
Affiliation(s)
- H Atamna
- Department of Biological Chemistry, Institute of Life Sciences, Hebrew University, Jerusalem, Israel
| | | |
Collapse
|
48
|
Färber PM, Becker K, Müller S, Schirmer RH, Franklin RM. Molecular cloning and characterization of a putative glutathione reductase gene, the PfGR2 gene, from Plasmodium falciparum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 239:655-61. [PMID: 8774709 DOI: 10.1111/j.1432-1033.1996.0655u.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recently, glutathione reductase (GR) has emerged as a promising target for antiparasitic drugs. The central role of GR in cellular antioxidant defence, the particular susceptibility of intracellular parasites like Plasmodium falciparum to oxidative stress, and successful inhibitor studies substantiate this approach. However, more information is required on the structural and functional characteristics of GR from malarial parasites and differences from the enzyme of host erythrocytes. We have identified a putative P. falciparum GR gene coding for a polypeptide (PfGR2) of 500 amino acids that exhibits 40-45% sequence identity with GR enzymes from other species. 18 out of 19 residues contributing to glutathione binding are identical in the putative PfGR2 and human GR. According to Southern blot analysis, the PfGR2 gene is present as a single-copy gene. It is expressed during the intraerythrocytic life cycle. Stage-specific Northern blot analysis demonstrates that the PfGR2 gene is only weakly transcribed in ring, early trophozoite, and segmenter stages; major transcription occurs in the late trophozoite/early schizont stage. This is consistent with the high glutathione reductase activity found in early schizonts. Other data also suggest that PfGR2 corresponds to the enzyme isolated from parasitized erythrocytes. These criteria include the subunit molecular mass (56.2 kDa), the N-terminal sequence (VYDLIVIGGGSGGMA), the presence of specific sequence motifs at ligand-binding sites, and, as demonstrated by Western blotting, the occurrence of a unique chain segment in the core of the central domain. In view of these data, the function(s) of PfGR2 as well as PfGR1, the product of another GR-like gene of P. falciparum (Müller et al., 1995) should be carefully assessed.
Collapse
Affiliation(s)
- P M Färber
- Biozentrum der Universität Basel, Switzerland
| | | | | | | | | |
Collapse
|