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DeMichele E, Sosnowski O, Buret AG, Allain T. Regulatory Functions of Hypoxia in Host-Parasite Interactions: A Focus on Enteric, Tissue, and Blood Protozoa. Microorganisms 2023; 11:1598. [PMID: 37375100 PMCID: PMC10303274 DOI: 10.3390/microorganisms11061598] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
Body tissues are subjected to various oxygenic gradients and fluctuations and hence can become transiently hypoxic. Hypoxia-inducible factor (HIF) is the master transcriptional regulator of the cellular hypoxic response and is capable of modulating cellular metabolism, immune responses, epithelial barrier integrity, and local microbiota. Recent reports have characterized the hypoxic response to various infections. However, little is known about the role of HIF activation in the context of protozoan parasitic infections. Growing evidence suggests that tissue and blood protozoa can activate HIF and subsequent HIF target genes in the host, helping or hindering their pathogenicity. In the gut, enteric protozoa are adapted to steep longitudinal and radial oxygen gradients to complete their life cycle, yet the role of HIF during these protozoan infections remains unclear. This review focuses on the hypoxic response to protozoa and its role in the pathophysiology of parasitic infections. We also discuss how hypoxia modulates host immune responses in the context of protozoan infections.
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Affiliation(s)
- Emily DeMichele
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Olivia Sosnowski
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Andre G. Buret
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Thibault Allain
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada; (E.D.); (O.S.); (A.G.B.)
- Inflammation Research Network, University of Calgary, Calgary, AB T2N 1N4, Canada
- Host-Parasite Interactions, University of Calgary, Calgary, AB T2N 1N4, Canada
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Sussmann RAC, Gabriel HB, Ríos AG, Menchaca Vega DS, Yamaguchi LF, Doménech-Carbó A, Cebrián-Torrejón G, Kimura EA, Kato MJ, Bofill Verdaguer I, Crispim M, Katzin AM. Presence of Phylloquinone in the Intraerythrocytic Stages of Plasmodium falciparum. Front Cell Infect Microbiol 2022; 12:869085. [PMID: 35531326 PMCID: PMC9069557 DOI: 10.3389/fcimb.2022.869085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Malaria is one of the most widespread parasitic diseases, especially in Africa, Southeast Asia and South America. One of the greatest problems for control of the disease is the emergence of drug resistance, which leads to a need for the development of new antimalarial compounds. The biosynthesis of isoprenoids has been investigated as part of a strategy to identify new targets to obtain new antimalarial drugs. Several isoprenoid quinones, including menaquinone-4 (MK-4/vitamin K2), α- and γ-tocopherol and ubiquinone (UQ) homologs UQ-8 and UQ-9, were previously detected in in vitro cultures of Plasmodium falciparum in asexual stages. Herein, we described for the first time the presence of phylloquinone (PK/vitamin K1) in P. falciparum and discuss the possible origins of this prenylquinone. While our results in metabolic labeling experiments suggest a biosynthesis of PK prenylation via phytyl pyrophosphate (phytyl-PP) with phytol being phosphorylated, on the other hand, exogenous PK attenuated atovaquone effects on parasitic growth and respiration, showing that this metabolite can be transported from extracellular environment and that the mitochondrial electron transport system (ETS) of P. falciparum is capable to interact with PK. Although the natural role and origin of PK remains elusive, this work highlights the PK importance in plasmodial metabolism and future studies will be important to elucidate in seeking new targets for antimalarial drugs.
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Affiliation(s)
- Rodrigo A. C. Sussmann
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Center for Environmental Sciences, Institute of Humanities, Arts and Sciences, Federal University of Southern Bahia, Porto Seguro, Brazil
| | - Heloisa B. Gabriel
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Alejandro García Ríos
- Laboratory of Environmental Chemistry and Metalopharmaceuticals, Institute of Chemistry at the University of São Paulo, São Paulo, Brazil
- Chemistry Program, Universidad del Quindio, Quindio, Colombia
| | - Danielle S. Menchaca Vega
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Lydia F. Yamaguchi
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Antonio Doménech-Carbó
- Departament of Analytic Chemistry, Facultat de Química, Universitat de València, Valencia, Spain
| | - Gerardo Cebrián-Torrejón
- Laboratoire Connaissance et Valorisation Equipes d'Accueil (COVACHIM-M2E EA) 3592, Université des Antilles, Pointe-à-Pitre Cedex, Pointe-à-Pitre, Guadeloupe, France
| | - Emilia A. Kimura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Massuo J. Kato
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Ignasi Bofill Verdaguer
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marcell Crispim
- 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
- *Correspondence: Alejandro M. Katzin,
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Exploring Ubiquinone Biosynthesis Inhibition as a Strategy for Improving Atovaquone Efficacy in Malaria. Antimicrob Agents Chemother 2021; 65:AAC.01516-20. [PMID: 33495230 DOI: 10.1128/aac.01516-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/16/2021] [Indexed: 11/20/2022] Open
Abstract
Atovaquone (AV) acts on the malaria parasite by competing with ubiquinol (UQH2) for its union to the mitochondrial bc1 complex, preventing the ubiquinone-8 and ubiquinone-9 (UQ-8 and UQ-9) redox recycling, which is a necessary step in pyrimidine biosynthesis. This study focused on UQ biosynthesis in Plasmodium falciparum and adopted proof-of-concept research to better elucidate the mechanism of action of AV and improve its efficacy. Initially, UQ biosynthesis was evaluated using several radioactive precursors and chromatographic techniques. This methodology was suitable for studying the biosynthesis of both UQ homologs and its redox state. Additionally, the composition of UQ was investigated in parasites cultivated at different oxygen saturations or in the presence of AV. AV affected the redox states of both UQ-8 and UQ-9 homologs by increasing the levels of the respective reduced forms. Conversely, low-oxygen environments specifically inhibited UQ-9 biosynthesis and increased the antimalarial efficacy of AV. These findings encouraged us to investigate the biological importance and the potential of UQ biosynthesis as a drug target based on its inhibition by 4-nitrobenzoate (4-NB), a 4-hydroxybenzoate (4-HB) analog. 4-NB effectively inhibits UQ biosynthesis and enhances the effects of AV on parasitic growth and respiration rate. Although 4-NB itself exhibits poor antimalarial activity, its 50% inhibitory concentration (IC50) value increased significantly in the presence of a soluble UQ analog, p-aminobenzoic acid (pABA), or 4-HB. These results indicate the potential of AV combined with 4-NB as a novel therapy for malaria and other diseases caused by AV-sensitive pathogens.
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Scarpelli PH, Tessarin‐Almeida G, Viçoso KL, Lima WR, Borges‐Pereira L, Meissner KA, Wrenger C, Rafaello A, Rizzuto R, Pozzan T, Garcia CRS. Melatonin activates FIS1, DYN1, and DYN2 Plasmodium falciparum related-genes for mitochondria fission: Mitoemerald-GFP as a tool to visualize mitochondria structure. J Pineal Res 2019; 66:e12484. [PMID: 29480948 PMCID: PMC6585791 DOI: 10.1111/jpi.12484] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 02/01/2018] [Indexed: 02/06/2023]
Abstract
Malaria causes millions of deaths worldwide and is considered a huge burden to underdeveloped countries. The number of cases with resistance to all antimalarials is continuously increasing, making the identification of novel drugs a very urgent necessity. A potentially very interesting target for novel therapeutic intervention is the parasite mitochondrion. In this work, we studied in Plasmodium falciparum 3 genes coding for proteins homologues of the mammalian FIS1 (Mitochondrial Fission Protein 1) and DRP1 (Dynamin Related Protein 1) involved in mitochondrial fission. We studied the expression of P. falciparum genes that show ample sequence and structural homologies with the mammalian counterparts, namely FIS1, DYN1, and DYN2. The encoded proteins are characterized by a distinct pattern of expression throughout the erythrocytic cycle of P. falciparum, and their mRNAs are modulated by treating the parasite with the host hormone melatonin. We have previously reported that the knockout of the Plasmodium gene that codes for protein kinase 7 is essential for melatonin sensing. We here show that PfPk7 knockout results in major alterations of mitochondrial fission genes expression when compared to wild-type parasites, and no change in fission proteins expression upon treatment with the host hormone. Finally, we have compared the morphological characteristics (using MitoTracker Red CMX Ros) and oxygen consumption properties of P. falciparum mitochondria in wild-type parasites and PfPk7 Knockout strains. A novel GFP construct targeted to the mitochondrial matrix to wild-type parasites was also developed to visualize P. falciparum mitochondria. We here show that, the functional characteristics of P. falciparum are profoundly altered in cells lacking protein kinase 7, suggesting that this enzyme plays a major role in the control of mitochondrial morphogenesis and maturation during the intra-erythrocyte cell cycle progression.
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Affiliation(s)
- Pedro H. Scarpelli
- Departamento de ParasitologiaInstituto de Ciências BiomédicasUniversidade de São PauloSão PauloBrazil
- Departamento de FisiologiaInstituto de BiociênciasUniversidade de São PauloSão PauloBrazil
| | | | - Kênia Lopes Viçoso
- Departamento de FisiologiaInstituto de BiociênciasUniversidade de São PauloSão PauloBrazil
| | - Wania Rezende Lima
- Instituto de Ciências Exatas e Naturais‐MedicinaUniversidade Federal de Mato Grosso‐Campus RondonópolisMato GrossoBrazil
| | - Lucas Borges‐Pereira
- Departamento de FisiologiaInstituto de BiociênciasUniversidade de São PauloSão PauloBrazil
| | - Kamila Anna Meissner
- Departamento de ParasitologiaInstituto de Ciências BiomédicasUniversidade de São PauloSão PauloBrazil
| | - Carsten Wrenger
- Departamento de ParasitologiaInstituto de Ciências BiomédicasUniversidade de São PauloSão PauloBrazil
| | - Anna Rafaello
- CNR Neurosciences InstituteUniversity of PadovaPadovaItaly
| | | | - Tullio Pozzan
- CNR Neurosciences InstituteUniversity of PadovaPadovaItaly
| | - Celia R. S. Garcia
- Departamento de FisiologiaInstituto de BiociênciasUniversidade de São PauloSão PauloBrazil
- Departamento de Fisiologia, Instituto de BiociênciasUniversidade de São PauloSão PauloBrazil
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Ebiloma GU, Balogun EO, Cueto-Díaz EJ, de Koning HP, Dardonville C. Alternative oxidase inhibitors: Mitochondrion-targeting as a strategy for new drugs against pathogenic parasites and fungi. Med Res Rev 2019; 39:1553-1602. [PMID: 30693533 DOI: 10.1002/med.21560] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/07/2018] [Accepted: 12/08/2018] [Indexed: 12/11/2022]
Abstract
The alternative oxidase (AOX) is a ubiquitous terminal oxidase of plants and many fungi, catalyzing the four-electron reduction of oxygen to water alongside the cytochrome-based electron transfer chain. Unlike the classical electron transfer chain, however, the activity of AOX does not generate adenosine triphosphate but has functions such as thermogenesis and stress response. As it lacks a mammalian counterpart, it has been investigated intensely in pathogenic fungi. However, it is in African trypanosomes, which lack cytochrome-based respiration in their infective stages, that trypanosome alternative oxidase (TAO) plays the central and essential role in their energy metabolism. TAO was validated as a drug target decades ago and among the first inhibitors to be identified was salicylhydroxamic acid (SHAM), which produced the expected trypanocidal effects, especially when potentiated by coadministration with glycerol to inhibit anaerobic energy metabolism as well. However, the efficacy of this combination was too low to be of practical clinical use. The antibiotic ascofuranone (AF) proved a much stronger TAO inhibitor and was able to cure Trypanosoma vivax infections in mice without glycerol and at much lower doses, providing an important proof of concept milestone. Systematic efforts to improve the SHAM and AF scaffolds, aided with the elucidation of the TAO crystal structure, provided detailed structure-activity relationship information and reinvigorated the drug discovery effort. Recently, the coupling of mitochondrion-targeting lipophilic cations to TAO inhibitors has dramatically improved drug targeting and trypanocidal activity while retaining target protein potency. These developments appear to have finally signposted the way to preclinical development of TAO inhibitors.
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Affiliation(s)
- Godwin U Ebiloma
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto, Japan.,Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Emmanuel O Balogun
- Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria.,Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Sakata-Kato T, Wirth DF. A Novel Methodology for Bioenergetic Analysis of Plasmodium falciparum Reveals a Glucose-Regulated Metabolic Shift and Enables Mode of Action Analyses of Mitochondrial Inhibitors. ACS Infect Dis 2016; 2:903-916. [PMID: 27718558 DOI: 10.1021/acsinfecdis.6b00101] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Given that resistance to all drugs in clinical use has arisen, discovery of new antimalarial drug targets is eagerly anticipated. The Plasmodium mitochondrion has been considered a promising drug target largely based on its significant divergence from the host organelle as well as its involvement in ATP production and pyrimidine biosynthesis. However, the functions of Plasmodium mitochondrial protein complexes and associated metabolic pathways are not fully characterized. Here, we report the development of novel and robust bioenergetic assay protocols for Plasmodium falciparum asexual parasites utilizing a Seahorse Bioscience XFe24 Extracellular Flux Analyzer. These protocols allowed us to simultaneously assess the direct effects of metabolites and inhibitors on mitochondrial respiration and glycolytic activity in real-time with the readout of oxygen consumption rate and extracellular acidification rate. Using saponin-freed parasites at the schizont stage, we found that succinate, malate, glycerol-3-phosphate, and glutamate, but not pyruvate, were able to increase the oxygen consumption rate and that glycerol-3-phosphate dehydrogenase had the largest potential as an electron donor among tested mitochondrial dehydrogenases. Furthermore, we revealed the presence of a glucose-regulated metabolic shift between oxidative phosphorylation and glycolysis. We measured proton leak and reserve capacity and found bioenergetic evidence for oxidative phosphorylation in erythrocytic stage parasites but at a level much lower than that observed in mammalian cells. Lastly, we developed an assay platform for target identification and mode of action studies of mitochondria-targeting antimalarials. This study provides new insights into the bioenergetics and metabolomics of the Plasmodium mitochondria.
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Affiliation(s)
- Tomoyo Sakata-Kato
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, United States
| | - Dyann F. Wirth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, United States
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Fang X, Reifman J, Wallqvist A. Modeling metabolism and stage-specific growth of Plasmodium falciparum HB3 during the intraerythrocytic developmental cycle. MOLECULAR BIOSYSTEMS 2015; 10:2526-37. [PMID: 25001103 DOI: 10.1039/c4mb00115j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The human malaria parasite Plasmodium falciparum goes through a complex life cycle, including a roughly 48-hour-long intraerythrocytic developmental cycle (IDC) in human red blood cells. A better understanding of the metabolic processes required during the asexual blood-stage reproduction will enhance our basic knowledge of P. falciparum and help identify critical metabolic reactions and pathways associated with blood-stage malaria. We developed a metabolic network model that mechanistically links time-dependent gene expression, metabolism, and stage-specific growth, allowing us to predict the metabolic fluxes, the biomass production rates, and the timing of production of the different biomass components during the IDC. We predicted time- and stage-specific production of precursors and macromolecules for P. falciparum (strain HB3), allowing us to link specific metabolites to specific physiological functions. For example, we hypothesized that coenzyme A might be involved in late-IDC DNA replication and cell division. Moreover, the predicted ATP metabolism indicated that energy was mainly produced from glycolysis and utilized for non-metabolic processes. Finally, we used the model to classify the entire tricarboxylic acid cycle into segments, each with a distinct function, such as superoxide detoxification, glutamate/glutamine processing, and metabolism of fumarate as a byproduct of purine biosynthesis. By capturing the normal metabolic and growth progression in P. falciparum during the IDC, our model provides a starting point for further elucidation of strain-specific metabolic activity, host-parasite interactions, stress-induced metabolic responses, and metabolic responses to antimalarial drugs and drug candidates.
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Affiliation(s)
- Xin Fang
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, USA.
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Abstract
Philasterides dicentrarchi causes a severe disease in turbot, and at present there are no drugs available to treat infected fish. We have previously demonstrated that, in addition to the classical respiratory pathway, P. dicentrarchi possesses an alternative mitochondrial respiratory pathway that is cyanide-insensitive and salicylhydroxamic acid (SHAM)-sensitive. In this study, we found that during the initial phase of growth in normoxia, ciliate respiration is sensitive to the natural polyphenol resveratrol (RESV) and to Antimycin A (AMA). However, under hypoxic conditions, the parasite utilizes AMA-insensitive respiration, which is completely inhibited by RESV and by the antioxidant propyl gallate (PG), an alternative oxidase (AOX) inhibitor. PG caused significantly dose-dependent inhibition of the in vitro growth of the parasite under normoxia and hypoxia and an over-expression of heat shock proteins of the Hsp70 subfamily. RESV and PG may affect the protective role of the AOX against mitochondrial oxidative stress, leading to an impaired mitochondrial membrane potential and mitochondrial dysfunction, which the parasite attempts to neutralize by increasing the expression of Hsp70. In view of the antiparasitic effects induced by AOX inhibitors and the absence of AOX in their host, this enzyme constitutes a potential target for the development of new drugs against scuticociliatosis.
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Elsheikha HM, McKinlay CL, Elsaied NA, Smith PA. Effects of Neospora caninum infection on brain microvascular endothelial cells bioenergetics. Parasit Vectors 2013; 6:24. [PMID: 23351811 PMCID: PMC3586355 DOI: 10.1186/1756-3305-6-24] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/19/2013] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The brain is the most commonly affected organ during Neospora caninum infection but the mechanisms utilized by this protozoan parasite for traversal of the blood-brain barrier (BBB) are not yet understood. Herein, we investigate the cellular pathogenicity of N. caninum infection on bioenergetics of human brain microvascular endothelial cells (HBMECs), a fundamental component of the BBB. METHODS We tracked the growth kinetics of N. caninum in HBMECs. Focusing on cell bioenergetics, oxygen consumption rate (OCR) was determined using Clark electrode system and mitochondrial membrane potential (ΔΨm) was evaluated using DePsipher staining by fluorescence microscopy in the presence and absence of infection. RESULTS HBMECs provided a receptive environment for parasite proliferation. N. caninum tachyzoites were able to invade and replicate within HBMECs without significantly altering cell proliferation rate, as measured with the MTT assay, up to 24 hr post infection (pi). The oxygen consumption rate (OCR) was significantly inhibited (p < 0.001) by 10 mM glucose [from -2.26±0.23 to -0.6±0.21 nmol 106 cell min-1 and from -0.29±0.09 to -0.16±0.1 nmol 106 cell min-1 for uninfected HBMECs and free N. Caninum tachyzoites, respectively]. After normalization for DNA content the basal OCR did not differ between two host cell types: HBMECs and K562. The OCR of HBMECs was significantly elevated 24 hr pi in the absence of substrate, in 10 mM glucose and in the presence of a tetramethyl-p-phenylenediamine (TMPD)/ascorbate redox shuttle. Although quantitatively similar results were observed for uninfected K562 cells, there was no effect on their OCR 24 hr pi with N. caninum under any of the above substrate conditions. 6mM azide abolished OCR in all situations. Mitochondrial staining with DePsipher indicated no change in their membrane potential (Δψm) up to 24 hr pi. CONCLUSIONS N. caninum is able to grow in HBMECs without markedly disrupting their normal proliferation or mitochondrial integrity. However, it is associated with an increase in infected cell respiration. Whether this increase reflects numeric addition of the parasites own respiration or results from an additional energy demand upon the host cell remains to be elucidated.
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Affiliation(s)
- Hany M Elsheikha
- School of Veterinary Medicine and Science, Faculty of Medicine and Health Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD, UK.
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Yeo TW, Lampah DA, Kenangalem E, Tjitra E, Price RN, Anstey NM. Impaired skeletal muscle microvascular function and increased skeletal muscle oxygen consumption in severe falciparum malaria. J Infect Dis 2012; 207:528-36. [PMID: 23162136 DOI: 10.1093/infdis/jis692] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Organ dysfunction and tissue hypoxia in severe falciparum malaria result from an imbalance between oxygen delivery and demand. In severe malaria, microvascular obstruction from parasite sequestration decreases oxygen delivery. However, host microvascular function (defined as the capacity to increase oxygen delivery in response to ischemia) and oxygen consumption have not been assessed. METHODS We used near-infrared resonance spectroscopy to measure thenar muscle microvascular function (StO(2)recov) and oxygen consumption (VO(2)) in 36 adults in Papua, Indonesia, with severe malaria, 33 with moderately severe malaria (MSM), 24 with severe sepsis, and 36 healthy controls. RESULTS In the severe malaria group, the StO(2)recov of 2.7%/second was 16% and 22% lower than that in the MSM group (3.1%/second) and control group (3.5%/second), respectively (P < .001), and comparable to that in the severe sepsis group (2.5%/second). In the severe malaria group, StO(2)recov was inversely correlated with lactate level (r = -0.63; P < .001) and predicted death (area under the receiver operating characteristic curve, 0.71 [95% confidence interval {CI}, .51-.92]), with each percentage decrease associated with an increased odds of mortality (odds ratio, 2.49 [95% CI, 1.05-6.2]). Conversely, VO(2) increased in the severe malaria group by 18%, compared with levels in the control and severe sepsis groups (P < .001), and was associated with parasite biomass (r = 0.49; P = .04). CONCLUSIONS Impaired microvascular function is associated with increased mortality among individuals with severe malaria, while oxygen consumption is increased. Tissue hypoxia may result not only from microvascular obstruction, but also from impaired ability of the microvasculature to match oxygen delivery to increased oxygen demand.
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Affiliation(s)
- Tsin W Yeo
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia.
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Torrentino-Madamet M, Almeras L, Travaillé C, Sinou V, Pophillat M, Belghazi M, Fourquet P, Jammes Y, Parzy D. Proteomic analysis revealed alterations of the Plasmodium falciparum metabolism following salicylhydroxamic acid exposure. Res Rep Trop Med 2011; 2:109-119. [PMID: 30881184 DOI: 10.2147/rrtm.s23127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES Although human respiratory metabolism is characterized by the mitochondrial electron transport chain, some organisms present a "branched respiratory chain." This branched pathway includes both a classical and an alternative respiratory chain. The latter involves an alternative oxidase. Though the Plasmodium falciparum alternative oxidase is not yet identified, a specific inhibitor of this enzyme, salicylhydroxamic acid (SHAM), showed a drug effect on P. falciparum respiratory function using oxygen consumption measurements. The present study aimed to highlight the metabolic pathways that are affected in P. falciparum following SHAM exposure. DESIGN A proteomic approach was used to analyze the P. falciparum proteome and determine the metabolic pathways altered following SHAM treatment. To evaluate the SHAM effect on parasite growth, the phenotypic alterations of P. falciparum after SHAM or/and hyperoxia exposure were observed. RESULTS After SHAM exposure, 26 proteins were significantly deregulated using a fluorescent two dimensional-differential gel electrophoresis. Among these deregulated proteins, some were particularly involved in energetic metabolism. And the combinatory effect of SHAM/hyperoxia seems deleterious for the growth of P. falciparum. CONCLUSION Our results indicated that SHAM appears to activate glycolysis and decrease stress defense systems. These data provide a better understanding of parasite biology.
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Affiliation(s)
| | - Lionel Almeras
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Antenne IRBA de Marseille (IMTSSA, Le Pharo)
| | - Christelle Travaillé
- UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo),
| | - Véronique Sinou
- UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo),
| | - Matthieu Pophillat
- Centre d'Immunologie de Marseille Luminy, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée
| | - Maya Belghazi
- Centre d'Analyse Protéomique de Marseille, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord
| | - Patrick Fourquet
- Centre d'Immunologie de Marseille Luminy, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée
| | - Yves Jammes
- UMR-MD2, Physiologie et Physiopathologie en Conditions d'Oxygénations Extrêmes, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, Marseille, France
| | - Daniel Parzy
- UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo),
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Ribaut C, Reybier K, Reynes O, Launay J, Valentin A, Fabre PL, Nepveu F. Electrochemical impedance spectroscopy to study physiological changes affecting the red blood cell after invasion by malaria parasites. Biosens Bioelectron 2008; 24:2721-5. [PMID: 19167879 DOI: 10.1016/j.bios.2008.12.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/28/2008] [Accepted: 12/03/2008] [Indexed: 11/27/2022]
Abstract
The malaria parasite, Plasmodium falciparum, invades human erythrocytes and induces dramatic changes in the host cell. The idea of this work was to use RBC modified electrode to perform electrochemical impedance spectroscopy (EIS) with the aim of monitoring physiological changes affecting the erythrocyte after invasion by the malaria parasite. Impedance cell-based devices are potentially useful to give insight into cellular behavior and to detect morphological changes. The modelling of impedance plots (Nyquist diagram) in equivalent circuit taking into account the presence of the cellular layer, allowed us pointing out specific events associated with the development of the parasite such as (i) strong changes in the host cell cytoplasm illustrated by changes in the film capacity, (ii) perturbation of the ionic composition of the host cell illustrated by changes in the film resistance, (iii) releasing of reducer (lactic acid or heme) and an enhanced oxygen consumption characterized by changes in the charge transfer resistance and in the Warburg coefficient characteristic of the redox species diffusion. These results show that the RBC-based device may help to analyze strategic events in the malaria parasite development constituting a new tool in antimalarial research.
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Affiliation(s)
- Clotilde Ribaut
- Université de Toulouse, UPS, INP, INSA, Laboratoire pharmacochimie des substances naturelles et pharmacophores redox, 118 route de Narbonne, F-31062 Toulouse cedex 9, France
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13
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Chemaly SM, Chen CT, van Zyl RL. Naturally occurring cobalamins have antimalarial activity. J Inorg Biochem 2007; 101:764-73. [PMID: 17343914 DOI: 10.1016/j.jinorgbio.2007.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 12/14/2006] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
The acquisition of resistance by malaria parasites towards existing antimalarials has necessitated the development of new chemotherapeutic agents. The effect of vitamin B(12) derivatives on the formation of beta-haematin (synthetic haemozoin) was determined under conditions similar to those in the parasitic food vacuole (using chloroquine, a known inhibitor of haemozoin formation for comparison). Adenosylcobalamin (Ado-cbl), methylcobalamin (CH(3)-cbl) and aquocobalamin (H(2)O-cbl) were approximately forty times more effective inhibitors of beta-haematin formation than chloroquine, cyanocobalamin (CN-cbl) was slightly more inhibitory than chloroquine, while dicyanocobinamide had no effect. It is proposed that the cobalamins exert their inhibitory effect on beta-haematin formation by pi-interactions of their corrin ring with the Fe(III)-protoporphyrin ring and by hydrogen-bonding using their 5,6-dimethylbenzimidazole/ribose/sugar side-chain. The antimalarial activity for the cobalamins (Ado-cbl>CH(3)-cbl>H(2)O-cbl>CN-cbl) was found to be less than that for chloroquine or quinine. Ado-cbl, CH(3)-cbl and CN-cbl do not accumulate in the parasite food vacuole by pH trapping, but H(2)O-cbl does. Unlike humans, the malaria parasite has only one enzyme that uses cobalamin as a cofactor, namely methionine synthase, which is important for growth and metabolism. Thus cobalamins in very small amounts are necessary for Plasmodium falciparum growth but in larger amounts they display antimalarial properties.
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Affiliation(s)
- Susan M Chemaly
- Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
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14
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Biagini GA, Viriyavejakul P, O'neill PM, Bray PG, Ward SA. Functional characterization and target validation of alternative complex I of Plasmodium falciparum mitochondria. Antimicrob Agents Chemother 2006; 50:1841-51. [PMID: 16641458 PMCID: PMC1472221 DOI: 10.1128/aac.50.5.1841-1851.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 02/03/2006] [Indexed: 11/20/2022] Open
Abstract
This study reports on the first characterization of the alternative NADH:dehydrogenase (also known as alternative complex I or type II NADH:dehydrogenase) of the human malaria parasite Plasmodium falciparum, known as PfNDH2. PfNDH2 was shown to actively oxidize NADH in the presence of quinone electron acceptors CoQ(1) and decylubiquinone with an apparent K(m) for NADH of approximately 17 and 5 muM, respectively. The inhibitory profile of PfNDH2 revealed that the enzyme activity was insensitive to rotenone, consistent with recent genomic data indicating the absence of the canonical NADH:dehydrogenase enzyme. PfNDH2 activity was sensitive to diphenylene iodonium chloride and diphenyl iodonium chloride, known inhibitors of alternative NADH:dehydrogenases. Spatiotemporal confocal imaging of parasite mitochondria revealed that loss of PfNDH2 function provoked a collapse of mitochondrial transmembrane potential (Psi(m)), leading to parasite death. As with other alternative NADH:dehydrogenases, PfNDH2 lacks transmembrane domains in its protein structure, and therefore, it is proposed that this enzyme is not directly involved in mitochondrial transmembrane proton pumping. Rather, the enzyme provides reducing equivalents for downstream proton-pumping enzyme complexes. As inhibition of PfNDH2 leads to a depolarization of mitochondrial Psi(m), this enzyme is likely to be a critical component of the electron transport chain (ETC). This notion is further supported by proof-of-concept experiments revealing that targeting the ETC's Q-cycle by inhibition of both PfNDH2 and the bc(1) complex is highly synergistic. The potential of targeting PfNDH2 as a chemotherapeutic strategy for drug development is discussed.
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Affiliation(s)
- Giancarlo A Biagini
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, United Kingdom.
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15
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Soranzo N, Bufe B, Sabeti PC, Wilson JF, Weale ME, Marguerie R, Meyerhof W, Goldstein DB. Positive selection on a high-sensitivity allele of the human bitter-taste receptor TAS2R16. Curr Biol 2005; 15:1257-65. [PMID: 16051168 DOI: 10.1016/j.cub.2005.06.042] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 05/31/2005] [Accepted: 06/14/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND During periods of human expansion into new environments, recognition of bitter natural toxins through taste may have conferred an important selective advantage. The G protein-coupled receptor encoded by TAS2R16 mediates response to salicin, amygdalin, and many bitter beta-glucopyranosides. beta-glucopyranosides are ubiquitous in nature, with many having a highly toxic cyanogenic activity. RESULTS We examined evidence for natural selection on the human receptor TAS2R16 by sequencing the entire coding region, as well as part of the 5' and 3' UTRs, in 997 individuals from 60 human populations. We detected signatures of positive selection, indicated by an excess of evolutionarily derived alleles at the nonsynonymous site K172N and two linked sites and significant values of Fay and Wu's H statistics in 19 populations. The estimated age range for the common ancestor of the derived N172 variant is 78,700-791,000 years, placing it in the Middle Pleistocene and before the expansion of early humans out of Africa. Using calcium imaging in cells expressing different receptor variants, we showed that N172 is associated with an increased sensitivity to salicin, arbutin, and five different cyanogenic glycosides. CONCLUSION We have detected a clear signal of positive selection at the bitter-taste receptor gene TAS2R16. We speculate that the increased sensitivity that is shown toward harmful cyanogenic glycosides and conferred by the N172 allele may have driven the signal of selection at an early stage of human evolution.
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Affiliation(s)
- Nicole Soranzo
- Department of Biology, University College London, United Kingdom.
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16
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Castro-Guerrero NA, Krab K, Moreno-Sánchez R. The alternative respiratory pathway of euglena mitochondria. J Bioenerg Biomembr 2005; 36:459-69. [PMID: 15534393 DOI: 10.1023/b:jobb.0000047328.82733.ef] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mitochondria, isolated from heterotrophic Euglena gracilis , have cyanide-resistant alternative oxidase (AOX) in their respiratory chain. Cells cultured under a variety of oxidative stress conditions (exposure to cyanide, cold, or H2O2) increased the AOX capacity in mitochondria and cells, although it was significant only under cold stress; AOX sensitivity to inhibitors was also increased by cold and cyanide stress. The value of AOX maximal activity reached 50% of total respiration below 20 degrees C, whereas AOX full activity was only 10-30% of total respiration above 20 degrees C. The optimum pH for AOX activity was 6.5 and for the cytochrome pathway was 7.3. GMP, AMP, pyruvate, or DTT did not alter AOX activity. The reduction level of the quinone pool was higher in mitochondria from cold-stressed than from control cells; furthermore, the content of reduced glutathione was lower in cold-stressed cells. Growth in the presence of an AOX inhibitor was not affected in control cells, whereas in cold-stressed cells, growth was diminished by 50%. Cyanide diminished growth in control cells by 50%, but in cold-stressed cells this inhibitor was ineffective. The data suggest that AOX activity is part of the cellular response to oxidative stress in Euglena .
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17
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Joët T, Morin C, Fischbarg J, Louw AI, Eckstein-Ludwig U, Woodrow C, Krishna S. Why is the Plasmodium falciparum hexose transporter a promising new drug target? Expert Opin Ther Targets 2005; 7:593-602. [PMID: 14498822 DOI: 10.1517/14728222.7.5.593] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Chemotherapy of malaria parasites is limited by established drug resistance and lack of novel treatment options. Intraerythrocytic stages of Plasmodium falciparum, the causative agent of severe malaria, are wholly dependent upon host glucose for energy. A facilitative hexose transporter (PfHT), encoded by a single-copy gene, mediates glucose uptake and is therefore an attractive potential target. The authors first established heterologous expression in Xenopus laevis to allow functional characterisation of PfHT. They then used this expression system to compare the interaction of substrates with PfHT and mammalian Gluts (hexose transporters) and identified important differences between host and parasite transporters. Certain Omethyl derivatives of glucose proved to be particularly useful discriminators between mammalian transporters and PfHT. The authors exploited this selectivity and synthesised an O-3 hexose derivative that potently inhibits PfHT expressed in oocytes. This O-3 derivative (compound 3361) also kills cultured P. falciparum with comparable potency. Compound 3361 acts with reasonable specificity against PfHT orthologues encoded by other parasites such as Plasmodium vivax, Plasmodium yoelii and Plasmodium knowlesi. Multiplication of Plasmodium berghei in a mouse model is also significantly impeded by this compound. These findings validate PfHT as a novel target.
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Affiliation(s)
- T Joët
- Department of Cellular and Molecular Medicine, Infectious Diseases, St George's Hospital Medical School, Cranmer Terrace, London, SW17 ORE, UK
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18
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Abstract
Mitochondria of the malaria parasitePlasmodium falciparumare morphologically different between the asexual and sexual blood stages (gametocytes). In this paper recent findings of mitochondrial heterogeneity are reviewed based on their ultrastructural characteristics, metabolic activities and the differential expression of their genes in these 2 blood stages of the parasite. The existence of NADH dehydrogenase (complex I), succinate dehydrogenase (complex II), cytochrome c reductase (complex III) and cytochrome c oxidase (complex IV) suggests that the biochemically active electron transport system operates in this parasite. There is also an alternative electron transport branch pathway, including an anaerobic function of complex II. One of the functional roles of the mitochondrion in the parasite is the coordination of pyrimidine biosynthesis, the electron transport system and oxygen utilization via dihydroorotate dehydrogenase and coenzyme Q. Complete sets of genes encoding enzymes of the tricarboxylic acid cycle and the ATP synthase complex are predicted fromP. falciparumgenomics information. Other metabolic roles of this organelle include membrane potential maintenance, haem and coenzyme Q biosynthesis, and oxidative phosphorylation. Furthermore, the mitochondrion may be a chemotherapeutic target for antimalarial drug development. The antimalarial drug atovaquone targets the mitochondrion.
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Affiliation(s)
- J Krungkrai
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
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19
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Putignani L, Tait A, Smith HV, Horner D, Tovar J, Tetley L, Wastling JM. Characterization of a mitochondrion-like organelle in Cryptosporidium parvum. Parasitology 2004; 129:1-18. [PMID: 15267107 DOI: 10.1017/s003118200400527x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cryptosporidium parvum is a protozoan parasite that causes widespread diarrhoeal disease in humans and other animals and is responsible for large waterborne outbreaks of cryptosporidiosis. Unlike many organisms belonging to the phylum Apicomplexa, such as Plasmodium spp. and Toxoplasma gondii, there is no clinically proven drug treatment against this parasite. Aspects of the basic biology of C. parvum remain poorly understood, including a detailed knowledge of key metabolic pathways, its genome organization and organellar complement. Previous studies have proposed that C. parvum lacks a relic plastid organelle, or 'apicoplast', but that it may possess a mitochondrion. Here we characterize a mitochondrion-like organelle in C. parvum by (i) ultrastructural and morphological description (ii) localization of heterologous mitochondrial chaperonin antibody probes (iii) phylogenetic analysis of genes encoding mitochondrial transport proteins (iv) identification and analysis of mitochondrion-associated gene sequences. Our descriptive morphological analysis was performed by energy-filtering transmission electron microscopy (EFTEM) of C. hominis and C. parvum. The 'mitochondrion-like' organelle was characterized by labelling the structure with a heterologous mitochondrial chaperonin probe (hsp60) both in immunoelectron microscopy (IMEM) and immunofluorescence (IMF). Phylogenetic analysis of the mitochondrial import system and housekeeping components (hsp60 and hsp70-dnaK) suggested that the C. parvum mitochondrion-like organelle is likely to have descended from a common ancestral apicomplexan mitochondrion. We also identified a partial cDNA sequence coding for an alternative oxidase (AOX) gene, a component of the electron transport chain which can act as an alternative to the terminal mitochondrial respiratory complexes III and IV, which has not yet been reported in any other member of this phylum. Degenerate primers developed to identify selected mitochondrial genes failed to identify either cytochrome oxidase subunit I, or cytochrome b. Taken together, our data aim to provide new insights into the characterization of this Cryptosporidium organelle and a logical framework for future functional investigation.
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Affiliation(s)
- L Putignani
- Division of Infection and Immunity, Institute of Biomedical and Life Science, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
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20
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Roberts CW, Roberts F, Henriquez FL, Akiyoshi D, Samuel BU, Richards TA, Milhous W, Kyle D, McIntosh L, Hill GC, Chaudhuri M, Tzipori S, McLeod R. Evidence for mitochondrial-derived alternative oxidase in the apicomplexan parasite Cryptosporidium parvum: a potential anti-microbial agent target. Int J Parasitol 2004; 34:297-308. [PMID: 15003491 DOI: 10.1016/j.ijpara.2003.11.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Revised: 11/06/2003] [Accepted: 11/06/2003] [Indexed: 10/26/2022]
Abstract
The observation that Plasmodium falciparum possesses cyanide insensitive respiration that can be inhibited by salicylhydroxamic acid (SHAM) and propyl gallate is consistent with the presence of an alternative oxidase (AOX). However, the completion and annotation of the P. falciparum genome project did not identify any protein with convincing similarity to the previously described AOXs from plants, fungi or protozoa. We undertook a survey of the available apicomplexan genome projects in an attempt to address this anomaly. Putative AOX sequences were identified and sequenced from both type 1 and 2 strains of Cryptosporidium parvum. The gene encodes a polypeptide of 336 amino acids and has a predicted N-terminal transit sequence similar to that found in proteins targeted to the mitochondria of other species. The potential of AOX as a target for new anti-microbial agents for C. parvum is evident by the ability of SHAM and 8-hydroxyquinoline to inhibit in vitro growth of C. parvum. In spite of the lack of a good candidate for AOX in either the P. falciparum or Toxoplasma gondii genome projects, SHAM and 8-hydroxyquinoline were found to inhibit the growth of these parasites. Phylogenetic analysis suggests that AOX and the related protein immutans are derived from gene transfers from the mitochondrial endosymbiont and the chloroplast endosymbiont, respectively. These data are consistent with the functional localisation studies conducted thus far, which demonstrate mitochondrial localisation for some AOX and chloroplastidic localization for immutans. The presence of a mitochondrial compartment is further supported by the prediction of a mitochondrial targeting sequence at the N-terminus of the protein and MitoTracker staining of a subcellular compartment in trophozoite and meront stages. These results give insight into the evolution of AOX and demonstrate the potential of targeting the alternative pathway of respiration in apicomplexans.
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Affiliation(s)
- Craig W Roberts
- Department of Immunology, Strathclyde Institute for Biomedical Life Sciences, University of Strathclyde, Glasgow, Scotland, UK
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21
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Suzuki T, Hashimoto T, Yabu Y, Kido Y, Sakamoto K, Nihei CI, Hato M, Suzuki SI, Amano Y, Nagai K, Hosokawa T, Minagawa N, Ohta N, Kita K. Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: phylogenetic and therapeutic implications. Biochem Biophys Res Commun 2004; 313:1044-52. [PMID: 14706648 DOI: 10.1016/j.bbrc.2003.12.038] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cryptosporidium parvum is a parasitic protozoan that causes the diarrheal disease cryptosporidiosis, for which no satisfactory chemotherapy is currently available. Although the presence of mitochondria in this parasite has been suggested, its respiratory system is poorly understood due to difficulties in performing biochemical analyses. In order to better understand the respiratory chain of C. parvum, we surveyed its genomic DNA database in GenBank and identified a partial sequence encoding cyanide-insensitive alternative oxidase (AOX). Based on this sequence, we cloned C. parvum AOX (CpAOX) cDNA from the phylum apicomplexa for the first time. The deduced amino acid sequence (335 a.a.) of CpAOX contains diiron coordination motifs (-E-, -EXXH-) that are conserved among AOXs. Phylogenetic analysis suggested that CpAOX is a mitochondrial-type AOX, possibly derived from mitochondrial endosymbiont gene transfer. The recombinant enzyme expressed in Escherichia coli showed quinol oxidase activity. This activity was insensitive to cyanide and highly sensitive to ascofuranone, a specific inhibitor of trypanosome AOX.
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Affiliation(s)
- Takashi Suzuki
- Department of Molecular Parasitology, Nagoya City University, Graduate School of Medical Sciences, Nagoya 467-8601, Japan
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22
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Biagini GA, O'Neill PM, Nzila A, Ward SA, Bray PG. Antimalarial chemotherapy: young guns or back to the future? Trends Parasitol 2003; 19:479-87. [PMID: 14580958 DOI: 10.1016/j.pt.2003.09.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Giancarlo A Biagini
- Division of Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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23
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Oliveira PL, Oliveira MF. Vampires, Pasteur and reactive oxygen species. Is the switch from aerobic to anaerobic metabolism a preventive antioxidant defence in blood-feeding parasites? FEBS Lett 2002; 525:3-6. [PMID: 12163151 DOI: 10.1016/s0014-5793(02)03026-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Several species of parasites show a reduction of their respiratory activity along their developmental cycles after they start to feed on vertebrate blood, relying on anaerobic degradation of carbohydrates to achieve their energy requirements. Usually, these parasites choose not to breathe despite of living in an environment of high oxygen availability such as vertebrate blood. Absence of the 'Pasteur effect' in most of these parasites has been well documented. Interestingly, together with the switch from aerobic to anaerobic metabolism in these parasites, there is clear evidence pointing to an increase in their antioxidant defences. As the respiratory chain in mitochondria is a major site of production of reactive oxygen species (ROS), we propose here that the arrest of respiration constitutes an adaptation to avoid the toxic effects of ROS. This situation would be especially critical for blood-feeding parasites because ROS produced in mitochondria would interact with pro-oxidant products of blood digestion, such as haem and/or iron, and increase the oxidative damage to the parasite's cells.
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Affiliation(s)
- Pedro L Oliveira
- Departamento de Bioqui;mica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowsky, s/n, Cidade Universitária, Ilha do Fundão, RJ 21941-590, Rio de Janeiro, Brazil.
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24
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Monti D, Basilico N, Parapini S, Pasini E, Olliaro P, Taramelli D. Does chloroquine really act through oxidative stress? FEBS Lett 2002; 522:3-5. [PMID: 12095608 DOI: 10.1016/s0014-5793(02)02881-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To assess whether molecular oxygen and oxidative stress contribute to chloroquine activity, we cultivated strains of Plasmodium falciparum in erythrocytes with carboxyhemoglobin and an atmosphere containing 2% CO, 5% CO(2) and 93% N(2). Results indicate that, contrary to common belief, oxygen is not involved in the activity of chloroquine. Reactive radicals formation is suggested.
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Affiliation(s)
- Diego Monti
- Department of Organic Chemistry, University of Milan, CNR-ISTM, Via Venezian 21, Italy.
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25
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Sakano K. Metabolic regulation of pH in plant cells: role of cytoplasmic pH in defense reaction and secondary metabolism. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 206:1-44. [PMID: 11407758 DOI: 10.1016/s0074-7696(01)06018-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A new biochemical pH-stat hypothesis that revised the classic hypothesis is presented to understand the metabolic regulation of intracellular pH in plant cells. Alternative pathway glycolysis, alternative pathway respiration and malate-derived lactic and alcoholic fermentation (alternative pathway fermentation), all unique to plants, are integrated into a regulatory mechanism of pH in the cytoplasm. Its uniqueness to plant kingdom is discussed from the evolutionary viewpoint: it is suggested that when the ancestors of extant terrestrial plants expanded their habitat from oceans to freshwater, they abandoned a "sodium system" and adopted a "proton system" for nutrient uptake. Validity of the new hypothesis is examined with available data on a secondary active transport, anoxia and other experimental evidence. The hypothesis predicts that biotic and abiotic stress-induced cytoplasmic acidification triggers synthesis of phytoalexins and other secondary metabolites. Possible roles of cyanide-resistant alternative pathway respiration in the secondary metabolite production, metabolic switching between primary and secondary metabolisms, and defense reactions are proposed.
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Affiliation(s)
- K Sakano
- Department of Plant Physiology, National Institute of Agrobiological Resources, Tsukuba, Ibaraki, Japan
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26
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Suswam E, Kyle D, Lang-Unnasch N. Plasmodium falciparum: the effects of atovaquone resistance on respiration. Exp Parasitol 2001; 98:180-7. [PMID: 11560411 DOI: 10.1006/expr.2001.4639] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atovaquone is an antimalarial agent that specifically inhibits the cytochrome bc(1) complex of the cytochrome pathway. High-level atovaquone resistance is associated with a point mutation in the cytochrome b gene. A pair of isogenic clinical isolates of Plasmodium falciparum derived from before and after the acquisition of atovaquone resistance was used to determine whether the change in the cytochrome b gene resulted in changes in respiration in response to atovaquone. Since P. falciparum appears to utilize a branched respiratory system comprising both the cytochrome and an alternative respiratory pathway, the proportion of each pathway utilized by the sensitive and resistant parasites was investigated. Atovaquone inhibited total parasite oxygen consumption by up to 66% in the sensitive isolate but only up to 28% in the resistant isolate. Both the atovaquone-sensitive and the atovaquone-resistant parasites were comparably sensitive to the alternative pathway inhibitor, salicylhydroxamic acid. Atovaquone appeared to partially inhibit the rate of oxygen consumed through the alternative pathway in only the atovaquone-sensitive isolate. Cross resistance was noted between atovaquone and a new antimalarial agent WR243251. However, the level of WR243251 resistance was very modest compared to the level of atovaquone resistance. WR243251 was shown to rapidly reduce the rate of parasite oxygen consumption by almost 80% in the atovaquone-sensitive isolate and by 57% in the atovaquone-resistant isolate. Drug interaction studies suggest that atovaquone and WR243251 may inhibit growth additively or with mild synergy. Together, these results suggest that while WR243251 may inhibit respiration, its target of action probably differs from that of atovaquone.
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Affiliation(s)
- E Suswam
- Division of Geographic Medicine, University of Alabama at Birmingham, 1530 South 3rd Avenue, Birmingham, AL 35294-2170, U.S.A
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27
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Uyemura SA, Luo S, Moreno SN, Docampo R. Oxidative phosphorylation, Ca(2+) transport, and fatty acid-induced uncoupling in malaria parasites mitochondria. J Biol Chem 2000; 275:9709-15. [PMID: 10734123 DOI: 10.1074/jbc.275.13.9709] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Respiration, oxidative phosphorylation, calcium uptake, and the mitochondrial membrane potential of trophozoites of the malaria parasite Plasmodium berghei were assayed in situ after permeabilization with digitonin. ADP promoted an oligomycin-sensitive transition from resting to phosphorylating respiration. Respiration was sensitive to antimycin A and cyanide. The capacity of trophozoites to sustain oxidative phosphorylation was additionally supported by the detection of an oligomycin-sensitive decrease in mitochondrial membrane potential induced by ADP. Phosphorylation of ADP could be obtained in permeabilized trophozoites in the presence of succinate, citrate, alpha-ketoglutarate, glutamate, malate, dihydroorotate, alpha-glycerophosphate, and N,N,N',N'-tetramethyl-p-phenylenediamine. Ca(2+) uptake caused membrane depolarization compatible with the existence of an electrogenically mediated Ca(2+) transport system in these mitochondria. An uncoupling effect of fatty acids was partly reversed by bovine serum albumin, ATP, or GTP and not affected by atractyloside, ADP, glutamate, or malonate. Evidence for the presence of a mitochondrial uncoupling protein in P. berghei was also obtained by using antibodies raised against plant uncoupling mitochondrial protein. Together these results provide the first direct biochemical evidence of mitochondrial function in ATP synthesis and Ca(2+) transport in a malaria parasite and suggest the presence of an H(+) conductance in trophozoites similar to that produced by a mitochondrial uncoupling protein.
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Affiliation(s)
- S A Uyemura
- Laboratory of Molecular Parasitology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA
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28
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Finnegan PM, Wooding AR, Day DA. An alternative oxidase monoclonal antibody recognises a highly conserved sequence among alternative oxidase subunits. FEBS Lett 1999; 447:21-4. [PMID: 10218574 DOI: 10.1016/s0014-5793(99)00259-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The alternative oxidase is found in the inner mitochondrial membranes of plants and some fungi and protists. A monoclonal antibody raised against the alternative oxidase from the aroid lily Sauromatum guttatum has been used extensively to detect the enzyme in these organisms. Using an immunoblotting strategy, the antibody binding site has been localised to the sequence RADEAHHRDVNH within the soybean alternative oxidase 2 protein. Examination of sequence variants showed that A2 and residues C-terminal to H7 are required for recognition by the monoclonal antibody raised against the alternative oxidase. The recognition sequence is highly conserved among all alternative oxidase proteins and is absolutely conserved in 12 of 14 higher plant sequences, suggesting that this antibody will continue to be extremely useful in studying the expression and synthesis of the alternative oxidase.
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Affiliation(s)
- P M Finnegan
- Division of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra, ACT.
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29
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Murphy AD, Lang-Unnasch N. Alternative oxidase inhibitors potentiate the activity of atovaquone against Plasmodium falciparum. Antimicrob Agents Chemother 1999; 43:651-4. [PMID: 10049282 PMCID: PMC89175 DOI: 10.1128/aac.43.3.651] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent evidence suggests that the malaria parasite Plasmodium falciparum utilizes a branched respiratory pathway including both a cytochrome chain and an alternative oxidase. This branched respiratory pathway model has been used as a basis for examining the mechanism of action of two antimalarial agents, atovaquone and proguanil. In polarographic assays, atovaquone immediately reduced the parasite oxygen consumption rate in a concentration-dependent manner. This is consistent with its previously described role as an inhibitor of the cytochrome bc1 complex. Atovaquone maximally inhibited the rate of P. falciparum oxygen consumption by 73% +/- 10%. At all atovaquone concentrations tested, the addition of the alternative oxidase inhibitor, salicylhydroxamic acid, resulted in a further decrease in the rate of parasite oxygen consumption. At the highest concentrations of atovaquone tested, the activities of salicylhydroxamic acid and atovaquone appear to overlap, suggesting that at these concentrations, atovaquone partially inhibits the alternative oxidase as well as the cytochrome chain. Drug interaction studies with atovaquone and salicylhydroxamic acid indicate atovaquone's activity against P. falciparum in vitro is potentiated by this alternative oxidase inhibitor, with a sum fractional inhibitory concentration of 0.6. Propyl gallate, another alternative oxidase inhibitor, also potentiated atovaquone's activity, with a sum fractional inhibitory concentration of 0.7. Proguanil, which potentiates atovaquone activity in vitro and in vivo, had a small effect on parasite oxygen consumption in polarographic assays when used alone or in the presence of atovaquone or salicylhydroxamic acid. This suggests that proguanil does not potentiate atovaquone by direct inhibition of either branch of the parasite respiratory chain.
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Affiliation(s)
- A D Murphy
- Department of Medicine, University of Alabama at Birmingham 35294-2170, USA
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30
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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.
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Affiliation(s)
- P L Olliaro
- UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, Geneva, Switzerland
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31
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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.
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Affiliation(s)
- N Lang-Unnasch
- Department of Medicine, University of Alabama at Birmingham 35294-2170, USA.
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32
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Vercesi AE, Rodrigues CO, Uyemura SA, Zhong L, Moreno SN. Respiration and oxidative phosphorylation in the apicomplexan parasite Toxoplasma gondii. J Biol Chem 1998; 273:31040-7. [PMID: 9813002 DOI: 10.1074/jbc.273.47.31040] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Respiration, oxidative phosphorylation, and the mitochondrial membrane potential (DeltaPsi) of tachyzoites of the apicomplexan parasite Toxoplasma gondii were assayed in situ using very low concentrations of digitonin to render their plasma membrane permeable to succinate, ADP, safranin O, and other small molecules. The rate of basal respiration was slightly increased by digitonin when the cells were incubated in medium containing succinate. ADP promoted an oligomycin-sensitive transition from resting to phosphorylating respiration. Respiration was sensitive to antimycin A and cyanide, and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was oxidized by antimycin A-poisoned mitochondria. The addition of ADP after TMPD/ascorbate also resulted in phosphorylating respiration. The antitoxoplasmosis drug atovaquone, at a very low concentration (0.03 microM), totally inhibited respiration and disrupted the mitochondrial membrane potential. Atovaquone was shown to inhibit the respiratory chain of T. gondii and mammalian mitochondria between cytochrome b and c1 as occurs with antimycin A1. Phosphorylation of ADP could not be obtained in permeabilized tachyzoites in the presence of either pyruvate, 3-oxo-glutarate, glutamate, isocitrate, dihydroorotate, alpha-glycerophosphate, or endogenous substrates. Although ADP phosphorylation was detected in the presence of malate, this activity was rotenone-insensitive and was probably due to the conversion of malate into succinate through a fumarate reductase activity that was detected in mitochondrial extracts. Together these results provide the first direct biochemical evidence that the respiratory chain and oxidative phosphorylation are functional in apicomplexan parasites, although the terminal respiratory pathway is different from that in the mammalian host.
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Affiliation(s)
- A E Vercesi
- Laboratory of Molecular Parasitology, Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA
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Affiliation(s)
- David Lloyd
- Microbiology Group, School of Biosciences, Cardiff University of Wales, PO Box 915, Cardiff CF1 3TL, UK
| | - Giancarlo A Biagini
- Microbiology Group, School of Biosciences, Cardiff University of Wales, PO Box 915, Cardiff CF1 3TL, UK
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