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Morano AA, Ali I, Dvorin JD. Elucidating the spatio-temporal dynamics of the Plasmodium falciparum basal complex. PLoS Pathog 2024; 20:e1012265. [PMID: 38829893 PMCID: PMC11175456 DOI: 10.1371/journal.ppat.1012265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 06/13/2024] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
Asexual replication of Plasmodium falciparum occurs via schizogony, wherein 16-36 daughter cells are produced within the parasite during one semi-synchronized cytokinetic event. Schizogony requires a divergent contractile ring structure known as the basal complex. Our lab has previously identified PfMyoJ (PF3D7_1229800) and PfSLACR (PF3D7_0214700) as basal complex proteins recruited midway through segmentation. Using ultrastructure expansion microscopy, we localized both proteins to a novel basal complex subcompartment. While both colocalize with the basal complex protein PfCINCH upon recruitment, they form a separate, more basal subcompartment termed the posterior cup during contraction. We also show that PfSLACR is recruited to the basal complex prior to PfMyoJ, and that both proteins are removed unevenly as segmentation concludes. Using live-cell microscopy, we show that actin dynamics are dispensable for basal complex formation, expansion, and contraction. We then show that EF-hand containing P. falciparum Centrin 2 partially localizes to this posterior cup of the basal complex and that it is essential for growth and replication, with variable defects in basal complex contraction and synchrony. Finally, we demonstrate that free intracellular calcium is necessary but not sufficient for basal complex contraction in P. falciparum. Thus, we demonstrate dynamic spatial compartmentalization of the Plasmodium falciparum basal complex, identify an additional basal complex protein, and begin to elucidate the unique mechanism of contraction utilized by P. falciparum, opening the door for further exploration of Apicomplexan cellular division.
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Affiliation(s)
- Alexander A. Morano
- Biological and Biomedical Sciences, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Ilzat Ali
- Biological and Biomedical Sciences, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Jeffrey D. Dvorin
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
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2
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Basco LK. Cultivation of Asexual Intraerythrocytic Stages of Plasmodium falciparum. Pathogens 2023; 12:900. [PMID: 37513747 PMCID: PMC10384318 DOI: 10.3390/pathogens12070900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Successfully developed in 1976, the continuous in vitro culture of Plasmodium falciparum has many applications in the field of malaria research. It has become an important experimental model that directly uses a human pathogen responsible for a high prevalence of morbidity and mortality in many parts of the world and is a major source of biological material for immunological, biochemical, molecular, and pharmacological studies. Until present, the basic techniques described by Trager and Jensen and Haynes et al. remain unchanged in many malaria research laboratories. Nonetheless, different factors, including culture media, buffers, serum substitutes and supplements, sources of erythrocytes, and conditions of incubation (especially oxygen concentration), have been modified by different investigators to adapt the original technique in their laboratories or enhance the in vitro growth of the parasites. The possible effects and benefits of these modifications for the continuous cultivation of asexual intraerythrocytic stages of P. falciparum, as well as future challenges in developing a serum-free cultivation system and axenic cultures, are discussed.
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Affiliation(s)
- Leonardo K Basco
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique-Hôpitaux de Marseille (AP-HM), Service de Santé des Armées (SSA), Unité Mixte de Recherche (UMR) Vecteurs-Infections Tropicales et Méditerranéennes (VITROME), 13005 Marseille, France
- Institut Hospitalo-Universitaire-Méditerranée Infection, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
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3
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Down the membrane hole: Ion channels in protozoan parasites. PLoS Pathog 2022; 18:e1011004. [PMID: 36580479 PMCID: PMC9799330 DOI: 10.1371/journal.ppat.1011004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Parasitic diseases caused by protozoans are highly prevalent around the world, disproportionally affecting developing countries, where coinfection with other microorganisms is common. Control and treatment of parasitic infections are constrained by the lack of specific and effective drugs, plus the rapid emergence of resistance. Ion channels are main drug targets for numerous diseases, but their potential against protozoan parasites is still untapped. Ion channels are membrane proteins expressed in all types of cells, allowing for the flow of ions between compartments, and regulating cellular functions such as membrane potential, excitability, volume, signaling, and death. Channels and transporters reside at the interface between parasites and their hosts, controlling nutrient uptake, viability, replication, and infectivity. To understand how ion channels control protozoan parasites fate and to evaluate their suitability for therapeutics, we must deepen our knowledge of their structure, function, and modulation. However, methodological approaches commonly used in mammalian cells have proven difficult to apply in protozoans. This review focuses on ion channels described in protozoan parasites of clinical relevance, mainly apicomplexans and trypanosomatids, highlighting proteins for which molecular and functional evidence has been correlated with their physiological functions.
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4
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Abstract
Human malaria, caused by infection with Plasmodium parasites, remains one of the most important global public health problems, with the World Health Organization reporting more than 240 million cases and 600,000 deaths annually as of 2020 (World malaria report 2021). Our understanding of the biology of these parasites is critical for development of effective therapeutics and prophylactics, including both antimalarials and vaccines. Plasmodium is a protozoan organism that is intracellular for most of its life cycle. However, to complete its complex life cycle and to allow for both amplification and transmission, the parasite must egress out of the host cell in a highly regulated manner. This review discusses the major pathways and proteins involved in the egress events during the Plasmodium life cycle-merozoite and gametocyte egress out of red blood cells, sporozoite egress out of the oocyst, and merozoite egress out of the hepatocyte. The similarities, as well as the differences, between the various egress pathways of the parasite highlight both novel cell biology and potential therapeutic targets to arrest its life cycle.
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Affiliation(s)
- Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel E Goldberg
- Division of Infectious Diseases, Department of Medicine; and Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA;
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5
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Hoff CC, Azevedo MF, Thurler AB, Maluf SEC, Melo PMS, del Rivero MA, González-Bacerio J, Carmona AK, Budu A, Gazarini ML. Overexpression of Plasmodium falciparum M1 Aminopeptidase Promotes an Increase in Intracellular Proteolysis and Modifies the Asexual Erythrocytic Cycle Development. Pathogens 2021; 10:pathogens10111452. [PMID: 34832608 PMCID: PMC8618464 DOI: 10.3390/pathogens10111452] [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: 09/11/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 11/16/2022] Open
Abstract
Plasmodium falciparum, the most virulent of the human malaria parasite, is responsible for high mortality rates worldwide. We studied the M1 alanyl-aminopeptidase of this protozoan (PfA-M1), which is involved in the final stages of hemoglobin cleavage, an essential process for parasite survival. Aiming to help in the rational development of drugs against this target, we developed a new strain of P. falciparum overexpressing PfA-M1 without the signal peptide (overPfA-M1). The overPfA-M1 parasites showed a 2.5-fold increase in proteolytic activity toward the fluorogenic substrate alanyl-7-amido-4-methylcoumarin, in relation to the wild-type group. Inhibition studies showed that overPfA-M1 presented a lower sensitivity against the metalloaminopeptidase inhibitor bestatin and to other recombinant PfA-M1 inhibitors, in comparison with the wild-type strain, indicating that PfA-M1 is a target for the in vitro antimalarial activity of these compounds. Moreover, overPfA-M1 parasites present a decreased in vitro growth, showing a reduced number of merozoites per schizont, and also a decrease in the iRBC area occupied by the parasite in trophozoite and schizont forms when compared to the controls. Interestingly, the transgenic parasite displays an increase in the aminopeptidase activity toward Met-, Ala-, Leu- and Arg-7-amido-4-methylcoumarin. We also investigated the potential role of calmodulin and cysteine proteases in PfA-M1 activity. Taken together, our data show that the overexpression of PfA-M1 in the parasite cytosol can be a suitable tool for the screening of antimalarials in specific high-throughput assays and may be used for the identification of intracellular molecular partners that modulate their activity in P. falciparum.
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Affiliation(s)
- Carolina C. Hoff
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
| | - Mauro F. Azevedo
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
| | - Adriana B. Thurler
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Sarah El Chamy Maluf
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Pollyana M. S. Melo
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Maday Alonso del Rivero
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, La Habana 10400, Cuba; (M.A.d.R.); (J.G.-B.)
| | - Jorge González-Bacerio
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, La Habana 10400, Cuba; (M.A.d.R.); (J.G.-B.)
| | - Adriana K. Carmona
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Alexandre Budu
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
- Correspondence: (A.B.); (M.L.G.)
| | - Marcos L. Gazarini
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
- Correspondence: (A.B.); (M.L.G.)
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6
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Sharma M, Choudhury H, Roy R, Michaels SA, Ojo KK, Bansal A. CDPKs: The critical decoders of calcium signal at various stages of malaria parasite development. Comput Struct Biotechnol J 2021; 19:5092-5107. [PMID: 34589185 PMCID: PMC8453137 DOI: 10.1016/j.csbj.2021.08.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Calcium ions are used as important signals during various physiological processes. In malaria parasites, Plasmodium spp., calcium dependent protein kinases (CDPKs) have acquired the unique ability to sense and transduce calcium signals at various critical steps during the lifecycle, either through phosphorylation of downstream substrates or mediating formation of high molecular weight protein complexes. Calcium signaling cascades establish important crosstalk events with signaling pathways mediated by other secondary messengers such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). CDPKs play critical roles at various important physiological steps during parasite development in vertebrates and mosquitoes. They are also important for transmission of the parasite between the two hosts. Combined with the fact that CDPKs are not present in humans, they continue to be pursued as important targets for development of anti-malarial drugs.
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Affiliation(s)
- Manish Sharma
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Himashree Choudhury
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajarshi Roy
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Samantha A. Michaels
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Abhisheka Bansal
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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7
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de Oliveira LS, Alborghetti MR, Carneiro RG, Bastos IMD, Amino R, Grellier P, Charneau S. Calcium in the Backstage of Malaria Parasite Biology. Front Cell Infect Microbiol 2021; 11:708834. [PMID: 34395314 PMCID: PMC8355824 DOI: 10.3389/fcimb.2021.708834] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/14/2021] [Indexed: 12/26/2022] Open
Abstract
The calcium ion (Ca2+) is a ubiquitous second messenger involved in key biological processes in prokaryotes and eukaryotes. In Plasmodium species, Ca2+ signaling plays a central role in the parasite life cycle. It has been associated with parasite development, fertilization, locomotion, and host cell infection. Despite the lack of a canonical inositol-1,4,5-triphosphate receptor gene in the Plasmodium genome, pharmacological evidence indicates that inositol-1,4,5-triphosphate triggers Ca2+ mobilization from the endoplasmic reticulum. Other structures such as acidocalcisomes, food vacuole and mitochondria are proposed to act as supplementary intracellular Ca2+ reservoirs. Several Ca2+-binding proteins (CaBPs) trigger downstream signaling. Other proteins with no EF-hand motifs, but apparently involved with CaBPs, are depicted as playing an important role in the erythrocyte invasion and egress. It is also proposed that a cross-talk among kinases, which are not members of the family of Ca2+-dependent protein kinases, such as protein kinases G, A and B, play additional roles mediated indirectly by Ca2+ regulation. This statement may be extended for proteins directly related to invasion or egress, such as SUB1, ERC, IMC1I, IMC1g, GAP45 and EBA175. In this review, we update our understanding of aspects of Ca2+-mediated signaling correlated to the developmental stages of the malaria parasite life cycle.
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Affiliation(s)
- Lucas Silva de Oliveira
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
- UMR 7245 MCAM, Molécules de Communication et Adaptation des Micro-organismes, Muséum National d’Histoire Naturelle, CNRS, Équipe Parasites et Protistes Libres, Paris, France
| | - Marcos Rodrigo Alborghetti
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
| | - Renata Garcia Carneiro
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Izabela Marques Dourado Bastos
- Laboratory of Host-Pathogen Interaction, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Rogerio Amino
- Unité Infection et Immunité Paludéennes, Institut Pasteur, Paris, France
| | - Philippe Grellier
- UMR 7245 MCAM, Molécules de Communication et Adaptation des Micro-organismes, Muséum National d’Histoire Naturelle, CNRS, Équipe Parasites et Protistes Libres, Paris, France
| | - Sébastien Charneau
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
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8
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Fraser M, Matuschewski K, Maier AG. Of membranes and malaria: phospholipid asymmetry in Plasmodium falciparum-infected red blood cells. Cell Mol Life Sci 2021; 78:4545-4561. [PMID: 33713154 PMCID: PMC11071739 DOI: 10.1007/s00018-021-03799-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/04/2021] [Accepted: 02/23/2021] [Indexed: 11/29/2022]
Abstract
Malaria is a vector-borne parasitic disease with a vast impact on human history, and according to the World Health Organisation, Plasmodium parasites still infect over 200 million people per year. Plasmodium falciparum, the deadliest parasite species, has a remarkable ability to undermine the host immune system and cause life-threatening disease during blood infection. The parasite's host cells, red blood cells (RBCs), generally maintain an asymmetric distribution of phospholipids in the two leaflets of the plasma membrane bilayer. Alterations to this asymmetry, particularly the exposure of phosphatidylserine (PS) in the outer leaflet, can be recognised by phagocytes. Because of the importance of innate immune defence numerous studies have investigated PS exposure in RBCs infected with P. falciparum, but have reached different conclusions. Here we review recent advancements in our understanding of the molecular mechanisms which regulate asymmetry in RBCs, and whether infection with the P. falciparum parasite results in changes to PS exposure. On the balance of evidence, it is likely that membrane asymmetry is disrupted in parasitised RBCs, though some methodological issues need addressing. We discuss the potential causes and consequences of altered asymmetry in parasitised RBCs, particularly for in vivo interactions with the immune system, and the role of host-parasite co-evolution. We also examine the potential asymmetric state of parasite membranes and summarise current knowledge on the parasite proteins, which could regulate asymmetry in these membranes. Finally, we highlight unresolved questions at this time and the need for interdisciplinary approaches to uncover the machinery which enables P. falciparum parasites to hide in mature erythrocytes.
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Affiliation(s)
- Merryn Fraser
- Research School of Biology, The Australian National University, Canberra, Australia
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Alexander G Maier
- Research School of Biology, The Australian National University, Canberra, Australia.
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9
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Fraser M, Jing W, Bröer S, Kurth F, Sander LE, Matuschewski K, Maier AG. Breakdown in membrane asymmetry regulation leads to monocyte recognition of P. falciparum-infected red blood cells. PLoS Pathog 2021; 17:e1009259. [PMID: 33600495 PMCID: PMC7891792 DOI: 10.1371/journal.ppat.1009259] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023] Open
Abstract
The human malaria parasite Plasmodium falciparum relies on lipids to survive; this makes its lipid metabolism an attractive drug target. The lipid phosphatidylserine (PS) is usually confined to the inner leaflet of the red blood cell membrane (RBC) bilayer; however, some studies suggest that infection with the intracellular parasite results in the presence of this lipid in the RBC membrane outer leaflet, where it could act as a recognition signal to phagocytes. Here, we used fluorescent lipid analogues and probes to investigate the enzymatic reactions responsible for maintaining asymmetry between membrane leaflets, and found that in parasitised RBCs the maintenance of membrane asymmetry was partly disrupted, and PS was increased in the outer leaflet. We examined the underlying causes for the differences between uninfected and infected RBCs using fluorescent dyes and probes, and found that calcium levels increased in the infected RBC cytoplasm, whereas membrane cholesterol was depleted from the erythrocyte plasma membrane. We explored the resulting effect of PS exposure on enhanced phagocytosis by monocytes, and show that infected RBCs must expend energy to limit phagocyte recognition, and provide experimental evidence that PS exposure contributes to phagocytic recognition of P. falciparum-infected RBCs. Together, these findings underscore the pivotal role for PS exposure on the surface of Plasmodium falciparum-infected erythrocytes for in vivo interactions with the host immune system, and provide a rationale for targeted antimalarial drug design.
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Affiliation(s)
- Merryn Fraser
- Research School of Biology, The Australian National University, Canberra, Australia
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Weidong Jing
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Stefan Bröer
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Florian Kurth
- Department of Infectious Diseases and Pulmonary Medicine, Charité-Universitätsmedizin Berlin, Germany
- Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Department of Medicine, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Leif-Erik Sander
- Department of Infectious Diseases and Pulmonary Medicine, Charité-Universitätsmedizin Berlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Alexander G. Maier
- Research School of Biology, The Australian National University, Canberra, Australia
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10
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Borges-Pereira L, Thomas SJ, Dos Anjos E Silva AL, Bartlett PJ, Thomas AP, Garcia CRS. The genetic Ca 2+ sensor GCaMP3 reveals multiple Ca 2+ stores differentially coupled to Ca 2+ entry in the human malaria parasite Plasmodium falciparum. J Biol Chem 2020; 295:14998-15012. [PMID: 32848018 DOI: 10.1074/jbc.ra120.014906] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/12/2020] [Indexed: 12/31/2022] Open
Abstract
Cytosolic Ca2+ regulates multiple steps in the host-cell invasion, growth, proliferation, and egress of blood-stage Plasmodium falciparum, yet our understanding of Ca2+ signaling in this endemic malaria parasite is incomplete. By using a newly generated transgenic line of P. falciparum (PfGCaMP3) that expresses constitutively the genetically encoded Ca2+ indicator GCaMP3, we have investigated the dynamics of Ca2+ release and influx elicited by inhibitors of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase pumps, cyclopiazonic acid (CPA), and thapsigargin (Thg). Here we show that in isolated trophozoite phase parasites: (i) both CPA and Thg release Ca2+ from intracellular stores in P. falciparum parasites; (ii) Thg is able to induce Ca2+ release from an intracellular compartment insensitive to CPA; (iii) only Thg is able to activate Ca2+ influx from extracellular media, through a mechanism resembling store-operated Ca2+ entry, typical of mammalian cells; and (iv) the Thg-sensitive Ca2+ pool is unaffected by collapsing the mitochondria membrane potential with the uncoupler carbonyl cyanide m-chlorophenyl hydrazone or the release of acidic Ca2+ stores with nigericin. These data suggest the presence of two Ca2+ pools in P. falciparum with differential sensitivity to the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase pump inhibitors, and only the release of the Thg-sensitive Ca2+ store induces Ca2+ influx. Activation of the store-operated Ca2+ entry-like Ca2+ influx may be relevant for controlling processes such as parasite invasion, egress, and development mediated by kinases, phosphatases, and proteases that rely on Ca2+ levels for their activation.
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Affiliation(s)
- Lucas Borges-Pereira
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brasil; Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | - Samantha J Thomas
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | | | - Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA.
| | - Célia R S Garcia
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brasil.
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11
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An Endoplasmic Reticulum CREC Family Protein Regulates the Egress Proteolytic Cascade in Malaria Parasites. mBio 2020; 11:mBio.03078-19. [PMID: 32098818 PMCID: PMC7042697 DOI: 10.1128/mbio.03078-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The endoplasmic reticulum (ER) is thought to play an essential role during egress of malaria parasites because the ER is assumed to be required for biogenesis and secretion of egress-related organelles. However, no proteins localized to the parasite ER have been shown to play a role in egress of malaria parasites. In this study, we generated conditional mutants of the Plasmodium falciparum endoplasmic reticulum-resident calcium-binding protein (PfERC), a member of the CREC family. Knockdown of the PfERC gene showed that this gene is essential for asexual growth of P. falciparum Analysis of the intraerythrocytic life cycle revealed that PfERC is essential for parasite egress but is not required for protein trafficking or calcium storage. We found that PfERC knockdown prevents the rupture of the parasitophorous vacuole membrane. This is because PfERC knockdown inhibited the proteolytic maturation of the subtilisin-like serine protease SUB1. Using double mutant parasites, we showed that PfERC is required for the proteolytic maturation of the essential aspartic protease plasmepsin X, which is required for SUB1 cleavage. Further, we showed that processing of substrates downstream of the proteolytic cascade is inhibited by PfERC knockdown. Thus, these data establish that the ER-resident CREC family protein PfERC is a key early regulator of the egress proteolytic cascade of malaria parasites.IMPORTANCE The divergent eukaryotic parasites that cause malaria grow and divide within a vacuole inside a host cell, which they have to break open once they finish cell division. The egress of daughter parasites requires the activation of a proteolytic cascade, and a subtilisin-like protease initiates a proteolytic cascade to break down the membranes blocking egress. It is assumed that the parasite endoplasmic reticulum plays a role in this process, but the proteins in this organelle required for egress remain unknown. We have identified an early ER-resident regulator essential for the maturation of the recently discovered aspartic protease in the egress proteolytic cascade, plasmepsin X, which is required for maturation of the subtilisin-like protease. Conditional loss of PfERC results in the formation of immature and inactive egress proteases that are unable to breakdown the vacuolar membrane barring release of daughter parasites.
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12
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Peterková L, Kmoníčková E, Ruml T, Rimpelová S. Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective. J Med Chem 2020; 63:1937-1963. [PMID: 32030976 DOI: 10.1021/acs.jmedchem.9b01509] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca2+ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.
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Affiliation(s)
- Lucie Peterková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Eva Kmoníčková
- Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Silvie Rimpelová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.,Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
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13
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Adeoye AO, Olanlokun JO, Tijani H, Lawal SO, Babarinde CO, Akinwole MT, Bewaji CO. Molecular docking analysis of apigenin and quercetin from ethylacetate fraction of Adansonia digitata with malaria-associated calcium transport protein: An in silico approach. Heliyon 2019; 5:e02248. [PMID: 31687530 PMCID: PMC6819832 DOI: 10.1016/j.heliyon.2019.e02248] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/20/2019] [Accepted: 08/05/2019] [Indexed: 11/29/2022] Open
Abstract
Background The investigation and knowledge of calcium handling mechanisms in the plasmodium has been considered as a potential biological target against malaria. Objective This study deals with the evaluation of inhibitory activity of secondary metabolites of ethylacetate partitioned-fraction of Adansonia digitata stem bark extract on malaria-associated protein using in silico docking studies. Materials and methods Molecular docking and virtual screening was performed to understand the mechanism of ligand binding and to identify potent calcium transporter inhibitors. The stem bark extracts of A. digitata contains rich sources of phytochemicals. The secondary metabolites were determined by HPLC-DAD and HRGC-MS analysis. The major chemical constituent present in the ethylacetate partitioned-fraction of A. digitata stem bark extract were examined for their antiplasmodial activity and were also involved in docking study. Results The secondary metabolites, quercetin and apigenin inhibited the formation of β-hematin. The results showed that all the selected compounds in the A. digitata showed binding energy ranging between -6.5 kcal/mol and -7.1 kcal/mol. Among the two chemical constituents, apigenin has the highest docking score along with the highest number of hydrogen bonds formed when compared to quercetin. Analysis of the results suggests that apigenin and quercetin could act as an anti-malaria agent. Conclusion Molecular docking analysis could lead to further development of potent calcium transporter inhibitors for the prevention and treatment of malaria and related conditions.
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Affiliation(s)
- Akinwunmi O Adeoye
- Department of Biochemistry, Federal University Oye Ekiti, Ekiti State, Nigeria.,Department of Biochemistry, University of Ilorin, Kwara State, Nigeria
| | - John O Olanlokun
- Biomembrane and Biotechnology Laboratory, Department of Biochemistry, University of Ibadan, Oyo State, Nigeria
| | - Habib Tijani
- Department of Biochemistry, University of Ilorin, Kwara State, Nigeria
| | - Segun O Lawal
- Biomembrane and Biotechnology Laboratory, Department of Biochemistry, University of Ibadan, Oyo State, Nigeria
| | - Cecilia O Babarinde
- Biomembrane and Biotechnology Laboratory, Department of Biochemistry, University of Ibadan, Oyo State, Nigeria
| | - Mobolaji T Akinwole
- Biomembrane and Biotechnology Laboratory, Department of Biochemistry, University of Ibadan, Oyo State, Nigeria
| | - Clement O Bewaji
- Department of Biochemistry, University of Ilorin, Kwara State, Nigeria
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14
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Lehane AM, Dennis ASM, Bray KO, Li D, Rajendran E, McCoy JM, McArthur HM, Winterberg M, Rahimi F, Tonkin CJ, Kirk K, van Dooren GG. Characterization of the ATP4 ion pump in Toxoplasma gondii. J Biol Chem 2019; 294:5720-5734. [PMID: 30723156 DOI: 10.1074/jbc.ra118.006706] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/31/2019] [Indexed: 12/22/2022] Open
Abstract
The Plasmodium falciparum ATPase PfATP4 is the target of a diverse range of antimalarial compounds, including the clinical drug candidate cipargamin. PfATP4 was originally annotated as a Ca2+ transporter, but recent evidence suggests that it is a Na+ efflux pump, extruding Na+ in exchange for H+ Here we demonstrate that ATP4 proteins belong to a clade of P-type ATPases that are restricted to apicomplexans and their closest relatives. We employed a variety of genetic and physiological approaches to investigate the ATP4 protein of the apicomplexan Toxoplasma gondii, TgATP4. We show that TgATP4 is a plasma membrane protein. Knockdown of TgATP4 had no effect on resting pH or Ca2+ but rendered parasites unable to regulate their cytosolic Na+ concentration ([Na+]cyt). PfATP4 inhibitors caused an increase in [Na+]cyt and a cytosolic alkalinization in WT but not TgATP4 knockdown parasites. Parasites in which TgATP4 was knocked down or disrupted exhibited a growth defect, attributable to reduced viability of extracellular parasites. Parasites in which TgATP4 had been disrupted showed reduced virulence in mice. These results provide evidence for ATP4 proteins playing a key conserved role in Na+ regulation in apicomplexan parasites.
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Affiliation(s)
- Adele M Lehane
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
| | - Adelaide S M Dennis
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Katherine O Bray
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Dongdi Li
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Esther Rajendran
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - James M McCoy
- the Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3052, Australia, and.,the Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Hillary M McArthur
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Markus Winterberg
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Farid Rahimi
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Christopher J Tonkin
- the Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3052, Australia, and.,the Department of Medical Biology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kiaran Kirk
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
| | - Giel G van Dooren
- From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
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15
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Dennis ASM, Rosling JEO, Lehane AM, Kirk K. Diverse antimalarials from whole-cell phenotypic screens disrupt malaria parasite ion and volume homeostasis. Sci Rep 2018; 8:8795. [PMID: 29892073 PMCID: PMC5995868 DOI: 10.1038/s41598-018-26819-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/14/2018] [Indexed: 11/17/2022] Open
Abstract
Four hundred structurally diverse drug-like compounds comprising the Medicines for Malaria Venture's 'Pathogen Box' were screened for their effect on a range of physiological parameters in asexual blood-stage malaria (Plasmodium falciparum) parasites. Eleven of these compounds were found to perturb parasite Na+, pH and volume in a manner consistent with inhibition of the putative Na+ efflux P-type ATPase PfATP4. All eleven compounds fell within the subset of 125 compounds included in the Pathogen Box on the basis of their having been identified as potent inhibitors of the growth of asexual blood-stage P. falciparum parasites. All eleven compounds inhibited the Na+-dependent ATPase activity of parasite membranes and showed reduced efficacy against parasites carrying mutations in PfATP4. This study increases the number of chemically diverse structures known to show a 'PfATP4-associated' phenotype, and adds to emerging evidence that a high proportion (7-9%) of the structurally diverse antimalarial compounds identified in whole cell phenotypic screens share the same mechanism of action, exerting their antimalarial effect via an interaction with PfATP4.
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Affiliation(s)
- Adelaide S M Dennis
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - James E O Rosling
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Adele M Lehane
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
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16
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Cell Swelling Induced by the Antimalarial KAE609 (Cipargamin) and Other PfATP4-Associated Antimalarials. Antimicrob Agents Chemother 2018; 62:AAC.00087-18. [PMID: 29555632 DOI: 10.1128/aac.00087-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/18/2018] [Indexed: 12/15/2022] Open
Abstract
For an increasing number of antimalarial agents identified in high-throughput phenotypic screens, there is evidence that they target PfATP4, a putative Na+ efflux transporter on the plasma membrane of the human malaria parasite Plasmodium falciparum For several such "PfATP4-associated" compounds, it has been noted that their addition to parasitized erythrocytes results in cell swelling. Here we show that six structurally diverse PfATP4-associated compounds, including the clinical candidate KAE609 (cipargamin), induce swelling of both isolated blood-stage parasites and intact parasitized erythrocytes. The swelling of isolated parasites is dependent on the presence of Na+ in the external environment and may be attributed to the osmotic consequences of Na+ uptake. The swelling of the parasitized erythrocyte results in an increase in its osmotic fragility. Countering cell swelling by increasing the osmolarity of the extracellular medium reduces the antiplasmodial efficacy of PfATP4-associated compounds, consistent with cell swelling playing a role in the antimalarial activity of this class of compounds.
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17
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Singh S, Chitnis CE. Molecular Signaling Involved in Entry and Exit of Malaria Parasites from Host Erythrocytes. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026815. [PMID: 28507195 DOI: 10.1101/cshperspect.a026815] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
During the blood stage, Plasmodium spp. merozoites invade host red blood cells (RBCs), multiply, exit, and reinvade uninfected RBCs in a continuing cycle that is responsible for all the clinical symptoms associated with malaria. Entry into (invasion) and exit from (egress) RBCs are highly regulated processes that are mediated by an array of parasite proteins with specific functional roles. Many of these parasite proteins are stored in specialized apical secretory vesicles, and their timely release is critical for successful invasion and egress. For example, the discharge of parasite protein ligands to the apical surface of merozoites is required for interaction with host receptors to mediate invasion, and the timely discharge of proteases and pore-forming proteins helps in permeabilization and dismantling of limiting membranes during egress. This review focuses on our understanding of the signaling mechanisms that regulate apical organelle secretion during host cell invasion and egress by malaria parasites. The review also explores how understanding key signaling mechanisms in the parasite can open opportunities to develop novel strategies to target Plasmodium parasites and eliminate malaria.
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Affiliation(s)
- Shailja Singh
- Department of Parasites and Insect Vectors, Institut Pasteur, 75015 Paris, France.,Shiv Nadar University, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Chetan E Chitnis
- Department of Parasites and Insect Vectors, Institut Pasteur, 75015 Paris, France.,Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi 110067, India
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18
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Abstract
Some hours after invading the erythrocytes of its human host, the malaria parasite Plasmodium falciparum induces an increase in the permeability of the erythrocyte membrane to monovalent ions. The resulting net influx of Na(+) and net efflux of K(+), down their respective concentration gradients, converts the erythrocyte cytosol from an initially high-K(+), low-Na(+) solution to a high-Na(+), low-K(+) solution. The intraerythrocytic parasite itself exerts tight control over its internal Na(+), K(+), Cl(-), and Ca(2+) concentrations and its intracellular pH through the combined actions of a range of membrane transport proteins. The molecular mechanisms underpinning ion regulation in the parasite are receiving increasing attention, not least because PfATP4, a P-type ATPase postulated to be involved in Na(+) regulation, has emerged as a potential antimalarial drug target, susceptible to inhibition by a wide range of chemically unrelated compounds.
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Affiliation(s)
- Kiaran Kirk
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia;
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19
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Pandey K, Ferreira PE, Ishikawa T, Nagai T, Kaneko O, Yahata K. Ca(2+) monitoring in Plasmodium falciparum using the yellow cameleon-Nano biosensor. Sci Rep 2016; 6:23454. [PMID: 27006284 PMCID: PMC4804237 DOI: 10.1038/srep23454] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/07/2016] [Indexed: 11/09/2022] Open
Abstract
Calcium (Ca(2+))-mediated signaling is a conserved mechanism in eukaryotes, including the human malaria parasite, Plasmodium falciparum. Due to its small size (<10 μm) measurement of intracellular Ca(2+) in Plasmodium is technically challenging, and thus Ca(2+) regulation in this human pathogen is not well understood. Here we analyze Ca(2+) homeostasis via a new approach using transgenic P. falciparum expressing the Ca(2+) sensor yellow cameleon (YC)-Nano. We found that cytosolic Ca(2+) concentration is maintained at low levels only during the intraerythrocytic trophozoite stage (30 nM), and is increased in the other blood stages (>300 nM). We determined that the mammalian SERCA inhibitor thapsigargin and antimalarial dihydroartemisinin did not perturb SERCA activity. The change of the cytosolic Ca(2+) level in P. falciparum was additionally detectable by flow cytometry. Thus, we propose that the developed YC-Nano-based system is useful to study Ca(2+) signaling in P. falciparum and is applicable for drug screening.
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Affiliation(s)
- Kishor Pandey
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- Nepal Academy of Science and Technology (NAST), GPO Box: 3323, Khumaltar, Lalitpur, Nepal
| | - Pedro E. Ferreira
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- School of Biological Science, Nanyang Technological University, Singapore
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Takeshi Ishikawa
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Takeharu Nagai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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20
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Budu A, Gomes MM, Melo PM, El Chamy Maluf S, Bagnaresi P, Azevedo MF, Carmona AK, Gazarini ML. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum. Cell Signal 2015; 28:125-135. [PMID: 26689736 DOI: 10.1016/j.cellsig.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022]
Abstract
Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite.
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Affiliation(s)
- Alexandre Budu
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mayrim M Gomes
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil
| | - Pollyana M Melo
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Sarah El Chamy Maluf
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mauro F Azevedo
- Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil
| | - Adriana K Carmona
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
| | - Marcos L Gazarini
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil.
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21
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Di Marino D, D'Annessa I, Coletta A, Via A, Tramontano A. Characterization of the differences in the cyclopiazonic acid binding mode to mammalian and P. Falciparum Ca2+ pumps: a computational study. Proteins 2015; 83:564-74. [PMID: 25581715 PMCID: PMC4342768 DOI: 10.1002/prot.24734] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 10/22/2014] [Accepted: 11/12/2014] [Indexed: 01/04/2023]
Abstract
Despite the investments in malaria research, an effective vaccine has not yet been developed and the causative parasites are becoming increasingly resistant to most of the available drugs. PfATP6, the sarco/endoplasmic reticulum Ca2+ pump (SERCA) of P. falciparum, has been recently genetically validated as a potential antimalarial target and cyclopiazonic acid (CPA) has been found to be a potent inhibitor of SERCAs in several organisms, including P. falciparum. In position 263, PfATP6 displays a leucine residue, whilst the corresponding position in the mammalian SERCA is occupied by a glutamic acid. The PfATP6 L263E mutation has been studied in relation to the artemisinin inhibitory effect on P. falciparum and recent studies have provided evidence that the parasite with this mutation is more susceptible to CPA. Here, we characterized, for the first time, the interaction of CPA with PfATP6 and its mammalian counterpart to understand similarities and differences in the mode of binding of the inhibitor to the two Ca2+ pumps. We found that, even though CPA does not directly interact with the residue in position 263, the presence of a hydrophobic residue in this position in PfATP6 rather than a negatively charged one, as in the mammalian SERCA, entails a conformational arrangement of the binding pocket which, in turn, determines a relaxation of CPA leading to a different binding mode of the compound. Our findings highlight differences between the plasmodial and human SERCA CPA-binding pockets that may be exploited to design CPA derivatives more selective toward PfATP6. Proteins 2015; 83:564–574. © 2015 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Daniele Di Marino
- Department of Physics, Sapienza University, P.Le Aldo Moro 5, Rome, 00185, Italy
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22
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A lactate and formate transporter in the intraerythrocytic malaria parasite, Plasmodium falciparum. Nat Commun 2015; 6:6721. [PMID: 25823844 DOI: 10.1038/ncomms7721] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 02/23/2015] [Indexed: 12/24/2022] Open
Abstract
The intraerythrocytic malaria parasite relies primarily on glycolysis to fuel its rapid growth and reproduction. The major byproduct of this metabolism, lactic acid, is extruded into the external medium. In this study, we show that the human malaria parasite Plasmodium falciparum expresses at its surface a member of the microbial formate-nitrite transporter family (PfFNT), which, when expressed in Xenopus laevis oocytes, transports both formate and lactate. The transport characteristics of PfFNT in oocytes (pH-dependence, inhibitor-sensitivity and kinetics) are similar to those of the transport of lactate and formate across the plasma membrane of mature asexual-stage P. falciparum trophozoites, consistent with PfFNT playing a major role in the efflux of lactate and hence in the energy metabolism of the intraerythrocytic parasite.
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23
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Lourido S, Moreno SNJ. The calcium signaling toolkit of the Apicomplexan parasites Toxoplasma gondii and Plasmodium spp. Cell Calcium 2014; 57:186-93. [PMID: 25605521 DOI: 10.1016/j.ceca.2014.12.010] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 12/21/2022]
Abstract
Apicomplexan parasites have complex life cycles, frequently split between different hosts and reliant on rapid responses as the parasites react to changing environmental conditions. Calcium ion (Ca(2+)) signaling is consequently essential for the cellular and developmental changes that support Apicomplexan parasitism. Apicomplexan genomes reveal a rich repertoire of genes involved in calcium signaling, although many of the genes responsible for observed physiological changes remain unknown. There is evidence, for example, for the presence of a nifedipine-sensitive calcium entry mechanism in Toxoplasma, but the molecular components involved in Ca(2+) entry in both Toxoplasma and Plasmodium, have not been identified. The major calcium stores are the endoplasmic reticulum (ER), the acidocalcisomes, and the plant-like vacuole in Toxoplasma, or the food vacuole in Plasmodium spp. Pharmacological evidence suggests that Ca(2+) release from intracellular stores may be mediated by inositol 1,4,5-trisphosphate (IP3) or cyclic ADP ribose (cADPR) although there is no molecular evidence for the presence of receptors for these second messengers in the parasites. Several Ca(2+)-ATPases are present in Apicomplexans and a putative mitochondrial Ca(2+)/H(+) exchanger has been identified. Apicomplexan genomes contain numerous genes encoding Ca(2+)-binding proteins, with the notable expansion of calcium-dependent protein kinases (CDPKs), whose study has revealed roles in gliding motility, microneme secretion, host cell invasion and egress, and parasite differentiation. Microneme secretion has also been shown to depend on the C2 domain containing protein DOC2 in both Plasmodium spp. and Toxoplasma, providing further evidence for the complex transduction of Ca(2+) signals in these organisms. The characterization of these pathways could lead to the discovery of novel drug targets and to a better understanding of the role of Ca(2+) in these parasites.
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Affiliation(s)
- Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
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24
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Cheemadan S, Ramadoss R, Bozdech Z. Role of calcium signaling in the transcriptional regulation of the apicoplast genome of Plasmodium falciparum. BIOMED RESEARCH INTERNATIONAL 2014; 2014:869401. [PMID: 24877144 PMCID: PMC4022301 DOI: 10.1155/2014/869401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 12/19/2022]
Abstract
Calcium is a universal second messenger that plays an important role in regulatory processes in eukaryotic cells. To understand calcium-dependent signaling in malaria parasites, we analyzed transcriptional responses of Plasmodium falciparum to two calcium ionophores (A23187 and ionomycin) that cause redistribution of intracellular calcium within the cytoplasm. While ionomycin induced a specific transcriptional response defined by up- or downregulation of a narrow set of genes, A23187 caused a developmental arrest in the schizont stage. In addition, we observed a dramatic decrease of mRNA levels of the transcripts encoded by the apicoplast genome during the exposure of P. falciparum to both calcium ionophores. Neither of the ionophores caused any disruptions to the DNA replication or the overall apicoplast morphology. This suggests that the mRNA downregulation reflects direct inhibition of the apicoplast gene transcription. Next, we identify a nuclear encoded protein with a calcium binding domain (EF-hand) that is localized to the apicoplast. Overexpression of this protein (termed PfACBP1) in P. falciparum cells mediates an increased resistance to the ionophores which suggests its role in calcium-dependent signaling within the apicoplast. Our data indicate that the P. falciparum apicoplast requires calcium-dependent signaling that involves a novel protein PfACBP1.
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Affiliation(s)
- Sabna Cheemadan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Ramya Ramadoss
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
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25
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Abstract
As it grows and replicates within the erythrocytes of its host the malaria parasite takes up nutrients from the extracellular medium, exports metabolites and maintains a tight control over its internal ionic composition. These functions are achieved via membrane transport proteins, integral membrane proteins that mediate the passage of solutes across the various membranes that separate the biochemical machinery of the parasite from the extracellular environment. Proteins of this type play a key role in antimalarial drug resistance, as well as being candidate drug targets in their own right. This review provides an overview of recent work on the membrane transport biology of the malaria parasite-infected erythrocyte, encompassing both the parasite-induced changes in the membrane transport properties of the host erythrocyte and the cell physiology of the intracellular parasite itself.
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26
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Koyama FC, Carvalho TLG, Alves E, da Silva HB, de Azevedo MF, Hemerly AS, Garcia CRS. The Structurally Related Auxin and Melatonin Tryptophan-Derivatives and their Roles in Arabidopsis thaliana
and in the Human Malaria Parasite Plasmodium falciparum. J Eukaryot Microbiol 2013; 60:646-51. [DOI: 10.1111/jeu.12080] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 07/25/2013] [Accepted: 07/25/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Fernanda C. Koyama
- Departamento de Parasitologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-000 São Paulo Brazil
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
| | - Thais L. G. Carvalho
- Laboratório de Biologia Molecular de Plantas; Instituto de Bioquímica Médica; Universidade Federal do Rio de Janeiro; 21941-590 Rio de Janeiro Brazil
| | - Eduardo Alves
- Departamento de Parasitologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-000 São Paulo Brazil
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
| | - Henrique B. da Silva
- Departamento de Imunologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-900 São Paulo Brazil
| | - Mauro F. de Azevedo
- Centre for Immunology; Macfarlane Burnet Institute of Medical Research and Public Health; Melbourne Victoria 3004 Australia
| | - Adriana S. Hemerly
- Laboratório de Biologia Molecular de Plantas; Instituto de Bioquímica Médica; Universidade Federal do Rio de Janeiro; 21941-590 Rio de Janeiro Brazil
| | - Célia R. S. Garcia
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
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Spillman NJ, Allen RJW, McNamara CW, Yeung BKS, Winzeler EA, Diagana TT, Kirk K. Na(+) regulation in the malaria parasite Plasmodium falciparum involves the cation ATPase PfATP4 and is a target of the spiroindolone antimalarials. Cell Host Microbe 2013; 13:227-37. [PMID: 23414762 PMCID: PMC3574224 DOI: 10.1016/j.chom.2012.12.006] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/28/2012] [Accepted: 12/20/2012] [Indexed: 01/06/2023]
Abstract
The malaria parasite Plasmodium falciparum establishes in the host erythrocyte plasma membrane new permeability pathways that mediate nutrient uptake into the infected cell. These pathways simultaneously allow Na(+) influx, causing [Na(+)] in the infected erythrocyte cytosol to increase to high levels. The intraerythrocytic parasite itself maintains a low cytosolic [Na(+)] via unknown mechanisms. Here we present evidence that the intraerythrocytic parasite actively extrudes Na(+) against an inward gradient via PfATP4, a parasite plasma membrane protein with sequence similarities to Na(+)-ATPases of lower eukaryotes. Mutations in PfATP4 confer resistance to a potent class of antimalarials, the spiroindolones. Consistent with this, the spiroindolones cause a profound disruption in parasite Na(+) homeostasis, which is attenuated in parasites bearing resistance-conferring mutations in PfATP4. The mutant parasites also show some impairment of Na(+) regulation. Taken together, our results are consistent with PfATP4 being a Na(+) efflux ATPase and a target of the spiroindolones.
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Affiliation(s)
- Natalie J Spillman
- Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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Lima WR, Holder AA, Garcia CRS. Melatonin signaling and its modulation of PfNF-YB transcription factor expression in Plasmodium falciparum. Int J Mol Sci 2013; 14:13704-18. [PMID: 23839089 PMCID: PMC3742212 DOI: 10.3390/ijms140713704] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 06/23/2013] [Accepted: 06/25/2013] [Indexed: 12/15/2022] Open
Abstract
Malaria is one of the most severe tropical infectious diseases. More than 220 million people around the world have a clinical malaria infection and about one million die because of Plasmodium annually. This parasitic pathogen replicates efficiently in its human host making it difficult to eradicate. It is transmitted by mosquito vectors and so far mosquito control programs have not effectively eliminated this transmission. Because of malaria's enormous health and economic impact and the need to develop new control and eventual elimination strategies, a big research effort has been made to better understand the biology of this parasite and its interactions with its vertebrate host. Determination of the genome sequence and organization, the elucidation of the role of key proteins, and cell signaling studies have helped to develop an understanding of the molecular mechanisms that provide the parasite's versatility. The parasite can sense its environment and adapt to benefit its survival, indeed this is essential for it to complete its life cycle. For many years we have studied how the Plasmodium parasite is able to sense melatonin. In this review we discuss the melatonin signaling pathway and its role in the control of Plasmodium replication and development.
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Affiliation(s)
- Wânia Rezende Lima
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508900, Brazil; E-Mail:
| | - Anthony A. Holder
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK; E-Mail:
| | - Célia R. S. Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508900, Brazil; E-Mail:
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Agarwal S, Singh MK, Garg S, Chitnis CE, Singh S. Ca2+-mediated exocytosis of subtilisin-like protease 1: a key step in egress ofPlasmodium falciparummerozoites. Cell Microbiol 2012; 15:910-21. [DOI: 10.1111/cmi.12086] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/30/2012] [Accepted: 11/23/2012] [Indexed: 11/27/2022]
Affiliation(s)
- Shalini Agarwal
- Malaria Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); New Delhi; India
| | - Maneesh Kumar Singh
- Malaria Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); New Delhi; India
| | - Swati Garg
- Malaria Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); New Delhi; India
| | - Chetan E. Chitnis
- Malaria Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); New Delhi; India
| | - Shailja Singh
- Malaria Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); New Delhi; India
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30
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Salcedo-Sora JE, Ward SA, Biagini GA. A yeast expression system for functional and pharmacological studies of the malaria parasite Ca²⁺/H⁺ antiporter. Malar J 2012; 11:254. [PMID: 22853777 PMCID: PMC3488005 DOI: 10.1186/1475-2875-11-254] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Accepted: 07/23/2012] [Indexed: 12/26/2022] Open
Abstract
Background Calcium (Ca2+) signalling is fundamental for host cell invasion, motility, in vivo synchronicity and sexual differentiation of the malaria parasite. Consequently, cytoplasmic free Ca2+ is tightly regulated through the co-ordinated action of primary and secondary Ca2+ transporters. Identifying selective inhibitors of Ca2+ transporters is key towards understanding their physiological role as well as having therapeutic potential, therefore screening systems to facilitate the search for potential inhibitors are a priority. Here, the methodology for the expression of a Calcium membrane transporter that can be scaled to high throughputs in yeast is presented. Methods The Plasmodium falciparum Ca2+/H+ antiporter (PfCHA) was expressed in the yeast Saccharomyces cerevisiae and its activity monitored by the bioluminescence from apoaequorin triggered by divalent cations, such as calcium, magnesium and manganese. Results Bioluminescence assays demonstrated that PfCHA effectively suppressed induced cytoplasmic peaks of Ca2+, Mg2+ and Mn2+ in yeast mutants lacking the homologue yeast antiporter Vcx1p. In the scalable format of 96-well culture plates pharmacological assays with a cation antiporter inhibitor allowed the measurement of inhibition of the Ca2+ transport activity of PfCHA conveniently translated to the familiar concept of fractional inhibitory concentrations. Furthermore, the cytolocalization of this antiporter in the yeast cells showed that whilst PfCHA seems to locate to the mitochondrion of P. falciparum, in yeast PfCHA is sorted to the vacuole. This facilitates the real-time Ca2+-loading assays for further functional and pharmacological studies. Discussion The functional expression of PfCHA in S. cerevisiae and luminescence-based detection of cytoplasmic cations as presented here offer a tractable system that facilitates functional and pharmacological studies in a high-throughput format. PfCHA is shown to behave as a divalent cation/H+ antiporter susceptible to the effects of cation/H+ inhibitors such as KB-R7943. This type of gene expression systems should advance the efforts for the screening of potential inhibitors of this type of divalent cation transporters as part of the malaria drug discovery initiatives and for functional studies in general. Conclusion The expression and activity of the PfCHA detected in yeast by a bioluminescence assay that follows the levels of cytoplasmic Ca2+ as well as Mg2+ and Mn2+ lend itself to high-throughput and quantitative settings for pharmacological screening and functional studies.
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Abstract
Calcium is relevant for several vital functions in apicomplexan parasites, including host cell invasion, parasite motility and differentiation. The ER (endoplasmic reticulum) and calcium-rich acidocalcisomes have been identified as major calcium stores. Other potential calcium-storage organelles include the Golgi, the mitochondrion, the apicoplast and the recently described plant-like vacuole in Toxoplasma gondii. Compared with most eukaryotic systems, apicomplexan parasites contain a reduced number of calcium-related genes, a vast majority of which remain uncharacterized. Several Ca²⁺-ATPases have been described in apicomplexans, several of which are annotated in the different genomes. There is experimental evidence for an IP3 (inositol 1,4,5-trisphosphate)-dependent calcium response in Plasmodium spp. and T. gondii, although no IP3 or ryanodine receptors have been identified. Genes encoding potential calcium channels are present in T. gondi, but not in Plasmodium spp. and Cryptosporidium spp. Effector calcium-binding proteins including calmodulins and CDPK (calcium-dependent protein kinase) genes mainly found in plants have also been described. The characterized CDPKs were found to play important roles in protein secretion, host cell invasion and parasite differentiation. Taken together, the available information on calcium storage and function in apicomplexans, although fragmented, suggest the existence of unique calcium-mediated pathways in these parasites. An in-depth functional characterization of the apicomplexan calcium-related genes could lead to the identification of novel therapeutic targets, and will improve our understanding of the role of calcium in parasite development and virulence.
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Generation of second messengers in Plasmodium. Microbes Infect 2012; 14:787-95. [PMID: 22584103 DOI: 10.1016/j.micinf.2012.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 02/05/2023]
Abstract
Signalling in malaria parasites is a field of growing interest as its components may prove to be valuable drug targets, especially when one considers the burden of a disease that is responsible for up to 500 million infections annually. The scope of this review is to discuss external stimuli in the parasite life cycle and the upstream machinery responsible for translating them into intracellular responses, focussing particularly on the calcium signalling pathway.
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Holder AA, Mohd Ridzuan MA, Green JL. Calcium dependent protein kinase 1 and calcium fluxes in the malaria parasite. Microbes Infect 2012; 14:825-30. [PMID: 22584104 DOI: 10.1016/j.micinf.2012.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/11/2012] [Accepted: 04/11/2012] [Indexed: 01/20/2023]
Abstract
Calcium dependent protein kinases (CDPKs) are found only in plants and alveolates and are distinguished from other kinases by an activation domain that binds calcium directly. Plants contain families of these kinases and their functions are modulated by post translational modifications as well as calcium activation. Apicomplexan parasites also contain CDPK families and this review is focused on CDPK1 in Plasmodium spp. This enzyme has been implicated in parasite motility and host cell invasion and at least two substrates associated with the actomyosin motor complex have been identified. By analogy with the plant CDPKs we propose that its activity is modulated both by post translational modifications and by its subcellular location in a compartment within the parasite's pellicle, which may regulate the calcium concentration required for activation.
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Affiliation(s)
- Anthony A Holder
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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34
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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Bagnaresi P, Nakabashi M, Thomas AP, Reiter RJ, Garcia CRS. The role of melatonin in parasite biology. Mol Biochem Parasitol 2011; 181:1-6. [PMID: 21982826 DOI: 10.1016/j.molbiopara.2011.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 09/21/2011] [Accepted: 09/23/2011] [Indexed: 10/17/2022]
Abstract
Regarded as the circadian hormone in mammals, melatonin is a highly conserved molecule, present in nearly all species. In this review, we discuss the role of this indolamine and its precursors in the cell biology of parasites and the role of the molecule in the physiology of the host. In Plasmodium, melatonin can modulate intracellular concentrations of calcium and cAMP, which in turn can regulate kinase activity and cell cycle. In Trypanosoma infections, modulation of the immune system by melatonin is extremely important in controlling the parasite population. Melatonin also contributes to the inflammatory response to Toxoplasma gondii infection. Thus, there are a number of unique adaptations involving intricate connections between melatonin and the biology of the parasite-host relationship.
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Affiliation(s)
- Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil
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36
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Cruz LND, Alves E, Leal MT, Juliano MA, Rosenthal PJ, Juliano L, Garcia CRS. FRET peptides reveal differential proteolytic activation in intraerythrocytic stages of the malaria parasites Plasmodium berghei and Plasmodium yoelii. Int J Parasitol 2010; 41:363-72. [PMID: 21168413 DOI: 10.1016/j.ijpara.2010.10.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 10/26/2010] [Accepted: 10/27/2010] [Indexed: 11/25/2022]
Abstract
Malaria is still a major health problem in developing countries. It is caused by the protist parasite Plasmodium, in which proteases are activated during the cell cycle. Ca(2+) is a ubiquitous signalling ion that appears to regulate protease activity through changes in its intracellular concentration. Proteases are crucial to Plasmodium development, but the role of Ca(2+) in their activity is not fully understood. Here we investigated the role of Ca(2+) in protease modulation among rodent Plasmodium spp. Using fluorescence resonance energy transfer (FRET) peptides, we verified protease activity elicited by Ca(2+) from the endoplasmatic reticulum (ER) after stimulation with thapsigargin (a sarco/endoplasmatic reticulum Ca(2+)-ATPase (SERCA) inhibitor) and from acidic compartments by stimulation with nigericin (a K(+)/H(+) exchanger) or monensin (a Na(+)/H(+) exchanger). Intracellular (BAPTA/AM) and extracellular (EGTA) Ca(2+) chelators were used to investigate the role played by Ca(2+) in protease activation. In Plasmodium berghei both EGTA and BAPTA blocked protease activation, whilst in Plasmodium yoelii these compounds caused protease activation. The effects of protease inhibitors on thapsigargin-induced proteolysis also differed between the species. Pepstatin A and phenylmethylsulphonyl fluoride (PMSF) increased thapsigargin-induced proteolysis in P. berghei but decreased it in P. yoelii. Conversely, E64 reduced proteolysis in P. berghei but stimulated it in P. yoelii. The data point out key differences in proteolytic responses to Ca(2+) between species of Plasmodium.
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Affiliation(s)
- Laura Nogueira da Cruz
- Department of Parasitology, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374 Edifício Biomédicas II, CEP 05508-900, São Paulo, SP, Brazil
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Krishna S, Pulcini S, Fatih F, Staines H. Artemisinins and the biological basis for the PfATP6/SERCA hypothesis. Trends Parasitol 2010; 26:517-23. [DOI: 10.1016/j.pt.2010.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/28/2022]
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Rotmann A, Sanchez C, Guiguemde A, Rohrbach P, Dave A, Bakouh N, Planelles G, Lanzer M. PfCHA is a mitochondrial divalent cation/H+ antiporter in Plasmodium falciparum. Mol Microbiol 2010; 76:1591-606. [PMID: 20487273 DOI: 10.1111/j.1365-2958.2010.07187.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human malaria parasite Plasmodium falciparum is capable of adapting to vastly different extracellular Ca(2+) environments while maintaining tight control of its intracellular Ca(2+) concentration. The mechanisms underpinning Ca(2+) homeostasis in this important pathogen are only partly understood. Here we have functionally expressed the putative Ca(2+)/H(+) antiporter PfCHA in Xenopus laevis oocytes. Our data suggest that PfCHA mediates H(+)-coupled Ca(2+) and Mn(2+) exchange. The apparent dissociation constant K(M) for Ca(2+) of 2.2 +/- 0.7 mM and the maximal velocity V(max) of 0.6 +/- 0.1 nmol per oocyte per hour are consistent with PfCHA being a low-affinity high-capacity Ca(2+) carrier. In the parasite, PfCHA was found to localize to the mitochondrion. Physiological studies conducted with live parasitized erythrocytes, and using Fluo-4 and Rhod-2 to monitor cytoplasmic and mitochondrial Ca(2+) dynamics, suggest that the mitochondrion serves as a dynamic Ca(2+) store and that PfCHA functions as a Ca(2+) efflux system expelling excess Ca(2+) from the mitochondrion. PfCHA lacks appreciable homologies to the human mitochondrial Ca(2+)/H(+) exchanger and might represent an evolutionary divergent class of mitochondrial cation antiporter, which, in turn, might provide novel opportunities for intervention.
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Affiliation(s)
- Alexander Rotmann
- Hygiene Institut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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39
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Henry RI, Cobbold SA, Allen RJW, Khan A, Hayward R, Lehane AM, Bray PG, Howitt SM, Biagini GA, Saliba KJ, Kirk K. An acid-loading chloride transport pathway in the intraerythrocytic malaria parasite, Plasmodium falciparum. J Biol Chem 2010; 285:18615-26. [PMID: 20332090 DOI: 10.1074/jbc.m110.120980] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The intraerythrocytic malaria parasite exerts tight control over its ionic composition. In this study, a combination of fluorescent ion indicators and (36)Cl(-) flux measurements was used to investigate the transport of Cl(-) and the Cl(-)-dependent transport of "H(+)-equivalents" in mature (trophozoite stage) parasites, isolated from their host erythrocytes. Removal of extracellular Cl(-), resulting in an outward [Cl(-)] gradient, gave rise to a cytosolic alkalinization (i.e. a net efflux of H(+)-equivalents). This was reversed on restoration of extracellular Cl(-). The flux of H(+)-equivalents was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and, when measured in ATP-depleted parasites, showed a pronounced dependence on the pH of the parasite cytosol; the flux was low at cytosolic pH values < 7.2 but increased steeply with cytosolic pH at values > 7.2. (36)Cl(-) influx measurements revealed the presence of a Cl(-) uptake mechanism with characteristics similar to those of the Cl(-)-dependent H(+)-equivalent flux. The intracellular concentration of Cl(-) in the parasite was estimated to be approximately 48 mm in situ. The data are consistent with the intraerythrocytic parasite having in its plasma membrane a 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-sensitive transporter that, under physiological conditions, imports Cl(-) together with H(+)-equivalents, resulting in an intracellular Cl(-) concentration well above that which would occur if Cl(-) ions were distributed passively in accordance with the parasite's large, inwardly negative membrane potential.
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Affiliation(s)
- Roselani I Henry
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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40
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Rohrbach P. Imaging ion flux and ion homeostasis in blood stage malaria parasites. Biotechnol J 2009; 4:812-25. [DOI: 10.1002/biot.200900084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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41
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Teng R, Junankar PR, Bubb WA, Rae C, Mercier P, Kirk K. Metabolite profiling of the intraerythrocytic malaria parasite Plasmodium falciparum by (1)H NMR spectroscopy. NMR IN BIOMEDICINE 2009; 22:292-302. [PMID: 19021153 DOI: 10.1002/nbm.1323] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
NMR spectroscopy was used to identify and quantify compounds in extracts prepared from mature trophozoite-stage Plasmodium falciparum parasites isolated by saponin-permeabilisation of the host erythrocyte. One-dimensional (1)H NMR spectroscopy and four two-dimensional NMR techniques were used to identify more than 50 metabolites. The intracellular concentrations of over 40 metabolites were estimated from the (1)H NMR spectra of extracts prepared by four extraction methods: perchloric acid, methanol/water, methanol/chloroform/water, and methanol alone. The metabolites quantified included: the majority of the biological alpha-amino acids; 4-aminobutyric acid; mono-, di- and tri-carboxylic acids; nucleotides; polyamines; myo-inositol; and phosphocholine and phosphoethanolamine. The parasites also contained a significant concentration (up to 12 mM) of the exogenous buffering agent, HEPES. Although the metabolite profiles obtained with each extraction method were broadly similar, perchloric acid was found to have significant advantages over the other extraction media.
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Affiliation(s)
- Rongwei Teng
- Biochemistry and Molecular Biology, The Australian National University, Canberra, ACT, Australia
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42
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Spillman NJ, Allen RJW, Kirk K. Acid extrusion from the intraerythrocytic malaria parasite is not via a Na(+)/H(+) exchanger. Mol Biochem Parasitol 2008; 162:96-9. [PMID: 18675853 DOI: 10.1016/j.molbiopara.2008.07.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/02/2008] [Accepted: 07/04/2008] [Indexed: 11/16/2022]
Abstract
The intraerythrocytic malaria parasite, Plasmodium falciparum maintains an intracellular pH (pH(i)) of around 7.3. If subjected to an experimentally imposed acidification the parasite extrudes H(+), thereby undergoing a pH(i) recovery. In a recent study, Bennett et al. [Bennett TN, Patel J, Ferdig MT, Roepe PD. P. falciparum Na(+)/H(+) exchanger activity and quinine resistance. Mol Biochem Parasitol 2007;153:48-58] used the H(+) ionophore nigericin, in conjunction with an acidic medium, to acidify the parasite cytosol, and then used bovine serum albumin (BSA) to scavenge the nigericin from the parasite membrane. The ensuing Na(+)-dependent pH(i) recovery, seen following an increase in the extracellular pH, was attributed to a plasma membrane Na(+)/H(+) exchanger. This is at odds with previous reports that the primary H(+) extrusion mechanism in the parasite is a plasma membrane V-type H(+)-ATPase. Here we present evidence that the Na(+)-dependent efflux of H(+) from parasites acidified using nigericin/BSA is attributable to Na(+)/H(+) exchange via residual nigericin remaining in the parasite plasma membrane, rather than to endogenous transporter activity.
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Affiliation(s)
- Natalie J Spillman
- Biochemistry and Molecular Biology, School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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44
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Lehane AM, Hayward R, Saliba KJ, Kirk K. A verapamil-sensitive chloroquine-associated H+ leak from the digestive vacuole in chloroquine-resistant malaria parasites. J Cell Sci 2008; 121:1624-32. [PMID: 18445688 DOI: 10.1242/jcs.016758] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chloroquine resistance in the malaria parasite Plasmodium falciparum has made malaria increasingly difficult to control. Chloroquine-resistant parasites accumulate less chloroquine than their chloroquine-sensitive counterparts; however, the mechanism underlying this remains unclear. The primary site of accumulation and antimalarial action of chloroquine is the internal acidic digestive vacuole of the parasite, the acidity of which is maintained by inwardly-directed H+ pumps, working against the (outward) leak of H+. In this study we have investigated the leak of H+ from the digestive vacuole of the parasite by monitoring the alkalinisation of the vacuole following inhibition of the H+-pumping V-type ATPase by concanamycin A. The rates of alkalinisation observed in three chloroquine-resistant strains were two- to fourfold higher than those measured in three chloroquine-sensitive strains. On addition of chloroquine there was a dramatic increase in the rate of alkalinisation in the chloroquine-resistant strains, whereas chloroquine caused the rate of alkalinisation to decrease in the chloroquine-sensitive strains. The chloroquine-associated increase in the rate of alkalinisation seen in chloroquine-resistant parasites was inhibited by the chloroquine-resistance reversal agent verapamil. The data are consistent with the hypothesis that in chloroquine-resistant parasites chloroquine effluxes from the digestive vacuole, in association with H+, via a verapamil-sensitive pathway.
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Affiliation(s)
- Adele M Lehane
- School of Biochemistry and Molecular Biology, The Australian National University, Canberra ACT 0200, Australia
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Miranda K, de Souza W, Plattner H, Hentschel J, Kawazoe U, Fang J, Moreno SNJ. Acidocalcisomes in Apicomplexan parasites. Exp Parasitol 2008; 118:2-9. [PMID: 17761167 DOI: 10.1016/j.exppara.2007.07.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 07/19/2007] [Accepted: 07/21/2007] [Indexed: 10/23/2022]
Abstract
Acidocalcisomes are acidic calcium stores found in diverse organisms, being conserved from bacteria to man. They posses an acidic matrix that contains several cations bound to phosphates, mainly present in the form of short and long polyphosphate chains. Their matrix is acidified through the action of proton pumps such as a vacuolar proton ATPase and a vacuolar proton pyrophosphatase. The calcium uptake occurs through a Ca2+/H+ counter transporting ATPase located in the membrane of the organelle. Acidocalcisomes have been identified in a variety of microorganisms, including Apicomplexan parasites such as Plasmodium and Eimeria species, and in Toxoplasma gondii. In this paper, we review the structural, biochemical and physiological aspects of acidocalcisomes in Apicomplexan parasites and discuss their functional roles in the maintenance of intracellular ion homeostasis.
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Affiliation(s)
- Kildare Miranda
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, 350 Paul D. Coverdell Center, University of Georgia, Athens, GA 30602, USA
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Garcia CRS, de Azevedo MF, Wunderlich G, Budu A, Young JA, Bannister L. Plasmodium in the postgenomic era: new insights into the molecular cell biology of malaria parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:85-156. [PMID: 18544493 DOI: 10.1016/s1937-6448(07)66003-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this review, we bring together some of the approaches toward understanding the cellular and molecular biology of Plasmodium species and their interaction with their host red blood cells. Considerable impetus has come from the development of new methods of molecular genetics and bioinformatics, and it is important to evaluate the wealth of these novel data in the context of basic cell biology. We describe how these approaches are gaining valuable insights into the parasite-host cell interaction, including (1) the multistep process of red blood cell invasion by the merozoite; (2) the mechanisms by which the intracellular parasite feeds on the red blood cell and exports parasite proteins to modify its cytoadherent properties; (3) the modulation of the cell cycle by sensing the environmental tryptophan-related molecules; (4) the mechanism used to survive in a low Ca(2+) concentration inside red blood cells; (5) the activation of signal transduction machinery and the regulation of intracellular calcium; (6) transfection technology; and (7) transcriptional regulation and genome-wide mRNA studies in Plasmodium falciparum.
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Affiliation(s)
- Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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Beraldo FH, Almeida FM, da Silva AM, Garcia CRS. Cyclic AMP and calcium interplay as second messengers in melatonin-dependent regulation of Plasmodium falciparum cell cycle. ACTA ACUST UNITED AC 2007; 170:551-7. [PMID: 16103224 PMCID: PMC2171486 DOI: 10.1083/jcb.200505117] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The host hormone melatonin increases cytoplasmic Ca(2+) concentration and synchronizes Plasmodium cell cycle (Hotta, C.T., M.L. Gazarini, F.H. Beraldo, F.P. Varotti, C. Lopes, R.P. Markus, T. Pozzan, and C.R. Garcia. 2000. Nat. Cell Biol. 2:466-468). Here we show that in Plasmodium falciparum melatonin induces an increase in cyclic AMP (cAMP) levels and cAMP-dependent protein kinase (PKA) activity (40 and 50%, respectively). When red blood cells infected with P. falciparum are treated with cAMP analogue adenosine 3',5'-cyclic monophosphate N6-benzoyl/PKA activator (6-Bz-cAMP) there is an alteration of the parasite cell cycle. This effect appears to depend on activation of PKA (abolished by the PKA inhibitors adenosine 3',5'-cyclic monophosphorothioate/8 Bromo Rp isomer, PKI [cell permeable peptide], and H89). An unexpected cross talk was found to exist between the cAMP and the Ca(2+)-dependent signaling pathways. The increases in cAMP by melatonin are inhibited by blocker of phospholipase C U73122, and addition of 6-Bz-cAMP increases cytosolic Ca(2+) concentration, through PKA activation. These findings suggest that in Plasmodium a highly complex interplay exists between the Ca(2+) and cAMP signaling pathways, but also that the control of the parasite cell cycle by melatonin requires the activation of both second messenger controlled pathways.
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Affiliation(s)
- Flávio H Beraldo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
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Downie MJ, Saliba KJ, Howitt SM, Bröer S, Kirk K. Transport of nucleosides across the Plasmodium falciparum parasite plasma membrane has characteristics of PfENT1. Mol Microbiol 2006; 60:738-48. [PMID: 16629674 DOI: 10.1111/j.1365-2958.2006.05125.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Like all parasitic protozoa, the human malaria parasite Plasmodium falciparum lacks the enzymes required for de novo synthesis of purines and it is therefore reliant upon the salvage of these compounds from the external environment. P. falciparum equilibrative nucleoside transporter 1 (PfENT1) is a nucleoside transporter that has been localized to the plasma membrane of the intraerythrocytic form of the parasite. In this study we have characterized the transport of purine and pyrimidine nucleosides across the plasma membrane of 'isolated' trophozoite-stage P. falciparum parasites and compared the transport characteristics of the parasite with those of PfENT1 expressed in Xenopus oocytes. The transport of nucleosides into the parasite: (i) was, in the case of adenosine, inosine and thymidine, very fast, equilibrating within a few seconds; (ii) was of low affinity [K(m) (adenosine) = 1.45 +/- 0.25 mM; K(m) (thymidine) = 1.11 +/- 0.09 mM]; and (iii) showed 'cross-competition' for adenosine, inosine and thymidine, but not cytidine. The kinetic characteristics of nucleoside transport in intact parasites matched very closely those of PfENT1 expressed in Xenopus oocytes [K(m) (adenosine) = 1.86 +/- 0.28 mM; K(m) (thymidine) = 1.33 +/- 0.17 mM]. Furthermore, PfENT1 transported adenosine, inosine and thymidine, with a cross-competition profile the same as that seen for isolated parasites. The data are consistent with PfENT1 serving as a major route for the uptake of nucleosides across the parasite plasma membrane.
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Affiliation(s)
- Megan J Downie
- School of Biochemistry and Molecular Biology, The Australian National University, Canberra ACT 0200, Australia
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Kirk K, Martin RE, Bröer S, Howitt SM, Saliba KJ. Plasmodium permeomics: membrane transport proteins in the malaria parasite. Curr Top Microbiol Immunol 2005; 295:325-56. [PMID: 16265897 DOI: 10.1007/3-540-29088-5_13] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Membrane transport proteins are integral membrane proteins that mediate the passage across the membrane bilayer of specific molecules and/or ions. Such proteins serve a diverse range of physiological roles, mediating the uptake of nutrients into cells, the removal of metabolic wastes and xenobiotics (including drugs), and the generation and maintenance of transmembrane electrochemical gradients. In this chapter we review the present state of knowledge of the membrane transport mechanisms underlying the cell physiology of the intraerythrocytic malaria parasite and its host cell, considering in particular physiological measurements on the parasite and parasitized erythrocyte, the annotation of transport proteins in the Plasmodium genome, and molecular methods used to analyze transport protein function.
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Affiliation(s)
- K Kirk
- School of Biochemistry and Molecular Biology, The Australian National University, 0200 Canberra, ACT, Australia.
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van Dooren GG, Marti M, Tonkin CJ, Stimmler LM, Cowman AF, McFadden GI. Development of the endoplasmic reticulum, mitochondrion and apicoplast during the asexual life cycle of Plasmodium falciparum. Mol Microbiol 2005; 57:405-19. [PMID: 15978074 DOI: 10.1111/j.1365-2958.2005.04699.x] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Plasmodium parasites are unicellular eukaryotes that undergo a series of remarkable morphological transformations during the course of a multistage life cycle spanning two hosts (mosquito and human). Relatively little is known about the dynamics of cellular organelles throughout the course of these transformations. Here we describe the morphology of three organelles (endoplasmic reticulum, apicoplast and mitochondrion) through the human blood stages of the parasite life cycle using fluorescent reporter proteins fused to organelle targeting sequences. The endoplasmic reticulum begins as a simple crescent-shaped organelle that develops into a perinuclear ring with two small protrusions, followed by transformation into an extensive reticulated network as the parasite enlarges. Similarly, the apicoplast and the mitochondrion grow from single, small, discrete organelles into highly branched structures in later-stage parasites. These branched structures undergo an ordered fission - apicoplast followed by mitochondrion - to create multiple daughter organelles that are apparently linked as pairs for packaging into daughter cells. This is the first in-depth examination of intracellular organelles in live parasites during the asexual life cycle of this important human pathogen.
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Affiliation(s)
- Giel G van Dooren
- Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, VIC 3010, Australia
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