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Abstract
Plasmodium falciparum, the causative agent of malaria, completely remodels the infected human erythrocyte to acquire nutrients and to evade the immune system. For this process, the parasite exports more than 10% of all its proteins into the host cell cytosol, including the major virulence factor PfEMP1 (P. falciparum erythrocyte surface protein 1). This unusual protein trafficking system involves long-known parasite-derived membranous structures in the host cell cytosol, called Maurer's clefts. However, the genesis, role, and function of Maurer's clefts remain elusive. Similarly unclear is how proteins are sorted and how they are transported to and from these structures. Recent years have seen a large increase of knowledge but, as yet, no functional model has been established. In this perspective we review the most important findings and conclude with potential possibilities to shed light into the enigma of Maurer's clefts. Understanding the mechanism and function of these structures, as well as their involvement in protein export in P. falciparum, might lead to innovative control strategies and might give us a handle with which to help to eliminate this deadly parasite.
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The N-terminal segment of Plasmodium falciparum SURFIN4.1 is required for its trafficking to the red blood cell cytosol through the endoplasmic reticulum. Parasitol Int 2013; 62:215-29. [DOI: 10.1016/j.parint.2012.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 11/24/2022]
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3
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Glushakova S, Lizunov V, Blank PS, Melikov K, Humphrey G, Zimmerberg J. Cytoplasmic free Ca2+ is essential for multiple steps in malaria parasite egress from infected erythrocytes. Malar J 2013; 12:41. [PMID: 23363708 PMCID: PMC3564835 DOI: 10.1186/1475-2875-12-41] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 01/19/2013] [Indexed: 11/25/2022] Open
Abstract
Background Egress of Plasmodium falciparum, from erythrocytes at the end of its asexual cycle and subsequent parasite invasion into new host cells, is responsible for parasite dissemination in the human body. The egress pathway is emerging as a coordinated multistep programme that extends in time for tens of minutes, ending with rapid parasite extrusion from erythrocytes. While the Ca2+ regulation of the invasion of P. falciparum in erythrocytes is well established, the role of Ca2+ in parasite egress is poorly understood. This study analysed the involvement of cytoplasmic free Ca2+ in infected erythrocytes during the multistep egress programme of malaria parasites. Methods Live-cell fluorescence microscopy was used to image parasite egress from infected erythrocytes, assessing the effect of drugs modulating Ca2+ homeostasis on the egress programme. Results A steady increase in cytoplasmic free Ca2+ is found to precede parasite egress. This increase is independent of extracellular Ca2+ for at least the last two hours of the cycle, but is dependent upon Ca2+ release from internal stores. Intracellular BAPTA chelation of Ca2+ within the last 45 minutes of the cycle inhibits egress prior to parasitophorous vacuole swelling and erythrocyte membrane poration, two characteristic morphological transformations preceding parasite egress. Inhibitors of the parasite endoplasmic reticulum (ER) Ca2+-ATPase accelerate parasite egress, indicating that Ca2+ stores within the ER are sufficient in supporting egress. Markedly accelerated egress of apparently viable parasites was achieved in mature schizonts using Ca2+ ionophore A23187. Ionophore treatment overcomes the BAPTA-induced block of parasite egress, confirming that free Ca2+ is essential in egress initiation. Ionophore treatment of immature schizonts had an adverse effect inducing parasitophorous vacuole swelling and killing the parasites within the host cell. Conclusions The parasite egress programme requires intracellular free Ca2+ for egress initiation, vacuole swelling, and host cell cytoskeleton digestion. The evidence that parasitophorous vacuole swelling, a stage of unaffected egress, is dependent upon a rise in intracellular Ca2+ suggests a mechanism for ionophore-inducible egress and a new target for Ca2+ in the programme liberating parasites from the host cell. A regulatory pathway for egress that depends upon increases in intracellular free Ca2+ is proposed.
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Affiliation(s)
- Svetlana Glushakova
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
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Azouzi S, El Kirat K, Morandat S. The potent antimalarial drug cyclosporin A preferentially destabilizes sphingomyelin-rich membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:1960-1965. [PMID: 19697916 DOI: 10.1021/la902580w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Cyclosporin A (CsA) is a hydrophobic cyclic peptide produced by a fungus. CsA is widely used as an immunosuppressive agent to inhibit the rejection of transplanted organs. CsA also exhibits an antiparasitic activity against Plasmodium, the microorganism responsible for malaria disease. This antimalarial activity is not completely understood yet. In this study, we have used Langmuir monolayers and atomic force microscopy to investigate the interaction of CsA with different lipids: phosphatidylcholines with different molecular packing, cholesterol, and sphingomyelin. We have shown that CsA inserts in all kinds of lipid monolayers but it has a marked preference for sphingomyelin monolayers. This preferential insertion of CsA within sphingomyelin-enriched membranes could explain the antimalarial activity of CsA. Indeed, the parasites need to produce a membrane network inside the erythrocytes, which allows for their proper development/multiplication by exchanging nutrients with the external medium. This membrane network is particularly enriched in sphingomyelin, so the preferential insertion of CsA in these bilayers may destabilize them, thereby inhibiting the development of the parasite.
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Affiliation(s)
- Slim Azouzi
- Laboratoire de Génie Enzymatique et Cellulaire, CNRS UMR 6022, 60205 Compiègne Cedex, France
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Proteins of the Plasmodium falciparum two transmembrane Maurer’s cleft protein family, PfMC-2TM, and the 130 kDa Maurer’s cleft protein define different domains of the infected erythrocyte intramembranous network. Parasitol Res 2009; 104:875-91. [DOI: 10.1007/s00436-008-1270-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Accepted: 11/07/2008] [Indexed: 10/21/2022]
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6
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Struck NS, Herrmann S, Schmuck-Barkmann I, de Souza Dias S, Haase S, Cabrera AL, Treeck M, Bruns C, Langer C, Cowman AF, Marti M, Spielmann T, Gilberger TW. Spatial dissection of the cis- and trans-Golgi compartments in the malaria parasite Plasmodium falciparum. Mol Microbiol 2008; 67:1320-30. [DOI: 10.1111/j.1365-2958.2008.06125.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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7
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Hanssen E, Sougrat R, Frankland S, Deed S, Klonis N, Lippincott-Schwartz J, Tilley L. Electron tomography of the Maurer's cleft organelles of Plasmodium falciparum-infected erythrocytes reveals novel structural features. Mol Microbiol 2007; 67:703-18. [PMID: 18067543 DOI: 10.1111/j.1365-2958.2007.06063.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
During intraerythrocytic development, the human malaria parasite, Plasmodium falciparum, establishes membrane-bound compartments, known as Maurer's clefts, outside the confines of its own plasma membrane. The Maurer's compartments are thought to be a crucial component of the machinery for protein sorting and trafficking; however, their ultrastructure is only partly defined. We have used electron tomography to image Maurer's clefts of 3D7 strain parasites. The compartments are revealed as flattened structures with a translucent lumen and a more electron-dense coat. They display a complex and convoluted morphology, and some regions are modified with surface nodules, each with a circular cross-section of approximately 25 nm. Individual 25 nm vesicle-like structures are also seen in the erythrocyte cytoplasm and associated with the red blood cell membrane. The Maurer's clefts are connected to the red blood cell membrane by regions with extended stalk-like profiles. Immunogold labelling with specific antibodies confirms differential labelling of the Maurer's clefts and the parasitophorous vacuole and erythrocyte membranes. Spot fluorescence photobleaching was used to demonstrate the absence of a lipid continuum between the Maurer's clefts and parasite membranes and the host plasma membrane.
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Affiliation(s)
- Eric Hanssen
- Department of Biochemistry and Centre of Excellence for Coherent X-ray Science, La Troube University, Melbourne, Victoria 3086, Australia
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Glushakova S, Yin D, Li T, Zimmerberg J. Membrane transformation during malaria parasite release from human red blood cells. Curr Biol 2006; 15:1645-50. [PMID: 16169486 DOI: 10.1016/j.cub.2005.07.067] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Revised: 07/22/2005] [Accepted: 07/22/2005] [Indexed: 10/25/2022]
Abstract
Three opposing pathways are proposed for the release of malaria parasites from infected erythrocytes: coordinated rupture of the two membranes surrounding mature parasites; fusion of erythrocyte and parasitophorus vacuolar membranes (PVM); and liberation of parasites enclosed within the vacuole from the erythrocyte followed by PVM disintegration. Rupture by cell swelling should yield erythrocyte ghosts; membrane fusion is inhibited by inner-leaflet amphiphiles of positive intrinsic curvature, which contrariwise promote membrane rupture; and without protease inhibitors, parasites would leave erythrocytes packed within the vacuole. Therefore, we visualized erythrocytes releasing P. falciparum using fluorescent microscopy of differentially labeled membranes. Release did not yield erythrocyte ghosts, positive-curvature amphiphiles did not inhibit release but promoted it, and release of packed merozoites was shown to be an artifact. Instead, two sequential morphological stages preceded a convulsive rupture of membranes and rapid radial discharge of separated merozoites, leaving segregated internal membrane fragments and plasma membrane vesicles or blebs at the sites of parasite egress. These results, together with the modulation of release by osmotic stress, suggest a pathway of parasite release that features a biochemically altered erythrocyte membrane that folds after pressure-driven rupture of membranes.
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Affiliation(s)
- Svetlana Glushakova
- Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Wickert H, Göttler W, Krohne G, Lanzer M. Maurer's cleft organization in the cytoplasm of plasmodium falciparum-infected erythrocytes: new insights from three-dimensional reconstruction of serial ultrathin sections. Eur J Cell Biol 2005; 83:567-82. [PMID: 15679102 DOI: 10.1078/0171-9335-00432] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maurer's clefts are single-membrane-limited structures in the cytoplasm of erythrocytes infected with the human malarial parasite Plasmodium falciparum. The currently accepted model suggests that Maurer's clefts act as an intermediate compartment in protein transport processes from the parasite across the cytoplasm of the host cell to the erythrocyte surface, by receiving and delivering protein cargo packed in vesicles. This model is mainly based on two observations. Firstly, single-section electron micrographs have shown, within the cytoplasm of infected erythrocytes, stacks of long slender membranes in close vicinity to round membrane profiles considered to be vesicles. Secondly, proteins that are transported from the parasite to the erythrocyte surface as well as proteins facilitating the budding of vesicles have been found in association with Maurer's clefts. Verification of this model would be greatly assisted by a better understanding of the morphology, dimensions and origin of the Maurer's clefts. Here, we have generated and analyzed three-dimensional reconstructions of serial ultrathin sections covering segments of P. falciparum-infected erythrocytes of more than 1 microm thickness. Our results indicate that Maurer's clefts are heterogeneous in structure and size. We have found Maurer's clefts consisting of a single disk-shaped cisternae localized beneath the plasma membrane. In other examples, Maurer' clefts formed an extended membranous network that bridged most of the distance between the parasite and the plasma membrane of the host erythrocyte. Maurer's cleft membrane networks were composed of both branched membrane tubules and stacked disk-shaped membrane cisternae that eventually formed whorls. Maurer's clefts were visible in other cells as a loose membrane reticulum composed of scattered tubular and disk-shaped membrane profiles. We have not seen clearly discernable isolated vesicles in the analyzed erythrocyte segments suggesting that the current view of how proteins are transported within the Plasmodium-infected erythrocyte may need reconsideration.
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Affiliation(s)
- Hannes Wickert
- Division of Electron Microscopy Biocenter, University of Würzburg, Germany
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Labaied M, Dagan A, Dellinger M, Gèze M, Egée S, Thomas SL, Wang C, Gatt S, Grellier P. Anti-Plasmodium activity of ceramide analogs. Malar J 2004; 3:49. [PMID: 15588325 PMCID: PMC539285 DOI: 10.1186/1475-2875-3-49] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2004] [Accepted: 12/10/2004] [Indexed: 11/10/2022] Open
Abstract
Background Sphingolipids are key molecules regulating many essential functions in eukaryotic cells and ceramide plays a central role in sphingolipid metabolism. A sphingolipid metabolism occurs in the intraerythrocytic stages of Plasmodium falciparum and is associated with essential biological processes. It constitutes an attractive and potential target for the development of new antimalarial drugs. Methods The anti-Plasmodium activity of a series of ceramide analogs containing different linkages (amide, methylene or thiourea linkages) between the fatty acid part of ceramide and the sphingoid core was investigated in culture and compared to the sphingolipid analog PPMP (d,1-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol). This analog is known to inhibit the parasite sphingomyelin synthase activity and block parasite development by preventing the formation of the tubovesicular network that extends from the parasitophorous vacuole to the red cell membrane and delivers essential extracellular nutrients to the parasite. Results Analogs containing methylene linkage showed a considerably higher anti-Plasmodium activity (IC50 in the low nanomolar range) than PPMP and their counterparts with a natural amide linkage (IC50 in the micromolar range). The methylene analogs blocked irreversibly P. falciparum development leading to parasite eradication in contrast to PPMP whose effect is cytostatic. A high sensitivity of action towards the parasite was observed when compared to their effect on the human MRC-5 cell growth. The toxicity towards parasites did not correlate with the inhibition by methylene analogs of the parasite sphingomyelin synthase activity and the tubovesicular network formation, indicating that this enzyme is not their primary target. Conclusions It has been shown that ceramide analogs were potent inhibitors of P. falciparum growth in culture. Interestingly, the nature of the linkage between the fatty acid part and the sphingoid core considerably influences the antiplasmodial activity and the selectivity of analogs when compared to their cytotoxicity on mammalian cells. By comparison with their inhibitory effect on cancer cell growth, the ceramide analogs might inhibit P. falciparum growth through modulation of the endogenous ceramide level.
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Affiliation(s)
- Mehdi Labaied
- USM0504 Biologie fonctionnelle des protozoaires, Département Régulations, Développement, Diversité Moléculaire, Muséum National d'Histoire Naturelle, Boite postale n°52, 61 rue Buffon, 75231 Paris Cedex 05, France
| | - Arie Dagan
- Department of Biochemistry, Hebrew University-Hadassah School of Medicine, P.O. Box 12272, Jerusalem, 91120, Israel
| | - Marc Dellinger
- USM0504 Biologie fonctionnelle des protozoaires, Département Régulations, Développement, Diversité Moléculaire, Muséum National d'Histoire Naturelle, Boite postale n°52, 61 rue Buffon, 75231 Paris Cedex 05, France
| | - Marc Gèze
- USM0504 Biologie fonctionnelle des protozoaires, Département Régulations, Développement, Diversité Moléculaire, Muséum National d'Histoire Naturelle, Boite postale n°52, 61 rue Buffon, 75231 Paris Cedex 05, France
| | - Stéphane Egée
- CNRS FRE 2775, Station biologique de Roscoff, 29682 Roscoff, France
| | - Serge L Thomas
- CNRS FRE 2775, Station biologique de Roscoff, 29682 Roscoff, France
| | - Chunbo Wang
- Department of Biochemistry, Hebrew University-Hadassah School of Medicine, P.O. Box 12272, Jerusalem, 91120, Israel
| | - Shimon Gatt
- Department of Biochemistry, Hebrew University-Hadassah School of Medicine, P.O. Box 12272, Jerusalem, 91120, Israel
| | - Philippe Grellier
- USM0504 Biologie fonctionnelle des protozoaires, Département Régulations, Développement, Diversité Moléculaire, Muséum National d'Histoire Naturelle, Boite postale n°52, 61 rue Buffon, 75231 Paris Cedex 05, France
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11
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Abstract
Malaria is the most serious and widespread parasitic disease of humans and is arguably the commonest disease of red blood cells (RBCs). Malaria has exerted a powerful effect on human evolution and selection for resistance has led to the appearance and persistence of a number of inherited diseases. After parasite invasion, RBCs are progressively and dramatically modified. New structures appear inside the RBC and novel parasite proteins are exported to the erythrocyte cytoplasm and membrane skeleton. Radical biochemical, morphological, and rheological alterations manifest as increased membrane rigidity, reduced cell deformability, and greater adhesiveness for the vascular endothelium and other blood cells. Numerous protein-protein interactions between the malaria-parasite and the host RBC are important for many aspects of parasite biology and the pathogenesis of malaria. In addition, there are many other parasite proteins located within the infected red cell and at the membrane skeleton, for which no precise functional roles have yet been elucidated. Sequencing and annotation of the complete genome of Plasmodium falciparum, the production of proteomic and transcriptomic profiles of parasites, and the development of a transfection system for the asexual stage of the parasite are all recent achievements that should advance understanding of the molecular mechanisms that underlie the parasite-induced functional alterations in red cells.
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Affiliation(s)
- Brian M Cooke
- Department of Microbiology, Monash University, Victoria 3800, Australia
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Bannister LH, Hopkins JM, Margos G, Dluzewski AR, Mitchell GH. Three-dimensional ultrastructure of the ring stage of Plasmodium falciparum: evidence for export pathways. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2004; 10:551-562. [PMID: 15525429 DOI: 10.1017/s1431927604040917] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2003] [Indexed: 05/24/2023]
Abstract
The three-dimensional structure of the Plasmodium falciparum ring stage has been explored by reconstruction from serial sections and stereoscopic examination of tilted sections. The ring-like light microscopic appearance is related to the shape and contents of the biconcave discoidal parasite at this stage, its thick perimeter containing most of the ribosomes and its thin center containing smooth membrane organelles. The shapes of rings vary between flat and curved cuplike forms. The rough endoplasmic reticulum is a branched network continuous with the nuclear envelope. Evidence for a simple Golgi complex is seen in the presence on the outer nuclear envelope of a locus of coated vesicle budding associated with a single membranous cisterna or cluster of smooth vesicles. In middle and late stage rings this complex migrates along an extension of the nuclear envelope continuous with the rough endoplasmic reticulum. Evidence is also presented for a mechanism of exporting membrane from the parasite into the parasitophorous vacuole membrane and beyond into the red blood cell, by means of double-membraned vesicle-based exocytosis.
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Affiliation(s)
- Lawrence Howard Bannister
- Department of Anatomy, Cell and Human Biology, Guy's, King's and St. Thomas' School of Biomedical Science, Guy's Hospital, London SE1 1UL, UK.
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13
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Hawthorne PL, Trenholme KR, Skinner-Adams TS, Spielmann T, Fischer K, Dixon MWA, Ortega MR, Anderson KL, Kemp DJ, Gardiner DL. A novel Plasmodium falciparum ring stage protein, REX, is located in Maurer’s clefts. Mol Biochem Parasitol 2004; 136:181-9. [PMID: 15481109 DOI: 10.1016/j.molbiopara.2004.03.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The asexual stages of the malaria parasite Plasmodium falciparum develop inside erythrocytes of the human host. Erythrocytes are highly specialized cells lacking organelles and trafficking machinery. The parasite must therefore establish its own transport system to export proteins and waste and import nutrients. A number of parasite-derived structures, implicated in trafficking, appear in the infected red blood cell at the late ring stage. We have identified a novel gene transcribed in ring stage parasites coding for a protein designated the ring exported protein, REX. REX is located in a red cell modification known as the Maurer's clefts, which are parasite induced structures implicated in trafficking of parasite proteins to the red blood cell surface. REX contains predicted coiled-coil regions and a region with similarity to a domain in vesicle-tethering proteins. REX persists in Maurer's clefts throughout the infection of the erythrocyte, where it may play a role in the biogenesis and/or function of this organelle.
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Sam-Yellowe TY, Florens L, Johnson JR, Wang T, Drazba JA, Le Roch KG, Zhou Y, Batalov S, Carucci DJ, Winzeler EA, Yates JR. A Plasmodium gene family encoding Maurer's cleft membrane proteins: structural properties and expression profiling. Genome Res 2004; 14:1052-9. [PMID: 15140830 PMCID: PMC419783 DOI: 10.1101/gr.2126104] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Upon invasion of the erythrocyte cell, the malaria parasite remodels its environment; in particular, it establishes a complex membrane network, which connects the parasitophorous vacuole to the host plasma membrane and is involved in protein transport and trafficking. We have identified a novel subtelomeric gene family in Plasmodium falciparum that encodes 11 transmembrane proteins localized to the Maurer's clefts. Using coimmunoprecipitation and shotgun proteomics, we were able to enrich specifically for these proteins and detect distinct peptides, allowing us to conclude that four to 10 products were present at a given time. Nearly all of the Pfmc-2tm genes are transcribed during the trophozoite stage; this narrow time frame of transcription overlaps with the specific stevor and rif genes that are differentially expressed during the erythrocyte cycle. The description of the structural properties of the proteins led us to manually reannotate published sequences, and to detect potentially homologous gene families in both P. falciparum and Plasmodium yoelii yoelii, where no orthologs were predicted uniquely based on sequence similarity. These basic proteins with two transmembrane domains belong to a larger superfamily, which includes STEVORs and RIFINs.
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Affiliation(s)
- Tobili Y Sam-Yellowe
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115, USA.
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15
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Kriek N, Tilley L, Horrocks P, Pinches R, Elford BC, Ferguson DJP, Lingelbach K, Newbold CI. Characterization of the pathway for transport of the cytoadherence-mediating protein, PfEMP1, to the host cell surface in malaria parasite-infected erythrocytes. Mol Microbiol 2003; 50:1215-27. [PMID: 14622410 DOI: 10.1046/j.1365-2958.2003.03784.x] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family of antigenically diverse proteins is expressed on the surface of human erythrocytes infected with the malaria parasite P. falciparum, and mediates cytoadherence to the host vascular endothelium. In this report, we show that export of PfEMP1 is slow and inefficient as it takes several hours to traffic newly synthesized proteins to the erythrocyte membrane. Upon removal by trypsin treatment, the surface-exposed population of PfEMP1 is not replenished during subsequent culture indicating that there is no cycling of PfEMP1 between the erythrocyte surface and an intracellular compartment. The role of Maurer's clefts as an intermediate sorting compartment in trafficking of PfEMP1 was investigated using immunoelectron microscopy and proteolytic digestion of streptolysin O-permeabilized parasitized erythrocytes. We show that PfEMP1 is inserted into the Maurer's cleft membrane with the C-terminal domain exposed to the erythrocyte cytoplasm, whereas the N-terminal domain is buried inside the cleft. Transfer of PfEMP1 to the erythrocyte surface appears to involve electron-lucent extensions of the Maurer's clefts. Thus, we have delineated some important aspects of the unusual trafficking mechanism for delivery of this critical parasite virulence factor to the erythrocyte surface.
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Affiliation(s)
- Neline Kriek
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, Headington, Oxford, OX3 9DS, UK
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Birago C, Albanesi V, Silvestrini F, Picci L, Pizzi E, Alano P, Pace T, Ponzi M. A gene-family encoding small exported proteins is conserved across Plasmodium genus. Mol Biochem Parasitol 2003; 126:209-18. [PMID: 12615320 DOI: 10.1016/s0166-6851(02)00275-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A gene-family, named sep, encoding small exported proteins conserved across Plasmodium species has been identified. SEP proteins (13-16 kDa) contain a predicted signal peptide at the NH(2)-terminus, an internal hydrophobic region and a polymorphic, low-complexity region at the carboxy-terminus. One member of the Plasmodium berghei family, Pbsep1, encodes an integral membrane protein expressed along the entire erythrocytic cycle. Immunolocalisation results indicated that PbSEP1 is targeted to the membrane of the parasitophorous vacuole up to the early phases of schizogony, while, in late schizonts, it re-locates in structures within the syncitium. After erythrocyte rupture, PbSEP1 is still detectable in free merozoites thus suggesting its involvement in the early steps of parasite invasion. Seven members of the sep-family in Plasmodium falciparum have been identified. Two of them correspond to previously reported gene sequences included in a family of early transcribed membrane proteins (etramp). Structural, functional and phylogenetic features of the sep family, shown in the present work, supercede this previous classification. PfSEP proteins are exported beyond the parasite membrane and translocated, early after invasion, to the host cell compartment in association with vesicle-like structures. Colocalisation results indicated that PfSEP-specific fluorescence overlaps, at the stage of trophozoite, with that of Pf332, a protein associated with Maurer's clefts, membranous structures in the cytosol of parasitised red blood cells, most probably involved in trafficking of parasite proteins. The specific signals necessary to direct SEP proteins to the vacuolar membrane in P. berghei or to the host cell compartment in P. falciparum remain to be determined.
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Affiliation(s)
- Cecilia Birago
- Laboratorio di Biologia Cellulare, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
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Haldar K, Mohandas N, Samuel BU, Harrison T, Hiller NL, Akompong T, Cheresh P. Protein and lipid trafficking induced in erythrocytes infected by malaria parasites. Cell Microbiol 2002; 4:383-95. [PMID: 12102685 DOI: 10.1046/j.1462-5822.2002.00204.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human malaria parasite Plasmodium falciparum develops in a parasitophorous vacuolar membrane (PVM) within the mature red cell and extensively modifies structural and antigenic properties of this host cell. Recent studies shed significant new, mechanistic perspective on the underlying processes. There is finally, definitive evidence that despite the absence of endocytosis, transmembrane proteins in the host red cell membrane are imported in to the PVM. These are not major erythrocyte proteins but components that reside in detergent resistant membrane (DRM) rafts in red cell membrane and are detected in rafts in the PVM. Disruption of either erythrocyte or vacuolar rafts is detrimental to infection suggesting that raft proteins and lipids are essential for the parasitization of the red cell. On secretory export of parasite proteins: an ER secretory signal (SS) sequence is required for protein secretion to the PV. Proteins carrying an additional plastid targeting sequence (PTS) are also detected in the PV but subsequently delivered to the plastid organelle within the parasite, suggesting that the PTS may have a second function as an endocytic sorting signal. A distinct but yet undefined peptidic motif underlies protein transport across the PVM to the red cell (although all of the published data does not yet fit this model). Further multiple exported proteins transit through secretory 'cleft' structures, suggesting that clefts may be sorting compartments assembled by the parasite in the red cell.
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Affiliation(s)
- Kasturi Haldar
- Department of Pathology, Northwestern University, 303 E. Chicago Avenue, Chicago, IL 60611, USA.
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18
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Azzouz N, Rauscher B, Gerold P, Cesbron-Delauw MF, Dubremetz JF, Schwarz RT. Evidence for de novo sphingolipid biosynthesis in Toxoplasma gondii. Int J Parasitol 2002; 32:677-84. [PMID: 12062486 DOI: 10.1016/s0020-7519(02)00009-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Glycolipids are important components of cellular membranes involved in various biological functions. In this report, we describe the identification of the de novo synthesis of glycosphingolipids by Toxoplasma gondii tachyzoites. Parasite-specific glycolipids were identified by metabolic labelling of parasites with tritiated serine and galactose. These glycolipids were characterised as sphingolipids based on the labelling protocol and their insensitivity towards alkaline treatment. Synthesis of parasite glycosphingolipids were inhibited by threo-phenyl-2-palmitoylamino-3-morpholino-1-propanol and L-cycloserine, two well-established inhibitors of de novo sphingolipid biosynthesis. The identified glycolipids were insensitive towards treatment with endoglycoceramidase II indicating that they might belong to globo-type glycosphingolipids. Taken together, we provide evidence for the first time that T. gondii is capable of synthesising glycosphingolipids de novo.
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Affiliation(s)
- Nahid Azzouz
- Medizinisches Zentrum für Hygiene und Medizinische Mikrobiologie, Philipps-Universität Marburg, Robert-Koch Strasse 17, 35037, Marburg, Germany
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19
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Nacer A, Berry L, Slomianny C, Mattei D. Plasmodium falciparum signal sequences: simply sequences or special signals? Int J Parasitol 2001; 31:1371-9. [PMID: 11566304 DOI: 10.1016/s0020-7519(01)00253-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The malaria parasite, Plasmodium falciparum, synthesises and exports several proteins inducing morphological and biochemical modifications of erythrocytes during the erythrocytic cycle. The protein trafficking machinery of the parasite is similar to that of other eukaryotic cells in several ways. However, some unusual features are also observed. The secretion of various polypeptides was inhibited when P. falciparum-infected erythrocytes were incubated with Brefeldin A. Immunoelectron microscopy studies revealed substantial morphological changes in the endoplasmic reticulum following exposure of parasitised erythrocytes to the drug. Immunofluorescence studies of Brefeldin A-treated parasites suggest that polypeptide sorting to different intracellular destinations begins at the endoplasmic reticulum. The parasite also secretes polypeptides by a Brefeldin A-insensitive route that bypasses the classical endoplasmic reticulum-Golgi complex pathway.
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Affiliation(s)
- A Nacer
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 1960, Institut Pasteur, 75724 Paris, France
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20
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Gerold P, Schwarz RT. Biosynthesis of glycosphingolipids de-novo by the human malaria parasite Plasmodium falciparum. Mol Biochem Parasitol 2001; 112:29-37. [PMID: 11166384 DOI: 10.1016/s0166-6851(00)00336-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Glycolipids are important components of cellular membranes involved in various biological functions. In this report we describe the identification of the de-novo synthesis of glycosphingolipids by intraerythrocytic, asexual stages of the malaria parasite, Plasmodium falciparum. Parasite-specific glycolipids were identified in organic solvent extracts of parasites metabolically labeled with tritiated serine and glucosamine and characterised as sphingolipids based on their insensitivity towards alkaline treatment. While the de-novo synthesis of parasite glycosphingolipids was affected by fumonisin B1, threo-PPMP, cyclo-serine and myriocin, these well established inhibitors of de-novo ceramide biosynthesis were unable to arrest the intraerythrocytic development of the parasites in culture.
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Affiliation(s)
- P Gerold
- Med. Zentrum für Hygiene und Med. Mikrobiologie, Philipps-Universität, Robert-Koch-Strasse 17, 35037 Marburg, Germany
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21
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Cooke BM, Mohandas N, Coppel RL. The malaria-infected red blood cell: structural and functional changes. ADVANCES IN PARASITOLOGY 2001; 50:1-86. [PMID: 11757330 PMCID: PMC7130133 DOI: 10.1016/s0065-308x(01)50029-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The asexual stage of malaria parasites of the genus Plasmodium invade red blood cells of various species including humans. After parasite invasion, red blood cells progressively acquire a new set of properties and are converted into more typical, although still simpler, eukaryotic cells by the appearance of new structures in the red blood cell cytoplasm, and new proteins at the red blood cell membrane skeleton. The red blood cell undergoes striking morphological alterations and its rheological properties are considerably altered, manifesting as red blood cells with increased membrane rigidity, reduced deformability and increased adhesiveness for a number of other cells including the vascular endothelium. Elucidation of the structural changes in the red blood cell induced by parasite invasion and maturation and an understanding of the accompanying functional alterations have the ability to considerably extend our knowledge of structure-function relationships in the normal red blood cell. Furthermore, interference with these interactions may lead to previously unsuspected means of reducing parasite virulence and may lead to the development of novel antimalarial therapeutics.
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Affiliation(s)
- B M Cooke
- Department of Microbiology, P.O. Box 53, Monash University, Victoria 3800, Australia
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22
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Bannister LH, Hopkins JM, Fowler RE, Krishna S, Mitchell GH. A brief illustrated guide to the ultrastructure of Plasmodium falciparum asexual blood stages. PARASITOLOGY TODAY (PERSONAL ED.) 2000; 16:427-33. [PMID: 11006474 DOI: 10.1016/s0169-4758(00)01755-5] [Citation(s) in RCA: 219] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Interpretation of the new information arising from the Plasmodium falciparum Genome Project requires a good working knowledge of the ultrastructure of the parasite; however many aspects of the morphology of this species remain obscure. Lawrence Bannister, John Hopkins and colleagues here give an illustrated overview of the three-dimensional (3-D) organization of the merozoite, ring, trophozoite and schizont stages of the parasite, based on available data that include 3-D reconstruc-tion from serial electron microscope sections. The review describes the chief organelles present in these stages, emphasizing the continuity of structure in addition to specialized, stage-specific features developed during the asexual erythrocytic cycle.
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Affiliation(s)
- L H Bannister
- Centre for Neuroscience, Hodgkin Building, Guy's, King's and St Thomas' Hospitals School of Basic Medical Science, KCL, Guy's Campus, SE1 1UL, London, UK.
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23
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Lauer S, VanWye J, Harrison T, McManus H, Samuel BU, Hiller NL, Mohandas N, Haldar K. Vacuolar uptake of host components, and a role for cholesterol and sphingomyelin in malarial infection. EMBO J 2000; 19:3556-64. [PMID: 10899110 PMCID: PMC313993 DOI: 10.1093/emboj/19.14.3556] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Erythrocytes, which are incapable of endocytosis or phagocytosis, can be infected by the malaria parasite Plasmodium falciparum. We find that a transmembrane protein (Duffy), glycosylphosphatidylinositol (GPI)-anchored and cytoplasmic proteins, associated with detergent-resistant membranes (DRMs) that are characteristic of microdomains in host cell membranes, are internalized by vacuolar parasites, while the major integral membrane and cytoskeletal proteins are not. The internalized host proteins and a plasmodial transmembrane resident parasitophorous vacuolar membrane (PVM) protein are detected in DRMs associated with vacuolar parasites. This is the first report of a host transmembrane protein being recruited into an apicomplexan vacuole and of the presence of vacuolar DRMs; it establishes that integral association does not preclude protein internalization into the P.FALCIPARUM: vacuole. Rather, as shown for Duffy, intracellular accumulation occurs at the same rate as that seen for a DRM-associated GPI-anchored protein. Furthermore, novel mechanisms regulated by the DRM lipids, sphingomyelin and cholesterol, mediate (i) the uptake of host DRM proteins and (ii) maintenance of the intracellular vacuole in the non-endocytic red cell, which may have implications for intracellular parasitism and pathogenesis.
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Affiliation(s)
- S Lauer
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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24
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Wiser MF, Grab DJ, Lanners HN. An alternative secretory pathway in Plasmodium: more questions than answers. NOVARTIS FOUNDATION SYMPOSIUM 2000; 226:199-211; discussion 211-4. [PMID: 10645547 DOI: 10.1002/9780470515730.ch14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The malaria parasite extensively modifies the host erythrocyte. Many of these modifications are mediated by proteins exported from the parasite and targeted to specific locations within the infected erythrocyte. However, little is known about how the parasite targets proteins to specific locations beyond its own plasma membrane. Treatment of infected erythrocytes with brefeldin A results in the accumulation of many exported Plasmodium proteins into a compartment distinct from the ER. Proteins destined for the host erythrocyte membrane, the parasitophorous vacuole or inclusions within the erythrocyte cytoplasm accumulate in this novel compartment, and co-localization studies indicate that there is a single compartment per parasite. Exported proteins only accumulate in this novel compartment if brefeldin A treatment is concurrent with their synthesis. This novel compartment is probably a membrane-bound organelle located at the parasite periphery, and may be the first step in an alternative secretory pathway that specializes in the export of proteins into the host cell. Such an alternative secretory pathway raises questions about how exported proteins are differentially targeted to this novel organelle versus the ER and the fate of exported proteins after this novel organelle.
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Affiliation(s)
- M F Wiser
- Department of Tropical Medicine and Parasitology, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA
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25
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Ming M, VanWye J, Janse CJ, Waters AP, Haldar K. Gene organization of rab6, a marker for the novel Golgi of Plasmodium. Mol Biochem Parasitol 1999; 100:217-22. [PMID: 10391383 DOI: 10.1016/s0166-6851(99)00039-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- M Ming
- Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305, USA.
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26
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Wiser MF, Lanners HN, Bafford RA. Export of proteins via a novel secretory pathway. PARASITOLOGY TODAY (PERSONAL ED.) 1999; 15:194-8. [PMID: 10322353 DOI: 10.1016/s0169-4758(99)01440-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The intraerythrocytic location of the malaria parasite necessitates modification of the host cell. These alterations are mediated either directly or indirectly by parasite proteins exported to specific compartments within the host cell. However, little is known about how the parasite specifically targets proteins to locations beyond its plasma membrane. Mark Wiser, Norbert Lanners and Richard Bafford here propose an alternative secretory pathway for the export of parasite proteins into the host erythrocyte. The first step of this pathway is probably an endoplasmic reticulum (ER)-like organelle that is distinct from the normal ER. Possible mechanisms of protein trafficking in the infected erythrocyte are also discussed. The proposed ER-like organelle and alternative secretory pathway raise many questions about the cell biology of protein export and trafficking in Plasmodium.
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Affiliation(s)
- M F Wiser
- Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, 1501 Canal Street, New Orleans, LA 70112,
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