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Kalkan BM, Baykal AT, Cicek E, Acilan C. Comprehensive proteomics analysis reveals novel Nek2-regulated pathways and therapeutic targets in cancer. Biochem Biophys Res Commun 2024; 734:150779. [PMID: 39368370 DOI: 10.1016/j.bbrc.2024.150779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Revised: 09/23/2024] [Accepted: 09/30/2024] [Indexed: 10/07/2024]
Abstract
The mitotic kinase Nek2, often overexpressed in various cancers, plays a pivotal role in key cellular processes like the cell cycle, proliferation, and drug resistance. As a result, targeting Nek2 has become an appealing strategy for cancer therapy. To gain a comprehensive understanding of the cellular changes associated with Nek2 activity modulation, we performed a global proteomics analysis using LC-MS/MS. Through bioinformatics tools, we identified molecular pathways that are differentially regulated in cancer cells with Nek2 overexpression or depletion. Of the 1815 proteins identified, 358 exceeded the 20 % significance threshold. By integrating LC-MS/MS data with cancer patient datasets, we observed a strong correlation between Nek2 expression and the levels of KIF20B and RRM1. Silencing Nek2 led to a significant reduction in KIF20B and RRM1 protein levels, and potential phosphorylation sites for these proteins by Nek2 were identified. In summary, our data suggests that KIF20B and RRM1 are promising therapeutic targets, either independently or alongside Nek2 inhibitors, to improve clinical outcomes. Further analyses are necessary to fully understand Nek2's interactions with these proteins and their clinical relevance.
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Affiliation(s)
- Batuhan Mert Kalkan
- Koç University, Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey
| | - Ahmet Tarik Baykal
- Department of Medical Biochemistry, School of Medicine, Acibadem University, Istanbul, Turkey
| | - Enes Cicek
- Koç University, Graduate School of Health Sciences, Istanbul, Turkey
| | - Ceyda Acilan
- Koç University, Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey; Koç University, School of Medicine, Istanbul, Turkey.
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2
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Expression Analysis of Genes Involved in Transport Processes in Mice with MPTP-Induced Model of Parkinson’s Disease. Life (Basel) 2022; 12:life12050751. [PMID: 35629417 PMCID: PMC9146539 DOI: 10.3390/life12050751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 11/30/2022] Open
Abstract
Processes of intracellular and extracellular transport play one of the most important roles in the functioning of cells. Changes to transport mechanisms in a neuron can lead to the disruption of many cellular processes and even to cell death. It was shown that disruption of the processes of vesicular, axonal, and synaptic transport can lead to a number of diseases of the central nervous system, including Parkinson’s disease (PD). Here, we studied changes in the expression of genes whose protein products are involved in the transport processes (Snca, Drd2, Rab5a, Anxa2, and Nsf) in the brain tissues and peripheral blood of mice with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced models of PD. We detected changes in the expressions of Drd2, Anxa2, and Nsf at the earliest modeling stages. Additionally, we have identified conspicuous changes in the expression level of Anxa2 in the striatum and substantia nigra of mice with MPTP-induced models of PD in its early stages. These data clearly suggest the involvement of protein products in these genes in the earliest stages of the pathogenesis of PD.
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3
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A Phosphoinositide-Binding Protein Acts in the Trafficking Pathway of Hemoglobin in the Malaria Parasite Plasmodium falciparum. mBio 2022; 13:e0323921. [PMID: 35038916 PMCID: PMC8764524 DOI: 10.1128/mbio.03239-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Phosphoinositide lipids play key roles in a variety of processes in eukaryotic cells, but our understanding of their functions in the malaria parasite Plasmodium falciparum is still very much limited. To gain a deeper comprehension of the roles of phosphoinositides in this important pathogen, we attempted gene inactivation for 24 putative effectors of phosphoinositide metabolism. Our results reveal that 79% of the candidates are refractory to genetic deletion and are therefore potentially essential for parasite growth. Inactivation of the gene coding for a Plasmodium-specific putative phosphoinositide-binding protein, which we named PfPX1, results in a severe growth defect. We show that PfPX1 likely binds phosphatidylinositol-3-phosphate and that it localizes to the membrane of the digestive vacuole of the parasite and to vesicles filled with host cell cytosol and labeled with endocytic markers. Critically, we provide evidence that it is important in the trafficking pathway of hemoglobin from the host erythrocyte to the digestive vacuole. Finally, inactivation of PfPX1 renders parasites resistant to artemisinin, the frontline antimalarial drug. Globally, the minimal redundancy in the putative phosphoinositide proteins uncovered in our work supports that targeting this pathway has potential for antimalarial drug development. Moreover, our identification of a phosphoinositide-binding protein critical for the trafficking of hemoglobin provides key insight into this essential process. IMPORTANCE Malaria represents an enormous burden for a significant proportion of humanity, and the lack of vaccines and problems with drug resistance to all antimalarials demonstrate the need to develop new therapeutics. Inhibitors of phosphoinositide metabolism are currently being developed as antimalarials but our understanding of this biological pathway is incomplete. The malaria parasite lives inside human red blood cells where it imports hemoglobin to cover some of its nutritional needs. In this work, we have identified a phosphoinositide-binding protein that is important for the transport of hemoglobin in the parasite. Inactivation of this protein decreases the ability of the parasite to proliferate. Our results have therefore identified a potential new target for antimalarial development.
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4
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Bennink S, Pradel G. Vesicle dynamics during the egress of malaria gametocytes from the red blood cell. Mol Biochem Parasitol 2021; 243:111372. [PMID: 33961918 DOI: 10.1016/j.molbiopara.2021.111372] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/16/2021] [Accepted: 05/03/2021] [Indexed: 01/09/2023]
Abstract
Malaria parasites are obligate intracellular pathogens that live in human red blood cells harbored by a parasitophorous vacuole. The parasites need to exit from the red blood cell to continue life-cycle progression and ensure human-to-mosquito transmission. Two types of blood stages are able to lyse the enveloping red blood cell to mediate egress, the merozoites and the gametocytes. The intraerythrocytic parasites exit the red blood cell via an inside-out mode during which the membrane of the parasitophorous vacuole ruptures prior to the red blood cell membrane. Membrane rupture is initiated by the exocytosis of specialized secretory vesicles following the perception of egress triggers. The molecular mechanisms of red blood cell egress have particularly been studied in malaria gametocytes. Upon activation by external factors, gametocytes successively discharge at least two types of vesicles, the osmiophilic bodies needed to rupture the parasitophorous vacuole membrane and recently identified egress vesicles that are important for the perforation of the erythrocyte membrane. In recent years, important components of the signaling cascades leading to red blood cell egress have been investigated and several proteins of the osmiophilic bodies have been identified. We here report on the newest findings on the egress of gametocytes from the red blood cell. We further focus on the content and function of the egress-related vesicles and discuss the molecular machinery that might drive vesicle discharge.
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Affiliation(s)
- Sandra Bennink
- Division of Cellular and Applied Infection Biology, Institute of Biology 2, RWTH Aachen University, Aachen, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, Institute of Biology 2, RWTH Aachen University, Aachen, Germany.
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5
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Detection of the in vitro modulation of Plasmodium falciparum Arf1 by Sec7 and ArfGAP domains using a colorimetric plate-based assay. Sci Rep 2020; 10:4193. [PMID: 32144363 PMCID: PMC7061341 DOI: 10.1038/s41598-020-61101-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/09/2019] [Indexed: 11/18/2022] Open
Abstract
The regulation of human Arf1 GTPase activity by ArfGEFs that stimulate GDP/GTP exchange and ArfGAPs that mediate GTP hydrolysis has attracted attention for the discovery of Arf1 inhibitors as potential anti-cancer agents. The malaria parasite Plasmodium falciparum encodes a Sec7 domain-containing protein - presumably an ArfGEF - and two putative ArfGAPs, as well as an Arf1 homologue (PfArf1) that is essential for blood-stage parasite viability. However, ArfGEF and ArfGAP-mediated activation/deactivation of PfArf1 has not been demonstrated. In this study, we established an in vitro colorimetric microtiter plate-based assay to detect the activation status of truncated human and P. falciparum Arf1 and used it to demonstrate the activation of both proteins by the Sec7 domain of ARNO, their deactivation by the GAP domain of human ArfGAP1 and the inhibition of the respective reactions by the compounds SecinH3 and QS11. In addition, we found that the GAP domains of both P. falciparum ArfGAPs have activities equivalent to that of human ArfGAP1, but are insensitive to QS11. Library screening identified a novel inhibitor which selectively inhibits one of the P. falciparum GAP domains (IC50 4.7 µM), suggesting that the assay format is suitable for screening compound collections for inhibitors of Arf1 regulatory proteins.
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6
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Ebrahimzadeh Z, Mukherjee A, Crochetière MÈ, Sergerie A, Amiar S, Thompson LA, Gagnon D, Gaumond D, Stahelin RV, Dacks JB, Richard D. A pan-apicomplexan phosphoinositide-binding protein acts in malarial microneme exocytosis. EMBO Rep 2019; 20:e47102. [PMID: 31097469 PMCID: PMC6549027 DOI: 10.15252/embr.201847102] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 03/28/2019] [Accepted: 04/12/2019] [Indexed: 11/09/2022] Open
Abstract
Invasion of human red blood cells by the malaria parasite Plasmodium falciparum is an essential step in the development of the disease. Consequently, the molecular players involved in host cell invasion represent important targets for inhibitor design and vaccine development. The process of merozoite invasion is a succession of steps underlined by the sequential secretion of the organelles of the apical complex. However, little is known with regard to how their contents are exocytosed. Here, we identify a phosphoinositide-binding protein conserved in apicomplexan parasites and show that it is important for the attachment and subsequent invasion of the erythrocyte by the merozoite. Critically, removing the protein from its site of action by knock sideways preferentially prevents the secretion of certain types of micronemes. Our results therefore provide evidence for a role of phosphoinositide lipids in the malaria invasion process and provide further insight into the secretion of microneme organelle populations, which is potentially applicable to diverse apicomplexan parasites.
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Affiliation(s)
- Zeinab Ebrahimzadeh
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Angana Mukherjee
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Marie-Ève Crochetière
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Audrey Sergerie
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Souad Amiar
- Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
| | - L Alexa Thompson
- Division of Infectious Disease, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Dominic Gagnon
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - David Gaumond
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Robert V Stahelin
- Department of Medicinal Chemistry and Molecular Pharmacology and the Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
| | - Joel B Dacks
- Division of Infectious Disease, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Dave Richard
- Centre de Recherche en Infectiologie, CRCHU de Québec-Université Laval, Québec, QC, Canada
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7
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Mehnert AK, Simon CS, Guizetti J. Immunofluorescence staining protocol for STED nanoscopy of Plasmodium-infected red blood cells. Mol Biochem Parasitol 2019; 229:47-52. [PMID: 30831155 DOI: 10.1016/j.molbiopara.2019.02.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 02/20/2019] [Accepted: 02/25/2019] [Indexed: 12/12/2022]
Abstract
Immunofluorescence staining is the key technique for visualizing organization of endogenous cellular structures in single cells. Labeling and imaging of blood stage Plasmodium falciparum has always been challenging since it is a small intracellular parasite. A widely-used standard for parasite immunofluorescence is fixation in suspension with addition of minute amounts of glutaraldehyde to the paraformaldehyde-based solution. While this maintains red blood cell integrity, it has been postulated that antigenicity of the parasite proteins was, if at all, only slightly reduced. Here we show the deleterious effect that even these small quantities of glutaraldehyde can have on immunofluorescence staining quality and present an alternative cell seeding protocol that allows fixation with only paraformaldehyde. The highly improved signal intensity and staining efficiency enabled us to carry out RescueSTED nanoscopy on microtubules and nuclear pores and describe their organization in greater detail throughout the blood stage cycle.
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Affiliation(s)
- Ann-Kathrin Mehnert
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Caroline Sophie Simon
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Julien Guizetti
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
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8
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Thériault C, Richard D. Characterization of a putative Plasmodium falciparum SAC1 phosphoinositide-phosphatase homologue potentially required for survival during the asexual erythrocytic stages. Sci Rep 2017; 7:12710. [PMID: 28983103 PMCID: PMC5629215 DOI: 10.1038/s41598-017-12762-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 09/15/2017] [Indexed: 12/13/2022] Open
Abstract
Despite marked reductions in morbidity and mortality in the last ten years, malaria still takes a tremendous toll on human populations throughout tropical and sub-tropical regions of the world. The absence of an effective vaccine and resistance to most antimalarial drugs available demonstrate the urgent need for new intervention strategies. Phosphoinositides are a class of lipids with critical roles in numerous processes and their specific subcellular distribution, generated through the action of kinases and phosphatases, define organelle identity in a wide range of eukaryotic cells. Recent studies have highlighted important functions of phosphoinositide kinases in several parts of the Plasmodium lifecycle such as hemoglobin endocytosis and cytokinesis during the erythrocytic stage however, nothing is known with regards to the parasite's putative phosphoinositide phosphatases. We present the identification and initial characterization of a putative homologue of the SAC1 phosphoinositide phosphatase family. Our results show that the protein is expressed throughout the asexual blood stages and that it localises to the endoplasmic reticulum and potentially to the Golgi apparatus. Furthermore, conditional knockdown and knockout studies suggest that a minimal amount of the protein are likely required for survival during the erythrocytic cycle.
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Affiliation(s)
- Catherine Thériault
- Centre de recherche en infectiologie du CHU de Québec-Université Laval, Quebec City, Quebec, Canada
| | - Dave Richard
- Centre de recherche en infectiologie du CHU de Québec-Université Laval, Quebec City, Quebec, Canada.
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9
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Malaria Parasite Proteins and Their Role in Alteration of the Structure and Function of Red Blood Cells. ADVANCES IN PARASITOLOGY 2015; 91:1-86. [PMID: 27015947 DOI: 10.1016/bs.apar.2015.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Malaria, caused by Plasmodium spp., continues to be a major threat to human health and a significant cause of socioeconomic hardship in many countries. Almost half of the world's population live in malaria-endemic regions and many of them suffer one or more, often life-threatening episodes of malaria every year, the symptoms of which are attributable to replication of the parasite within red blood cells (RBCs). In the case of Plasmodium falciparum, the species responsible for most malaria-related deaths, parasite replication within RBCs is accompanied by striking alterations to the morphological, biochemical and biophysical properties of the host cell that are essential for the parasites' survival. To achieve this, the parasite establishes a unique and extensive protein export network in the infected RBC, dedicating at least 6% of its genome to the process. Understanding the full gamut of proteins involved in this process and the mechanisms by which P. falciparum alters the structure and function of RBCs is important both for a more complete understanding of the pathogenesis of malaria and for development of new therapeutic strategies to prevent or treat this devastating disease. This review focuses on what is currently known about exported parasite proteins, their interactions with the RBC and their likely pathophysiological consequences.
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10
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Remodeling of human red cells infected with Plasmodium falciparum and the impact of PHIST proteins. Blood Cells Mol Dis 2013; 51:195-202. [PMID: 23880461 DOI: 10.1016/j.bcmd.2013.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 06/08/2013] [Accepted: 06/10/2013] [Indexed: 01/27/2023]
Abstract
In an infected erythrocyte (iRBC), renovation and decoration are crucial for malarial parasite survival, pathogenesis and reproduction. Host cell remodeling is mediated by an array of diverse parasite-encoded export proteins that traffic within iRBC. These remodeling proteins extensively modify the membrane and cytoskeleton of iRBC and help in formation of parasite-induced novel organelles such as 'Maurer's Cleft (MC), tubulovesicular network (TVN) and parasitophorous vacuole membrane (PVM) inside the iRBC. The genome sequence of Plasmodium falciparum shows expansion of export proteins, which suggests a complex requirement of these export proteins for specific pathogenesis and erythrocyte remodeling. Plasmodium helical intersperse sub-telomeric (PHIST) is a family of seventy-two small export proteins and many of its recently discovered functional characteristics suggest an intriguing putative role in modification of an iRBC. This review highlights the recent advances in parasite genomics, proteomics, and cell biology studies unraveling the host cell modification; providing a speculation on the impact of PHIST proteins in modification of the iRBC.
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11
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Kitamura K, Kishi-Itakura C, Tsuboi T, Sato S, Kita K, Ohta N, Mizushima N. Autophagy-related Atg8 localizes to the apicoplast of the human malaria parasite Plasmodium falciparum. PLoS One 2012; 7:e42977. [PMID: 22900071 PMCID: PMC3416769 DOI: 10.1371/journal.pone.0042977] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 07/16/2012] [Indexed: 01/24/2023] Open
Abstract
Autophagy is a membrane-mediated degradation process, which is governed by sequential functions of Atg proteins. Although Atg proteins are highly conserved in eukaryotes, protozoa possess only a partial set of Atg proteins. Nonetheless, almost all protozoa have the complete factors belonging to the Atg8 conjugation system, namely, Atg3, Atg4, Atg7, and Atg8. Here, we report the biochemical properties and subcellular localization of the Atg8 protein of the human malaria parasite Plasmodium falciparum (PfAtg8). PfAtg8 is expressed during intra-erythrocytic development and associates with membranes likely as a lipid-conjugated form. Fluorescence microscopy and immunoelectron microscopy show that PfAtg8 localizes to the apicoplast, a four membrane-bound non-photosynthetic plastid. Autophagosome-like structures are not observed in the erythrocytic stages. These data suggest that, although Plasmodium parasites have lost most Atg proteins during evolution, they use the Atg8 conjugation system for the unique organelle, the apicoplast.
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Affiliation(s)
- Kei Kitamura
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Environmental Parasitology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Chieko Kishi-Itakura
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takafumi Tsuboi
- Cell-Free Science and Technology Research Center and Venture Business Laboratory, Ehime University, Matsuyama, Ehime, Japan
| | - Shigeharu Sato
- Division of Parasitology, MRC National Institute for Medical Research, London, United Kingdom
| | - Kiyoshi Kita
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nobuo Ohta
- Department of Environmental Parasitology, Tokyo Medical and Dental University, Tokyo, Japan
- * E-mail: (NO); (NM)
| | - Noboru Mizushima
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan
- * E-mail: (NO); (NM)
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12
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Lal K, Prieto JH, Bromley E, Sanderson SJ, Yates JR, Wastling JM, Tomley FM, Sinden RE. Characterisation of Plasmodium invasive organelles; an ookinete microneme proteome. Proteomics 2009; 9:1142-51. [PMID: 19206106 DOI: 10.1002/pmic.200800404] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Secretion of microneme proteins is essential to Plasmodium invasion but the molecular composition of these secretory organelles remains poorly defined. Here, we describe the first Plasmodium microneme proteome. Purification of micronemes by subcellular fractionation from cultured ookinetes was confirmed by enrichment of known micronemal proteins and electron microscopy. Quantitation of electron micrographs showed >14-fold microneme enrichment compared to the intact ookinete, such that micronemes comprised 85% of the identifiable organelles in the fraction. Gel LC-MS/MS of the most abundant protein constituents of the fraction identified three known micronemal proteins chitinase, CTRP, SOAP, together with protein disulphide isomerase (PDI) and HSP70. Highly sensitive MudPIT shotgun proteomics described a total of 345 proteins in the fraction. M1 aminopeptidase and PDI, the former a recognised target of drug development, were both shown to have a micronemal location by IFA. We further identified numerous proteins with established vesicle trafficking and signaling functions consistent with micronemes being part of a regulated secretory pathway. Previously uncharacterised proteins comprise the largest functional group of the microneme proteome and will include secreted proteins important to invasion.
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Affiliation(s)
- Kalpana Lal
- Division of Cell and Molecular Biology, Imperial College London, UK.
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13
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Maier AG, Cooke BM, Cowman AF, Tilley L. Malaria parasite proteins that remodel the host erythrocyte. Nat Rev Microbiol 2009; 7:341-54. [PMID: 19369950 DOI: 10.1038/nrmicro2110] [Citation(s) in RCA: 289] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exported proteins of the malaria parasite Plasmodium falciparum interact with proteins of the erythrocyte membrane and induce substantial changes in the morphology, physiology and function of the host cell. These changes underlie the pathology that is responsible for the deaths of 1-2 million children every year due to malaria infections. The advent of molecular transfection technology, including the ability to generate deletion mutants and to introduce fluorescent reporter proteins that track the locations and dynamics of parasite proteins, has increased our understanding of the processes and machinery for export of proteins in P. falciparum-infected erythrocytes and has provided us with insights into the functions of the parasite protein exportome. We review these developments, focusing on parasite proteins that interact with the erythrocyte membrane skeleton or that promote delivery of the major virulence protein, PfEMP1, to the erythrocyte membrane.
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Affiliation(s)
- Alexander G Maier
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria, Australia
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14
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Haldar K, Murphy SC, Milner DA, Taylor TE. Malaria: mechanisms of erythrocytic infection and pathological correlates of severe disease. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2008; 2:217-49. [PMID: 18039099 DOI: 10.1146/annurev.pathol.2.010506.091913] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Malaria is an ancient disease that continues to cause enormous human morbidity and mortality. The life cycle of the causative parasite involves multiple tissues in two distinct host organisms, mosquitoes and humans. However, all the clinical symptoms of malaria are a consequence of infection of human erythrocytes. An understanding of the basic mechanisms that govern parasite invasion, remodeling, growth, and reinvasion of erythrocytes and the complex events leading to tissue pathology may yield new diagnostics and treatments for malaria. This approach is revealing a more complete picture of the most serious syndrome associated with this infection-cerebral malaria. We focus on the most recent understanding of the molecular basis of infection, summarize our finding from an ongoing pediatric cerebral malaria autopsy study in Malawi, and integrate these insights to malarial pathology.
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Affiliation(s)
- Kasturi Haldar
- Department of Pathology and Microbiology-Immunology, Northwestern University, Chicago, Illinois 60611, USA.
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15
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Lamarque M, Tastet C, Poncet J, Demettre E, Jouin P, Vial H, Dubremetz JF. Food vacuole proteome of the malarial parasite Plasmodium falciparum. Proteomics Clin Appl 2008; 2:1361-74. [PMID: 21136929 DOI: 10.1002/prca.200700112] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Indexed: 11/08/2022]
Abstract
The Plasmodium falciparum food vacuole (FV) is a lysosome-like organelle where erythrocyte hemoglobin digestion occurs. It is a favorite target in the development of antimalarials. We have used a tandem mass spectrometry approach to investigate the proteome of an FV-enriched fraction and identified 116 proteins. The electron microscopy analysis and the Western blot data showed that the major component of the fraction was the FV and, as expected, the majority of previously known FV markers were recovered. Of particular interest, several proteins involved in vesicle-mediated trafficking were identified, which are likely to play a key role in FV biogenesis and/or FV protein trafficking. Recovery of parasite surface proteins lends support to the cytostomal pathway of hemoglobin ingestion as a FV trafficking route. We have identified 32 proteins described as hypothetical in the databases. This insight into FV protein content provides new clues towards understanding the biological function of this organelle in P. falciparum.
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Affiliation(s)
- Mauld Lamarque
- Dynamique Moléculaire des Interactions Membranaires CNRS UMR 5235, Université Montpellier II, Montpellier, France
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16
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Issar N, Roux E, Mattei D, Scherf A. Identification of a novel post-translational modification in Plasmodium falciparum: protein sumoylation in different cellular compartments. Cell Microbiol 2008; 10:1999-2011. [PMID: 18547337 PMCID: PMC2613257 DOI: 10.1111/j.1462-5822.2008.01183.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
SUMO (Small Ubiquitin-like MOdifier) conjugation is a post-translational modification implicated in a variety of cellular functions including transcriptional regulation, nuclear location and signal transduction. Sumoylation, although conserved and vital in eukaryotes, has not been studied in malaria parasites. Here, we identify SUMO conjugation of blood stage parasites of Plasmodium falciparum. Antibodies raised against synthetic peptides of the plasmodial SUMO orthologue PfSUMO, a 100-amino-acid protein, reacted with distinctive subcellular compartments of the parasitized erythrocyte during blood stage development. Anti-PfSUMO stains the nucleus and parasite cytoplasm. We also found antibody reactivity in the host cell cytoplasm with the parasite-derived structures called Maurer's clefts. Anti-PfSUMO reacts in Western blot with a number of blood stage proteins ranging from approximately 40–250 kDa. Parasites expressing FLAG-tagged PfSUMO gave similar results in Immunofluorescence assay and Western blots. In addition, we show that anti-PfSUMO identified PfSir2, a telomere-associated nuclear protein involved in var gene silencing, as a target for sumoylation. Furthermore, LC-MS/MS analysis of a two-step immunoprecipitation (IP) with anti-FLAG and anti-PfSUMO antibodies reveals a number of putative P. falciparum sumoylated proteins. Our results imply that SUMO conjugation has an essential function in a number of different biological processes in P. falciparum.
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Affiliation(s)
- Neha Issar
- Institut Pasteur- CNRS URA 2581, Biology of Host-Parasite Interactions Unit, F75724 Paris, France
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17
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Tilley L, Hanssen E. A 3D view of the host cell compartment in P. falciparum-infected erythrocytes. Transfus Clin Biol 2008; 15:72-81. [PMID: 18501653 DOI: 10.1016/j.tracli.2008.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 03/27/2008] [Indexed: 10/22/2022]
Abstract
The most deadly of the human malaria parasites, Plasmodium falciparum, invades the erythrocytes of its host and initiates a remarkable series of morphological rearrangements within the host cell cytoplasm. The mature erythrocyte is effectively a floating sack of haemoglobin with no endogenous protein synthesis or protein trafficking machinery. In order to colonise and remodel its extracellular space, the parasite generates a series of novel structures that are involved in the export of virulence factors to the surface of the host cell. These include extensions of the parasite's vacuolar membrane, known as the tubulovesicular network, and structures referred to as Maurer's clefts. Maurer's clefts are convoluted collections of distorted discs that are tethered to the red blood cell membrane by structures with stalk-like profiles. Recently electron tomography has enabled visualisation--in three dimensions and at unprecedented resolution--the complexity of the membrane systems within the infected RBC cytoplasm.
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Affiliation(s)
- L Tilley
- Department of Biochemistry and Centre of Excellence for Coherent X-ray Science, La Trobe University, Melbourne, Victoria 3086, Australia.
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18
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Vincensini L, Fall G, Berry L, Blisnick T, Braun Breton C. The RhopH complex is transferred to the host cell cytoplasm following red blood cell invasion by Plasmodium falciparum. Mol Biochem Parasitol 2008; 160:81-9. [PMID: 18508137 DOI: 10.1016/j.molbiopara.2008.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 04/03/2008] [Accepted: 04/04/2008] [Indexed: 11/29/2022]
Abstract
The high-molecular mass rhoptry protein complex (PfRhopH), which comprises three distinct gene products, RhopH1, RhopH2, and RhopH3, is known to be secreted and transferred to the parasitophorous vacuole membrane upon invasion of a red blood cell by the malaria parasite Plasmodium falciparum. Here we show that the merozoite-acquired RhopH complex is also transferred to defined domains of the red blood cell cytoplasm, and possibly transiently associated with Maurer's clefts. This is the first report of trafficking in the host cell cytoplasm for P. falciparum rhoptry proteins secreted upon red blood cell invasion. Based on its newly identified sub-cellular location and the phenotype of RhopH1 mutants, we propose that the RhopH complex participate in the assembly of the cytoadherence complex.
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Affiliation(s)
- Laetitia Vincensini
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 2581 Institut Pasteur, 25-28 Rue du Dr Roux, Paris, France
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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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Kats LM, Cooke BM, Coppel RL, Black CG. Protein Trafficking to Apical Organelles of Malaria Parasites - Building an Invasion Machine. Traffic 2007; 9:176-86. [PMID: 18047549 DOI: 10.1111/j.1600-0854.2007.00681.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lev M Kats
- NHMRC Program in Malaria, Department of Microbiology, Monash University, Victoria 3800, Australia
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21
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Adisa A, Frankland S, Rug M, Jackson K, Maier AG, Walsh P, Lithgow T, Klonis N, Gilson PR, Cowman AF, Tilley L. Re-assessing the locations of components of the classical vesicle-mediated trafficking machinery in transfected Plasmodium falciparum. Int J Parasitol 2007; 37:1127-41. [PMID: 17428488 DOI: 10.1016/j.ijpara.2007.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 02/15/2007] [Accepted: 02/16/2007] [Indexed: 11/16/2022]
Abstract
The malaria parasite, Plasmodium falciparum, exports proteins beyond the confines of its own plasma membrane, however there is debate regarding the machinery used for these trafficking events. We have generated transgenic parasites expressing chimeric proteins and used immunofluorescence studies to determine the locations of plasmodial homologues of the COPII component, Sar1p, and the Golgi-docking protein, Bet3p. The P. falciparum Sar1p (PfSar1p) chimeras bind to the endoplasmic reticulum surface and define a network of membranes wrapped around parasite nuclei. As the parasite matures, the endomembrane systems of individual merozoites remain interconnected until very late in schizogony. Antibodies raised against plasmodial Bet3p recognise two foci of reactivity in early parasite stages that increase in number as the parasite matures. Some of the P. falciparum Bet3p (PfBet3p) compartments are juxtaposed to compartments defined by the cis Golgi marker, PfGRASP, while others are distributed through the cytoplasm. The compartments defined by the trans Golgi marker, PfRab6, are separate, suggesting that the Golgi is dispersed. Bet3p-green fluorescent protein (GFP) is partly associated with punctate structures but a substantial population diffuses freely in the parasite cytoplasm. By contrast, yeast Bet3p is very tightly associated with immobile structures. This study challenges the view that the COPII complex and the Golgi apparatus are exported into the infected erythrocyte cytoplasm.
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Affiliation(s)
- Akinola Adisa
- Department of Biochemistry, La Trobe University, Melbourne 3086, Vic., Australia
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22
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Sokolova YY, Snigirevskaya ES, Komissarchik YY. The Golgi apparatus in parasitic protists. ACTA ACUST UNITED AC 2007. [DOI: 10.1134/s1990519x07040037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Tilley L, McFadden G, Cowman A, Klonis N. Illuminating Plasmodium falciparum-infected red blood cells. Trends Parasitol 2007; 23:268-77. [PMID: 17434344 DOI: 10.1016/j.pt.2007.04.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 03/21/2007] [Accepted: 04/04/2007] [Indexed: 11/20/2022]
Abstract
The malaria parasite undergoes a remarkable series of morphological transformations, which underpin its life in both human and mosquito hosts. The advent of molecular transfection technology coupled with the ability to introduce fluorescent reporter proteins that faithfully track and expose the activities of parasite proteins has revolutionized our view of parasite cell biology. The greatest insights have been realized in the erythrocyte stages of Plasmodium falciparum. P. falciparum invades and remodels the human erythrocyte: it feeds on haemoglobin, grows and divides, and subverts the physiology of its hapless host. Fluorescent proteins have been employed to track and dissect each of these processes and have revealed details and exposed new paradigms.
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Affiliation(s)
- Leann Tilley
- Department of Biochemistry, La Trobe University, Melbourne, Victoria 3086, Australia.
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Abstract
PURPOSE OF REVIEW Plasmodium falciparum causes the most virulent form of human malarias. It is a protozoan parasite that infects human erythrocytes and the erythrocytic stages are responsible for all symptoms and pathologies of the disease. Critical to infection is the formation of a parasitophorous vacuolar membrane at the time of entry and within which the intracellular parasite proliferates. Since erythrocytes lack endocytic machinery, it is surprising that they can be infected by pathogens. This review summarizes recent studies of the erythrocyte-malaria interaction that have provided insights into properties of erythrocyte membranes as well as parasite mechanisms that remodel the erythrocyte. RECENT FINDINGS Themes revealed by recent literature suggest that both parasite and erythrocyte components regulate parasite entry and intracellular growth by extensively remodeling host membranes. These remodeling events include the invagination of the host cell membrane during parasite entry that results in the creation and maintenance of a vacuole that surrounds the intracellular organism, and the development of antigenic, structural and transport alterations during intracellular parasite development. SUMMARY The implications are that malarial erythrocyte remodeling events occur at a significant cost to the human host since many of the associated virulence events have been linked to severe disease pathologies.
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Affiliation(s)
- Kasturi Haldar
- Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
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25
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Pachebat JA, Kadekoppala M, Grainger M, Dluzewski AR, Gunaratne RS, Scott-Finnigan TJ, Ogun SA, Ling IT, Bannister LH, Taylor HM, Mitchell GH, Holder AA. Extensive proteolytic processing of the malaria parasite merozoite surface protein 7 during biosynthesis and parasite release from erythrocytes. Mol Biochem Parasitol 2006; 151:59-69. [PMID: 17097159 DOI: 10.1016/j.molbiopara.2006.10.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 09/15/2006] [Accepted: 10/11/2006] [Indexed: 11/21/2022]
Abstract
In Plasmodium falciparum, merozoite surface protein 7 (MSP7) was originally identified as a 22kDa protein on the merozoite surface and associated with the MSP1 complex shed during erythrocyte invasion. MSP7 is synthesised in schizonts as a 351-amino acid precursor that undergoes proteolytic processing. During biosynthesis the MSP1 and MSP7 precursors form a complex that is targeted to the surface of developing merozoites. In the sequential proteolytic processing of MSP7, N- and C-terminal 20 and 33kDa products of primary processing, MSP7(20) and MSP7(33) are formed and MSP7(33) remains bound to full length MSP1. Later in the mature schizont, MSP7(20) disappears from the merozoite surface and on merozoite release MSP7(33) undergoes a secondary cleavage yielding the 22kDa MSP7(22) associated with MSP1. In free merozoites, both MSP7(22) and a further cleaved product, MSP7(19) present only in some parasite lines, were detected; these two derivatives are shed as part of the protein complex with MSP1 fragments during erythrocyte invasion. Primary processing of MSP7 is brefeldin A-sensitive while secondary processing is resistant to both calcium chelators and serine protease inhibitors. Primary processing of MSP7 occurs prior to that of MSP1 in a post-Golgi compartment, whereas the secondary cleavage occurs on the surface of the developing merozoite, possibly at the time of MSP1 primary processing and well before the secondary processing of MSP1.
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Affiliation(s)
- Justin A Pachebat
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London NW1 1AA, UK
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Khattab A, Klinkert MQ. Maurer’s Clefts-Restricted Localization, Orientation and Export of a Plasmodium falciparum RIFIN. Traffic 2006; 7:1654-65. [PMID: 17014697 DOI: 10.1111/j.1600-0854.2006.00494.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RIFINs are clonally variant antigens expressed in Plasmodium falciparum. Transfection and the green fluorescence protein (GFP) tagged either internally or C-terminally to the 3D7 PFI0050c RIFIN gene product were used to investigate protein localization, orientation and trafficking. Green fluorescence pattern emerging from live transfectant parasites expressing each of the RIFIN-GFP chimera was different. The internally GFP-tagged protein was exported to Maurer's clefts (MC) in the erythrocyte cytosol, whereas the C-terminally GFP-tagged full-length RIFIN chimera was not trafficked out of the parasite. Interestingly, when some RIFIN-specific C-terminal amino acid sequences were removed, the resulting truncated molecule reached the MC. Using anti-RIFIN and anti-GFP antibodies to probe both live and fixed transfectants, staining was confined to MC and was not detected on the erythrocyte surface, a location previously suggested for this protein family. From selective permeabilization experiments, the highly variable portion of the RIFIN-GFP-insertion chimera appeared to be exposed to the erythrocyte cytosol, presumably anchored in the MC membrane via the two transmembrane domains. Trafficking of both chimeras in young ring stages was sensitive to Brefeldin A (BFA), although older rings showed differential sensitivity to BFA.
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Affiliation(s)
- Ayman Khattab
- Department of Molecular Medicine, Bernhard-Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, Hamburg 20359, Germany.
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Spycher C, Rug M, Klonis N, Ferguson DJP, Cowman AF, Beck HP, Tilley L. Genesis of and trafficking to the Maurer's clefts of Plasmodium falciparum-infected erythrocytes. Mol Cell Biol 2006; 26:4074-85. [PMID: 16705161 PMCID: PMC1489082 DOI: 10.1128/mcb.00095-06] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 02/15/2006] [Accepted: 03/04/2006] [Indexed: 11/20/2022] Open
Abstract
Malaria parasites export proteins beyond their own plasma membrane to locations in the red blood cells in which they reside. Maurer's clefts are parasite-derived structures within the host cell cytoplasm that are thought to function as a sorting compartment between the parasite and the erythrocyte membrane. However, the genesis of this compartment and the signals directing proteins to the Maurer's clefts are not known. We have generated Plasmodium falciparum-infected erythrocytes expressing green fluorescent protein (GFP) chimeras of a Maurer's cleft resident protein, the membrane-associated histidine-rich protein 1 (MAHRP1). Chimeras of full-length MAHRP1 or fragments containing part of the N-terminal domain and the transmembrane domain are successfully delivered to Maurer's clefts. Other fragments remain trapped within the parasite. Fluorescence photobleaching and time-lapse imaging techniques indicate that MAHRP1-GFP is initially trafficked to isolated subdomains in the parasitophorous vacuole membrane that appear to represent nascent Maurer's clefts. The data suggest that the Maurer's clefts bud from the parasitophorous vacuole membrane and diffuse within the erythrocyte cytoplasm before taking up residence at the cell periphery.
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Affiliation(s)
- Cornelia Spycher
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, Socinstrasse 57, CH 4002 Basel, Switzerland
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Blisnick T, Vincensini L, Fall G, Braun-Breton C. Protein phosphatase 1, a Plasmodium falciparum essential enzyme, is exported to the host cell and implicated in the release of infectious merozoites. Cell Microbiol 2006; 8:591-601. [PMID: 16548885 DOI: 10.1111/j.1462-5822.2005.00650.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The malarial parasite Plasmodium falciparum transposes a Golgi-like compartment, referred to as Maurer's clefts, into the cytoplasm of its host cell, the erythrocyte, and delivering parasite molecules to the host cell surface. We report here a novel role of the Maurer's clefts implicating a parasite protein phosphatase 1 (PP1) and related to the phosphorylation status of P. falciparum skeleton-binding protein 1 (PfSBP1), a trans-membrane protein of the clefts interacting with the host cell membrane via its carboxy-terminal domain. Based on co-immunoprecipitation and inhibition studies, we show that the parasite PP1 type phosphatase modulates the phosphorylation status of the amino-terminal domain of PfSBP1 in the lumen of Maurer's clefts. Importantly, the addition of a PP1 inhibitor, calyculin A, to late schizonts results in the hyperphosphorylation of PfSBP1 and prevents parasite release from the host cell. We propose that the hyperphosphorylation of PfSBP1 interferes with the release of merozoites, the invasive blood stage of the parasite, by increasing the red cell membrane stability. Moreover, the parasite PP1 phosphatase is the first enzyme essential for the parasite development detected in the Maurer's clefts.
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Affiliation(s)
- Thierry Blisnick
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 2581, France
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29
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Mercier C, Adjogble KDZ, Däubener W, Delauw MFC. Dense granules: are they key organelles to help understand the parasitophorous vacuole of all apicomplexa parasites? Int J Parasitol 2006; 35:829-49. [PMID: 15978597 DOI: 10.1016/j.ijpara.2005.03.011] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 03/07/2005] [Accepted: 03/18/2005] [Indexed: 02/06/2023]
Abstract
Together with micronemes and rhoptries, dense granules are specialised secretory organelles of Apicomplexa parasites. Among Apicomplexa, Plasmodium represents a model of parasites propagated by way of an insect vector, whereas Toxoplasma is a model of food borne protozoa forming cysts. Through comparison of both models, this review summarises data accumulated over recent years on alternative strategies chosen by these parasites to develop within a parasitophorous vacuole and explores the role of dense granules in this process. One of the characteristics of the Plasmodium erythrocyte stages is to export numerous parasite proteins into both the host cell cytoplasm and/or plasma membrane via the vacuole used as a step trafficking compartment. Whether this feature can be correlated to few storage granules and a restricted number of dense granule proteins, is not yet clear. By contrast, the Toxoplasma developing vacuole is decorated by abundantly expressed dense granule proteins and is characterised by a network of membranous nanotubes. Although the exact function of most of these proteins remains currently unknown, recent data suggest that some of these dense granule proteins could be involved in building the intravacuolar membranous network. Conserved expression of the Toxoplasma dense granule proteins throughout most of the parasite stages suggests that they could also be key elements of the cyst formation.
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Affiliation(s)
- Corinne Mercier
- Institut Jean Roget, Université Joseph Fourier, CNRS UMR 5163, Place du Commandant Nal., 38700 La Tronche, France.
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Abstract
To survive within erythrocytes, Plasmodium parasites have to put into place different membrane and sub-cellular compartments in order to import different nutrients and to export proteins/antigens. Infected cells pose not only a major world health risk by killing two million people per year, but also a very interesting cell biology problem, as within the erythrocyte the parasite resides inside a vacuole called the parasitophorous vacuole and as a consequence, it is separated from the blood stream by three membrane barriers, its own plasma membrane, the parasitophorous vacuole membrane and the erythrocyte plasma membrane. In spite of these three barriers the parasite is capable of secreting antigens and importing nutrients, and to do this, it has developed a complex vesicular system that extends into the red blood cell cytoplasm to the plasma membrane. Understanding how the parasite controls this extensive vesicular traffic has driven research into Plasmodium Rabs, whose potential role is discussed.
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Affiliation(s)
- Françoise Baunaure
- Laboratoire de biologie comparative des apicomplexes, UMR 8104 CNRS-Inserm U.567, Département maladies infectieuses, Hôpital Cochin, Bâtiment Gustave Roussy, Institut Cochin, 27, rue du Faubourg-Saint-Jacques, 75014 Paris, France
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31
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Lanzer M, Wickert H, Krohne G, Vincensini L, Braun Breton C. Maurer's clefts: A novel multi-functional organelle in the cytoplasm of Plasmodium falciparum-infected erythrocytes. Int J Parasitol 2006; 36:23-36. [PMID: 16337634 DOI: 10.1016/j.ijpara.2005.10.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 09/23/2005] [Accepted: 10/04/2005] [Indexed: 10/25/2022]
Abstract
Discovered in 1902 by Georg Maurer as a peculiar dotted staining pattern observable by light microscopy in the cytoplasm of erythrocytes infected with the human malarial parasite Plasmodium falciparum, the function of Maurer's clefts have remained obscure for more than a century. The growing interest in protein sorting and trafficking processes in malarial parasites has recently aroused the Maurer's clefts from their deep slumber. Mounting evidence suggests that Maurer's clefts are a secretory organelle, which the parasite establishes within its host erythrocyte, but outside its own confines, to route parasite proteins across the host cell cytoplasm to the erythrocyte surface where they play a role in nutrient uptake and immune evasion processes. Moreover, Maurer's clefts seem to play a role in cell signaling, merozoite egress, phospholipid biosynthesis and, possibly, other biochemical pathways. Here, we review our current knowledge of the ultrastructure of Maurer's clefts, their proteinaceous composition and their function in protein trafficking.
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Affiliation(s)
- Michael Lanzer
- Abteilung Parasitologie, Hygiene-Institut, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany.
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Knuepfer E, Rug M, Klonis N, Tilley L, Cowman AF. Trafficking determinants for PfEMP3 export and assembly under thePlasmodium falciparum-infected red blood cell membrane. Mol Microbiol 2005; 58:1039-53. [PMID: 16262789 DOI: 10.1111/j.1365-2958.2005.04895.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During the maturation of intracellular asexual stages of Plasmodium falciparum parasite-encoded proteins are exported into the erythrocyte cytosol. A number of these parasite proteins attach to the host cell cytoskeleton and facilitate transformation of a disk-shaped erythrocyte into a rounded and more rigid infected erythrocyte able to cytoadhere to the vasculature. Knob formation on the surface of infected erythrocytes is critical for this cytoadherence to the host endothelium. P. falciparum proteins have been identified that localize to the parasite-infected erythrocyte membrane: the variant cytoadherence ligand erythrocyte membrane protein 1 (PfEMP1), the knob-associated histidine-rich protein (KAHRP) and the erythrocyte membrane protein 3 (PfEMP3). In this study, we have generated parasites expressing PfEMP3-green fluorescent protein chimeras and identified domains involved in entry to the secretory pathway, export across the parasitophorous vacuolar membrane and attachment to Maurer's clefts and the erythrocyte membrane. Solubility assays, fluorescence photobleaching experiments and immunogold electron microscopy suggest that the exported chimeric proteins are trafficked in a complex rather than in vesicles. This study characterizes elements involved in the tight but transient binding of PfEMP3 to Maurer's clefts and shows that the same elements are necessary for correct assembly under the erythrocyte membrane.
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Affiliation(s)
- Ellen Knuepfer
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Vic. 3050, Australia
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33
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Möskes C, Burghaus PA, Wernli B, Sauder U, Dürrenberger M, Kappes B. Export of Plasmodium falciparum calcium-dependent protein kinase 1 to the parasitophorous vacuole is dependent on three N-terminal membrane anchor motifs. Mol Microbiol 2005; 54:676-91. [PMID: 15491359 DOI: 10.1111/j.1365-2958.2004.04313.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calcium-dependent protein kinases play a pivotal role in calcium signalling in plants and some protozoa, including the malaria parasites. They are found in various subcellular locations, suggesting an involvement in multiple signal transduction pathways. Recently, Plasmodium falciparum calcium-dependent protein kinase 1 (PfCDPK1) has been found in the membrane and organelle fraction of the parasite. The kinase contains three motifs for membrane binding at its N-terminus, a consensus sequence for myristoylation, a putative palmitoylation site and a basic motif. Endogenous PfCDPK1 and the in vitro translated kinase were both shown to be myristoylated. The supposed membrane attachment function of the basic cluster was experimentally verified and shown to participate together with N-myristoylation in membrane anchoring of the kinase. Using immunogold electron microscopy, the protein was detected in the parasitophorous vacuole and the tubovesicular system of the parasite. Mutagenesis of the predicted acylated residues and the basic motif confirmed that dual acylation and the basic cluster are required for correct targeting of Aequorea victoria green fluorescent protein to the parasitophorous vacuole, suggesting that PfCDPK1 as the leishmanial hydrophilic acylated surface protein B is a representative of a novel class of proteins whose export is dependent on a 'non-classical' pathway involving N-myristoylation/palmitoylation.
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Affiliation(s)
- Christian Möskes
- Parasitology Department, Institute for Hygiene, Heidelberg University, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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Coppens I, Vielemeyer O. Insights into unique physiological features of neutral lipids in Apicomplexa: from storage to potential mediation in parasite metabolic activities. Int J Parasitol 2005; 35:597-615. [PMID: 15862574 DOI: 10.1016/j.ijpara.2005.01.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 01/05/2005] [Accepted: 01/13/2005] [Indexed: 01/18/2023]
Abstract
The fast intracellular multiplication of apicomplexan parasites including Toxoplasma and Plasmodium, requires large amounts of lipids necessary for the membrane biogenesis of new progenies. Hence, the study of lipids is fundamental in order to understand the biology and pathogenesis of these deadly organisms. Much has been reported on the importance of polar lipids, e.g. phospholipids in Plasmodium. Comparatively, little attention has been paid to the metabolism of neutral lipids, including sterols, steryl esters and acylglycerols. In eukaryotic cells, free sterols are membrane components whereas steryl esters and acylglycerols are stored in cytosolic lipid inclusions. The first part of this review describes the recent advances in neutral lipid synthesis and storage in Toxoplasma and Plasmodium. New potential pharmacological targets in the pathways producing neutral lipids are outlined. In addition to lipid bodies, Apicomplexa contain unique secretory organelles involved in parasite invasion named rhoptries. These compartments appear to sequester most of the cholesterol found in the exocytic pathway. The second part of the review focuses on rhoptry cholesterol and its potential roles in the biogenesis, structural organisation and function of these unique organelles among eukaryotes.
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Affiliation(s)
- Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205-2223, USA.
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35
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Blisnick T, Vincensini L, Barale JC, Namane A, Braun Breton C. LANCL1, an erythrocyte protein recruited to the Maurer's clefts during Plasmodium falciparum development. Mol Biochem Parasitol 2005; 141:39-47. [PMID: 15811525 DOI: 10.1016/j.molbiopara.2005.01.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Revised: 11/11/2004] [Accepted: 01/18/2005] [Indexed: 11/25/2022]
Abstract
As the malarial parasite Plasmodium falciparum develops inside the erythrocyte, parasite-derived membrane structures, referred to as Maurer's clefts, play an important role in parasite development by delivering parasite proteins to the host cell surface, and participating in the assembly of the cytoadherence complex, essential for the pathogenesis of cerebral malaria. PfSBP1 is an integral membrane protein of the clefts, interacting with an erythrocyte cytosolic protein, identified here as the human Lantibiotic synthetase component C-like protein LANCL1. LANCL1 is specifically recruited to the surface of Maurer's clefts in P. falciparum mature blood stages. We propose that the interaction between PfSBP1 and LANCL1 is central for late steps of the parasite development to prevent premature rupture of the red blood cell membrane.
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Affiliation(s)
- Thierry Blisnick
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 2581, France
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36
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Vincensini L, Richert S, Blisnick T, Van Dorsselaer A, Leize-Wagner E, Rabilloud T, Braun Breton C. Proteomic analysis identifies novel proteins of the Maurer's clefts, a secretory compartment delivering Plasmodium falciparum proteins to the surface of its host cell. Mol Cell Proteomics 2005; 4:582-93. [PMID: 15671043 DOI: 10.1074/mcp.m400176-mcp200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel method was validated for the efficient distinction between malaria parasite-derived and host cell proteins in mass spectrometry analyses. This method was applied to a ghost fraction from Plasmodium falciparum-infected erythrocytes containing the red blood cell plasma membrane, the erythrocyte submembrane skeleton, and the Maurer's clefts, a Golgi-like apparatus linked to and addressing parasite proteins to the host cell surface. This method allowed the identification of 78 parasite proteins. Among these we identified seven novel proteins of the Maurer's clefts based on immunofluorescence studies and proteinase K digestion assays. The products of six contiguous genes located on chromosome 5 were identified, and the location within the Maurer's clefts was established for two of them. This suggests a clustering of genes encoding Maurer's cleft proteins. Our study sheds new light on the biological function of the Maurer's clefts, which are central to the pathogenesis and to the intraerythrocytic development of P. falciparum.
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Affiliation(s)
- Laetitia Vincensini
- Unité de Biologie des Interactions Hôte-Parasite, CNRS URA 2581, Institut Pasteur, 25-28 Rue du Dr Roux, 75724 Paris Cedex 15, France
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37
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DeRocher A, Gilbert B, Feagin JE, Parsons M. Dissection of brefeldin A-sensitive and -insensitive steps in apicoplast protein targeting. J Cell Sci 2005; 118:565-74. [PMID: 15657083 DOI: 10.1242/jcs.01627] [Citation(s) in RCA: 57] [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] Open
Abstract
The apicoplast is a relict plastid found in many apicomplexans, including the pathogens Toxoplasma gondii and Plasmodium falciparum. Nucleus-encoded apicoplast proteins enter the ER, and after cleavage of the signal sequence, are routed to the apicoplast by virtue of a transit peptide, which is subsequently removed. To assess the mechanisms of localization we examined stable transfectants of T. gondii for the localization and processing of various GFP fusion proteins. GFP fusions bearing apicoplast targeting sequences targeted efficiently to the plastid, with no retention in the ER, even when an ER retention/retrieval sequence was added. Incubation with brefeldin A, which blocks ER-to-Golgi trafficking by inhibiting a GTP exchange factor required for retrograde trafficking, blocked the processing of the protein. Surprisingly, it did not affect the immunofluorescence pattern. To avoid the potentially misleading presence of pre-existing GFP fusion protein in the apicoplast, we used a ligand-regulated aggregation system to arrest the GFP fusion protein in the ER prior to trafficking. Upon addition of ligand to promote disaggregation, the fusion protein targeted to the plastid, even in the presence of brefeldin A. Ligand release at 15 degrees C, which blocks trafficking of Golgi-routed proteins, also allowed significant localization to the plastid. Our data indicate that apicoplast proteins can localize to the region of the plastid when Golgi trafficking is inhibited, but suggest that some steps in import or maturation of the proteins may require a brefeldin A-sensitive GTP exchange factor.
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Affiliation(s)
- Amy DeRocher
- Seattle Biomedical Research Institute, 307 Westlake Avenue N., Suite 500 Seattle, WA 98109, USA
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38
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Papakrivos J, Newbold CI, Lingelbach K. A potential novel mechanism for the insertion of a membrane protein revealed by a biochemical analysis of the Plasmodium falciparum cytoadherence molecule PfEMP-1. Mol Microbiol 2004; 55:1272-84. [PMID: 15686570 DOI: 10.1111/j.1365-2958.2004.04468.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is exposed on the surface of infected erythrocytes where it both acts as an important pathogenicity factor in malaria and undergoes antigenic variation as a means of immune evasion. Because the mammalian erythrocyte lacks a protein secretory machinery there has been much interest in elucidating the mechanism whereby this protein is transferred from its site of synthesis within the parasite to its final destination. Current opinion favours a mechanism whereby PfEMP-1 becomes cotranslationally inserted into the endoplasmic reticulum of the parasite and is subsequently transported as an integral part of an erythrocyte cytoplasmic membrane system derived from the parasite. Here we show that the solubility characteristics of this protein during several stages of its transport pathway are inconsistent with this view. Instead we propose that the protein is synthesized as a peripheral membrane protein which only when it arrives at its final destination assumes a transmembrane topology. Even in this state, the extractability of the protein with urea suggest that it is anchored in the membrane by protein-protein rather than by protein-lipid interaction.
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39
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Palacpac NMQ, Hiramine Y, Mi-ichi F, Torii M, Kita K, Hiramatsu R, Horii T, Mitamura T. Developmental-stage-specific triacylglycerol biosynthesis, degradation and trafficking as lipid bodies in Plasmodium falciparum-infected erythrocytes. J Cell Sci 2004; 117:1469-80. [PMID: 15020675 DOI: 10.1242/jcs.00988] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Triacylglycerol (TAG) serves as a major energy storage molecule in eukaryotes. In Plasmodium, however, this established function of TAG appears unlikely, despite detecting previously considerable amount of TAG associated with intraerythrocytic parasites, because plasmodial cells have very little capacity to oxidize fatty acids. Thus, it is plausible that TAG and its biosynthesis in Plasmodium have other functions. As a first step in understanding the biological significance of TAG and its biosynthesis to the intraerythrocytic proliferation of Plasmodium falciparum, we performed detailed characterization of TAG metabolism and trafficking in parasitized erythrocyte. Metabolic labeling using radiolabeled-oleic and palmitic acids in association with serum albumin, which have been shown to be among the serum essential factors for intraerythrocytic proliferation of P. falciparum, revealed that accumulation of TAG was strikingly pronounced from trophozoite to schizont, whereas TAG degradation became active from schizont to segmented schizont; the consequent products, free fatty acids, were released into the medium during schizont rupture and/or merozoite release. These results were further supported by visualization of lipid bodies through immunofluorescence and electron microscopy. At the schizont stages, there is some evidence that the lipid bodies are partly localized in the parasitophorous vacuole. Interestingly, the discrete formation and/or trafficking of lipid bodies are inhibited by brefeldin A and trifluoperazine. Inhibition by trifluoperazine hints at least that a de novo TAG biosynthetic pathway via phosphatidic acid contributes to lipid body formation. Indeed, biochemical analysis reveals a higher activity of acyl-CoA:diacylglycerol acyltransferase, the principal enzyme in the sn-glycerol-3-phosphate pathway for TAG synthesis, at trophozoite and schizont stages. Together, these results establish that TAG metabolism and trafficking in P. falciparum-infected erythrocyte occurs in a stage-specific manner during the intraerythrocytic cycle and we propose that these unique and dynamic cellular events participate during schizont rupture and/or merozoite release.
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Cooke BM, Lingelbach K, Bannister LH, Tilley L. Protein trafficking in Plasmodium falciparum-infected red blood cells. Trends Parasitol 2004; 20:581-9. [PMID: 15522668 DOI: 10.1016/j.pt.2004.09.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Plasmodium falciparum inhabits a niche within the most highly terminally differentiated cell in the human body--the mature red blood cell. Life inside this normally quiescent cell offers the parasite protection from the host's immune system, but provides little in the way of cellular infrastructure. To survive and replicate in the red blood cell, the parasite exports proteins that interact with and dramatically modify the properties of the host red blood cell. As part of this process, the parasite appears to establish a system within the red blood cell cytosol that allows the correct trafficking of parasite proteins to their final cellular destinations. In this review, we examine recent developments in our understanding of the pathways and components involved in the delivery of important parasite-encoded proteins to their final destination in the host red blood cell. These complex processes are not only fundamental to the survival of malaria parasites in vivo, but are also major determinants of the unique pathogenicity of this parasite.
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Affiliation(s)
- Brian M Cooke
- Department of Microbiology, Monash University, Victoria 3800, Australia.
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41
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Przyborski JM, Lanzer M. Protein transport and trafficking inPlasmodium falciparum-infected erythrocytes. Parasitology 2004; 130:373-88. [PMID: 15830811 DOI: 10.1017/s0031182004006729] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The human malarial parasitePlasmodium falciparumextensively modifies its host erythrocyte, and to this end, is faced with an interesting challenge. It must not only sort proteins to common organelles such as endoplasmic reticulum, Golgi and mitochondria, but also target proteins across the ‘extracellular’ cytosol of its host cell. Furthermore, as a member of the phylum Apicomplexa, the parasite has to sort proteins to novel organelles such as the apicoplast, micronemes and rhoptries. In order to overcome these difficulties, the parasite has created a novel secretory system, which has been characterized in ever-increasing detail in the past decade. Along with the ‘hardware’ for a secretory system, the parasite also needs to ‘program’ proteins to enable high fidelity sorting to their correct subcellular location. The nature of these sorting signals has remained until relatively recently, enigmatic. Experimental work has now begun to dissect the sorting signals responsible for correct subcellular targeting of parasite-encoded proteins. In this review we summarize the current understanding of such signals, and comment on their role in protein sorting in this organism, which may become a model for the study of novel protein trafficking mechanisms.
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Affiliation(s)
- J M Przyborski
- Hygiene Institute, Department of Parasitology, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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42
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Tonkin CJ, van Dooren GG, Spurck TP, Struck NS, Good RT, Handman E, Cowman AF, McFadden GI. Localization of organellar proteins in Plasmodium falciparum using a novel set of transfection vectors and a new immunofluorescence fixation method. Mol Biochem Parasitol 2004; 137:13-21. [PMID: 15279947 DOI: 10.1016/j.molbiopara.2004.05.009] [Citation(s) in RCA: 367] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Accepted: 05/04/2004] [Indexed: 11/23/2022]
Abstract
The apicoplast and mitochondrion of the malaria parasite Plasmodium falciparum are important intracellular organelles and targets of several anti-malarial drugs. In recent years, our group and others have begun to piece together the metabolic pathways of these organelles, with a view to understanding their functions and identifying further anti-malarial targets. This has involved localization of putative organellar proteins using fluorescent reporter proteins such as green fluorescent protein (GFP). A major limitation to such an approach is the difficulties associated with using existing plasmids to genetically modify P. falciparum. In this paper, we present a novel series of P. falciparum transfection vectors based around the Gateway recombinatorial cloning system. Our system makes it considerably easier to construct fluorescent reporter fusion proteins, as well as allowing the use of two selectable markers. Using this approach, we localize proteins involved in isoprenoid biosynthesis and the posttranslational processing of apicoplast-encoded proteins to the apicoplast, and a protein putatively involved in the citric acid cycle to the mitochondrion. To confirm the localization of these proteins, we have developed a new immunofluorescence assay (IFA) protocol using antibodies specific to the apicoplast and mitochondrion. In comparison with published IFA methods, we find that ours maintains considerably better structural preservation, while still allowing sufficient antibody binding as well as preserving reporter protein fluorescence. In summary, we present two important new tools that have enabled us to characterize some of the functions of the apicoplast and mitochondrion, and which will be of use to the wider malaria research community in elucidating the localization of other P. falciparum proteins.
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Affiliation(s)
- Christopher J Tonkin
- Plant Cell Biology Research Centre, School of Botany, The University of Melbourne, Parkville, Vic. 3010, Australia
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43
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Li H, Han Z, Lu Y, Lin Y, Zhang L, Wu Y, Wang H. Isolation and functional characterization of a dynamin-like gene from Plasmodium falciparum. Biochem Biophys Res Commun 2004; 320:664-71. [PMID: 15240099 DOI: 10.1016/j.bbrc.2004.06.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Indexed: 11/18/2022]
Abstract
A novel dynamin-like GTPase gene, Pfdyn1, was cloned from an asexual stage cDNA library of Plasmodium falciparum Dd2 strain. Pfdyn1 contains a highly conserved N-terminal tripartite GTPase domain, a coiled-coil region, and a C-terminal 129 aa unknown function domain. Like yeast Vps1p, it lacks pleckstrin homology domain and proline-rich region. Western blot analysis showed that Pfdyn1 is a Triton X-100 insoluble protein expressed only in the mature sub-stage. Morphological studies indicated that Pfdyn1 is partly co-localized with PfGRP, a known ER-resident protein, and localizes diffusely with several membrane structures and a 60-100 nm vesicle both inside and on surface of the parasites and also in the cytoplasm of infected erythrocytes. The dsRNA originated by C-terminus fragment of Pfdyn1 inhibits markedly the growth of P. falciparum parasite at the erythrocyte stage. Those data showed that Pfdyn1 is a conservative, membrane related protein and plays an essential role for the survival of Plasmodium parasite.
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Affiliation(s)
- Huiliang Li
- Department of Etiology, Molecular Parasitology Laboratory, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
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44
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Moriyama Y, Hayashi M, Yatsushiro S, Yamamoto A. Vacuolar proton pumps in malaria parasite cells. J Bioenerg Biomembr 2004; 35:367-75. [PMID: 14635782 DOI: 10.1023/a:1025785000544] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The malaria parasite is a unicellular protozoan parasite of the genus Plasmodium that causes one of the most serious infectious diseases for human beings. Like other protozoa, the malaria parasite possesses acidic organelles, which may play an essential role(s) in energy acquisition, resistance to antimalarial agents, and vesicular trafficking. Recent evidence has indicated that two types of vacuolar proton pumps, vacuolar H+-ATPase and vacuolar H+-pyrophosphatase, are responsible for their acidification. In this mini-review, we discuss the recent progress on vacuolar proton pumps in the malaria parasite.
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Affiliation(s)
- Yoshinori Moriyama
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
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45
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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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46
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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: 140] [Impact Index Per Article: 6.7] [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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47
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Abstract
During intra-erythrocytic development, the human malarial parasite Plasmodium falciparum extensively remodels its adopted cellular home by exporting proteins beyond the confines of its own plasma membrane, but is, however, faced with a major problem: the lack of an endogenous protein trafficking machinery within the host erythrocyte. Thus, in order to export proteins the parasite has to install its own protein export system within the host erythrocyte. A growing body of evidence suggests that Maurer's clefts, parasite-derived membranous structures in the cytosol of the host cell, are a crucial component of this protein sorting and trafficking machinery. In this review we summarize our current understanding of the ultra-structure of Maurer's clefts and their role in protein transport process.
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Affiliation(s)
- Jude M Przyborski
- Department of Parasitology, Hygiene Institute, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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48
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Taraschi TF, O'Donnell M, Martinez S, Schneider T, Trelka D, Fowler VM, Tilley L, Moriyama Y. Generation of an erythrocyte vesicle transport system by Plasmodium falciparum malaria parasites. Blood 2003; 102:3420-6. [PMID: 12869498 DOI: 10.1182/blood-2003-05-1448] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The asexual maturation of Plasmodium falciparum is accompanied by the transport of parasite-encoded proteins to the erythrocyte plasma membrane. Activation of G proteins by treatment with aluminum fluoride produced an accumulation within the erythrocyte cytosol of vesicles coated with Plasmodium homologues of COPII and N-ethylmaleimide-sensitive factor, proteins involved in intracellular transport between the Golgi apparatus and the endoplasmic reticulum. These vesicles contain malarial proteins that appear on the erythrocyte plasma membrane, as well as actin and myosin. It is proposed that the parasite adapted a process well established for intracellular transport to mediate the extracellular movement of its proteins through the erythrocyte cytosol to the surface membrane.
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Affiliation(s)
- Theodore F Taraschi
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA 19107, USA.
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49
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Lopez-Estraño C, Bhattacharjee S, Harrison T, Haldar K. Cooperative domains define a unique host cell-targeting signal in Plasmodium falciparum-infected erythrocytes. Proc Natl Acad Sci U S A 2003; 100:12402-7. [PMID: 14514891 PMCID: PMC218770 DOI: 10.1073/pnas.2133080100] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2003] [Accepted: 08/19/2003] [Indexed: 11/18/2022] Open
Abstract
When the malaria parasite Plasmodium falciparum infects an erythrocyte, it resides in a parasitophorous vacuole and remarkably exports proteins into the periphery of its host cell. Two of these proteins, the histidine-rich proteins I and II (PfHRPI and PfHRPII), are exported to the erythrocyte cytoplasm. PfHRPI has been linked to cell-surface "knobby" protrusions that mediate cerebral malaria and are a frequent cause of death. PfHRPII has been implicated in (i) the production of hemozoin, the black pigment associated with disease, as well as (ii) interactions with the erythrocyte cytoskeleton. Here we show that a tripartite signal that is comprised of an endoplasmic reticulum-type signal sequence followed by a bipartite vacuolar translocation signal derived from HRPII and HRPI exports GFP from the parasitophorous vacuole to the host cytoplasm. The bipartite vacuolar translocation signal is comprised of unique, peptidic (approximately equal to 40-aa) sequences. A domain within it contains the signal for export to "cleft" transport intermediates in the host erythrocyte and may thereby regulate the pathway of export to the host cytoplasm. A signal for posttranslational, vacuolar exit of proteins has hitherto not been described in eukaryotic secretion.
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Affiliation(s)
- Carlos Lopez-Estraño
- Departments of Pathology and Microbiology-Immunology, The Feinberg School of Medicine, Northwestern University, 303 Chicago Avenue, Chicago, IL 60611, USA
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50
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Cortes GT, Winograd E, Wiser MF. Characterization of proteins localized to a subcellular compartment associated with an alternate secretory pathway of the malaria parasite. Mol Biochem Parasitol 2003; 129:127-35. [PMID: 12850257 DOI: 10.1016/s0166-6851(03)00097-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Monoclonal antibodies recognizing proteins localized to a unique subcellular compartment within the malaria parasite are described in this report. These monoclonal antibodies recognize Plasmodium falciparum proteins of 68, 45 and 22 kDa proteins which are also conserved in rodent Plasmodium species. Co-localization studies indicate that these proteins are located in a brefeldin A-induced compartment which was previously proposed to be an early step in the export of proteins from the parasite into the infected erythrocyte. COPII coat proteins, Sar1p and Sec31p, and the endoplasmic reticulum-associated chaperone, BiP, all partially co-localize with the 68 and 22 kDa proteins, thus suggesting that this subcellular compartment has some similarities to the endoplasmic reticulum or that this compartment represents a domain of the endoplasmic reticulum. The 68 and 22 kDa proteins are highly soluble in non-ionic detergent and are likely to be located within the lumen of a membrane-bound compartment. These proteins found within this subcellular compartment are present throughout the blood stage from very early rings to segmenters. The results of this study further substantiate the existence of an alternate secretory pathway in the malaria parasite which plays a role in the export of proteins into the host erythrocyte.
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