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Klinger CM, Jimenez-Ruiz E, Mourier T, Klingl A, Lemgruber L, Pain A, Dacks JB, Meissner M. Evolutionary analysis identifies a Golgi pathway and correlates lineage-specific factors with endomembrane organelle emergence in apicomplexans. Cell Rep 2024; 43:113740. [PMID: 38363682 DOI: 10.1016/j.celrep.2024.113740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 12/20/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024] Open
Abstract
The organelle paralogy hypothesis (OPH) aims to explain the evolution of non-endosymbiotically derived organelles. It predicts that lineage-specific pathways or organelles should result when identity-encoding membrane-trafficking components duplicate and co-evolve. Here, we investigate the presence of such lineage-specific membrane-trafficking machinery paralogs in Apicomplexa, a globally important parasitic lineage. We are able to identify 18 paralogs of known membrane-trafficking machinery, in several cases co-incident with the presence of new endomembrane organelles in apicomplexans or their parent lineage, the Alveolata. Moreover, focused analysis of the apicomplexan Arf-like small GTPases (i.e., ArlX3) revealed a specific post-Golgi trafficking pathway. This pathway appears involved in delivery of proteins to micronemes and rhoptries, with knockdown demonstrating reduced invasion capacity. Overall, our data have identified an unforeseen post-Golgi trafficking pathway in apicomplexans and are consistent with the OPH mechanism acting to produce endomembrane pathways or organelles at various evolutionary stages across the alveolate lineage.
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Affiliation(s)
- Christen M Klinger
- Division of Infectious Diseases, Department of Medicine and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Elena Jimenez-Ruiz
- Experimental Parasitology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, Germany
| | - Tobias Mourier
- Pathogen Genomics Laboratory, Bioscience Programme, Biological, and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Andreas Klingl
- Pflanzliche Entwicklungsbiologie, Biozentrum der Ludwig-Maximilians-Universität, Munich, Germany
| | - Leandro Lemgruber
- Cellular Analysis Facility, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Arnab Pain
- Pathogen Genomics Laboratory, Bioscience Programme, Biological, and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; International Institute for Zoonosis Control, GI-CoRE, Hokkaido University, Sapporo, Japan
| | - Joel B Dacks
- Division of Infectious Diseases, Department of Medicine and Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada; Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Centre for Life's Origin and Evolution, Department of Genetics, Evolution & Environment, University College London, London, UK.
| | - Markus Meissner
- Experimental Parasitology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, Germany.
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Arabiotorre A, Formanowicz M, Bankaitis VA, Grabon A. Phosphatidylinositol-4-phosphate signaling regulates dense granule biogenesis and exocytosis in Toxoplasma gondii. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523261. [PMID: 36712082 PMCID: PMC9882004 DOI: 10.1101/2023.01.09.523261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Phosphoinositide metabolism defines the foundation of a major signaling pathway that is conserved throughout the eukaryotic kingdom. The 4-OH phosphorylated phosphoinositides such as phosphatidylinositol-4-phosphate (PtdIns4P) and phosphatidylinositol-4,5-bisphosphate are particularly important molecules as these execute intrinsically essential activities required for the viability of all eukaryotic cells studied thus far. Using intracellular tachyzoites of the apicomplexan parasite Toxoplasma gondii as model for assessing primordial roles for PtdIns4P signaling, we demonstrate the presence of PtdIns4P pools in Golgi/trans-Golgi (TGN) system and in post-TGN compartments of the parasite. Moreover, we show that deficits in PtdIns4P signaling result in structural perturbation of compartments that house dense granule cargo with accompanying deficits in dense granule exocytosis. Taken together, the data report a direct role for PtdIns4P in dense granule biogenesis and exocytosis. The data further indicate that the biogenic pathway for secretion-competent dense granule formation in T. gondii is more complex than simple budding of fully matured dense granules from the TGN.
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Affiliation(s)
- Angela Arabiotorre
- Department of Cell Biology & Genetics, College of Medicine, Texas A&M Health Sciences Center, College Station, Texas 77843-1114, USA
| | - Megan Formanowicz
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Vytas A. Bankaitis
- Department of Cell Biology & Genetics, College of Medicine, Texas A&M Health Sciences Center, College Station, Texas 77843-1114, USA
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77843-2128
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-2128
| | - Aby Grabon
- Department of Cell Biology & Genetics, College of Medicine, Texas A&M Health Sciences Center, College Station, Texas 77843-1114, USA
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Griffith MB, Pearce CS, Heaslip AT. Dense granule biogenesis, secretion, and function in Toxoplasma gondii. J Eukaryot Microbiol 2022; 69:e12904. [PMID: 35302693 PMCID: PMC9482668 DOI: 10.1111/jeu.12904] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Toxoplasma gondii is an obligate intracellular parasite and the causative agent of Toxoplasmosis. A key to understanding and treating the disease lies with determining how the parasite can survive and replicate within cells of its host. Proteins released from specialized secretory vesicles, named the dense granules (DGs), have diverse functions that are critical for adapting the intracellular environment, and are thus key to survival and pathogenicity. In this review, we describe the current understanding and outstanding questions regarding dense granule biogenesis, trafficking, and regulation of secretion. In addition, we provide an overview of dense granule protein ("GRA") function upon secretion, with a focus on proteins that have recently been identified.
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Affiliation(s)
- Michael B Griffith
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Camille S Pearce
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Aoife T Heaslip
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
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Marugan-Hernandez V, Sanchez-Arsuaga G, Vaughan S, Burrell A, Tomley FM. Do All Coccidia Follow the Same Trafficking Rules? Life (Basel) 2021; 11:life11090909. [PMID: 34575057 PMCID: PMC8465013 DOI: 10.3390/life11090909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/24/2021] [Accepted: 08/27/2021] [Indexed: 01/06/2023] Open
Abstract
The Coccidia are a subclass of the Apicomplexa and include several genera of protozoan parasites that cause important diseases in humans and animals, with Toxoplasma gondii becoming the ‘model organism’ for research into the coccidian molecular and cellular processes. The amenability to the cultivation of T. gondii tachyzoites and the wide availability of molecular tools for this parasite have revealed many mechanisms related to their cellular trafficking and roles of parasite secretory organelles, which are critical in parasite-host interaction. Nevertheless, the extrapolation of the T. gondii mechanisms described in tachyzoites to other coccidian parasites should be done carefully. In this review, we considered published data from Eimeria parasites, a coccidian genus comprising thousands of species whose infections have important consequences in livestock and poultry. These studies suggest that the Coccidia possess both shared and diversified mechanisms of protein trafficking and secretion potentially linked to their lifecycles. Whereas trafficking and secretion appear to be well conversed prior to and during host-cell invasion, important differences emerge once endogenous development commences. Therefore, further studies to validate the mechanisms described in T. gondii tachyzoites should be performed across a broader range of coccidians (including T. gondii sporozoites). In addition, further genus-specific research regarding important disease-causing Coccidia is needed to unveil the individual molecular mechanisms of pathogenesis related to their specific lifecycles and hosts.
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Affiliation(s)
- Virginia Marugan-Hernandez
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
- Correspondence: ; Tel.: +44-(0)-17-0766-9445
| | - Gonzalo Sanchez-Arsuaga
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK;
| | - Alana Burrell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK;
| | - Fiona M. Tomley
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
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Carmeille R, Schiano Lomoriello P, Devarakonda PM, Kellermeier JA, Heaslip AT. Actin and an unconventional myosin motor, TgMyoF, control the organization and dynamics of the endomembrane network in Toxoplasma gondii. PLoS Pathog 2021; 17:e1008787. [PMID: 33529198 PMCID: PMC7880465 DOI: 10.1371/journal.ppat.1008787] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 02/12/2021] [Accepted: 01/07/2021] [Indexed: 12/25/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that relies on three distinct secretory organelles, the micronemes, rhoptries, and dense granules, for parasite survival and disease pathogenesis. Secretory proteins destined for these organelles are synthesized in the endoplasmic reticulum (ER) and sequentially trafficked through a highly polarized endomembrane network that consists of the Golgi and multiple post-Golgi compartments. Currently, little is known about how the parasite cytoskeleton controls the positioning of the organelles in this pathway, or how vesicular cargo is trafficked between organelles. Here we show that F-actin and an unconventional myosin motor, TgMyoF, control the dynamics and organization of the organelles in the secretory pathway, specifically ER tubule movement, apical positioning of the Golgi and post-Golgi compartments, apical positioning of the rhoptries, and finally, the directed transport of Rab6-positive and Rop1-positive vesicles. Thus, this study identifies TgMyoF and actin as the key cytoskeletal components that organize the endomembrane system in T. gondii. Endomembrane trafficking is a vital cellular process in all eukaryotic cells. In most cases the molecular motors myosin, kinesin, and dynein transport cargo including vesicles, organelles and transcripts along actin and microtubule filaments in a manner analogous to a train moving on its tracks. For the unicellular eukaryote Toxoplasma gondii, the accurate trafficking of proteins through the endomembrane system is vital for parasite survival and pathogenicity. However, the mechanisms of cargo transport in this parasite are poorly understood. In this study, we fluorescently labeled multiple endomembrane organelles and imaged their movements using live cell microscopy. We demonstrate that filamentous actin and an unconventional myosin motor named TgMyoF control both the positioning of organelles in this pathway and the movement of transport vesicles throughout the parasite cytosol. This data provides new insight into the mechanisms of cargo transport in this important pathogen and expands our understanding of the biological roles of actin in the intracellular phase of the parasite’s growth cycle.
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Affiliation(s)
- Romain Carmeille
- Department of Cell and Molecular Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Porfirio Schiano Lomoriello
- Department of Cell and Molecular Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Parvathi M. Devarakonda
- Department of Cell and Molecular Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Jacob A. Kellermeier
- Department of Cell and Molecular Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Aoife T. Heaslip
- Department of Cell and Molecular Biology, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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6
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Wang Y, Sangaré LO, Paredes-Santos TC, Saeij JPJ. Toxoplasma Mechanisms for Delivery of Proteins and Uptake of Nutrients Across the Host-Pathogen Interface. Annu Rev Microbiol 2020; 74:567-586. [PMID: 32680452 PMCID: PMC9934516 DOI: 10.1146/annurev-micro-011720-122318] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many intracellular pathogens, including the protozoan parasite Toxoplasma gondii, live inside a vacuole that resides in the host cytosol. Vacuolar residence provides these pathogens with a defined niche for replication and protection from detection by host cytosolic pattern recognition receptors. However, the limiting membrane of the vacuole, which constitutes the host-pathogen interface, is also a barrier for pathogen effectors to reach the host cytosol and for the acquisition of host-derived nutrients. This review provides an update on the specialized secretion and trafficking systems used by Toxoplasma to overcome the barrier of the parasitophorous vacuole membrane and thereby allow the delivery of proteins into the host cell and the acquisition of host-derived nutrients.
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Affiliation(s)
- Yifan Wang
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA; , , ,
| | - Lamba Omar Sangaré
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA; , , ,
| | - Tatiana C. Paredes-Santos
- Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California, Davis, Davis, California, USA
| | - Jeroen P. J. Saeij
- Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California, Davis, Davis, California, USA
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Tartarelli I, Tinari A, Possenti A, Cherchi S, Falchi M, Dubey JP, Spano F. During host cell traversal and cell-to-cell passage, Toxoplasma gondii sporozoites inhabit the parasitophorous vacuole and posteriorly release dense granule protein-associated membranous trails. Int J Parasitol 2020; 50:1099-1115. [PMID: 32882286 DOI: 10.1016/j.ijpara.2020.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/21/2020] [Accepted: 06/23/2020] [Indexed: 10/23/2022]
Abstract
Toxoplasma gondii has a worldwide distribution and infects virtually all warm-blooded animals, including humans. Ingestion of the environmentally resistant oocyst stage, excreted only in the feces of cats, is central to transmission of this apicomplexan parasite. There is vast literature on the host and T. gondii tachyzoite (proliferative stage of the parasite) but little is known of the host-parasite interaction and conversion of the free-living stage (sporozoite inside the oocyst) to the parasitic stage. Here, we present events that follow invasion of host cells with T. gondii sporozoites by using immunofluorescence (IF) and transmission electron microscopy (TEM). Several human type cell cultures were infected with T. gondii sporozoites of the two genotypes (Type II, ME49 and Type III, VEG) most prevalent worldwide. For the first known time, using anti-rhoptry neck protein 4 (RON4) antibodies, the moving junction was visualized in sporozoites during the invasion process and shortly after its completion. Surprisingly, IF and TEM evaluation revealed that intracellular sporozoites release, at their posterior end, long membranous tails, herein named sporozoite-specific trails (SSTs). Differential permeabilization and IF experiments showed that the SSTs are associated with several dense granule proteins (GRAs) and that their membranous component is of parasite origin. Furthermore, TEM observations demonstrated that SST-associated sporozoites are delimited by a typical parasitophorous vacuole, which is retained during parasite exit from the host cell and during cell-to-cell passage. Our data strongly suggest that host cell traversal by T. gondii sporozoites relies on a novel force-producing mechanism, based on the massive extrusion at the parasite posterior pole of GRA-associated membranous material derived from the same pool of membranes forming the intravacuolar network.
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Affiliation(s)
- Irene Tartarelli
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Antonella Tinari
- Center for Gender-Specific Medicine, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Alessia Possenti
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Simona Cherchi
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Mario Falchi
- National AIDS Center, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Jitender P Dubey
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland 20705, United States
| | - Furio Spano
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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The effect of edelfosine on GRA1 and MIC3 expressions in acute toxoplasmosis. Parasitol Res 2020; 119:1371-1380. [PMID: 31970471 DOI: 10.1007/s00436-020-06601-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/06/2020] [Indexed: 10/25/2022]
Abstract
Phosphoinositide-dependent phospholipase-C (PI-PLC) triggers the calcium signaling pathway which plays an important role in dense granule and microneme secretion and pathogenesis of Toxoplasma gondii (T. gondii). There are limited data about the effects of phospholipid analogues against T. gondii. The current study assessed the effect of edelfosine, as a phospholipid analogue, on GRA1 and MIC3 expressions using in vitro and in vivo models of acute toxoplasmosis. Infected Vero cells were treated by edelfosine in two subgroups: 24 h following the cell infection and treatment at the same time of cell infection. Animal study was performed on forty mice in four groups including non-infected, infected untreated, infected edelfosine-treated, and infected pyrimethamine-treated. Gene and protein expression analyses were done using quantitative real-time PCR and western blot, respectively. Edelfosine significantly reduced the GRA1 (P < 0.01) and MIC3 (P < 0.01) mRNA and protein expressions in 24 h following the cell infection and at the same time of cell infection groups. In vivo study showed that the edelfosine significantly reduced the GRA1 expression in eye, and MIC3 expression in brain and liver. Moreover, the edelfosine-treated infected mice had significant higher survival rate compared with uninfected mice. The reducing effect of edelfosine on GRA1 and MIC3 mRNA and protein levels 24 h following the cell infection was more than treatment at the same time of cell infection group. Moreover, the effect of edelfosine on GRA1 and MIC3 expression in animal tissues was variable. These data showed that the edelfosine may decrease the T. gondii excretory/secretory antigens through inhibition of PI-PLC.
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Translocation of effector proteins into host cells by Toxoplasma gondii. Curr Opin Microbiol 2019; 52:130-138. [PMID: 31446366 DOI: 10.1016/j.mib.2019.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/19/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022]
Abstract
The Apicomplexan parasite, Toxoplasma gondii, is an obligate intracellular organism that must co-opt its host cell to survive. To this end, Toxoplasma parasites introduce a suite of effector proteins from two secretory compartments called rhoptries and dense granules into the host cells. Once inside, these effectors extensively modify the host cell to facilitate parasite penetration, replication and persistence. In this review, we summarize the most recent advances in current understanding of effector translocation from Toxoplasma's rhoptry and dense granule organelles into the host cell, with comparisons to Plasmodium spp. for broader context.
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Katris NJ, Ke H, McFadden GI, van Dooren GG, Waller RF. Calcium negatively regulates secretion from dense granules in Toxoplasma gondii. Cell Microbiol 2019; 21:e13011. [PMID: 30673152 PMCID: PMC6563121 DOI: 10.1111/cmi.13011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/05/2018] [Accepted: 01/17/2019] [Indexed: 12/23/2022]
Abstract
Apicomplexan parasites including Toxoplasma gondii and Plasmodium spp. manufacture a complex arsenal of secreted proteins used to interact with and manipulate their host environment. These proteins are organised into three principle exocytotic compartment types according to their functions: micronemes for extracellular attachment and motility, rhoptries for host cell penetration, and dense granules for subsequent manipulation of the host intracellular environment. The order and timing of these events during the parasite's invasion cycle dictates when exocytosis from each compartment occurs. Tight control of compartment secretion is, therefore, an integral part of apicomplexan biology. Control of microneme exocytosis is best understood, where cytosolic intermediate molecular messengers cGMP and Ca2+ act as positive signals. The mechanisms for controlling secretion from rhoptries and dense granules, however, are virtually unknown. Here, we present evidence that dense granule exocytosis is negatively regulated by cytosolic Ca2+, and we show that this Ca2+‐mediated response is contingent on the function of calcium‐dependent protein kinases TgCDPK1 and TgCDPK3. Reciprocal control of micronemes and dense granules provides an elegant solution to the mutually exclusive functions of these exocytotic compartments in parasite invasion cycles and further demonstrates the central role that Ca2+ signalling plays in the invasion biology of apicomplexan parasites.
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Affiliation(s)
- Nicholas J Katris
- Department of Biochemistry, University of Cambridge, Cambridge, UK.,School of Biosciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Huiling Ke
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Geoffrey I McFadden
- School of Biosciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Giel G van Dooren
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Ross F Waller
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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11
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Venugopal K, Marion S. Secretory organelle trafficking in Toxoplasma gondii: A long story for a short travel. Int J Med Microbiol 2018; 308:751-760. [DOI: 10.1016/j.ijmm.2018.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/10/2018] [Accepted: 07/15/2018] [Indexed: 12/15/2022] Open
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Pastor-Fernández I, Regidor-Cerrillo J, Álvarez-García G, Marugán-Hernández V, García-Lunar P, Hemphill A, Ortega-Mora LM. The tandemly repeated NTPase (NTPDase) from Neospora caninum is a canonical dense granule protein whose RNA expression, protein secretion and phosphorylation coincides with the tachyzoite egress. Parasit Vectors 2016; 9:352. [PMID: 27329357 PMCID: PMC4915099 DOI: 10.1186/s13071-016-1620-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/01/2016] [Indexed: 12/26/2022] Open
Abstract
Background NTPases (also NTPDases) are enzymes with apyrase activity. They are widely distributed among eukaryotes, and also among members of the family Sarcocystidae. In Toxoplasma gondii, the TgNTPase accumulates in the dense granules, and has been commonly associated with the strain virulence. In the closely related Neospora caninum, the NcNTPase lacks nucleoside diphosphate hydrolase activity and appears to be more abundant in virulent isolates, indicating that it may contribute to the pathogenicity of neosporosis. However, so far no additional information on NcNTPase has been provided. Methods Herein, the NcNTPase coding sequences were analysed by different in silico and de novo sequencing approaches. A comparative analysis of NcNTPase and NcGRA7 in terms of protein dynamics, secretion, phosphorylation, and mRNA expression profiles during the tachyzoite lytic cycle was also carried out. Moreover, NcNTPase immunolocalization was analysed by confocal microscopy techniques over a set number of time-points. Results We describe the presence of three different loci containing three copies of the NcNTPase within the Nc-Liv genome, and report the existence of up to four different NcNTPase alleles in Nc-Liv. We also provide evidence for the occurrence of diverse protein species of the NcNTPase by two-dimensional gel electrophoresis. Both NcNTPase and NcGRA7 were similarly up-regulated and secreted during the egress and/or early invasion phases, and were phosphorylated. However, its secretion was not affected by the addition of calcium modulators such as A23187 and ethanol. NcNTPase and NcGRA7 localized in dense granules and parasitophorous vacuole membrane throughout the lytic cycle, although differed in their inmunolocalization during early invasion and egress. Conclusions The present study reveals the complexity of the NcNTPase loci in N. caninum. We hypothesize that the expression of different isoforms of the NcNTPase protein could contribute to parasite virulence. Our findings showed regulation of expression, secretion and phosphorylation of NcNTPase suggesting a potential role for progression through the tachyzoites lytic cycle. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1620-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Iván Pastor-Fernández
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Javier Regidor-Cerrillo
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Gema Álvarez-García
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Virginia Marugán-Hernández
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Paula García-Lunar
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012, Berne, Switzerland
| | - Luis M Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
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13
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Leroux LP, Dasanayake D, Rommereim LM, Fox BA, Bzik DJ, Jardim A, Dzierszinski FS. Secreted Toxoplasma gondii molecules interfere with expression of MHC-II in interferon gamma-activated macrophages. Int J Parasitol 2015; 45:319-32. [PMID: 25720921 DOI: 10.1016/j.ijpara.2015.01.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 01/16/2015] [Accepted: 01/18/2015] [Indexed: 11/15/2022]
Abstract
The obligate intracellular protozoan parasite Toxoplasma gondii interferes with major histocompatibility complex class II antigen presentation to dampen host CD4(+) T cell responses. While it is known that T. gondii inhibits major histocompatibility complex class II gene transcription and expression in infected host cells, the mechanism of this host manipulation is unknown. Here, we show that soluble parasite proteins inhibit IFNγ-induced expression of major histocompatibility complex class II on the surface of the infected cell in a dose-dependent response that was abolished by protease treatment. Subcellular fractionation of T. gondii tachyzoites revealed that the major histocompatibility complex class II inhibitory activity co-partitioned with rhoptries and/or dense granules. However, parasite mutants deleted for single rhoptries or dense granules genes (ROP1, 4/7, 14, 16 and 18 or GRA 2-9 and 12 knock-out strains) retained the ability to inhibit expression of major histocompatibility complex class II. In addition, excreted/secreted antigens released by extracellular tachyzoites displayed immunomodulatory activity characterized by an inhibition of major histocompatibility complex class II expression, and reduced expression and release of TNFα by macrophages. Tandem MS analysis of parasite excreted/secreted antigens generated a list of T. gondii secreted proteins that may participate in major histocompatibility complex class II inhibition and the modulation of host immune functions.
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Affiliation(s)
- Louis-Philippe Leroux
- Institute of Parasitology, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; Centre for Host-Parasite Interaction, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Dayal Dasanayake
- Institute of Parasitology, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; Centre for Host-Parasite Interaction, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Leah M Rommereim
- Geisel School of Medicine at Dartmouth, Borwell Research Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Barbara A Fox
- Geisel School of Medicine at Dartmouth, Borwell Research Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - David J Bzik
- Geisel School of Medicine at Dartmouth, Borwell Research Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Armando Jardim
- Institute of Parasitology, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; Centre for Host-Parasite Interaction, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada.
| | - Florence S Dzierszinski
- Institute of Parasitology, McGill University, Parasitology Building, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; Carleton University Research Office, Dunton Tower, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
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Lige B, Romano JD, Sampels V, Sonda S, Joiner KA, Coppens I. Introduction of caveolae structural proteins into the protozoan Toxoplasma results in the formation of heterologous caveolae but not caveolar endocytosis. PLoS One 2012; 7:e51773. [PMID: 23272165 PMCID: PMC3522706 DOI: 10.1371/journal.pone.0051773] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/08/2012] [Indexed: 11/30/2022] Open
Abstract
Present on the plasma membrane of most metazoans, caveolae are specialized microdomains implicated in several endocytic and trafficking mechanisms. Caveolins and the more recently discovered cavins are the major protein components of caveolae. Previous studies reported that caveolar invaginations can be induced de novo on the surface of caveolae-negative mammalian cells upon heterologous expression of caveolin-1. However, it remains undocumented whether other components in the transfected cells participate in caveolae formation. To address this issue, we have exploited the protozoan Toxoplasma as a heterologous expression system to provide insights into the minimal requirements for caveogenesis and caveolar endocytosis. Upon expression of caveolin-1, Toxoplasma accumulates prototypical exocytic caveolae 'precursors' in the cytoplasm. Toxoplasma expressing caveolin-1 alone, or in conjunction with cavin-1, neither develops surface-located caveolae nor internalizes caveolar ligands. These data suggest that the formation of functional caveolae at the plasma membrane in Toxoplasma and, by inference in all non-mammalian cells, requires effectors other than caveolin-1 and cavin-1. Interestingly, Toxoplasma co-expressing caveolin-1 and cavin-1 displays an impressive spiraled network of membranes containing the two proteins, in the cytoplasm. This suggests a synergistic activity of caveolin-1 and cavin-1 in the morphogenesis and remodeling of membranes, as illustrated for Toxoplasma.
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Affiliation(s)
- Bao Lige
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health Baltimore, Maryland, United States of America
| | - Julia D. Romano
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health Baltimore, Maryland, United States of America
| | - Vera Sampels
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health Baltimore, Maryland, United States of America
| | - Sabrina Sonda
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Keith A. Joiner
- Arizona Health Science Center, University of Arizona College of Medicine, Tucson, Arizona, United States of America
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health Baltimore, Maryland, United States of America
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15
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Sloves PJ, Delhaye S, Mouveaux T, Werkmeister E, Slomianny C, Hovasse A, Dilezitoko Alayi T, Callebaut I, Gaji R, Schaeffer-Reiss C, Van Dorsselear A, Carruthers V, Tomavo S. Toxoplasma Sortilin-like Receptor Regulates Protein Transport and Is Essential for Apical Secretory Organelle Biogenesis and Host Infection. Cell Host Microbe 2012; 11:515-27. [DOI: 10.1016/j.chom.2012.03.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 02/02/2012] [Accepted: 03/28/2012] [Indexed: 12/16/2022]
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16
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Dynamics and 3D organization of secretory organelles of Toxoplasma gondii. J Struct Biol 2012; 177:420-30. [DOI: 10.1016/j.jsb.2011.11.028] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 11/21/2011] [Accepted: 11/28/2011] [Indexed: 11/23/2022]
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17
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Toxoplasma gondii cyclophilin 18 regulates the proliferation and migration of murine macrophages and spleen cells. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:1322-9. [PMID: 20660134 DOI: 10.1128/cvi.00128-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Toxoplasma gondii is an intracellular parasite that shows a unique capacity to infect a variety of cell types in warm-blooded animals. It can invade and survive well inside immune cells, such as macrophages, that disseminate the parasite around the body because of their migratory properties. The aim of the present study was to evaluate the role of T. gondii cyclophilin 18 (TgCyp18) in the proliferation and migration of macrophages and spleen cells (mainly T lymphocytes) in order to understand the effects of TgCyp18 on the dynamics of the infection. A high dose of TgCyp18 enhanced the proliferation of macrophages and spleen cells in a cysteine-cysteine chemokine receptor 5 (CCR5)-independent way. In contrast, TgCyp18 controlled the migration of macrophages and spleen cells in dose- and CCR5-dependent manners. Our data suggest that TgCyp18 recruits cells and enhances the growth of host cells at the site of infection for maintenance of the interaction between the parasite and host.
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18
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Nam HW. GRA proteins of Toxoplasma gondii: maintenance of host-parasite interactions across the parasitophorous vacuolar membrane. THE KOREAN JOURNAL OF PARASITOLOGY 2010; 47 Suppl:S29-37. [PMID: 19885333 DOI: 10.3347/kjp.2009.47.s.s29] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 09/28/2009] [Accepted: 09/28/2009] [Indexed: 01/23/2023]
Abstract
The dense granule of Toxoplasma gondii is a secretory vesicular organelle of which the proteins participate in the modification of the parasitophorous vacuole (PV) and PV membrane for the maintenance of intracellular parasitism in almost all nucleated host cells. In this review, the archives on the research of GRA proteins are reviewed on the foci of finding GRA proteins, characterizing molecular aspects, usefulness in diagnostic antigen, and vaccine trials in addition to some functions in host-parasite interactions.
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Affiliation(s)
- Ho-Woo Nam
- Department of Parasitology, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
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19
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Flow cytometric assessment of distinct physiological stages withinCryptosporidium parvumsporozoites post-excystation. Parasitology 2009; 136:953-66. [DOI: 10.1017/s0031182009006519] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYCryptosporidium parvumare protozoan parasites responsible for outbreaks of gastrointestinal disease worldwide. Within the apical complex of this organism reside numerous vesicular secretory organelles and their discharge has been identified as essential for sporozoite motility, cell attachment and penetration. Traditionally, investigation of apical organelle discharge has relied on microscopic and immunochemical hybridization techniques. In this study we demonstrate for the first time how flow cytometry, in combination with vital dye staining, provides an avenue for discrimination of distinct physiological events occurring withinCryptosporidiumsporozoites post-excystation. Time-course studies of freshly excysted sporozoites were carried out at 37°C in cell-free medium, stained with the fluorescent dyes SYTO9/PI, DiBAC4(3), Fluo-4 AM or FM1-43 and analysed by flow cytometry. Significant decreases in sporozoite plasma membrane permeability and increased membrane depolarization were found to be accompanied by concomitant increases in intracellular calcium. Subsequent to these changes, large increases in exocytosed vesicular membrane were apparent. In addition, by measuring side and forward angle light scatter we were able to assess changes in internal granularity and size of sporozoites post-excystation. These observations were suggestive of rapid mobilization, utilization and discharge of apical organelles within sporozoites, which we relate to changes in sporozoite infectivity, ATP levels and total secreted soluble protein.
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20
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Elias EV, Quiroga R, Gottig N, Nakanishi H, Nash TE, Neiman A, Lujan HD. Characterization of SNAREs determines the absence of a typical Golgi apparatus in the ancient eukaryote Giardia lamblia. J Biol Chem 2008; 283:35996-6010. [PMID: 18930915 DOI: 10.1074/jbc.m806545200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Giardia is a eukaryotic protozoal parasite with unusual characteristics, such as the absence of a morphologically evident Golgi apparatus. Although both constitutive and regulated pathways for protein secretion are evident in Giardia, little is known about the mechanisms involved in vesicular docking and fusion. In higher eukaryotes, soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) of the vesicle-associated membrane protein and syntaxin families play essential roles in these processes. In this work we identified and characterized genes for 17 SNAREs in Giardia to define the minimal set of subcellular organelles present during growth and encystation, in particular the presence or not of a Golgi apparatus. Expression and localization of all Giardia SNAREs demonstrate their presence in distinct subcellular compartments, which may represent the extent of the endomembrane system in eukaryotes. Remarkably, Giardia SNAREs, homologous to Golgi SNAREs from other organisms, do not allow the detection of a typical Golgi apparatus in either proliferating or differentiating trophozoites. However, some features of the Golgi, such as the packaging and sorting function, seem to be performed by the endoplasmic reticulum and/or the nuclear envelope. Moreover, depletion of individual genes demonstrated that several SNAREs are essential for viability, whereas others are dispensable. Thus, Giardia requires a smaller number of SNAREs compared with other eukaryotes to accomplish all of the vesicle trafficking events that are critical for the growth and differentiation of this important human pathogen.
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Affiliation(s)
- Eliana V Elias
- Laboratory of Biochemistry and Molecular Biology, School of Medicine, Catholic University of Cordoba/National Council for Science and Technology, Cordoba CP X5004ASK, Argentina
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21
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The Toxoplasma gondii dense granule protein GRA7 is phosphorylated upon invasion and forms an unexpected association with the rhoptry proteins ROP2 and ROP4. Infect Immun 2008; 76:5853-61. [PMID: 18809661 DOI: 10.1128/iai.01667-07] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii infects warm-blooded animals throughout the world and is an opportunistic pathogen of humans. As it invades a host cell, Toxoplasma forms a novel organelle, the parasitophorous vacuole, in which it resides during its intracellular development. The parasite modifies the parasitophorous vacuole and its host cell with numerous proteins delivered from rhoptries and dense granules, which are secretory organelles unique to the phylum Apicomplexa. For the majority of these proteins, little is known other than their localization. Here we show that the dense granule protein GRA7 is phosphorylated but only in the presence of host cells. Within 10 min of invasion, GRA7 is present in strand-like structures in the host cytosol that contain rhoptry proteins. GRA7 strands also contain GRA1 and GRA3. Independently of its phosphorylation state, GRA7 associates with the rhoptry proteins ROP2 and ROP4 in infected host cells. This is the first report of interactions between proteins secreted from rhoptries and dense granules.
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22
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23
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A transient forward-targeting element for microneme-regulated secretion in Toxoplasma gondii. Biol Cell 2008; 100:253-64. [PMID: 17995454 DOI: 10.1042/bc20070076] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION Accurate sorting of proteins to the three types of secretory granules in Toxoplasma gondii is crucial for successful cell invasion by this obligate intracellular parasite. As in other eukaryotic systems, propeptide sequences are a common yet poorly understood feature of proteins destined for regulated secretion, which for Toxoplasma occurs through two distinct invasion organelles, rhoptries and micronemes. Microneme discharge during parasite apical attachment plays a pivotal role in cell invasion by delivering adhesive proteins for host receptor engagement. RESULTS We show here that the small micronemal proprotein MIC5 (microneme protein-5) undergoes proteolytic maturation at a site beyond the Golgi, and only the processed form of MIC5 is secreted via the micronemes. Proper cleavage of the MIC5 propeptide relies on an arginine residue in the P1' position, although P1' mutants are still cleaved to a lesser extent at an alternative site downstream of the primary site. Nonetheless, this aberrantly cleaved species still correctly traffics to the micronemes, indicating that correct cleavage is not necessary for micronemal targeting. In contrast, a deletion mutant lacking the propeptide was retained within the secretory system, principally in the ER (endoplasmic reticulum). The MIC5 propeptide also supported correct trafficking when exchanged for the M2AP propeptide, which was recently shown to also be required for micronemal trafficking of the TgMIC2 (T. gondii MIC2)-M2AP complex [Harper, Huynh, Coppens, Parussini, Moreno and Carruthers (2006) Mol. Biol. Cell 17, 4551-4563]. CONCLUSION Our results illuminate common and unique features of micronemal propeptides in their role as trafficking facilitators.
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24
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Kawase O, Nishikawa Y, Bannai H, Zhang H, Zhang G, Jin S, Lee EG, Xuan X. Proteomic analysis of calcium-dependent secretion in Toxoplasma gondii. Proteomics 2007; 7:3718-25. [PMID: 17880006 DOI: 10.1002/pmic.200700362] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Toxoplasma gondii is an intracellular protozoan parasite that invades a wide range of nucleated cells. In the course of intracellular parasitism, the parasite releases a large variety of proteins from three secretory organelles, namely, micronemes, rhoptries and dense granules. Elevation of intracellular Ca(2+) in the parasite causes microneme discharge, and microneme secretion is essential for the invasion. In this study, we performed a proteomic analysis of the Ca(2+)-dependent secretion to evaluate the protein repertoire. We found that Ca(2+)-mobilising agents, such as thapsigargin, NH(4)Cl, ethanol and a Ca(2+) ionophore, A23187, promoted the secretion of the parasite proteins. The proteins, artificially secreted by A23187, were used in a comparative proteomic analysis by 2-DE followed by PMF analysis and/or N-terminal sequencing. Major known microneme proteins (MICs), such as MIC2, MIC4, MIC6 and MIC10 and apical membrane antigen 1 (AMA1), were identified, indicating that the proteomic analysis worked accurately. Interestingly, new members of secretory proteins, namely rhoptry protein 9 (ROP9) and Toxoplasma SPATR (TgSPATR), which was a homologue of a Plasmodium secreted protein with an altered thrombospondin repeat (SPATR), were detected in Ca(2+)-dependent secretion. Thus, we succeeded in detecting Ca(2+)-dependent secretory proteins in T. gondii, which contained novel secretory proteins.
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Affiliation(s)
- Osamu Kawase
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
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25
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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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26
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Tonkin CJ, Pearce JA, McFadden GI, Cowman AF. Protein targeting to destinations of the secretory pathway in the malaria parasite Plasmodium falciparum. Curr Opin Microbiol 2006; 9:381-7. [PMID: 16828333 DOI: 10.1016/j.mib.2006.06.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Accepted: 06/26/2006] [Indexed: 11/23/2022]
Abstract
The secretory pathway in the malaria parasite Plasmodium falciparum has many unique aspects in terms of protein destinations and trafficking mechanisms. Recently, several exciting insights into protein trafficking within this intracellular parasite have been unveiled: these include signals that are required for targeting of proteins to the red blood cell and the relict plastid (known as the apicoplast); and the elucidation of the pathways of the haemoglobin proteases targeted to the food vacuole. Protein-targeting to the apical organelles in P. falciparum, however, is still not very well understood, but available research offers a tantalising glimpse of the system.
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Affiliation(s)
- Christopher J Tonkin
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Australia
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27
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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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28
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Pfluger SL, Goodson HV, Moran JM, Ruggiero CJ, Ye X, Emmons KM, Hager KM. Receptor for retrograde transport in the apicomplexan parasite Toxoplasma gondii. EUKARYOTIC CELL 2005; 4:432-42. [PMID: 15701805 PMCID: PMC549326 DOI: 10.1128/ec.4.2.432-442.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Toxoplasma gondii and its apicomplexan relatives (such as Plasmodium falciparum, which causes malaria) are obligate intracellular parasites that rely on sequential protein release from specialized secretory organelles for invasion and multiplication within host cells. Because of the importance of these unusual membrane trafficking pathways for drug development and comparative cell biology, characterizing them is essential. In particular, it is unclear what role retrieval mechanisms play in parasite membrane trafficking or where they operate. Previously, we showed that T. gondii's beta-COP (TgBetaCOP; a subunit of coatomer protein complex I, COPI) and retrieval reporters localize exclusively to the zone between the parasite endoplasmic reticulum (ER) and Golgi apparatus. This suggested the existence of an HDEL receptor in T. gondii. We have now identified, cloned, and sequenced this receptor, TgERD2. TgERD2 localizes in a Golgi or ER pattern suggestive of the HDEL retrieval reporter (K. M. Hager, B. Striepen, L. G. Tilney, and D. S. Roos, J. Cell Sci. 112:2631-2638, 1999). A functional assay reveals that TgERD2 is able to complement the Saccharomyces cerevisiae ERD2 null mutant. Retrieval studies reveal that stable expression of a fluorescent exogenous retrieval ligand results in a dispersal of betaCOP signal throughout the cytoplasm and, surprisingly, results in betaCOP staining of the vacuolar space of the parasite. In contrast, stable expression of TgERD2GFP does not appear to disturb betaCOP staining. In addition to TgERD2, Toxoplasma contains two more divergent ERD2 relatives. Phylogenetic analysis reveals that these proteins belong to a previously unrecognized ERD2 subfamily common to plants and alveolate organisms and as such could represent mediators of parasite-specific retrieval functions. No evidence of class 2 ERD2 proteins was found in metazoan organisms or fungi.
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Affiliation(s)
- Stacy L Pfluger
- Department of Biological Sciences, Center for Tropical Disease Research and Training, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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29
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Ahn HJ, Kim S, Nam HW. Host cell binding of GRA10, a novel, constitutively secreted dense granular protein from Toxoplasma gondii. Biochem Biophys Res Commun 2005; 331:614-20. [PMID: 15850804 DOI: 10.1016/j.bbrc.2005.03.218] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2005] [Indexed: 11/24/2022]
Abstract
Monoclonal antibodies (mAbs) against Toxoplasma gondii, Tg378 and Tg556 clones, are specifically observed to localize to the dense granules of tachyzoites by immunofluorescence microscopy. mAb Tg556 is directed against GRA3, a previously described 30kDa dense granular protein. mAb Tg378 is directed against a novel 36kDa dense granular protein, which we refer to as GRA10. These are major proteins in the excretory/secretory proteins from T. gondii before the parasite's entry into host cells, and they are released into the parasitophorous vacuole (PV) during or shortly after invasion to be associated with the PV membrane. GRA10 binds to the membrane of the host cells regardless of its anchorage-dependence or -independence. The cDNA sequence encoding GRA10 was determined by screening a T. gondii cDNA expression library with mAb Tg378. The deduced amino acid sequence of GRA10 consists of a polypeptide of 364 amino acids, and it has no significant homology to any other known proteins. The sequence contains amino terminal signal peptides and two potential transmembrane domains in the middle of sequence that are not near the carboxy terminus. GRA10 has a RGD motif between the two potential transmembrane domains.
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Affiliation(s)
- Hye-Jin Ahn
- Department of Parasitology, Catholic Institute of Parasitic Diseases, College of Medicine, Catholic University of Korea, Seoul 137-701, Republic of Korea
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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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31
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Xu P, Widmer G, Wang Y, Ozaki LS, Alves JM, Serrano MG, Puiu D, Manque P, Akiyoshi D, Mackey AJ, Pearson WR, Dear PH, Bankier AT, Peterson DL, Abrahamsen MS, Kapur V, Tzipori S, Buck GA. The genome of Cryptosporidium hominis. Nature 2004; 431:1107-12. [PMID: 15510150 DOI: 10.1038/nature02977] [Citation(s) in RCA: 390] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Accepted: 08/06/2004] [Indexed: 11/09/2022]
Abstract
Cryptosporidium species cause acute gastroenteritis and diarrhoea worldwide. They are members of the Apicomplexa--protozoan pathogens that invade host cells by using a specialized apical complex and are usually transmitted by an invertebrate vector or intermediate host. In contrast to other Apicomplexans, Cryptosporidium is transmitted by ingestion of oocysts and completes its life cycle in a single host. No therapy is available, and control focuses on eliminating oocysts in water supplies. Two species, C. hominis and C. parvum, which differ in host range, genotype and pathogenicity, are most relevant to humans. C. hominis is restricted to humans, whereas C. parvum also infects other mammals. Here we describe the eight-chromosome approximately 9.2-million-base genome of C. hominis. The complement of C. hominis protein-coding genes shows a striking concordance with the requirements imposed by the environmental niches the parasite inhabits. Energy metabolism is largely from glycolysis. Both aerobic and anaerobic metabolisms are available, the former requiring an alternative electron transport system in a simplified mitochondrion. Biosynthesis capabilities are limited, explaining an extensive array of transporters. Evidence of an apicoplast is absent, but genes associated with apical complex organelles are present. C. hominis and C. parvum exhibit very similar gene complements, and phenotypic differences between these parasites must be due to subtle sequence divergence.
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Affiliation(s)
- Ping Xu
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284-2030, USA
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32
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Binder EM, Kim K. Location, Location, Location: Trafficking and Function of Secreted Proteases of Toxoplasma and Plasmodium. Traffic 2004; 5:914-24. [PMID: 15522094 DOI: 10.1111/j.1600-0854.2004.00244.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Apicomplexan parasites Toxoplasma gondii and Plasmodium species are obligate intracellular parasites that rely upon unique secretory organelles for invasion and other specialized functions. Data is emerging that proteases are critical for the biogenesis of micronemes and rhoptries, regulated secretory organelles reminiscent of dense core granules and secretory lysosomes of higher eukaryotes. Proteases targeted to the Plasmodium food vacuole, a unique organelle dedicated to hemoglobin degradation, are also critical to parasite survival. Thus study of the targeting and function of the proteases of the Apicomplexa provides a fascinating model system to understand regulated secretion and secretory organelle biogenesis.
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Affiliation(s)
- Emily M Binder
- Departments of Medicine and of Microbiology and Immunology, Albert Einstein College of Medicine, Ullmann 1225, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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33
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Adjogble KDZ, Mercier C, Dubremetz JF, Hucke C, Mackenzie CR, Cesbron-Delauw MF, Däubener W. GRA9, a new Toxoplasma gondii dense granule protein associated with the intravacuolar network of tubular membranes. Int J Parasitol 2004; 34:1255-64. [PMID: 15491588 DOI: 10.1016/j.ijpara.2004.07.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Revised: 07/23/2004] [Accepted: 07/29/2004] [Indexed: 10/26/2022]
Abstract
Important components of the parasitophorous vacuole in which the intracellular protozoan parasite Toxoplasma gondii develops, comprise proteins secreted from apicomplexan specific secretory organelles named the dense granules. Here, we confirm by immunofluorescence and by cryo-electron microscopy that the recently isolated B10 protein (318 amino acids, 41kDa) is a new dense granule protein that should now be referred to as GRA9. Within the vacuolar compartment, GRA9, like GRA2, GRA4 and GRA6, associates with the network of tubular membranes connected to the parasitophorous vacuole delimiting membrane. Like the other GRA proteins, GRA9 is secreted into the vacuole from the anterior end of the parasite. However, unlike GRA2 or GRA6, GRA9 does not transit by the posterior invaginated pocket of the parasite where the network first assembles. Within the dense granules, GRA9 exists in both a soluble and an insoluble state. Like the other GRA proteins, GRA9 is secreted as a soluble form only and like most of the GRA proteins, two forms of GRA9 of the similar molecular weight are detected within the vacuolar space: a soluble form and a membrane associated form. The dual properties of GRA9 are not only ascribed by the presence of amphipathic and hydrophobic alpha-helices but also by the fact that the protein is mainly hydrophilic.
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Affiliation(s)
- Koku D Z Adjogble
- Institute for Medical Microbiology and Virology, Universitätstr. 1, D-40225 Düsseldorf, Germany
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34
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Kim K. Role of proteases in host cell invasion by Toxoplasma gondii and other Apicomplexa. Acta Trop 2004; 91:69-81. [PMID: 15158690 DOI: 10.1016/j.actatropica.2003.11.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2003] [Accepted: 11/06/2003] [Indexed: 10/26/2022]
Abstract
The process of invasion by apicomplexan parasites is a carefully coordinated process involving the regulated release of specialized secretory organelles. Several lines of evidence suggest that proteases are critical for the assembly and trafficking of organellar content proteins. Further, invasion is accompanied by cleavage and shedding of secreted proteins as host cell invasion occurs. Recent studies in Toxoplasma gondii and other Apicomplexa have led to the identification of proteases that may mediate these processing events. Among these are subtilases, subtilisin-like serine proteinases that have essential roles in processing of secreted proteins in prokaryotes and eukaryotes. Other studies suggest that cysteine proteinases or rhomboid proteases, a newly described class of serine proteinases, may be important. In addition to providing insights into the invasion process, characterization of invasion proteases may lead to identification of novel targets for antiparasitic chemotherapy.
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Affiliation(s)
- Kami Kim
- Department of Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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35
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Nishikawa Y, Xuenan X, Makala L, Vielemeyer O, Joiner KA, Nagasawa H. Characterisation of Toxoplasma gondii engineered to express mouse interferon-gamma. Int J Parasitol 2004; 33:1525-35. [PMID: 14572515 DOI: 10.1016/s0020-7519(03)00204-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recent studies have shown the feasibility of using Toxoplasma gondii as an expression system for heterologous protein. For better understanding of the mechanism of interferon-gamma (IFN-gamma) dependent immunity to T. gondii, the parasites were stably transfected with IFN-gamma gene, under control of the GRA1 promoter. Immunofluorescence analyses showed that recombinant mouse IFN-gamma localised to discrete punctuate structures consistent with dense granules and secreted into the vacuolar space. The production of IFN-gamma was detectable in both extracellular parasites and the parasite-infected cells. Growth of the recombinant parasites was inhibited in the mouse macrophage cell line (J774A.1 cells), but not in monkey kidney adherent fibroblasts (Vero cells), demonstrating the species-specificity of IFN-gamma. Addition of anti-mouse IFN-gamma antibody resulted in growth recovery of the recombinant parasites, suggesting that IFN-gamma, secreted from the parasitised host cells across the parasitophorous vacuole membrane, acted in a paracrine manner. Reverse transcription (RT)-PCR analysis revealed significant expression of inducible nitric oxide synthase mRNA and high levels of nitric oxide production in recombinant parasite-infected J774A.1 cells. A competitive inhibitor of the L-arginine-dependent effector pathway, N(G)-monomethyl-L-arginine, inhibited the reduction of recombinant parasite growth in J774A.1 cells. Taken together, our data suggest that the T. gondii expression system may provide a new tool for cytokine gene expression and that parasites engineered to express a cytokine gene may be rationally designed for use in studies on immune responses to T. gondii.
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Affiliation(s)
- Yoshifumi Nishikawa
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
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36
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Singh SB, Tandon R, Krishnamurthy G, Vikram R, Sharma N, Basu SK, Mukhopadhyay A. Rab5-mediated endosome-endosome fusion regulates hemoglobin endocytosis in Leishmania donovani. EMBO J 2003; 22:5712-22. [PMID: 14592970 PMCID: PMC275414 DOI: 10.1093/emboj/cdg557] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2002] [Revised: 06/06/2003] [Accepted: 09/11/2003] [Indexed: 11/13/2022] Open
Abstract
To understand the trafficking of endocytosed hemoglobin (Hb) in Leishmania, we investigated the characteristics of in vitro fusion between endosomes containing biotinylated Hb (BHb) and avidin-horseradish peroxidase (AHRP). We showed that early endosome fusion in Leishmania is temperature and cytosol dependent and is inhibited by ATP depletion, ATPgammaS, GTPgammaS and N-ethylmaleimide treatment. The Rab5 homolog from Leishmania donovani, LdRab5, was cloned and expressed. Our results showed that homotypic fusion between the early endosomes in Leishmania is Rab5 dependent. Early endosomes containing BHb fused efficiently with late endosomes in a process regulated by Rab7, whereas no fusion between early and late endosomes was detected using fluid phase markers. Pre-treatment of early endosomes containing BHb with monoclonal antibody specific for the C-terminus of the Hb receptor (HbR) or the addition of the C-terminal cytoplasmic fragment of the HbR specifically inhibited the fusion with late endosomes, suggesting that signal(s) mediated through the HbR cytoplasmic tail promotes the fusion of early endosomes containing Hb with late endosomes.
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Affiliation(s)
- Sudha B Singh
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
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37
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Stedman TT, Sussmann AR, Joiner KA. Toxoplasma gondii Rab6 mediates a retrograde pathway for sorting of constitutively secreted proteins to the Golgi complex. J Biol Chem 2003; 278:5433-43. [PMID: 12468555 DOI: 10.1074/jbc.m209390200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Toxoplasma gondii relies on protein secretion from specialized organelles for invasion of host cells and establishment of a parasitophorous vacuole. We identify T. gondii Rab6 as a regulator of protein transport between post-Golgi dense granule organelles and the Golgi. Toxoplasma Rab6 was localized to cisternal rims of the late Golgi and trans-Golgi network, associated transport vesicles, and microdomains of dense granule and endosomal membranes. Overexpression of wild-type Rab6 or GTP-activated Rab6(Q70L) rerouted soluble dense granule secretory proteins to the Golgi and endoplasmic reticulum and augmented the effect of brefeldin A on Golgi resorption to the endoplasmic reticulum. Parasites expressing a nucleotide-free (Rab6(N124I)) or a GDP-bound (Rab6(T25N)) mutant accumulated dense granule proteins in the Golgi and associated transport vesicles and displayed reduced secretion of GRA4 and a delay in glycosylation of GRA2. Activated Rab6 on Golgi membranes colocalized with centrin during mitosis, and parasite clones expressing Rab6 mutants displayed a partial shift in cytokinesis from endodyogeny (formation of two daughter cells) to endopolygeny (multiple daughter cells). We propose that Toxoplasma Rab6 regulates retrograde transport from post-Golgi secretory granules to the parasite Golgi.
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Affiliation(s)
- Timothy T Stedman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8022, USA.
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38
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Abstract
Name a single-celled eukaryote that boasts a small genome size, is easily cultivated in haploid form, for which a wide variety of molecular genetic tools are available, and that exhibits a simple, polarized secretory apparatus with a well-defined endoplasmic reticulum and Golgi that can serve as a model for understanding secretion. Got it? Now name a cell with all these attributes that contains at least a dozen distinct and morphologically well-defined intracellular organelles, including three distinct types of secretory vesicles and two endosymbiotic organelles. Not so sure anymore?
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Affiliation(s)
- Keith A Joiner
- Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520, USA.
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39
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Matthiesen SH, Shenoy SM, Kim K, Singer RH, Satir BH. A parafusin-related Toxoplasma protein in Ca2+-regulated secretory organelles. Eur J Cell Biol 2001; 80:775-83. [PMID: 11831391 DOI: 10.1078/0171-9335-00214] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We cloned a gene, PRPI, of Toxoplasma gondii encoding a 637-amino-acids protein having a calculated mass of 70 kDa. The sequence showed high homology to parafusin, a protein that in Paramecium tetraurelia participates in Ca2+-regulated exocytosis and is a paralog of phosphoglucomutase. We show that Toxoplasma gondii homogenate and an expressed recombinant PRP1 fusion protein cross-react with a specific peptide-derived antibody to parafusin in Western blots. Antibodies to the recombinant PRP1 showed cross-reaction with parafusin and recognized PRP1, as bands at M, 63 x 10(3) and 68 x 10(3), respectively. PRP1 is labeled when Toxoplasma gondii cells are incubated with inorganic 32P and appears as the major band on autoradiograms of SDS-PAGE gels. The localization of PRP1 was examined in secretory organelles of Toxoplasma gondii by deconvolution light microscopy followed by three dimensional reconstruction using pairwise combinations of specific antibodies. PRP1 localized to the apical third of the cell. It co-localized with micronemes, the only secretory organelle the secretion of which is Ca2+ dependent. Quantification of the co-localized stain suggests that only mature micronemes ready for exocytosis have PRP1. These findings suggest that PRP1, parafusin and other members of the phosphoglucomutase superfamily have a conserved role in Ca2+-regulated exocytic processes.
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Affiliation(s)
- S H Matthiesen
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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40
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Nischik N, Schade B, Dytnerska K, Długońska H, Reichmann G, Fischer HG. Attenuation of mouse-virulent Toxoplasma gondii parasites is associated with a decrease in interleukin-12-inducing tachyzoite activity and reduced expression of actin, catalase and excretory proteins. Microbes Infect 2001; 3:689-99. [PMID: 11489417 DOI: 10.1016/s1286-4579(01)01425-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Determinants of Toxoplasma gondii virulence are still unknown, although genetic markers associated with T. gondii pathogenicity or host susceptibility to infection have been identified. To define indicator proteins of mouse virulence, type I strain parasites were attenuated by continuous passage in fibroblast culture and compared with the parental strain passaged in mice. The loss of acute virulence, evident by a 1000-fold higher pathogen dose causing 100% lethality in mice correlated with a less efficient infection of inflammatory cells at the site of inoculation, while parasite proliferation and invasiveness in vitro proved unimpaired. Infection with the attenuated parasites elicited earlier local interleukin-12 and strong interferon-gamma responses in vivo, although the activity that triggers interleukin-12 secretion in macrophages is reduced in the attenuated compared to the virulent strain variant. The interleukin-12-inducing T. gondii stimulus was identified as a protein(s) present in tachyzoite excretory products. Comparative proteome analysis combined with immunodetection and quantitation of a variety of T. gondii antigens indicated that the steady-state levels of actin, catalase, microneme protein 5, as well as dense granule proteins 1, 2, 3, 4, 5, 7, 8 and nucleoside triphosphate hydrolase 1 are decreased in the attenuated phenotype, whereas the surface antigen 1 and rhoptry protein 1 are produced at a similar level by virulent and attenuated parasites. In conclusion, these findings reveal a correlation between the efficient establishment of T. gondii infection in vivo and parasite synthesis of actin, catalase and several excretory proteins, and thus postulate a role for these molecules in acute virulence.
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Affiliation(s)
- N Nischik
- Institute for Medical Microbiology and Virology, Heinrich-Heine-University, Universitätsstrasse 1 Geb. 22.21, 40225 Düsseldorf, Germany
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41
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Liendo A, Stedman TT, Ngo HM, Chaturvedi S, Hoppe HC, Joiner KA. Toxoplasma gondii ADP-ribosylation factor 1 mediates enhanced release of constitutively secreted dense granule proteins. J Biol Chem 2001; 276:18272-81. [PMID: 11278405 DOI: 10.1074/jbc.m008352200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Toxoplasma gondii dense granules are morphologically similar to dense matrix granules in specialized secretory cells, yet are secreted in a constitutive, calcium-independent fashion. We previously demonstrated that secretion of dense granule proteins in permeabilized parasites was augmented by the non-hydrolyzable GTP analogue guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) (Chaturvedi, S., Qi, H., Coleman, D. L., Hanson, P., Rodriguez, A., and Joiner, K. A. (1998) J. Biol. Chem. 274, 2424-2431). As now demonstrated by pharmacological and electron microscopic approaches, GTPgammaS enhanced release of dense granule proteins in the permeabilized cell system. To investigate the role of ADP-ribosylation factor 1 (ARF1) in this process, a cDNA encoding T. gondii ARF1 (TgARF1) was isolated. Endogenous and transgenic TgARF1 localized to the Golgi of T. gondii, but not to dense granules. An epitope-tagged mutant of TgARF1 predicted to be impaired in GTP hydrolysis (Q71L) partially dispersed the Golgi signal, with localization to scattered vesicles, whereas a mutant impaired in nucleotide binding (T31N) was cytosolic in location. Both mutants caused partial dispersion of a Golgi/trans-Golgi network marker. TgARF1 mutants inhibited delivery of the secretory reporter, Escherichia coli alkaline phosphatase, to dense granules, precluding an in vivo assessment of the role of TgARF1 in release of intact dense granules. To circumvent this limitation, recombinant TgARF1 was purified using two separate approaches, and used in the permeabilized cell assay. TgARF1 protein purified on a Cibacron G3 column and able to bind GTP stimulated dense granule secretion in the permeabilized cell secretion assay. These results are the first to show that ARF1 can augment release of constitutively secreted vesicles at the target membrane.
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Affiliation(s)
- A Liendo
- Department of Internal Medicine, Section of Infectious Diseases, Yale University School of Medicine, New Haven, Connecticut 06520-8022, USA
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42
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Hayashi M, Taniguchi S, Ishizuka Y, Kim HS, Wataya Y, Yamamoto A, Moriyama Y. A homologue of N-ethylmaleimide-sensitive factor in the malaria parasite Plasmodium falciparum is exported and localized in vesicular structures in the cytoplasm of infected erythrocytes in the brefeldin A-sensitive pathway. J Biol Chem 2001; 276:15249-55. [PMID: 11278971 DOI: 10.1074/jbc.m011709200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-Ethylmaleimide-sensitive factor (NSF) and its homologues play a central role in vesicular trafficking in eukaryotic cells. We have identified a NSF homologue in Plasmodium falciparum (PfNSF). The reported PfNSF gene sequence (GenBank accession number CAB10575) indicated that PfNSF comprises 783 amino acids with a calculated molecular weight of 89,133. The overall identities of its gene and amino acid sequences with those of rat NSF are 50.9 and 48.8%, respectively. Reverse transcription-polymerase chain reaction analysis and Northern blotting with total P. falciparum RNA indicated expression of the PfNSF gene. Polyclonal antibodies against a conserved region of NSF specifically recognized an 89-kDa polypeptide in the parasite cells. After homogenization of the parasite cells, approximately 90% of an 89-kDa polypeptide is associated with particulate fraction, suggesting membrane-bound nature of PfNSF. PfNSF was present within both the parasite cells and the vesicular structure outside of the parasite cells. The export of PfNSF outside of the parasite cells appears to occur at the early trophozoite stage and to terminate at the merozoite stage. The export of PfNSF is inhibited by brefeldin A, with 9 microM causing 50% inhibition. Immunoelectromicroscopy indicated that intracellular PfNSF was associated with organelles such as food vacuoles and that extracellular PfNSF was associated with vesicular structures in the erythrocyte cytoplasm. These results indicate that PfNSF expressed in the malaria parasite is exported to the extracellular space and then localized in intraerythrocytic vesicles in a brefeldin A-sensitive manner. It is suggested that a vesicular transport mechanism is involved in protein export targeted to erythrocyte membranes during intraerythrocytic development of the malaria parasite.
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Affiliation(s)
- M Hayashi
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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43
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Striepen B, Soldati D, Garcia-Reguet N, Dubremetz JF, Roos DS. Targeting of soluble proteins to the rhoptries and micronemes in Toxoplasma gondii. Mol Biochem Parasitol 2001; 113:45-53. [PMID: 11254953 DOI: 10.1016/s0166-6851(00)00379-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Rhoptry and microneme organelles of the protozoan parasite Toxoplasma gondii are closely associated with host cell adhesion/invasion and establishment of the intracellular parasitophorous vacuole. In order to study the targeting of proteins to these specialized secretory organelles, we have engineered green fluorescent protein (GFP) fusions to the rhoptry protein ROP1 and the microneme protein MIC3. Both chimeras are correctly targeted to the appropriate organelles, permitting deletion analysis to map protein subdomains critical for targeting. The propeptide and a central 146 amino acid region of ROP1 are sufficient to target GFP to the rhoptries. More extensive deletions result in a loss of rhoptry targeting; the GFP reporter is diverted into the parasitophorous vacuole via dense granules. Certain MIC3 deletion mutants were also secreted into the parasitophorous vacuole via dense granules, supporting the view that this route constitutes the default pathway in T. gondii, and that specific signals are required for sorting to rhoptries and micronemes. Deletions within the cysteine-rich central region of MIC3 cause this protein to be arrested at various locations within the secretory pathway, presumably due to improper folding. Although correctly targeted to the appropriate organelles in living parasites, ROP1-GFP and MIC3-GFP fusion proteins were not secreted during invasion. GFP fusion proteins were readily secreted from dense granules, however, suggesting that protein secretion from rhoptries and micronemes might involve more than a simple release of organellar contents.
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Affiliation(s)
- B Striepen
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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44
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Ferguson DJ, Brecht S, Soldati D. The microneme protein MIC4, or an MIC4-like protein, is expressed within the macrogamete and associated with oocyst wall formation in Toxoplasma gondii. Int J Parasitol 2000; 30:1203-9. [PMID: 11027789 DOI: 10.1016/s0020-7519(00)00096-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The expression and localisation of MIC4, or an immuno-cross reacting MIC4-like protein, was examined in the enteric forms of Toxoplasma gondii using immunocytochemistry. In addition to being located within the micronemes of the merozoites, MIC4 or the MIC4-like protein was present within the macrogamete and was associated with the developing oocyst wall. The macrogamete is characterised by two types of structurally distinct wall forming bodies (WFB1 and 2). However, by immuno-electron microscopy, it was possible to identify two populations of dense granules (WFB1) which appear to form sequentially during macrogamete development. The first granules to form (WFB1a) stained positively with anti-MIC4 and were followed by MIC4 negative granules (WFB1b). During oocyst wall formation, the WFB1a and b sequentially released their contents onto the surface with WFB1a material forming an anti-MIC4 positive outer veil, while the WFB1b forms the electron dense outer layer of the oocyst wall. The inner layer was formed by WFB2. Thus, for the first time, it was possible to identify two populations of dense granules (WFB1a and b) involved in the formation of different parts of the oocyst wall. It was not possible to analyse the contents of macrogametes by western blot to unequivocally identify the antigen recognised by the polyclonal antisera as MIC4.
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Affiliation(s)
- D J Ferguson
- Nuffield Department of Pathology, Oxford University, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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45
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Kaasch AJ, Joiner KA. Protein-targeting determinants in the secretory pathway of apicomplexan parasites. Curr Opin Microbiol 2000; 3:422-8. [PMID: 10972505 DOI: 10.1016/s1369-5274(00)00115-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Apicomplexan parasites possess a highly specialized secretory apparatus. The timed secretion of proteins from three different organelles--micronemes, rhoptries and dense granules--serves to establish and maintain a parasitophorous vacuole inside the host cell in which the parasites can divide. Recent efforts have identified components that sort apicomplexan proteins to these unusual secretory organelles and have shown that this machinery is evolutionarily conserved across species. Concise amino acid sequences (e.g. tyrosine-based motifs) within the targeted protein determine their destination in Apicomplexa in a way similar to mammalian cells. Additionally, the parasite exploits new or unusual mechanisms of protein targeting (e.g. post-secretory membrane insertion).
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Affiliation(s)
- A J Kaasch
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8022, USA
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46
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Abstract
Paramecium is a unicell in which cellular processes are amenable to genetic dissection. Regulated secretion, which designates a secretory pathway where secretory products are first stored in intracellular granules and then released by exocytotic membrane fusion upon external trigger, is an important function in Paramecium, involved in defensive response through the release of organelles called trichocysts. In this review, we focus on recent advances in the molecular genetics of two major aspects of the regulated pathway in Paramecium, the biogenesis of the secretory organelles and their exocytosis.
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Affiliation(s)
- L Vayssié
- Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France
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47
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Roos DS, Crawford MJ, Donald RG, Fohl LM, Hager KM, Kissinger JC, Reynolds MG, Striepen B, Sullivan WJ. Transport and trafficking: Toxoplasma as a model for Plasmodium. NOVARTIS FOUNDATION SYMPOSIUM 2000; 226:176-95; discussion 195-8. [PMID: 10645546 DOI: 10.1002/9780470515730.ch13] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Like Plasmodium, the protozoan parasite Toxoplasma gondii is a member of the phylum Apicomplexa, and an obligate intracellular pathogen. Unlike Plasmodium, however, Toxoplasma is highly amenable to experimental manipulation in the laboratory. The development of molecular transformation protocols for T. gondii has provided both scientific precedent and practical selectable markers for Plasmodium. Beyond the feasibility of molecular biological experimentation now possible in both systems, the high frequency of stable transformation in Toxoplasma allows this parasite to be used for molecular genetic analysis. The ability to control homologous vs. non-homologous recombination in T. gondii permits gene knockouts/allelic replacements at previously cloned loci, and saturation insertional mutagenesis of the entire parasite genome (and cloning of the tagged loci). T. gondii also exhibits unusual ultrastructural clarity, facilitating cell biological analysis. The accessibility of Toxoplasma as an experimental system allows this parasite to be used as a surrogate for asking many questions that cannot easily be addressed in Plasmodium itself. T. gondii also serves as a model system for genetic exploration of parasite biology and host-parasite interactions. Success stories include: biochemical analysis of antifolate resistance mechanisms; pharmacological studies on the mechanisms of macrolide activity; genetic identification of nucleobase/nucleoside transporters and metabolic pathways; and cell biological characterization of the apicomplexan plastid. As with any model system, not all questions of interest to malariologists can be addressed in Toxoplasma; differentiating between sensible and foolish questions requires familiarity with the biological similarities and differences of these systems.
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Affiliation(s)
- D S Roos
- Department of Biology, University of Pennsylvania, Goddard Laboratories, Philadelphia 19104-6018, USA
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48
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Liendo A, Joiner KA. Toxoplasma gondii: conserved protein machinery in an unusual secretory pathway? Microbes Infect 2000; 2:137-44. [PMID: 10742686 DOI: 10.1016/s1286-4579(00)00274-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The protozoan parasite Toxoplasma gondii has a very specialized secretory apparatus. In this review we will discuss how different methodological approaches, including morphological studies, biochemistry and genetics, are revealing a novel secretory organization, whose function is performed, mainly, by a highly conserved protein machinery found in mammalian cells.
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Affiliation(s)
- A Liendo
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, LCI 808, 333 Cedar St., New Haven, CT 06520-8022, USA
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49
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Ngô HM, Hoppe HC, Joiner KA. Differential sorting and post-secretory targeting of proteins in parasitic invasion. Trends Cell Biol 2000; 10:67-72. [PMID: 10652517 DOI: 10.1016/s0962-8924(99)01698-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Toxoplasma gondii uses a highly coordinated arsenal of three structurally and biochemically distinct secretory granules to invade and develop in a wide range of host cells. Proteins of these secretory granules are sorted to strategic subcellular locations using distinctive sorting signals and are then triggered differentially for exocytosis. These secreted proteins are subsequently targeted and inserted into membrane domains.
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Affiliation(s)
- H M Ngô
- Dept of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8022, USA
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50
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Coppens I, Andries M, Liu JL, Cesbron-Delauw MF. Intracellular trafficking of dense granule proteins in Toxoplasma gondii and experimental evidences for a regulated exocytosis. Eur J Cell Biol 1999; 78:463-72. [PMID: 10472799 DOI: 10.1016/s0171-9335(99)80073-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dense granules of the intracellular protozoan Toxoplasma gondii are secretory vesicles that play a major role in the structural modifications of the parasitophorous vacuole (PV) in which the parasite develops. The biogenesis of dense granules as well as the regulatory mechanisms controlling their specific exocytosis are still poorly understood. In this paper, we analyzed the secretory pathway of dense granule proteins (GRA proteins) in extracellular T. gondii through the effects of brefeldin A (BFA). Ultrastructural studies of BFA-treated parasites showed disassembly of the Golgi apparatus and accumulation of GRA proteins in a dilated vacuolar system connected to the nuclear envelope. BFA reversibly blocked the intracellular transport of the newly synthesized GRA proteins in a dose-dependent manner (blockade of 95% at 1 microg/ml of BFA). By contrast, discharge of GRA proteins from preformed dense granules was unaffected by BFA over a course of 60 min incubation. GRA protein secretion was dependent on incubation temperature as it only occurred above 26 degrees C and it could be stimulated by external factors. This stimulus might be provided by factor(s) present in the serum of the extracellular medium, as incubation of parasites in serum-free medium resulted in a dramatic decrease in protein secretion. Exocytosis can be restored in a dose-dependent fashion by serum addition (maximal stimulatory activity in the 30-200 kDa range) and was optimal at an extracellular pH of 6.5. Altogether, these results demonstrate that GRA proteins are exported through the Golgi apparatus via the classical secretory pathway and can be experimentally discharged from storage dense granules as regulated secretory proteins in response to specific stimulation, arguing in favor of a regulated component for dense granule exocytosis in T. gondii.
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Affiliation(s)
- I Coppens
- Laboratoire des Mécanismes moléculaires de la Pathogenèse des Sporozoaires, Institut Pasteur & Institut de Biologie de Lille, France
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