101
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Aspartyl Protease 5 Matures Dense Granule Proteins That Reside at the Host-Parasite Interface in Toxoplasma gondii. mBio 2018; 9:mBio.01796-18. [PMID: 30377279 PMCID: PMC6212819 DOI: 10.1128/mbio.01796-18] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Toxoplasma gondii is one of the most successful human parasites. Central to its success is the arsenal of virulence proteins introduced into the infected host cell. Several of these virulence proteins require direct maturation by the aspartyl protease ASP5, and all require ASP5 for translocation into the host cell, yet the true number of ASP5 substrates and complete repertoire of effectors is currently unknown. Here we selectively enrich N-terminally derived peptides using Terminal Amine Isotopic Labeling of Substrates (TAILS) and use quantitative proteomics to reveal novel ASP5 substrates. We identify, using two different enrichment techniques, new ASP5 substrates and their specific cleavage sites. ASP5 substrates include two kinases and one phosphatase that reside at the host-parasite interface, which are important for infection. Toxoplasma gondii infects approximately 30% of the world’s population, causing disease primarily during pregnancy and in individuals with weakened immune systems. Toxoplasma secretes and exports effector proteins that modulate the host during infection, and several of these proteins are processed by the Golgi-associated aspartyl protease 5 (ASP5). Here, we identify ASP5 substrates by selectively enriching N-terminally derived peptides from wild-type and Δasp5 parasites. We reveal more than 2,000 unique Toxoplasma N-terminal peptides, mapping to both natural N termini and protease cleavage sites. Several of these peptides mapped directly downstream of the characterized ASP5 cleavage site, arginine-arginine-leucine (RRL). We validate candidates as true ASP5 substrates, revealing they are not processed in parasites lacking ASP5 or in wild-type parasites following mutation of the motif from RRL to ARL. All identified ASP5 substrates are dense granule proteins, and interestingly, none appear to be exported, thus differing from the analogous system in related Plasmodium spp. Instead we show that the majority of substrates reside within the parasitophorous vacuole (PV), and its membrane (the PVM), including two kinases and one phosphatase. We show that genetic deletion of WNG2 leads to attenuation in a mouse model, suggesting that this putative kinase is a new virulence factor in Toxoplasma. Collectively, these data constitute the first in-depth analyses of ASP5 substrates and shed new light on the role of ASP5 as a maturase of dense granule proteins during the Toxoplasma lytic cycle.
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102
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Kudyba HM, Cobb DW, Florentin A, Krakowiak M, Muralidharan V. CRISPR/Cas9 Gene Editing to Make Conditional Mutants of Human Malaria Parasite P. falciparum. J Vis Exp 2018. [PMID: 30295650 DOI: 10.3791/57747] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Malaria is a significant cause of morbidity and mortality worldwide. This disease, which primarily affects those living in tropical and subtropical regions, is caused by infection with Plasmodium parasites. The development of more effective drugs to combat malaria can be accelerated by improving our understanding of the biology of this complex parasite. Genetic manipulation of these parasites is key to understanding their biology; however, historically the genome of P. falciparum has been difficult to manipulate. Recently, CRISPR/Cas9 genome editing has been utilized in malaria parasites, allowing for easier protein tagging, generation of conditional protein knockdowns, and deletion of genes. CRISPR/Cas9 genome editing has proven to be a powerful tool for advancing the field of malaria research. Here, we describe a CRISPR/Cas9 method for generating glmS-based conditional knockdown mutants in P. falciparum. This method is highly adaptable to other types of genetic manipulations, including protein tagging and gene knockouts.
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Affiliation(s)
- Heather M Kudyba
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia
| | - David W Cobb
- Department of Cellular Biology, University of Georgia
| | - Anat Florentin
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia
| | | | - Vasant Muralidharan
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia;
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103
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Ho CM, Beck JR, Lai M, Cui Y, Goldberg DE, Egea PF, Zhou ZH. Malaria parasite translocon structure and mechanism of effector export. Nature 2018; 561:70-75. [PMID: 30150771 PMCID: PMC6555636 DOI: 10.1038/s41586-018-0469-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/19/2018] [Indexed: 12/18/2022]
Abstract
The putative Plasmodium translocon of exported proteins (PTEX) is essential for transport of malarial effector proteins across a parasite-encasing vacuolar membrane into host erythrocytes, but the mechanism of this process remains unknown. Here we show that PTEX is a bona fide translocon by determining structures of the PTEX core complex at near-atomic resolution using cryo-electron microscopy. We isolated the endogenous PTEX core complex containing EXP2, PTEX150 and HSP101 from Plasmodium falciparum in the 'engaged' and 'resetting' states of endogenous cargo translocation using epitope tags inserted using the CRISPR-Cas9 system. In the structures, EXP2 and PTEX150 interdigitate to form a static, funnel-shaped pseudo-seven-fold-symmetric protein-conducting channel spanning the vacuolar membrane. The spiral-shaped AAA+ HSP101 hexamer is tethered above this funnel, and undergoes pronounced compaction that allows three of six tyrosine-bearing pore loops lining the HSP101 channel to dissociate from the cargo, resetting the translocon for the next threading cycle. Our work reveals the mechanism of P. falciparum effector export, and will inform structure-based design of drugs targeting this unique translocon.
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Affiliation(s)
- Chi-Min Ho
- The Molecular Biology Institute, University of California, Los Angeles, CA, USA
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA, USA
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Josh R Beck
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
| | - Mason Lai
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA, USA
| | - Yanxiang Cui
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Daniel E Goldberg
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Pascal F Egea
- The Molecular Biology Institute, University of California, Los Angeles, CA, USA.
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
| | - Z Hong Zhou
- The Molecular Biology Institute, University of California, Los Angeles, CA, USA.
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, CA, USA.
- California NanoSystems Institute, University of California, Los Angeles, CA, USA.
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104
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Garten M, Nasamu AS, Niles JC, Zimmerberg J, Goldberg DE, Beck JR. EXP2 is a nutrient-permeable channel in the vacuolar membrane of Plasmodium and is essential for protein export via PTEX. Nat Microbiol 2018; 3:1090-1098. [PMID: 30150733 PMCID: PMC6158082 DOI: 10.1038/s41564-018-0222-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 07/23/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Garten
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Armiyaw S Nasamu
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Daniel E Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.
| | - Josh R Beck
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA.,Department of Biomedical Sciences, Iowa State University, Ames, IA, USA
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105
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Suresh N, Haldar K. Mechanisms of artemisinin resistance in Plasmodium falciparum malaria. Curr Opin Pharmacol 2018; 42:46-54. [PMID: 30077118 PMCID: PMC6314025 DOI: 10.1016/j.coph.2018.06.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/31/2018] [Accepted: 06/04/2018] [Indexed: 11/28/2022]
Abstract
Artemisinin-based combination therapies (ACTs) have substantially reduced worldwide malaria burden and deaths. But malaria parasites have become resistant to artemisinins. Prior studies suggested two different molecular pathways of artemisinin-resistance. Here we unify recent findings into a single model, where elevation of a lipid, phosphatidylinositol-3- phosphate (PI3P) results in vesicle expansion that increases the engagement with the unfolded protein response (UPR). Vesicle expansion (rather than increasing individual genetic determinants of the UPR) efficiently induces artemisinin resistance likely by promoting ‘proteostasis’ (protein translation coupled to proper protein folding and vesicular remodeling) to mitigate artemisinin-induced proteopathy (death from global abnormal protein-toxicity). Vesicular amplification engages the host red cell, suggesting that artemisinin resistant malaria may also persist by taking advantage of host niches and escaping the immune response.
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Affiliation(s)
- Niraja Suresh
- Boler-Parseghian Center for Rare and Neglected Diseases, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA; Department of Biological Sciences, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA
| | - Kasturi Haldar
- Boler-Parseghian Center for Rare and Neglected Diseases, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA; Department of Biological Sciences, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA.
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106
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Charnaud SC, Jonsdottir TK, Sanders PR, Bullen HE, Dickerman BK, Kouskousis B, Palmer CS, Pietrzak HM, Laumaea AE, Erazo AB, McHugh E, Tilley L, Crabb BS, Gilson PR. Spatial organization of protein export in malaria parasite blood stages. Traffic 2018; 19:605-623. [DOI: 10.1111/tra.12577] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 04/21/2018] [Accepted: 04/24/2018] [Indexed: 12/29/2022]
Affiliation(s)
| | - Thorey K. Jonsdottir
- Burnet Institute; Melbourne Australia
- Peter Doherty Institute for Infection and Immunity, University of Melbourne; Melbourne Australia
| | | | | | | | - Betty Kouskousis
- Burnet Institute; Melbourne Australia
- Monash Micro Imaging, Monash University; Melbourne Australia
| | - Catherine S. Palmer
- Burnet Institute; Melbourne Australia
- Monash Micro Imaging, Monash University; Melbourne Australia
| | | | | | | | - Emma McHugh
- Department of Biochemistry and Molecular Biology, University of Melbourne; Melbourne Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology, University of Melbourne; Melbourne Australia
| | - Brendan S. Crabb
- Burnet Institute; Melbourne Australia
- Peter Doherty Institute for Infection and Immunity, University of Melbourne; Melbourne Australia
- Department of Microbiology, Monash University; Melbourne Australia
| | - Paul R. Gilson
- Burnet Institute; Melbourne Australia
- Department of Microbiology, Monash University; Melbourne Australia
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107
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Kushwaha AK, Apolis L, Ito D, Desai SA. Increased Ca ++ uptake by erythrocytes infected with malaria parasites: Evidence for exported proteins and novel inhibitors. Cell Microbiol 2018; 20:e12853. [PMID: 29726084 DOI: 10.1111/cmi.12853] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/18/2018] [Accepted: 04/24/2018] [Indexed: 12/12/2022]
Abstract
Malaria parasites export many proteins into their host erythrocytes and increase membrane permeability to diverse solutes. Although most solutes use a broad-selectivity channel known as the plasmodial surface anion channel, increased Ca++ uptake is mediated by a distinct, poorly characterised mechanism that appears to be essential for the intracellular parasite. Here, we examined infected cell Ca++ uptake with a kinetic fluorescence assay and the virulent human pathogen, Plasmodium falciparum. Cell surface labelling with N-hydroxysulfosuccinimide esters revealed differing effects on transport into infected and uninfected cells, indicating that Ca++ uptake at the infected cell surface is mediated by new or altered proteins at the host membrane. Conditional knockdown of PTEX, a translocon for export of parasite proteins into the host cell, significantly reduced infected cell Ca++ permeability, suggesting involvement of parasite-encoded proteins trafficked to the host membrane. A high-throughput chemical screen identified the first Ca++ transport inhibitors active against Plasmodium-infected cells. These novel chemical scaffolds inhibit both uptake and parasite growth; improved in vitro potency at reduced free [Ca++ ] is consistent with parasite killing specifically via action on one or more Ca++ transporters. These inhibitors should provide mechanistic insights into malaria parasite Ca++ transport and may be starting points for new antimalarial drugs.
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Affiliation(s)
- Ambuj K Kushwaha
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Liana Apolis
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Daisuke Ito
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Sanjay A Desai
- The Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
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108
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CLAG3 Self-Associates in Malaria Parasites and Quantitatively Determines Nutrient Uptake Channels at the Host Membrane. mBio 2018; 9:mBio.02293-17. [PMID: 29739907 PMCID: PMC5941077 DOI: 10.1128/mbio.02293-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Malaria parasites increase host erythrocyte permeability to ions and nutrients via a broad-selectivity channel known as the plasmodial surface anion channel (PSAC), linked to parasite-encoded CLAG3 and two associated proteins. These proteins lack the multiple transmembrane domains typically present in channel-forming proteins, raising doubts about their precise roles. Using the virulent human Plasmodium falciparum parasite, we report that CLAG3 undergoes self-association and that this protein’s expression determines channel phenotype quantitatively. We overcame epigenetic silencing of clag3 paralogs and engineered parasites that express two CLAG3 isoforms simultaneously. Stoichiometric expression of these isoforms yielded intermediate channel phenotypes, in agreement with observed trafficking of both proteins to the host membrane. Coimmunoprecipitation and surface labeling revealed formation of CLAG3 oligomers. In vitro selections applied to these transfectant lines yielded distinct mutants with correlated changes in channel activity. These findings support involvement of the identified oligomers in PSAC formation and parasite nutrient acquisition. Malaria parasites are globally important pathogens that evade host immunity by replicating within circulating erythrocytes. To facilitate intracellular growth, these parasites increase erythrocyte nutrient uptake through an unusual ion channel. The parasite CLAG3 protein is a key determinant of this channel, but its lack of homology to known ion channels has raised questions about possible mechanisms. Using a new method that allows simultaneous expression of two different CLAG3 proteins, we identify self-association of CLAG3. The two expressed isoforms faithfully traffic to and insert in the host membrane, while remaining associated with two unrelated parasite proteins. Both the channel phenotypes and molecular changes produced upon selections with a highly specific channel inhibitor are consistent with a multiprotein complex that forms the nutrient pore. These studies support direct involvement of the CLAG3 protein in channel formation and are relevant to antimalarial drug discovery projects targeting parasite nutrient acquisition.
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109
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Chisholm SA, Kalanon M, Nebl T, Sanders PR, Matthews KM, Dickerman BK, Gilson PR, de Koning-Ward TF. The malaria PTEX component PTEX88 interacts most closely with HSP101 at the host-parasite interface. FEBS J 2018; 285:2037-2055. [PMID: 29637707 DOI: 10.1111/febs.14463] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 03/08/2018] [Accepted: 04/03/2018] [Indexed: 12/28/2022]
Abstract
The pathogenic nature of malaria infections is due in part to the export of hundreds of effector proteins that actively remodel the host erythrocyte. The Plasmodium translocon of exported proteins (PTEX) has been shown to facilitate the trafficking of proteins into the host cell, a process that is essential for the survival of the parasite. The role of the auxiliary PTEX component PTEX88 remains unclear, as previous attempts to elucidate its function through reverse genetic approaches showed that in contrast to the core components PTEX150 and HSP101, knockdown of PTEX88 did not give rise to an export phenotype. Here, we have used biochemical approaches to understand how PTEX88 assembles within the translocation machinery. Proteomic analysis of the PTEX88 interactome showed that PTEX88 interacts closely with HSP101 but has a weaker affinity with the other core constituents of PTEX. PTEX88 was also found to associate with other PV-resident proteins, including chaperones and members of the exported protein-interacting complex that interacts with the major virulence factor PfEMP1, the latter contributing to cytoadherence and parasite virulence. Despite being expressed for the duration of the blood-stage life cycle, PTEX88 was only discretely observed at the parasitophorous vacuole membrane during ring stages and could not always be detected in the major high molecular weight complex that contains the other core components of PTEX, suggesting that its interaction with the PTEX complex may be dynamic. Together, these data have enabled the generation of an updated model of PTEX that now includes how PTEX88 assembles within the complex.
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Affiliation(s)
| | - Ming Kalanon
- School of Medicine, Deakin University, Waurn Ponds, Australia
| | - Thomas Nebl
- The Walter and Eliza Hall Institute, Parkville, Australia
| | - Paul R Sanders
- Burnet Institute, Prahran, Australia.,Monash University, Melbourne, Australia
| | | | | | - Paul R Gilson
- Burnet Institute, Prahran, Australia.,Monash University, Melbourne, Australia
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110
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Naor A, Panas MW, Marino N, Coffey MJ, Tonkin CJ, Boothroyd JC. MYR1-Dependent Effectors Are the Major Drivers of a Host Cell's Early Response to Toxoplasma, Including Counteracting MYR1-Independent Effects. mBio 2018; 9:e02401-17. [PMID: 29615509 PMCID: PMC5885026 DOI: 10.1128/mbio.02401-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/07/2018] [Indexed: 01/08/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii controls its host cell from within the parasitophorous vacuole (PV) by using a number of diverse effector proteins, a subset of which require the aspartyl protease 5 enzyme (ASP5) and/or the recently discovered MYR1 protein to cross the PV membrane. To examine the impact these effectors have in the context of the entirety of the host response to Toxoplasma, we used RNA-Seq to analyze the transcriptome expression profiles of human foreskin fibroblasts infected with wild-type RH (RH-WT), RHΔmyr1, and RHΔasp5 tachyzoites. Interestingly, the majority of the differentially regulated genes responding to Toxoplasma infection are MYR1 dependent. A subset of MYR1 responses were ASP5 independent, and MYR1 function did not require ASP5 cleavage, suggesting the export of some effectors requires only MYR1. Gene set enrichment analysis of MYR1-dependent host responses suggests an upregulation of E2F transcription factors and the cell cycle and a downregulation related to interferon signaling, among numerous others. Most surprisingly, "hidden" responses arising in RHΔmyr1- but not RH-WT-infected host cells indicate counterbalancing actions of MYR1-dependent and -independent activities. The host genes and gene sets revealed here to be MYR1 dependent provide new insight into the parasite's ability to co-opt host cell functions.IMPORTANCEToxoplasma gondii is unique in its ability to successfully invade and replicate in a broad range of host species and cells within those hosts. The complex interplay of effector proteins exported by Toxoplasma is key to its success in co-opting the host cell to create a favorable replicative niche. Here we show that a majority of the transcriptomic effects in tachyzoite-infected cells depend on the activity of a novel translocation system involving MYR1 and that the effectors delivered by this system are part of an intricate interplay of activators and suppressors. Removal of all MYR1-dependent effectors reveals previously unknown activities that are masked or hidden by the action of these proteins.
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Affiliation(s)
- Adit Naor
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Michael W Panas
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Nicole Marino
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Michael J Coffey
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - Christopher J Tonkin
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, Australia
| | - John C Boothroyd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
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111
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Morita M, Nagaoka H, Ntege EH, Kanoi BN, Ito D, Nakata T, Lee JW, Tokunaga K, Iimura T, Torii M, Tsuboi T, Takashima E. PV1, a novel Plasmodium falciparum merozoite dense granule protein, interacts with exported protein in infected erythrocytes. Sci Rep 2018; 8:3696. [PMID: 29487358 PMCID: PMC5829233 DOI: 10.1038/s41598-018-22026-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 02/07/2018] [Indexed: 01/09/2023] Open
Abstract
Upon invasion, Plasmodium falciparum exports hundreds of proteins across its surrounding parasitophorous vacuole membrane (PVM) to remodel the infected erythrocyte. Although this phenomenon is crucial for the parasite growth and virulence, elucidation of precise steps in the export pathway is still required. A translocon protein complex, PTEX, is the only known pathway that mediates passage of exported proteins across the PVM. P. falciparum Parasitophorous Vacuolar protein 1 (PfPV1), a previously reported parasitophorous vacuole (PV) protein, is considered essential for parasite growth. In this study, we characterized PfPV1 as a novel merozoite dense granule protein. Structured illumination microscopy (SIM) analyses demonstrated that PfPV1 partially co-localized with EXP2, suggesting the protein could be a PTEX accessory molecule. Furthermore, PfPV1 and exported protein PTP5 co-immunoprecipitated with anti-PfPV1 antibody. Surface plasmon resonance (SPR) confirmed the proteins’ direct interaction. Additionally, we identified a PfPV1 High-affinity Region (PHR) at the C-terminal side of PTP5 where PfPV1 dominantly bound. SIM analysis demonstrated an export arrest of PTP5ΔPHR, a PTP5 mutant lacking PHR, suggesting PHR is essential for PTP5 export to the infected erythrocyte cytosol. The overall results suggest that PfPV1, a novel dense granule protein, plays an important role in protein export at PV.
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Affiliation(s)
- Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Edward H Ntege
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Bernard N Kanoi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Daisuke Ito
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.,Division of Medical Zoology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Yonago, Tottori, 683-8503, Japan
| | - Takahiro Nakata
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Ji-Won Lee
- Division of Bio-Imaging, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime, Japan
| | | | - Tadahiro Iimura
- Division of Bio-Imaging, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime, Japan.,Division of Analytical Bio-Medicine, Advanced Research Support Center, Ehime University, Shitsukawa, Toon, Ehime, Japan
| | - Motomi Torii
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.
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112
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Wang P, Li J, Sha B. Preliminary X-Ray Crystallographic Studies of the N-Terminal Domains of Hsp104 from Yeast Candida albicans and Saccharomyces cerevisiae. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s1063774517070331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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113
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Remodeling of the malaria parasite and host human red cell by vesicle amplification that induces artemisinin resistance. Blood 2018; 131:1234-1247. [PMID: 29363540 DOI: 10.1182/blood-2017-11-814665] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/12/2018] [Indexed: 12/25/2022] Open
Abstract
Artemisinin resistance threatens worldwide malaria control and elimination. Elevation of phosphatidylinositol-3-phosphate (PI3P) can induce resistance in blood stages of Plasmodium falciparum The parasite unfolded protein response (UPR) has also been implicated as a proteostatic mechanism that may diminish artemisinin-induced toxic proteopathy. How PI3P acts and its connection to the UPR remain unknown, although both are conferred by mutation in P falciparum Kelch13 (K13), the marker of artemisinin resistance. Here we used cryoimmunoelectron microscopy to show that K13 concentrates at PI3P tubules/vesicles of the parasite's endoplasmic reticulum (ER) in infected red cells. K13 colocalizes and copurifies with the major virulence adhesin PfEMP1. The PfEMP1-K13 proteome is comprehensively enriched in multiple proteostasis systems of protein export, quality control, and folding in the ER and cytoplasm and UPR. Synthetic elevation of PI3P that induces resistance in absence of K13 mutation also yields signatures of proteostasis and clinical resistance. These findings imply a key role for PI3P-vesicle amplification as a mechanism of resistance of infected red cells. As validation, the major resistance mutation K13C580Y quantitatively increased PI3P tubules/vesicles, exporting them throughout the parasite and the red cell. Chemical inhibitors and fluorescence microscopy showed that alterations in PfEMP1 export to the red cell and cytoadherence of infected cells to a host endothelial receptor are features of multiple K13 mutants. Together these data suggest that amplified PI3P vesicles disseminate widespread proteostatic capacity that may neutralize artemisinins toxic proteopathy and implicate a role for the host red cell in artemisinin resistance. The mechanistic insights generated will have an impact on malaria drug development.
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114
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Marino ND, Panas MW, Franco M, Theisen TC, Naor A, Rastogi S, Buchholz KR, Lorenzi HA, Boothroyd JC. Identification of a novel protein complex essential for effector translocation across the parasitophorous vacuole membrane of Toxoplasma gondii. PLoS Pathog 2018; 14:e1006828. [PMID: 29357375 PMCID: PMC5794187 DOI: 10.1371/journal.ppat.1006828] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 02/01/2018] [Accepted: 12/18/2017] [Indexed: 01/08/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that can infect virtually all nucleated cells in warm-blooded animals. The ability of Toxoplasma tachyzoites to infect and successfully manipulate its host is dependent on its ability to transport "GRA" proteins that originate in unique secretory organelles called dense granules into the host cell in which they reside. GRAs have diverse roles in Toxoplasma's intracellular lifecycle, including co-opting crucial host cell functions and proteins, such as the cell cycle, c-Myc and p38 MAP kinase. Some of these GRA proteins, such as GRA16 and GRA24, are secreted into the parasitophorous vacuole (PV) within which Toxoplasma replicates and are transported across the PV membrane (PVM) into the host cell, but the translocation process and its machinery are not well understood. We previously showed that TgMYR1, which is cleaved by TgASP5 into two fragments, localizes to the PVM and is essential for GRA transport into the host cell. To identify additional proteins necessary for effector transport, we screened Toxoplasma mutants defective in c-Myc up-regulation for their ability to export GRA16 and GRA24 to the host cell nucleus. Here we report that novel proteins MYR2 and MYR3 play a crucial role in translocation of a subset of GRAs into the host cell. MYR2 and MYR3 are secreted into the PV space and co-localize with PV membranes and MYR1. Consistent with their predicted transmembrane domains, all three proteins are membrane-associated, and MYR3, but not MYR2, stably associates with MYR1, whose N- and C-terminal fragments are disulfide-linked. We further show that fusing intrinsically disordered effectors to a structured DHFR domain blocks the transport of other effectors, consistent with a translocon-based model of effector transport. Overall, these results reveal a novel complex at the PVM that is essential for effector translocation into the host cell.
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Affiliation(s)
- Nicole D. Marino
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Michael W. Panas
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Magdalena Franco
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Terence C. Theisen
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Adit Naor
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Suchita Rastogi
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Kerry R. Buchholz
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Hernan A. Lorenzi
- Department of Infectious Diseases, J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - John C. Boothroyd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
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115
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Sherling ES, van Ooij C. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes. FEMS Microbiol Rev 2017; 40:701-21. [PMID: 27587718 PMCID: PMC5007283 DOI: 10.1093/femsre/fuw016] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2016] [Indexed: 12/22/2022] Open
Abstract
Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. Plasmodium parasites remodel the host erythrocyte in various ways, including the formation of several membranous compartments, together referred to as the exomembrane system, within the erythrocyte cytosol that together are key to the sweeping changes in the host cell.
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Affiliation(s)
- Emma S Sherling
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Christiaan van Ooij
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
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116
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Abdi A, Yu L, Goulding D, Rono MK, Bejon P, Choudhary J, Rayner J. Proteomic analysis of extracellular vesicles from a Plasmodium falciparum Kenyan clinical isolate defines a core parasite secretome. Wellcome Open Res 2017; 2:50. [PMID: 28944300 PMCID: PMC5583745 DOI: 10.12688/wellcomeopenres.11910.2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Many pathogens secrete effector molecules to subvert host immune responses, to acquire nutrients, and/or to prepare host cells for invasion. One of the ways that effector molecules are secreted is through extracellular vesicles (EVs) such as exosomes. Recently, the malaria parasite P. falciparum has been shown to produce EVs that can mediate transfer of genetic material between parasites and induce sexual commitment. Characterizing the content of these vesicles may improve our understanding of P. falciparum pathogenesis and virulence. METHODS Previous studies of P. falciparum EVs have been limited to long-term adapted laboratory isolates. In this study, we isolated EVs from a Kenyan P. falciparum clinical isolate adapted to in vitro culture for a short period and characterized their protein content by mass spectrometry (data are available via ProteomeXchange, with identifier PXD006925). RESULTS We show that P. falciparum extracellular vesicles ( PfEVs) are enriched in proteins found within the exomembrane compartments of infected erythrocytes such as Maurer's clefts (MCs), as well as the secretory endomembrane compartments in the apical end of the merozoites, suggesting that these proteins play a role in parasite-host interactions. Comparison of this novel clinically relevant dataset with previously published datasets helps to define a core secretome present in Plasmodium EVs. CONCLUSIONS P. falciparum extracellular vesicles contain virulence-associated parasite proteins. Therefore, analysis of PfEVs contents from a range of clinical isolates, and their functional validation may improve our understanding of the virulence mechanisms of the parasite, and potentially identify targets for interventions or diagnostics.
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Affiliation(s)
- Abdirahman Abdi
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lu Yu
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - David Goulding
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Martin K Rono
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Julian Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
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117
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Abdi A, Yu L, Goulding D, Rono MK, Bejon P, Choudhary J, Rayner J. Proteomic analysis of extracellular vesicles from a Plasmodium falciparum Kenyan clinical isolate defines a core parasite secretome. Wellcome Open Res 2017. [PMID: 28944300 DOI: 10.12688/wellcomeopenres.11910.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Many pathogens secrete effector molecules to subvert host immune responses, to acquire nutrients, and/or to prepare host cells for invasion. One of the ways that effector molecules are secreted is through extracellular vesicles (EVs) such as exosomes. Recently, the malaria parasite P. falciparum has been shown to produce EVs that can mediate transfer of genetic material between parasites and induce sexual commitment. Characterizing the content of these vesicles may improve our understanding of P. falciparum pathogenesis and virulence. METHODS Previous studies of P. falciparum EVs have been limited to long-term adapted laboratory isolates. In this study, we isolated EVs from a Kenyan P. falciparum clinical isolate adapted to in vitro culture for a short period and characterized their protein content by mass spectrometry (data are available via ProteomeXchange, with identifier PXD006925). RESULTS We show that P. falciparum extracellular vesicles ( PfEVs) are enriched in proteins found within the exomembrane compartments of infected erythrocytes such as Maurer's clefts (MCs), as well as the secretory endomembrane compartments in the apical end of the merozoites, suggesting that these proteins play a role in parasite-host interactions. Comparison of this novel clinically relevant dataset with previously published datasets helps to define a core secretome present in Plasmodium EVs. CONCLUSIONS P. falciparum extracellular vesicles contain virulence-associated parasite proteins. Therefore, analysis of PfEVs contents from a range of clinical isolates, and their functional validation may improve our understanding of the virulence mechanisms of the parasite, and potentially identify targets for interventions or diagnostics.
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Affiliation(s)
- Abdirahman Abdi
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lu Yu
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - David Goulding
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Martin K Rono
- Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Julian Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
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Florentin A, Cobb DW, Fishburn JD, Cipriano MJ, Kim PS, Fierro MA, Striepen B, Muralidharan V. PfClpC Is an Essential Clp Chaperone Required for Plastid Integrity and Clp Protease Stability in Plasmodium falciparum. Cell Rep 2017; 21:1746-1756. [PMID: 29141210 PMCID: PMC5726808 DOI: 10.1016/j.celrep.2017.10.081] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/17/2017] [Accepted: 10/21/2017] [Indexed: 01/11/2023] Open
Abstract
The deadly malaria parasite Plasmodium falciparum contains a nonphotosynthetic plastid, known as the apicoplast, that functions to produce essential metabolites, and drugs that target the apicoplast are clinically effective. Several prokaryotic caseinolytic protease (Clp) genes have been identified in the Plasmodium genome. Using phylogenetic analysis, we focused on the Clp members that may form a regulated proteolytic complex in the apicoplast. We genetically targeted members of this complex and generated conditional mutants of the apicoplast-localized PfClpC chaperone and PfClpP protease. Conditional inhibition of the PfClpC chaperone resulted in growth arrest and apicoplast loss and was rescued by addition of the essential apicoplast-derived metabolite IPP. Using a double-conditional mutant parasite line, we discovered that the chaperone activity is required to stabilize the mature protease, revealing functional interactions. These data demonstrate the essential function of PfClpC in maintaining apicoplast integrity and its role in regulating the proteolytic activity of the Clp complex.
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Affiliation(s)
- Anat Florentin
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - David W Cobb
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Jillian D Fishburn
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Michael J Cipriano
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Paul S Kim
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Manuel A Fierro
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Boris Striepen
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Vasant Muralidharan
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
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119
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Ortega C, Frando A, Webb-Robertson BJ, Anderson LN, Fleck N, Flannery EL, Fishbaugher M, Murphree TA, Hansen JR, Smith RD, Kappe SHI, Wright AT, Grundner C. A Global Survey of ATPase Activity in Plasmodium falciparum Asexual Blood Stages and Gametocytes. Mol Cell Proteomics 2017; 17:111-120. [PMID: 29079720 DOI: 10.1074/mcp.ra117.000088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 10/03/2017] [Indexed: 01/12/2023] Open
Abstract
Effective malaria control and elimination in hyperendemic areas of the world will require treatment of the Plasmodium falciparum (Pf) blood stage that causes disease as well as the gametocyte stage that is required for transmission from humans to the mosquito vector. Most currently used therapies do not kill gametocytes, a highly specialized, non-replicating sexual parasite stage. Further confounding next generation drug development against Pf is the unknown metabolic state of the gametocyte and the lack of known biochemical activity for most parasite gene products in general. Here, we take a systematic activity-based proteomics approach to survey the activity of the large and druggable ATPase family in replicating blood stage asexual parasites and transmissible, non-replicating sexual gametocytes. ATPase activity broadly changes during the transition from asexual schizonts to sexual gametocytes, indicating altered metabolism and regulatory roles of ATPases specific for each lifecycle stage. We further experimentally confirm existing annotation and predict ATPase function for 38 uncharacterized proteins. By mapping the activity of ATPases associated with gametocytogenesis, we assign biochemical activity to a large number of uncharacterized proteins and identify new candidate transmission blocking targets.
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Affiliation(s)
- Corrie Ortega
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109
| | - Andrew Frando
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109.,§Department of Global Health, University of Washington, Seattle, Washington 98195
| | - Bobbie-Jo Webb-Robertson
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Lindsey N Anderson
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Neil Fleck
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109
| | - Erika L Flannery
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109
| | - Matthew Fishbaugher
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109
| | - Taylor A Murphree
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Joshua R Hansen
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Richard D Smith
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Stefan H I Kappe
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109.,§Department of Global Health, University of Washington, Seattle, Washington 98195
| | - Aaron T Wright
- ¶Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Christoph Grundner
- From the ‡Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109; .,§Department of Global Health, University of Washington, Seattle, Washington 98195
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120
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The Exported Chaperone PfHsp70x Is Dispensable for the Plasmodium falciparum Intraerythrocytic Life Cycle. mSphere 2017; 2:mSphere00363-17. [PMID: 28959740 PMCID: PMC5615134 DOI: 10.1128/msphere.00363-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/07/2017] [Indexed: 11/24/2022] Open
Abstract
Half of the world’s population lives at risk for malaria. The intraerythrocytic life cycle of Plasmodium spp. is responsible for clinical manifestations of malaria; therefore, knowledge of the parasite’s ability to survive within the erythrocyte is needed to combat the deadliest agent of malaria, P. falciparum. An outstanding question in the field is how P. falciparum undertakes the essential process of trafficking its proteins within the host cell. In most organisms, chaperones such as Hsp70 are employed in protein trafficking. Of the Plasmodium species causing human disease, the chaperone PfHsp70x is unique to P. falciparum, and it is the only parasite protein of its kind exported to the host (S. Külzer et al., Cell Microbiol 14:1784–1795, 2012). This has placed PfHsp70x as an ideal target to inhibit protein trafficking and kill the parasite. However, we show that PfHsp70x is not required for export of parasite effectors and it is not essential for parasite survival inside the RBC. Export of parasite proteins into the host erythrocyte is essential for survival of Plasmodium falciparum during its asexual life cycle. While several studies described key factors within the parasite that are involved in protein export, the mechanisms employed to traffic exported proteins within the host cell are currently unknown. Members of the Hsp70 family of chaperones, together with their Hsp40 cochaperones, facilitate protein trafficking in other organisms, and are thus likely used by P. falciparum in the trafficking of its exported proteins. A large group of Hsp40 proteins is encoded by the parasite and exported to the host cell, but only one Hsp70, P. falciparum Hsp70x (PfHsp70x), is exported with them. PfHsp70x is absent in most Plasmodium species and is found only in P. falciparum and closely related species that infect apes. Herein, we have utilized clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 genome editing in P. falciparum to investigate the essentiality of PfHsp70x. We show that parasitic growth was unaffected by knockdown of PfHsp70x using both the dihydrofolate reductase (DHFR)-based destabilization domain and the glmS ribozyme system. Similarly, a complete gene knockout of PfHsp70x did not affect the ability of P. falciparum to proceed through its intraerythrocytic life cycle. The effect of PfHsp70x knockdown/knockout on the export of proteins to the host red blood cell (RBC), including the critical virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), was tested, and we found that this process was unaffected. These data show that although PfHsp70x is the sole exported Hsp70, it is not essential for the asexual development of P. falciparum. IMPORTANCE Half of the world’s population lives at risk for malaria. The intraerythrocytic life cycle of Plasmodium spp. is responsible for clinical manifestations of malaria; therefore, knowledge of the parasite’s ability to survive within the erythrocyte is needed to combat the deadliest agent of malaria, P. falciparum. An outstanding question in the field is how P. falciparum undertakes the essential process of trafficking its proteins within the host cell. In most organisms, chaperones such as Hsp70 are employed in protein trafficking. Of the Plasmodium species causing human disease, the chaperone PfHsp70x is unique to P. falciparum, and it is the only parasite protein of its kind exported to the host (S. Külzer et al., Cell Microbiol 14:1784–1795, 2012). This has placed PfHsp70x as an ideal target to inhibit protein trafficking and kill the parasite. However, we show that PfHsp70x is not required for export of parasite effectors and it is not essential for parasite survival inside the RBC.
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121
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Cao S, Du N, Chen H, Pang Y, Zhang Z, Zheng J, Jia H. Toxoplasma gondii Clp family protein: TgClpB1 plays a crucial role in thermotolerance. Oncotarget 2017; 8:86117-86129. [PMID: 29156781 PMCID: PMC5689671 DOI: 10.18632/oncotarget.20989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 08/27/2017] [Indexed: 01/27/2023] Open
Abstract
Caseinolytic peptidase B (ClpB) plays a pivotal role in suppressing and reversing protein aggregation. Toxoplasma gondii is an intracellular parasitic protozoan that infects a wide variety of mammals and birds and therefore is exposed to a broad range of living condition. We screened ToxoDB (http://ToxoDB.org) and identified 10 putative T. gondii genes encoding members of the Clp superfamily of caseinolytic proteases and chaperones. Of these, we focused on characterizing the Class I ATP-dependent molecular chaperones TgClpB1, TgClpB2, and TgClpB3. We found that TgClpB1, the most divergent of the five T. gondii Class I Clp ATPases, is cytoplasmic, TgClpB2 is found in the mitochondria of the parasites, and TgClpB3 is a ClpB with novel apicoplast localization. Knockout strains of TgClpB1 and TgClpB2 were established by CRISPR/Cas9 mutagenesis, and their complementing strains were constructed with FLAG-tag. Although knockout of TgClpB1 or TgClpB2 did not affect growth under normal circumstances, TgClpB1 was required for T. gondii thermotolerance. The growth, replication, and invasion capabilities of TgClpB1-deficient mutants were significantly inhibited after extracellular parasites were pretreated at 45°C. Moreover, TgClpB1 were observed at the poles of the ΔTgClpB1 FLAG-tagged strain treated at 42°C.
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Affiliation(s)
- Shinuo Cao
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Nali Du
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Heming Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yu Pang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhaoxia Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Jun Zheng
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Honglin Jia
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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122
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Nyboer B, Heiss K, Mueller AK, Ingmundson A. The Plasmodium liver-stage parasitophorous vacuole: A front-line of communication between parasite and host. Int J Med Microbiol 2017; 308:107-117. [PMID: 28964681 DOI: 10.1016/j.ijmm.2017.09.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/19/2017] [Accepted: 09/11/2017] [Indexed: 12/13/2022] Open
Abstract
The intracellular development and differentiation of the Plasmodium parasite in the host liver is a prerequisite for the actual onset of malaria disease pathology. Since liver-stage infection is clinically silent and can be completely eliminated by sterilizing immune responses, it is a promising target for urgently needed innovative antimalarial drugs and/or vaccines. Discovered more than 65 years ago, these stages remain poorly understood regarding their molecular repertoire and interaction with their host cells in comparison to the pathogenic erythrocytic stages. The differentiating and replicative intrahepatic parasite resides in a membranous compartment called the parasitophorous vacuole, separating it from the host-cell cytoplasm. Here we outline seminal work that contributed to our present understanding of the fundamental dynamic cellular processes of the intrahepatic malarial parasite with both specific host-cell factors and compartments.
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Affiliation(s)
- Britta Nyboer
- Centre for Infectious Diseases, Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Kirsten Heiss
- Centre for Infectious Diseases, Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany; Centre for Infection Research (DZIF), D 69120 Heidelberg, Germany
| | - Ann-Kristin Mueller
- Centre for Infectious Diseases, Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany; Centre for Infection Research (DZIF), D 69120 Heidelberg, Germany,.
| | - Alyssa Ingmundson
- Department of Molecular Parasitology, Institute of Biology, Humboldt University Berlin, Philippstrasse 13, 10115 Berlin, Germany.
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123
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Khosh-Naucke M, Becker J, Mesén-Ramírez P, Kiani P, Birnbaum J, Fröhlke U, Jonscher E, Schlüter H, Spielmann T. Identification of novel parasitophorous vacuole proteins in P. falciparum parasites using BioID. Int J Med Microbiol 2017; 308:13-24. [PMID: 28784333 DOI: 10.1016/j.ijmm.2017.07.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 10/19/2022] Open
Abstract
Malaria blood stage parasites develop within red blood cells where they are contained in a vacuolar compartment known as the parasitophorous vacuole (PV). This compartment holds a key role in the interaction of the parasite with its host cell. However, the proteome of this compartment has so far not been comprehensively analysed. Here we used BioID in asexual blood stages of the most virulent human malaria parasite Plasmodium falciparum to identify new proteins of the PV. The resulting proteome contained many of the already known PV proteins and validation by GFP-knock-in of 10 previously in P. falciparum uncharacterised hits revealed 5 new PV proteins and two with a partial PV localisation. This included proteins peripherally attached to the inner face of the PV membrane as well as proteins anchored in the parasite plasma membrane that protrude into the PV. Using selectable targeted gene disruption we generated mutants for 2 of the 10 candidates. In contrast we could not select parasites with disruptions for another 3 candidates, strongly suggesting that they are important for parasite growth. Interestingly, one of these included the orthologue of UIS2, a protein previously proposed to regulate protein translation in the parasite cytoplasm but here shown to be an essential PV protein. This work extends the number of known PV proteins and provides a starting point for further functional analyses of this compartment.
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Affiliation(s)
- Melissa Khosh-Naucke
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Johanna Becker
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Paolo Mesén-Ramírez
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Parnian Kiani
- Core Facility Mass Spectrometric Proteomics, Institute of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Jakob Birnbaum
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Ulrike Fröhlke
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Ernst Jonscher
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany
| | - Hartmut Schlüter
- Core Facility Mass Spectrometric Proteomics, Institute of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Tobias Spielmann
- Bernhard Nocht Institute for Tropical Medicine, Parasitology Section, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany.
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Charnaud SC, Dixon MWA, Nie CQ, Chappell L, Sanders PR, Nebl T, Hanssen E, Berriman M, Chan JA, Blanch AJ, Beeson JG, Rayner JC, Przyborski JM, Tilley L, Crabb BS, Gilson PR. The exported chaperone Hsp70-x supports virulence functions for Plasmodium falciparum blood stage parasites. PLoS One 2017; 12:e0181656. [PMID: 28732045 PMCID: PMC5521827 DOI: 10.1371/journal.pone.0181656] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/05/2017] [Indexed: 12/03/2022] Open
Abstract
Malaria is caused by five different Plasmodium spp. in humans each of which modifies the host erythrocyte to survive and replicate. The two main causes of malaria, P. falciparum and P. vivax, differ in their ability to cause severe disease, mainly due to differences in the cytoadhesion of infected erythrocytes (IE) in the microvasculature. Cytoadhesion of P. falciparum in the brain leads to a large number of deaths each year and is a consequence of exported parasite proteins, some of which modify the erythrocyte cytoskeleton while others such as PfEMP1 project onto the erythrocyte surface where they bind to endothelial cells. Here we investigate the effects of knocking out an exported Hsp70-type chaperone termed Hsp70-x that is present in P. falciparum but not P. vivax. Although the growth of Δhsp70-x parasites was unaffected, the export of PfEMP1 cytoadherence proteins was delayed and Δhsp70-x IE had reduced adhesion. The Δhsp70-x IE were also more rigid than wild-type controls indicating changes in the way the parasites modified their host erythrocyte. To investigate the cause of this, transcriptional and translational changes in exported and chaperone proteins were monitored and some changes were observed. We propose that PfHsp70-x is not essential for survival in vitro, but may be required for the efficient export and functioning of some P. falciparum exported proteins.
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Affiliation(s)
| | - Matthew W. A. Dixon
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | | | - Lia Chappell
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | | | - Thomas Nebl
- Walter & Eliza Hall Institute, Melbourne, Victoria, Australia
| | - Eric Hanssen
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Jo-Anne Chan
- Burnet Institute, Melbourne, Victoria, Australia
| | - Adam J. Blanch
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | | | - Julian C. Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | | | - Leann Tilley
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Brendan S. Crabb
- Burnet Institute, Melbourne, Victoria, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria, Australia
- Monash University, Melbourne, Victoria, Australia
| | - Paul R. Gilson
- Burnet Institute, Melbourne, Victoria, Australia
- Monash University, Melbourne, Victoria, Australia
- * E-mail:
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125
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Batinovic S, McHugh E, Chisholm SA, Matthews K, Liu B, Dumont L, Charnaud SC, Schneider MP, Gilson PR, de Koning-Ward TF, Dixon MWA, Tilley L. An exported protein-interacting complex involved in the trafficking of virulence determinants in Plasmodium-infected erythrocytes. Nat Commun 2017; 8:16044. [PMID: 28691708 PMCID: PMC5508133 DOI: 10.1038/ncomms16044] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 05/20/2017] [Indexed: 01/01/2023] Open
Abstract
The malaria parasite, Plasmodium falciparum, displays the P. falciparum erythrocyte membrane protein 1 (PfEMP1) on the surface of infected red blood cells (RBCs). We here examine the physical organization of PfEMP1 trafficking intermediates in infected RBCs and determine interacting partners using an epitope-tagged minimal construct (PfEMP1B). We show that parasitophorous vacuole (PV)-located PfEMP1B interacts with components of the PTEX (Plasmodium Translocon of EXported proteins) as well as a novel protein complex, EPIC (Exported Protein-Interacting Complex). Within the RBC cytoplasm PfEMP1B interacts with components of the Maurer’s clefts and the RBC chaperonin complex. We define the EPIC interactome and, using an inducible knockdown approach, show that depletion of one of its components, the parasitophorous vacuolar protein-1 (PV1), results in altered knob morphology, reduced cell rigidity and decreased binding to CD36. Accordingly, we show that deletion of the Plasmodium berghei homologue of PV1 is associated with attenuation of parasite virulence in vivo. Plasmodium-infected red blood cells export virulence factors, such as PfEMP1, to the cell surface. Here, the authors identify a protein complex termed EPIC that interacts with PfEMP1 during export, and they show that knockdown of an EPIC component affects parasite virulence.
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Affiliation(s)
- Steven Batinovic
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Emma McHugh
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Scott A Chisholm
- School of Medicine, Deakin University, Waurn Ponds, Victoria 3220, Australia
| | - Kathryn Matthews
- School of Medicine, Deakin University, Waurn Ponds, Victoria 3220, Australia
| | - Boiyin Liu
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Laure Dumont
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Sarah C Charnaud
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria 3004, Australia
| | - Molly Parkyn Schneider
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Paul R Gilson
- Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria 3004, Australia
| | | | - Matthew W A Dixon
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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126
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Kuczynska-Wisnik D, Cheng C, Ganta RR, Zolkiewski M. Protein aggregation in Ehrlichia chaffeensis during infection of mammalian cells. FEMS Microbiol Lett 2017; 364:3071827. [PMID: 28333306 PMCID: PMC5399918 DOI: 10.1093/femsle/fnx059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/11/2017] [Indexed: 12/21/2022] Open
Abstract
Ehrlichia chaffeensis is an obligatory intracellular pathogen transmitted through infected ticks to humans and other vertebrates. We investigated the extent of protein aggregation in E. chaffeensis during infection of canine macrophage cell line, DH82. We discovered that the size of the aggregated fraction of E. chaffeensis proteins increased during the first 48 h post infection. We also incubated the infected cells with guanidinium chloride (GuHCl), a known inhibitor of the protein-disaggregating molecular chaperone ClpB. Up to 0.5 mM GuHCl had no impact on the host cells, whereas the viability of the pathogen was reduced by ∼60% in the presence of the inhibitor. Furthermore, we found that the size of the aggregated protein fraction in E. chaffeensis increased significantly in cultures supplemented with 0.5 mM GuHCl, which also resulted in the preferential accumulation of ClpB with the aggregated proteins. Altogether, our results suggest that an exposure of E. chaffeensis to the stressful environment of a host cell results in an increased aggregation of the pathogen's proteins, which is exacerbated upon inhibition of ClpB. Our studies establish a link between protein quality control and pathogen survival during infection of a host.
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Affiliation(s)
- Dorota Kuczynska-Wisnik
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA.,Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA
| | - Chuanmin Cheng
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA
| | - Roman R Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA
| | - Michal Zolkiewski
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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127
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Sherling ES, Knuepfer E, Brzostowski JA, Miller LH, Blackman MJ, van Ooij C. The Plasmodium falciparum rhoptry protein RhopH3 plays essential roles in host cell invasion and nutrient uptake. eLife 2017; 6. [PMID: 28252384 PMCID: PMC5365315 DOI: 10.7554/elife.23239] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/26/2017] [Indexed: 11/18/2022] Open
Abstract
Merozoites of the protozoan parasite responsible for the most virulent form of malaria, Plasmodium falciparum, invade erythrocytes. Invasion involves discharge of rhoptries, specialized secretory organelles. Once intracellular, parasites induce increased nutrient uptake by generating new permeability pathways (NPP) including a Plasmodium surface anion channel (PSAC). RhopH1/Clag3, one member of the three-protein RhopH complex, is important for PSAC/NPP activity. However, the roles of the other members of the RhopH complex in PSAC/NPP establishment are unknown and it is unclear whether any of the RhopH proteins play a role in invasion. Here we demonstrate that RhopH3, the smallest component of the complex, is essential for parasite survival. Conditional truncation of RhopH3 substantially reduces invasive capacity. Those mutant parasites that do invade are defective in nutrient import and die. Our results identify a dual role for RhopH3 that links erythrocyte invasion to formation of the PSAC/NPP essential for parasite survival within host erythrocytes. DOI:http://dx.doi.org/10.7554/eLife.23239.001 Malaria is a life-threatening disease that affects millions of people around the world. The parasites that cause malaria have a complex life cycle that involves infecting both mosquitoes and mammals, including humans. In humans, the parasites spend part of their life cycle inside red blood cells, which causes the symptoms of the disease. In order to survive and multiply, malaria parasites need to make the red blood cell more permeable so that it can absorb nutrients from the blood stream and get rid of the toxic waste products they generate. It remains unclear how the parasites do this, but previous research has shown that the parasites produce channel-like proteins that make red blood cells more permeable to nutrients. One of the proteins involved in this process forms part of a complex with two other proteins, called RhopH2 and RhopH3. It is not known what these other two proteins do, and whether they are necessary for creating the new nutrient channels. Sherling et al. studied the RhopH3 protein to see if it is required to make red blood cells more permeable. The experiments used a genetically modified version of the parasite, in which RhopH3 no longer interacted with the two other proteins. The findings show that RhopH3 has two important roles: first, parasites need it to invade the red blood cells, and second, parasites cannot get nutrients into the red blood cell without RhopH3. Most antimalarial drugs work by preventing parasite replication in red blood cells, but parasites are becoming increasingly resistant to these drugs. Understanding which proteins allow parasites to invade and grow within blood cells will further the development of new malaria medication. The next step will be to understand the molecular mechanisms by which RhopH3 promotes invasion and subsequently facilitates nutrient uptake, and will help researchers to explore its potential as a drug target. DOI:http://dx.doi.org/10.7554/eLife.23239.002
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Affiliation(s)
- Emma S Sherling
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Ellen Knuepfer
- Malaria Parasitology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Louis H Miller
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Christiaan van Ooij
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
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128
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Counihan NA, Chisholm SA, Bullen HE, Srivastava A, Sanders PR, Jonsdottir TK, Weiss GE, Ghosh S, Crabb BS, Creek DJ, Gilson PR, de Koning-Ward TF. Plasmodium falciparum parasites deploy RhopH2 into the host erythrocyte to obtain nutrients, grow and replicate. eLife 2017; 6. [PMID: 28252383 PMCID: PMC5365316 DOI: 10.7554/elife.23217] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/26/2017] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum parasites, the causative agents of malaria, modify their host erythrocyte to render them permeable to supplementary nutrient uptake from the plasma and for removal of toxic waste. Here we investigate the contribution of the rhoptry protein RhopH2, in the formation of new permeability pathways (NPPs) in Plasmodium-infected erythrocytes. We show RhopH2 interacts with RhopH1, RhopH3, the erythrocyte cytoskeleton and exported proteins involved in host cell remodeling. Knockdown of RhopH2 expression in cycle one leads to a depletion of essential vitamins and cofactors and decreased de novo synthesis of pyrimidines in cycle two. There is also a significant impact on parasite growth, replication and transition into cycle three. The uptake of solutes that use NPPs to enter erythrocytes is also reduced upon RhopH2 knockdown. These findings provide direct genetic support for the contribution of the RhopH complex in NPP activity and highlight the importance of NPPs to parasite survival.
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Affiliation(s)
| | | | | | - Anubhav Srivastava
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | | | - Thorey K Jonsdottir
- Burnet Institute, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia
| | | | - Sreejoyee Ghosh
- School of Medicine, Deakin University, Waurn Ponds, Australia
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia.,Monash University, Melbourne, Australia
| | - Darren J Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Paul R Gilson
- Burnet Institute, Melbourne, Australia.,Monash University, Melbourne, Australia
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129
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Chalapareddy S, Desai SA. Malaria parasite proteins involved in nutrient channels at the host erythrocyte membrane: advances and questions for future research. INTERNATIONAL JOURNAL OF CURRENT MULTIDISCIPLINARY STUDIES 2017; 3:619-623. [PMID: 28736757 PMCID: PMC5516901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Erythrocytes infected malaria parasites have increased permeability to nutrients and other solutes, as mediated by an unusual ion channel known as the plasmodial surface anion channel (PSAC). Although the increased permeability of infected erythrocytes was identified more than 70 years ago and subsequently characterized with tracer studies, its mechanism and role in parasite biology remained unclear until the introduction of patch-clamp methods and high-throughput screening technologies. These methods discovered and implicated PSAC as the primary mechanism, determined that this channel is essential for parasite development, led to identification of the channel's genes, and stimulated antimalarial drug discovery against this target. Despite these advances, many questions remain about this unusual parasite channel. Our review highlights some recent advances and describes important questions for future research.
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Affiliation(s)
- S Chalapareddy
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Gachibowli, Telangana, India 500046
| | - SA Desai
- Laboratory of Malaria and Vector Research, Division of Intramural Research, NIAID, National Institutes of Health, Rockville, MD, USA 20852
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130
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Ito D, Schureck MA, Desai SA. An essential dual-function complex mediates erythrocyte invasion and channel-mediated nutrient uptake in malaria parasites. eLife 2017; 6. [PMID: 28221136 PMCID: PMC5349850 DOI: 10.7554/elife.23485] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 02/16/2017] [Indexed: 11/27/2022] Open
Abstract
Malaria parasites evade immune detection by growth and replication within erythrocytes. After erythrocyte invasion, the intracellular pathogen must increase host cell uptake of nutrients from plasma. Here, we report that the parasite-encoded RhopH complex contributes to both invasion and channel-mediated nutrient uptake. As rhoph2 and rhoph3 gene knockouts were not viable in the human P. falciparum pathogen, we used conditional knockdowns to determine that the encoded proteins are essential and to identify their stage-specific functions. We exclude presumed roles for RhopH2 and CLAG3 in erythrocyte invasion but implicate a RhopH3 contribution either through ligand-receptor interactions or subsequent parasite internalization. These proteins then traffic via an export translocon to the host membrane, where they form a nutrient channel. Knockdown of either RhopH2 or RhopH3 disrupts the entire complex, interfering with organellar targeting and subsequent trafficking. Therapies targeting this complex should attack the pathogen at two critical points in its cycle. DOI:http://dx.doi.org/10.7554/eLife.23485.001 The parasites that cause malaria in humans and other animals infect and live inside red blood cells to escape attack by their hosts’ immune systems. Malaria parasites grow and multiply in red blood cells before bursting out and invading new red blood cells. To fuel this growth, the parasite needs access to sugars and other nutrients that are found outside in the bloodstream. Malaria parasites achieve this by inserting some of their own proteins into the membrane of the red blood cell to form an unusual channel that allows the nutrients to enter the cell. A parasite protein called CLAG3 (also known as RhopH1) is involved in formation of the unusual nutrient channel. Unlike most other proteins, malaria parasites make the CLAG3 protein while they are inside one cell and release it later when they invade a new red blood cell. The CLAG3 protein also binds to two other parasite proteins, called RhopH2 and RhopH3, to form a larger protein complex. However, it was not known what roles these other proteins played, or why the complex was made in the preceding red blood cell. Ito et al. have now addressed these unknowns by editing the genes of the parasite that causes the most dangerous form of malaria in people, a parasite called Plasmodium falciparum. These experiments revealed that the parasites could still invade host cells as normal if they lost CLAG3 and RhopH2. This suggests, that contrary to what was expected, CLAG3 and RhopH2 are not needed for the invasion process. Instead, the experiments revealed that RhopH3 serves a major role in invasion, either by helping the parasite to interact with or enter the new red blood cell. After the parasite has invaded the cell, this complex of three proteins is shuttled to the red blood cell’s membrane, where it inserts to help form the nutrient channel. The findings of Ito et al. reveal that one protein complex serves two unrelated but essential roles at different locations and time points in the life cycle of a malaria parasite. Since a parasite will not survive if it cannot enter a host cell and obtain nutrients, interfering with these processes by targeting this protein complex could lead to new therapies against malaria in the future. DOI:http://dx.doi.org/10.7554/eLife.23485.002
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Affiliation(s)
- Daisuke Ito
- Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Rockville, United States
| | - Marc A Schureck
- Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Rockville, United States
| | - Sanjay A Desai
- Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Rockville, United States
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131
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Ganter M, Goldberg JM, Dvorin JD, Paulo JA, King JG, Tripathi AK, Paul AS, Yang J, Coppens I, Jiang RH, Elsworth B, Baker DA, Dinglasan RR, Gygi SP, Duraisingh MT. Plasmodium falciparum CRK4 directs continuous rounds of DNA replication during schizogony. Nat Microbiol 2017; 2:17017. [PMID: 28211852 PMCID: PMC5328244 DOI: 10.1038/nmicrobiol.2017.17] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 01/13/2017] [Indexed: 02/08/2023]
Abstract
Plasmodium parasites, the causative agents of malaria, have evolved a unique cell division cycle in the clinically relevant asexual blood stage of infection1. DNA replication commences approximately halfway through the intracellular development following invasion and parasite growth. The schizont stage is associated with multiple rounds of DNA replication and nuclear division without cytokinesis, resulting in a multinucleated cell. Nuclei divide asynchronously through schizogony, with only the final round of DNA replication and segregation being synchronous and coordinated with daughter cell assembly2,3. However, the control mechanisms for this divergent mode of replication are unknown. Here, we show that the Plasmodium-specific kinase PfCRK4 is a key cell-cycle regulator that orchestrates multiple rounds of DNA replication throughout schizogony in Plasmodium falciparum. PfCRK4 depletion led to a complete block in nuclear division and profoundly inhibited DNA replication. Quantitative phosphoproteomic profiling identified a set of PfCRK4-regulated phosphoproteins with greatest functional similarity to CDK2 substrates, particularly proteins involved in the origin of replication firing. PfCRK4 was required for initial and subsequent rounds of DNA replication during schizogony and, in addition, was essential for development in the mosquito vector. Our results identified an essential S-phase promoting factor of the unconventional P. falciparum cell cycle. PfCRK4 is required for both a prolonged period of the intraerythrocytic stage of Plasmodium infection, as well as for transmission, revealing a broad window for PfCRK4-targeted chemotherapeutics.
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Affiliation(s)
- Markus Ganter
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jonathan M. Goldberg
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jeffrey D. Dvorin
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Division of Infectious Diseases, Boston Children’s Hospital, Boston, MA, USA
| | - Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Jonas G. King
- W. Harry Feinstone Department of Molecular Microbiology & Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Abhai K. Tripathi
- W. Harry Feinstone Department of Molecular Microbiology & Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Aditya S. Paul
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jing Yang
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Isabelle Coppens
- W. Harry Feinstone Department of Molecular Microbiology & Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Rays H.Y. Jiang
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - David A. Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Rhoel R. Dinglasan
- W. Harry Feinstone Department of Molecular Microbiology & Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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132
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Pieroni M, Azzali E, Basilico N, Parapini S, Zolkiewski M, Beato C, Annunziato G, Bruno A, Vacondio F, Costantino G. Accepting the Invitation to Open Innovation in Malaria Drug Discovery: Synthesis, Biological Evaluation, and Investigation on the Structure–Activity Relationships of Benzo[b]thiophene-2-carboxamides as Antimalarial Agents. J Med Chem 2017; 60:1959-1970. [DOI: 10.1021/acs.jmedchem.6b01685] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Nicoletta Basilico
- Dipartimento
di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università di Milano, via Pascal 36, Milano 20133, Italy
| | - Silvia Parapini
- Dipartimento
di Scienze Farmacologiche e Biomolecolari, Università di Milano, via Pascal 36, Milano 20133, Italy
| | - Michal Zolkiewski
- Department
of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | | | | | | | | | - Gabriele Costantino
- Centro
Interdipartimentale Misure (CIM) ’G. Casnati’, University of Parma, Parco Area delle Scienze 23/A, 43124 Parma, Italy
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133
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Tools for attenuation of gene expression in malaria parasites. Int J Parasitol 2017; 47:385-398. [PMID: 28153780 DOI: 10.1016/j.ijpara.2016.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/15/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022]
Abstract
An understanding of the biology of Plasmodium parasites, which are the causative agents of the disease malaria, requires study of gene function. Various reverse genetic tools have been described for determining gene function. These tools can be broadly grouped as trans- and cis-acting. Trans-acting tools control gene functions through synthetic nucleic acid probe molecules matching the sequence of the gene of interest. Once delivered to the parasite, the probe engages with the mRNA of the target gene and attenuates its function. Cis-acting tools control gene function through elements introduced into the gene of interest by DNA transfection. The expression of the modified gene can be controlled using external agents, typically small molecule ligands. In this review, we discuss the strengths and weaknesses of these tools to guide researchers in selecting the appropriate tool for studies of gene function, and for guiding future refinements of these tools.
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134
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Spillman NJ, Beck JR, Ganesan SM, Niles JC, Goldberg DE. The chaperonin TRiC forms an oligomeric complex in the malaria parasite cytosol. Cell Microbiol 2017; 19. [PMID: 28067475 DOI: 10.1111/cmi.12719] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 02/06/2023]
Abstract
The malaria parasite exports numerous proteins into its host red blood cell (RBC). The trafficking of these exported effectors is complex. Proteins are first routed through the secretory system, into the parasitophorous vacuole (PV), a membranous compartment enclosing the parasite. Proteins are then translocated across the PV membrane in a process requiring ATP and unfolding. Once in the RBC compartment the exported proteins are then refolded and further trafficked to their final localizations. Chaperones are important in the unfolding and refolding processes. Recently, it was suggested that the parasite TRiC chaperonin complex is exported, and that it is involved in trafficking of exported effectors. Using a parasite-specific antibody and epitope-tagged transgenic parasites we could observe no export of Plasmodium TRiC into the RBC. We tested the importance of the parasite TRiC by creating a regulatable knockdown line of the TRiC-θ subunit. Loss of the parasite TRiC-θ led to a severe growth defect in asexual development, but did not alter protein export into the RBC. These observations indicate that the TRiC proteins play a critical role in parasite biology, though their function, within the parasite, appears unrelated to protein trafficking in the RBC compartment.
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Affiliation(s)
- Natalie J Spillman
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, 63110, USA
| | - Josh R Beck
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, 63110, USA
| | - Suresh M Ganesan
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Daniel E Goldberg
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, 63110, USA
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135
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Tribensky A, Graf AW, Diehl M, Fleck W, Przyborski JM. Trafficking of PfExp1 to the parasitophorous vacuolar membrane of Plasmodium falciparum is independent of protein folding and the PTEX translocon. Cell Microbiol 2017; 19. [PMID: 27892646 DOI: 10.1111/cmi.12710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/19/2016] [Accepted: 11/24/2016] [Indexed: 12/13/2022]
Abstract
Having entered the mature human erythrocyte, the malaria parasite survives and propagates within a parasitophorous vacuole, a membrane-bound compartment separating the parasite from the host cell cytosol. The bounding membrane of this vacuole, referred to as the parasitophorous vacuolar membrane (PVM), contains parasite-encoded proteins, but how these membrane proteins are trafficked to the PVM remains unknown. Here, we have studied the trafficking of PfExp1 to the PVM. We find that trafficking of PfExp1 to the PVM is independent of the folding state of the protein and also continues unabated upon inactivation of the PVM translocon Plasmodium Translocon of Exported proteins (PTEX). Our data strongly suggest that the trafficking of membrane proteins to the PVM occurs by as yet unknown mechanism, potentially unique to Plasmodium.
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Affiliation(s)
- Anke Tribensky
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Andreas W Graf
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Mathias Diehl
- Department of Parasitology, University of Marburg, Marburg, Germany
| | - Wiebke Fleck
- Department of Parasitology, University of Marburg, Marburg, Germany
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136
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Hakamada K, Watanabe H, Kawano R, Noguchi K, Yohda M. Expression and characterization of the Plasmodium translocon of the exported proteins component EXP2. Biochem Biophys Res Commun 2017; 482:700-705. [DOI: 10.1016/j.bbrc.2016.11.097] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 11/16/2016] [Indexed: 10/20/2022]
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137
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Rhiel M, Bittl V, Tribensky A, Charnaud SC, Strecker M, Müller S, Lanzer M, Sanchez C, Schaeffer-Reiss C, Westermann B, Crabb BS, Gilson PR, Külzer S, Przyborski JM. Trafficking of the exported P. falciparum chaperone PfHsp70x. Sci Rep 2016; 6:36174. [PMID: 27824087 PMCID: PMC5099922 DOI: 10.1038/srep36174] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/07/2016] [Indexed: 01/20/2023] Open
Abstract
Plasmodium falciparum extensively modifies its chosen host cell, the mature human erythrocyte. This remodelling is carried out by parasite-encoded proteins that are exported into the host cell. To gain access to the human red blood cell, these proteins must cross the parasitophorous vacuole, a membrane bound compartment surrounding the parasite that is generated during the invasion process. Many exported proteins carry a so-called PEXEL/HT signal that directs their transport. We recently reported the unexpected finding of a species-restricted parasite-encoded Hsp70, termed PfHsp70x, which is exported into the host erythrocyte cytosol. PfHsp70x lacks a classical PEXEL/HT motif, and its transport appears to be mediated by a 7 amino acid motif directly following the hydrophobic N-terminal secretory signal. In this report, we analyse this short targeting sequence in detail. Surprisingly, both a reversed and scrambled version of the motif retained the capacity to confer protein export. Site directed mutagenesis of glutamate residues within this region leads to a block of protein trafficking within the lumen of the PV. In contrast to PEXEL-containing proteins, the targeting signal is not cleaved, but appears to be acetylated. Furthermore we show that, like other exported proteins, trafficking of PfHsp70x requires the vacuolar translocon, PTEX.
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Affiliation(s)
- Manuel Rhiel
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.,Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Verena Bittl
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Anke Tribensky
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Sarah C Charnaud
- Burnet Institute, Melbourne, Vic. 3004, Australia.,Monash University, Melbourne, Vic. 3800, Australia
| | - Maja Strecker
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Sebastian Müller
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
| | - Michael Lanzer
- Zentrum für Infektiologie, Parasitologie, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Cecilia Sanchez
- Zentrum für Infektiologie, Parasitologie, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Christine Schaeffer-Reiss
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR 7178, Strasbourg, France
| | - Benoit Westermann
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR 7178, Strasbourg, France
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Vic. 3004, Australia.,Monash University, Melbourne, Vic. 3800, Australia.,University of Melbourne, Melbourne, Vic. 3010, Australia
| | - Paul R Gilson
- Burnet Institute, Melbourne, Vic. 3004, Australia.,Monash University, Melbourne, Vic. 3800, Australia
| | - Simone Külzer
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany.,Research School of Biology, ANU, Acton, ACT 2601, Australia
| | - Jude M Przyborski
- Parasitology, FB Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043 Marburg, Germany
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138
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Singer M, Frischknecht F. Time for Genome Editing: Next-Generation Attenuated Malaria Parasites. Trends Parasitol 2016; 33:202-213. [PMID: 27793562 DOI: 10.1016/j.pt.2016.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/20/2016] [Accepted: 09/26/2016] [Indexed: 12/20/2022]
Abstract
Immunization with malaria parasites that developmentally arrest in or immediately after the liver stage is the only way currently known to confer sterilizing immunity in both humans and rodent models. There are various ways to attenuate parasite development resulting in different timings of arrest, which has a significant impact on vaccination efficiency. To understand what most impacts vaccination efficiency, newly developed gain-of-function methods can now be used to generate a wide array of differently attenuated parasites. The combination of multiple attenuation approaches offers the potential to engineer efficiently attenuated Plasmodium parasites and learn about their fascinating biology at the same time. Here we discuss recent studies and the potential of targeted parasite manipulation using genome editing to develop live attenuated malaria vaccines.
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Affiliation(s)
- Mirko Singer
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
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139
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Exported Epoxide Hydrolases Modulate Erythrocyte Vasoactive Lipids during Plasmodium falciparum Infection. mBio 2016; 7:mBio.01538-16. [PMID: 27795395 PMCID: PMC5082902 DOI: 10.1128/mbio.01538-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Erythrocytes are reservoirs of important epoxide-containing lipid signaling molecules, including epoxyeicosatrienoic acids (EETs). EETs function as vasodilators and anti-inflammatory modulators in the bloodstream. Bioactive EETs are hydrolyzed to less active diols (dihydroxyeicosatrienoic acids) by epoxide hydrolases (EHs). The malaria parasite Plasmodium falciparum infects host red blood cells (RBCs) and exports hundreds of proteins into the RBC compartment. In this study, we show that two parasite epoxide hydrolases, P. falciparum epoxide hydrolases 1 (PfEH1) and 2 (PfEH2), both with noncanonical serine nucleophiles, are exported to the periphery of infected RBCs. PfEH1 and PfEH2 were successfully expressed in Escherichia coli, and they hydrolyzed physiologically relevant erythrocyte EETs. Mutations in active site residues of PfEH1 ablated the ability of the enzyme to hydrolyze an epoxide substrate. Overexpression of PfEH1 or PfEH2 in parasite-infected RBCs resulted in a significant alteration in the epoxide fatty acids stored in RBC phospholipids. We hypothesize that the parasite disruption of epoxide-containing signaling lipids leads to perturbed vascular function, creating favorable conditions for binding and sequestration of infected RBCs to the microvascular endothelium. The malaria parasite exports hundreds of proteins into the erythrocyte compartment. However, for most of these proteins, their physiological function is unknown. In this study, we investigate two “hypothetical” proteins of the α/β-hydrolase fold family that share sequence similarity with epoxide hydrolases (EHs)—enzymes that destroy bioactive epoxides. Altering EH expression in parasite-infected erythrocytes resulted in a significant change in the epoxide fatty acids stored in the host cell. We propose that these EH enzymes may help the parasite to manipulate host blood vessel opening and inflame the vessel walls as they pass through the circulation system. Understanding how the malaria parasite interacts with its host RBCs will aid in our ability to combat this deadly disease.
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140
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Lucky AB, Sakaguchi M, Katakai Y, Kawai S, Yahata K, Templeton TJ, Kaneko O. Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the 'Sinton and Mulligan' Stipplings in the Cytoplasm of Monkey and Human Erythrocytes. PLoS One 2016; 11:e0164272. [PMID: 27732628 PMCID: PMC5061513 DOI: 10.1371/journal.pone.0164272] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 09/22/2016] [Indexed: 11/24/2022] Open
Abstract
The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as ‘Sinton and Mulligan’ stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum.
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Affiliation(s)
- Amuza Byaruhanga Lucky
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- Leading program, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Miako Sakaguchi
- Central Laboratory, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Yuko Katakai
- The Corporation for Production and Research of Laboratory Primates, Tsukuba 305-0843, Japan
| | - Satoru Kawai
- Department of Tropical Medicine and Parasitology, Dokkyo Medical University, Tochigi 321-0293, Japan
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Thomas J. Templeton
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York 10021, United States of America
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- Leading program, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
- * E-mail:
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141
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In Vivo Biotinylation of the Toxoplasma Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis. mBio 2016; 7:mBio.00808-16. [PMID: 27486190 PMCID: PMC4981711 DOI: 10.1128/mbio.00808-16] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that invades host cells and replicates within a unique parasitophorous vacuole. To maintain this intracellular niche, the parasite secretes an array of dense granule proteins (GRAs) into the nascent parasitophorous vacuole. These GRAs are believed to play key roles in vacuolar remodeling, nutrient uptake, and immune evasion while the parasite is replicating within the host cell. Despite the central role of GRAs in the Toxoplasma life cycle, only a subset of these proteins have been identified, and many of their roles have not been fully elucidated. In this report, we utilize the promiscuous biotin ligase BirA* to biotinylate GRA proteins secreted into the vacuole and then identify those proteins by affinity purification and mass spectrometry. Using GRA-BirA* fusion proteins as bait, we have identified a large number of known and candidate GRAs and verified localization of 13 novel GRA proteins by endogenous gene tagging. We proceeded to functionally characterize three related GRAs from this group (GRA38, GRA39, and GRA40) by gene knockout. While Δgra38 and Δgra40 parasites showed no altered phenotype, disruption of GRA39 results in slow-growing parasites that contain striking lipid deposits in the parasitophorous vacuole, suggesting a role in lipid regulation that is important for parasite growth. In addition, parasites lacking GRA39 showed dramatically reduced virulence and a lower tissue cyst burden in vivo. Together, the findings from this work reveal a partial vacuolar proteome of T. gondii and identify a novel GRA that plays a key role in parasite replication and pathogenesis. Most intracellular pathogens reside inside a membrane-bound vacuole within their host cell that is extensively modified by the pathogen to optimize intracellular growth and avoid host defenses. In Toxoplasma, this vacuole is modified by a host of secretory GRA proteins, many of which remain unidentified. Here we demonstrate that in vivo biotinylation of proximal and interacting proteins using the promiscuous biotin ligase BirA* is a powerful approach to rapidly identify vacuolar GRA proteins. We further demonstrate that one factor identified by this approach, GRA39, plays an important role in the ability of the parasite to replicate within its host cell and cause disease.
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142
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de Koning-Ward TF, Dixon MW, Tilley L, Gilson PR. Plasmodium species: master renovators of their host cells. Nat Rev Microbiol 2016; 14:494-507. [DOI: 10.1038/nrmicro.2016.79] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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143
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Gilson PR, Chisholm SA, Crabb BS, de Koning-Ward TF. Host cell remodelling in malaria parasites: a new pool of potential drug targets. Int J Parasitol 2016; 47:119-127. [PMID: 27368610 DOI: 10.1016/j.ijpara.2016.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/02/2016] [Accepted: 06/04/2016] [Indexed: 12/01/2022]
Abstract
When in their human hosts, malaria parasites spend most of their time housed within vacuoles inside erythrocytes and hepatocytes. The parasites extensively modify their host cells to obtain nutrients, prevent host cell breakdown and avoid the immune system. To perform these modifications, malaria parasites export hundreds of effector proteins into their host cells and this process is best understood in the most lethal species to infect humans, Plasmodium falciparum. The effector proteins are synthesized within the parasite and following a proteolytic cleavage event in the endoplasmic reticulum and sorting of mature proteins into the correct vesicular trafficking pathway, they are transported to the parasite surface and released into the vacuole. The effector proteins are then unfolded before extrusion across the vacuole membrane by a unique translocon complex called Plasmodium translocon of exported proteins. After gaining access to the erythrocyte cytoplasm many effector proteins continue their journey to the erythrocyte surface by utilising various membranous structures established by the parasite. This complex trafficking pathway and a large number of the effector proteins are unique to Plasmodium parasites. This pathway could, therefore, be developed as new drug targets given that protein export and the functional role of these proteins are essential for parasite survival. This review explores known and potential drug targetable steps in the protein export pathway and strategies for discovering novel drug targets.
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Affiliation(s)
- Paul R Gilson
- Burnet Institute, Melbourne, Victoria, Australia; Monash University, Melbourne, Victoria, Australia.
| | | | - Brendan S Crabb
- Burnet Institute, Melbourne, Victoria, Australia; Monash University, Melbourne, Victoria, Australia; University of Melbourne, Melbourne, Victoria, Australia
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144
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Abstract
Intracellular single-celled parasites belonging to the large phylum Apicomplexa are amongst the most prevalent and morbidity-causing pathogens worldwide. In this review, we highlight a few of the many recent advances in the field that helped to clarify some important aspects of their fascinating biology and interaction with their hosts.
Plasmodium falciparum causes malaria, and thus the recent emergence of resistance against the currently used drug combinations based on artemisinin has been of major interest for the scientific community. It resulted in great advances in understanding the resistance mechanisms that can hopefully be translated into altered future drug regimens. Apicomplexa are also experts in host cell manipulation and immune evasion.
Toxoplasma gondii and
Theileria sp., besides
Plasmodium sp., are species that secrete effector molecules into the host cell to reach this aim. The underlying molecular mechanisms for how these proteins are trafficked to the host cytosol (
T. gondii and
Plasmodium) and how a secreted protein can immortalize the host cell (
Theileria sp.) have been illuminated recently. Moreover, how such secreted proteins affect the host innate immune responses against
T. gondii and the liver stages of
Plasmodium has also been unraveled at the genetic and molecular level, leading to unexpected insights. Methodological advances in metabolomics and molecular biology have been instrumental to solving some fundamental puzzles of mitochondrial carbon metabolism in Apicomplexa. Also, for the first time, the generation of stably transfected
Cryptosporidium parasites was achieved, which opens up a wide variety of experimental possibilities for this understudied, important apicomplexan pathogen.
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Affiliation(s)
- Frank Seeber
- FG16: Mycotic and parasitic agents and mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Svenja Steinfelder
- Institute of Immunology, Center of Infection Medicine, Free University Berlin, Berlin, Germany
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145
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Zainabadi K. Malaria Parasite CLAG3, a Protein Linked to Nutrient Channels, Participates in High Molecular Weight Membrane-Associated Complexes in the Infected Erythrocyte. PLoS One 2016; 11:e0157390. [PMID: 27299521 PMCID: PMC4907441 DOI: 10.1371/journal.pone.0157390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/27/2016] [Indexed: 11/24/2022] Open
Abstract
Malaria infected erythrocytes show increased permeability to a number of solutes important for parasite growth as mediated by the Plasmodial Surface Anion Channel (PSAC). The P. falciparum clag3 genes have recently been identified as key determinants of PSAC, though exactly how they contribute to channel function and whether additional host/parasite proteins are required remain unknown. To begin to answer these questions, I have taken a biochemical approach. Here I have used an epitope-tagged CLAG3 parasite to perform co-immunoprecipitation experiments using membrane fractions of infected erythrocytes. Native PAGE and mass spectrometry studies reveal that CLAG3 participate in at least three different high molecular weight complexes: a ~720kDa complex consisting of CLAG3, RHOPH2 and RHOPH3; a ~620kDa complex consisting of CLAG3 and RHOPH2; and a ~480kDa complex composed solely of CLAG3. Importantly, these complexes can be found throughout the parasite lifecycle but are absent in untransfected controls. Extracellular biotin labeling and protease susceptibility studies localize the 480kDa complex to the erythrocyte membrane. This complex, likely composed of a homo-oligomer of 160kDa CLAG3, may represent a functional subunit, possibly the pore, of PSAC.
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Affiliation(s)
- Kayvan Zainabadi
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, NIH, Rockville, Maryland, United States of America
- * E-mail:
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146
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Plasmodium falciparum Histidine-Rich Protein II Compromises Brain Endothelial Barriers and May Promote Cerebral Malaria Pathogenesis. mBio 2016; 7:mBio.00617-16. [PMID: 27273825 PMCID: PMC4959673 DOI: 10.1128/mbio.00617-16] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cerebral malaria (CM) is a disease of the vascular endothelium caused by Plasmodium falciparum. It is characterized by parasite sequestration, inflammatory cytokine production, and vascular leakage. A distinguishing feature of P. falciparum infection is parasite production and secretion of histidine-rich protein II (HRPII). Plasma HRPII is a diagnostic and prognostic marker for falciparum malaria. We demonstrate that disruption of a human cerebral microvascular endothelial barrier by P. falciparum-infected erythrocytes depends on expression of HRPII. Purified recombinant or native HRPII can recapitulate these effects. HRPII action occurs via activation of the inflammasome, resulting in decreased integrity of tight junctions and increased endothelial permeability. We propose that HRPII is a virulence factor that may contribute to cerebral malaria by compromising endothelial barrier integrity within the central nervous system. Cerebral malaria is a devastating disease. Patients have high levels of the protein HRPII in their blood. We have found that endothelial cell barriers become leaky when treated with concentrations of HRPII similar to those found in patients. This result suggests that HRPII may be important in cerebral malaria. Our finding that HRPII functions by causing inflammation suggests points of intervention for therapy or vaccination against this disease.
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147
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The machinery underlying malaria parasite virulence is conserved between rodent and human malaria parasites. Nat Commun 2016; 7:11659. [PMID: 27225796 PMCID: PMC4894950 DOI: 10.1038/ncomms11659] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 04/18/2016] [Indexed: 02/07/2023] Open
Abstract
Sequestration of red blood cells infected with the human malaria parasite Plasmodium falciparum in organs such as the brain is considered important for pathogenicity. A similar phenomenon has been observed in mouse models of malaria, using the rodent parasite Plasmodium berghei, but it is unclear whether the P. falciparum proteins known to be involved in this process are conserved in the rodent parasite. Here we identify the P. berghei orthologues of two such key factors of P. falciparum, SBP1 and MAHRP1. Red blood cells infected with P. berghei parasites lacking SBP1 or MAHRP1a fail to bind the endothelial receptor CD36 and show reduced sequestration and virulence in mice. Complementation of the mutant P. berghei parasites with the respective P. falciparum SBP1 and MAHRP1 orthologues restores sequestration and virulence. These findings reveal evolutionary conservation of the machinery underlying sequestration of divergent malaria parasites and support the notion that the P. berghei rodent model is an adequate tool for research on malaria virulence. Proteins SBP1 and MAHRP1 of the human malaria parasite are required for sequestration of infected red blood cells in major organs. Here, De Niz et al. identify homologous proteins in the rodent parasite Plasmodium berghei, showing that they play similar roles and supporting the usefulness of malaria mouse models.
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148
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Przyborski JM, Nyboer B, Lanzer M. Ticket to ride: export of proteins to the Plasmodium falciparum-infected erythrocyte. Mol Microbiol 2016; 101:1-11. [PMID: 26996123 DOI: 10.1111/mmi.13380] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2016] [Indexed: 12/28/2022]
Abstract
The malaria parasite Plasmodium falciparum exports numerous proteins to its chosen host cell, the mature human erythrocyte. Many of these proteins are important for parasite survival. To reach the host cell, parasites must cross multiple membrane barriers and then furthermore be targeted to their correct sub-cellular localisation. This novel transport pathway has received much research attention in the past decades, especially as many of the mechanisms are expected to be parasite-specific and thus potential targets for drug development. In this article we summarize some of the most recent advances in this field, and highlight areas in which further research is needed.
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Affiliation(s)
- Jude M Przyborski
- Parasitology, Faculty of Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043, Marburg, Germany
| | - Britta Nyboer
- Center of Infectious Diseases, Parasitology, Heidelberg University, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Heidelberg University, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
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149
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Mesén-Ramírez P, Reinsch F, Blancke Soares A, Bergmann B, Ullrich AK, Tenzer S, Spielmann T. Stable Translocation Intermediates Jam Global Protein Export in Plasmodium falciparum Parasites and Link the PTEX Component EXP2 with Translocation Activity. PLoS Pathog 2016; 12:e1005618. [PMID: 27168322 PMCID: PMC4864081 DOI: 10.1371/journal.ppat.1005618] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 04/17/2016] [Indexed: 11/25/2022] Open
Abstract
Protein export is central for the survival and virulence of intracellular P. falciparum blood stage parasites. To reach the host cell, exported proteins cross the parasite plasma membrane (PPM) and the parasite-enclosing parasitophorous vacuole membrane (PVM), a process that requires unfolding, suggestive of protein translocation. Components of a proposed translocon at the PVM termed PTEX are essential in this phase of export but translocation activity has not been shown for the complex and questions have been raised about its proposed membrane pore component EXP2 for which no functional data is available in P. falciparum. It is also unclear how PTEX mediates trafficking of both, soluble as well as transmembrane proteins. Taking advantage of conditionally foldable domains, we here dissected the translocation events in the parasite periphery, showing that two successive translocation steps are needed for the export of transmembrane proteins, one at the PPM and one at the PVM. Our data provide evidence that, depending on the length of the C-terminus of the exported substrate, these steps occur by transient interaction of the PPM and PVM translocon, similar to the situation for protein transport across the mitochondrial membranes. Remarkably, we obtained constructs of exported proteins that remained arrested in the process of being translocated across the PVM. This clogged the translocation pore, prevented the export of all types of exported proteins and, as a result, inhibited parasite growth. The substrates stuck in translocation were found in a complex with the proposed PTEX membrane pore component EXP2, suggesting a role of this protein in translocation. These data for the first time provide evidence for EXP2 to be part of a translocating entity, suggesting that PTEX has translocation activity and provide a mechanistic framework for the transport of soluble as well as transmembrane proteins from the parasite boundary into the host cell. P. falciparum parasites, the deadliest agent of human malaria, develop within erythrocytes where they are surrounded by a parasitophorous vacuolar membrane (PVM). To ensure intracellular survival, the parasite exports a large repertoire of proteins into the host cell. Exported proteins require unfolding for trafficking across the membrane boundaries separating the parasite from the erythrocyte, typical for transport by protein translocating membrane channels. Here, we dissected the sequence of translocation events at the parasite boundary using substrates that can be conditionally arrested at translocation steps. We for the first time obtained exported proteins arrested in the process of being translocated across the PVM. This jammed the translocons for all other types of exported proteins and inhibited parasite growth. The constructs stuck in translocation were in a complex with EXP2, a component of a complex known to be essential for protein export that is termed PTEX. Our work links the need for unfolding and the function of this complex in export, giving experimental evidence that PTEX indeed is a translocon. Conditionally unfoldable domains have been instrumental in unravelling transport processes across membranes and here resolve the transport steps the different kinds of exported proteins require to reach the P. falciparum-infected host cell.
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Affiliation(s)
- Paolo Mesén-Ramírez
- Bernhard Nocht Institute for Tropical Medicine, Parasitology section, Hamburg, Germany
| | - Ferdinand Reinsch
- Bernhard Nocht Institute for Tropical Medicine, Parasitology section, Hamburg, Germany
| | | | - Bärbel Bergmann
- Bernhard Nocht Institute for Tropical Medicine, Parasitology section, Hamburg, Germany
| | - Ann-Katrin Ullrich
- Bernhard Nocht Institute for Tropical Medicine, Parasitology section, Hamburg, Germany
| | - Stefan Tenzer
- Institute for Immunology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Tobias Spielmann
- Bernhard Nocht Institute for Tropical Medicine, Parasitology section, Hamburg, Germany
- * E-mail:
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150
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Protein trafficking in apicomplexan parasites: crossing the vacuolar Rubicon. Curr Opin Microbiol 2016; 32:38-45. [PMID: 27155394 DOI: 10.1016/j.mib.2016.04.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/08/2016] [Accepted: 04/12/2016] [Indexed: 01/01/2023]
Abstract
Although apicomplexans like the blood stages of Plasmodium and the actively replicating 'tachyzoite' stage of Toxoplasma infect very dissimilar host cells, recent studies suggest they share molecular commonalities amongst differences at the parasitophorous vacuolar membrane (PVM) surrounding these intracellular parasites. A protein translocation export (PTEX) complex in the PVM of Plasmodium, is functionally informed by findings in Toxoplasma. Lipids play a role in trafficking to and across the PVM. Toxoplasma exploit an orthologue of a plasmodial secretory aspartyl protease but substrate cleavage yields a signal for targeting to the PVM, rather than directly to the host cell. The studies significantly advance understanding of how trafficking to and across the host-pathogen PVM boundary induces virulence and disease in different host milieu.
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