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Translocation of effector proteins into host cells by Toxoplasma gondii. Curr Opin Microbiol 2019; 52:130-138. [PMID: 31446366 DOI: 10.1016/j.mib.2019.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/19/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022]
Abstract
The Apicomplexan parasite, Toxoplasma gondii, is an obligate intracellular organism that must co-opt its host cell to survive. To this end, Toxoplasma parasites introduce a suite of effector proteins from two secretory compartments called rhoptries and dense granules into the host cells. Once inside, these effectors extensively modify the host cell to facilitate parasite penetration, replication and persistence. In this review, we summarize the most recent advances in current understanding of effector translocation from Toxoplasma's rhoptry and dense granule organelles into the host cell, with comparisons to Plasmodium spp. for broader context.
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52
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Chitama BYA, Miyazaki S, Zhu X, Kagaya W, Yahata K, Kaneko O. Multiple charged amino acids of Plasmodium falciparum SURFIN4.1 N-terminal region are important for efficient export to the red blood cell. Parasitol Int 2019; 71:186-193. [DOI: 10.1016/j.parint.2019.04.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 11/17/2022]
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53
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Takano R, Kozuka-Hata H, Kondoh D, Bochimoto H, Oyama M, Kato K. A High-Resolution Map of SBP1 Interactomes in Plasmodium falciparum-infected Erythrocytes. iScience 2019; 19:703-714. [PMID: 31476617 PMCID: PMC6728614 DOI: 10.1016/j.isci.2019.07.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 05/09/2019] [Accepted: 07/19/2019] [Indexed: 11/19/2022] Open
Abstract
The pathogenesis of malaria parasites depends on host erythrocyte modifications that are facilitated by parasite proteins exported to the host cytoplasm. These exported proteins form a trafficking complex in the host cytoplasm that transports virulence determinants to the erythrocyte surface; this complex is thus essential for malaria virulence. Here, we report a comprehensive interaction network map of this complex. We developed authentic, unbiased, highly sensitive proteomic approaches to determine the proteins that interact with a core component of the complex, SBP1 (skeleton-binding protein 1). SBP1 interactomes revealed numerous exported proteins and potential interactors associated with SBP1 intracellular trafficking. We identified several host-parasite protein interactions and linked the exported protein MAL8P1.4 to Plasmodium falciparum virulence in infected erythrocytes. Our study highlights the complicated interplay between parasite and host proteins in the host cytoplasm and provides an interaction dataset connecting dozens of exported proteins required for P. falciparum virulence. We used shotgun proteomics to identify SBP1-interacting factors System validation showed complex interplay between parasite and host proteins Our system can be used to explore protozoan parasite virulence in erythrocytes
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Affiliation(s)
- Ryo Takano
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Hiroko Kozuka-Hata
- Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Daisuke Kondoh
- Laboratory of Veterinary Anatomy, Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Hiroki Bochimoto
- Health Care Administration Center, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Masaaki Oyama
- Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Kentaro Kato
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan; Laboratory of Sustainable Animal Environment, Graduate School of Agricultural Science, Tohoku University, Naruko-onsen, Osaki, Miyagi 989-6711, Japan.
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54
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Ngotho P, Soares AB, Hentzschel F, Achcar F, Bertuccini L, Marti M. Revisiting gametocyte biology in malaria parasites. FEMS Microbiol Rev 2019; 43:401-414. [PMID: 31220244 PMCID: PMC6606849 DOI: 10.1093/femsre/fuz010] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 04/05/2019] [Indexed: 12/21/2022] Open
Abstract
Gametocytes are the only form of the malaria parasite that is transmissible to the mosquito vector. They are present at low levels in blood circulation and significant knowledge gaps exist in their biology. Recent reductions in the global malaria burden have brought the possibility of elimination and eradication, with renewed focus on malaria transmission biology as a basis for interventions. This review discusses recent insights into gametocyte biology in the major human malaria parasite, Plasmodium falciparum and related species.
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Affiliation(s)
- Priscilla Ngotho
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120 University Road, Glasgow G12 8TA, UK
| | - Alexandra Blancke Soares
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120 University Road, Glasgow G12 8TA, UK
| | - Franziska Hentzschel
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120 University Road, Glasgow G12 8TA, UK
| | - Fiona Achcar
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120 University Road, Glasgow G12 8TA, UK
| | - Lucia Bertuccini
- Core Facilities, Microscopy Area, Instituto Superiore di Sanita, Via Regina Elena 299, 00161 Rome, Italy
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120 University Road, Glasgow G12 8TA, UK.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston 02115, MA, USA
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55
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Matthews KM, Kalanon M, de Koning-Ward TF. Uncoupling the Threading and Unfoldase Actions of Plasmodium HSP101 Reveals Differences in Export between Soluble and Insoluble Proteins. mBio 2019; 10:e01106-19. [PMID: 31164473 PMCID: PMC6550532 DOI: 10.1128/mbio.01106-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 12/02/2022] Open
Abstract
Plasmodium parasites must export proteins into their erythrocytic host to survive. Exported proteins must cross the parasite plasma membrane (PPM) and the parasitophorous vacuolar membrane (PVM) encasing the parasite to access the host cell. Crossing the PVM requires protein unfolding and passage through a translocon, the Plasmodium translocon of exported proteins (PTEX). In this study, we provide the first direct evidence that heat shock protein 101 (HSP101), a core component of PTEX, unfolds proteins for translocation across the PVM by creating transgenic Plasmodium parasites in which the unfoldase and translocation functions of HSP101 have become uncoupled. Strikingly, while these parasites could export native proteins, they were unable to translocate soluble, tightly folded reporter proteins bearing the Plasmodium export element (PEXEL) across the PVM into host erythrocytes under the same conditions. In contrast, an identical PEXEL reporter protein but harboring a transmembrane domain could be exported, suggesting that a prior unfolding step occurs at the PPM. Together, these results demonstrate that the export of parasite proteins is dependent on how these proteins are presented to the secretory pathway before they reach PTEX as well as their folded status. Accordingly, only tightly folded soluble proteins secreted into the vacuolar space and not proteins containing transmembrane domains or the majority of erythrocyte-stage exported proteins have an absolute requirement for the full unfoldase activity of HSP101 to be exported.IMPORTANCE The Plasmodium parasites that cause malaria export hundreds of proteins into their host red blood cell (RBC). These exported proteins drastically alter the structural and functional properties of the RBC and play critical roles in parasite virulence and survival. To access the RBC cytoplasm, parasite proteins must pass through the Plasmodium translocon of exported proteins (PTEX) located at the membrane interfacing the parasite and host cell. Our data provide evidence that HSP101, a component of PTEX, serves to unfold protein cargo requiring translocation. We also reveal that addition of a transmembrane domain to soluble cargo influences its ability to be translocated by parasites in which the HSP101 motor and unfolding activities have become uncoupled. Therefore, we propose that proteins with transmembrane domains use an alternative unfolding pathway prior to PTEX to facilitate export.
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Affiliation(s)
| | - Ming Kalanon
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
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56
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Yield improvement and enzymatic dissection of Plasmodium falciparum plasmepsin V. Mol Biochem Parasitol 2019; 231:111188. [PMID: 31108131 DOI: 10.1016/j.molbiopara.2019.111188] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/13/2019] [Accepted: 05/15/2019] [Indexed: 11/22/2022]
Abstract
To survive within a red blood cell (RBC), malaria parasites establish striking modifications to the permeability, rigidity and cytoadherence properties of the host cell. This is mediated by the export of hundreds of proteins from the parasite into the erythrocyte. Plasmodium falciparum plasmepsin V (PfPMV), is an ER resident aspartic protease that processes proteins for export into the host erythrocyte, plays a crucial role in parasite virulence and survival and is considered a potential malaria drug target. Most attempts at its heterologous expression in Escherichia coli have resulted in mainly the production of insoluble proteins. In this study, we employed a multipurpose fusion tag to improve the production of PfPMV in E. coli. Recombinant PfPMVm, comprising residues 84-521, was substantially obtained in soluble form and could be purified in a single step, yielding a 3.7-fold increase in purified PfPMVm compared to previous reports. Additionally, we have mutated the catalytic residues (D118N and D365N), individually and together, and the unpaired cysteine residue C178 to evaluate the effects on catalytic efficiency. Mutation of D365 had more pronounced effects on the catalytic efficiency than that of D118, suggesting that the D365 may act as a catalytic nucleophile to activate the water molecule. The importance of C178 was also confirmed by the inhibition by metal ions, indicating that C178 is partially involved in the substrate recognition. Collectively, our results describe an improved system to produce recombinant PfPMVm in E. coli and dissect the amino acids involved in catalysis and substrate recognition.
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57
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Affiliation(s)
- Martin R Pool
- School of Biological Sciences, Faculty of Biology Medicine and Health, Health Innovation Manchester, University of Manchester, Manchester, UK.
| | - Ilaria Russo
- Infectious Diseases, Washington University School of Medicine, St Louis, MO, USA.
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58
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Matthews KM, Pitman EL, de Koning-Ward TF. Illuminating how malaria parasites export proteins into host erythrocytes. Cell Microbiol 2019; 21:e13009. [PMID: 30656810 DOI: 10.1111/cmi.13009] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/06/2018] [Accepted: 12/17/2018] [Indexed: 12/11/2022]
Abstract
Plasmodium parasites that cause the disease malaria have developed an elaborate trafficking pathway to facilitate the export of hundreds of effector proteins into their host cell, the erythrocyte. In this review, we outline how certain effector proteins contribute to parasite survival, virulence, and immune evasion. We also highlight how parasite proteins destined for export are recognised at the endoplasmic reticulum to facilitate entry into the export pathway and how the effector proteins are able to transverse the bounding parasitophorous vaculoar membrane via the Plasmodium translocon of exported proteins to gain access to the host cell. Some of the gaps in our understanding of the export pathway are also presented. Finally, we examine the degree of conservation of some of the key components of the Plasmodium export pathway in closely related apicomplexan parasites, which may provide insight into how the diverse apicomplexan parasites have adapted to survival pressures encountered within their respective host cells.
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Affiliation(s)
| | - Ethan L Pitman
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
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59
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Boonyalai N, Collins CR, Hackett F, Withers-Martinez C, Blackman MJ. Essentiality of Plasmodium falciparum plasmepsin V. PLoS One 2018; 13:e0207621. [PMID: 30517136 PMCID: PMC6281190 DOI: 10.1371/journal.pone.0207621] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/02/2018] [Indexed: 11/19/2022] Open
Abstract
The malaria parasite replicates within erythrocytes. The pathogenesis of clinical malaria is in large part due to the capacity of the parasite to remodel its host cell. To do this, intraerythrocytic stages of Plasmodium falciparum export more than 300 proteins that dramatically alter the morphology of the infected erythrocyte as well as its mechanical and adhesive properties. P. falciparum plasmepsin V (PfPMV) is an aspartic protease that processes proteins for export into the host erythrocyte and is thought to play a key role in parasite virulence and survival. However, although standard techniques for gene disruption as well as conditional protein knockdown have been previously attempted with the pfpmv gene, complete gene removal or knockdown was not achieved so direct genetic proof that PMV is an essential protein has not been established. Here we have used a conditional gene excision approach combining CRISPR-Cas9 gene editing and DiCre-mediated recombination to functionally inactivate the pfpmv gene. The resulting mutant parasites displayed a severe growth defect. Detailed phenotypic analysis showed that development of the mutant parasites was arrested early in the ring-to-trophozoite transition in the erythrocytic cycle following gene excision. Our findings are the first to elucidate the effects of PMV gene disruption, showing that it is essential for parasite viability in asexual blood stages. The mutant parasites can now be used as a platform to further dissect the Plasmodium protein export pathway.
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Affiliation(s)
- Nonlawat Boonyalai
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, Thailand
- * E-mail: (NB), ; (MJB)
| | - Christine R. Collins
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Fiona Hackett
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| | | | - 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
- * E-mail: (NB), ; (MJB)
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60
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Tohmoto T, Takashima E, Takeo S, Morita M, Nagaoka H, Udomsangpetch R, Sattabongkot J, Ishino T, Torii M, Tsuboi T. Anti-MSP11 IgG inhibits Plasmodium falciparum merozoite invasion into erythrocytes in vitro. Parasitol Int 2018; 69:25-29. [PMID: 30385417 DOI: 10.1016/j.parint.2018.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/18/2018] [Accepted: 10/29/2018] [Indexed: 11/19/2022]
Abstract
Merozoite surface proteins (MSPs) are considered as promising blood-stage malaria vaccine candidates. MSP3 has long been evaluated for its vaccine candidacy, however, the candidacy of other members of MSP3 family is insufficiently characterized. Here, we investigated Plasmodium falciparum MSP11 (PF3D7_1036000), a member of the MSP3 family, for its potential as a blood-stage vaccine candidate. The full-length protein (MSP11-FL) as well as the N-terminal half-MSP11 (MSP11-N), known to be unique among the MSP3 family members, were expressed by wheat germ cell-free system, and used to raise antibodies in rabbit. Immunoblot analysis of schizont lysates probed with anti-MSP11-N antibodies detected double bands at approximately 40 and 60 kDa, consistent with the previous report thus confirming antibodies specificity. However, inconsistent with previously reported merozoite's surface localization, immunofluorescence assay (IFA) revealed that MSP11 likely localizes to rhoptry neck of merozoites in mature schizonts. After invasion, MSP11 localized to parasitophorous vacuole and thereafter in Maurer's clefts in trophozoites. Anti-MSP11-FL antibody levels were significantly higher in asymptomatic than symptomatic P. falciparum cases in malaria low endemic Thailand. This reconfirmed that anti-MSP11 antibodies play an important role in protection against clinical malaria, as previously reported. Furthermore, in vitro growth inhibition assay revealed that anti-MSP11-FL rabbit antibodies biologically function by inhibiting merozoite invasion of erythrocytes. These findings further support the vaccine candidacy of MSP11.
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Affiliation(s)
- Tatsuhiro Tohmoto
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
| | - Satoru Takeo
- Division of Tropical Diseases and Parasitology, Department of Infectious Diseases, Faculty of Medicine, Kyorin University, Mitaka, Tokyo 181-8611, Japan
| | - Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Rachanee Udomsangpetch
- Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Salaya, Nakhosn Pathom 73170, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Tomoko Ishino
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Motomi Torii
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
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61
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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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62
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Sittikul P, Songtawee N, Kongkathip N, Boonyalai N. In vitro and in silico studies of naphthoquinones and peptidomimetics toward Plasmodium falciparum plasmepsin V. Biochimie 2018; 152:159-173. [PMID: 30103899 DOI: 10.1016/j.biochi.2018.07.002] [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: 02/21/2018] [Accepted: 07/04/2018] [Indexed: 12/16/2022]
Abstract
Plasmodium proteases play both regulatory and effector roles in essential biological processes in this important pathogen and have long been investigated as drug targets. Plasmepsin V from P. falciparum (PfPMV) is an essential protease that processes proteins for export into the host erythrocyte and is a focus of ongoing drug development efforts. In the present study, recombinant protein production, inhibition assays, binding studies as well as molecular docking and molecular dynamics simulation studies were used to investigate the mode of binding of a PEXEL-based peptidomimetic and naphthoquinone compounds to PfPMV. Consistent with our previous study, refolded PfPMVs were produced with functional characteristics similar to the soluble counterpart. Naphthoquinone compounds inhibited PfPMV activity by 50% at 50 μM but did not affect pepsin activity. The IC50 values of compounds 31 and 37 against PfPMV were 22.25 and 68.94 μM, respectively. Molecular dynamics simulations revealed that PEXEL peptide interacted with PfPMV active site residues via electrostatic interactions while naphthoquinone binding preferred van der Waal interactions. P1'-Ser of the PfEMP2 substrate formed an additional H-bond with Asp365 promoting the catalytic efficiency. Additionally, the effect of metal ions on the secondary structure of PfPMV was examined. Our results confirmed that Hg2+ ions reversibly induced the changes in secondary structure of the protein whereas Fe3+ ions induced irreversibly. No change was observed in the presence of Ca2+ ions. Overall, the results here suggested that naphthoquinone derivatives may represent another source of antimalarial inhibitors targeting aspartic proteases but further chemical modifications are required.
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Affiliation(s)
- Pichamon Sittikul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand; Department of Tropical Pediatrics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Napat Songtawee
- Department of Clinical Chemistry, Faculty of Medical Technology, Mahidol University, Phuttamonthon, Nakhon Pathom, 73170, Thailand
| | - Ngampong Kongkathip
- Natural Product and Organic Synthesis Research Unit (NPOS), Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Nonlawat Boonyalai
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
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63
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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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64
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Nguyen W, Hodder AN, de Lezongard RB, Czabotar PE, Jarman KE, O'Neill MT, Thompson JK, Jousset Sabroux H, Cowman AF, Boddey JA, Sleebs BE. Enhanced antimalarial activity of plasmepsin V inhibitors by modification of the P 2 position of PEXEL peptidomimetics. Eur J Med Chem 2018; 154:182-198. [PMID: 29800827 DOI: 10.1016/j.ejmech.2018.05.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 12/26/2022]
Abstract
Plasmepsin V is an aspartyl protease that plays a critical role in the export of proteins bearing the Plasmodium export element (PEXEL) motif (RxLxQ/E/D) to the infected host erythrocyte, and thus the survival of the malaria parasite. Previously, development of transition state PEXEL mimetic inhibitors of plasmepsin V have primarily focused on demonstrating the importance of the P3 Arg and P1 Leu in binding affinity and selectivity. Here, we investigate the importance of the P2 position by incorporating both natural and non-natural amino acids into this position and show disubstituted beta-carbon amino acids convey the greatest potency. Consequently, we show analogues with either cyclohexylglycine or phenylglycine in the P2 position are the most potent inhibitors of plasmepsin V that impair processing of the PEXEL motif in exported proteins resulting in death of P. falciparum asexual stage parasites.
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Affiliation(s)
- William Nguyen
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Anthony N Hodder
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Richard Bestel de Lezongard
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Kate E Jarman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Matthew T O'Neill
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia
| | - Jennifer K Thompson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia
| | - Helene Jousset Sabroux
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Justin A Boddey
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia
| | - Brad E Sleebs
- The Walter and Eliza Hall Institute of Medical Research, Parkville, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, 3010, Australia.
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65
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Davies HM, Nofal SD, McLaughlin EJ, Osborne AR. Repetitive sequences in malaria parasite proteins. FEMS Microbiol Rev 2018; 41:923-940. [PMID: 29077880 DOI: 10.1093/femsre/fux046] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 09/13/2017] [Indexed: 12/13/2022] Open
Abstract
Five species of parasite cause malaria in humans with the most severe disease caused by Plasmodium falciparum. Many of the proteins encoded in the P. falciparum genome are unusually enriched in repetitive low-complexity sequences containing a limited repertoire of amino acids. These repetitive sequences expand and contract dynamically and are among the most rapidly changing sequences in the genome. The simplest repetitive sequences consist of single amino acid repeats such as poly-asparagine tracts that are found in approximately 25% of P. falciparum proteins. More complex repeats of two or more amino acids are also common in diverse parasite protein families. There is no universal explanation for the occurrence of repetitive sequences and it is possible that many confer no function to the encoded protein and no selective advantage or disadvantage to the parasite. However, there are increasing numbers of examples where repetitive sequences are important for parasite protein function. We discuss the diverse roles of low-complexity repetitive sequences throughout the parasite life cycle, from mediating protein-protein interactions to enabling the parasite to evade the host immune system.
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Affiliation(s)
- Heledd M Davies
- The Francis Crick Institute, London, NW1 1AT, United Kingdom
| | - Stephanie D Nofal
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom
| | - Emilia J McLaughlin
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Andrew R Osborne
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom.,Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, Malet Street, London, WC1E 7HX, United Kingdom
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66
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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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67
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Zhang M, Faou P, Maier AG, Rug M. Plasmodium falciparum exported protein PFE60 influences Maurer’s clefts architecture and virulence complex composition. Int J Parasitol 2018; 48:83-95. [DOI: 10.1016/j.ijpara.2017.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/20/2017] [Accepted: 09/06/2017] [Indexed: 11/30/2022]
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68
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Structural analysis of P. falciparum KAHRP and PfEMP1 complexes with host erythrocyte spectrin suggests a model for cytoadherent knob protrusions. PLoS Pathog 2017; 13:e1006552. [PMID: 28806784 PMCID: PMC5570508 DOI: 10.1371/journal.ppat.1006552] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/24/2017] [Accepted: 07/25/2017] [Indexed: 11/19/2022] Open
Abstract
Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) and Knob-associated Histidine-rich Protein (KAHRP) are directly linked to malaria pathology. PfEMP1 and KAHRP cluster on protrusions (knobs) on the P. falciparum-infected erythrocyte surface and enable pathogenic cytoadherence of infected erythrocytes to the host microvasculature, leading to restricted blood flow, oxygen deprivation and damage of tissues. Here we characterize the interactions of PfEMP1 and KAHRP with host erythrocyte spectrin using biophysical, structural and computational approaches. These interactions assist knob formation and, thus, promote cytoadherence. We show that the folded core of the PfEMP1 cytosolic domain interacts broadly with erythrocyte spectrin but shows weak, residue-specific preference for domain 17 of α spectrin, which is proximal to the erythrocyte cytoskeletal junction. In contrast, a protein sequence repeat region in KAHRP preferentially associates with domains 10–14 of β spectrin, proximal to the spectrin–ankyrin complex. Structural models of PfEMP1 and KAHRP with spectrin combined with previous microscopy and protein interaction data suggest a model for knob architecture. Formation of cytoadherent knobs on the surface of P. falciparum infected erythrocytes correlates with malaria pathology. Two parasite proteins central for knob formation and cytoadherence, KAHRP and PfEMP1, have previously been shown to bind the erythrocyte cytoskeleton. Both KAHRP and PfEMP1 include large segments of protein disorder, which have previously hampered their analysis. In this study we use biophysics and structural biology tools to analyze the interactions between these proteins and host spectrin. We devise a novel computational tool to help us towards this goal that may be broadly applicable to characterizing other complexes of widespread, disordered Plasmodial proteins and host components. We derive atomistic models of KAHRP–spectrin and PfEMP1 –spectrin complexes, and integrate these into an emerging model of knob architecture.
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69
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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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70
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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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71
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Chan S, Frasch A, Mandava CS, Ch'ng JH, Quintana MDP, Vesterlund M, Ghorbal M, Joannin N, Franzén O, Lopez-Rubio JJ, Barbieri S, Lanzavecchia A, Sanyal S, Wahlgren M. Regulation of PfEMP1-VAR2CSA translation by a Plasmodium translation-enhancing factor. Nat Microbiol 2017; 2:17068. [PMID: 28481333 DOI: 10.1038/nmicrobiol.2017.68] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/29/2017] [Indexed: 12/22/2022]
Abstract
Pregnancy-associated malaria commonly involves the binding of Plasmodium falciparum-infected erythrocytes to placental chondroitin sulfate A (CSA) through the PfEMP1-VAR2CSA protein. VAR2CSA is translationally repressed by an upstream open reading frame. In this study, we report that the P. falciparum translation enhancing factor (PTEF) relieves upstream open reading frame repression and thereby facilitates VAR2CSA translation. VAR2CSA protein levels in var2csa-transcribing parasites are dependent on the expression level of PTEF, and the alleviation of upstream open reading frame repression requires the proteolytic processing of PTEF by PfCalpain. Cleavage generates a C-terminal domain that contains a sterile-alpha-motif-like domain. The C-terminal domain is permissive to cytoplasmic shuttling and interacts with ribosomes to facilitate translational derepression of the var2csa coding sequence. It also enhances translation in a heterologous translation system and thus represents the first non-canonical translation enhancing factor to be found in a protozoan. Our results implicate PTEF in regulating placental CSA binding of infected erythrocytes.
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Affiliation(s)
- Sherwin Chan
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden
| | - Alejandra Frasch
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden
| | - Chandra Sekhar Mandava
- Department of Cell and Molecular Biology, Uppsala University, Box-596, 751 24 Uppsala, Sweden
| | - Jun-Hong Ch'ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden.,Department of Microbiology, National University of Singapore 117545, Singapore
| | - Maria Del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden.,Escuela de Medicina y Ciencias de la Salud, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Calle 12C No. 6-25, Bogotá, Colombia
| | - Mattias Vesterlund
- Cancer Proteomics, Department of Oncology-Pathology, Karolinska Institutet, 17176 Stockholm, Sweden
| | - Mehdi Ghorbal
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier F34090, France.,CNRS - 5290, IRD 224 - University of Montpellier (UMR 'MiVEGEC'), Montpellier, France
| | - Nicolas Joannin
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden
| | - Oscar Franzén
- Department of Genetics and Genomic Sciences, Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Jose-Juan Lopez-Rubio
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier F34090, France.,CNRS - 5290, IRD 224 - University of Montpellier (UMR 'MiVEGEC'), Montpellier, France
| | - Sonia Barbieri
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona 6500, Switzerland
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona 6500, Switzerland.,Institute of Microbiology, ETH Zurich, Zurich 8093, Switzerland
| | - Suparna Sanyal
- Department of Cell and Molecular Biology, Uppsala University, Box-596, 751 24 Uppsala, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, 171 77 Stockholm, Sweden
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72
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Birnbaum J, Flemming S, Reichard N, Soares AB, Mesén-Ramírez P, Jonscher E, Bergmann B, Spielmann T. A genetic system to study Plasmodium falciparum protein function. Nat Methods 2017; 14:450-456. [DOI: 10.1038/nmeth.4223] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 02/06/2017] [Indexed: 02/07/2023]
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73
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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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74
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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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75
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Davies HM, Thalassinos K, Osborne AR. Expansion of Lysine-rich Repeats in Plasmodium Proteins Generates Novel Localization Sequences That Target the Periphery of the Host Erythrocyte. J Biol Chem 2016; 291:26188-26207. [PMID: 27777305 PMCID: PMC5207086 DOI: 10.1074/jbc.m116.761213] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Indexed: 01/05/2023] Open
Abstract
Repetitive low complexity sequences, mostly assumed to have no function, are common in proteins that are exported by the malaria parasite into its host erythrocyte. We identify a group of exported proteins containing short lysine-rich tandemly repeated sequences that are sufficient to localize to the erythrocyte periphery, where key virulence-related modifications to the plasma membrane and the underlying cytoskeleton are known to occur. Efficiency of targeting is dependent on repeat number, indicating that novel targeting modules could evolve by expansion of short lysine-rich sequences. Indeed, analysis of fragments of GARP from different species shows that two novel targeting sequences have arisen via the process of repeat expansion in this protein. In the protein Hyp12, the targeting function of a lysine-rich sequence is masked by a neighboring repetitive acidic sequence, further highlighting the importance of repetitive low complexity sequences. We show that sequences capable of targeting the erythrocyte periphery are present in at least nine proteins from Plasmodium falciparum and one from Plasmodium knowlesi. We find these sequences in proteins known to be involved in erythrocyte rigidification and cytoadhesion as well as in previously uncharacterized exported proteins. Together, these data suggest that expansion and contraction of lysine-rich repeats could generate targeting sequences de novo as well as modulate protein targeting efficiency and function in response to selective pressure.
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Affiliation(s)
- Heledd M Davies
- From the Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck and University College London, London WC1E 6BT, United Kingdom
| | - Konstantinos Thalassinos
- From the Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck and University College London, London WC1E 6BT, United Kingdom
| | - Andrew R Osborne
- From the Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck and University College London, London WC1E 6BT, United Kingdom
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76
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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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77
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Plasmodium Helical Interspersed Subtelomeric (PHIST) Proteins, at the Center of Host Cell Remodeling. Microbiol Mol Biol Rev 2016; 80:905-27. [PMID: 27582258 DOI: 10.1128/mmbr.00014-16] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the asexual cycle, Plasmodium falciparum extensively remodels the human erythrocyte to make it a suitable host cell. A large number of exported proteins facilitate this remodeling process, which causes erythrocytes to become more rigid, cytoadherent, and permeable for nutrients and metabolic products. Among the exported proteins, a family of 89 proteins, called the Plasmodium helical interspersed subtelomeric (PHIST) protein family, has been identified. While also found in other Plasmodium species, the PHIST family is greatly expanded in P. falciparum. Although a decade has passed since their first description, to date, most PHIST proteins remain uncharacterized and are of unknown function and localization within the host cell, and there are few data on their interactions with other host or parasite proteins. However, over the past few years, PHIST proteins have been mentioned in the literature at an increasing rate owing to their presence at various localizations within the infected erythrocyte. Expression of PHIST proteins has been implicated in molecular and cellular processes such as the surface display of PfEMP1, gametocytogenesis, changes in cell rigidity, and also cerebral and pregnancy-associated malaria. Thus, we conclude that PHIST proteins are central to host cell remodeling, but despite their obvious importance in pathology, PHIST proteins seem to be understudied. Here we review current knowledge, shed light on the definition of PHIST proteins, and discuss these proteins with respect to their localization and probable function. We take into consideration interaction studies, microarray analyses, or data from blood samples from naturally infected patients to combine all available information on this protein family.
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78
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Siau A, Huang X, Weng M, Sze SK, Preiser PR. Proteome mapping of Plasmodium: identification of the P. yoelii remodellome. Sci Rep 2016; 6:31055. [PMID: 27503796 PMCID: PMC4977464 DOI: 10.1038/srep31055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/13/2016] [Indexed: 11/17/2022] Open
Abstract
Plasmodium associated virulence in the host is linked to extensive remodelling of the host erythrocyte by parasite proteins that form the “remodellome”. However, without a common motif or structure available to identify these proteins, little is known about the proteins that are destined to reside in the parasite periphery, the host-cell cytoplasm and/or the erythrocyte membrane. Here, the subcellular fractionation of erythrocytic P. yoelii at trophozoite and schizont stage along with label-free quantitative LC-MS/MS analysis of the whole proteome, revealed a proteome of 1335 proteins. Differential analysis of the relative abundance of these proteins across the subcellular compartments allowed us to map their locations, independently of their predicted features. These results, along with literature data and in vivo validation of 61 proteins enabled the identification of a remodellome of 184 proteins. This approach identified a significant number of conserved remodelling proteins across plasmodium that likely represent key conserved functions in the parasite and provides new insights into parasite evolution and biology.
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Affiliation(s)
- Anthony Siau
- Nanyang Technological University, School of Biological Sciences, 637551, Singapore
| | - Ximei Huang
- Nanyang Technological University, School of Biological Sciences, 637551, Singapore
| | - Mei Weng
- Nanyang Technological University, School of Biological Sciences, 637551, Singapore
| | - Siu Kwan Sze
- Nanyang Technological University, School of Biological Sciences, 637551, Singapore
| | - Peter R Preiser
- Nanyang Technological University, School of Biological Sciences, 637551, Singapore
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79
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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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80
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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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81
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Elsworth B, Sanders PR, Nebl T, Batinovic S, Kalanon M, Nie CQ, Charnaud SC, Bullen HE, de Koning Ward TF, Tilley L, Crabb BS, Gilson PR. Proteomic analysis reveals novel proteins associated with the Plasmodium protein exporter PTEX and a loss of complex stability upon truncation of the core PTEX component, PTEX150. Cell Microbiol 2016; 18:1551-1569. [PMID: 27019089 DOI: 10.1111/cmi.12596] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 03/11/2016] [Accepted: 03/22/2016] [Indexed: 11/28/2022]
Abstract
The Plasmodium translocon for exported proteins (PTEX) has been established as the machinery responsible for the translocation of all classes of exported proteins beyond the parasitophorous vacuolar membrane of the intraerythrocytic malaria parasite. Protein export, particularly in the asexual blood stage, is crucial for parasite survival as exported proteins are involved in remodelling the host cell, an essential process for nutrient uptake, waste removal and immune evasion. Here, we have truncated the conserved C-terminus of one of the essential PTEX components, PTEX150, in Plasmodium falciparum in an attempt to create mutants of reduced functionality. Parasites tolerated C-terminal truncations of up to 125 amino acids with no reduction in growth, protein export or the establishment of new permeability pathways. Quantitative proteomic approaches however revealed a decrease in other PTEX subunits associating with PTEX150 in truncation mutants, suggesting a role for the C-terminus of PTEX150 in regulating PTEX stability. Our analyses also reveal three previously unreported PTEX-associated proteins, namely PV1, Pf113 and Hsp70-x (respective PlasmoDB numbers; PF3D7_1129100, PF3D7_1420700 and PF3D7_0831700) and demonstrate that core PTEX proteins exist in various distinct multimeric forms outside the major complex.
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Affiliation(s)
- Brendan Elsworth
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia.,Monash University, Melbourne, VIC, 3800, Australia
| | - Paul R Sanders
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Thomas Nebl
- Walter & Eliza Hall Institute, Melbourne, VIC, 3052, Australia
| | - Steven Batinovic
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC, Australia.,ARC Centre of Excellence for Coherent X-ray Science, The University of Melbourne, Melbourne, VIC, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | | | - Catherine Q Nie
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Sarah C Charnaud
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia.,Monash University, Melbourne, VIC, 3800, Australia
| | - Hayley E Bullen
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia
| | | | - Leann Tilley
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC, Australia.,ARC Centre of Excellence for Coherent X-ray Science, The University of Melbourne, Melbourne, VIC, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Brendan S Crabb
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia.,Monash University, Melbourne, VIC, 3800, Australia.,University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Paul R Gilson
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia. .,Monash University, Melbourne, VIC, 3800, Australia.
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82
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Oberli A, Zurbrügg L, Rusch S, Brand F, Butler ME, Day JL, Cutts EE, Lavstsen T, Vakonakis I, Beck HP. Plasmodium falciparum Plasmodium helical interspersed subtelomeric proteins contribute to cytoadherence and anchor P. falciparum erythrocyte membrane protein 1 to the host cell cytoskeleton. Cell Microbiol 2016; 18:1415-28. [PMID: 26916885 PMCID: PMC5103180 DOI: 10.1111/cmi.12583] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/15/2016] [Accepted: 02/21/2016] [Indexed: 01/12/2023]
Abstract
Adherence of Plasmodium falciparum‐infected erythrocytes to host endothelium is conferred through the parasite‐derived virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), the major contributor to malaria severity. PfEMP1 located at knob structures on the erythrocyte surface is anchored to the cytoskeleton, and the Plasmodium helical interspersed subtelomeric (PHIST) gene family plays a role in many host cell modifications including binding the intracellular domain of PfEMP1. Here, we show that conditional reduction of the PHIST protein PFE1605w strongly reduces adhesion of infected erythrocytes to the endothelial receptor CD36. Adhesion to other endothelial receptors was less affected or even unaltered by PFE1605w depletion, suggesting that PHIST proteins might be optimized for subsets of PfEMP1 variants. PFE1605w does not play a role in PfEMP1 transport, but it directly interacts with both the intracellular segment of PfEMP1 and with cytoskeletal components. This is the first report of a PHIST protein interacting with key molecules of the cytoadherence complex and the host cytoskeleton, and this functional role seems to play an essential role in the pathology of P. falciparum.
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Affiliation(s)
- Alexander Oberli
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Laura Zurbrügg
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Sebastian Rusch
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Françoise Brand
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Jemma L Day
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Erin E Cutts
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of International Health, Immunology, and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | | | - Hans-Peter Beck
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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83
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Role of the ER and Golgi in protein export by Apicomplexa. Curr Opin Cell Biol 2016; 41:18-24. [PMID: 27019341 DOI: 10.1016/j.ceb.2016.03.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/31/2022]
Abstract
Apicomplexan parasites cause diseases of medical and agricultural importance linked to dramatic changes they impart upon infected host cells. Following invasion, the malaria parasite Plasmodium falciparum renovates the host erythrocyte using mechanisms previously believed to be malaria-specific. This involves proteolytic cleavage of effectors in the endoplasmic reticulum that licences proteins for translocation into the host cell. Recently, it was demonstrated that the related parasite Toxoplasma gondii, responsible for disease in immunocompromised individuals and congenital birth defects, has an analogous pathway with some differences, including proteolytic processing in the Golgi. Here we review the similarities and distinctions in export mechanisms between these and other Apicomplexan parasites to reconcile how this group of pathogens modify their host cells to survive and proliferate.
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84
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Soni R, Sharma D, Bhatt TK. Plasmodium falciparum Secretome in Erythrocyte and Beyond. Front Microbiol 2016; 7:194. [PMID: 26925057 PMCID: PMC4759260 DOI: 10.3389/fmicb.2016.00194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/05/2016] [Indexed: 01/19/2023] Open
Abstract
Plasmodium falciparum is the causative agent of deadly malaria disease. It is an intracellular eukaryote and completes its multi-stage life cycle spanning the two hosts viz, mosquito and human. In order to habituate within host environment, parasite conform several strategies to evade host immune responses such as surface antigen polymorphism or modulation of host immune system and it is mediated by secretion of proteins from parasite to the host erythrocyte and beyond, collectively known as, malaria secretome. In this review, we will discuss about the deployment of parasitic secretory protein in mechanism implicated for immune evasion, protein trafficking, providing virulence, changing permeability and cyto-adherence of infected erythrocyte. We will be covering the possibilities of developing malaria secretome as a drug/vaccine target. This gathered information will be worthwhile in depicting a well-organized picture for host-pathogen interplay during the malaria infection and may also provide some clues for the development of novel anti-malarial therapies.
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Affiliation(s)
- Rani Soni
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Rajasthan, India
| | - Drista Sharma
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Rajasthan, India
| | - Tarun K Bhatt
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Rajasthan, India
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85
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Chisholm SA, McHugh E, Lundie R, Dixon MWA, Ghosh S, O’Keefe M, Tilley L, Kalanon M, de Koning-Ward TF. Contrasting Inducible Knockdown of the Auxiliary PTEX Component PTEX88 in P. falciparum and P. berghei Unmasks a Role in Parasite Virulence. PLoS One 2016; 11:e0149296. [PMID: 26886275 PMCID: PMC4757573 DOI: 10.1371/journal.pone.0149296] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/29/2016] [Indexed: 12/21/2022] Open
Abstract
Pathogenesis of malaria infections is linked to remodeling of erythrocytes, a process dependent on the trafficking of hundreds of parasite-derived proteins into the host erythrocyte. Recent studies have demonstrated that the Plasmodium translocon of exported proteins (PTEX) serves as the central gateway for trafficking of these proteins, as inducible knockdown of the core PTEX constituents blocked the trafficking of all classes of cargo into the erythrocyte. However, the role of the auxiliary component PTEX88 in protein export remains less clear. Here we have used inducible knockdown technologies in P. falciparum and P. berghei to assess the role of PTEX88 in parasite development and protein export, which reveal that the in vivo growth of PTEX88-deficient parasites is hindered. Interestingly, we were unable to link this observation to a general defect in export of a variety of known parasite proteins, suggesting that PTEX88 functions in a different fashion to the core PTEX components. Strikingly, PTEX88-deficient P. berghei were incapable of causing cerebral malaria despite a robust pro-inflammatory response from the host. These parasites also exhibited a reduced ability to sequester in peripheral tissues and were removed more readily from the circulation by the spleen. In keeping with these findings, PTEX88-deficient P. falciparum-infected erythrocytes displayed reduced binding to the endothelial cell receptor, CD36. This suggests that PTEX88 likely plays a specific direct or indirect role in mediating parasite sequestration rather than making a universal contribution to the trafficking of all exported proteins.
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Affiliation(s)
- Scott A. Chisholm
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
| | - Emma McHugh
- Department of Biochemistry and Molecular Biology, Bio21 Institute, Melbourne, Victoria, Australia
| | - Rachel Lundie
- The Burnet Institute, Melbourne, Victoria, Australia
| | - Matthew W. A. Dixon
- Department of Biochemistry and Molecular Biology, Bio21 Institute, Melbourne, Victoria, Australia
| | - Sreejoyee Ghosh
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
| | | | - Leann Tilley
- Department of Biochemistry and Molecular Biology, Bio21 Institute, Melbourne, Victoria, Australia
| | - Ming Kalanon
- School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia
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86
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Export of malaria proteins requires co-translational processing of the PEXEL motif independent of phosphatidylinositol-3-phosphate binding. Nat Commun 2016; 7:10470. [PMID: 26832821 PMCID: PMC4740378 DOI: 10.1038/ncomms10470] [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: 05/08/2015] [Accepted: 12/09/2015] [Indexed: 11/08/2022] Open
Abstract
Plasmodium falciparum exports proteins into erythrocytes using the Plasmodium export element (PEXEL) motif, which is cleaved in the endoplasmic reticulum (ER) by plasmepsin V (PMV). A recent study reported that phosphatidylinositol-3-phosphate (PI(3)P) concentrated in the ER binds to PEXEL motifs and is required for export independent of PMV, and that PEXEL motifs are functionally interchangeable with RxLR motifs of oomycete effectors. Here we show that the PEXEL does not bind PI(3)P, and that this lipid is not concentrated in the ER. We find that RxLR motifs cannot mediate export in P. falciparum. Parasites expressing a mutated version of KAHRP, with the PEXEL motif repositioned near the signal sequence, prevented PMV cleavage. This mutant possessed the putative PI(3)P-binding residues but is not exported. Reinstatement of PEXEL to its original location restores processing by PMV and export. These results challenge the PI(3)P hypothesis and provide evidence that PEXEL position is conserved for co-translational processing and export.
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87
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Sappakhaw K, Takasila R, Sittikul P, Wattana-Amorn P, Assavalapsakul W, Boonyalai N. Biochemical characterization of plasmepsin V from Plasmodium vivax Thailand isolates: Substrate specificity and enzyme inhibition. Mol Biochem Parasitol 2016; 204:51-63. [PMID: 26795263 DOI: 10.1016/j.molbiopara.2016.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 01/05/2016] [Accepted: 01/08/2016] [Indexed: 12/19/2022]
Abstract
Plasmepsin V (PMV) is a Plasmodium aspartic protease responsible for the cleavage of the Plasmodium export element (PEXEL) motif, which is an essential step for export of PEXEL containing proteins and crucial for parasite viability. Here we describe the genetic polymorphism of Plasmodium vivax PMV (PvPMV) Thailand isolates, followed by cloning, expression, purification and characterization of PvPMV-Thai, presenting the pro- and mature-form of PvPMV-Thai. With our refolding and purification method, approximately 1mg of PvPMV-Thai was obtained from 1g of washed inclusion bodies. Unlike PvPMV-Ind and PvPMV-Sal-1, PvPMV-Thai contains a four-amino acid insertion (SVSE) at residues 246-249. We have confirmed that this insertion did not interfere with the catalytic activity as it is located in the long loop (R241-E272) pointing away from the substrate-binding pocket. PvPMV-Thai exhibited similar activity to PfPMV counterparts in which PfEMP2 could be hydrolyzed more efficiently than HRPII. Substrate specificity studies at P1' showed that replacing Ser by Val or Glu of the PfEMP2 peptide markedly reduced the enzyme activity of PvPMV similar to that of PfPMV whereas replacing His by Val or Ser of the HRPII peptide increased the cleavage activity. However, the substitution of amino acids at the P2 position with Glu dramatically reduced the cleavage efficiency by 80% in PvPMV in contrast to 30% in PfPMV, indicating subtle differences around the S2 binding pocket of both PfPMV and PvPMV. Four inhibitors were also evaluated for PvPMV-Thai activity including PMSF, pepstatin A, nelfinavir, and menisporopsin A-a macrocyclic polylactone. We are the first to show that menisporopsin A partially inhibits the PvPMV-Thai activity at high concentration. Taken together, these findings provide insights into recombinant production, substrate specificity and inhibition of PvPMV-Thai.
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Affiliation(s)
- Khomkrit Sappakhaw
- Department of Biochemistry, Special Research Unit for Protein Engineering and Protein Bioinformatics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand
| | - Ratchaneekorn Takasila
- Department of Biochemistry, Special Research Unit for Protein Engineering and Protein Bioinformatics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand
| | - Pichamon Sittikul
- Department of Biochemistry, Special Research Unit for Protein Engineering and Protein Bioinformatics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand
| | - Pakorn Wattana-Amorn
- Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand; Department of Chemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand
| | - Wanchai Assavalapsakul
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Nonlawat Boonyalai
- Department of Biochemistry, Special Research Unit for Protein Engineering and Protein Bioinformatics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand; Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok 10900, Thailand.
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88
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Ramakrishnan G, Srinivasan N, Padmapriya P, Natarajan V. Homology-Based Prediction of Potential Protein-Protein Interactions between Human Erythrocytes and Plasmodium falciparum. Bioinform Biol Insights 2015; 9:195-206. [PMID: 26740742 PMCID: PMC4689366 DOI: 10.4137/bbi.s31880] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 11/08/2015] [Accepted: 11/14/2015] [Indexed: 12/21/2022] Open
Abstract
Plasmodium falciparum, a causative agent of malaria, is a well-characterized obligate intracellular parasite known for its ability to remodel host cells, particularly erythrocytes, to successfully persist in the host environment. However, the current levels of understanding from the laboratory experiments on the host–parasite interactions and the strategies pursued by the parasite to remodel host erythrocytes are modest. Several computational means developed in the recent past to predict host–parasite/pathogen interactions have generated testable hypotheses on feasible protein–protein interactions. We demonstrate the utility of protein structure-based protocol in the recognition of potential interacting proteins across P. falciparum and host erythrocytes. In concert with the information on the expression and subcellular localization of host and parasite proteins, we have identified 208 biologically feasible interactions potentially brought about by 59 P. falciparum and 30 host erythrocyte proteins. For selected cases, we have evaluated the physicochemical viability of the predicted interactions in terms of surface complementarity, electrostatic complementarity, and interaction energies at protein interface regions. Such careful inspection of molecular and mechanistic details generates high confidence on the predicted host–parasite protein–protein interactions. The predicted host–parasite interactions generate many experimentally testable hypotheses that can contribute to the understanding of possible mechanisms undertaken by the parasite in host erythrocyte remodeling. Thus, the key protein players recognized in P. falciparum can be explored for their usefulness as targets for chemotherapeutic intervention.
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Affiliation(s)
- Gayatri Ramakrishnan
- Indian Institute of Science Mathematics Initiative, Indian Institute of Science, Bangalore, India.; Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | | | - Ponnan Padmapriya
- Department of Physics, Indian Institute of Science, Bangalore, India
| | - Vasant Natarajan
- Department of Physics, Indian Institute of Science, Bangalore, India
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89
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Malaria Parasite Proteins and Their Role in Alteration of the Structure and Function of Red Blood Cells. ADVANCES IN PARASITOLOGY 2015; 91:1-86. [PMID: 27015947 DOI: 10.1016/bs.apar.2015.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Malaria, caused by Plasmodium spp., continues to be a major threat to human health and a significant cause of socioeconomic hardship in many countries. Almost half of the world's population live in malaria-endemic regions and many of them suffer one or more, often life-threatening episodes of malaria every year, the symptoms of which are attributable to replication of the parasite within red blood cells (RBCs). In the case of Plasmodium falciparum, the species responsible for most malaria-related deaths, parasite replication within RBCs is accompanied by striking alterations to the morphological, biochemical and biophysical properties of the host cell that are essential for the parasites' survival. To achieve this, the parasite establishes a unique and extensive protein export network in the infected RBC, dedicating at least 6% of its genome to the process. Understanding the full gamut of proteins involved in this process and the mechanisms by which P. falciparum alters the structure and function of RBCs is important both for a more complete understanding of the pathogenesis of malaria and for development of new therapeutic strategies to prevent or treat this devastating disease. This review focuses on what is currently known about exported parasite proteins, their interactions with the RBC and their likely pathophysiological consequences.
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90
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Spielmann T, Gilberger TW. Critical Steps in Protein Export of Plasmodium falciparum Blood Stages. Trends Parasitol 2015; 31:514-525. [DOI: 10.1016/j.pt.2015.06.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 06/16/2015] [Accepted: 06/24/2015] [Indexed: 11/29/2022]
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91
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Curt-Varesano A, Braun L, Ranquet C, Hakimi MA, Bougdour A. The aspartyl protease TgASP5 mediates the export of the Toxoplasma GRA16 and GRA24 effectors into host cells. Cell Microbiol 2015; 18:151-67. [PMID: 26270241 DOI: 10.1111/cmi.12498] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/27/2015] [Indexed: 12/21/2022]
Abstract
Toxoplasma gondii and Plasmodium species are obligatory intracellular parasites that export proteins into the infected cells in order to interfere with host-signalling pathways, acquire nutrients or evade host defense mechanisms. With regard to export mechanism, a wealth of information in Plasmodium spp. is available, while the mechanisms operating in T. gondii remain uncertain. The recent discovery of exported proteins in T. gondii, mainly represented by dense granule resident proteins, might explain this discrepancy and offers a unique opportunity to study the export mechanism in T. gondii. Here, we report that GRA16 export is mediated by two protein elements present in its N-terminal region. Because the first element contains a putative Plasmodium export element linear motif (RRLAE), we hypothesized that GRA16 export depended on a maturation process involving protein cleavage. Using both N- and C-terminal epitope tags, we provide evidence for protein proteolysis occurring in the N-terminus of GRA16. We show that TgASP5, the T. gondii homolog of Plasmodium plasmepsin V, is essential for GRA16 export and is directly responsible for its maturation in a Plasmodium export element-dependent manner. Interestingly, TgASP5 is also involved in GRA24 export, although the GRA24 maturation mechanism is TgASP5-independent. Our data reveal different modus operandi for protein export, in which TgASP5 should play multiple functions.
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Affiliation(s)
- Aurélie Curt-Varesano
- Laboratoire Adaptation et Pathogénie des Microorganismes, Centre National de la Recherche Scientifique, UMR5163, F-38041, Grenoble, France.,Université Joseph Fourier, F-38000, Grenoble Cedex 09, France
| | - Laurence Braun
- Laboratoire Adaptation et Pathogénie des Microorganismes, Centre National de la Recherche Scientifique, UMR5163, F-38041, Grenoble, France.,Université Joseph Fourier, F-38000, Grenoble Cedex 09, France
| | - Caroline Ranquet
- Bâtiment B - Biologie, BGene Genetics SAS, 2280 rue de la Piscine, 38400, Saint Martin d'Hères, France
| | - Mohamed-Ali Hakimi
- Laboratoire Adaptation et Pathogénie des Microorganismes, Centre National de la Recherche Scientifique, UMR5163, F-38041, Grenoble, France.,Université Joseph Fourier, F-38000, Grenoble Cedex 09, France
| | - Alexandre Bougdour
- Laboratoire Adaptation et Pathogénie des Microorganismes, Centre National de la Recherche Scientifique, UMR5163, F-38041, Grenoble, France.,Université Joseph Fourier, F-38000, Grenoble Cedex 09, France
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92
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Birch CM, Hou HW, Han J, Niles JC. Identification of malaria parasite-infected red blood cell surface aptamers by inertial microfluidic SELEX (I-SELEX). Sci Rep 2015; 5:11347. [PMID: 26126714 PMCID: PMC4486934 DOI: 10.1038/srep11347] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 05/14/2015] [Indexed: 01/09/2023] Open
Abstract
Plasmodium falciparum malaria parasites invade and remodel human red blood cells (RBCs) by trafficking parasite-synthesized proteins to the RBC surface. While these proteins mediate interactions with host cells that contribute to disease pathogenesis, the infected RBC surface proteome remains poorly characterized. Here we use a novel strategy (I-SELEX) to discover high affinity aptamers that selectively recognize distinct epitopes uniquely present on parasite-infected RBCs. Based on inertial focusing in spiral microfluidic channels, I-SELEX enables stringent partitioning of cells (efficiency ≥ 106) from unbound oligonucleotides at high volume throughput (~2 × 106 cells min−1). Using an RBC model displaying a single, non-native antigen and live malaria parasite-infected RBCs as targets, we establish suitability of this strategy for de novo aptamer selections. We demonstrate recovery of a diverse set of aptamers that recognize distinct, surface-displayed epitopes on parasite-infected RBCs with nanomolar affinity, including an aptamer against the protein responsible for placental sequestration, var2CSA. These findings validate I-SELEX as a broadly applicable aptamer discovery platform that enables identification of new reagents for mapping the parasite-infected RBC surface proteome at higher molecular resolution to potentially contribute to malaria diagnostics, therapeutics and vaccine efforts.
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Affiliation(s)
- Christina M Birch
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Han Wei Hou
- 1] Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA [2] BioSystems and Micromechanics (BioSyM) IRG, Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 Create Way, #04-13/14 Enterprise Wing, Singapore 138602, SINGAPORE
| | - Jongyoon Han
- 1] Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA [2] Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA [3] BioSystems and Micromechanics (BioSyM) IRG, Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 Create Way, #04-13/14 Enterprise Wing, Singapore 138602, SINGAPORE
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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93
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Przyborski JM, Diehl M, Blatch GL. Plasmodial HSP70s are functionally adapted to the malaria parasite life cycle. Front Mol Biosci 2015; 2:34. [PMID: 26167469 PMCID: PMC4481151 DOI: 10.3389/fmolb.2015.00034] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/12/2015] [Indexed: 11/13/2022] Open
Abstract
The human malaria parasite, Plasmodium falciparum, encodes a minimal complement of six heat shock protein 70s (PfHSP70s), some of which are highly expressed and are thought to play an important role in the survival and pathology of the parasite. In addition to canonical features of molecular chaperones, these HSP70s possess properties that reflect functional adaptation to a parasitic life style, including resistance to thermal insult during fever periods and host–parasite interactions. The parasite even exports an HSP70 to the host cell where it is likely to be involved in host cell modification. This review focuses on the features of the PfHSP70s, particularly with respect to their adaptation to the malaria parasite life cycle.
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Affiliation(s)
| | - Mathias Diehl
- Parasitology, Philipps University Marburg Marburg, Germany
| | - Gregory L Blatch
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University Melbourne, VIC, Australia ; Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University Grahamstown, South Africa
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94
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Perrin AJ, Bartholdson SJ, Wright GJ. P-selectin is a host receptor for Plasmodium MSP7 ligands. Malar J 2015; 14:238. [PMID: 26045295 PMCID: PMC4478713 DOI: 10.1186/s12936-015-0750-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/26/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium parasites typically elicit a non-sterile but protective immune response in human host populations, suggesting that the parasites actively modulate normal immunological mechanisms. P-selectin is a cell surface receptor expressed in mammals, that is a known component of the inflammatory response against pathogens and has been previously identified as a host factor that influences malaria-associated pathology both in human patients and rodent infection models. METHODS To better understand the molecular mechanisms underlying the involvement of P-selectin in the pathogenesis of malaria, a systematic extracellular protein interaction screen was used to identify Plasmodium falciparum merozoite surface protein 7 (MSP7) as a binding partner of human P-selectin. This interaction, and those occurring between P-selectin and Plasmodium MSP7 homologues, was characterized biochemically. RESULTS Plasmodium falciparum MSP7 and P-selectin were shown to bind each other directly via the N-terminus of PfMSP7 and the P-selectin C-type lectin and EGF-like domains. Orthologous proteins in the murine parasite Plasmodium berghei (PbMSRP1 and PbMSRP2) and mouse P-selectin also interacted. Finally, P-selectin, when complexed with MSP7, could no longer bind to its endogenous carbohydrate ligand, Sialyl-Lewis(X). CONCLUSIONS Novel interactions were identified between Plasmodium MSP7 protein family members and host P-selectin receptors. Since PfMSP7 could prevent interactions between P-selectin and its leukocyte ligands, these results provide a possible mechanism for the known immunomodulatory effects of both MSP7 and P-selectin in malaria infection models.
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Affiliation(s)
- Abigail J Perrin
- Cell Surface Signalling Laboratory and Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK.
| | - S Josefin Bartholdson
- Cell Surface Signalling Laboratory and Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK.
| | - Gavin J Wright
- Cell Surface Signalling Laboratory and Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK.
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95
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Schulze J, Kwiatkowski M, Borner J, Schlüter H, Bruchhaus I, Burmester T, Spielmann T, Pick C. The Plasmodium falciparum exportome contains non-canonical PEXEL/HT proteins. Mol Microbiol 2015; 97:301-14. [PMID: 25850860 DOI: 10.1111/mmi.13024] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2015] [Indexed: 11/29/2022]
Abstract
The pathogenicity of Plasmodium falciparum is partly due to parasite-induced host cell modifications. These modifications are facilitated by exported P. falciparum proteins, collectively referred to as the exportome. Export of several hundred proteins is mediated by the PEXEL/HT, a protease cleavage site. The PEXEL/HT is usually comprised of five amino acids, of which R at position 1, L at position 3 and E, D or Q at position 5 are conserved and important for export. Non-canonical PEXEL/HTs with K or H at position 1 and/or I at position 3 are presently considered non-functional. Here, we show that non-canonical PEXEL/HT proteins are overrepresented in P. falciparum and other Plasmodium species. Furthermore, we show that non-canonical PEXEL/HTs can be cleaved and can promote export in both a REX3 and a GBP reporter, but not in a KAHRP reporter, indicating that non-canonical PEXEL/HTs are functional in concert with a supportive sequence environment. We then selected P. falciparum proteins with a non-canonical PEXEL/HT and show that some of these proteins are exported and that their export depends on non-canonical PEXEL/HTs. We conclude that PEXEL/HT plasticity is higher than appreciated and that non-canonical PEXEL/HT proteins cannot categorically be excluded from Plasmodium exportome predictions.
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Affiliation(s)
- Jana Schulze
- University of Hamburg, Institute of Zoology, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Marcel Kwiatkowski
- Department of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, D-20246, Hamburg, Germany
| | - Janus Borner
- University of Hamburg, Institute of Zoology, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Hartmut Schlüter
- Department of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, D-20246, Hamburg, Germany
| | - Iris Bruchhaus
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, D-20359, Hamburg, Germany
| | - Thorsten Burmester
- University of Hamburg, Institute of Zoology, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Tobias Spielmann
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, D-20359, Hamburg, Germany
| | - Christian Pick
- University of Hamburg, Institute of Zoology, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
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96
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Ramdani G, Naissant B, Thompson E, Breil F, Lorthiois A, Dupuy F, Cummings R, Duffier Y, Corbett Y, Mercereau-Puijalon O, Vernick K, Taramelli D, Baker DA, Langsley G, Lavazec C. cAMP-Signalling Regulates Gametocyte-Infected Erythrocyte Deformability Required for Malaria Parasite Transmission. PLoS Pathog 2015; 11:e1004815. [PMID: 25951195 PMCID: PMC4423841 DOI: 10.1371/journal.ppat.1004815] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 03/13/2015] [Indexed: 12/31/2022] Open
Abstract
Blocking Plasmodium falciparum transmission to mosquitoes has been designated a strategic objective in the global agenda of malaria elimination. Transmission is ensured by gametocyte-infected erythrocytes (GIE) that sequester in the bone marrow and at maturation are released into peripheral blood from where they are taken up during a mosquito blood meal. Release into the blood circulation is accompanied by an increase in GIE deformability that allows them to pass through the spleen. Here, we used a microsphere matrix to mimic splenic filtration and investigated the role of cAMP-signalling in regulating GIE deformability. We demonstrated that mature GIE deformability is dependent on reduced cAMP-signalling and on increased phosphodiesterase expression in stage V gametocytes, and that parasite cAMP-dependent kinase activity contributes to the stiffness of immature gametocytes. Importantly, pharmacological agents that raise cAMP levels in transmissible stage V gametocytes render them less deformable and hence less likely to circulate through the spleen. Therefore, phosphodiesterase inhibitors that raise cAMP levels in P. falciparum infected erythrocytes, such as sildenafil, represent new candidate drugs to block transmission of malaria parasites. Malaria transmission is ensured by deformable mature gametocyte-infected erythrocytes being taken up when a mosquito bites. Non-deformable immature gametocyte stages are sequestered in the bone marrow, as their lack of deformability would lead to their splenic clearance. In the present study, we apply nano-filtration technology to mimic splenic retention and demonstrate that deformability of transmissible mature stage V gametocytes is regulated by parasite cyclic AMP-dependent kinase signalling. Importantly, when we used drugs to raise cAMP levels we render transmissible mature gametocytes as stiff as non-transmissible gametocytes. In contrast, when we inhibit the cAMP-dependent kinase we render immature gametocytes more deformable. Thus, by two different approaches we confirm that the drop in cAMP levels in mature gametocytes leads to an increase in their deformability and hence more likely to circulate through the spleen. Our molecular observations have the potential to be translated into therapies for blocking malaria transmission by demonstrating that raising cAMP levels with sildenafil also known as “Viagra” renders mature gametocytes rigid. These findings provide the proof of principle that deformability of circulating gametocytes is targetable by pharmacological agents and as such, it provides a novel approach to prevent the spread of parasites. PDE inhibitors therefore represent novel drug leads potentially capable of blocking transmission and improving the worldwide fight to eliminate malaria from the human population.
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Affiliation(s)
- Ghania Ramdani
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
| | - Bernina Naissant
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- Laboratoire de Biologie de la Transmission de Plasmodium, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
| | - Eloise Thompson
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Florence Breil
- Institut Pasteur, Unité de Génétique et Génomique des Insectes Vecteurs, CNRS URA 3012, Paris, France
| | - Audrey Lorthiois
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- Laboratoire de Biologie de la Transmission de Plasmodium, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
- Institut Pasteur, Unité de Génétique et Génomique des Insectes Vecteurs, CNRS URA 3012, Paris, France
| | - Florian Dupuy
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- Laboratoire de Biologie de la Transmission de Plasmodium, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
| | - Ross Cummings
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Yoann Duffier
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- Laboratoire de Biologie de la Transmission de Plasmodium, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
| | - Yolanda Corbett
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università di Milano, Milano, Italy
| | | | - Kenneth Vernick
- Institut Pasteur, Unité de Génétique et Génomique des Insectes Vecteurs, CNRS URA 3012, Paris, France
| | - Donatella Taramelli
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Università di Milano, Milano, Italy
| | - David A. Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Gordon Langsley
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- * E-mail: (GL); (CL)
| | - Catherine Lavazec
- Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
- Laboratoire de Biologie de la Transmission de Plasmodium, Faculté de Médicine, Université Paris Descartes—Sorbonne Paris Cité, Paris, France
- Institut Pasteur, Unité de Génétique et Génomique des Insectes Vecteurs, CNRS URA 3012, Paris, France
- * E-mail: (GL); (CL)
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97
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Thavayogarajah T, Gangopadhyay P, Rahlfs S, Becker K, Lingelbach K, Przyborski JM, Holder AA. Alternative Protein Secretion in the Malaria Parasite Plasmodium falciparum. PLoS One 2015; 10:e0125191. [PMID: 25909331 PMCID: PMC4409355 DOI: 10.1371/journal.pone.0125191] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/11/2015] [Indexed: 12/13/2022] Open
Abstract
Plasmodium falciparum invades human red blood cells, residing in a parasitophorous vacuole (PV), with a parasitophorous vacuole membrane (PVM) separating the PV from the host cell cytoplasm. Here we have investigated the role of N-myristoylation and two other N-terminal motifs, a cysteine potential S-palmitoylation site and a stretch of basic residues, as the driving force for protein targeting to the parasite plasma membrane (PPM) and subsequent translocation across this membrane. Plasmodium falciparum adenylate kinase 2 (Pf AK2) contains these three motifs, and was previously proposed to be targeted beyond the parasite to the PVM, despite the absence of a signal peptide for entry into the classical secretory pathway. Biochemical and microscopy analyses of PfAK2 variants tagged with green fluorescent protein (GFP) showed that these three motifs are involved in targeting the protein to the PPM and translocation across the PPM to the PV. It was shown that the N-terminal 37 amino acids of PfAK2 alone are sufficient to target and translocate GFP across the PPM. As a control we examined the N-myristoylated P. falciparum ADP-ribosylation factor 1 (PfARF1). PfARF1 was found to co-localise with a Golgi marker. To determine whether or not the putative palmitoylation and the cluster of lysine residues from the N-terminus of PfAK2 would modulate the subcellular localization of PfARF1, a chimeric fusion protein containing the N-terminus of PfARF1 and the two additional PfAK2 motifs was analysed. This chimeric protein was targeted to the PPM, but not translocated across the membrane into the PV, indicating that other features of the N-terminus of PfAK2 also play a role in the secretion process.
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Affiliation(s)
- Thuvaraka Thavayogarajah
- Division of Parasitology, Faculty of Biology, Philipps-University Marburg, Karl-von-Frisch Straße 8, 35043 Marburg, Germany
| | - Preetish Gangopadhyay
- Division of Parasitology, Faculty of Biology, Philipps-University Marburg, Karl-von-Frisch Straße 8, 35043 Marburg, Germany
| | - Stefan Rahlfs
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Klaus Lingelbach
- Division of Parasitology, Faculty of Biology, Philipps-University Marburg, Karl-von-Frisch Straße 8, 35043 Marburg, Germany
| | - Jude M. Przyborski
- Division of Parasitology, Faculty of Biology, Philipps-University Marburg, Karl-von-Frisch Straße 8, 35043 Marburg, Germany
- * E-mail: (AAH); (JMP)
| | - Anthony A. Holder
- The Francis Crick Institute Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
- * E-mail: (AAH); (JMP)
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98
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Dent AE, Nakajima R, Liang L, Baum E, Moormann AM, Sumba PO, Vulule J, Babineau D, Randall A, Davies DH, Felgner PL, Kazura JW. Plasmodium falciparum Protein Microarray Antibody Profiles Correlate With Protection From Symptomatic Malaria in Kenya. J Infect Dis 2015; 212:1429-38. [PMID: 25883384 DOI: 10.1093/infdis/jiv224] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/25/2015] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Immunoglobulin G antibodies (Abs) to Plasmodium falciparum antigens have been associated with naturally acquired immunity to symptomatic malaria. METHODS We probed protein microarrays covering 824 unique P. falciparum protein features with plasma from residents of a community in Kenya monitored for 12 weeks for (re)infection and symptomatic malaria after administration of antimalarial drugs. P. falciparum proteins recognized by Abs from 88 children (aged 1-14 years) and 86 adults (aged ≥ 18 years), measured at the beginning of the observation period, were ranked by Ab signal intensity. RESULTS Abs from immune adults reacted with a total 163 of 824 P. falciparum proteins. Children gradually acquired Abs to the full repertoire of antigens recognized by adults. Abs to some antigens showed high seroconversion rates, reaching maximal levels early in childhood, whereas others did not reach adult levels until adolescence. No correlation between Ab signal intensity and time to (re)infection was observed. In contrast, Ab levels to 106 antigens were significantly higher in children who were protected from symptomatic malaria compared with those who were not. Abs to antigens predictive of protection included P. falciparum erythrocyte membrane protein 1, merozoite surface protein (MSP) 10, MSP2, liver-stage antigen 3, PF70, MSP7, and Plasmodium helical interspersed subtelomeric domain protein. CONCLUSIONS Protein microarrays may be useful in the search for malaria antigens associated with protective immunity.
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Affiliation(s)
- Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University Rainbow Babies and Children's Hospital, Cleveland, Ohio
| | | | - Li Liang
- University of California, Irvine
| | | | - Ann M Moormann
- Center for Global Health Research, University of Massachusetts Medical School, Worcester
| | | | | | | | | | | | | | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University
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99
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Tarr SJ, Osborne AR. Experimental determination of the membrane topology of the Plasmodium protease Plasmepsin V. PLoS One 2015; 10:e0121786. [PMID: 25849462 PMCID: PMC4388684 DOI: 10.1371/journal.pone.0121786] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 02/07/2015] [Indexed: 11/23/2022] Open
Abstract
The malaria parasite exports hundreds of proteins into its host cell. The majority of exported proteins contain a Host-Targeting motif (also known as a Plasmodium export element) that directs them for export. Prior to export, the Host-Targeting motif is cleaved by the endoplasmic reticulum-resident protease Plasmepsin V and the newly generated N-terminus is N-α-acetylated by an unidentified enzyme. The cleaved, N-α-acetylated protein is trafficked to the parasitophorous vacuole, where it is translocated across the vacuole membrane. It is clear that cleavage and N-α-acetylation of the Host-Targeting motif occur at the endoplasmic reticulum, and it has been proposed that Host-Targeting motif cleavage and N-α-acetylation occur either on the luminal or cytosolic side of the endoplasmic reticulum membrane. Here, we use self-associating ‘split’ fragments of GFP to determine the topology of Plasmepsin V in the endoplasmic reticulum membrane; we show that the catalytic protease domain of Plasmepsin V faces the endoplasmic reticulum lumen. These data support a model in which the Host-Targeting motif is cleaved and N-α-acetylated in the endoplasmic reticulum lumen. Furthermore, these findings suggest that cytosolic N-α-acetyltransferases are unlikely to be candidates for the N-α-acetyltransferase of Host-Targeting motif-containing exported proteins.
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Affiliation(s)
- Sarah J. Tarr
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, United Kingdom
| | - Andrew R. Osborne
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, United Kingdom
- * E-mail:
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In Vivo Function of PTEX88 in Malaria Parasite Sequestration and Virulence. EUKARYOTIC CELL 2015; 14:528-34. [PMID: 25820521 DOI: 10.1128/ec.00276-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/25/2015] [Indexed: 01/07/2023]
Abstract
Malaria pathology is linked to remodeling of red blood cells by eukaryotic Plasmodium parasites. Central to host cell refurbishment is the trafficking of parasite-encoded virulence factors through the Plasmodium translocon of exported proteins (PTEX). Much of our understanding of its function is based on experimental work with cultured Plasmodium falciparum, yet direct consequences of PTEX impairment during an infection remain poorly defined. Using the murine malaria model parasite Plasmodium berghei, it is shown here that efficient sequestration to the pulmonary, adipose, and brain tissue vasculature is dependent on the PTEX components thioredoxin 2 (TRX2) and PTEX88. While TRX2-deficient parasites remain virulent, PTEX88-deficient parasites no longer sequester in the brain, correlating with abolishment of cerebral complications in infected mice. However, an apparent trade-off for virulence attenuation was spleen enlargement, which correlates with a strongly reduced schizont-to-ring-stage transition. Strikingly, general protein export is unaffected in PTEX88-deficient mutants that mature normally in vitro. Thus, PTEX88 is pivotal for tissue sequestration in vivo, parasite virulence, and preventing exacerbation of spleen pathology, but these functions do not correlate with general protein export to the host erythrocyte. The presented data suggest that the protein export machinery of Plasmodium parasites and their underlying mechanistic features are considerably more complex than previously anticipated and indicate challenges for targeted intervention strategies.
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