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Fraser M, Curtis B, Phillips P, Yates PA, Lam KS, Netzel O, van Dooren GG, Ingmundson A, Matuschewski K, McLeod MD, Maier AG. Harnessing cholesterol uptake of malaria parasites for therapeutic applications. EMBO Mol Med 2024; 16:1515-1532. [PMID: 38862600 PMCID: PMC11251039 DOI: 10.1038/s44321-024-00087-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 05/14/2024] [Accepted: 05/24/2024] [Indexed: 06/13/2024] Open
Abstract
Parasites, such as the malaria parasite P. falciparum, are critically dependent on host nutrients. Interference with nutrient uptake can lead to parasite death and, therefore, serve as a successful treatment strategy. P. falciparum parasites cannot synthesise cholesterol, and instead source this lipid from the host. Here, we tested whether cholesterol uptake pathways could be 'hijacked' for optimal drug delivery to the intracellular parasite. We found that fluorescent cholesterol analogues were delivered from the extracellular environment to the intracellular parasite. We investigated the uptake and inhibitory effects of conjugate compounds, where proven antimalarial drugs (primaquine and artesunate) were attached to steroids that mimic the structure of cholesterol. These conjugated antimalarial drugs improved the inhibitory effects against multiple parasite lifecycle stages, multiple parasite species, and drug-resistant parasites, whilst also lowering the toxicity to human host cells. Steroids with introduced peroxides also displayed antimalarial activity. These results provide a proof-of-concept that cholesterol mimics can be developed as a drug delivery system against apicomplexan parasites with the potential to improve drug efficacy, increase therapeutic index, and defeat drug resistance.
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Affiliation(s)
- Merryn Fraser
- Research School of Biology, The Australian National University, Canberra, 2601, Australia
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, 10115, Germany
- Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, 02115, USA
| | - Blake Curtis
- Research School of Chemistry, The Australian National University, Canberra, 2601, Australia
- Metabolism of Microbial Pathogens, Robert Koch Institute, Berlin, 13353, Germany
| | - Patrick Phillips
- Research School of Biology, The Australian National University, Canberra, 2601, Australia
| | - Patrick A Yates
- Research School of Chemistry, The Australian National University, Canberra, 2601, Australia
| | - Kwong Sum Lam
- Research School of Biology, The Australian National University, Canberra, 2601, Australia
| | - Otto Netzel
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, 10115, Germany
| | - Giel G van Dooren
- Research School of Biology, The Australian National University, Canberra, 2601, Australia
| | - Alyssa Ingmundson
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, 10115, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, 10115, Germany
| | - Malcolm D McLeod
- Research School of Chemistry, The Australian National University, Canberra, 2601, Australia.
| | - Alexander G Maier
- Research School of Biology, The Australian National University, Canberra, 2601, Australia.
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2
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Wiser MF. Knobs, Adhesion, and Severe Falciparum Malaria. Trop Med Infect Dis 2023; 8:353. [PMID: 37505649 PMCID: PMC10385726 DOI: 10.3390/tropicalmed8070353] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/30/2023] [Accepted: 07/02/2023] [Indexed: 07/29/2023] Open
Abstract
Plasmodium falciparum can cause a severe disease with high mortality. A major factor contributing to the increased virulence of P. falciparum, as compared to other human malarial parasites, is the sequestration of infected erythrocytes in the capillary beds of organs and tissues. This sequestration is due to the cytoadherence of infected erythrocytes to endothelial cells. Cytoadherence is primarily mediated by a parasite protein expressed on the surface of the infected erythrocyte called P. falciparum erythrocyte membrane protein-1 (PfEMP1). PfEMP1 is embedded in electron-dense protuberances on the surface of the infected erythrocytes called knobs. These knobs are assembled on the erythrocyte membrane via exported parasite proteins, and the knobs function as focal points for the cytoadherence of infected erythrocytes to endothelial cells. PfEMP1 is a member of the var gene family, and there are approximately 60 antigenically distinct PfEMP1 alleles per parasite genome. Var gene expression exhibits allelic exclusion, with only a single allele being expressed by an individual parasite. This results in sequential waves of antigenically distinct infected erythrocytes and this antigenic variation allows the parasite to establish long-term chronic infections. A wide range of endothelial cell receptors can bind to the various PfEMP1 alleles, and thus, antigenic variation also results in a change in the cytoadherence phenotype. The cytoadherence phenotype may result in infected erythrocytes sequestering in different tissues and this difference in sequestration may explain the wide range of possible clinical manifestations associated with severe falciparum malaria.
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Affiliation(s)
- Mark F Wiser
- Department of Tropical Medicine and Infectious Disease, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, New Orleans, LA 70112, USA
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3
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Maier AG, van Ooij C. The role of cholesterol in invasion and growth of malaria parasites. Front Cell Infect Microbiol 2022; 12:984049. [PMID: 36189362 PMCID: PMC9522969 DOI: 10.3389/fcimb.2022.984049] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/15/2022] [Indexed: 11/24/2022] Open
Abstract
Malaria parasites are unicellular eukaryotic pathogens that develop through a complex lifecycle involving two hosts, an anopheline mosquito and a vertebrate host. Throughout this lifecycle, the parasite encounters widely differing conditions and survives in distinct ways, from an intracellular lifestyle in the vertebrate host to exclusively extracellular stages in the mosquito. Although the parasite relies on cholesterol for its growth, the parasite has an ambiguous relationship with cholesterol: cholesterol is required for invasion of host cells by the parasite, including hepatocytes and erythrocytes, and for the development of the parasites in those cells. However, the parasite is unable to produce cholesterol itself and appears to remove cholesterol actively from its own plasma membrane, thereby setting up a cholesterol gradient inside the infected host erythrocyte. Overall a picture emerges in which the parasite relies on host cholesterol and carefully controls its transport. Here, we describe the role of cholesterol at the different lifecycle stages of the parasites.
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Affiliation(s)
- Alexander G. Maier
- Research School of Biology, The Australian National University, Canberra ACT, Australia
- *Correspondence: Alexander G. Maier, ; Christiaan van Ooij,
| | - Christiaan van Ooij
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- *Correspondence: Alexander G. Maier, ; Christiaan van Ooij,
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Deletion of the Plasmodium falciparum exported protein PTP7 leads to Maurer’s clefts vesiculation, host cell remodeling defects, and loss of surface presentation of EMP1. PLoS Pathog 2022; 18:e1009882. [PMID: 35930605 PMCID: PMC9385048 DOI: 10.1371/journal.ppat.1009882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/17/2022] [Accepted: 06/19/2022] [Indexed: 11/19/2022] Open
Abstract
Presentation of the variant antigen, Plasmodium falciparum erythrocyte membrane protein 1 (EMP1), at knob-like protrusions on the surface of infected red blood cells, underpins the parasite’s pathogenicity. Here we describe a protein PF3D7_0301700 (PTP7), that functions at the nexus between the intermediate trafficking organelle, the Maurer’s cleft, and the infected red blood cell surface. Genetic disruption of PTP7 leads to accumulation of vesicles at the Maurer’s clefts, grossly aberrant knob morphology, and failure to deliver EMP1 to the red blood cell surface. We show that an expanded low complexity sequence in the C-terminal region of PTP7, identified only in the Laverania clade of Plasmodium, is critical for efficient virulence protein trafficking. We describe a malaria parasite protein, PTP7, involved in virulence factor trafficking that is associated with Maurer’s clefts and other trafficking compartments. Upon disruption of the PTP7 locus, the Maurer’s clefts become decorated with vesicles; the knobby protrusions on the host red blood cell surface are fewer and distorted; and trafficking of the virulence protein, EMP1, to the host red blood cell surface is ablated. We provide evidence that a region of PTP7 with low sequence complexity plays an important role in virulence protein trafficking from the Maurer’s clefts.
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A Phosphoinositide-Binding Protein Acts in the Trafficking Pathway of Hemoglobin in the Malaria Parasite Plasmodium falciparum. mBio 2022; 13:e0323921. [PMID: 35038916 PMCID: PMC8764524 DOI: 10.1128/mbio.03239-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Phosphoinositide lipids play key roles in a variety of processes in eukaryotic cells, but our understanding of their functions in the malaria parasite Plasmodium falciparum is still very much limited. To gain a deeper comprehension of the roles of phosphoinositides in this important pathogen, we attempted gene inactivation for 24 putative effectors of phosphoinositide metabolism. Our results reveal that 79% of the candidates are refractory to genetic deletion and are therefore potentially essential for parasite growth. Inactivation of the gene coding for a Plasmodium-specific putative phosphoinositide-binding protein, which we named PfPX1, results in a severe growth defect. We show that PfPX1 likely binds phosphatidylinositol-3-phosphate and that it localizes to the membrane of the digestive vacuole of the parasite and to vesicles filled with host cell cytosol and labeled with endocytic markers. Critically, we provide evidence that it is important in the trafficking pathway of hemoglobin from the host erythrocyte to the digestive vacuole. Finally, inactivation of PfPX1 renders parasites resistant to artemisinin, the frontline antimalarial drug. Globally, the minimal redundancy in the putative phosphoinositide proteins uncovered in our work supports that targeting this pathway has potential for antimalarial drug development. Moreover, our identification of a phosphoinositide-binding protein critical for the trafficking of hemoglobin provides key insight into this essential process. IMPORTANCE Malaria represents an enormous burden for a significant proportion of humanity, and the lack of vaccines and problems with drug resistance to all antimalarials demonstrate the need to develop new therapeutics. Inhibitors of phosphoinositide metabolism are currently being developed as antimalarials but our understanding of this biological pathway is incomplete. The malaria parasite lives inside human red blood cells where it imports hemoglobin to cover some of its nutritional needs. In this work, we have identified a phosphoinositide-binding protein that is important for the transport of hemoglobin in the parasite. Inactivation of this protein decreases the ability of the parasite to proliferate. Our results have therefore identified a potential new target for antimalarial development.
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Lee WC, Russell B, Lee B, Chu CS, Phyo AP, Sriprawat K, Lau YL, Nosten F, Rénia L. Plasmodium falciparum rosetting protects schizonts against artemisinin. EBioMedicine 2021; 73:103680. [PMID: 34749300 PMCID: PMC8586750 DOI: 10.1016/j.ebiom.2021.103680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/04/2021] [Accepted: 10/25/2021] [Indexed: 11/24/2022] Open
Abstract
Background Artemisinin (ART) resistance in Plasmodium falciparum is thought to occur during the early stage of the parasite's erythrocytic cycle. Here, we identify a novel factor associated with the late stage parasite development that contributes to ART resistance. Methods Rosetting rates of clinical isolates pre- and post- brief (one hour) exposure to artesunate (AS, an ART derivative) were evaluated. The effects of AS-mediated rosetting on the post-AS-exposed parasite's replication and survival, as well as the extent of protection by AS-mediated rosetting on different parasite stages were investigated. The rosetting ligands, mechanisms, and gene mutations involved were studied. Findings Brief AS exposure stimulated rosetting, with AS-resistant isolates forming more rosettes in a more rapid manner. AS-mediated rosetting enabled infected erythrocytes (IRBC) to withstand AS exposure for several hours and protected the IRBC from phagocytosis. When their rosetting ability was blocked experimentally, the post-AS exposure survival advantage by the AS-resistant parasites was abrogated. Deletions in two genes coding for PfEMP1 exon 2 (PF3D7_0200300 and PF3D7_0223300) were found to be associated with AS-mediated rosetting, and these mutations were significantly selected through time in the parasite population under study, along with the K13 mutations, a molecular marker of ART-resistance. Interpretation Rapid ART parasite clearance is driven by the direct oxidative damages on IRBC by ART and the phagocytic destruction of the damaged IRBC. Rosetting serves as a rapid ‘buying time’ strategy that allows more parasites to complete schizont maturation, reinvasion and subsequent development into the intrinsically less ART-susceptible ring stage. Funding A*STAR, NMRC-OF-YIRG, HRC e-ASIA, Wellcome.
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Affiliation(s)
- Wenn-Chyau Lee
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore; Singapore Immunology Network (SIgN), A*STAR, Singapore.
| | - Bruce Russell
- Department of Microbiology and Immunology, University of Otago, Dunedin, Otago, New Zealand
| | - Bernett Lee
- Singapore Immunology Network (SIgN), A*STAR, Singapore
| | - Cindy S Chu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand; Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand; Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Kanlaya Sriprawat
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand
| | - Yee-Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand; Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Laurent Rénia
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore; Singapore Immunology Network (SIgN), A*STAR, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore.
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Creative interior design by Plasmodium falciparum: Lipid metabolism and the parasite's secret chamber. Parasitol Int 2021; 83:102369. [PMID: 33905815 DOI: 10.1016/j.parint.2021.102369] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/06/2021] [Accepted: 04/20/2021] [Indexed: 11/21/2022]
Abstract
Malaria parasites conceal themselves within host erythrocytes and establish a necessary logistics system through the three-membrane layered structures of these cells. To establish this system, lipid metabolism is needed for the de novo synthesis of lipids and the recycling of extracellular lipids and erythrocyte lipid components. Cholesterol supply depends on its uptake from the extracellular environment and erythrocyte cytoplasm, but phospholipids can be synthesized on their own. This differential production of lipid species creates unique modifications in the lipid profile of parasitized erythrocytes, which in turn may influence the biophysical and/or mechanical properties of organelles and vesicles and communication among them. Variations in local membrane properties possibly influence the transportation of various molecules such as parasite-derived proteins, because efficiencies in secretion, vesicle fusion and budding are partly determined by the lipid profiles. Comprehensive understanding of the parasite's lipid metabolism and the biophysics of lipid membranes provides fundamental knowledge about these pathogenic organisms and could lead to new anti-malarials.
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8
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Govindarajalu G, Rizvi Z, Kumar D, Sijwali PS. Lyse-Reseal Erythrocytes for Transfection of Plasmodium falciparum. Sci Rep 2019; 9:19952. [PMID: 31882761 PMCID: PMC6934678 DOI: 10.1038/s41598-019-56513-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/13/2019] [Indexed: 01/09/2023] Open
Abstract
Simple and efficient transfection methods for genetic manipulation of Plasmodium falciparum are desirable to identify, characterize and validate the genes with therapeutic potential and better understand parasite biology. Among the available transfection techniques for P. falciparum, electroporation-based methods, particularly electroporation of ring-infected RBCs is routinely used. Nonetheless, transfection of P. falciparum remains a resource-intensive procedure. Here, we report a simple and economic transfection method for P. falciparum, which is termed as the lyse-reseal erythrocytes for transfection (LyRET). It involved lysis of erythrocytes with a hypotonic RBC lysis buffer containing the desired plasmid DNA, followed by resealing by adding a high salt buffer. These DNA-encapsulated lyse-reseal erythrocytes were mixed with P. falciparum trophozoite/schizont stages and subjected to selection for the plasmid-encoded drug resistance. In parallel, transfections were also done by the methods utilizing electroporation of DNA into uninfected RBCs and parasite-infected RBCs. The LyRET method successfully transfected 3D7 and D10 strains with different plasmids in 63 of the 65 attempts, with success rate similar to transfection by electroporation of DNA into infected RBCs. The cost effectiveness and comparable efficiency of LyRET method makes it an alternative to the existing transfection methods for P. falciparum, particularly in resource-limited settings.
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Affiliation(s)
| | - Zeba Rizvi
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, TS, India
| | - Deepak Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, TS, India
| | - Puran Singh Sijwali
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, TS, India.
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9
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Kennedy K, Cobbold SA, Hanssen E, Birnbaum J, Spillman NJ, McHugh E, Brown H, Tilley L, Spielmann T, McConville MJ, Ralph SA. Delayed death in the malaria parasite Plasmodium falciparum is caused by disruption of prenylation-dependent intracellular trafficking. PLoS Biol 2019; 17:e3000376. [PMID: 31318858 PMCID: PMC6667170 DOI: 10.1371/journal.pbio.3000376] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 07/30/2019] [Accepted: 07/01/2019] [Indexed: 02/07/2023] Open
Abstract
Apicomplexan parasites possess a plastid organelle called the apicoplast. Inhibitors that selectively target apicoplast housekeeping functions, including DNA replication and protein translation, are lethal for the parasite, and several (doxycycline, clindamycin, and azithromycin) are in clinical use as antimalarials. A major limitation of such drugs is that treated parasites only arrest one intraerythrocytic development cycle (approximately 48 hours) after treatment commences, a phenotype known as the ‘delayed death’ effect. The molecular basis of delayed death is a long-standing mystery in parasitology, and establishing the mechanism would aid rational clinical implementation of apicoplast-targeted drugs. Parasites undergoing delayed death transmit defective apicoplasts to their daughter cells and cannot produce the sole, blood-stage essential metabolic product of the apicoplast: the isoprenoid precursor isopentenyl-pyrophosphate. How the isoprenoid precursor depletion kills the parasite remains unknown. We investigated the requirements for the range of isoprenoids in the human malaria parasite Plasmodium falciparum and characterised the molecular and morphological phenotype of parasites experiencing delayed death. Metabolomic profiling reveals disruption of digestive vacuole function in the absence of apicoplast derived isoprenoids. Three-dimensional electron microscopy reveals digestive vacuole fragmentation and the accumulation of cytostomal invaginations, characteristics common in digestive vacuole disruption. We show that digestive vacuole disruption results from a defect in the trafficking of vesicles to the digestive vacuole. The loss of prenylation of vesicular trafficking proteins abrogates their membrane attachment and function and prevents the parasite from feeding. Our data show that the proximate cause of delayed death is an interruption of protein prenylation and consequent cellular trafficking defects. After treatment with drugs that target apicoplast functions, malaria parasites are initially superficially healthy and go on to infect new erythrocytes. This cell biology study shows that the parasites subsequently die in their second cycle due to trafficking defects caused by depletion of prenyl groups.
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Affiliation(s)
- Kit Kennedy
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Simon A. Cobbold
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Eric Hanssen
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
- Advanced Microscopy Facility, Bio21 Molecular Science and Biotechnology Institute, Victoria, Australia
| | - Jakob Birnbaum
- Molecular Biology and Immunology Section, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Natalie J. Spillman
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Emma McHugh
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Hannah Brown
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Tobias Spielmann
- Molecular Biology and Immunology Section, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - Stuart A. Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
- * E-mail:
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Raphemot R, Toro-Moreno M, Lu KY, Posfai D, Derbyshire ER. Discovery of Druggable Host Factors Critical to Plasmodium Liver-Stage Infection. Cell Chem Biol 2019; 26:1253-1262.e5. [PMID: 31257182 DOI: 10.1016/j.chembiol.2019.05.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/06/2019] [Accepted: 05/22/2019] [Indexed: 11/26/2022]
Abstract
Plasmodium parasites undergo an obligatory and asymptomatic developmental stage within the liver before infecting red blood cells to cause malaria. The hijacked host pathways critical to parasite infection during this hepatic phase remain poorly understood. Here, we implemented a forward genetic screen to identify over 100 host factors within the human druggable genome that are critical to P. berghei infection in hepatoma cells. Notably, we found knockdown of genes involved in protein trafficking pathways to be detrimental to parasite infection. The disruption of protein trafficking modulators, including COPB2 and GGA1, decreases P. berghei parasite size, and an immunofluorescence study suggests that these proteins are recruited to the Plasmodium parasitophorous vacuole in infected hepatocytes. These findings reveal that various host intracellular protein trafficking pathways are subverted by Plasmodium parasites during the liver stage and provide new insights into their manipulation for growth and development.
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Affiliation(s)
- Rene Raphemot
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708, USA
| | - Maria Toro-Moreno
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708, USA
| | - Kuan-Yi Lu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, NC 27710, USA
| | - Dora Posfai
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, NC 27710, USA
| | - Emily Rose Derbyshire
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708, USA; Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, NC 27710, USA.
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11
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Behl A, Kumar V, Bisht A, Panda JJ, Hora R, Mishra PC. Cholesterol bound Plasmodium falciparum co-chaperone 'PFA0660w' complexes with major virulence factor 'PfEMP1' via chaperone 'PfHsp70-x'. Sci Rep 2019; 9:2664. [PMID: 30804381 PMCID: PMC6389991 DOI: 10.1038/s41598-019-39217-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 12/20/2018] [Indexed: 01/31/2023] Open
Abstract
Lethality of Plasmodium falciparum caused malaria results from ‘cytoadherence’, which is mainly effected by exported Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. Several exported P. falciparum proteins (exportome) including chaperones alongside cholesterol rich microdomains are crucial for PfEMP1 translocation to infected erythrocyte surface. An exported Hsp40 (heat shock protein 40) ‘PFA0660w’ functions as a co-chaperone of ‘PfHsp70-x’, and these co-localize to specialized intracellular mobile structures termed J-dots. Our studies attempt to understand the function of PFA0660w-PfHsp70-x chaperone pair using recombinant proteins. Biochemical assays reveal that N and C-terminal domains of PFA0660w and PfHsp70-x respectively are critical for their activity. We show the novel direct interaction of PfHsp70-x with the cytoplasmic tail of PfEMP1, and binding of PFA0660w with cholesterol. PFA0660w operates both as a chaperone and lipid binding molecule via its separate substrate and cholesterol binding sites. PfHsp70-x interacts with cholesterol bound PFA0660w and PfEMP1 simultaneously in vitro to form a complex. Collectively, our results and the past literature support the hypothesis that PFA0660w-PfHsp70-x chaperone pair assists PfEMP1 transport across the host erythrocyte through cholesterol containing ‘J-dots’. These findings further the understanding of PfEMP1 export in malaria parasites, though their in vivo validation remains to be performed.
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Affiliation(s)
- Ankita Behl
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Vikash Kumar
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Anjali Bisht
- Institute of Nano Science and Technology, Mohali, India
| | - Jiban J Panda
- Institute of Nano Science and Technology, Mohali, India
| | - Rachna Hora
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
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PfVPS45 Is Required for Host Cell Cytosol Uptake by Malaria Blood Stage Parasites. Cell Host Microbe 2019; 25:166-173.e5. [DOI: 10.1016/j.chom.2018.11.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 10/01/2018] [Accepted: 11/19/2018] [Indexed: 12/12/2022]
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13
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Mudududdla R, Mohanakrishnan D, Bharate SS, Vishwakarma RA, Sahal D, Bharate SB. Orally Effective Aminoalkyl 10H-Indolo[3,2-b]quinoline-11-carboxamide Kills the Malaria Parasite by Inhibiting Host Hemoglobin Uptake. ChemMedChem 2018; 13:2581-2598. [PMID: 30358112 DOI: 10.1002/cmdc.201800579] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/10/2018] [Indexed: 12/26/2022]
Abstract
A series of indolo[3,2-b]quinoline-C11-carboxamides were synthesized by incorporation of aminoalkyl side chains into the core of indolo[3,2-b]quinoline-C11-carboxylic acid. Their in vitro antiplasmodial evaluation against Plasmodium falciparum led to the identification of a 2-(piperidin-1-yl)ethanamine-linked analogue {2-bromo-N-[2-(piperidin-1-yl)ethyl]-10H-indolo[3,2-b]quinoline-11-carboxamide (3 g)} (IC50 =1.3 μm) as the most promising compound exhibiting good selectivity indices against mammalian cell lines. The kill kinetics on erythrocytic-stage parasites revealed that 3 g caused complete killing of only the trophozoite-stage parasites. Mechanistic studies showed that 3 g targets the food vacuole of the parasite and inhibits hemoglobin uptake, β-hematin formation, and the basic endocytic processes of the parasite. Analogue 3 g was found to be orally bioavailable, and its curative antimalarial studies at 50 mg per kg p.o. against a Plasmodium berghei (ANKA)-infected mouse model revealed that mice treated with 3 g showed 27-35 % suppression of parasitemia with an increase in life span relative to untreated, control mice. Thus, the present work demonstrated a proof of concept for the oral efficacy of indolo[3,2-b]quinoline-C11-carboxamides.
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Affiliation(s)
- Ramesh Mudududdla
- CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Dinesh Mohanakrishnan
- Malaria Drug Discovery Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Sonali S Bharate
- CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Ram A Vishwakarma
- CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Dinkar Sahal
- Malaria Drug Discovery Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Sandip B Bharate
- CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
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14
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Arama C, Diarra I, Kouriba B, Sirois F, Fedoryak O, Thera MA, Coulibaly D, Lyke KE, Plowe CV, Chrétien M, Doumbo OK, Mbikay M. Malaria severity: Possible influence of the E670G PCSK9 polymorphism: A preliminary case-control study in Malian children. PLoS One 2018; 13:e0192850. [PMID: 29447211 PMCID: PMC5813955 DOI: 10.1371/journal.pone.0192850] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/31/2018] [Indexed: 11/19/2022] Open
Abstract
Aim Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) is a hepatic secretory protein which promotes the degradation of low-density lipoprotein receptors leading to reduced hepatic uptake of plasma cholesterol. Non-synonymous single-nucleotide polymorphisms in its gene have been linked to hypo- or hyper- cholesterolemia, depending on whether they decrease or increase PCSK9 activity, respectively. Since the proliferation and the infectivity of Plasmodium spp. partially depend on cholesterol from the host, we hypothesize that these PCSK9 genetic polymorphisms could influence the course of malaria infection in individuals who carry them. Here we examined the frequency distribution of one dominant (C679X) and two recessive (A443T, I474V) hypocholesterolemic polymorphisms as well as that of one recessive hypercholesterolemic polymorphism (E670G) among healthy and malaria-infected Malian children. Methods Dried blood spots were collected in Bandiagara, Mali, from 752 age, residence and ethnicity-matched children: 253 healthy controls, 246 uncomplicated malaria patients and 253 severe malaria patients. Their genomic DNA was extracted and genotyped for the above PCSK9 polymorphisms using Taqman assays. Associations of genotype distributions and allele frequencies with malaria were evaluated. Results The minor allele frequency of the A443T, I474V, E670G, and C679X polymorphisms in the study population sample was 0.12, 0.20, 0.26, and 0.02, respectively. For each polymorphism, the genotype distribution among the three health conditions was statistically insignificant, but for the hypercholesterolemic E670G polymorphism, a trend towards association of the minor allele with malaria severity was observed (P = 0.035). The association proved to be stronger when allele frequencies between healthy controls and severe malaria cases were compared (Odd Ratio: 1.34; 95% Confidence Intervals: 1.04–1.83); P = 0.031). Conclusions Carriers of the minor allele of the E670G PCSK9 polymorphism might be more susceptible to severe malaria. Further investigation of the cholesterol regulating function of PCSK9 in the pathophysiology of malaria is needed.
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Affiliation(s)
- Charles Arama
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Issa Diarra
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Bourèma Kouriba
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Francine Sirois
- Laboratoire de protéolyse fonctionnelle, Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | - Olesya Fedoryak
- Laboratoire de protéolyse fonctionnelle, Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | - Mahamadou A. Thera
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Drissa Coulibaly
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
| | - Kirsten E. Lyke
- Center for Vaccine Development and Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Christopher V. Plowe
- Center for Vaccine Development and Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Michel Chrétien
- Laboratoire de protéolyse fonctionnelle, Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
- Chronic Disease Program, Ottawa Hospital Research Hospital, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, International Centers for Excellence in Research, Université des Sciences, des Techniques et des Technologies de Bamako, Bamako, Mali
- * E-mail: (MM); (OKD)
| | - Majambu Mbikay
- Laboratoire de protéolyse fonctionnelle, Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
- Chronic Disease Program, Ottawa Hospital Research Hospital, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- * E-mail: (MM); (OKD)
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15
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Morake M, Coertzen D, Ngwane A, Wentzel JF, Wong HN, Smit FJ, Birkholtz LM, Pietersen RD, Baker B, Wiid I, N'Da DD, Haynes RK. Preliminary Evaluation of Artemisinin-Cholesterol Conjugates as Potential Drugs for the Treatment of Intractable Forms of Malaria and Tuberculosis. ChemMedChem 2017; 13:67-77. [DOI: 10.1002/cmdc.201700579] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 11/22/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Mokhitli Morake
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
| | - Dina Coertzen
- Department of Biochemistry, Centre for Sustainable Malaria Control; University of Pretoria; Private Bag X20 Hatfield 0028 South Africa
| | - Andile Ngwane
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg 7505 South Africa
| | - Johannes F. Wentzel
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
| | - Ho Ning Wong
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
| | - Frans J. Smit
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Centre for Sustainable Malaria Control; University of Pretoria; Private Bag X20 Hatfield 0028 South Africa
| | - Ray-Dean Pietersen
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg 7505 South Africa
| | - Bienyameen Baker
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg 7505 South Africa
| | - Ian Wiid
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences; Stellenbosch University; Tygerberg 7505 South Africa
| | - David D. N'Da
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
| | - Richard K. Haynes
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences; North-West University; Potchefstroom 2520 South Africa
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16
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Fratini F, Raggi C, Sferra G, Birago C, Sansone A, Grasso F, Currà C, Olivieri A, Pace T, Mochi S, Picci L, Ferreri C, Di Biase A, Pizzi E, Ponzi M. An Integrated Approach to Explore Composition and Dynamics of Cholesterol-rich Membrane Microdomains in Sexual Stages of Malaria Parasite. Mol Cell Proteomics 2017; 16:1801-1814. [PMID: 28798222 DOI: 10.1074/mcp.m117.067041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 08/04/2017] [Indexed: 12/26/2022] Open
Abstract
Membrane microdomains that include lipid rafts, are involved in key physiological and pathological processes and participate in the entry of endocellular pathogens. These assemblies, enriched in cholesterol and sphingolipids, form highly dynamic, liquid-ordered phases that can be separated from the bulk membranes thanks to their resistance to solubilization by nonionic detergents. To characterize complexity and dynamics of detergent-resistant membranes of sexual stages of the rodent malaria parasite Plasmodium berghei, here we propose an integrated study of raft components based on proteomics, lipid analysis and bioinformatics. This analysis revealed unexpected heterogeneity and unexplored pathways associated with these specialized assemblies. Protein-protein relationships and protein-lipid co-occurrence were described through multi-component networks. The proposed approach can be widely applied to virtually every cell type in different contexts and perturbations, under physiological and/or pathological conditions.
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Affiliation(s)
- Federica Fratini
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Carla Raggi
- §Istituto Superiore di Sanità, Dipartimento di Biologia Cellulare e Neuroscienze
| | - Gabriella Sferra
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Cecilia Birago
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Anna Sansone
- ¶Consiglio Nazionale delle Ricerche, I.S.O.F. - Bio Free Radicals
| | - Felicia Grasso
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Chiara Currà
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate.,From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Anna Olivieri
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Tomasino Pace
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Stefania Mochi
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Leonardo Picci
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Carla Ferreri
- ¶Consiglio Nazionale delle Ricerche, I.S.O.F. - Bio Free Radicals
| | - Antonella Di Biase
- ‖Istituto Superiore di Sanità, Dipartimento di Sanità Pubblica Veterinaria e Alimentare
| | - Elisabetta Pizzi
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate
| | - Marta Ponzi
- From the ‡Istituto Superiore di Sanità, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate;
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17
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Orikiiriza J, Surowiec I, Lindquist E, Bonde M, Magambo J, Muhinda C, Bergström S, Trygg J, Normark J. Lipid response patterns in acute phase paediatric Plasmodium falciparum malaria. Metabolomics 2017; 13:41. [PMID: 28286460 PMCID: PMC5323494 DOI: 10.1007/s11306-017-1174-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 02/03/2017] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Several studies have observed serum lipid changes during malaria infection in humans. All of them were focused at analysis of lipoproteins, not specific lipid molecules. The aim of our study was to identify novel patterns of lipid species in malaria infected patients using lipidomics profiling, to enhance diagnosis of malaria and to evaluate biochemical pathways activated during parasite infection. METHODS Using a multivariate characterization approach, 60 samples were representatively selected, 20 from each category (mild, severe and controls) of the 690 study participants between age of 0.5-6 years. Lipids from patient's plasma were extracted with chloroform/methanol mixture and subjected to lipid profiling with application of the LCMS-QTOF method. RESULTS We observed a structured plasma lipid response among the malaria-infected patients as compared to healthy controls, demonstrated by higher levels of a majority of plasma lipids with the exception of even-chain length lysophosphatidylcholines and triglycerides with lower mass and higher saturation of the fatty acid chains. An inverse lipid profile relationship was observed when plasma lipids were correlated to parasitaemia. CONCLUSIONS This study demonstrates how mapping the full physiological lipid response in plasma from malaria-infected individuals can be used to understand biochemical processes during infection. It also gives insights to how the levels of these molecules relate to acute immune responses.
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Affiliation(s)
- Judy Orikiiriza
- Infectious Diseases Institute, College of Health Sciences, Makerere University, P.O. Box 22418, Kampala, Uganda
- Department of Immunology, Institute of Molecular Medicine, Trinity College Dublin, St. James’s Hospital, Dublin, 8 Ireland
- Rwanda Military Hospital, P.O. Box: 3377, Kigali, Rwanda
| | - Izabella Surowiec
- Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | | | - Mari Bonde
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Jimmy Magambo
- Rwanda Military Hospital, P.O. Box: 3377, Kigali, Rwanda
| | - Charles Muhinda
- Rwanda Military Hospital, P.O. Box: 3377, Kigali, Rwanda
- Department of Immmunology and Microbiology, School of Biomedical Sciences College of Health Sciences, Makerere University, P.O Box 7072, Kampala, Uganda
| | - Sven Bergström
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden (MIMS), 901 87 Umeå, Sweden
- Umeå Center for Microbial Research, 901 87 Umeå, Sweden
| | - Johan Trygg
- Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Johan Normark
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
- Umeå Center for Microbial Research, 901 87 Umeå, Sweden
- Division of Infectious Diseases, Department Clinical Microbiology, Umeå University, 901 87 Umeå, Sweden
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18
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A spiral scaffold underlies cytoadherent knobs in Plasmodium falciparum-infected erythrocytes. Blood 2015; 127:343-51. [PMID: 26637786 DOI: 10.1182/blood-2015-10-674002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/30/2015] [Indexed: 12/11/2022] Open
Abstract
Much of the virulence of Plasmodium falciparum malaria is caused by cytoadherence of infected erythrocytes, which promotes parasite survival by preventing clearance in the spleen. Adherence is mediated by membrane protrusions known as knobs, whose formation depends on the parasite-derived, knob-associated histidine-rich protein (KAHRP). Knobs are required for cytoadherence under flow conditions, and they contain both KAHRP and the parasite-derived erythrocyte membrane protein PfEMP1. Using electron tomography, we have examined the 3-dimensional structure of knobs in detergent-insoluble skeletons of P falciparum 3D7 schizonts. We describe a highly organized knob skeleton composed of a spiral structure coated by an electron-dense layer underlying the knob membrane. This knob skeleton is connected by multiple links to the erythrocyte cytoskeleton. We used immuno-electron microscopy (EM) to locate KAHRP in these structures. The arrangement of membrane proteins in the knobs, visualized by high-resolution freeze-fracture scanning EM, is distinct from that in the surrounding erythrocyte membrane, with a structure at the apex that likely represents the adhesion site. Thus, erythrocyte knobs in P falciparum infection contain a highly organized skeleton structure underlying a specialized region of membrane. We propose that the spiral and dense coat organize the cytoadherence structures in the knob, and anchor them into the erythrocyte cytoskeleton. The high density of knobs and their extensive mechanical linkage suggest an explanation for the rigidification of the cytoskeleton in infected cells, and for the transmission to the cytoskeleton of shear forces experienced by adhering cells.
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19
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Bachmann A, Scholz JAM, Janßen M, Klinkert MQ, Tannich E, Bruchhaus I, Petter M. A comparative study of the localization and membrane topology of members of the RIFIN, STEVOR and PfMC-2TM protein families in Plasmodium falciparum-infected erythrocytes. Malar J 2015; 14:274. [PMID: 26173856 PMCID: PMC4502930 DOI: 10.1186/s12936-015-0784-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 06/27/2015] [Indexed: 12/12/2022] Open
Abstract
Background Variant surface antigens (VSA) exposed on the membrane of Plasmodium falciparum infected erythrocytes mediate immune evasion and are important pathogenicity factors in malaria disease. In addition to the well-studied PfEMP1, the small VSA families RIFIN, STEVOR and PfMC-2TM are assumed to play a role in this process. Methods This study presents a detailed comparative characterization of the localization, membrane topology and extraction profile across the life cycle of various members of these protein families employing confocal microscopy, immunoelectron microscopy and immunoblots. Results The presented data reveal a clear association of variants of the RIFIN, STEVOR and PfMC-2TM proteins with the host cell membrane and topological studies indicate that the semi-conserved N-terminal region of RIFINs and some STEVOR proteins is exposed at the erythrocyte surface. At the Maurer’s clefts, the semi-conserved N-terminal region as well as the variable stretch of RIFINs appears to point to the lumen away from the erythrocyte cytoplasm. These results challenge the previously proposed two transmembrane topology model for the RIFIN and STEVOR protein families and suggest that only one hydrophobic region spans the membrane. In contrast, PfMC-2TM proteins indeed seem to be anchored by two hydrophobic stretches in the host cell membrane exposing just a few, variable amino acids at the surface of the host cell. Conclusion Together, the host cell surface exposure and topology of RIFIN and STEVOR proteins suggests members of these protein families may indeed be involved in immune evasion of the infected erythrocyte, whereas members of the PfMC-2TM family seem to bear different functions in parasite biology. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0784-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna Bachmann
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Judith Anna Marie Scholz
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Marthe Janßen
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany. .,CRTD/DFG-Center for Regenerative Therapies Dresden, Technical University Dresden, Fetscherstraße 105, 01307, Dresden, Germany.
| | - Mo-Quen Klinkert
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Egbert Tannich
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Iris Bruchhaus
- Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany.
| | - Michaela Petter
- Department of Medicine, The Peter Doherty Institute, The University of Melbourne, 792n Elizabeth Street, Melbourne, 3000, VIC, Australia.
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20
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Nielsen MA, Salanti A. High-Throughput Testing of Antibody-Dependent Binding Inhibition of Placental Malaria Parasites. Methods Mol Biol 2015; 1325:241-53. [PMID: 26450394 DOI: 10.1007/978-1-4939-2815-6_20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The particular virulence of Plasmodium falciparum manifests in diverse severe malaria syndromes as cerebral malaria, severe anemia and placental malaria. The cause of both the severity and the diversity of infection outcome, is the ability of the infected erythrocyte (IE) to bind a range of different human receptors through Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) on the surface of the infected cell. As the var genes encoding the large PfEMP1 antigens are extensively polymorphic, vaccine development strategies are focused on targeting the functional binding epitopes. This involves identification of recombinant fragments of PfEMP1s that induce antibodies, which hinder the adhesion of the IE to a given receptor or tissue. Different assays to measure the blocking of adhesion have been described in the literature, each with different advantages. This chapter describes a high-throughput assay used in the preclinical and clinical development of a VAR2CSA based vaccine against placental malaria.
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Affiliation(s)
- Morten A Nielsen
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, CSS Building 22/23, Øster Farimagsgade 5, 2099, Copenhagen K, 1014, Denmark.
| | - Ali Salanti
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, CSS Building 22/23, Øster Farimagsgade 5, 2099, Copenhagen K, 1014, Denmark.
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21
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Jones MW, Dearnley MK, van Riessen GA, Abbey B, Putkunz CT, Junker MD, Vine DJ, McNulty I, Nugent KA, Peele AG, Tilley L. Rapid, low dose X-ray diffractive imaging of the malaria parasite Plasmodium falciparum. Ultramicroscopy 2014; 143:88-92. [DOI: 10.1016/j.ultramic.2013.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 09/23/2013] [Accepted: 09/23/2013] [Indexed: 11/30/2022]
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22
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Tokumasu F, Crivat G, Ackerman H, Hwang J, Wellems TE. Inward cholesterol gradient of the membrane system in P. falciparum-infected erythrocytes involves a dilution effect from parasite-produced lipids. Biol Open 2014; 3:529-41. [PMID: 24876390 PMCID: PMC4058088 DOI: 10.1242/bio.20147732] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum (Pf) infection remodels the human erythrocyte with new membrane systems, including a modified host erythrocyte membrane (EM), a parasitophorous vacuole membrane (PVM), a tubulovesicular network (TVN), and Maurer's clefts (MC). Here we report on the relative cholesterol contents of these membranes in parasitized normal (HbAA) and hemoglobin S-containing (HbAS, HbAS) erythrocytes. Results from fluorescence lifetime imaging microscopy (FLIM) experiments with a cholesterol-sensitive fluorophore show that membrane cholesterol levels in parasitized erythrocytes (pRBC) decrease inwardly from the EM, to the MC/TVN, to the PVM, and finally to the parasite membrane (PM). Cholesterol depletion of pRBC by methyl-β-cyclodextrin treatment caused a collapse of this gradient. Lipid and cholesterol exchange data suggest that the cholesterol gradient involves a dilution effect from non-sterol lipids produced by the parasite. FLIM signals from the PVM or PM showed little or no difference between parasitized HbAA vs HbS-containing erythrocytes that differed in lipid content, suggesting that malaria parasites may regulate the cholesterol contents of the PVM and PM independently of levels in the host cell membrane. Cholesterol levels may affect raft structures and the membrane trafficking and sorting functions that support Pf survival in HbAA, HbAS and HbSS erythrocytes.
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Affiliation(s)
- Fuyuki Tokumasu
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA Present address: Department of Lipidomics, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Georgeta Crivat
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA Quantum Electronics and Photonics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Hans Ackerman
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
| | - Jeeseong Hwang
- Quantum Electronics and Photonics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Thomas E Wellems
- Malaria Genetics Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
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Rougeron V, Woods CM, Tiedje KE, Bodeau-Livinec F, Migot-Nabias F, Deloron P, Luty AJF, Fowkes FJI, Day KP. Epistatic Interactions between apolipoprotein E and hemoglobin S Genes in regulation of malaria parasitemia. PLoS One 2013; 8:e76924. [PMID: 24116184 PMCID: PMC3792892 DOI: 10.1371/journal.pone.0076924] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 09/04/2013] [Indexed: 11/18/2022] Open
Abstract
Apolipoprotein E is a monomeric protein secreted by the liver and responsible for the transport of plasma cholesterol and triglycerides. The APOE gene encodes 3 isoforms Ɛ4, Ɛ3 and Ɛ2 with APOE Ɛ4 associated with higher plasma cholesterol levels and increased pathogenesis in several infectious diseases (HIV, HSV). Given that cholesterol is an important nutrient for malaria parasites, we examined whether APOE Ɛ4 was a risk factor for Plasmodium infection, in terms of prevalence or parasite density. A cross sectional survey was performed in 508 children aged 1 to 12 years in Gabon during the wet season. Children were screened for Plasmodium spp. infection, APOE and hemoglobin S (HbS) polymorphisms. Median parasite densities were significantly higher in APOE Ɛ4 children for Plasmodium spp. densities compared to non-APOE Ɛ4 children. When stratified for HbS polymorphisms, median Plasmodium spp. densities were significantly higher in HbAA children if they had an APOE Ɛ4 allele compared to those without an APOE Ɛ4 allele. When considering non-APOE Ɛ4 children, there was no quantitative reduction of Plasmodium spp. parasite densities for HbAS compared to HbAA phenotypes. No influence of APOE Ɛ4 on successful Plasmodium liver cell invasion was detected by multiplicity of infection. These results show that the APOE Ɛ4 allele is associated with higher median malaria parasite densities in children likely due to the importance of cholesterol availability to parasite growth and replication. Results suggest an epistatic interaction between APOE and HbS genes such that sickle cell trait only had an effect on parasite density in APOE Ɛ4 children. This suggests a linked pathway of regulation of parasite density involving expression of these genes. These findings have significance for understanding host determinants of regulation of malaria parasite density, the design of clinical trials as well as studies of co-infection with Plasmodium and other pathogens.
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Affiliation(s)
- Virginie Rougeron
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
| | - Caira M. Woods
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
| | - Kathryn E. Tiedje
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
| | - Florence Bodeau-Livinec
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
- UMR216, Institut de Recherche pour le Développement, Paris, France
| | | | - Philippe Deloron
- UMR216, Institut de Recherche pour le Développement, Paris, France
- PRES, Paris Sorbonne Cité, Université Paris Descartes, Paris, France
| | | | - Freya J. I. Fowkes
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
- Centre for Population Health, Macfarlane Burnet Institute of Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Karen P. Day
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, New York, United States of America
- * E-mail:
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Yam XY, Birago C, Fratini F, Di Girolamo F, Raggi C, Sargiacomo M, Bachi A, Berry L, Fall G, Currà C, Pizzi E, Breton CB, Ponzi M. Proteomic analysis of detergent-resistant membrane microdomains in trophozoite blood stage of the human malaria parasite Plasmodium falciparum. Mol Cell Proteomics 2013; 12:3948-61. [PMID: 24045696 DOI: 10.1074/mcp.m113.029272] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular pathogens contribute to a significant proportion of infectious diseases worldwide. The successful strategy of evading the immune system by hiding inside host cells is common to all the microorganism classes, which exploit membrane microdomains, enriched in cholesterol and sphingolipids, to invade and colonize the host cell. These assemblies, with distinct biochemical properties, can be isolated by means of flotation in sucrose density gradient centrifugation because they are insoluble in nonionic detergents at low temperature. We analyzed the protein and lipid contents of detergent-resistant membranes from erythrocytes infected by Plasmodium falciparum, the most deadly human malaria parasite. Proteins associated with membrane microdomains of trophic parasite blood stages (trophozoites) include an abundance of chaperones, molecules involved in vesicular trafficking, and enzymes implicated in host hemoglobin degradation. About 60% of the identified proteins contain a predicted localization signal suggesting a role of membrane microdomains in protein sorting/trafficking. To validate our proteomic data, we raised antibodies against six Plasmodium proteins not characterized previously. All the selected candidates were recovered in floating low-density fractions after density gradient centrifugation. The analyzed proteins localized either to internal organelles, such as the mitochondrion and the endoplasmic reticulum, or to exported membrane structures, the parasitophorous vacuole membrane and Maurer's clefts, implicated in targeting parasite proteins to the host erythrocyte cytosol or surface. The relative abundance of cholesterol and phospholipid species varies in gradient fractions containing detergent-resistant membranes, suggesting heterogeneity in the lipid composition of the isolated microdomain population. This study is the first report showing the presence of cholesterol-rich microdomains with distinct properties and subcellular localization in trophic stages of Plasmodium falciparum.
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Affiliation(s)
- Xue Yan Yam
- University Montpellier II, CNRS UMR 5235, 34095 Montpellier, Cedex 5, France
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25
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Teguh SC, Klonis N, Duffy S, Lucantoni L, Avery VM, Hutton CA, Baell JB, Tilley L. Novel Conjugated Quinoline–Indoles Compromise Plasmodium falciparum Mitochondrial Function and Show Promising Antimalarial Activity. J Med Chem 2013; 56:6200-15. [DOI: 10.1021/jm400656s] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Sandra Duffy
- Eskitis Institute for Drug Discovery, Brisbane Innovation Park, Griffith University,
Nathan QLD 4111, Australia
| | - Leonardo Lucantoni
- Eskitis Institute for Drug Discovery, Brisbane Innovation Park, Griffith University,
Nathan QLD 4111, Australia
| | - Vicky M. Avery
- Eskitis Institute for Drug Discovery, Brisbane Innovation Park, Griffith University,
Nathan QLD 4111, Australia
| | | | - Jonathan B. Baell
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Science, Parkville
VIC 3052, Australia
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26
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Ribacke U, Moll K, Albrecht L, Ahmed Ismail H, Normark J, Flaberg E, Szekely L, Hultenby K, Persson KEM, Egwang TG, Wahlgren M. Improved in vitro culture of Plasmodium falciparum permits establishment of clinical isolates with preserved multiplication, invasion and rosetting phenotypes. PLoS One 2013; 8:e69781. [PMID: 23894537 PMCID: PMC3718792 DOI: 10.1371/journal.pone.0069781] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 06/12/2013] [Indexed: 11/26/2022] Open
Abstract
To be able to robustly propagate P. falciparum at optimal conditions in vitro is of fundamental importance for genotypic and phenotypic studies of both established and fresh clinical isolates. Cryo-preserved P. falciparum isolates from Ugandan children with severe or uncomplicated malaria were investigated for parasite phenotypes under different in vitro growth conditions or studied directly from the peripheral blood. The parasite cultures showed a minimal loss of parasite-mass and preserved percentage of multiple infected pRBCs to that in peripheral blood, maintained adhesive phenotypes and good outgrowth and multiplication rates when grown in suspension and supplemented with gas. In contrast, abnormal and greatly fluctuating levels of multiple infections were observed during static growth conditions and outgrowth and multiplication rates were inferior. Serum, as compared to Albumax, was found necessary for optimal presentation of PfEMP1 at the pRBC surface and/or for binding of serum proteins (immunoglobulins). Optimal in vitro growth conditions of P. falciparum therefore include orbital shaking (50 rev/min), human serum (10%) and a fixed gas composition (5% O2, 5% CO2, 90% N2). We subsequently established 100% of 76 frozen patient isolates and found rosetting with schizont pRBCs in every isolate (>26% schizont rosetting rate). Rosetting during schizogony was often followed by invasion of the bound RBC as seen by regular and time-lapse microscopy as well as transmission electron microscopy. The peripheral parasitemia, the level of rosetting and the rate of multiplication correlated positively to one another for individual isolates. Rosetting was also more frequent with trophozoite and schizont pRBCs of children with severe versus uncomplicated malaria (p<0.002; p<0.004). The associations suggest that rosetting enhances the ability of the parasite to multiply within the human host.
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Affiliation(s)
- Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Letusa Albrecht
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Hodan Ahmed Ismail
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Johan Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Emilie Flaberg
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Laszlo Szekely
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden
| | - Kristina E. M. Persson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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27
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Abstract
The in vitro cultivation of Plasmodium falciparum is absolutely essential for the molecular dissection of parasite biology and still poses several challenges. The dependence on, and interaction with host red blood cells, the tightly regulated stage-specific expression of proteins, and the parasite peculiar demands on nutrients and gaseous environments are only a few aspects that need to be addressed to successfully cultivate P. falciparum in vitro. In this chapter, we present techniques for normal maintenance of the erythrocytic stages of P. falciparum cultures, their synchronization and the generation of clonal cell lines.
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28
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Dixon MWA, Kenny S, McMillan PJ, Hanssen E, Trenholme KR, Gardiner DL, Tilley L. Genetic ablation of a Maurer's cleft protein prevents assembly of the Plasmodium falciparum virulence complex. Mol Microbiol 2011; 81:982-93. [PMID: 21696460 DOI: 10.1111/j.1365-2958.2011.07740.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The malaria parasite Plasmodium falciparum assembles knob structures underneath the erythrocyte membrane that help present the major virulence protein, P. falciparum erythrocyte membrane protein-1 (PfEMP1). Membranous structures called Maurer's clefts are established in the erythrocyte cytoplasm and function as sorting compartments for proteins en route to the RBC membrane, including the knob-associated histidine-rich protein (KAHRP), and PfEMP1. We have generated mutants in which the Maurer's cleft protein, the ring exported protein-1 (REX1) is truncated or deleted. Removal of the C-terminal domain of REX1 compromises Maurer's cleft architecture and PfEMP1-mediated cytoadherance but permits some trafficking of PfEMP1 to the erythrocyte surface. Deletion of the coiled-coil region of REX1 ablates PfEMP1 surface display, trapping PfEMP1 at the Maurer's clefts. Complementation of mutants with REX1 partly restores PfEMP1-mediated binding to the endothelial cell ligand, CD36. Deletion of the coiled-coil region or complete deletion of REX1 is tightly associated with the loss of a subtelomeric region of chromosome 2, encoding KAHRP and other proteins. A KAHRP-green fluorescent protein (GFP) fusion expressed in the REX1-deletion parasites shows defective trafficking. Thus, loss of functional REX1 directly or indirectly ablates the assembly of the P. falciparum virulence complex at the surface of host erythrocytes.
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Affiliation(s)
- Matthew W A Dixon
- La Trobe Institute for Molecular Science, Department of Biochemistry and Centre of Excellence for Coherent X-ray Science, La Trobe University, Vic. 3086, Australia.
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29
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Tracking Glideosome-associated protein 50 reveals the development and organization of the inner membrane complex of Plasmodium falciparum. EUKARYOTIC CELL 2011; 10:556-64. [PMID: 21239623 DOI: 10.1128/ec.00244-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The most deadly of the human malaria parasites, Plasmodium falciparum, has different stages specialized for invasion of hepatocytes, erythrocytes, and the mosquito gut wall. In each case, host cell invasion is powered by an actin-myosin motor complex that is linked to an inner membrane complex (IMC) via a membrane anchor called the glideosome-associated protein 50 (PfGAP50). We generated P. falciparum transfectants expressing green fluorescent protein (GFP) chimeras of PfGAP50 (PfGAP50-GFP). Using immunoprecipitation and fluorescence photobleaching, we show that C-terminally tagged PfGAP50-GFP can form a complex with endogenous copies of the linker protein PfGAP45 and the myosin A tail domain-interacting protein (MTIP). Full-length PfGAP50-GFP is located in the endoplasmic reticulum in early-stage parasites and then redistributes to apical caps during the formation of daughter merozoites. In the final stage of schizogony, the PfGAP50-GFP profile extends further around the merozoite surface. Three-dimensional (3D) structured illumination microscopy reveals the early-stage IMC as a doubly punctured flat ellipsoid that separates to form claw-shaped apposed structures. A GFP fusion of PfGAP50 lacking the C-terminal membrane anchor is misdirected to the parasitophorous vacuole. Replacement of the acid phosphatase homology domain of PfGAP50 with GFP appears to allow correct trafficking of the chimera but confers a growth disadvantage.
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30
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Hanssen E, Knoechel C, Klonis N, Abu-Bakar N, Deed S, LeGros M, Larabell C, Tilley L. Cryo transmission X-ray imaging of the malaria parasite, P. falciparum. J Struct Biol 2010; 173:161-8. [PMID: 20826218 DOI: 10.1016/j.jsb.2010.08.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/13/2010] [Accepted: 08/25/2010] [Indexed: 11/19/2022]
Abstract
Cryo transmission X-ray microscopy in the "water window" of photon energies has recently been introduced as a method that exploits the natural contrast of biological samples. We have used cryo tomographic X-ray imaging of the intra-erythrocytic malaria parasite, Plasmodium falciparum, to undertake a survey of the cellular features of this important human pathogen. We examined whole hydrated cells at different stages of growth and defined some of the structures with different X-ray density, including the parasite nucleus, cytoplasm, digestive vacuole and the hemoglobin degradation product, hemozoin. As the parasite develops from an early cup-shaped morphology to a more rounded shape, puncta of hemozoin are formed; these coalesce in the mature trophozoite into a central compartment. In some trophozoite stage parasites we observed invaginations of the parasite surface and, using a selective permeabilization process, showed that these remain connected to the RBC cytoplasm. Some of these invaginations have large openings consistent with phagocytic structures and we observed independent endocytic vesicles in the parasite cytoplasm which appear to play a role in hemoglobin uptake. In schizont stage parasites staggered mitosis was observed and X-ray-dense lipid-rich structures were evident at their apical ends of the developing daughter cells. Treatment of parasites with the antimalarial drug artemisinin appears to affect parasite development and their ability to produce the hemoglobin breakdown product, hemozoin.
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Affiliation(s)
- Eric Hanssen
- Electron Microscopy Unit Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
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31
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Fu Y, Tilley L, Kenny S, Klonis N. Dual labeling with a far red probe permits analysis of growth and oxidative stress in P. falciparum-infected erythrocytes. Cytometry A 2010; 77:253-63. [PMID: 20091670 DOI: 10.1002/cyto.a.20856] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The malaria parasite, Plasmodium falciparum, develops within human erythrocytes, consuming host hemoglobin to support its own growth. Reactive oxygen species (superoxide and hydrogen peroxide) are by-products of hemoglobin digestion and are believed to exert significant oxidative stress on the parasite. We have characterized a cell permeant, far red fluorescent nucleic acid-binding dye, SYTO 61, that can be used to distinguish between uninfected and infected erythrocytes in a flow cytometric format. The spectral properties of SYTO 61 make it suitable for use in combination with the fluorescent reactive oxygen species reporter 5-(and-6)-chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate acetyl ester. We have used this probe combination to measure oxidative stress in different stages of live P. falciparum. Low levels of the oxidized, fluorescent form of the reporter (2',7'-dichlorofluorescein, DCF) are detected in ring stage parasites; the DCF signal increases as the intraerythrocytic parasite matures into the trophozoite stage where active hemoglobin digestion occurs. Treatment of infected erythrocytes with the cysteine protease inhibitor, E-64, which inhibits hemoglobin digestion, decreases the DCF signal. We show that E-64 prevents schizont rupture but also causes delayed lethal effects when ring stage cultures are exposed to the drug. We also examined cultures of parasites in erythrocytes harboring 98% catalase inactivation and found no effect on growth and only a modest increase in DCF oxidation.
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Affiliation(s)
- Ying Fu
- Department of Biochemistry, La Trobe University, Melbourne, Victoria, Australia
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32
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Külzer S, Rug M, Brinkmann K, Cannon P, Cowman A, Lingelbach K, Blatch GL, Maier AG, Przyborski JM. Parasite-encoded Hsp40 proteins define novel mobile structures in the cytosol of the P. falciparum-infected erythrocyte. Cell Microbiol 2010; 12:1398-420. [DOI: 10.1111/j.1462-5822.2010.01477.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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33
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Abu Bakar N, Klonis N, Hanssen E, Chan C, Tilley L. Digestive-vacuole genesis and endocytic processes in the early intraerythrocytic stages of Plasmodium falciparum. J Cell Sci 2010; 123:441-50. [PMID: 20067995 DOI: 10.1242/jcs.061499] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The digestive vacuole of the malaria parasite Plasmodium falciparum is the site of haemoglobin digestion and haem detoxification, and is the target of chloroquine and other antimalarials. The mechanisms for genesis of the digestive vacuole and transfer of haemoglobin from the host cytoplasm are still debated. Here, we use live-cell imaging and photobleaching to monitor the uptake of the pH-sensitive fluorescent tracer SNARF-1-dextran from the erythrocyte cytoplasm in ring-stage and trophozoite-stage parasites. We compare these results with electron tomography of serial sections of parasites at different stages of growth. We show that uptake of erythrocyte cytoplasm is initiated in mid-ring-stage parasites. The host cytoplasm is internalised via cytostome-derived invaginations and concentrated into several acidified peripheral structures. Haemoglobin digestion and haemozoin formation take place in these vesicles. The ring-stage parasites can adopt a deeply invaginated cup shape but do not take up haemoglobin via macropinocytosis. As the parasite matures, the haemozoin-containing compartments coalesce to form a single acidic digestive vacuole that is fed by haemoglobin-containing vesicles. There is also evidence for haemoglobin degradation in compartments outside the digestive vacuole. The work has implications for the stage specificity of quinoline and endoperoxide antimalarials.
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34
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Hanssen E, Goldie KN, Tilley L. Ultrastructure of the asexual blood stages of Plasmodium falciparum. Methods Cell Biol 2010; 96:93-116. [PMID: 20869520 DOI: 10.1016/s0091-679x(10)96005-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Plasmodium falciparum is the most deadly of the human malaria parasites. The particular virulence of this species derives from its ability to subvert the physiology of its host during the blood stages of its development. The parasite grows and divides within erythrocytes, feeding on the hemoglobin, and remodeling its host cells so they adhere to blood vessel walls. The advent of molecular transfection technology, coupled with optical microscopy of fluorescent protein reporters, has greatly improved our understanding of the ways in which the malaria parasite alters its host cell. However, a full interpretation of the information from these studies requires similar advances in our knowledge of the ultrastructure of the parasite. Here we give an overview of different electron microscopy techniques that have revealed the fine structure of the parasite at different stages of development. We present data on some of the unusual organelles of P. falciparum, in particular, the membrane structures that are elaborated in the erythrocyte cytoplasm and are thought to play an important role in trafficking of virulence proteins. We present and discuss some of the exciting whole cell imaging techniques that represent a new frontier in the studies of parasite ultrastructure.
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Affiliation(s)
- Eric Hanssen
- Electron Microscopy Unit, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
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35
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Plasmodium falciparum biology: analysis of in vitro versus in vivo growth conditions. Trends Parasitol 2009; 25:474-81. [PMID: 19747879 DOI: 10.1016/j.pt.2009.07.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 06/12/2009] [Accepted: 07/09/2009] [Indexed: 11/22/2022]
Abstract
Recent studies of Plasmodium falciparum isolated directly from infected patients indicate that alternative parasite biological states occur in the natural host that are not observed with in vitro cultivated parasites. Variation in host substrates, immune responses and other factors probably induce modifications in parasite biology. These biological states could have important implications for pathogenesis, transmission and therapy. We review the differences between P. falciparum in vitro culture systems and in vivo host environments, as well as evidence that host conditions can alter pathogen biology. For select biological questions, the incorporation of naturally occurring conditions into in vitro experimental manipulation of microbes may provide novel insight into pathogen biology.
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36
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The malarial parasite Plasmodium falciparum imports the human protein peroxiredoxin 2 for peroxide detoxification. Proc Natl Acad Sci U S A 2009; 106:13323-8. [PMID: 19666612 DOI: 10.1073/pnas.0905387106] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coevolution of the malarial parasite and its human host has resulted in a complex network of interactions contributing to the homeodynamics of the host-parasite unit. As a rapidly growing and multiplying organism, Plasmodium falciparum depends on an adequate antioxidant defense system that is efficient despite the absence of genuine catalase and glutathione peroxidase. Using different experimental approaches, we demonstrate that P. falciparum imports the human redox-active protein peroxiredoxin 2 (hPrx-2, hTPx1) into its cytosol. As shown by confocal microscopy and immunogold electron microscopy, hPrx-2 is also present in the Maurer's clefts, organelles that are described as being involved in parasite protein export. Enzyme kinetic analyses prove that hPrx-2 accepts Plasmodium cytosolic thioredoxin 1 as a reducing substrate. hPrx-2 accounts for roughly 50% of thioredoxin peroxidase activity in parasite extracts, thus indicating a functional role of hPrx-2 as an enzymatic scavenger of peroxides in the parasite. Under chloroquine treatment, a drug promoting oxidative stress, the abundance of hPrx-2 in the parasite increases significantly. P. falciparum has adapted to adopt the hPrx-2, thereby using the host protein for its own purposes.
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37
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Fu Y, Klonis N, Suarna C, Maghzal GJ, Stocker R, Tilley L. A phosphatidylcholine-BODIPY 581/591 conjugate allows mapping of oxidative stress in P. falciparum-infected erythrocytes. Cytometry A 2009; 75:390-404. [PMID: 19148920 DOI: 10.1002/cyto.a.20704] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The chromophore, BODIPY 581/591, has an extended conjugated system that reacts with oxygen centered-radicals leading to changes in its spectral characteristics. Fatty acid-conjugated BODIPY 581/591 transfers readily between membrane bilayers and can be used as a sensor of oxidative stress in cell populations. We report here the use of a phosphatidylcholine (PC) derivative of BODIPY 581/591, which transfers much less rapidly between membranes. This allows the analysis of oxidative stress in individual cells and in different compartments within cells. Quantitative imaging and flow cytometry were used to measure the ratio of fully conjugated to oxidized probe in model systems and in Plasmodium falciparum-infected erythrocytes. We observed an increase in the oxidation of the parasite-associated BODIPY 581/591-PC as the intraerythrocytic parasite matures. By contrast, BODIPY 581/591-PC associated with the erythrocyte membrane experiences a low level of oxidation even in the later stages of parasite development. Treatment with a pro-oxidant compound caused increased oxidation of the probe in the parasite compartment, but less so in the host cell membrane. Conversely, treatment with ferricyanide increases oxidation of the probe in the erythrocyte cell membrane but does not inhibit parasite growth. Chromatographic analysis of the lipids in infected erythrocytes shows no evidence for loss of alpha-tocopherol or the accumulation of lipid hydroperoxides indicating that, despite the increased oxidative stress, the parasite membranes remain protected from substantial lipid oxidation. We have established BODIPY 581/591-PC as a useful probe of the spatial distribution of oxidative stress in P. falciparum-infected erythrocytes; however, the probe appears to be more sensitive to oxidative damage than endogenous lipids.
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Affiliation(s)
- Ying Fu
- Department of Biochemistry, La Trobe University, Melbourne, Victoria 3086, Australia
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38
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Maier AG, Cooke BM, Cowman AF, Tilley L. Malaria parasite proteins that remodel the host erythrocyte. Nat Rev Microbiol 2009; 7:341-54. [PMID: 19369950 DOI: 10.1038/nrmicro2110] [Citation(s) in RCA: 289] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exported proteins of the malaria parasite Plasmodium falciparum interact with proteins of the erythrocyte membrane and induce substantial changes in the morphology, physiology and function of the host cell. These changes underlie the pathology that is responsible for the deaths of 1-2 million children every year due to malaria infections. The advent of molecular transfection technology, including the ability to generate deletion mutants and to introduce fluorescent reporter proteins that track the locations and dynamics of parasite proteins, has increased our understanding of the processes and machinery for export of proteins in P. falciparum-infected erythrocytes and has provided us with insights into the functions of the parasite protein exportome. We review these developments, focusing on parasite proteins that interact with the erythrocyte membrane skeleton or that promote delivery of the major virulence protein, PfEMP1, to the erythrocyte membrane.
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Affiliation(s)
- Alexander G Maier
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria, Australia
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39
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Di Girolamo F, Raggi C, Birago C, Pizzi E, Lalle M, Picci L, Pace T, Bachi A, de Jong J, Janse CJ, Waters AP, Sargiacomo M, Ponzi M. Plasmodium lipid rafts contain proteins implicated in vesicular trafficking and signalling as well as members of the PIR superfamily, potentially implicated in host immune system interactions. Proteomics 2008; 8:2500-13. [PMID: 18563749 DOI: 10.1002/pmic.200700763] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Plasmodium parasites, the causal agents of malaria, dramatically modify the infected erythrocyte by exporting parasite proteins into one or multiple erythrocyte compartments, the cytoplasm and the plasma membrane or beyond. Despite advances in defining signals and specific cellular compartments implicated in protein trafficking in Plasmodium-infected erythrocytes, the contribution of lipid-mediated sorting to this cellular process has been poorly investigated. In this study, we examined the proteome of cholesterol-rich membrane microdomains or lipid rafts, purified from erythrocytes infected by the rodent parasite Plasmodium berghei. Besides structural proteins associated with invasive forms, we detected chaperones, proteins implicated in vesicular trafficking, membrane fusion events and signalling. Interestingly, the raft proteome of mixed P. berghei blood stages included proteins encoded by members of a large family (bir) of putative variant antigens potentially implicated in host immune system interactions and targeted to the surface of the host erythrocytes. The generation of transgenic parasites expressing BIR/GFP fusions confirmed the dynamic association of members of this protein family with membrane microdomains. Our results indicated that lipid rafts in Plasmodium-infected erythrocytes might constitute a route to sort and fold parasite proteins directed to various host cell compartments including the cell surface.
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Affiliation(s)
- Francesco Di Girolamo
- Dipartimento di Malattie Infettive Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Roma, Italy
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40
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Saridaki T, Sanchez CP, Pfahler J, Lanzer M. A conditional export system provides new insights into protein export in Plasmodium falciparum-infected erythrocytes. Cell Microbiol 2008; 10:2483-95. [PMID: 18691247 DOI: 10.1111/j.1462-5822.2008.01223.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human malarial parasite Plasmodium falciparum exports determinants of virulence and pathology to destinations within its host erythrocyte, including the cytoplasm, the plasma membrane and membrane profiles of parasite origin termed Maurer's clefts. While there is some information regarding the signals that allot proteins for export, the trafficking route itself has remained largely obscure, partly due to technical limitations in following protein trafficking with time. To overcome these shortcomings, we have established a conditional protein export system in P. falciparum, based on the previously described conditional aggregation domain (CAD domain) that self-aggregates in the endoplasmic reticulum in a manner that is reversible by the addition of a small molecule. By fusing the CAD domain to the first 80 amino acids of STEVOR and full-length PfSBP1, we were able to control export of a soluble and a transmembrane protein to the erythrocyte cytosol and the Maurer's clefts respectively. The conditional export system allowed us to study the temporal sequence of events of protein export and identify intermediate steps. We further explored the potential of the conditional export system in identifying factors that interact with exported proteins en route. Our data provide evidence for a physical interaction of exported proteins with the molecular chaperone PfBiP during early export steps.
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Affiliation(s)
- Theodora Saridaki
- Hygiene Institut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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41
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Tilley L, Hanssen E. A 3D view of the host cell compartment in P. falciparum-infected erythrocytes. Transfus Clin Biol 2008; 15:72-81. [PMID: 18501653 DOI: 10.1016/j.tracli.2008.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 03/27/2008] [Indexed: 10/22/2022]
Abstract
The most deadly of the human malaria parasites, Plasmodium falciparum, invades the erythrocytes of its host and initiates a remarkable series of morphological rearrangements within the host cell cytoplasm. The mature erythrocyte is effectively a floating sack of haemoglobin with no endogenous protein synthesis or protein trafficking machinery. In order to colonise and remodel its extracellular space, the parasite generates a series of novel structures that are involved in the export of virulence factors to the surface of the host cell. These include extensions of the parasite's vacuolar membrane, known as the tubulovesicular network, and structures referred to as Maurer's clefts. Maurer's clefts are convoluted collections of distorted discs that are tethered to the red blood cell membrane by structures with stalk-like profiles. Recently electron tomography has enabled visualisation--in three dimensions and at unprecedented resolution--the complexity of the membrane systems within the infected RBC cytoplasm.
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Affiliation(s)
- L Tilley
- Department of Biochemistry and Centre of Excellence for Coherent X-ray Science, La Trobe University, Melbourne, Victoria 3086, Australia.
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42
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Struck NS, Herrmann S, Schmuck-Barkmann I, de Souza Dias S, Haase S, Cabrera AL, Treeck M, Bruns C, Langer C, Cowman AF, Marti M, Spielmann T, Gilberger TW. Spatial dissection of the cis- and trans-Golgi compartments in the malaria parasite Plasmodium falciparum. Mol Microbiol 2008; 67:1320-30. [DOI: 10.1111/j.1365-2958.2008.06125.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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43
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Abstract
The phylum Apicomplexa consists of a diverse group of obligate, intracellular parasites. The distinct evolutionary pressures on these protozoans as they have adapted to their respective niches have resulted in a variety of methods that they use to interact with and modify their hosts. One of these is the secretion and trafficking of parasite proteins into the host cell. We review this process for Theileria, Toxoplasma and Plasmodium. We also present what is known about the mechanisms by which parasite proteins are exported into the host cell, as well as information on their known and putative functions once they have reached their final destination.
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Affiliation(s)
- Sandeep Ravindran
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
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44
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Sherman IW. References. ADVANCES IN PARASITOLOGY 2008. [DOI: 10.1016/s0065-308x(08)00430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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45
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Tilley L, Sougrat R, Lithgow T, Hanssen E. The twists and turns of Maurer's cleft trafficking in P. falciparum-infected erythrocytes. Traffic 2007; 9:187-97. [PMID: 18088325 DOI: 10.1111/j.1600-0854.2007.00684.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The malaria parasite, Plasmodium falciparum, invades the red blood cells (RBCs) of its human host and initiates a series of morphological rearrangements within the host cell cytoplasm. The mature RBC has no endogenous trafficking machinery; therefore, the parasite generates novel structures to mediate protein transport. These include compartments called the Maurer's clefts (MC), which play an important role in the trafficking of parasite proteins to the surface of the host cell. Recent electron tomography studies have revealed MC as convoluted flotillas of flattened discs that are tethered to the RBC membrane, prompting speculation that the MC could, in one respect, represent an extracellular equivalent of the Golgi apparatus. Visualization of both resident and cargo proteins has helped decipher the signals and routes for trafficking of parasite proteins to the MC and beyond.
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Affiliation(s)
- Leann Tilley
- Department of Biochemistry, La Trobe University, Melbourne, Victoria 3086, Australia
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46
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Klonis N, Tan O, Jackson K, Goldberg D, Klemba M, Tilley L. Evaluation of pH during cytostomal endocytosis and vacuolar catabolism of haemoglobin in Plasmodium falciparum. Biochem J 2007; 407:343-54. [PMID: 17696875 PMCID: PMC2275073 DOI: 10.1042/bj20070934] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The DV (digestive vacuole) of the malaria parasite, Plasmodium falciparum, is the site of Hb (haemoglobin) digestion and haem detoxification and, as a consequence, the site of action of CQ (chloroquine) and related antimalarials. However, the precise pH of the DV and the endocytic vesicles that feed it has proved difficult to ascertain. We have developed new methods using EGFP [enhanced GFP (green fluorescent protein)] to measure the pH of intracellular compartments. We have generated a series of transfectants in CQ-sensitive and -resistant parasite strains expressing GFP chimaeras of the DV haemoglobinase, plasmepsin II. Using a quantitative flow cytometric assay, the DV pH was determined to be 5.4-5.5. No differences were detected between CQ-sensitive and -resistant strains. We have also developed a method that relies on the pH dependence of GFP photobleaching kinetics to estimate the pH of the DV compartment. This method gives a pH estimate consistent with the intensity-based measurement. Accumulation of the pH-sensitive probe, LysoSensor Blue, in the DV confirms the acidity of this compartment and shows that the cytostomal vesicles are not measurably acidic, indicating that they are unlikely to be the site of Hb digestion or the site of CQ accumulation. We show that a GFP probe located outside the DV reports a pH value close to neutral. The transfectants and methods that we have developed represent useful tools for investigating the pH of GFP-containing compartments and should be of general use in other systems.
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Affiliation(s)
- Nectarios Klonis
- *Department of Biochemistry, La Trobe University, Melbourne, VIC 3086, Australia
| | - Olivia Tan
- *Department of Biochemistry, La Trobe University, Melbourne, VIC 3086, Australia
| | - Katherine Jackson
- *Department of Biochemistry, La Trobe University, Melbourne, VIC 3086, Australia
| | - Daniel Goldberg
- †Department of Medicine, Howard Hughes Medical Institute, Washington University, St. Louis, MO 63110, U.S.A
- ‡Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University, St. Louis, MO 63110, U.S.A
| | - Michael Klemba
- §Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, U.S.A
| | - Leann Tilley
- *Department of Biochemistry, La Trobe University, Melbourne, VIC 3086, Australia
- ∥Centre of Excellence for Coherent X-ray Science, La Trobe University, Melbourne, VIC 3086, Australia
- To whom correspondence should be addressed (email )
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Charpian S, Przyborski JM. Protein Transport Across the Parasitophorous Vacuole of Plasmodium falciparum: Into the Great Wide Open. Traffic 2007; 9:157-65. [DOI: 10.1111/j.1600-0854.2007.00648.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Artemisinin and a series of novel endoperoxide antimalarials exert early effects on digestive vacuole morphology. Antimicrob Agents Chemother 2007; 52:98-109. [PMID: 17938190 DOI: 10.1128/aac.00609-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Artermisinin and its derivatives are now the mainstays of antimalarial treatment; however, their mechanism of action is only poorly understood. We report on the synthesis of a novel series of epoxy-endoperoxides that can be prepared in high yields from simple starting materials. Endoperoxides that are disubstituted with alkyl or benzyl side chains show efficient inhibition of the growth of both chloroquine-sensitive and -resistant strains of Plasmodium falciparum. A trans-epoxide with respect to the peroxide linkage increases the activity compared to that of its cis-epoxy counterpart or the parent endoperoxide. The novel endoperoxides do not show a strong interaction with artemisinin. We have compared the mechanism of action of the novel endoperoxides with that of artemisinin. Electron microscopy reveals that the novel endoperoxides cause the early accumulation of endocytic vesicles, while artemisinin causes the disruption of the digestive vacuole membrane. At longer incubation times artemisinin causes extensive loss of organellar structures, while the novel endoperoxides cause myelin body formation as well as the accumulation of endocytic vesicles. An early event following endoperoxide treatment is the redistribution of the pH-sensitive probe LysoSensor Blue from the digestive vacuole to punctate structures. By contrast, neither artemisinin nor the novel endoperoxides caused alterations in the morphology of the endoplasmic reticulum nor showed antagonistic antimalarial activity when they were used with thapsigargin. Analysis of rhodamine 123 uptake by P. falciparum suggests that disruption of the mitochondrial membrane potential occurs as a downstream effect rather than as an initiator of parasite killing. The data suggest that the digestive vacuole is an important initial site of endoperoxide antimalarial activity.
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Characterization of the antibody response against Plasmodium falciparum erythrocyte membrane protein 1 in human volunteers. Infect Immun 2007; 75:5967-73. [PMID: 17923524 DOI: 10.1128/iai.00327-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The immune response against the Plasmodium falciparum variant surface antigen P. falciparum erythrocyte membrane protein 1 (PfEMP1) is a key component of clinical immunity against falciparum malaria. In this study, we used sera from human volunteers who had been infected with the P. falciparum 3D7 strain to investigate the development, specificity, and dynamics of anti-PfEMP1 antibodies measured against six different strain 3D7 Duffy binding-like domain 1alpha (DBL1alpha) fusion proteins. We observed that a parasitemia of 20 to 200 infected erythrocytes per mul was required to trigger an antibody response to DBL1alpha and that antibodies against one DBL1alpha variant cross-react with other DBL1alpha variants. Both serum and purified immunoglobulin Gs (IgGs) were able to agglutinate infected erythrocytes, and purified anti-DBL1alpha IgGs bound to the live infected red blood cell surface in a punctate surface pattern, confirming that the IgGs recognize native PfEMP1. Analysis of sera from tourists naturally infected with P. falciparum suggests that the anti-PfEMP1 antibodies often persisted for more than 100 days after a single infection. These results help to further our understanding of the development of acquired immunity to P. falciparum infections.
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50
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Wickert H, Krohne G. The complex morphology of Maurer's clefts: from discovery to three-dimensional reconstructions. Trends Parasitol 2007; 23:502-9. [PMID: 17888738 DOI: 10.1016/j.pt.2007.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 06/29/2007] [Accepted: 08/29/2007] [Indexed: 11/21/2022]
Abstract
Over 100 years ago, Georg Maurer wrote one of the finest scientific accounts of what is now known as Maurer's dots, or clefts, describing the intracellular changes in red blood cells infected with Plasmodium falciparum. Maurer's clefts have since attracted much attention, and they form an intriguing aspect of parasite biology that may hold the key to the mechanisms by which the intracellular parasite alters red blood cell properties, leading to host pathogenesis and death. This review will focus on the description of the morphology of these clefts, from the first light-microscopic report up to recent three-dimensional reconstructions. Detailed knowledge of these structures should further our understanding of their functions.
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Affiliation(s)
- Hannes Wickert
- Division of Infectious Diseases, University Hospitals Case Medical Center, 2061 Cornell Road, 4th Floor, Cleveland, OH 44106, USA.
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