151
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Peng M, Cascio D, Egea PF. Crystal structure and solution characterization of the thioredoxin-2 from Plasmodium falciparum, a constituent of an essential parasitic protein export complex. Biochem Biophys Res Commun 2014; 456:403-9. [PMID: 25475729 DOI: 10.1016/j.bbrc.2014.11.096] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
Survival of the malaria parasite Plasmodium falciparum when it infects red blood cells depends upon its ability to export hundreds of its proteins beyond an encasing vacuole. Protein export is mediated by a parasite-derived protein complex, the Plasmodium translocon of exported proteins (PTEX), and requires unfolding of the different cargos prior to their translocation across the vacuolar membrane. Unfolding is performed by the AAA+protein unfoldase HSP101/ClpB2 and the thioredoxin-2 enzyme (TRX2). Protein trafficking is dramatically impaired in parasites with defective HSP101 or lacking TRX2. These two PTEX subunits drive export and are targets for the design of a novel class of antimalarials: protein export inhibitors. To rationalize inhibitor design, we solved the crystal structure of Pfal-TRX2 at 2.2-Å resolution. Within the asymmetric unit, the three different copies of this protein disulfide reductase sample its two redox catalytic states. Size exclusion chromatography and small-angle X-ray scattering (SAXS) analyses demonstrate that Pfal-TRX2 is monomeric in solution. A non-conserved N-terminal extension precedes the canonical thioredoxin-fold; although it is not observed in our structure, our solution analysis suggests it is flexible in contrast to Plasmodium thioredoxin-1. This represents a first step towards the reconstitution of the entire PTEX for mechanistic and structural studies.
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Affiliation(s)
- Mindy Peng
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, USA
| | - Duilio Cascio
- Department of Energy Institute for Genomics and Proteomics, UCLA, Los Angeles, USA
| | - Pascal F Egea
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, USA; Molecular Biology Institute, UCLA, Los Angeles, CA, USA.
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152
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Plasmodium falciparum transfected with ultra bright NanoLuc luciferase offers high sensitivity detection for the screening of growth and cellular trafficking inhibitors. PLoS One 2014; 9:e112571. [PMID: 25392998 PMCID: PMC4231029 DOI: 10.1371/journal.pone.0112571] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 10/08/2014] [Indexed: 11/19/2022] Open
Abstract
Drug discovery is a key part of malaria control and eradication strategies, and could benefit from sensitive and affordable assays to quantify parasite growth and to help identify the targets of potential anti-malarial compounds. Bioluminescence, achieved through expression of exogenous luciferases, is a powerful tool that has been applied in studies of several aspects of parasite biology and high throughput growth assays. We have expressed the new reporter NanoLuc (Nluc) luciferase in Plasmodium falciparum and showed it is at least 100 times brighter than the commonly used firefly luciferase. Nluc brightness was explored as a means to achieve a growth assay with higher sensitivity and lower cost. In addition we attempted to develop other screening assays that may help interrogate libraries of inhibitory compounds for their mechanism of action. To this end parasites were engineered to express Nluc in the cytoplasm, the parasitophorous vacuole that surrounds the intraerythrocytic parasite or exported to the red blood cell cytosol. As proof-of-concept, these parasites were used to develop functional screening assays for quantifying the effects of Brefeldin A, an inhibitor of protein secretion, and Furosemide, an inhibitor of new permeation pathways used by parasites to acquire plasma nutrients.
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153
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The conserved clag multigene family of malaria parasites: essential roles in host-pathogen interaction. Drug Resist Updat 2014; 18:47-54. [PMID: 25467627 DOI: 10.1016/j.drup.2014.10.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The clag multigene family is strictly conserved in malaria parasites, but absent from neighboring genera of protozoan parasites. Early research pointed to roles in merozoite invasion and infected cell cytoadherence, but more recent studies have implicated channel-mediated uptake of ions and nutrients from host plasma. Here, we review the current understanding of this gene family, which appears to be central to host-parasite interactions and an important therapeutic target.
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154
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Xiao H, Bryksa BC, Bhaumik P, Gustchina A, Kiso Y, Yao SQ, Wlodawer A, Yada RY. The zymogen of plasmepsin V from Plasmodium falciparum is enzymatically active. Mol Biochem Parasitol 2014; 197:56-63. [PMID: 25447707 PMCID: PMC6310130 DOI: 10.1016/j.molbiopara.2014.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 10/15/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
Abstract
Plasmepsin V, a membrane-bound aspartic protease present in Plasmodium falciparum, is involved in the export of malaria parasite effector proteins into host erythrocytes and therefore is a potential target for antimalarial drug development. The present study reports the bacterial recombinant expression and initial characterization of zymogenic and mature plasmepsin V. A 484-residue truncated form of proplasmepsin (Glu37-Asn521) was fused to a fragment of thioredoxin and expressed as inclusion bodies. Refolding conditions were optimized and zymogen was processed into a mature form via cleavage at the Asn80-Ala81 peptide bond. Mature plasmepsin V exhibited a pH optimum of 5.5-7.0 with Km and kcat of 4.6 μM and 0.24s(-1), respectively, at pH 6.0 using the substrate DABCYL-LNKRLLHETQ-E(EDANS). Furthermore, the prosegment of proplasmepsin V was shown to be nonessential for refolding and inhibition. Unexpectedly, unprocessed proplasmepsin V was enzymatically active with slightly reduced substrate affinity (∼ 2-fold), and similar pH optimum as well as turnover compared to the mature form. Both zymogenic and mature plasmepsin V were partially inhibited by pepstatin A as well as several KNI aspartic protease inhibitors while certain metals strongly inhibited activity. Overall, the present study provides the first report on the nonessentiality of the prosegment for plasmepsin V folding and activity, and therefore, subsequent characterization of its structure-function relationships of both zymogen and mature forms in the development of novel inhibitors with potential antimalarial activities is warranted.
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Affiliation(s)
- Huogen Xiao
- Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G2W1
| | - Brian C Bryksa
- Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G2W1
| | - Prasenjit Bhaumik
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Alla Gustchina
- Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA
| | - Yoshiaki Kiso
- Laboratory of Peptide Science, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan
| | - Shao Q Yao
- Department of Chemistry, National University of Singapore, 3 Science Drive, Singapore 117543, Singapore
| | - Alexander Wlodawer
- Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA
| | - Rickey Y Yada
- Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G2W1; Faculty of Land and Food Systems, University of British Columbia 248-2357 Main Mall Vancouver, BC V6T 1Z4.
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155
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Jensen AN, Chindaudomsate W, Thitiananpakorn K, Mongkolsuk S, Jensen LT. Improper protein trafficking contributes to artemisinin sensitivity in cells lacking the KDAC Rpd3p. FEBS Lett 2014; 588:4018-25. [PMID: 25263705 DOI: 10.1016/j.febslet.2014.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
Abstract
Lysine deacetylases (KDACs) inhibitors may have therapeutic value in anti-malarial combination therapies with artemisinin. To evaluate connections between KDACs and artemisinin, Saccharomyces cerevisiae deletion mutants in KDAC genes were assayed. Deletion of RPD3, but not other KDAC genes, resulted in strong sensitivity to artemisinin, which was also observed in sit4Δ mutants with impaired endoplasmic reticulum (ER) to Golgi protein trafficking. Decreased accumulation of the transporters Pdr5p, Fur4p, and Tat2p was observed in rpd3Δ and sit4Δ cells. The unfolded protein response is induced in rpd3Δ cells consistent with retention of proteins in the ER. Disruption of protein trafficking appears to sensitize cells to artemisinin and targeting these pathways may be useful as part of artemisinin based anti-malarial therapy.
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Affiliation(s)
| | | | | | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Laran T Jensen
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
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156
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Sleebs BE, Gazdik M, O'Neill MT, Rajasekaran P, Lopaticki S, Lackovic K, Lowes K, Smith BJ, Cowman AF, Boddey JA. Transition state mimetics of the Plasmodium export element are potent inhibitors of Plasmepsin V from P. falciparum and P. vivax. J Med Chem 2014; 57:7644-62. [PMID: 25167370 DOI: 10.1021/jm500797g] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Following erythrocyte invasion, malaria parasites export a catalogue of remodeling proteins into the infected cell that enable parasite development in the human host. Export is dependent on the activity of the aspartyl protease, plasmepsin V (PMV), which cleaves proteins within the Plasmodium export element (PEXEL; RxL↓xE/Q/D) in the parasite's endoplasmic reticulum. Here, we generated transition state mimetics of the native PEXEL substrate that potently inhibit PMV isolated from Plasmodium falciparum and Plasmodium vivax. Through optimization, we identified that the activity of the mimetics was completely dependent on the presence of P1 Leu and P3 Arg. Treatment of P. falciparum-infected erythrocytes with a set of optimized mimetics impaired PEXEL processing and killed the parasites. The striking effect of the compounds provides a clearer understanding of the accessibility of the PMV active site and reaffirms the enzyme as an attractive target for the design of future antimalarials.
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Affiliation(s)
- Brad E Sleebs
- The Walter and Eliza Hall Institute of Medical Research , 1G Royal Parade, Parkville 3052, Victoria, Australia
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157
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Export of virulence proteins by malaria-infected erythrocytes involves remodeling of host actin cytoskeleton. Blood 2014; 124:3459-68. [PMID: 25139348 DOI: 10.1182/blood-2014-06-583054] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Following invasion of human red blood cells (RBCs) by the malaria parasite, Plasmodium falciparum, a remarkable process of remodeling occurs in the host cell mediated by trafficking of several hundred effector proteins to the RBC compartment. The exported virulence protein, P falciparum erythrocyte membrane protein 1 (PfEMP1), is responsible for cytoadherence of infected cells to host endothelial receptors. Maurer clefts are organelles essential for protein trafficking, sorting, and assembly of protein complexes. Here we demonstrate that disruption of PfEMP1 trafficking protein 1 (PfPTP1) function leads to severe alterations in the architecture of Maurer's clefts. Furthermore, 2 major surface antigen families, PfEMP1 and STEVOR, are no longer displayed on the host cell surface leading to ablation of cytoadherence to host receptors. PfPTP1 functions in a large complex of proteins and is required for linking of Maurer's clefts to the host actin cytoskeleton.
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158
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Tarr SJ, Moon RW, Hardege I, Osborne AR. A conserved domain targets exported PHISTb family proteins to the periphery of Plasmodium infected erythrocytes. Mol Biochem Parasitol 2014; 196:29-40. [PMID: 25106850 PMCID: PMC4165601 DOI: 10.1016/j.molbiopara.2014.07.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/24/2014] [Accepted: 07/28/2014] [Indexed: 11/19/2022]
Abstract
Multiple P. falciparum PHISTb proteins localise to the erythrocyte periphery. Solubility profiling indicates that these proteins associate with the red cell cytoskeleton. The PRESAN domain and a preceding N-terminal sequence is a novel targeting domain. A protein targeted to the red cell periphery is essential for parasite survival. P. knowlesi and P. vivax homologous domains also confer similar localisation.
During blood-stage infection, malaria parasites export numerous proteins to the host erythrocyte. The Poly-Helical Interspersed Sub-Telomeric (PHIST) proteins are an exported family that share a common ‘PRESAN’ domain, and include numerous members in Plasmodium falciparum, Plasmodium vivax and Plasmodium knowlesi. In P. falciparum, PHIST proteins have been implicated in protein trafficking and intercellular communication. A number of PHIST proteins are essential for parasite survival. Here, we identify nine members of the PHISTb sub-class of PHIST proteins, including one protein known to be essential for parasite survival, that localise to the erythrocyte periphery. These proteins have solubility characteristics consistent with their association with the erythrocyte cytoskeleton. Together, an extended PRESAN domain, comprising the PRESAN domain and preceding sequence, form a novel targeting-domain that is sufficient to localise a protein to the erythrocyte periphery. We validate the role of this domain in RESA, thus identifying a cytoskeleton-binding domain in RESA that functions independently of its known spectrin-binding domain. Our data suggest that some PHISTb proteins may act as cross-linkers of the erythrocyte cytoskeleton. We also show for the first time that peripherally-localised PHISTb proteins are encoded in genomes of P. knowlesi and vivax indicating a conserved role for the extended PRESAN domain of these proteins in targeting to the erythrocyte periphery.
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Affiliation(s)
- Sarah J Tarr
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, UK
| | - Robert W Moon
- Division of Parasitology, MRC National Institute for Medical Research, London, UK
| | - Iris Hardege
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, UK
| | - Andrew R Osborne
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, UK.
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159
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Prajapati SK, Culleton R, Singh OP. Protein trafficking in Plasmodium falciparum-infected red cells and impact of the expansion of exported protein families. Parasitology 2014; 141:1-11. [PMID: 25076418 DOI: 10.1017/s0031182014000948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARY Erythrocytes are extensively remodelled by the malaria parasite following invasion of the cell. Plasmodium falciparum encodes numerous virulence-associated and host-cell remodelling proteins that are trafficked to the cytoplasm, the cell membrane and the surface of the infected erythrocyte. The export of soluble proteins relies on a sequence directing entry into the secretory pathways in addition to an export signal. The export signal consisting of five amino acids is termed the Plasmodium export element (PEXEL) or the vacuole transport signal (VTS). Genome mining studies have revealed that PEXEL/VTS carrying protein families have expanded dramatically in P. falciparum compared with other malaria parasite species, possibly due to lineage-specific expansion linked to the unique requirements of P. falciparum for host-cell remodelling. The functional characterization of such genes and gene families may reveal potential drug targets that could inhibit protein trafficking in infected erythrocytes. This review highlights some of the recent advances and key knowledge gaps in protein trafficking pathways in P. falciparum-infected red cells and speculates on the impact of exported gene families in the trafficking pathway.
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Affiliation(s)
- Surendra K Prajapati
- Molecular Biology Division,National Institute of Malaria Research,New Delhi,India
| | - Richard Culleton
- Malaria Unit,Institute for Tropical Medicine (NEKKEN), Nagasaki University,Nagasaki,Japan
| | - Om P Singh
- Molecular Biology Division,National Institute of Malaria Research,New Delhi,India
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160
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Beck JR, Muralidharan V, Oksman A, Goldberg DE. PTEX component HSP101 mediates export of diverse malaria effectors into host erythrocytes. Nature 2014; 511:592-5. [PMID: 25043010 PMCID: PMC4130291 DOI: 10.1038/nature13574] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 06/11/2014] [Indexed: 12/02/2022]
Affiliation(s)
- Josh R Beck
- 1] Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110, USA [2]
| | - Vasant Muralidharan
- 1] Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA [2] Howard Hughes Medical Institute, Washington University School of Medicine, St Louis, Missouri 63110, USA [3] [4] Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Anna Oksman
- 1] Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110, USA [2] Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA [3] Howard Hughes Medical Institute, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Daniel E Goldberg
- 1] Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110, USA [2] Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA [3] Howard Hughes Medical Institute, Washington University School of Medicine, St Louis, Missouri 63110, USA
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161
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Inhibition of Plasmepsin V activity demonstrates its essential role in protein export, PfEMP1 display, and survival of malaria parasites. PLoS Biol 2014; 12:e1001897. [PMID: 24983235 PMCID: PMC4077696 DOI: 10.1371/journal.pbio.1001897] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 05/22/2014] [Indexed: 11/19/2022] Open
Abstract
The malaria parasite Plasmodium falciparum exports several hundred proteins into the infected erythrocyte that are involved in cellular remodeling and severe virulence. The export mechanism involves the Plasmodium export element (PEXEL), which is a cleavage site for the parasite protease, Plasmepsin V (PMV). The PMV gene is refractory to deletion, suggesting it is essential, but definitive proof is lacking. Here, we generated a PEXEL-mimetic inhibitor that potently blocks the activity of PMV isolated from P. falciparum and Plasmodium vivax. Assessment of PMV activity in P. falciparum revealed PEXEL cleavage occurs cotranslationaly, similar to signal peptidase. Treatment of P. falciparum-infected erythrocytes with the inhibitor caused dose-dependent inhibition of PEXEL processing as well as protein export, including impaired display of the major virulence adhesin, PfEMP1, on the erythrocyte surface, and cytoadherence. The inhibitor killed parasites at the trophozoite stage and knockdown of PMV enhanced sensitivity to the inhibitor, while overexpression of PMV increased resistance. This provides the first direct evidence that PMV activity is essential for protein export in Plasmodium spp. and for parasite survival in human erythrocytes and validates PMV as an antimalarial drug target.
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162
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Mastan BS, Kumari A, Gupta D, Mishra S, Kumar KA. Gene disruption reveals a dispensable role for plasmepsin VII in the Plasmodium berghei life cycle. Mol Biochem Parasitol 2014; 195:10-3. [PMID: 24893340 DOI: 10.1016/j.molbiopara.2014.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/14/2014] [Accepted: 05/22/2014] [Indexed: 12/20/2022]
Abstract
Plasmepsins (PM), aspartic proteases of Plasmodium, comprises a family of ten proteins that perform critical functions in Plasmodium life cycle. Except VII and VIII, functions of the remaining plasmepsin members have been well characterized. Here, we have generated a mutant parasite lacking PM VII in Plasmodium berghei using reverse genetics approach. Systematic comparison of growth kinetics and infection in both mosquito and vertebrate host revealed that PM VII depleted mutants exhibited no defects in development and progressed normally throughout the parasite life cycle. These studies suggest a dispensable role for PM VII in Plasmodium berghei life cycle.
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Affiliation(s)
- Babu S Mastan
- Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Anchala Kumari
- Bioinformatics Laboratory, SCB Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, 110 067 New Delhi, India
| | - Dinesh Gupta
- Bioinformatics Laboratory, SCB Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, 110 067 New Delhi, India
| | - Satish Mishra
- Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Kota Arun Kumar
- Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India.
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163
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Long-range repulsion of colloids driven by ion exchange and diffusiophoresis. Proc Natl Acad Sci U S A 2014; 111:6554-9. [PMID: 24748113 DOI: 10.1073/pnas.1322857111] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interactions between surfaces and particles in aqueous suspension are usually limited to distances smaller than 1 μm. However, in a range of studies from different disciplines, repulsion of particles has been observed over distances of up to hundreds of micrometers, in the absence of any additional external fields. Although a range of hypotheses have been suggested to account for such behavior, the physical mechanisms responsible for the phenomenon still remain unclear. To identify and isolate these mechanisms, we perform detailed experiments on a well-defined experimental system, using a setup that minimizes the effects of gravity and convection. Our experiments clearly indicate that the observed long-range repulsion is driven by a combination of ion exchange, ion diffusion, and diffusiophoresis. We develop a simple model that accounts for our data; this description is expected to be directly applicable to a wide range of systems exhibiting similar long-range forces.
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164
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Elsworth B, Crabb BS, Gilson PR. Protein export in malaria parasites: an update. Cell Microbiol 2014; 16:355-63. [PMID: 24418476 DOI: 10.1111/cmi.12261] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/04/2014] [Accepted: 01/06/2014] [Indexed: 11/30/2022]
Abstract
Symptomatic malaria is caused by the infection of human red blood cells (RBCs) with Plasmodium parasites. The RBC is a peculiar environment for parasites to thrive in as they lack many of the normal cellular processes and resources present in other cells. Because of this, Plasmodium spp. have adapted to extensively remodel the host cell through the export of hundreds of proteins that have a range of functions, the best known of which are virulence-associated. Many exported parasite proteins are themselves involved in generating a novel trafficking system in the RBC that further promotes export. In this review we provide an overview of the parasite synthesized export machinery as well as recent developments in how different classes of exported proteins are recognized by this machinery.
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Affiliation(s)
- Brendan Elsworth
- Burnet Institute, 85 Commercial Road, Melbourne, Vic., 3004, Australia; Monash University, Clayton, Vic., Australia
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165
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Ingmundson A, Alano P, Matuschewski K, Silvestrini F. Feeling at home from arrival to departure: protein export and host cell remodelling during Plasmodium liver stage and gametocyte maturation. Cell Microbiol 2014; 16:324-33. [PMID: 24330249 DOI: 10.1111/cmi.12251] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 12/09/2013] [Accepted: 12/09/2013] [Indexed: 12/19/2022]
Abstract
Obligate intracellular pathogens actively remodel their host cells to boost propagation, survival, and persistence. Plasmodium falciparum, the causative agent of the most severe form of malaria, assembles a complex secretory system in erythrocytes. Export of parasite factors to the erythrocyte membrane is essential for parasite sequestration from the blood circulation and a major factor for clinical complications in falciparum malaria. Historic and recent molecular reports show that host cell remodelling is not exclusive to P. falciparum and that parasite-induced intra-erythrocytic membrane structures and protein export occur in several Plasmodia. Comparative analyses of P. falciparum asexual and sexual blood stages and imaging of liver stages from transgenic murine Plasmodium species show that protein export occurs in all intracellular phases from liver infection to sexual differentiation, indicating that mammalian Plasmodium species evolved efficient strategies to renovate erythrocytes and hepatocytes according to the specific needs of each life cycle phase. While the repertoireof identified exported proteins is remarkably expanded in asexual P. falciparum blood stages, the putative export machinery and known targeting signatures are shared across life cycle stages. A better understanding of the molecular mechanisms underlying Plasmodium protein export could assist in designing novel strategies to interrupt transmission between Anopheles mosquitoes and humans.
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Affiliation(s)
- Alyssa Ingmundson
- Max Planck Institute for Infection Biology, Parasitology Unit, 10117, Berlin, Germany
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166
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Meyers MJ, Tortorella MD, Xu J, Qin L, He Z, Lang X, Zeng W, Xu W, Qin L, Prinsen MJ, Sverdrup FM, Eickhoff CS, Griggs DW, Oliva J, Ruminski PG, Jacobsen EJ, Campbell MA, Wood DC, Goldberg DE, Liu X, Lu Y, Lu X, Tu Z, Lu X, Ding K, Chen X. Evaluation of aminohydantoins as a novel class of antimalarial agents. ACS Med Chem Lett 2014; 5:89-93. [PMID: 24900778 DOI: 10.1021/ml400412x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/06/2013] [Indexed: 11/30/2022] Open
Abstract
Given the threat of drug resistance, there is an acute need for new classes of antimalarial agents that act via a unique mechanism of action relative to currently used drugs. We have identified a set of druglike compounds within the Tres Cantos Anti-Malarial Set (TCAMS) which likely act via inhibition of a Plasmodium aspartic protease. Structure-activity relationship analysis and optimization of these aminohydantoins demonstrate that these compounds are potent nanomolar inhibitors of the Plasmodium aspartic proteases PM-II and PM-IV and likely one or more other Plasmodium aspartic proteases. Incorporation of a bulky group, such as a cyclohexyl group, on the aminohydantion N-3 position gives enhanced antimalarial potency while reducing inhibition of human aspartic proteases such as BACE. We have identified compound 8p (CWHM-117) as a promising lead for optimization as an antimalarial drug with a low molecular weight, modest lipophilicity, oral bioavailability, and in vivo antimalarial activity in mice.
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Affiliation(s)
- Marvin J. Meyers
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Micky D. Tortorella
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Jing Xu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Limei Qin
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Zhengxiang He
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Xingfen Lang
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Wentian Zeng
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Wanwan Xu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Li Qin
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Michael J. Prinsen
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Francis M. Sverdrup
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Christopher S. Eickhoff
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - David W. Griggs
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Jonathan Oliva
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Peter G. Ruminski
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - E. Jon Jacobsen
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Mary A. Campbell
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - David C. Wood
- Center
for World Health and Medicine, Saint Louis University, Saint Louis, Missouri 63104, United States
| | - Daniel E. Goldberg
- Howard Hughes Medical Institute, Washington University School of Medicine, Departments of Molecular Microbiology and Medicine,
Saint Louis, Missouri 63110, United States
| | - Xiaorong Liu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Yongzhi Lu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Xin Lu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Zhengchao Tu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Xiaoyun Lu
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Ke Ding
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
| | - Xiaoping Chen
- Guangzhou Institutes of Biomedicine and Health, Chinese
Academy of Sciences, Guangzhou, China
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167
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Abstract
Plasmodium falciparum, the causative agent of malaria, completely remodels the infected human erythrocyte to acquire nutrients and to evade the immune system. For this process, the parasite exports more than 10% of all its proteins into the host cell cytosol, including the major virulence factor PfEMP1 (P. falciparum erythrocyte surface protein 1). This unusual protein trafficking system involves long-known parasite-derived membranous structures in the host cell cytosol, called Maurer's clefts. However, the genesis, role, and function of Maurer's clefts remain elusive. Similarly unclear is how proteins are sorted and how they are transported to and from these structures. Recent years have seen a large increase of knowledge but, as yet, no functional model has been established. In this perspective we review the most important findings and conclude with potential possibilities to shed light into the enigma of Maurer's clefts. Understanding the mechanism and function of these structures, as well as their involvement in protein export in P. falciparum, might lead to innovative control strategies and might give us a handle with which to help to eliminate this deadly parasite.
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168
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Boddey JA, Cowman AF. PlasmodiumNesting: Remaking the Erythrocyte from the Inside Out. Annu Rev Microbiol 2013; 67:243-69. [DOI: 10.1146/annurev-micro-092412-155730] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Justin A. Boddey
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; ,
| | - Alan F. Cowman
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; ,
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169
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Matz JM, Matuschewski K, Kooij TW. Two putative protein export regulators promote Plasmodium blood stage development in vivo. Mol Biochem Parasitol 2013; 191:44-52. [DOI: 10.1016/j.molbiopara.2013.09.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/13/2013] [Accepted: 09/16/2013] [Indexed: 11/17/2022]
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170
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Bouillon A, Giganti D, Benedet C, Gorgette O, Pêtres S, Crublet E, Girard-Blanc C, Witkowski B, Ménard D, Nilges M, Mercereau-Puijalon O, Stoven V, Barale JC. In Silico screening on the three-dimensional model of the Plasmodium vivax SUB1 protease leads to the validation of a novel anti-parasite compound. J Biol Chem 2013; 288:18561-73. [PMID: 23653352 PMCID: PMC3689996 DOI: 10.1074/jbc.m113.456764] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/03/2013] [Indexed: 12/12/2022] Open
Abstract
Widespread drug resistance calls for the urgent development of new antimalarials that target novel steps in the life cycle of Plasmodium falciparum and Plasmodium vivax. The essential subtilisin-like serine protease SUB1 of Plasmodium merozoites plays a dual role in egress from and invasion into host erythrocytes. It belongs to a new generation of attractive drug targets against which specific potent inhibitors are actively searched. We characterize here the P. vivax SUB1 enzyme and show that it displays a typical auto-processing pattern and apical localization in P. vivax merozoites. To search for small PvSUB1 inhibitors, we took advantage of the similarity of SUB1 with bacterial subtilisins and generated P. vivax SUB1 three-dimensional models. The structure-based virtual screening of a large commercial chemical compounds library identified 306 virtual best hits, of which 37 were experimentally confirmed inhibitors and 5 had Ki values of <50 μM for PvSUB1. Interestingly, they belong to different chemical families. The most promising competitive inhibitor of PvSUB1 (compound 2) was equally active on PfSUB1 and displayed anti-P. falciparum and Plasmodium berghei activity in vitro and in vivo, respectively. Compound 2 inhibited the endogenous PfSUB1 as illustrated by the inhibited maturation of its natural substrate PfSERA5 and inhibited parasite egress and subsequent erythrocyte invasion. These data indicate that the strategy of in silico screening of three-dimensional models to select for virtual inhibitors combined with stringent biological validation successfully identified several inhibitors of the PvSUB1 enzyme. The most promising hit proved to be a potent cross-inhibitor of PlasmodiumSUB1, laying the groundwork for the development of a globally active small compound antimalarial.
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Affiliation(s)
- Anthony Bouillon
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - David Giganti
- the Institut Pasteur, Unité de Bioinformatique Structurale, Département de Biologie Structurale et Chimie, F-75015 Paris, France
- CNRS, UMR3258, F-75015 Paris, France
| | - Christophe Benedet
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Olivier Gorgette
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - Stéphane Pêtres
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Elodie Crublet
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Christine Girard-Blanc
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Benoit Witkowski
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Didier Ménard
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Michael Nilges
- the Institut Pasteur, Unité de Bioinformatique Structurale, Département de Biologie Structurale et Chimie, F-75015 Paris, France
- CNRS, UMR3258, F-75015 Paris, France
| | - Odile Mercereau-Puijalon
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - Véronique Stoven
- the Center for Computational Biology, Mines-ParisTech, Fontainebleau F-77300 France, and
- the Institut Curie, INSERM U900, F-75248 Paris, France
| | - Jean-Christophe Barale
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
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171
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Spatial association with PTEX complexes defines regions for effector export into Plasmodium falciparum-infected erythrocytes. Nat Commun 2013; 4:1415. [PMID: 23361006 PMCID: PMC3562467 DOI: 10.1038/ncomms2449] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 01/04/2013] [Indexed: 11/23/2022] Open
Abstract
Export of proteins into the infected erythrocyte is critical for malaria parasite survival. The majority of effector proteins are thought to export via a proteinaceous translocon, resident in the parasitophorous vacuole membrane surrounding the parasite. Identification of the Plasmodium translocon of exported proteins and its biochemical association with exported proteins suggests it performs this role. Direct evidence for this, however, is lacking. Here using viable purified Plasmodium falciparum merozoites and three-dimensional structured illumination microscopy, we investigate remodelling events immediately following parasite invasion. We show that multiple complexes of the Plasmodium translocon of exported proteins localize together in foci that dynamically change in clustering behaviour. Furthermore, we provide conclusive evidence of spatial association between exported proteins and exported protein 2, a core component of the Plasmodium translocon of exported proteins, during native conditions and upon generation of translocation intermediates. These data provide the most direct cellular evidence to date that protein export occurs at regions of the parasitophorous vacuole membrane housing the Plasmodium translocon of exported proteins complex. During red blood cell infection, malaria parasites export hundreds of proteins that remodel the host cell surface. Cowman and colleagues identify a putative protein translocator complex spatially associated with exported proteins, revealing the cellular domains involved in protein export.
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172
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Insight into structural and biochemical determinants of substrate specificity of PFI1625c: Correlation analysis of protein-peptide molecular models. J Mol Graph Model 2013; 43:21-30. [DOI: 10.1016/j.jmgm.2013.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 03/18/2013] [Accepted: 03/28/2013] [Indexed: 11/21/2022]
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173
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Marti M, Spielmann T. Protein export in malaria parasites: many membranes to cross. Curr Opin Microbiol 2013; 16:445-51. [PMID: 23725671 DOI: 10.1016/j.mib.2013.04.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 04/24/2013] [Accepted: 04/30/2013] [Indexed: 11/19/2022]
Abstract
The continuous multiplication of Plasmodium parasites in red blood cells leads to a rapid increase in parasite numbers and is responsible for the disease symptoms of malaria. Survival and virulence of the parasite are linked to parasite-induced changes of the host red blood cells. These alterations require export of a large number of parasite proteins that are trafficked across multiple membranes to reach the host cell. Two classes of exported proteins are known, those with a conserved Plasmodium export element (PEXEL/HT) or those without this motif (PNEPs). Recent work has revealed new aspects of the determinants required for export of these 2 protein classes, shedding new light on the mode of trafficking during the different transport steps en route to the host cell.
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Affiliation(s)
- Matthias Marti
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
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174
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Abstract
Intraerythrocytic malaria parasites send hundreds of effector proteins into the host cell. Diverse modes of export have been proposed for different proteins. In this issue, Grüring et al. (2012) present findings that bring the models together.
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Affiliation(s)
- Daniel E Goldberg
- Howard Hughes Medical Institute, Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
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175
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Regev-Rudzki N, Wilson DW, Carvalho TG, Sisquella X, Coleman BM, Rug M, Bursac D, Angrisano F, Gee M, Hill AF, Baum J, Cowman AF. Cell-cell communication between malaria-infected red blood cells via exosome-like vesicles. Cell 2013; 153:1120-33. [PMID: 23683579 DOI: 10.1016/j.cell.2013.04.029] [Citation(s) in RCA: 417] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 03/12/2013] [Accepted: 04/16/2013] [Indexed: 12/27/2022]
Abstract
Cell-cell communication is an important mechanism for information exchange promoting cell survival for the control of features such as population density and differentiation. We determined that Plasmodium falciparum-infected red blood cells directly communicate between parasites within a population using exosome-like vesicles that are capable of delivering genes. Importantly, communication via exosome-like vesicles promotes differentiation to sexual forms at a rate that suggests that signaling is involved. Furthermore, we have identified a P. falciparum protein, PfPTP2, that plays a key role in efficient communication. This study reveals a previously unidentified pathway of P. falciparum biology critical for survival in the host and transmission to mosquitoes. This identifies a pathway for the development of agents to block parasite transmission from the human host to the mosquito.
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Affiliation(s)
- Neta Regev-Rudzki
- Division of Infection and Immunity, the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
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176
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Trafficked Proteins-Druggable in Plasmodium falciparum? Int J Cell Biol 2013; 2013:435981. [PMID: 23710183 PMCID: PMC3655585 DOI: 10.1155/2013/435981] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Accepted: 03/12/2013] [Indexed: 01/09/2023] Open
Abstract
Malaria is an infectious disease that results in serious health problems in the countries in which it is endemic. Annually this parasitic disease leads to more than half a million deaths; most of these are children in Africa. An effective vaccine is not available, and the treatment of the disease is solely dependent on chemotherapy. However, drug resistance is spreading, and the identification of new drug targets as well as the development of new antimalarials is urgently required. Attention has been drawn to a variety of essential plasmodial proteins, which are targeted to intra- or extracellular destinations, such as the digestive vacuole, the apicoplast, or into the host cell. Interfering with the action or the transport of these proteins will impede proliferation of the parasite. In this mini review, we will shed light on the present discovery of chemotherapeutics and potential drug targets involved in protein trafficking processes in the malaria parasite.
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177
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The exported protein PbCP1 localises to cleft-like structures in the rodent malaria parasite Plasmodium berghei. PLoS One 2013; 8:e61482. [PMID: 23658610 PMCID: PMC3637216 DOI: 10.1371/journal.pone.0061482] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/11/2013] [Indexed: 02/02/2023] Open
Abstract
Protein export into the host red blood cell is one of the key processes in the pathobiology of the malaria parasite Plasmodiumtrl falciparum, which extensively remodels the red blood cell to ensure its virulence and survival. In this study, we aimed to shed further light on the protein export mechanisms in the rodent malaria parasite P. berghei and provide further proof of the conserved nature of host cell remodeling in Plasmodium spp. Based on the presence of an export motif (R/KxLxE/Q/D) termed PEXEL (Plasmodium export element), we have generated transgenic P. berghei parasite lines expressing GFP chimera of putatively exported proteins and analysed one of the newly identified exported proteins in detail. This essential protein, termed PbCP1 (P. berghei Cleft-like Protein 1), harbours an atypical PEXEL motif (RxLxY) and is further characterised by two predicted transmembrane domains (2TMD) in the C-terminal end of the protein. We have functionally validated the unusual PEXEL motif in PbCP1 and analysed the role of the 2TMD region, which is required to recruit PbCP1 to discrete membranous structures in the red blood cell cytosol that have a convoluted, vesico-tubular morphology by electron microscopy. Importantly, this study reveals that rodent malaria species also induce modifications to their host red blood cell.
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178
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Yaeno T, Shirasu K. The RXLR motif of oomycete effectors is not a sufficient element for binding to phosphatidylinositol monophosphates. PLANT SIGNALING & BEHAVIOR 2013; 8:e23865. [PMID: 23425855 PMCID: PMC7030308 DOI: 10.4161/psb.23865] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The translocation of effector proteins into the host plant cells is essential for pathogens to suppress plant immune responses. The oomycete pathogen Phytophthora infestans secretes AVR3a, a crucial virulence effector protein with an N-terminal RXLR motif that is required for this translocation. It has been reported that the RXLR motif of P. sojae Avr1b, which is a close homolog of AVR3a, is required for binding to phosphatidylinositol monophosphates (PIPs). However, in our previous report, AVR3a as well as Avr1b bind to PIPs not via RXLR but via lysine residues forming a positively-charged area in the effector domain. In this report, we examined whether other RXLR effectors whose structures have been determined bind to PIPs. Both P. capsici AVR3a11 and Hyaloperonospora arabidopsidis ATR1 have an RXLR motif in their N-terminal regions but did not bind to any PIPs. These results suggest that the RXLR motif is not sufficient for PIP binding.
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Affiliation(s)
- Takashi Yaeno
- Plant Science Center; RIKEN; Tsurumi, Yokohama, Kanagawa, Japan
- * Correspondence to: Takashi Yaeno;
| | - Ken Shirasu
- Plant Science Center; RIKEN; Tsurumi, Yokohama, Kanagawa, Japan
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179
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The N-terminal segment of Plasmodium falciparum SURFIN4.1 is required for its trafficking to the red blood cell cytosol through the endoplasmic reticulum. Parasitol Int 2013; 62:215-29. [DOI: 10.1016/j.parint.2012.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 11/24/2022]
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180
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Rawat M, Vijay S, Gupta Y, Tiwari PK, Sharma A. Imperfect duplicate insertions type of mutations in plasmepsin V modulates binding properties of PEXEL motifs of export proteins in Indian Plasmodium vivax. PLoS One 2013; 8:e60077. [PMID: 23555891 PMCID: PMC3612065 DOI: 10.1371/journal.pone.0060077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/21/2013] [Indexed: 01/12/2023] Open
Abstract
Introduction Plasmepsin V (PM-V) have functionally conserved orthologues across the Plasmodium genus who's binding and antigenic processing at the PEXEL motifs for export about 200–300 essential proteins is important for the virulence and viability of the causative Plasmodium species. This study was undertaken to determine P. vivax plasmepsin V Ind (PvPM-V-Ind) PEXEL motif export pathway for pathogenicity-related proteins/antigens export thereby altering plasmodium exportome during erythrocytic stages. Method We identify and characterize Plasmodium vivax plasmepsin-V-Ind (mutant) gene by cloning, sequence analysis, in silico bioinformatic protocols and structural modeling predictions based on docking studies on binding capacity with PEXEL motifs processing in terms of binding and accessibility of export proteins. Results Cloning and sequence analysis for genetic diversity demonstrates PvPM-V-Ind (mutant) gene is highly conserved among all isolates from different geographical regions of India. Imperfect duplicate insertion types of mutations (SVSE from 246–249 AA and SLSE from 266–269 AA) were identified among all Indian isolates in comparison to P.vivax Sal-1 (PvPM-V-Sal 1) isolate. In silico bioinformatics interaction studies of PEXEL peptide and active enzyme reveal that PvPM-V-Ind (mutant) is only active in endoplasmic reticulum lumen and membrane embedding is essential for activation of plasmepsin V. Structural modeling predictions based on docking studies with PEXEL motif show significant variation in substrate protein binding of these imperfect mutations with data mined PEXEL sequences. The predicted variation in the docking score and interacting amino acids of PvPM-V-Ind (mutant) proteins with PEXEL and lopinavir suggests a modulation in the activity of PvPM-V in terms of binding and accessibility at these sites. Conclusion/Significance Our functional modeled validation of PvPM-V-Ind (mutant) imperfect duplicate insertions with data mined PEXEL sequences leading to altered binding and substrate accessibility of the enzyme makes it a plausible target to investigate export mechanisms for in silico virtual screening and novel pharmacophore designing.
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Affiliation(s)
- Manmeet Rawat
- Protein Biochemistry and Structural Biology Division, National Institute of Malaria Research (ICMR), Dwarka, New Delhi, India
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Sonam Vijay
- Protein Biochemistry and Structural Biology Division, National Institute of Malaria Research (ICMR), Dwarka, New Delhi, India
| | - Yash Gupta
- Department of Microbiology and Molecular Biology, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, Uttar Pradesh, India
| | - Pramod Kumar Tiwari
- Centre for Genomics, Molecular and Human Genetics, Jiwaji University, Gwalior, Madhya Pradesh, India
| | - Arun Sharma
- Protein Biochemistry and Structural Biology Division, National Institute of Malaria Research (ICMR), Dwarka, New Delhi, India
- * E-mail:
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181
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Hobbs CV, Tanaka TQ, Muratova O, Van Vliet J, Borkowsky W, Williamson KC, Duffy PE. HIV treatments have malaria gametocyte killing and transmission blocking activity. J Infect Dis 2013; 208:139-48. [PMID: 23539746 DOI: 10.1093/infdis/jit132] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Millions of individuals being treated for human immunodeficiency virus (HIV) live in malaria-endemic areas, but the effects of these treatments on malaria transmission are unknown. While drugs like HIV protease inhibitors (PIs) and trimethoprim-sulfamethoxazole (TMP-SMX) have known activity against parasites during liver or asexual blood stages, their effects on transmission stages require further study. METHODS The HIV PIs lopinavir and saquinavir, the nonnucleoside reverse-transcriptase inhibitor nevirapine, and the antibiotic TMP-SMX were assessed for activity against Plasmodium falciparum transmission stages. The alamarBlue assay was used to determine the effects of drugs on gametocyte viability, and exflagellation was assessed to determine the effects of drugs on gametocyte maturation. The effects of drug on transmission were assessed by calculating the mosquito oocyst count as a marker for infectivity, using standard membrane feeding assays. RESULTS Lopinavir and saquinavir have gametocytocidal and transmission blocking activities at or approaching clinically relevant treatment levels, while nevirapine does not. TMP-SMX is not gametocytocidal, but at prophylactic levels it blocks transmission. CONCLUSIONS Specific HIV treatments have gametocyte killing and transmission-blocking effects. Clinical studies are warranted to evaluate these findings and their potential impact on eradication efforts.
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Affiliation(s)
- Charlotte V Hobbs
- Laboratory of Malaria Vaccinology and Immunology, NIH/NIAID, 12735 Twinbrook Pkwy, Rockville, MD 20852, USA.
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182
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Boddey JA, Carvalho TG, Hodder AN, Sargeant TJ, Sleebs BE, Marapana D, Lopaticki S, Nebl T, Cowman AF. Role of Plasmepsin V in Export of Diverse Protein Families from the
Plasmodium falciparum
Exportome. Traffic 2013; 14:532-50. [DOI: 10.1111/tra.12053] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 01/29/2013] [Accepted: 02/06/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Justin A. Boddey
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
- Department of Medical Biology University of Melbourne Parkville Victoria 3052 Australia
| | - Teresa G. Carvalho
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Anthony N. Hodder
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
- Department of Medical Biology University of Melbourne Parkville Victoria 3052 Australia
| | - Tobias J. Sargeant
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Brad E. Sleebs
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Danushka Marapana
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Sash Lopaticki
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Thomas Nebl
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
| | - Alan F. Cowman
- Division of Infection and Immunity The Walter and Eliza Hall Institute of Medical Research Parkville Victoria 3052 Australia
- Department of Medical Biology University of Melbourne Parkville Victoria 3052 Australia
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183
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Jiang RHY, Stahelin RV, Bhattacharjee S, Haldar K. Eukaryotic virulence determinants utilize phosphoinositides at the ER and host cell surface. Trends Microbiol 2013; 21:145-56. [PMID: 23375057 DOI: 10.1016/j.tim.2012.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 12/12/2012] [Accepted: 12/18/2012] [Indexed: 01/03/2023]
Abstract
Similar to bacteria, eukaryotic pathogens may utilize common strategies of pathogenic secretion, because effector proteins from the oomycete Phytophthora infestans and virulence determinants from the human malaria parasite Plasmodium falciparum share a functionally equivalent host-cell-targeting motif (RxLR-dEER in P. infestans and RxLxE/D/Q in P. falciparum). Here we summarize recent studies that reveal that the malarial motif may function differently than previously envisioned. Binding of the lipid phosphatidylinositol 3-phosphate [PI(3)P] is a critical step in accessing the host for both pathogens, but occurs in different locations. Nanomolar affinity for PI(3)P by these short amino acid motifs suggests that a newly identified mechanism of phosphoinositide binding that unexpectedly occurs in secretory locations has been exploited for virulence by diverse eukaryotic pathogens.
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Affiliation(s)
- Rays H Y Jiang
- Department of Infectious Diseases and Immunology, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
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184
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Tarr SJ, Cryar A, Thalassinos K, Haldar K, Osborne AR. The C-terminal portion of the cleaved HT motif is necessary and sufficient to mediate export of proteins from the malaria parasite into its host cell. Mol Microbiol 2013; 87:835-50. [PMID: 23279267 PMCID: PMC3567231 DOI: 10.1111/mmi.12133] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/17/2012] [Indexed: 12/01/2022]
Abstract
The malaria parasite exports proteins across its plasma membrane and a surrounding parasitophorous vacuole membrane, into its host erythrocyte. Most exported proteins contain a Host Targeting motif (HT motif) that targets them for export. In the parasite secretory pathway, the HT motif is cleaved by the protease plasmepsin V, but the role of the newly generated N-terminal sequence in protein export is unclear. Using a model protein that is cleaved by an exogenous viral protease, we show that the new N-terminal sequence, normally generated by plasmepsin V cleavage, is sufficient to target a protein for export, and that cleavage by plasmepsin V is not coupled directly to the transfer of a protein to the next component in the export pathway. Mutation of the fourth and fifth positions of the HT motif, as well as amino acids further downstream, block or affect the efficiency of protein export indicating that this region is necessary for efficient export. We also show that the fifth position of the HT motif is important for plasmepsin V cleavage. Our results indicate that plasmepsin V cleavage is required to generate a new N-terminal sequence that is necessary and sufficient to mediate protein export by the malaria parasite.
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Affiliation(s)
- Sarah J Tarr
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, UK
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185
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Bullen HE, Crabb BS, Gilson PR. Recent insights into the export of PEXEL/HTS-motif containing proteins in Plasmodium parasites. Curr Opin Microbiol 2012; 15:699-704. [DOI: 10.1016/j.mib.2012.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 09/22/2012] [Accepted: 09/25/2012] [Indexed: 10/27/2022]
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186
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Deponte M, Hoppe HC, Lee MC, Maier AG, Richard D, Rug M, Spielmann T, Przyborski JM. Wherever I may roam: Protein and membrane trafficking in P. falciparum-infected red blood cells. Mol Biochem Parasitol 2012; 186:95-116. [DOI: 10.1016/j.molbiopara.2012.09.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 11/27/2022]
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187
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Aureggi V, Ehmke V, Wieland J, Schweizer WB, Bernet B, Bur D, Meyer S, Rottmann M, Freymond C, Brun R, Breit B, Diederich F. Potent inhibitors of malarial aspartic proteases, the plasmepsins, by hydroformylation of substituted 7-azanorbornenes. Chemistry 2012; 19:155-64. [PMID: 23161835 DOI: 10.1002/chem.201202941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Indexed: 12/23/2022]
Abstract
The increasing prevalence of multidrug-resistant strains of the malarial parasite Plasmodium falciparum requires the urgent development of new therapeutic agents with novel modes of action. The vacuolar malarial aspartic proteases plasmepsin (PM) I, II, and IV are involved in hemoglobin degradation and play a central role in the growth and maturation of the parasite in the human host. We report the structure-based design, synthesis, and in vitro evaluation of a new generation of PM inhibitors featuring a highly decorated 7-azabicyclo[2.2.1]heptane core. While this protonated central core addresses the catalytic Asp dyad, three substituents bind to the flap, the S1/S3, and the S1' pockets of the enzymes. A hydroformylation reaction is the key synthetic step for the introduction of the new vector reaching into the S1' pocket. The configuration of the racemic ligands was confirmed by extensive NMR and X-ray crystallographic analysis. In vitro biological assays revealed high potency of the new inhibitors against the three plasmepsins (IC(50) values down to 6 nM) and good selectivity towards the closely related human cathepsins D and E. The occupancy of the S1' pocket makes an essential contribution to the gain in binding affinity and selectivity, which is particularly large in the case of the PM IV enzyme. Designing non-peptidic ligands for PM II is a valid route to generate compounds that inhibit the entire family of vacuolar plasmepsins.
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Affiliation(s)
- Valentina Aureggi
- Laboratorium für Organische Chemie, ETH Zurich, Hönggerberg HCI, 8093 Zurich, Switzerland
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188
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Uncovering Common Principles in Protein Export of Malaria Parasites. Cell Host Microbe 2012; 12:717-29. [DOI: 10.1016/j.chom.2012.09.010] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/16/2012] [Accepted: 09/04/2012] [Indexed: 11/21/2022]
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189
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Bhattacharjee S, Stahelin RV, Haldar K. Host targeting of virulence determinants and phosphoinositides in blood stage malaria parasites. Trends Parasitol 2012; 28:555-62. [PMID: 23084821 DOI: 10.1016/j.pt.2012.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 09/19/2012] [Accepted: 09/20/2012] [Indexed: 11/25/2022]
Abstract
Blood stage malaria parasites target a 'secretome' of hundreds of proteins including virulence determinants containing a host (cell) targeting (HT) signal, to human erythrocytes. Recent studies reveal that the export mechanism is due to the HT signal binding to the lipid phosphatidylinositol-3-phosphate [PI(3)P] in the parasite endoplasmic reticulum (ER). An aspartic protease plasmepsin V which cleaves a specialized form of the HT signal was previously thought to be the export mechanism, but is now recognized as a dedicated peptidase that cleaves the signal anchor subsequent to PI(3)P binding. We discuss a model of PI(3)P-dependent targeting and PI(3)P biology of a major human pathogen.
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Affiliation(s)
- Souvik Bhattacharjee
- Center for Rare and Neglected Diseases, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA
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190
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Pillai AD, Nguitragool W, Lyko B, Dolinta K, Butler MM, Nguyen ST, Peet NP, Bowlin TL, Desai SA. Solute restriction reveals an essential role for clag3-associated channels in malaria parasite nutrient acquisition. Mol Pharmacol 2012; 82:1104-14. [PMID: 22949525 DOI: 10.1124/mol.112.081224] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The plasmodial surface anion channel (PSAC) increases erythrocyte permeability to many solutes in malaria but has uncertain physiological significance. We used a PSAC inhibitor with different efficacies against channels from two Plasmodium falciparum parasite lines and found concordant effects on transport and in vitro parasite growth when external nutrient concentrations were reduced. Linkage analysis using this growth inhibition phenotype in the Dd2 × HB3 genetic cross mapped the clag3 genomic locus, consistent with a role for two clag3 genes in PSAC-mediated transport. Altered inhibitor efficacy, achieved through allelic exchange or expression switching between the clag3 genes, indicated that the inhibitor kills parasites through direct action on PSAC. In a parasite unable to undergo expression switching, the inhibitor selected for ectopic homologous recombination between the clag3 genes to increase the diversity of available channel isoforms. Broad-spectrum inhibitors, which presumably interact with conserved sites on the channel, also exhibited improved efficacy with nutrient restriction. These findings indicate that PSAC functions in nutrient acquisition for intracellular parasites. Although key questions regarding the channel and its biological role remain, antimalarial drug development targeting PSAC should be pursued.
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Affiliation(s)
- Ajay D Pillai
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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191
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Külzer S, Charnaud S, Dagan T, Riedel J, Mandal P, Pesce ER, Blatch GL, Crabb BS, Gilson PR, Przyborski JM. Plasmodium falciparum-encoded exported hsp70/hsp40 chaperone/co-chaperone complexes within the host erythrocyte. Cell Microbiol 2012; 14:1784-95. [PMID: 22925632 DOI: 10.1111/j.1462-5822.2012.01840.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/17/2012] [Accepted: 07/17/2012] [Indexed: 01/20/2023]
Abstract
Malaria parasites modify their host cell, the mature human erythrocyte. We are interested in the molecules mediating these processes, and have recently described a family of parasite-encoded heat shock proteins (PfHsp40s) that are targeted to the host cell, and implicated in host cell modification. Hsp40s generally function as co-chaperones of members of the Hsp70 family, and until now it was thought that human Hsp70 acts as the PfHsp40 interaction partner within the host cell. Here we revise this hypothesis, and identify and characterize an exported parasite-encoded Hsp70, referred to as PfHsp70-x. PfHsp70-x is exported to the host erythrocyte where it forms a complex with PfHsp40s in structures known as J-dots, and is closely associated with PfEMP1. Interestingly, Hsp70-x is encoded only by parasite species that export the major virulence factor EMP1, implying a possible role for Hsp70-x in EMP1 presentation at the surface of the infected erythrocyte. Our data strongly support the presence of parasite-encoded chaperone/co-chaperone complexes within the host erythrocyte, which are involved in protein traffic through the host cell. The host-pathogen interaction within the infected erythrocyte is more complex than previously thought, and is driven notonly by parasite co-chaperones, but also by the parasite-encoded chaperone Hsp70-x itself.
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Affiliation(s)
- Simone Külzer
- Parasitology, Philipps University Marburg, Marburg, Germany
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192
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Cai H, Kuang R, Gu J, Wang Y. Proteases in malaria parasites - a phylogenomic perspective. Curr Genomics 2012; 12:417-27. [PMID: 22379395 PMCID: PMC3178910 DOI: 10.2174/138920211797248565] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 07/17/2011] [Accepted: 07/20/2011] [Indexed: 12/21/2022] Open
Abstract
Malaria continues to be one of the most devastating global health problems due to the high morbidity and mortality it causes in endemic regions. The search for new antimalarial targets is of high priority because of the increasing prevalence of drug resistance in malaria parasites. Malarial proteases constitute a class of promising therapeutic targets as they play important roles in the parasite life cycle and it is possible to design and screen for specific protease inhibitors. In this mini-review, we provide a phylogenomic overview of malarial proteases. An evolutionary perspective on the origin and divergence of these proteases will provide insights into the adaptive mechanisms of parasite growth, development, infection, and pathogenesis.B
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Affiliation(s)
- Hong Cai
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
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193
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Abstract
Malaria is caused by parasites which live in host erythrocytes and remodel these cells to provide optimally for the parasites’ needs by exporting effector proteins into the host cells. Eight years ago the discovery of a host cell targeting sequence present in both soluble and transmembrane
P. falciparum exported proteins generated a starting point for investigating the mechanism of parasite protein transport into infected erythrocytes. Since then many confusing facts about this targeting signal have emerged. In this paper, I try to make sense of them.
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Affiliation(s)
- Karin Römisch
- Department of Microbiology, Faculty of Biology, Saarland University, Saarbruecken, Germany
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194
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Bozkurt TO, Schornack S, Banfield MJ, Kamoun S. Oomycetes, effectors, and all that jazz. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:483-92. [PMID: 22483402 DOI: 10.1016/j.pbi.2012.03.008] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 03/13/2012] [Accepted: 03/13/2012] [Indexed: 05/20/2023]
Abstract
Plant pathogenic oomycetes secrete a diverse repertoire of effector proteins that modulate host innate immunity and enable parasitic infection. Understanding how effectors evolve, translocate and traffic inside host cells, and perturb host processes are major themes in the study of oomycete-plant interactions. The last year has seen important progress in the study of oomycete effectors with, notably, the elucidation of the 3D structures of five RXLR effectors, and novel insights into how cytoplasmic effectors subvert host cells. In this review, we discuss these and other recent advances and highlight the most important open questions in oomycete effector biology.
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Affiliation(s)
- Tolga O Bozkurt
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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195
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Bhattacharjee S, Speicher KD, Stahelin RV, Speicher DW, Haldar K. PI(3)P-independent and -dependent pathways function together in a vacuolar translocation sequence to target malarial proteins to the host erythrocyte. Mol Biochem Parasitol 2012; 185:106-13. [PMID: 22828070 DOI: 10.1016/j.molbiopara.2012.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/10/2012] [Accepted: 07/15/2012] [Indexed: 11/18/2022]
Abstract
Malaria parasites export 'a secretome' of hundreds of proteins, including major virulence determinants, from their endoplasmic reticulum (ER), past the parasite plasma and vacuolar membranes to the host erythrocyte. The export mechanism is high affinity (nanomolar) binding of a host (cell) targeting (HT) motif RxLxE/D/Q to the lipid phosphatidylinositol 3-phosphate (PI(3)P) in the ER. Cleavage of the HT motif releases the secretory protein from the ER membrane. The HT motif is thought to be the only export signal resident in an N-terminal vacuolar translocation sequence (VTS) that quantitatively targets green fluorescent protein to the erythrocyte. We have previously shown that the R to A mutation in the HT motif, abrogates VTS binding to PI(3)P (K(d)>5 μM). We now show that remarkably, the R to A mutant is exported to the host erythrocyte, for both membrane and soluble reporters, although the efficiency of export is reduced to ~30% of that seen with a complete VTS. Mass spectrometry indicates that the R to A mutant is cleaved at sites upstream of the HT motif. Antibodies to upstream sequences confirm that aberrantly cleaved R to A protein mutant is exported to the erythrocyte. These data suggest that export mechanisms, independent of PI(3)P as well as those dependent on PI(3)P, function together in a VTS to target parasite proteins to the host erythrocyte.
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Affiliation(s)
- Souvik Bhattacharjee
- Center for Rare and Neglected Diseases, University of Notre Dame, 103 Galvin Life Sciences, Notre Dame, IN 46556, USA
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196
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Cruz LN, Wu Y, Craig AG, Garcia CRS. Signal transduction in Plasmodium-Red Blood Cells interactions and in cytoadherence. AN ACAD BRAS CIENC 2012; 84:555-72. [PMID: 22634746 DOI: 10.1590/s0001-37652012005000036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 03/09/2012] [Indexed: 12/19/2022] Open
Abstract
Malaria is responsible for more than 1.5 million deaths each year, especially among children (Snow et al. 2005). Despite of the severity of malaria situation and great effort to the development of new drug targets (Yuan et al. 2011) there is still a relative low investment toward antimalarial drugs. Briefly there are targets classes of antimalarial drugs currently being tested including: kinases, proteases, ion channel of GPCR, nuclear receptor, among others (Gamo et al. 2010). Here we review malaria signal transduction pathways in Red Blood Cells (RBC) as well as infected RBCs and endothelial cells interactions, namely cytoadherence. The last process is thought to play an important role in the pathogenesis of severe malaria. The molecules displayed on the surface of both infected erythrocytes (IE) and vascular endothelial cells (EC) exert themselves as important mediators in cytoadherence, in that they not only induce structural and metabolic changes on both sides, but also trigger multiple signal transduction processes, leading to alteration of gene expression, with the balance between positive and negative regulation determining endothelial pathology during a malaria infection.
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Affiliation(s)
- Laura N Cruz
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Brasil
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197
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LeGrand EK, Alcock J. Turning up the heat: immune brinksmanship in the acute-phase response. QUARTERLY REVIEW OF BIOLOGY 2012; 87:3-18. [PMID: 22518930 DOI: 10.1086/663946] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The acutephase response (APR) is a systemic response to severe trauma, infection, and cancer, although many of the numerous cytokine-mediated components of the APR are incompletely understood. Some of these components, such as fever, reduced availability of iron and zinc, and nutritional restriction due to anorexia, appear to be stressors capable of causing harm to both the pathogen and the host. We review how the host benefits from differences in susceptibility to stress between pathogens and the host. Pathogens, infected host cells, and neoplastic cells are generally more stressed or vulnerable to additional stress than the host because: (a) targeted local inflammation works in synergy with APR stressors; (b) proliferation/growth increases vulnerability to stress; (c) altered pathogen physiology results in pathogen stress or vulnerability; and (d) protective heat shock responses are partially abrogated in pathogens since their responses are utilized by the host to enhance immune responses. Therefore, the host utilizes a coordinated system of endogenous stressors to provide additional levels of defense against pathogens. This model of immune brinksmanship can explain the evolutionary basis for the mutually stressful components of the APR.
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Affiliation(s)
- Edmund Kenwood LeGrand
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee Knoxville, Tennessee 37996, USA.
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198
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Bhattacharjee S, Stahelin RV, Speicher KD, Speicher DW, Haldar K. Endoplasmic reticulum PI(3)P lipid binding targets malaria proteins to the host cell. Cell 2012; 148:201-12. [PMID: 22265412 DOI: 10.1016/j.cell.2011.10.051] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/11/2011] [Accepted: 10/28/2011] [Indexed: 10/14/2022]
Abstract
Hundreds of effector proteins of the human malaria parasite Plasmodium falciparum constitute a "secretome" carrying a host-targeting (HT) signal, which predicts their export from the intracellular pathogen into the surrounding erythrocyte. Cleavage of the HT signal by a parasite endoplasmic reticulum (ER) protease, plasmepsin V, is the proposed export mechanism. Here, we show that the HT signal facilitates export by recognition of the lipid phosphatidylinositol-3-phosphate (PI(3)P) in the ER, prior to and independent of protease action. Secretome HT signals, including those of major virulence determinants, bind PI(3)P with nanomolar affinity and amino acid specificities displayed by HT-mediated export. PI(3)P-enriched regions are detected within the parasite's ER and colocalize with endogenous HT signal on ER precursors, which also display high-affinity binding to PI(3)P. A related pathogenic oomycete's HT signal export is dependent on PI(3)P binding, without cleavage by plasmepsin V. Thus, PI(3)P in the ER functions in mechanisms of secretion and pathogenesis.
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Affiliation(s)
- Souvik Bhattacharjee
- Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, IN 46556, USA
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199
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Jiang RHY, Marti M. A PIP Gets the plasmodium protein export pathway going. Cell Host Microbe 2012; 11:99-100. [PMID: 22341457 DOI: 10.1016/j.chom.2012.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Survival of blood stage malaria parasites requires extensive host cell remodeling, which is facilitated by secretion of parasite proteins via a dedicated protein export pathway. In a recent Cell paper, Bhattacharjee et al., (2012) describe PI(3)P binding as one of the first steps in targeting parasite proteins to the host cell.
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Affiliation(s)
- Rays H Y Jiang
- The Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA
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200
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Mbengue A, Yam XY, Braun-Breton C. Human erythrocyte remodelling during Plasmodium falciparum malaria parasite growth and egress. Br J Haematol 2012; 157:171-9. [PMID: 22313394 DOI: 10.1111/j.1365-2141.2012.09044.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intra-erythrocyte growth and survival of the malarial parasite Plasmodium falciparum is responsible for both uncomplicated and severe malaria cases and depends on the parasite's ability to remodel its host cell. Host cell remodelling has several functions for the parasite, such as acquiring nutrients from the extracellular milieu because of the loss of membrane transporters upon erythrocyte differentiation, avoiding splenic clearance by conferring cytoadhesive properties to the infected erythrocyte, escaping the host immune response by exporting antigenically variant proteins at the red blood cell surface. In addition, parasite-induced changes at the red blood cell membrane and sub-membrane skeleton are also necessary for the efficient release of the parasite progeny from the host cell. Here we review these cellular and molecular changes, which might not only sustain parasite growth but also prepare, at a very early stage, the last step of egress from the host cell.
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Affiliation(s)
- Alassane Mbengue
- CNRS UMR 5235, University Montpellier II, Dynamique des Interactions Membranaires Normales et Pathologiques, Montpellier, France
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