1
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Jain A, Sharma R, Gautam L, Shrivastava P, Singh KK, Vyas SP. Biomolecular interactions between Plasmodium and human host: A basis of targeted antimalarial therapy. ANNALES PHARMACEUTIQUES FRANÇAISES 2024; 82:401-419. [PMID: 38519002 DOI: 10.1016/j.pharma.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 03/12/2024] [Accepted: 03/18/2024] [Indexed: 03/24/2024]
Abstract
Malaria is one of the serious health concerns worldwide as it remains a clinical challenge due to the complex life cycle of the malaria parasite and the morphological changes it undergoes during infection. The malaria parasite multiplies rapidly and spreads in the population by changing its alternative hosts. These various morphological stages of the parasite in the human host cause clinical symptoms (anemia, fever, and coma). These symptoms arise due to the preprogrammed biology of the parasite in response to the human pathophysiological response. Thus, complete elimination becomes one of the major health challenges. Although malaria vaccine(s) are available in the market, they still contain to cause high morbidity and mortality. Therefore, an approach for eradication is needed through the exploration of novel molecular targets by tracking the epidemiological changes the parasite adopts. This review focuses on the various novel molecular targets.
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Affiliation(s)
- Anamika Jain
- Drug Delivery and Research Laboratory, Department of Pharmaceutical Sciences, Dr. Harisingh Gour University, Sagar, M.P., 470003, India
| | - Rajeev Sharma
- Amity Institute of Pharmacy, Amity University Madhya Pradesh, Gwalior, M.P., 474005, India.
| | - Laxmikant Gautam
- Babulal Tarabai Institute of Pharmaceutical Science, Sagar, M.P., 470228, India
| | - Priya Shrivastava
- Drug Delivery and Research Laboratory, Department of Pharmaceutical Sciences, Dr. Harisingh Gour University, Sagar, M.P., 470003, India
| | - Kamalinder K Singh
- School of Pharmacy and Biomedical Sciences, Faculty of Clinical and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, United Kingdom
| | - Suresh P Vyas
- Drug Delivery and Research Laboratory, Department of Pharmaceutical Sciences, Dr. Harisingh Gour University, Sagar, M.P., 470003, India.
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2
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Liu J, Fike KR, Dapper C, Klemba M. Metabolism of host lysophosphatidylcholine in Plasmodium falciparum-infected erythrocytes. Proc Natl Acad Sci U S A 2024; 121:e2320262121. [PMID: 38349879 PMCID: PMC10895272 DOI: 10.1073/pnas.2320262121] [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: 11/28/2023] [Accepted: 01/09/2024] [Indexed: 02/15/2024] Open
Abstract
The human malaria parasite Plasmodium falciparum requires exogenous fatty acids to support its growth during the pathogenic, asexual erythrocytic stage. Host serum lysophosphatidylcholine (LPC) is a significant fatty acid source, yet the metabolic processes responsible for the liberation of free fatty acids from exogenous LPC are unknown. Using an assay for LPC hydrolysis in P. falciparum-infected erythrocytes, we have identified small-molecule inhibitors of key in situ lysophospholipase activities. Competitive activity-based profiling and generation of a panel of single-to-quadruple knockout parasite lines revealed that two enzymes of the serine hydrolase superfamily, termed exported lipase (XL) 2 and exported lipase homolog (XLH) 4, constitute the dominant lysophospholipase activities in parasite-infected erythrocytes. The parasite ensures efficient exogenous LPC hydrolysis by directing these two enzymes to distinct locations: XL2 is exported to the erythrocyte, while XLH4 is retained within the parasite. While XL2 and XLH4 were individually dispensable with little effect on LPC hydrolysis in situ, loss of both enzymes resulted in a strong reduction in fatty acid scavenging from LPC, hyperproduction of phosphatidylcholine, and an enhanced sensitivity to LPC toxicity. Notably, growth of XL/XLH-deficient parasites was severely impaired when cultured in media containing LPC as the sole exogenous fatty acid source. Furthermore, when XL2 and XLH4 activities were ablated by genetic or pharmacologic means, parasites were unable to proliferate in human serum, a physiologically relevant fatty acid source, revealing the essentiality of LPC hydrolysis in the host environment and its potential as a target for anti-malarial therapy.
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Affiliation(s)
- Jiapeng Liu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
| | | | - Christie Dapper
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
| | - Michael Klemba
- Department of Biochemistry, Virginia Tech, Blacksburg, VA24061
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3
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Bhide AR, Surve DH, Jindal AB. Nanocarrier based active targeting strategies against erythrocytic stage of malaria. J Control Release 2023; 362:297-308. [PMID: 37625598 DOI: 10.1016/j.jconrel.2023.08.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/03/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
The Global Technical Strategy for Malaria 2016-2030 aims to achieve a 90% reduction in malaria cases, and strategic planning and execution are crucial for accomplishing this target. This review aims to understand the complex interaction between erythrocytic receptors and parasites and to use this knowledge to actively target the erythrocytic stage of malaria. The review provides insight into the malaria life cycle, which involves various receptors such as glycophorin A, B, C, and D (GPA/B/C/D), complement receptor 1, basigin, semaphorin 7a, Band 3/ GPA, Kx, and heparan sulfate proteoglycan for parasite cellular binding and ingress in the erythrocytic and exo-erythrocytic stages. Synthetic peptides mimicking P. falciparum receptor binding ligands, human serum albumin, chondroitin sulfate, synthetic polymers, and lipids have been utilized as ligands and decorated onto nanocarriers for specific targeting to parasite-infected erythrocytes. The need of the hour for treatment and prophylaxis against malaria is a broadened horizon that includes multiple targeting strategies against the entry, proliferation, and transmission stages of the parasite. Platform technologies with established pre-clinical safety and efficacy should be translated into clinical evaluation and formulation scale-up. Future development should be directed towards nanovaccines as proactive tools against malaria infection.
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Affiliation(s)
- Atharva R Bhide
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India
| | - Dhanashree H Surve
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, United States
| | - Anil B Jindal
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India.
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4
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Bekić V, Kilian N. Novel secretory organelles of parasite origin - at the center of host-parasite interaction. Bioessays 2023; 45:e2200241. [PMID: 37518819 DOI: 10.1002/bies.202200241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 08/01/2023]
Abstract
Reorganization of cell organelle-deprived host red blood cells by the apicomplexan malaria parasite Plasmodium falciparum enables their cytoadherence to endothelial cells that line the microvasculature. This increases the time red blood cells infected with mature developmental stages remain within selected organs such as the brain to avoid the spleen passage, which can lead to severe complications and cumulate in patient death. The Maurer's clefts are a novel secretory organelle of parasite origin established by the parasite in the cytoplasm of the host red blood cell in order to facilitate the establishment of cytoadherence by conducting the trafficking of immunovariant adhesins to the host cell surface. Another important function of the organelle is the sorting of other proteins the parasite traffics into its host cell. Although the organelle is of high importance for the pathology of malaria, additional putative functions, structure, and genesis remain shrouded in mystery more than a century after its discovery. In this review, we highlight our current knowledge about the Maurer's clefts and other novel secretory organelles established within the host cell cytoplasm by human-pathogenic malaria parasites and other parasites that reside within human red blood cells.
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Affiliation(s)
- Viktor Bekić
- School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Nicole Kilian
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
- Department of Medical Biochemistry, Faculty of Basic Medical Sciences, Delta State University, Abraka, Nigeria
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5
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Liu J, Dapper C, Klemba M. Metabolism of host lysophosphatidylcholine in Plasmodium falciparum-infected erythrocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537066. [PMID: 37131712 PMCID: PMC10153170 DOI: 10.1101/2023.04.17.537066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The human malaria parasite Plasmodium falciparum requires exogenous fatty acids to support its growth during the pathogenic, asexual erythrocytic stage. Host serum lysophosphatidylcholine (LPC) is a significant fatty acid source, yet the metabolic processes responsible for the liberation of free fatty acids from exogenous LPC are unknown. Using a novel assay for LPC hydrolysis in P. falciparum-infected erythrocytes, we have identified small-molecule inhibitors of key in situ lysophospholipase activities. Competitive activity-based profiling and generation of a panel of single-to-quadruple knockout parasite lines revealed that two enzymes of the serine hydrolase superfamily, termed exported lipase (XL) 2 and exported lipase homolog (XLH) 4, are the dominant lysophospholipase activities in parasite-infected erythrocytes. The parasite ensures efficient exogenous LPC hydrolysis by directing these two enzymes to distinct locations: XL2 is exported to the erythrocyte, while XLH4 is retained within the parasite. While XL2 and XLH4 were individually dispensable with little effect on LPC hydrolysis in situ, loss of both enzymes resulted in a strong reduction in fatty acid scavenging from LPC, hyperproduction of phosphatidylcholine, and an enhanced sensitivity to LPC toxicity. Notably, growth of XL/XLH-deficient parasites was severely impaired when cultured in media containing LPC as the sole exogenous fatty acid source. Furthermore, when XL2 and XLH4 activities were ablated by genetic or pharmacologic means, parasites were unable to proliferate in human serum, a physiologically-relevant fatty acid source, revealing the essentiality of LPC hydrolysis in the host environment and its potential as a target for anti-malarial therapy.
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Affiliation(s)
- Jiapeng Liu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
| | - Christie Dapper
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
| | - Michael Klemba
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
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6
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Tintó-Font E, Cortés A. Malaria parasites do respond to heat. Trends Parasitol 2022; 38:435-449. [PMID: 35301987 DOI: 10.1016/j.pt.2022.02.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 01/09/2023]
Abstract
The capacity of malaria parasites to respond to changes in their environment at the transcriptional level has been the subject of debate, but recent evidence has unambiguously demonstrated that Plasmodium spp. can produce adaptive transcriptional responses when exposed to some specific types of stress. These include metabolic conditions and febrile temperature. The Plasmodium falciparum protective response to thermal stress is similar to the response in other organisms, but it is regulated by a transcription factor evolutionarily unrelated to the conserved transcription factor that drives the heat shock (HS) response in most eukaryotes. Of the many genes that change expression during HS, only a subset constitutes an authentic response that contributes to parasite survival.
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Affiliation(s)
- Elisabet Tintó-Font
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona 08036, Catalonia, Spain
| | - Alfred Cortés
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona 08036, Catalonia, Spain; ICREA, Barcelona 08010, Catalonia, Spain.
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7
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Kumar T, Maitra S, Rahman A, Bhattacharjee S. A conserved guided entry of tail-anchored pathway is involved in the trafficking of a subset of membrane proteins in Plasmodium falciparum. PLoS Pathog 2021; 17:e1009595. [PMID: 34780541 PMCID: PMC8629386 DOI: 10.1371/journal.ppat.1009595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 11/29/2021] [Accepted: 10/19/2021] [Indexed: 01/22/2023] Open
Abstract
Tail-anchored (TA) proteins are defined by the absence of N-terminus signal sequence and the presence of a single transmembrane domain (TMD) proximal to their C-terminus. They play fundamental roles in cellular processes including vesicular trafficking, protein translocation and quality control. Some of the TA proteins are post-translationally integrated by the Guided Entry of TA (GET) pathway to the cellular membranes; with their N-terminus oriented towards the cytosol and C-terminus facing the organellar lumen. The TA repertoire and the GET machinery have been extensively characterized in the yeast and mammalian systems, however, they remain elusive in the human malaria parasite Plasmodium falciparum. In this study, we bioinformatically predicted a total of 63 TA proteins in the P. falciparum proteome and revealed the association of a subset with the P. falciparum homolog of Get3 (PfGet3). In addition, our proximity labelling studies either definitively identified or shortlisted the other eligible GET constituents, and our in vitro association studies validated associations between PfGet3 and the corresponding homologs of Get4 and Get2 in P. falciparum. Collectively, this study reveals the presence of proteins with hallmark TA signatures and the involvement of evolutionary conserved GET trafficking pathway for their targeted delivery within the parasite. Tail-anchored (TA) membrane proteins are known to play essential cellular functions in the eukaryotes. These proteins are trafficked to their respective destinations by post-translational translocation pathways that are evolutionarily conserved from yeast to human. However, they remain unidentified in the malaria parasite Plasmodium falciparum. We have used bioinformatic prediction algorithms in conjunction with functional validation studies to identify the candidate TA repertoire and some of the homologs of the trafficking machinery in P. falciparum. Initially, we predicted the presence of 63 putative TA proteins localized to distinct compartments within this parasite, including a few confirmed TA homologs in other eukaryotic systems. We then identified and characterized PfGet3 as a central component in the Guided-Entry of TA (GET) translocation machinery, and our bacterial co-expression and pulldown assays with two selected recombinant TA proteins, PfBOS1 and PfUSE1, showed co-association with PfGet3. We also identified PfGet2 and PfGet4 as the other two components of the GET machinery in P. falciparum using proximity biotinylation followed by mass spectrometry. Interestingly, we also found six TA proteins in the parasite enriched in this fraction. We further validated the direct interactions between a few TA candidates, PfGet4 and PfGet2 with PfGet3 using recombinant-based pulldown studies. In conclusion, this study classified a subset of membrane proteins with the TA nomenclature and implicated a previously unidentified GET pathway for their translocation in this apicomplexan parasite.
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Affiliation(s)
- Tarkeshwar Kumar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Satarupa Maitra
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Abdur Rahman
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Souvik Bhattacharjee
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
- * E-mail:
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8
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Das S, Roy B, Chakrabarty S. Non-ribosomal insights into ribosomal P2 protein in Plasmodium falciparum-infected erythrocytes. Microbiologyopen 2021; 10:e1188. [PMID: 34459544 PMCID: PMC8380560 DOI: 10.1002/mbo3.1188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 11/12/2022] Open
Abstract
The enormous complexity of the eukaryotic ribosome has been a real challenge in unlocking the mechanistic aspects of its amazing molecular function during mRNA translation and many non‐canonical activities of ribosomal proteins in eukaryotic cells. While exploring the uncanny nature of ribosomal P proteins in malaria parasites Plasmodium falciparum, the 60S stalk ribosomal P2 protein has been shown to get exported to the infected erythrocyte (IE) surface as an SDS‐resistant oligomer during the early to the mid‐trophozoite stage. Inhibiting IE surface P2 either by monoclonal antibody or through genetic knockdown resulted in nuclear division arrest of the parasite. This strange and serendipitous finding has led us to explore more about un‐canonical cell biology and the structural involvement of P2 protein in Plasmodium in the search for a novel biochemical role during parasite propagation in the human host.
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Affiliation(s)
- Sudipta Das
- Asymmetric Cell Division Laboratory, Division of Infectious Disease and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Bhaskar Roy
- Asymmetric Cell Division Laboratory, Division of Infectious Disease and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Saswata Chakrabarty
- Asymmetric Cell Division Laboratory, Division of Infectious Disease and Immunology, CSIR-Indian Institute of Chemical Biology, Kolkata, India
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9
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Sylvester K, Maher SP, Posfai D, Tran MK, Crawford MC, Vantaux A, Witkowski B, Kyle DE, Derbyshire ER. Characterization of the Tubovesicular Network in Plasmodium vivax Liver Stage Hypnozoites and Schizonts. Front Cell Infect Microbiol 2021; 11:687019. [PMID: 34195101 PMCID: PMC8236947 DOI: 10.3389/fcimb.2021.687019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/24/2021] [Indexed: 12/04/2022] Open
Abstract
Plasmodium is a genus of apicomplexan parasites which replicate in the liver before causing malaria. Plasmodium vivax can also persist in the liver as dormant hypnozoites and cause clinical relapse upon activation, but the molecular mechanisms leading to activation have yet to be discovered. In this study, we use high-resolution microscopy to characterize temporal changes of the P. vivax liver stage tubovesicular network (TVN), a parasitophorous vacuole membrane (PVM)-derived network within the host cytosol. We observe extended membrane clusters, tubules, and TVN-derived vesicles present throughout P. vivax liver stage development. Additionally, we demonstrate an unexpected presence of the TVN in hypnozoites and observe some association of this network to host nuclei. We also reveal that the host water and solute channel aquaporin-3 (AQP3) associates with TVN-derived vesicles and extended membrane clusters. AQP3 has been previously shown to localize to the PVM of P. vivax hypnozoites and liver schizonts but has not yet been shown in association to the TVN. Our results highlight host-parasite interactions occur in both dormant and replicating liver stage P. vivax forms and implicate AQP3 function during this time. Together, these findings enhance our understanding of P. vivax liver stage biology through characterization of the TVN with an emphasis on the presence of this network in dormant hypnozoites.
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Affiliation(s)
- Kayla Sylvester
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Steven P Maher
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Dora Posfai
- Chemistry Department, Duke University, Durham, NC, United States
| | - Michael K Tran
- Chemistry Department, Duke University, Durham, NC, United States
| | | | - Amélie Vantaux
- Malaria Molecular Epidemiology Unit, Pasteur Institute in Cambodia, Phnom Penh, Cambodia
| | - Benoît Witkowski
- Malaria Molecular Epidemiology Unit, Pasteur Institute in Cambodia, Phnom Penh, Cambodia
| | - Dennis E Kyle
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Emily R Derbyshire
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States.,Chemistry Department, Duke University, Durham, NC, United States
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10
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Jonsdottir TK, Gabriela M, Crabb BS, F de Koning-Ward T, Gilson PR. Defining the Essential Exportome of the Malaria Parasite. Trends Parasitol 2021; 37:664-675. [PMID: 33985912 DOI: 10.1016/j.pt.2021.04.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/15/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023]
Abstract
To survive inside red blood cells (RBCs), malaria parasites export many proteins to alter their host cell's physiological properties. Although most proteins of this exportome are involved in immune avoidance or in the trafficking of exported proteins to the host membrane, about 20% are essential for parasite survival in culture but little is known about their biological functions. Here, we have combined information from large-scale genetic screens and targeted gene-disruption studies to tabulate all currently known Plasmodium falciparum exported proteins according to their likelihood of being essential. We also discuss the essential functional pathways that exported proteins might be involved in to help direct research efforts towards a more comprehensive understanding of host-cell remodelling.
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Affiliation(s)
- Thorey K Jonsdottir
- Burnet Institute, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Mikha Gabriela
- Burnet Institute, Melbourne, Victoria 3004, Australia; School of Medicine, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | | | - Paul R Gilson
- Burnet Institute, Melbourne, Victoria 3004, Australia.
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11
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Llorà-Batlle O, Tintó-Font E, Cortés A. Transcriptional variation in malaria parasites: why and how. Brief Funct Genomics 2020; 18:329-341. [PMID: 31114839 DOI: 10.1093/bfgp/elz009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/04/2019] [Accepted: 04/10/2019] [Indexed: 12/24/2022] Open
Abstract
Transcriptional differences enable the generation of alternative phenotypes from the same genome. In malaria parasites, transcriptional plasticity plays a major role in the process of adaptation to fluctuations in the environment. Multiple studies with culture-adapted parasites and field isolates are starting to unravel the different transcriptional alternatives available to Plasmodium falciparum and the underlying molecular mechanisms. Here we discuss how epigenetic variation, directed transcriptional responses and also genetic changes that affect transcript levels can all contribute to transcriptional variation and, ultimately, parasite survival. Some transcriptional changes are driven by stochastic events. These changes can occur spontaneously, resulting in heterogeneity within parasite populations that provides the grounds for adaptation by dynamic natural selection. However, transcriptional changes can also occur in response to external cues. A better understanding of the mechanisms that the parasite has evolved to alter its transcriptome may ultimately contribute to the design of strategies to combat malaria to which the parasite cannot adapt.
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Affiliation(s)
- Oriol Llorà-Batlle
- ISGlobal, Hospital Clínic - Universitat de Barcelona, 08036 Barcelona, Catalonia, Spain
| | - Elisabet Tintó-Font
- ISGlobal, Hospital Clínic - Universitat de Barcelona, 08036 Barcelona, Catalonia, Spain
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12
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Real-time cholesterol sorting in Plasmodium falciparum-erythrocytes as revealed by 3D label-free imaging. Sci Rep 2020; 10:2794. [PMID: 32066816 PMCID: PMC7026401 DOI: 10.1038/s41598-020-59552-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/28/2020] [Indexed: 12/18/2022] Open
Abstract
Cholesterol, a necessary component of animal cell membranes, is also needed by the lethal human malaria parasite Plasmodium falciparum. Because P. falciparum lacks a cholesterol synthesis pathway and malaria patients have low blood cholesterol, we speculated that it scavenges cholesterol from them in some way. We used time-lapse holotomographic microscopy to observe cholesterol transport in live P. falciparum parasites and structurally investigate erythrocyte membranes, both during and after P. falciparum invasion of human erythrocytes. After P. falciparum initially acquired free cholesterol or inner erythrocytic membrane-derived cholesterol, we observed budding lipid membranes elongating into the cytosol and/or membrane segments migrating there and eventually fusing with the parasite membranes, presumably at the parasitophorous vacuole membrane (PVM). Finally, the cholesterol-containing segments were seen to surround the parasite nucleus. Our imaging data suggest that a novel membrane transport system operates in the cytosol of P. falciparum-infected erythrocytes as a cholesterol import system, likely between the PVM and the erythrocyte membrane, and that this transportation process occurs during the live erythrocyte stages of P. falciparum.
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13
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Kume A, Kasai S, Furuya H, Suzuki H. α-Tocopheryl succinate-suppressed development of cerebral malaria in mice. Parasitol Res 2018; 117:3177-3182. [PMID: 30030625 DOI: 10.1007/s00436-018-6016-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 07/12/2018] [Indexed: 12/13/2022]
Abstract
α-Tocopheryl succinate (α-TOS), a derivative of vitamin E, is synthesized by esterification of α-tocopherol. It has been reported that α-TOS inhibits the mitochondrial complex II resulting in generation of reactive oxygen species, which triggers selective apoptosis in a large number of cancer cells, while it appears largely non-toxic towards normal cells. Plasmodium parasites are well known to have high sensitivity to oxidative stress. Thus, α-TOS is suspected to impact Plasmodium parasites by oxidative stress. In this study, to ascertain whether α-TOS is an appropriate candidate for an anti-malarial drug, C57BL/6J mice were infected with P. yoelii 17XL and P. berghei ANKA, a lethal strain of rodent malaria and experimental cerebral malaria (ECM), and treated with several concentrations of α-TOS by intraperitoneal administration on 1, 3, 5, and 7 days post infection (dpi). In addition, the permeability of the blood brain barrier (BBB) was examined by Evans blue staining in ECM on 7 dpi. As a result of α-TOS treatment, parasitemia was decreased and survival rate was significantly increased in mice infected with both parasites. Furthermore, the intensity of Evans blue staining on brains taken from α-TOS-treated mice was weaker than that of untreated mice. This means that α-TOS might inhibit the breakdown of BBB and progress of cerebral malaria. These findings indicate that vitamin E derivatives like α-TOS might be a potential candidate for treatment drugs against malaria.
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Affiliation(s)
- Aiko Kume
- Research Unit for Functional Genomics, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Shunji Kasai
- Eisai Co., Ltd., 13-1 Nishigoken-cho, Shinjuku-ku, Tokyo, 162-0812, Japan
| | - Hana Furuya
- Research Unit for Functional Genomics, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Hiroshi Suzuki
- Research Unit for Functional Genomics, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho, Obihiro, Hokkaido, 080-8555, Japan.
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14
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Kaur J, Hora R. '2TM proteins': an antigenically diverse superfamily with variable functions and export pathways. PeerJ 2018; 6:e4757. [PMID: 29770278 PMCID: PMC5951124 DOI: 10.7717/peerj.4757] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 04/23/2018] [Indexed: 11/20/2022] Open
Abstract
Malaria is a disease that affects millions of people annually. An intracellular habitat and lack of protein synthesizing machinery in erythrocytes pose numerous difficulties for survival of the human pathogen Plasmodium falciparum. The parasite refurbishes the infected red blood cell (iRBC) by synthesis and export of several proteins in an attempt to suffice its metabolic needs and evade the host immune response. Immune evasion is largely mediated by surface display of highly polymorphic protein families known as variable surface antigens. These include the two trans-membrane (2TM) superfamily constituted by multicopy repetitive interspersed family (RIFINs), subtelomeric variable open reading frame (STEVORs) and Plasmodium falciparum Maurer's cleft two trans-membrane proteins present only in P. falciparum and some simian infecting Plasmodium species. Their hypervariable region flanked by 2TM domains exposed on the iRBC surface is believed to generate antigenic diversity. Though historically named "2TM superfamily," several A-type RIFINs and some STEVORs assume one trans-membrane topology. RIFINs and STEVORs share varied functions in different parasite life cycle stages like rosetting, alteration of iRBC rigidity and immune evasion. Additionally, a member of the STEVOR family has been implicated in merozoite invasion. Differential expression of these families in laboratory strains and clinical isolates propose them to be important for host cell survival and defense. The role of RIFINs in modulation of host immune response and presence of protective antibodies against these surface exposed molecules in patient sera highlights them as attractive targets of antimalarial therapies and vaccines. 2TM proteins are Plasmodium export elements positive, and several of these are exported to the infected erythrocyte surface after exiting through the classical secretory pathway within parasites. Cleaved and modified proteins are trafficked after packaging in vesicles to reach Maurer's clefts, while information regarding delivery to the iRBC surface is sparse. Expression and export timing of the RIFIN and Plasmodium falciparum erythrocyte membrane protein1 families correspond to each other. Here, we have compiled and comprehended detailed information regarding orthologues, domain architecture, surface topology, functions and trafficking of members of the "2TM superfamily." Considering the large repertoire of proteins included in the 2TM superfamily and recent advances defining their function in malaria biology, a surge in research carried out on this important protein superfamily is likely.
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Affiliation(s)
- Jasweer Kaur
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Rachna Hora
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
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15
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Sherling ES, van Ooij C. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes. FEMS Microbiol Rev 2017; 40:701-21. [PMID: 27587718 PMCID: PMC5007283 DOI: 10.1093/femsre/fuw016] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2016] [Indexed: 12/22/2022] Open
Abstract
Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. Plasmodium parasites remodel the host erythrocyte in various ways, including the formation of several membranous compartments, together referred to as the exomembrane system, within the erythrocyte cytosol that together are key to the sweeping changes in the host cell.
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Affiliation(s)
- Emma S Sherling
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Christiaan van Ooij
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London NW7 1AA, UK
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16
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Santi-Rocca J, Blanchard N. Membrane trafficking and remodeling at the host-parasite interface. Curr Opin Microbiol 2017; 40:145-151. [PMID: 29175340 DOI: 10.1016/j.mib.2017.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 10/14/2017] [Accepted: 11/13/2017] [Indexed: 11/16/2022]
Abstract
Membrane shape is functionally linked with many cellular processes. The limiting membrane of vacuoles containing Toxoplasma gondii and Plasmodium apicomplexan parasites lies at the host-parasite interface. This membrane comprises intra-vacuolar and extra-vacuolar tubulo-vesicular deformations, which influence host-parasite cross-talk. Here, underscoring specificities and similarities between the T. gondii and Plasmodium contexts, we present recent findings about vacuolar membrane remodeling and its potential roles in parasite fitness and immune recognition. We review in particular the implication of tubulo-vesicular structures in trapping and/or transporting host and parasite components. Understanding how membrane remodeling influences host-pathogen interactions is expected to be critical in the battle against many intracellular pathogens beyond parasites.
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Affiliation(s)
- Julien Santi-Rocca
- Centre de Physiopathologie de Toulouse Purpan (CPTP), INSERM, CNRS, Université de Toulouse, UPS, Toulouse, France
| | - Nicolas Blanchard
- Centre de Physiopathologie de Toulouse Purpan (CPTP), INSERM, CNRS, Université de Toulouse, UPS, Toulouse, France.
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17
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Turnbull LB, Siwo GH, Button-Simons KA, Tan A, Checkley LA, Painter HJ, Llinás M, Ferdig MT. Simultaneous genome-wide gene expression and transcript isoform profiling in the human malaria parasite. PLoS One 2017; 12:e0187595. [PMID: 29112986 PMCID: PMC5675406 DOI: 10.1371/journal.pone.0187595] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 10/23/2017] [Indexed: 12/22/2022] Open
Abstract
Gene expression DNA microarrays have been vital for characterizing whole-genome transcriptional profiles. Nevertheless, their effectiveness relies heavily on the accuracy of genome sequences, the annotation of gene structures, and the sequence-dependent performance of individual probes. Currently available gene expression arrays for the malaria parasite Plasmodium falciparum rely on an average of 2 probes per gene, usually positioned near the 3′ end of genes; consequently, existing designs are prone to measurement bias and cannot capture complexities such as the occurrence of transcript isoforms arising from alternative splicing or alternative start/ stop sites. Here, we describe two novel gene expression arrays with exon-focused probes designed with an average of 12 and 20 probes spanning each gene. This high probe density minimizes signal noise inherent in probe-to-probe sequence-dependent hybridization intensity. We demonstrate that these exon arrays accurately profile genome-wide expression, comparing favorably to currently available arrays and RNA-seq profiling, and can detect alternatively spliced transcript isoforms as well as non-coding RNAs (ncRNAs). Of the 964 candidate alternate splicing events from published RNA-seq studies, 162 are confirmed using the exon array. Furthermore, the exon array predicted 330 previously unidentified alternate splicing events. Gene expression microarrays continue to offer a cost-effective alternative to RNA-seq for the simultaneous monitoring of gene expression and alternative splicing events. Microarrays may even be preferred in some cases due to their affordability and the rapid turn-around of results when hundreds of samples are required for fine-scale systems biology investigations, including the monitoring of the networks of gene co-expression in the emergence of drug resistance.
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Affiliation(s)
- Lindsey B. Turnbull
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University, Indianapolis, Indiana, United States of America
| | - Geoffrey H. Siwo
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- IBM Research Africa, Johannesburg, South Africa
| | - Katrina A. Button-Simons
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Asako Tan
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- Illumina, Madison, Wisconsin, United States of America
| | - Lisa A. Checkley
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Heather J. Painter
- Department of Biochemistry & Molecular Biology and Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Manuel Llinás
- Department of Biochemistry & Molecular Biology and Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Michael T. Ferdig
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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Chalapareddy S, Desai SA. Malaria parasite proteins involved in nutrient channels at the host erythrocyte membrane: advances and questions for future research. INTERNATIONAL JOURNAL OF CURRENT MULTIDISCIPLINARY STUDIES 2017; 3:619-623. [PMID: 28736757 PMCID: PMC5516901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Erythrocytes infected malaria parasites have increased permeability to nutrients and other solutes, as mediated by an unusual ion channel known as the plasmodial surface anion channel (PSAC). Although the increased permeability of infected erythrocytes was identified more than 70 years ago and subsequently characterized with tracer studies, its mechanism and role in parasite biology remained unclear until the introduction of patch-clamp methods and high-throughput screening technologies. These methods discovered and implicated PSAC as the primary mechanism, determined that this channel is essential for parasite development, led to identification of the channel's genes, and stimulated antimalarial drug discovery against this target. Despite these advances, many questions remain about this unusual parasite channel. Our review highlights some recent advances and describes important questions for future research.
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Affiliation(s)
- S Chalapareddy
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Gachibowli, Telangana, India 500046
| | - SA Desai
- Laboratory of Malaria and Vector Research, Division of Intramural Research, NIAID, National Institutes of Health, Rockville, MD, USA 20852
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Edwards RL, Odom John AR. Muddled mechanisms: recent progress towards antimalarial target identification. F1000Res 2016; 5:2514. [PMID: 27803804 PMCID: PMC5070598 DOI: 10.12688/f1000research.9477.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/06/2016] [Indexed: 01/06/2023] Open
Abstract
In the past decade, malaria rates have plummeted as a result of aggressive infection control measures and the adoption of artemisinin-based combination therapies (ACTs). However, a potential crisis looms ahead. Treatment failures to standard antimalarial regimens have been reported in Southeast Asia, and devastating consequences are expected if resistance spreads to the African continent. To prevent a potential public health emergency, the antimalarial arsenal must contain therapeutics with novel mechanisms of action (MOA). An impressive number of high-throughput screening (HTS) campaigns have since been launched, identifying thousands of compounds with activity against one of the causative agents of malaria,
Plasmodium falciparum. Now begins the difficult task of target identification, for which studies are often tedious, labor intensive, and difficult to interpret. In this review, we highlight approaches that have been instrumental in tackling the challenges of target assignment and elucidation of the MOA for hit compounds. Studies that apply these innovative techniques to antimalarial target identification are described, as well as the impact of the data in the field.
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Affiliation(s)
- Rachel L Edwards
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Audrey R Odom John
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA; Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, USA
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20
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Subudhi AK, Boopathi P, Middha S, Acharya J, Rao SN, Mugasimangalam RC, Sirohi P, Kochar SK, Kochar DK, Das A. A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates. GENOMICS DATA 2016; 9:118-25. [PMID: 27489776 PMCID: PMC4961827 DOI: 10.1016/j.gdata.2016.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/10/2016] [Accepted: 07/06/2016] [Indexed: 11/23/2022]
Abstract
Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic's Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.
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Affiliation(s)
- Amit Kumar Subudhi
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India
| | - P.A. Boopathi
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India
| | - Sheetal Middha
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India
| | - Jyoti Acharya
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India
| | | | | | - Paramendra Sirohi
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India
| | - Sanjay K. Kochar
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India
| | | | - Ashis Das
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India
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21
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Ebine K, Hirai M, Sakaguchi M, Yahata K, Kaneko O, Saito-Nakano Y. Plasmodium Rab5b is secreted to the cytoplasmic face of the tubovesicular network in infected red blood cells together with N-acylated adenylate kinase 2. Malar J 2016; 15:323. [PMID: 27316546 PMCID: PMC4912828 DOI: 10.1186/s12936-016-1377-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 06/08/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rab5 GTPase regulates membrane trafficking between the plasma membrane and endosomes and harbours a conserved C-terminal isoprenyl modification that is necessary for membrane recruitment. Plasmodium falciparum encodes three Rab5 isotypes, and one of these, Rab5b (PfRab5b), lacks the C-terminal modification but possesses the N-terminal myristoylation motif. PfRab5b was reported to localize to the parasite periphery. However, the trafficking pathway regulated by PfRab5b is unknown. METHODS A complementation analysis of Rab5 isotypes was performed in Plasmodium berghei. A constitutively active PfRab5b mutant was expressed under the regulation of a ligand-dependent destabilization domain (DD)-tag system in P. falciparum. The localization of PfRab5b was evaluated after removing the ligand followed by selective permeabilization of the membrane with different detergents. Furthermore, P. falciparum N-terminally myristoylated adenylate kinase 2 (PfAK2) was co-expressed with PfRab5b, and trafficking of PfAK2 to the parasitophorous vacuole membrane was examined by confocal microscopy. RESULTS PfRab5b complemented the function of PbRab5b, however, the conventional C-terminally isoprenylated Rab5, PbRab5a or PbRab5c, did not. The constitutively active PfRab5b mutant localized to the cytosol of the parasite and the tubovesicular network (TVN), a region that extends from the parasitophorous vacuole membrane (PVM) in infected red blood cells (iRBCs). By removing the DD-ligand, parasite cytosolic PfRab5b signal disappeared and a punctate structure adjacent to the endoplasmic reticulum (ER) and parasite periphery accumulated. The peripheral PfRab5b was sensitive to extracellular proteolysis after treatment with streptolysin O, which selectively permeabilizes the red blood cell plasma membrane, indicating that PfRab5b localized on the iRBC cytoplasmic face of the TVN. Transport of PfAK2 to the PVM was abrogated by overexpression of PfRab5b, and PfAK2 accumulated in the punctate structure together with PfRab5b. CONCLUSION N-myristoylated Plasmodium Rab5b plays a role that is distinct from that of conventional mammalian Rab5 isotypes. PfRab5b localizes to a compartment close to the ER, translocated to the lumen of the organelle, and co-localizes with PfAK2. PfRab5b and PfAK2 are then transported to the TVN, and PfRab5b localizes on the iRBC cytoplasmic face of TVN. These data demonstrate that PfRab5b is transported from the parasite cytosol to TVN together with N-myristoylated PfAK2 via an uncharacterized membrane-trafficking pathway.
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Affiliation(s)
- Kazuo Ebine
- Department of Parasitology, National Institute of Infectious Diseases, Shinjuku-Ku, Tokyo, Japan. .,Division of Cellular Dynamics, National Institute for Basic Biology, Okazaki, Aichi, Japan.
| | - Makoto Hirai
- Department of Molecular and Cellular Parasitology, Graduate School of Medicine, Juntendo University, Bunkyo-Ku, Tokyo, Japan.,Department of Parasitology, Graduate School of Medicine, Gunma University, Gunma, Japan
| | - Miako Sakaguchi
- Central Laboratory, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Nagasaki, Japan
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Nagasaki, Japan
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Nagasaki, Japan
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, Shinjuku-Ku, Tokyo, Japan.
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Malaria Parasite Proteins and Their Role in Alteration of the Structure and Function of Red Blood Cells. ADVANCES IN PARASITOLOGY 2015; 91:1-86. [PMID: 27015947 DOI: 10.1016/bs.apar.2015.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Malaria, caused by Plasmodium spp., continues to be a major threat to human health and a significant cause of socioeconomic hardship in many countries. Almost half of the world's population live in malaria-endemic regions and many of them suffer one or more, often life-threatening episodes of malaria every year, the symptoms of which are attributable to replication of the parasite within red blood cells (RBCs). In the case of Plasmodium falciparum, the species responsible for most malaria-related deaths, parasite replication within RBCs is accompanied by striking alterations to the morphological, biochemical and biophysical properties of the host cell that are essential for the parasites' survival. To achieve this, the parasite establishes a unique and extensive protein export network in the infected RBC, dedicating at least 6% of its genome to the process. Understanding the full gamut of proteins involved in this process and the mechanisms by which P. falciparum alters the structure and function of RBCs is important both for a more complete understanding of the pathogenesis of malaria and for development of new therapeutic strategies to prevent or treat this devastating disease. This review focuses on what is currently known about exported parasite proteins, their interactions with the RBC and their likely pathophysiological consequences.
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23
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Siwo GH, Smith RS, Tan A, Button-Simons KA, Checkley LA, Ferdig MT. An integrative analysis of small molecule transcriptional responses in the human malaria parasite Plasmodium falciparum. BMC Genomics 2015; 16:1030. [PMID: 26637195 PMCID: PMC4670519 DOI: 10.1186/s12864-015-2165-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 10/29/2015] [Indexed: 12/05/2022] Open
Abstract
Background Transcriptional responses to small molecules can provide insights into drug mode of action (MOA). The capacity of the human malaria parasite, Plasmodium falciparum, to respond specifically to transcriptional perturbations has been unclear based on past approaches. Here, we present the most extensive profiling to date of the parasite’s transcriptional responsiveness to thirty-one chemically and functionally diverse small molecules. Methods We exposed two laboratory strains of the human malaria parasite P. falciparum to brief treatments of thirty-one chemically and functionally diverse small molecules associated with biological effects across multiple pathways based on various levels of evidence. We investigated the impact of chemical composition and MOA on gene expression similarities that arise between perturbations by various compounds. To determine the target biological pathways for each small molecule, we developed a novel framework for encoding small molecule effects on a spectra of biological processes or GO functions that are enriched in the differentially expressed genes of a given small molecule perturbation. Results We find that small molecules associated with similar transcriptional responses contain similar chemical features, and/ or have a shared MOA. The approach also revealed complex relationships between drugs and biological pathways that are missed by most exisiting approaches. For example, the approach was able to partition small molecule responses into drug-specific effects versus non-specific effects. Conclusions Our work provides a new framework for linking transcriptional responses to drug MOA in P. falciparum and can be generalized for the same purpose in other organisms. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2165-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Geoffrey H Siwo
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.,Current Address: IBM TJ Watson Research Center, Yorktown Heights, NY, 10598, USA.,Current Address: IBM Research-Africa, South Africa Lab, Sandton, Johannesburg, 2196, South Africa
| | - Roger S Smith
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.,Current Address: Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Asako Tan
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.,Epicenter, Madison, WI, 53719, USA
| | - Katrina A Button-Simons
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Lisa A Checkley
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Michael T Ferdig
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.
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Probucol-Induced α-Tocopherol Deficiency Protects Mice against Malaria Infection. PLoS One 2015; 10:e0136014. [PMID: 26296197 PMCID: PMC4546625 DOI: 10.1371/journal.pone.0136014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/29/2015] [Indexed: 12/20/2022] Open
Abstract
The emergence of malaria pathogens having resistance against antimalarials implies the necessity for the development of new drugs. Recently, we have demonstrated a resistance against malaria infection of α-tocopherol transfer protein knockout mice showing undetectable plasma levels of α-tocopherol, a lipid-soluble antioxidant. However, dietary restriction induced α-tocopherol deficiency is difficult to be applied as a clinical antimalarial therapy. Here, we report on a new strategy to potentially treat malaria by using probucol, a drug that can reduce the plasma α-tocopherol concentration. Probucol pre-treatment for 2 weeks and treatment throughout the infection rescued from death of mice infected with Plasmodium yoelii XL-17 or P. berghei ANKA. In addition, survival was extended when the treatment started immediately after parasite inoculation. The ratio of lipid peroxidation products to parent lipids increased in plasma after 2 weeks treatment of probucol. This indicates that the protective effect of probucol might be mediated by the oxidative stressful environment induced by α-tocopherol deficiency. Probucol in combination with dihydroartemisin suppressed the proliferation of P. yoelii XL-17. These results indicated that probucol might be a candidate for a drug against malaria infection by inducing α-tocopherol deficiency without dietary α-tocopherol restriction.
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25
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Kaushansky A, Kappe SH. Selection and refinement: the malaria parasite's infection and exploitation of host hepatocytes. Curr Opin Microbiol 2015; 26:71-8. [PMID: 26102161 DOI: 10.1016/j.mib.2015.05.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/16/2015] [Accepted: 05/22/2015] [Indexed: 01/23/2023]
Abstract
Plasmodium parasites belong to the Apicomplexan phylum, which consists mostly of obligate intracellular pathogens that vary dramatically in host cell tropism. Plasmodium sporozoites are highly hepatophilic. The specific molecular mechanisms, which facilitate sporozoite selection and successful infection of hepatocytes, remain poorly defined. Here, we discuss the parasite and host factors which are critical to hepatocyte infection. We derive a model where sporozoites initially select host cells that constitute a permissive environment and then further refine the chosen hepatocyte during liver stage development, ensuring life cycle progression. While many unknowns of pre-erythrocytic infection remain, advancing models and technologies that enable analysis of human malaria parasites and of single infected cells will catalyze a comprehensive understanding of the interaction between the malaria parasite and its hepatocyte host.
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Affiliation(s)
- Alexis Kaushansky
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Ave. N, #500, Seattle, WA 98109, United States.
| | - Stefan Hi Kappe
- Center for Infectious Disease Research, Formerly Seattle Biomedical Research Institute, 307 Westlake Ave. N, #500, Seattle, WA 98109, United States; Department of Global Health, University of Washington, Seattle, WA, United States.
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26
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Caro F, Ahyong V, Betegon M, DeRisi JL. Genome-wide regulatory dynamics of translation in the Plasmodium falciparum asexual blood stages. eLife 2014; 3. [PMID: 25493618 PMCID: PMC4371882 DOI: 10.7554/elife.04106] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Accepted: 11/06/2014] [Indexed: 12/11/2022] Open
Abstract
The characterization of the transcriptome and proteome of Plasmodium
falciparum has been a tremendous resource for the understanding of the
molecular physiology of this parasite. However, the translational dynamics that link
steady-state mRNA with protein levels are not well understood. In this study, we
bridge this disconnect by measuring genome-wide translation using ribosome profiling,
through five stages of the P. falciparum blood phase developmental
cycle. Our findings show that transcription and translation are tightly coupled, with
overt translational control occurring for less than 10% of the transcriptome.
Translationally regulated genes are predominantly associated with merozoite egress
functions. We systematically define mRNA 5′ leader sequences, and 3′
UTRs, as well as antisense transcripts, along with ribosome occupancy for each, and
establish that accumulation of ribosomes on 5′ leaders is a common transcript
feature. This work represents the highest resolution and broadest portrait of gene
expression and translation to date for this medically important parasite. DOI:http://dx.doi.org/10.7554/eLife.04106.001 The genome of an organism includes all of the genes or information necessary to
build, maintain, and replicate that organism. However, cells with the same
genome—such as a skin cell and a liver cell from the same person—can
look and behave very differently depending on which of the genes in their genomes
they express, and to what extent. For a gene to be expressed, its DNA is ‘transcribed’ to make an RNA
molecule, which is then ‘translated’ to make a protein. Efforts to
measure the transcription and translation processes in diseased cells, or in the
microorganisms that cause infections, may lead to new treatments and preventative
medicines. Such work is currently ongoing in the global effort to treat and prevent
malaria. Malaria is both preventable and curable, yet over 600,000 people are estimated to die
from this disease each year. The disease is caused by a single-celled parasite called
Plasmodium. Mosquitoes carry the parasites in their salivary
glands, and when a mosquito bites a human, these parasites are injected into the
bloodstream with the mosquito's saliva. Plasmodium parasites then
travel to and infect the liver, before bursting out of this tissue into the
bloodstream. Here, the parasites infect red blood cells and undergo rounds of
replication during which the symptoms of the disease are manifested. It is also
during this bloodstream phase that parasites can develop into forms capable of
infecting another mosquito and continuing the transmission cycle. The genes, RNA molecules, and proteins of the Plasmodium falciparum
parasite—which causes the most serious cases of malaria in humans—have
been cataloged to better understand the biology of this parasite. However, the
processes that control how, and when, an RNA transcript is translated into a protein
are not well understood. Now Caro et al. have uncovered which RNA molecules are being translated, and by how
much, during Plasmodium development within the blood. The
transcription and translation of genes in this parasite were found to be tightly
linked processes; the expression of only a few genes was controlled more by the
translation process than by transcription. These translationally regulated genes were
found mainly to be those that encode proteins involved in the parasite's exit from
the red blood cells and spread throughout the bloodstream. Caro et al. discovered that genetic regulation of the malaria parasite resembles a
preset genetic program, rather than a system that responds to changes and external
signals. As such, these findings suggest that targeting such a genetic program within
Plasmodium and preventing its implementation could prove an
effective strategy to curb the spread of malaria. DOI:http://dx.doi.org/10.7554/eLife.04106.002
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Affiliation(s)
- Florence Caro
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Vida Ahyong
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Miguel Betegon
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Joseph L DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
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High guanidinium permeability reveals dehydration-dependent ion selectivity in the plasmodial surface anion channel. BIOMED RESEARCH INTERNATIONAL 2014; 2014:741024. [PMID: 25243175 PMCID: PMC4160636 DOI: 10.1155/2014/741024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/19/2014] [Accepted: 07/23/2014] [Indexed: 11/17/2022]
Abstract
Malaria parasites grow within vertebrate erythrocytes and increase host cell permeability to access nutrients from plasma. This increase is mediated by the plasmodial surface anion channel (PSAC), an unusual ion channel linked to the conserved clag gene family. Although PSAC recognizes and transports a broad range of uncharged and charged solutes, it must efficiently exclude the small Na+ ion to maintain infected cell osmotic stability. Here, we examine possible mechanisms for this remarkable solute selectivity. We identify guanidinium as an organic cation with high permeability into human erythrocytes infected with Plasmodium falciparum, but negligible uptake by uninfected cells. Transport characteristics and pharmacology indicate that this uptake is specifically mediated by PSAC. The rank order of organic and inorganic cation permeabilities suggests cation dehydration as the rate-limiting step in transport through the channel. The high guanidinium permeability of infected cells also allows rapid and stringent synchronization of parasite cultures, as required for molecular and cellular studies of this pathogen. These studies provide important insights into how nutrients and ions are transported via PSAC, an established target for antimalarial drug development.
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Jain SA, Basu H, Prabhu PS, Soni U, Joshi MD, Mathur D, Patravale VB, Pathak S, Sharma S. Parasite impairment by targeting Plasmodium-infected RBCs using glyceryl-dilaurate nanostructured lipid carriers. Biomaterials 2014; 35:6636-45. [DOI: 10.1016/j.biomaterials.2014.04.058] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/16/2014] [Indexed: 12/30/2022]
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29
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Cheemadan S, Ramadoss R, Bozdech Z. Role of calcium signaling in the transcriptional regulation of the apicoplast genome of Plasmodium falciparum. BIOMED RESEARCH INTERNATIONAL 2014; 2014:869401. [PMID: 24877144 PMCID: PMC4022301 DOI: 10.1155/2014/869401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 12/19/2022]
Abstract
Calcium is a universal second messenger that plays an important role in regulatory processes in eukaryotic cells. To understand calcium-dependent signaling in malaria parasites, we analyzed transcriptional responses of Plasmodium falciparum to two calcium ionophores (A23187 and ionomycin) that cause redistribution of intracellular calcium within the cytoplasm. While ionomycin induced a specific transcriptional response defined by up- or downregulation of a narrow set of genes, A23187 caused a developmental arrest in the schizont stage. In addition, we observed a dramatic decrease of mRNA levels of the transcripts encoded by the apicoplast genome during the exposure of P. falciparum to both calcium ionophores. Neither of the ionophores caused any disruptions to the DNA replication or the overall apicoplast morphology. This suggests that the mRNA downregulation reflects direct inhibition of the apicoplast gene transcription. Next, we identify a nuclear encoded protein with a calcium binding domain (EF-hand) that is localized to the apicoplast. Overexpression of this protein (termed PfACBP1) in P. falciparum cells mediates an increased resistance to the ionophores which suggests its role in calcium-dependent signaling within the apicoplast. Our data indicate that the P. falciparum apicoplast requires calcium-dependent signaling that involves a novel protein PfACBP1.
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Affiliation(s)
- Sabna Cheemadan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Ramya Ramadoss
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
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30
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Subudhi AK, Boopathi PA, Garg S, Middha S, Acharya J, Pakalapati D, Saxena V, Aiyaz M, Orekondy HB, Mugasimangalam RC, Sirohi P, Kochar SK, Kochar DK, Das A. Natural antisense transcripts in Plasmodium falciparum isolates from patients with complicated malaria. Exp Parasitol 2014; 141:39-54. [PMID: 24657575 DOI: 10.1016/j.exppara.2014.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 02/17/2014] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
Abstract
Mechanisms regulating gene expression in malaria parasites are not well understood. Little is known about how the parasite regulates its gene expression during transition from one developmental stage to another and in response to various environmental conditions. Parasites in a diseased host face environments which differ from the static, well adapted in vitro conditions. Parasites thus need to adapt quickly and effectively to these conditions by establishing transcriptional states which are best suited for better survival. With the discovery of natural antisense transcripts (NATs) in this parasite and considering the various proposed mechanisms by which NATs might regulate gene expression, it has been speculated that these might be playing a critical role in gene regulation. We report here the diversity of NATs in this parasite, using isolates taken directly from patients with differing clinical symptoms caused by malaria infection. Using a custom designed strand specific whole genome microarray, a total of 797 NATs targeted against annotated loci have been detected. Out of these, 545 NATs are unique to this study. The majority of NATs were positively correlated with the expression pattern of the sense transcript. However, 96 genes showed a change in sense/antisense ratio on comparison between uncomplicated and complicated disease conditions. The antisense transcripts map to a broad range of biochemical/metabolic pathways, especially pathways pertaining to the central carbon metabolism and stress related pathways. Our data strongly suggests that a large group of NATs detected here are unannotated transcription units antisense to annotated gene models. The results reveal a previously unknown set of NATs that prevails in this parasite, their differential regulation in disease conditions and mapping to functionally well annotated genes. The results detailed here call for studies to deduce the possible mechanism of action of NATs, which would further help in understanding the in vivo pathological adaptations of these parasites.
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Affiliation(s)
- Amit Kumar Subudhi
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
| | - P A Boopathi
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
| | - Shilpi Garg
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
| | - Sheetal Middha
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India.
| | - Jyoti Acharya
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India.
| | - Deepak Pakalapati
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
| | - Vishal Saxena
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
| | | | | | | | - Paramendra Sirohi
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India.
| | - Sanjay K Kochar
- Department of Medicine, S.P. Medical College, Bikaner, Rajasthan, India.
| | - Dhanpat K Kochar
- Rajasthan University of Health Sciences, Jaipur, Rajasthan, India.
| | - Ashis Das
- Department of Biological Sciences, Birla Institute of Technology and Science (BITS), Pilani, Rajasthan, India.
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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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32
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Li J, Yuan J, Cheng KCC, Inglese J, Su XZ. Chemical genomics for studying parasite gene function and interaction. Trends Parasitol 2013; 29:603-11. [PMID: 24215777 DOI: 10.1016/j.pt.2013.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/08/2013] [Accepted: 10/08/2013] [Indexed: 12/20/2022]
Abstract
With the development of new technologies in genome sequencing, gene expression profiling, genotyping, and high-throughput screening of chemical compound libraries, small molecules are playing increasingly important roles in studying gene expression regulation, gene-gene interaction, and gene function. Here we briefly review and discuss some recent advancements in drug target identification and phenotype characterization using combinations of high-throughput screening of small-molecule libraries and various genome-wide methods such as whole-genome sequencing, genome-wide association studies (GWAS), and genome-wide expression analysis. These approaches can be used to search for new drugs against parasite infections, to identify drug targets or drug resistance genes, and to infer gene function.
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Affiliation(s)
- Jian Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, P.R. China
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33
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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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34
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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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35
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Das S, Basu H, Korde R, Tewari R, Sharma S. Arrest of nuclear division in Plasmodium through blockage of erythrocyte surface exposed ribosomal protein P2. PLoS Pathog 2012; 8:e1002858. [PMID: 22912579 PMCID: PMC3415463 DOI: 10.1371/journal.ppat.1002858] [Citation(s) in RCA: 21] [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: 02/14/2012] [Accepted: 06/27/2012] [Indexed: 12/24/2022] Open
Abstract
Malaria parasites reside inside erythrocytes and the disease manifestations are linked to the growth inside infected erythrocytes (IE). The growth of the parasite is mostly confined to the trophozoite stage during which nuclear division occurs followed by the formation of cell bodies (schizogony). The mechanism and regulation of schizogony are poorly understood. Here we show a novel role for a Plasmodium falciparum 60S stalk ribosomal acidic protein P2 (PfP2) (PFC0400w), which gets exported to the IE surface for 6-8 hrs during early schizogony, starting around 26-28 hrs post-merozoite invasion. The surface exposure is demonstrated using multiple PfP2-specific monoclonal antibodies, and is confirmed through transfection using PfP2-GFP. The IE surface-exposed PfP2-protein occurs mainly as SDS-resistant P2-homo-tetramers. Treatment with anti-PfP2 monoclonals causes arrest of IEs at the first nuclear division. Upon removal of the antibodies, about 80-85% of synchronized parasites can be released even after 24 hrs of antibody treatment. It has been reported that a tubovesicular network (TVN) is set up in early trophozoites which is used for nutrient import. Anti-P2 monoclonal antibodies cause a complete fragmentation of TVN by 36 hrs, and impairs lipid import in IEs. These may be downstream causes for the cell-cycle arrest. Upon antibody removal, the TVN is reconstituted, and the cell division progresses. Each of the above properties is observed in the rodent malaria parasite species P. yoelii and P. berghei. The translocation of the P2 protein to the IE surface is therefore likely to be of fundamental importance in Plasmodium cell division.
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Affiliation(s)
- Sudipta Das
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Himanish Basu
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Reshma Korde
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Rita Tewari
- Centre for Genetics and Genomics, Queen's Medical Centre, The University of Nottingham, Nottingham, United Kingdom
| | - Shobhona Sharma
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
- * E-mail:
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36
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Auliff AM, Balu B, Chen N, O’Neil MT, Cheng Q, Adams JH. Functional analysis of Plasmodium vivax dihydrofolate reductase-thymidylate synthase genes through stable transformation of Plasmodium falciparum. PLoS One 2012; 7:e40416. [PMID: 22792308 PMCID: PMC3392216 DOI: 10.1371/journal.pone.0040416] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/07/2012] [Indexed: 12/02/2022] Open
Abstract
Mechanisms of drug resistance in Plasmodium vivax have been difficult to study partially because of the difficulties in culturing the parasite in vitro. This hampers monitoring drug resistance and research to develop or evaluate new drugs. There is an urgent need for a novel method to study mechanisms of P. vivax drug resistance. In this paper we report the development and application of the first Plasmodium falciparum expression system to stably express P. vivax dhfr-ts alleles. We used the piggyBac transposition system for the rapid integration of wild-type, single mutant (117N) and quadruple mutant (57L/58R/61M/117T) pvdhfr-ts alleles into the P. falciparum genome. The majority (81%) of the integrations occurred in non-coding regions of the genome; however, the levels of pvdhfr transcription driven by the P. falciparum dhfr promoter were not different between integrants of non-coding and coding regions. The integrated quadruple pvdhfr mutant allele was much less susceptible to antifolates than the wild-type and single mutant pvdhfr alleles. The resistance phenotype was stable without drug pressure. All the integrated clones were susceptible to the novel antifolate JPC-2067. Therefore, the piggyBac expression system provides a novel and important tool to investigate drug resistance mechanisms and gene functions in P. vivax.
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Affiliation(s)
- Alyson M. Auliff
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
- School of Population Health, University of Queensland, Brisbane, Queensland, Australia
| | - Bharath Balu
- Department of Global Health, University of South Florida, Tampa, Florida, United States of America
| | - Nanhua Chen
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
| | - Michael T. O’Neil
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Qin Cheng
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
- School of Population Health, University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (JHA); (QC)
| | - John H. Adams
- Department of Global Health, University of South Florida, Tampa, Florida, United States of America
- * E-mail: (JHA); (QC)
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37
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Balu B. Moving "Forward" in Plasmodium Genetics through a Transposon-Based Approach. J Trop Med 2012; 2012:829210. [PMID: 22649460 PMCID: PMC3356940 DOI: 10.1155/2012/829210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 02/07/2012] [Accepted: 02/20/2012] [Indexed: 01/07/2023] Open
Abstract
The genome sequence of the human malaria parasite, Plasmodium falciparum, was released almost a decade ago. A majority of the Plasmodium genome, however, remains annotated to code for hypothetical proteins with unknown functions. The introduction of forward genetics has provided novel means to gain a better understanding of gene functions and their associated phenotypes in Plasmodium. Even with certain limitations, the technique has already shown significant promise to increase our understanding of parasite biology needed for rationalized drug and vaccine design. Further improvements to the mutagenesis technique and the design of novel genetic screens should lead us to some exciting discoveries about the critical weaknesses of Plasmodium, and greatly aid in the development of new disease intervention strategies.
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Affiliation(s)
- Bharath Balu
- Tropical Disease Research Program, Center for Infectious Disease and Biodefense Research, SRI International, Harrisonburg, VA 22802, USA
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38
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Rovira-Graells N, Gupta AP, Planet E, Crowley VM, Mok S, Ribas de Pouplana L, Preiser PR, Bozdech Z, Cortés A. Transcriptional variation in the malaria parasite Plasmodium falciparum. Genome Res 2012; 22:925-38. [PMID: 22415456 PMCID: PMC3337437 DOI: 10.1101/gr.129692.111] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Malaria genetic variation has been extensively characterized, but the level of epigenetic plasticity remains largely unexplored. Here we provide a comprehensive characterization of transcriptional variation in the most lethal malaria parasite, Plasmodium falciparum, based on highly accurate transcriptional analysis of isogenic parasite lines grown under homogeneous conditions. This analysis revealed extensive transcriptional heterogeneity within genetically homogeneous clonal parasite populations. We show that clonally variant expression controlled at the epigenetic level is an intrinsic property of specific genes and gene families, the majority of which participate in host–parasite interactions. Intrinsic transcriptional variability is not restricted to genes involved in immune evasion, but also affects genes linked to lipid metabolism, protein folding, erythrocyte remodeling, or transcriptional regulation, among others, indicating that epigenetic variation results in both antigenic and functional variation. We observed a general association between heterochromatin marks and clonally variant expression, extending previous observations for specific genes to essentially all variantly expressed gene families. These results suggest that phenotypic variation of functionally unrelated P. falciparum gene families is mediated by a common mechanism based on reversible formation of H3K9me3-based heterochromatin. In changing environments, diversity confers fitness to a population. Our results support the idea that P. falciparum uses a bet-hedging strategy, as an alternative to directed transcriptional responses, to adapt to common fluctuations in its environment. Consistent with this idea, we found that transcriptionally different isogenic parasite lines markedly differed in their survival to heat-shock mimicking febrile episodes and adapted to periodic heat-shock with a pattern consistent with natural selection of pre-existing parasites.
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39
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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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40
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Deficiency of a Niemann-Pick, type C1-related protein in toxoplasma is associated with multiple lipidoses and increased pathogenicity. PLoS Pathog 2011; 7:e1002410. [PMID: 22174676 PMCID: PMC3234224 DOI: 10.1371/journal.ppat.1002410] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 10/16/2011] [Indexed: 02/07/2023] Open
Abstract
Several proteins that play key roles in cholesterol synthesis, regulation, trafficking and signaling are united by sharing the phylogenetically conserved 'sterol-sensing domain' (SSD). The intracellular parasite Toxoplasma possesses at least one gene coding for a protein containing the canonical SSD. We investigated the role of this protein to provide information on lipid regulatory mechanisms in the parasite. The protein sequence predicts an uncharacterized Niemann-Pick, type C1-related protein (NPC1) with significant identity to human NPC1, and it contains many residues implicated in human NPC disease. We named this NPC1-related protein, TgNCR1. Mammalian NPC1 localizes to endo-lysosomes and promotes the movement of sterols and sphingolipids across the membranes of these organelles. Miscoding patient mutations in NPC1 cause overloading of these lipids in endo-lysosomes. TgNCR1, however, lacks endosomal targeting signals, and localizes to flattened vesicles beneath the plasma membrane of Toxoplasma. When expressed in mammalian NPC1 mutant cells and properly addressed to endo-lysosomes, TgNCR1 restores cholesterol and GM1 clearance from these organelles. To clarify the role of TgNCR1 in the parasite, we genetically disrupted NCR1; mutant parasites were viable. Quantitative lipidomic analyses on the ΔNCR1 strain reveal normal cholesterol levels but an overaccumulation of several species of cholesteryl esters, sphingomyelins and ceramides. ΔNCR1 parasites are also characterized by abundant storage lipid bodies and long membranous tubules derived from their parasitophorous vacuoles. Interestingly, these mutants can generate multiple daughters per single mother cell at high frequencies, allowing fast replication in vitro, and they are slightly more virulent in mice than the parental strain. These data suggest that the ΔNCR1 strain has lost the ability to control the intracellular levels of several lipids, which subsequently results in the stimulation of lipid storage, membrane biosynthesis and parasite division. Based on these observations, we ascribe a role for TgNCR1 in lipid homeostasis in Toxoplasma.
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41
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McNamara C, Winzeler EA. Target identification and validation of novel antimalarials. Future Microbiol 2011; 6:693-704. [PMID: 21707315 DOI: 10.2217/fmb.11.45] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been recognized that new antimalarials with a novel mode of action are critical to combat the continued emergence and dissemination of drug-resistant parasites that threaten the efficacy of current malaria treatments. Thus, recent high-throughput screening campaigns have been initiated using asexual intraerythrocytic stage cell-based assays of Plasmodium falciparum. These have led to the unprecedented identification of over 10,000 new antimalarial compounds. Inherently, novel compounds identified by cell-based assays will have poorly defined modes of action. While some of these compounds may have recognizable targets, the majority of cell-based hits are comprised of unique chemical scaffolds usually lacking cross-resistance with known drugs. It is likely that these novel antimalarial scaffolds will reveal new targets. A challenge for the community will be to assign these small molecules to their targets. In this article, we review methodologies to assist in the determination of a compound's mode of action.
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Affiliation(s)
- Case McNamara
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121, USA
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Melcher M, Muhle RA, Henrich PP, Kraemer SM, Avril M, Vigan-Womas I, Mercereau-Puijalon O, Smith JD, Fidock DA. Identification of a role for the PfEMP1 semi-conserved head structure in protein trafficking to the surface of Plasmodium falciparum infected red blood cells. Cell Microbiol 2010; 12:1446-62. [PMID: 20438573 DOI: 10.1111/j.1462-5822.2010.01481.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transport of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) variants to the red blood cell (RBC) surface enables malarial parasite evasion of host immunity by modifying the antigenic and adhesive properties of infected RBCs. In this study, we applied the Bxb1 integrase system to integrate transgenes encoding truncated PfEMP1-GFP fusions into cytoadherent A4 parasites and characterize their surface transport requirements. Our studies revealed that the semi-conserved head structure of PfEMP1 proteins, in combination with the predicted transmembrane region and cytoplasmic tail, encodes sufficient information for RBC surface display. In contrast, miniPfEMP1 proteins with truncated head structures were exported to the RBC cytoplasm but were not detected at the RBC surface by flow cytometry or immuno-electron microscopy. We demonstrated the absence of a mechanistic barrier to having native and miniPfEMP1 proteins displayed simultaneously at the RBC surface. However, surface-exposed miniPfEMP1 proteins did not convey cytoadherence properties to their host cells, implicating potential steric considerations in host-receptor interactions or the need for multiple domains to mediate cell binding. This study establishes a new system to investigate PfEMP1 transport and demonstrates that the PfEMP1 semi-conserved head structure is under selection for protein transport, in addition to its known roles in adhesion.
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Affiliation(s)
- Martin Melcher
- Seattle Biomedical Research Institute, Seattle, WA, 98109, USA
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Dhangadamajhi G, Kar SK, Ranjit M. The survival strategies of malaria parasite in the red blood cell and host cell polymorphisms. Malar Res Treat 2010; 2010:973094. [PMID: 22332025 PMCID: PMC3277829 DOI: 10.4061/2010/973094] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 07/07/2010] [Indexed: 11/20/2022] Open
Abstract
Parasite growth within the erythrocyte causes dramatic alterations of host cell which on one hand facilitates nutrients acquisition from extracellular environment and on other hand contributes to the symptoms of severe malaria. The current paper focuses on interactions between the Plasmodium parasite and its metabolically highly reduced host cell, the natural selection of numerous polymorphisms in the genes encoding hemoglobin and other erythrocyte proteins.
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Affiliation(s)
- Gunanidhi Dhangadamajhi
- Regional Medical Research Centre, Indian Council of Medical Research, Chandrasekharpur, Bhubaneswar 751023, India
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Hanssen E, McMillan PJ, Tilley L. Cellular architecture of Plasmodium falciparum-infected erythrocytes. Int J Parasitol 2010; 40:1127-35. [DOI: 10.1016/j.ijpara.2010.04.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 04/15/2010] [Accepted: 04/15/2010] [Indexed: 01/11/2023]
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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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Becker JVW, Mtwisha L, Crampton BG, Stoychev S, van Brummelen AC, Reeksting S, Louw AI, Birkholtz LM, Mancama DT. Plasmodium falciparum spermidine synthase inhibition results in unique perturbation-specific effects observed on transcript, protein and metabolite levels. BMC Genomics 2010; 11:235. [PMID: 20385001 PMCID: PMC2867828 DOI: 10.1186/1471-2164-11-235] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 04/12/2010] [Indexed: 12/02/2022] Open
Abstract
Background Plasmodium falciparum, the causative agent of severe human malaria, has evolved to become resistant to previously successful antimalarial chemotherapies, most notably chloroquine and the antifolates. The prevalence of resistant strains has necessitated the discovery and development of new chemical entities with novel modes-of-action. Although much effort has been invested in the creation of analogues based on existing drugs and the screening of chemical and natural compound libraries, a crucial shortcoming in current Plasmodial drug discovery efforts remains the lack of an extensive set of novel, validated drug targets. A requirement of these targets (or the pathways in which they function) is that they prove essential for parasite survival. The polyamine biosynthetic pathway, responsible for the metabolism of highly abundant amines crucial for parasite growth, proliferation and differentiation, is currently under investigation as an antimalarial target. Chemotherapeutic strategies targeting this pathway have been successfully utilized for the treatment of Trypanosomes causing West African sleeping sickness. In order to further evaluate polyamine depletion as possible antimalarial intervention, the consequences of inhibiting P. falciparum spermidine synthase (PfSpdSyn) were examined on a morphological, transcriptomic, proteomic and metabolic level. Results Morphological analysis of P. falciparum 3D7 following application of the PfSpdSyn inhibitor cyclohexylamine confirmed that parasite development was completely arrested at the early trophozoite stage. This is in contrast to untreated parasites which progressed to late trophozoites at comparable time points. Global gene expression analyses confirmed a transcriptional arrest in the parasite. Several of the differentially expressed genes mapped to the polyamine biosynthetic and associated metabolic pathways. Differential expression of corresponding parasite proteins involved in polyamine biosynthesis was also observed. Most notably, uridine phosphorylase, adenosine deaminase, lysine decarboxylase (LDC) and S-adenosylmethionine synthetase were differentially expressed at the transcript and/or protein level. Several genes in associated metabolic pathways (purine metabolism and various methyltransferases) were also affected. The specific nature of the perturbation was additionally reflected by changes in polyamine metabolite levels. Conclusions This study details the malaria parasite's response to PfSpdSyn inhibition on the transcriptomic, proteomic and metabolic levels. The results corroborate and significantly expand previous functional genomics studies relating to polyamine depletion in this parasite. Moreover, they confirm the role of transcriptional regulation in P. falciparum, particularly in this pathway. The findings promote this essential pathway as a target for antimalarial chemotherapeutic intervention strategies.
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Coppens I, Sullivan DJ, Prigge ST. An update on the rapid advances in malaria parasite cell biology. Trends Parasitol 2010; 26:305-10. [PMID: 20382563 DOI: 10.1016/j.pt.2010.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 03/10/2010] [Accepted: 03/12/2010] [Indexed: 01/05/2023]
Abstract
Recent years have seen rapid advances in our understanding of malaria parasite cell biology. Some of this progress has been the result of developments in genetic techniques, advances in imaging technology, and new molecular tools. We focus on three aspects of parasite cell biology: (i) plastid metabolism, (ii) sporozoite biology, and (iii) protein transport to and from the host erythrocyte. In each case recent work has led to a deeper understanding of parasite biology, often at the expense of previously accepted paradigms. These studies also highlight the impediments, technical and otherwise, that will have to be overcome for continued rapid progress in these fields.
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Affiliation(s)
- Isabelle Coppens
- Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Abstract
In order to survive and promote its virulence the malaria parasite must export hundreds of its proteins beyond an encasing vacuole and membrane into the host red blood cell. In the last few years, several major advances have been made that have significantly contributed to our understanding of this export process. These include: (i) the identification of sequences that direct protein export (a signal sequence and a motif termed PEXEL), which have allowed predictions of the exportomes of Plasmodium species that are the cause of malaria, (ii) the recognition that the fate of proteins destined for export is already decided within the parasite's endoplasmic reticulum and involves the PEXEL motif being recognized and cleaved by the aspartic protease plasmepsin V and (iii) the discovery of the Plasmodium translocon of exported proteins (PTEX) that is responsible for the passage of proteins across the vacuolar membrane. We review protein export in Plasmodium and these latest developments in the field that have now provided a new platform from which trafficking of malaria proteins can be dissected.
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Affiliation(s)
- Silvia Haase
- Strategic Research Centre for Molecular and Medical Research, Deakin University, Waurn Ponds, Vic., Australia
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Transcriptional profiling of growth perturbations of the human malaria parasite Plasmodium falciparum. Nat Biotechnol 2009; 28:91-8. [PMID: 20037583 DOI: 10.1038/nbt.1597] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 12/06/2009] [Indexed: 12/25/2022]
Abstract
Functions have yet to be defined for the majority of genes of Plasmodium falciparum, the agent responsible for the most serious form of human malaria. Here we report changes in P. falciparum gene expression induced by 20 compounds that inhibit growth of the schizont stage of the intraerythrocytic development cycle. In contrast with previous studies, which reported only minimal changes in response to chemically induced perturbations of P. falciparum growth, we find that approximately 59% of its coding genes display over three-fold changes in expression in response to at least one of the chemicals we tested. We use this compendium for guilt-by-association prediction of protein function using an interaction network constructed from gene co-expression, sequence homology, domain-domain and yeast two-hybrid data. The subcellular localizations of 31 of 42 proteins linked with merozoite invasion is consistent with their role in this process, a key target for malaria control. Our network may facilitate identification of novel antimalarial drugs and vaccines.
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Sam-Yellowe TY. The role of the Maurer's clefts in protein transport in Plasmodium falciparum. Trends Parasitol 2009; 25:277-84. [PMID: 19442584 DOI: 10.1016/j.pt.2009.03.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 01/15/2009] [Accepted: 03/20/2009] [Indexed: 10/20/2022]
Abstract
Maurer's clefts (MCs) are membranous structures that are formed by Plasmodium falciparum and used by the parasite for protein sorting and protein export. Virulence proteins, as well as other proteins used to remodel the erythrocyte, are exported. Discontinuity between major membrane compartments within the infected erythrocyte cytoplasm suggests multiple traffic routes for exported proteins. The sequences of the conserved Plasmodium export element seem insufficient for export of all parasite proteins. The parasite displays remarkable versatility in the types of proteins exported to the MCs and in the functions of the proteins within the MCs. In this Review, protein export to the MCs and the role of the MCs in the transport of proteins to the erythrocyte membrane are summarized.
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Affiliation(s)
- Tobili Y Sam-Yellowe
- Department of Biological Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, SI 219, Cleveland, OH 44115, USA.
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