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Mamudu CO, Tebamifor ME, Sule MO, Dokunmu TM, Ogunlana OO, Iheagwam FN. Apicoplast-Resident Processes: Exploiting the Chink in the Armour of Plasmodium falciparum Parasites. Adv Pharmacol Pharm Sci 2024; 2024:9940468. [PMID: 38765186 PMCID: PMC11101256 DOI: 10.1155/2024/9940468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 03/25/2024] [Accepted: 04/20/2024] [Indexed: 05/21/2024] Open
Abstract
The discovery of a relict plastid, also known as an apicoplast (apicomplexan plastid), that houses housekeeping processes and metabolic pathways critical to Plasmodium parasites' survival has prompted increased research on identifying potent inhibitors that can impinge on apicoplast-localised processes. The apicoplast is absent in humans, yet it is proposed to originate from the eukaryote's secondary endosymbiosis of a primary symbiont. This symbiotic relationship provides a favourable microenvironment for metabolic processes such as haem biosynthesis, Fe-S cluster synthesis, isoprenoid biosynthesis, fatty acid synthesis, and housekeeping processes such as DNA replication, transcription, and translation, distinct from analogous mammalian processes. Recent advancements in comprehending the biology of the apicoplast reveal it as a vulnerable organelle for malaria parasites, offering numerous potential targets for effective antimalarial therapies. We provide an overview of the metabolic processes occurring in the apicoplast and discuss the organelle as a viable antimalarial target in light of current advances in drug discovery. We further highlighted the relevance of these metabolic processes to Plasmodium falciparum during the different stages of the lifecycle.
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Affiliation(s)
- Collins Ojonugwa Mamudu
- Department of Biochemistry, Covenant University, Ota, Nigeria
- Covenant Applied Informatics and Communication Africa Centre of Excellence, Ota, Nigeria
| | - Mercy Eyitomi Tebamifor
- Department of Biochemistry, Covenant University, Ota, Nigeria
- Covenant Applied Informatics and Communication Africa Centre of Excellence, Ota, Nigeria
| | - Mary Ohunene Sule
- Confluence University of Science and Technology, Osara, Kogi, Nigeria
| | - Titilope Modupe Dokunmu
- Department of Biochemistry, Covenant University, Ota, Nigeria
- Covenant Applied Informatics and Communication Africa Centre of Excellence, Ota, Nigeria
| | - Olubanke Olujoke Ogunlana
- Department of Biochemistry, Covenant University, Ota, Nigeria
- Covenant Applied Informatics and Communication Africa Centre of Excellence, Ota, Nigeria
- Covenant University Public Health and Wellbeing Research Cluster, Covenant University, Ota, Nigeria
| | - Franklyn Nonso Iheagwam
- Department of Biochemistry, Covenant University, Ota, Nigeria
- Covenant University Public Health and Wellbeing Research Cluster, Covenant University, Ota, Nigeria
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Anaguano D, Adewale-Fasoro O, Vick GS, Yanik S, Blauwkamp J, Fierro MA, Absalon S, Srinivasan P, Muralidharan V. Plasmodium RON11 triggers biogenesis of the merozoite rhoptry pair and is essential for erythrocyte invasion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.29.577654. [PMID: 38352500 PMCID: PMC10862748 DOI: 10.1101/2024.01.29.577654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Malaria is a global and deadly human disease caused by the apicomplexan parasites of the genus Plasmodium. Parasite proliferation within human red blood cells (RBC) is associated with the clinical manifestations of the disease. This asexual expansion within human RBCs, begins with the invasion of RBCs by P. falciparum, which is mediated by the secretion of effectors from two specialized club-shaped secretory organelles in merozoite-stage parasites known as rhoptries. We investigated the function of the Rhoptry Neck Protein 11 (RON11), which contains seven transmembrane domains and calcium-binding EF-hand domains. We generated conditional mutants of the P. falciparum RON11. Knockdown of RON11 inhibits parasite growth by preventing merozoite invasion. The loss of RON11 did not lead to any defects in processing of rhoptry proteins but instead led to a decrease in the amount of rhoptry proteins. We utilized ultrastructure expansion microscopy (U-ExM) to determine the effect of RON11 knockdown on rhoptry biogenesis. Surprisingly, in the absence of RON11, fully developed merozoites had only one rhoptry each. The single rhoptry in RON11 deficient merozoites were morphologically typical with a bulb and a neck oriented into the apical polar ring. Moreover, rhoptry proteins are trafficked accurately to the single rhoptry in RON11 deficient parasites. These data show that in the absence of RON11, the first rhoptry is generated during schizogony but upon the start of cytokinesis, the second rhoptry never forms. Interestingly, these single-rhoptry merozoites were able to attach to host RBCs but are unable to invade RBCs. Instead, RON11 deficient merozoites continue to engage with RBC for prolonged periods eventually resulting in echinocytosis, a result of secreting the contents from the single rhoptry into the RBC. Together, our data show that RON11 triggers the de novo biogenesis of the second rhoptry and functions in RBC invasion.
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Affiliation(s)
- David Anaguano
- Department of Cellular Biology, University of Georgia, Athens, GA
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA
| | - Opeoluwa Adewale-Fasoro
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
- The Johns Hopkins Malaria Research Institute, Baltimore, MD, 21205, USA
| | - Grace S. Vick
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - Sean Yanik
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
- The Johns Hopkins Malaria Research Institute, Baltimore, MD, 21205, USA
| | - James Blauwkamp
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Manuel A. Fierro
- Department of Cellular Biology, University of Georgia, Athens, GA
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis IN
| | - Prakash Srinivasan
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
- The Johns Hopkins Malaria Research Institute, Baltimore, MD, 21205, USA
| | - Vasant Muralidharan
- Department of Cellular Biology, University of Georgia, Athens, GA
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA
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Tomasina R, González FC, Echeverría S, Cabrera A, Robello C. Insights into the Cell Division of Neospora caninum. Microorganisms 2023; 12:61. [PMID: 38257886 PMCID: PMC10818811 DOI: 10.3390/microorganisms12010061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
Neospora caninum is an apicomplexan protozoan parasite responsible for causing neosporosis in a range of animal species. It results in substantial economic losses in the livestock industry and poses significant health risks to companion and wild animals. Central to its survival and pathogenicity is the process of cell division, which remains poorly understood in this parasite. In this study, we explored the cell division of Neospora caninum using a combination of modern and classic imaging tools, emphasizing its pivotal role in perpetuating the parasite's life cycle and contributing to its ability to persist within host organisms. We described the intricacies of endodyogeny in Neospora caninum, detailing the dynamics of the cell assembly and the nuclear division by ultrastructure expansion microscopy and regular confocal microscopy. Furthermore, we explored the centrosome dynamics, the centrioles and the apicoplast through the advancement of the cell cycle. Our analysis described with unprecedented detail, the endodyogeny in this parasite. By advancing our understanding of these molecular mechanisms, we aimed to inspire innovative strategies for disease management and control, with the ultimate goal of mitigating the devastating impact of neosporosis on animal health and welfare.
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Affiliation(s)
- Ramiro Tomasina
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
| | - Fabiana C. González
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
| | - Soledad Echeverría
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
| | - Andrés Cabrera
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
| | - Carlos Robello
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
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Liffner B, Cepeda Diaz AK, Blauwkamp J, Anaguano D, Frolich S, Muralidharan V, Wilson DW, Dvorin JD, Absalon S. Atlas of Plasmodium falciparum intraerythrocytic development using expansion microscopy. eLife 2023; 12:RP88088. [PMID: 38108809 PMCID: PMC10727503 DOI: 10.7554/elife.88088] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023] Open
Abstract
Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample by ~4.5×. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have cataloged 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the outer centriolar plaque and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the outer centriolar plaque until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an association with the outer centriolar plaque during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology.
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Affiliation(s)
- Benjamin Liffner
- Department of Pharmacology and Toxicology, Indiana University School of MedicineIndianapolisUnited States
| | - Ana Karla Cepeda Diaz
- Biological and Biomedical Sciences, Harvard Medical SchoolBostonUnited States
- Division of Infectious Diseases, Boston Children’s HospitalBostonUnited States
| | - James Blauwkamp
- Department of Pharmacology and Toxicology, Indiana University School of MedicineIndianapolisUnited States
| | - David Anaguano
- Center for Tropical and Emerging Global Diseases, University of GeorgiaAthensUnited States
- Department of Cellular Biology, Franklin College of Arts and Sciences, University of GeorgiaAthensUnited States
| | - Sonja Frolich
- Research Centre for Infectious Diseases, School of Biological Sciences, University of AdelaideAdelaideAustralia
- Institute for Photonics and Advanced Sensing, University of AdelaideAdelaideAustralia
| | - Vasant Muralidharan
- Center for Tropical and Emerging Global Diseases, University of GeorgiaAthensUnited States
- Department of Cellular Biology, Franklin College of Arts and Sciences, University of GeorgiaAthensUnited States
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of AdelaideAdelaideAustralia
- Institute for Photonics and Advanced Sensing, University of AdelaideAdelaideAustralia
- Burnet Institute, 85 Commercial RoadMelbourneAustralia
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children’s HospitalBostonUnited States
- Department of Pediatrics, Harvard Medical SchoolBostonUnited States
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of MedicineIndianapolisUnited States
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5
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Liffner B, Cepeda Diaz AK, Blauwkamp J, Anaguano D, Frölich S, Muralidharan V, Wilson DW, Dvorin J, Absalon S. Atlas of Plasmodium falciparum intraerythrocytic development using expansion microscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.22.533773. [PMID: 36993606 PMCID: PMC10055389 DOI: 10.1101/2023.03.22.533773] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample ~4.5x. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three-dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have catalogued 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the outer centriolar plaque and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the outer centriolar plaque until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an association with the outer centriolar plaque during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date, and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology.
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Affiliation(s)
- Benjamin Liffner
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ana Karla Cepeda Diaz
- Biological and Biomedical Sciences, Harvard Medical School, Boston MA, USA
- Division of Infectious Diseases, Boston Children’s Hospital, Boston MA, USA
| | - James Blauwkamp
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - David Anaguano
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Department of Cellular Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA
| | - Sonja Frölich
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Vasant Muralidharan
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Department of Cellular Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA
| | - Danny W. Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
- Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, SA, Australia
- Burnet Institute, 85 Commercial Road, Melbourne, VIC, Australia
| | - Jeffrey Dvorin
- Division of Infectious Diseases, Boston Children’s Hospital, Boston MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
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Okada M, Sigala PA. The interdependence of isoprenoid synthesis and apicoplast biogenesis in malaria parasites. PLoS Pathog 2023; 19:e1011713. [PMID: 37883328 PMCID: PMC10602226 DOI: 10.1371/journal.ppat.1011713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023] Open
Abstract
Isoprenoid precursor synthesis is an ancient and fundamental function of plastid organelles and a critical metabolic activity of the apicoplast in Plasmodium malaria parasites [1-3]. Over the past decade, our understanding of apicoplast properties and functions has increased enormously [4], due in large part to our ability to rescue blood-stage parasites from apicoplast-specific dysfunctions by supplementing cultures with isopentenyl pyrophosphate (IPP), a key output of this organelle [5,6]. In this Pearl, we explore the interdependence between isoprenoid metabolism and apicoplast biogenesis in P. falciparum and highlight critical future questions to answer.
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Affiliation(s)
- Megan Okada
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Paul A. Sigala
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States
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7
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Fierro MA, Hussain T, Campin LJ, Beck JR. Knock-sideways by inducible ER retrieval enables a unique approach for studying Plasmodium-secreted proteins. Proc Natl Acad Sci U S A 2023; 120:e2308676120. [PMID: 37552754 PMCID: PMC10433460 DOI: 10.1073/pnas.2308676120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 06/26/2023] [Indexed: 08/10/2023] Open
Abstract
Malaria parasites uniquely depend on protein secretion for their obligate intracellular lifestyle but approaches for dissecting Plasmodium-secreted protein functions are limited. We report knockER, a unique DiCre-mediated knock-sideways approach to sequester secreted proteins in the ER by inducible fusion with a KDEL ER-retrieval sequence. We show conditional ER sequestration of diverse proteins is not generally toxic, enabling loss-of-function studies. We employed knockER in multiple Plasmodium species to interrogate the trafficking, topology, and function of an assortment of proteins that traverse the secretory pathway to diverse compartments including the apicoplast (ClpB1), rhoptries (RON6), dense granules, and parasitophorous vacuole (EXP2, PTEX150, HSP101). Taking advantage of the unique ability to redistribute secreted proteins from their terminal destination to the ER, we reveal that vacuolar levels of the PTEX translocon component HSP101 but not PTEX150 are maintained in excess of what is required to sustain effector protein export into the erythrocyte. Intriguingly, vacuole depletion of HSP101 hypersensitized parasites to a destabilization tag that inhibits HSP101-PTEX complex formation but not to translational knockdown of the entire HSP101 pool, illustrating how redistribution of a target protein by knockER can be used to query function in a compartment-specific manner. Collectively, our results establish knockER as a unique tool for dissecting secreted protein function with subcompartmental resolution that should be widely amenable to genetically tractable eukaryotes.
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Affiliation(s)
- Manuel A. Fierro
- Department of Biomedical Sciences, Iowa State University, Ames, IA50011
| | - Tahir Hussain
- Department of Biomedical Sciences, Iowa State University, Ames, IA50011
| | - Liam J. Campin
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA50011
| | - Josh R. Beck
- Department of Biomedical Sciences, Iowa State University, Ames, IA50011
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA50011
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van Strien J, Evers F, Lutikurti M, Berendsen SL, Garanto A, van Gemert GJ, Cabrera-Orefice A, Rodenburg RJ, Brandt U, Kooij TWA, Huynen MA. Comparative Clustering (CompaCt) of eukaryote complexomes identifies novel interactions and sheds light on protein complex evolution. PLoS Comput Biol 2023; 19:e1011090. [PMID: 37549177 PMCID: PMC10434966 DOI: 10.1371/journal.pcbi.1011090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 08/17/2023] [Accepted: 07/10/2023] [Indexed: 08/09/2023] Open
Abstract
Complexome profiling allows large-scale, untargeted, and comprehensive characterization of protein complexes in a biological sample using a combined approach of separating intact protein complexes e.g., by native gel electrophoresis, followed by mass spectrometric analysis of the proteins in the resulting fractions. Over the last decade, its application has resulted in a large collection of complexome profiling datasets. While computational methods have been developed for the analysis of individual datasets, methods for large-scale comparative analysis of complexomes from multiple species are lacking. Here, we present Comparative Clustering (CompaCt), that performs fully automated integrative analysis of complexome profiling data from multiple species, enabling systematic characterization and comparison of complexomes. CompaCt implements a novel method for leveraging orthology in comparative analysis to allow systematic identification of conserved as well as taxon-specific elements of the analyzed complexomes. We applied this method to a collection of 53 complexome profiles spanning the major branches of the eukaryotes. We demonstrate the ability of CompaCt to robustly identify the composition of protein complexes, and show that integrated analysis of multiple datasets improves characterization of complexes from specific complexome profiles when compared to separate analyses. We identified novel candidate interactors and complexes in a number of species from previously analyzed datasets, like the emp24, the V-ATPase and mitochondrial ATP synthase complexes. Lastly, we demonstrate the utility of CompaCt for the automated large-scale characterization of the complexome of the mosquito Anopheles stephensi shedding light on the evolution of metazoan protein complexes. CompaCt is available from https://github.com/cmbi/compact-bio.
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Affiliation(s)
- Joeri van Strien
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Felix Evers
- Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Madhurya Lutikurti
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Stijn L. Berendsen
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Alejandro Garanto
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Geert-Jan van Gemert
- Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alfredo Cabrera-Orefice
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Pediatrics, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ulrich Brandt
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, the Netherlands
- Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center, Nijmegen, the Netherlands
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Taco W. A. Kooij
- Medical Microbiology, Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martijn A. Huynen
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, the Netherlands
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Catalytic Properties of Caseinolytic Protease Subunit of Plasmodium knowlesi and Its Inhibition by a Member of δ-Lactone, Hyptolide. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123787. [PMID: 35744912 PMCID: PMC9228282 DOI: 10.3390/molecules27123787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/05/2022] [Accepted: 06/08/2022] [Indexed: 11/17/2022]
Abstract
The caseinolytic protease (Clp) system plays an essential role in the protein homeostasis of the malaria parasite, particularly at the stage of apicoplast development. The inhibition of this protein is known to have a lethal effect on the parasite and is therefore considered an interesting avenue for antimalaria drugs discovery. The catalytic activity of the Clp system is modulated by its proteolytic subunit (ClpP), which belongs to the serine protease family member and is therefore extensively studied for further inhibitors development. Among many inhibitors, the group of β-lactone is known to be a specific inhibitor for ClpP. Nevertheless, other groups of lactones have never been studied. This study aims to characterize the catalytic properties of ClpP of Plasmodium knowlesi (Pk-ClpP) and the inhibition properties of a δ-lactone hyptolide against this protein. Accordingly, a codon-optimized synthetic gene encoding Pk-ClpP was expressed in Escherichia coli BL21(DE3) and purified under a single step of Ni2+-affinity chromatography, yielding a 2.20 mg from 1 L culture. Meanwhile, size-exclusion chromatography indicated that Pk-ClpP migrated primarily as homoheptameric with a size of 205 kDa. The specific activity of pure Pk-ClpP was 0.73 U µg-1, with a catalytic efficiency kcat/KM of 0.05 µM-1 s-1, with optimum temperature and pH of 50 °C and 7.0-7.5, respectively. Interestingly, hyptolide, a member of δ-lactone, was shown to inhibit Pk-ClpP with an IC50 value of 17.36 ± 1.44 nM. Structural homology modelling, secondary structure prediction, and far-UV CD spectra revealed that helical structures dominate this protein. In addition, the structural homology modeling showed that this protein forms a barrel-shaped homoheptamer. Docking simulation revealed that the inhibition was found to be a competitive inhibition in which hyptolide was able to dock into the catalytic site and block the substrate. The competitiveness of hyptolide is due to the higher binding affinity of this molecule than the substrate.
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10
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Elaagip A, Absalon S, Florentin A. Apicoplast Dynamics During Plasmodium Cell Cycle. Front Cell Infect Microbiol 2022; 12:864819. [PMID: 35573785 PMCID: PMC9100674 DOI: 10.3389/fcimb.2022.864819] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/11/2022] [Indexed: 11/21/2022] Open
Abstract
The deadly malaria parasite, Plasmodium falciparum, contains a unique subcellular organelle termed the apicoplast, which is a clinically-proven antimalarial drug target. The apicoplast is a plastid with essential metabolic functions that evolved via secondary endosymbiosis. As an ancient endosymbiont, the apicoplast retained its own genome and it must be inherited by daughter cells during cell division. During the asexual replication of P. falciparum inside human red blood cells, both the parasite, and the apicoplast inside it, undergo massive morphological changes, including DNA replication and division. The apicoplast is an integral part of the cell and thus its development is tightly synchronized with the cell cycle. At the same time, certain aspects of its dynamics are independent of nuclear division, representing a degree of autonomy in organelle biogenesis. Here, we review the different aspects of organelle dynamics during P. falciparum intraerythrocytic replication, summarize our current understanding of these processes, and describe the many open questions in this area of parasite basic cell biology.
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Affiliation(s)
- Arwa Elaagip
- Department of Parasitology and Medical Entomology, Faculty of Medical Laboratory Sciences, University of Khartoum, Khartoum, Sudan
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
- *Correspondence: Sabrina Absalon, ; Anat Florentin,
| | - Anat Florentin
- The Kuvin Center for the Study of Infectious and Tropical Diseases, Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
- *Correspondence: Sabrina Absalon, ; Anat Florentin,
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Hollin T, Abel S, Falla A, Pasaje CFA, Bhatia A, Hur M, Kirkwood JS, Saraf A, Prudhomme J, De Souza A, Florens L, Niles JC, Le Roch KG. Functional genomics of RAP proteins and their role in mitoribosome regulation in Plasmodium falciparum. Nat Commun 2022; 13:1275. [PMID: 35277503 PMCID: PMC8917122 DOI: 10.1038/s41467-022-28981-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 02/14/2022] [Indexed: 12/31/2022] Open
Abstract
The RAP (RNA-binding domain abundant in Apicomplexans) protein family has been identified in various organisms. Despite expansion of this protein family in apicomplexan parasites, their main biological functions remain unknown. In this study, we use inducible knockdown studies in the human malaria parasite, Plasmodium falciparum, to show that two RAP proteins, PF3D7_0105200 (PfRAP01) and PF3D7_1470600 (PfRAP21), are essential for parasite survival and localize to the mitochondrion. Using transcriptomics, metabolomics, and proteomics profiling experiments, we further demonstrate that these RAP proteins are involved in mitochondrial RNA metabolism. Using high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (eCLIP-seq), we validate that PfRAP01 and PfRAP21 are true RNA-binding proteins and interact specifically with mitochondrial rRNAs. Finally, mitochondrial enrichment experiments followed by deep sequencing of small RNAs demonstrate that PfRAP21 controls mitochondrial rRNA expression. Collectively, our results establish the role of these RAP proteins in mitoribosome activity and contribute to further understanding this protein family in malaria parasites.
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Affiliation(s)
- Thomas Hollin
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA
| | - Steven Abel
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA
| | - Alejandra Falla
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Anil Bhatia
- Metabolomics Core Facility, University of California, Riverside, CA, 92521, USA
| | - Manhoi Hur
- Metabolomics Core Facility, University of California, Riverside, CA, 92521, USA
| | - Jay S Kirkwood
- Metabolomics Core Facility, University of California, Riverside, CA, 92521, USA
| | - Anita Saraf
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO, 64110, USA
| | - Jacques Prudhomme
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA
| | - Amancio De Souza
- Metabolomics Core Facility, University of California, Riverside, CA, 92521, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO, 64110, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA.
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12
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Cárdenas P, Esherick LY, Chambonnier G, Dey S, Turlo CV, Nasamu AS, Niles JC. GeneTargeter: Automated In Silico Design for Genome Editing in the Malaria Parasite, Plasmodium falciparum. CRISPR J 2022; 5:155-164. [PMID: 35191751 PMCID: PMC8892962 DOI: 10.1089/crispr.2021.0069] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Functional characterization of the multitude of poorly described proteins in the human malarial pathogen, Plasmodium falciparum, requires tools to enable genome-scale perturbation studies. Here, we present GeneTargeter (genetargeter.mit.edu), a software tool for automating the design of homology-directed repair donor vectors to achieve gene knockouts, conditional knockdowns, and epitope tagging of P. falciparum genes. We demonstrate GeneTargeter-facilitated genome-scale design of six different types of knockout and conditional knockdown constructs for the P. falciparum genome and validate the computational design process experimentally with successful donor vector assembly and transfection. The software's modular nature accommodates arbitrary destination vectors and allows customizable designs that extend the genome manipulation outcomes attainable in Plasmodium and other organisms.
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Affiliation(s)
- Pablo Cárdenas
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lisl Y. Esherick
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gaël Chambonnier
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sumanta Dey
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Christopher V. Turlo
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Armiyaw Sebastian Nasamu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jacquin C. Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,Address correspondence to: Jacquin C. Niles, MD, PhD, Department of Biological Engineering, Massachusetts Institute of Technology, Room 56-341, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA,
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13
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Brötz-Oesterhelt H, Vorbach A. Reprogramming of the Caseinolytic Protease by ADEP Antibiotics: Molecular Mechanism, Cellular Consequences, Therapeutic Potential. Front Mol Biosci 2021; 8:690902. [PMID: 34109219 PMCID: PMC8182300 DOI: 10.3389/fmolb.2021.690902] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022] Open
Abstract
Rising antibiotic resistance urgently calls for the discovery and evaluation of novel antibiotic classes and unique antibiotic targets. The caseinolytic protease Clp emerged as an unprecedented target for antibiotic therapy 15 years ago when it was observed that natural product-derived acyldepsipeptide antibiotics (ADEP) dysregulated its proteolytic core ClpP towards destructive proteolysis in bacterial cells. A substantial database has accumulated since on the interaction of ADEP with ClpP, which is comprehensively compiled in this review. On the molecular level, we describe the conformational control that ADEP exerts over ClpP, the nature of the protein substrates degraded, and the emerging structure-activity-relationship of the ADEP compound class. On the physiological level, we review the multi-faceted antibacterial mechanism, species-dependent killing modes, the activity against carcinogenic cells, and the therapeutic potential of the compound class.
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Affiliation(s)
- Heike Brötz-Oesterhelt
- Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tübingen, Germany.,Cluster of Excellence: Controlling Microbes to Fight Infection, Tübingen, Germany
| | - Andreas Vorbach
- Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tübingen, Germany
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14
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Abstract
Malaria, caused by infection with Plasmodium parasites, remains a significant global health concern. For decades, genetic intractability and limited tools hindered our ability to study essential proteins and pathways in Plasmodium falciparum, the parasite associated with the most severe malaria cases. However, recent years have seen major leaps forward in the ability to genetically manipulate P. falciparum parasites and conditionally control protein expression/function. The conditional knockdown systems used in P. falciparum target all 3 components of the central dogma, allowing researchers to conditionally control gene expression, translation, and protein function. Here, we review some of the common knockdown systems that have been adapted or developed for use in P. falciparum. Much of the work done using conditional knockdown approaches has been performed in asexual, blood-stage parasites, but we also highlight their uses in other parts of the life cycle and discuss new ways of applying these systems outside of the intraerythrocytic stages. With the use of these tools, the field’s understanding of parasite biology is ever increasing, and promising new pathways for antimalarial drug development are being discovered.
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15
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Martins-Duarte ÉS, Sheiner L, Reiff SB, de Souza W, Striepen B. Replication and partitioning of the apicoplast genome of Toxoplasma gondii is linked to the cell cycle and requires DNA polymerase and gyrase. Int J Parasitol 2021; 51:493-504. [PMID: 33581138 PMCID: PMC8113025 DOI: 10.1016/j.ijpara.2020.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/30/2020] [Accepted: 11/08/2020] [Indexed: 10/26/2022]
Abstract
Apicomplexans are the causative agents of numerous important infectious diseases including malaria and toxoplasmosis. Most of them harbour a chloroplast-like organelle called the apicoplast that is essential for the parasites' metabolism and survival. While most apicoplast proteins are nuclear encoded, the organelle also maintains its own genome, a 35 kb circle. In this study we used Toxoplasma gondii to identify and characterise essential proteins involved in apicoplast genome replication and to understand how apicoplast genome segregation unfolds over time. We demonstrated that the DNA replication enzymes Prex, DNA gyrase and DNA single stranded binding protein localise to the apicoplast. We show in knockdown experiments that apicoplast DNA Gyrase A and B, and Prex are required for apicoplast genome replication and growth of the parasite. Analysis of apicoplast genome replication by structured illumination microscopy in T. gondii tachyzoites showed that apicoplast nucleoid division and segregation initiate at the beginning of S phase and conclude during mitosis. Thus, the replication and division of the apicoplast nucleoid is highly coordinated with nuclear genome replication and mitosis. Our observations highlight essential components of apicoplast genome maintenance and shed light on the timing of this process in the context of the overall parasite cell cycle.
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Affiliation(s)
- Érica S Martins-Duarte
- Laboratório de Quimioterapia de Protozoários Egler Chiari, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro, RJ, Brazil.
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Sarah B Reiff
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Wanderley de Souza
- Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro, RJ, Brazil; Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Boris Striepen
- Department of Cellular Biology, University of Georgia, Athens, GA, USA; Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA. USA
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16
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Cobb DW, Kudyba HM, Villegas A, Hoopmann MR, Baptista RP, Bruton B, Krakowiak M, Moritz RL, Muralidharan V. A redox-active crosslinker reveals an essential and inhibitable oxidative folding network in the endoplasmic reticulum of malaria parasites. PLoS Pathog 2021; 17:e1009293. [PMID: 33534803 PMCID: PMC7886143 DOI: 10.1371/journal.ppat.1009293] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 02/16/2021] [Accepted: 01/07/2021] [Indexed: 12/18/2022] Open
Abstract
Malaria remains a major global health problem, creating a constant need for research to identify druggable weaknesses in P. falciparum biology. As important components of cellular redox biology, members of the Thioredoxin (Trx) superfamily of proteins have received interest as potential drug targets in Apicomplexans. However, the function and essentiality of endoplasmic reticulum (ER)-localized Trx-domain proteins within P. falciparum has not been investigated. We generated conditional mutants of the protein PfJ2—an ER chaperone and member of the Trx superfamily—and show that it is essential for asexual parasite survival. Using a crosslinker specific for redox-active cysteines, we identified PfJ2 substrates as PfPDI8 and PfPDI11, both members of the Trx superfamily as well, which suggests a redox-regulatory role for PfJ2. Knockdown of these PDIs in PfJ2 conditional mutants show that PfPDI11 may not be essential. However, PfPDI8 is required for asexual growth and our data suggest it may work in a complex with PfJ2 and other ER chaperones. Finally, we show that the redox interactions between these Trx-domain proteins in the parasite ER and their substrates are sensitive to small molecule inhibition. Together these data build a model for how Trx-domain proteins in the P. falciparum ER work together to assist protein folding and demonstrate the suitability of ER-localized Trx-domain proteins for antimalarial drug development. One of the leading and persistent causes of childhood mortality in the world is malaria, which is caused by parasites from the genus Plasmodium. Unfortunately, the parasite has developed resistance to all available drugs, making the discovery of new drug targets and potential small molecule inhibitors of essential parasite biology a top priority. A critical pathway required for many different biological processes in the parasite is oxidative folding which requires members of the Thioredoxin (Trx) superfamily of proteins. But we know almost nothing about the function and essentiality of Trx-domain proteins that localize to the endoplasmic reticulum, the origin of the secretory pathway, within P. falciparum. Here we show that a network of Trx-domain containing proteins function together and are essential for parasite survival within human red blood cells. Further, we identify a small molecule inhibitor of the redox activities of these Trx-domain containing proteins. This study demonstrates the suitability of this pathway for future antimalarial drug development.
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Affiliation(s)
- David W. Cobb
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
| | - Heather M. Kudyba
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
| | - Alejandra Villegas
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
| | - Michael R. Hoopmann
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Rodrigo P. Baptista
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
- Institute of Bioinformatics, University of Georgia, Georgia, United States of America
| | - Baylee Bruton
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
| | - Michelle Krakowiak
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
| | - Robert L. Moritz
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Vasant Muralidharan
- Department of Cellular Biology, University of Georgia, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, United States of America
- * E-mail:
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17
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Bouchnak I, van Wijk KJ. Structure, function, and substrates of Clp AAA+ protease systems in cyanobacteria, plastids, and apicoplasts: A comparative analysis. J Biol Chem 2021; 296:100338. [PMID: 33497624 PMCID: PMC7966870 DOI: 10.1016/j.jbc.2021.100338] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/22/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023] Open
Abstract
ATPases Associated with diverse cellular Activities (AAA+) are a superfamily of proteins that typically assemble into hexameric rings. These proteins contain AAA+ domains with two canonical motifs (Walker A and B) that bind and hydrolyze ATP, allowing them to perform a wide variety of different functions. For example, AAA+ proteins play a prominent role in cellular proteostasis by controlling biogenesis, folding, trafficking, and degradation of proteins present within the cell. Several central proteolytic systems (e.g., Clp, Deg, FtsH, Lon, 26S proteasome) use AAA+ domains or AAA+ proteins to unfold protein substrates (using energy from ATP hydrolysis) to make them accessible for degradation. This allows AAA+ protease systems to degrade aggregates and large proteins, as well as smaller proteins, and feed them as linearized molecules into a protease chamber. This review provides an up-to-date and a comparative overview of the essential Clp AAA+ protease systems in Cyanobacteria (e.g., Synechocystis spp), plastids of photosynthetic eukaryotes (e.g., Arabidopsis, Chlamydomonas), and apicoplasts in the nonphotosynthetic apicomplexan pathogen Plasmodium falciparum. Recent progress and breakthroughs in identifying Clp protease structures, substrates, substrate adaptors (e.g., NblA/B, ClpS, ClpF), and degrons are highlighted. We comment on the physiological importance of Clp activity, including plastid biogenesis, proteostasis, the chloroplast Protein Unfolding Response, and metabolism, across these diverse lineages. Outstanding questions as well as research opportunities and priorities to better understand the essential role of Clp systems in cellular proteostasis are discussed.
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Affiliation(s)
- Imen Bouchnak
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, New York, USA
| | - Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, New York, USA.
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18
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Abstract
Malaria elimination efforts have been repeatedly hindered by the evolution and spread of multidrug-resistant strains of Plasmodium falciparum. The absence of a commercially available vaccine emphasizes the need for a better understanding of Plasmodium biology in order to further translational research. This has been partly facilitated by targeted gene deletion strategies for the functional analysis of parasite genes. However, genes that are essential for parasite replication in erythrocytes are refractory to such methods, and require conditional knockdown or knockout approaches to dissect their function. One such approach is the TetR-DOZI system that employs multiple synthetic aptamers in the untranslated regions of target genes to control their expression in a tetracycline-dependent manner. Maintaining modified parasites with intact aptamer copies has been challenging since these repeats can be lost by recombination. By interspacing the aptamers with unique sequences, we created a stable genetic system that remains effective at controlling target gene expression. One of the most powerful approaches to understanding gene function involves turning genes on and off at will and measuring the impact at the cellular or organismal level. This particularly applies to the cohort of essential genes where traditional gene knockouts are inviable. In Plasmodium falciparum, conditional control of gene expression has been achieved by using multicomponent systems in which individual modules interact with each other to regulate DNA recombination, transcription, or posttranscriptional processes. The recently devised TetR-DOZI aptamer system relies on the ligand-regulatable interaction of a protein module with synthetic RNA aptamers to control the translation of a target gene. This technique has been successfully employed to study essential genes in P. falciparum and involves the insertion of several aptamer copies into the 3′ untranslated regions (UTRs), which provide control over mRNA fate. However, aptamer repeats are prone to recombination and one or more copies can be lost from the system, resulting in a loss of control over target gene expression. We rectified this issue by redesigning the aptamer array to minimize recombination while preserving the control elements. As proof of concept, we compared the original and modified arrays for their ability to knock down the levels of a putative essential apicoplast protein (PF3D7_0815700) and demonstrated that the modified array is highly stable and efficient. This redesign will enhance the utility of a tool that is quickly becoming a favored strategy for genetic studies in P. falciparum. IMPORTANCE Malaria elimination efforts have been repeatedly hindered by the evolution and spread of multidrug-resistant strains of Plasmodium falciparum. The absence of a commercially available vaccine emphasizes the need for a better understanding of Plasmodium biology in order to further translational research. This has been partly facilitated by targeted gene deletion strategies for the functional analysis of parasite genes. However, genes that are essential for parasite replication in erythrocytes are refractory to such methods, and require conditional knockdown or knockout approaches to dissect their function. One such approach is the TetR-DOZI system that employs multiple synthetic aptamers in the untranslated regions of target genes to control their expression in a tetracycline-dependent manner. Maintaining modified parasites with intact aptamer copies has been challenging since these repeats can be lost by recombination. By interspacing the aptamers with unique sequences, we created a stable genetic system that remains effective at controlling target gene expression.
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