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Li ZH, Asady B, Chang L, Hortua Triana MA, Li C, Coppens I, Moreno SNJ. Calcium tunneling through the ER and transfer to other organelles for optimal signaling in Toxoplasma gondii. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.15.608087. [PMID: 39185237 PMCID: PMC11343207 DOI: 10.1101/2024.08.15.608087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Ca 2+ signaling in cells begins with the opening of Ca 2+ channels in either the plasma membrane (PM) or the endoplasmic reticulum (ER) and results in a dramatic increase in the physiologically low (<100 nM) cytosolic Ca 2+ level. The temporal and spatial Ca 2+ levels are well regulated to enable precise and specific activation of critical biological processes. Ca 2+ signaling regulates pathogenic features of apicomplexan parasites like Toxoplasma gondii which infects approximately one-third of the world's population. T. gondii relies on Ca 2+ signals to stimulate traits of its infection cycle and several Ca 2+ signaling elements play essential roles in its parasitic cycle. Active egress, an essential step for the infection cycle of T. gondii is preceded by a large increase in cytosolic Ca 2+ most likely by release from intracellular stores. Intracellular parasites take up Ca 2+ from the host cell during host Ca 2+ signaling events to replenish intracellular stores. In this work, we investigated the mechanism by which intracellular stores are replenished with Ca 2+ and demonstrated a central role for the SERCA-Ca 2+ -ATPase to keep not only the ER filled with Ca 2+ but also acidic stores. We also show mitochondrial Ca 2+ uptake, by transfer of Ca 2+ from the ER most likely through membrane contact sites. We propose a central role for the ER in tunneling of calcium from the extracellular milieu through the ER to other organelles. HIGHLIGHTS The T. gondii ER efficiently takes up Ca 2+ that enters the cytosol from the extracellular milieu. Filling of acidic stores in T. gondii appears to be dependent on the filling of the ER The mitochondrion of T. gondii has no direct access to extracellular calcium but is able to take up Ca 2+ by transfer from the ER and/or acidic stores.
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2
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García-Contreras R, de la Mora J, Mora-Montes HM, Martínez-Álvarez JA, Vicente-Gómez M, Padilla-Vaca F, Vargas-Maya NI, Franco B. The inorganic pyrophosphatases of microorganisms: a structural and functional review. PeerJ 2024; 12:e17496. [PMID: 38938619 PMCID: PMC11210485 DOI: 10.7717/peerj.17496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 05/09/2024] [Indexed: 06/29/2024] Open
Abstract
Pyrophosphatases (PPases) are enzymes that catalyze the hydrolysis of pyrophosphate (PPi), a byproduct of the synthesis and degradation of diverse biomolecules. The accumulation of PPi in the cell can result in cell death. Although the substrate is the same, there are variations in the catalysis and features of these enzymes. Two enzyme forms have been identified in bacteria: cytoplasmic or soluble pyrophosphatases and membrane-bound pyrophosphatases, which play major roles in cell bioenergetics. In eukaryotic cells, cytoplasmic enzymes are the predominant form of PPases (c-PPases), while membrane enzymes (m-PPases) are found only in protists and plants. The study of bacterial cytoplasmic and membrane-bound pyrophosphatases has slowed in recent years. These enzymes are central to cell metabolism and physiology since phospholipid and nucleic acid synthesis release important amounts of PPi that must be removed to allow biosynthesis to continue. In this review, two aims were pursued: first, to provide insight into the structural features of PPases known to date and that are well characterized, and to provide examples of enzymes with novel features. Second, the scientific community should continue studying these enzymes because they have many biotechnological applications. Additionally, in this review, we provide evidence that there are m-PPases present in fungi; to date, no examples have been characterized. Therefore, the diversity of PPase enzymes is still a fruitful field of research. Additionally, we focused on the roles of H+/Na+ pumps and m-PPases in cell bioenergetics. Finally, we provide some examples of the applications of these enzymes in molecular biology and biotechnology, especially in plants. This review is valuable for professionals in the biochemistry field of protein structure-function relationships and experts in other fields, such as chemistry, nanotechnology, and plant sciences.
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Affiliation(s)
- Rodolfo García-Contreras
- Departamento de Microbiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Javier de la Mora
- Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Héctor Manuel Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - José A. Martínez-Álvarez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - Marcos Vicente-Gómez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - Felipe Padilla-Vaca
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - Naurú Idalia Vargas-Maya
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - Bernardo Franco
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
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3
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Docampo R. Advances in the cellular biology, biochemistry, and molecular biology of acidocalcisomes. Microbiol Mol Biol Rev 2024; 88:e0004223. [PMID: 38099688 PMCID: PMC10966946 DOI: 10.1128/mmbr.00042-23] [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] [Indexed: 02/04/2024] Open
Abstract
SUMMARYAcidocalcisomes are organelles conserved during evolution and closely related to the so-called volutin granules of bacteria and archaea, to the acidocalcisome-like vacuoles of yeasts, and to the lysosome-related organelles of animal species. All these organelles have in common their acidity and high content of polyphosphate and calcium. They are characterized by a variety of functions from storage of phosphorus and calcium to roles in Ca2+ signaling, osmoregulation, blood coagulation, and inflammation. They interact with other organelles through membrane contact sites or by fusion, and have several enzymes, pumps, transporters, and channels.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
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4
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Hortua Triana MA, Márquez-Nogueras KM, Fazli MS, Quinn S, Moreno SNJ. Regulation of calcium entry by cyclic GMP signaling in Toxoplasma gondii. J Biol Chem 2024; 300:105771. [PMID: 38382669 PMCID: PMC10959671 DOI: 10.1016/j.jbc.2024.105771] [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: 08/01/2023] [Revised: 01/09/2024] [Accepted: 01/28/2024] [Indexed: 02/23/2024] Open
Abstract
Ca2+ signaling impacts almost every aspect of cellular life. Ca2+ signals are generated through the opening of ion channels that permit the flow of Ca2+ down an electrochemical gradient. Cytosolic Ca2+ fluctuations can be generated through Ca2+ entry from the extracellular milieu or release from intracellular stores. In Toxoplasma gondii, Ca2+ ions play critical roles in several essential functions for the parasite, like invasion of host cells, motility, and egress. Plasma membrane Ca2+ entry in T. gondii was previously shown to be activated by cytosolic calcium and inhibited by the voltage-operated Ca2+ channel blocker nifedipine. However, Ca2+ entry in T. gondii did not show the classical characteristics of store regulation. In this work, we characterized the mechanism by which cytosolic Ca2+ regulates plasma membrane Ca2+ entry in extracellular T. gondii tachyzoites loaded with the Ca2+ indicator Fura-2. We compared the inhibition by nifedipine with the effect of the broad spectrum TRP channel inhibitor, anthranilic acid or ACA, and we find that both inhibitors act on different Ca2+ entry activities. We demonstrate, using pharmacological and genetic tools, that an intracellular signaling pathway engaging cyclic GMP, protein kinase G, Ca2+, and the phosphatidyl inositol phospholipase C affects Ca2+ entry and we present a model for crosstalk between cyclic GMP and cytosolic Ca2+ for the activation of T. gondii's lytic cycle traits.
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Affiliation(s)
- Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | | | | | - Shannon Quinn
- Department of Computer Science, University of Georgia, Athens, Georgia, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA; Department of Cellular Biology, University of Georgia, Athens, Georgia, USA.
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5
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Strauss J, Wilkinson C, Vidilaseris K, de Castro Ribeiro OM, Liu J, Hillier J, Wichert M, Malinen AM, Gehl B, Jeuken LJ, Pearson AR, Goldman A. Functional and structural asymmetry suggest a unifying principle for catalysis in membrane-bound pyrophosphatases. EMBO Rep 2024; 25:853-875. [PMID: 38182815 PMCID: PMC10897367 DOI: 10.1038/s44319-023-00037-x] [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: 08/24/2023] [Revised: 11/27/2023] [Accepted: 12/01/2023] [Indexed: 01/07/2024] Open
Abstract
Membrane-bound pyrophosphatases (M-PPases) are homodimeric primary ion pumps that couple the transport of Na+- and/or H+ across membranes to the hydrolysis of pyrophosphate. Their role in the virulence of protist pathogens like Plasmodium falciparum makes them an intriguing target for structural and functional studies. Here, we show the first structure of a K+-independent M-PPase, asymmetric and time-dependent substrate binding in time-resolved structures of a K+-dependent M-PPase and demonstrate pumping-before-hydrolysis by electrometric studies. We suggest how key residues in helix 12, 13, and the exit channel loops affect ion selectivity and K+-activation due to a complex interplay of residues that are involved in subunit-subunit communication. Our findings not only explain ion selectivity in M-PPases but also why they display half-of-the-sites reactivity. Based on this, we propose, for the first time, a unified model for ion-pumping, hydrolysis, and energy coupling in all M-PPases, including those that pump both Na+ and H+.
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Affiliation(s)
- Jannik Strauss
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
- Numaferm GmbH, Düsseldorf, Germany
| | - Craig Wilkinson
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
| | - Keni Vidilaseris
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - Orquidea M de Castro Ribeiro
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - Jianing Liu
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
| | - James Hillier
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK
- Bio-Rad Laboratories Ltd., Watford, UK
| | - Maximilian Wichert
- Leiden Institute of Chemistry, University Leiden, PO Box 9502, 2300 RA, Leiden, The Netherlands
| | - Anssi M Malinen
- Department of Life Technologies, University of Turku, FIN-20014, Turku, Finland
| | - Bernadette Gehl
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland
- Department of Applied Physics, Aalto University, FI-00076, AALTO, Espoo, Finland
| | - Lars Jc Jeuken
- Leiden Institute of Chemistry, University Leiden, PO Box 9502, 2300 RA, Leiden, The Netherlands
| | - Arwen R Pearson
- Institute for Nanostructure and Solid State Physics, Hamburg Centre for Ultrafast Imaging, Universität Hamburg, 22761, Hamburg, Germany
| | - Adrian Goldman
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, UK.
- Molecular and Integrative Biosciences, Biological and Environmental Sciences, University of Helsinki, 00100, Helsinki, Finland.
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6
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Piro F, Masci S, Kannan G, Focaia R, Schultz TL, Thaprawat P, Carruthers VB, Di Cristina M. A Toxoplasma gondii putative amino acid transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation. mSphere 2024; 9:e0059723. [PMID: 38051073 PMCID: PMC10871165 DOI: 10.1128/msphere.00597-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 10/26/2023] [Indexed: 12/07/2023] Open
Abstract
Toxoplasma gondii is a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. T. gondii possesses a lysosome-like organelle known as the plant-like vacuolar compartment (PLVAC), which serves various functions, including digestion, ion storage and homeostasis, endocytosis, and autophagy. Lysosomes are critical for maintaining cellular health and function by degrading waste materials and recycling components. To supply the cell with the essential building blocks and energy sources required for the maintenance of its functions and structures, the digested solutes generated within the lysosome are transported into the cytosol by proteins embedded in the lysosomal membrane. Currently, a limited number of PLVAC transporters have been characterized, with TgCRT being the sole potential transporter of amino acids and small peptides identified thus far. To bridge this knowledge gap, we used lysosomal amino acid transporters from other organisms as queries to search the T. gondii proteome. This led to the identification of four potential amino acid transporters, which we have designated as TgAAT1-4. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we present preliminary data showing the possible involvement of TgAAT1 in the PLVAC transport of arginine.IMPORTANCEToxoplasma gondii is a highly successful parasite infecting a broad range of warm-blooded organisms, including about one-third of all humans. Although Toxoplasma infections rarely result in symptomatic disease in individuals with a healthy immune system, the incredibly high number of persons infected, along with the risk of severe infection in immunocompromised patients and the potential link of chronic infection to mental disorders, makes this infection a significant public health concern. As a result, there is a pressing need for new treatment approaches that are both effective and well tolerated. The limitations in understanding how Toxoplasma gondii manages its metabolism to adapt to changing environments and triggers its transformation into bradyzoites have hindered the discovery of vulnerabilities in its metabolic pathways or nutrient acquisition mechanisms to identify new therapeutic targets. In this work, we have shown that the lysosome-like organelle plant-like vacuolar compartment (PLVAC), acting through the putative arginine transporter TgAAT1, plays a pivotal role in regulating the parasite's extracellular survival and differentiation into bradyzoites.
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Affiliation(s)
- Federica Piro
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Silvia Masci
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Riccardo Focaia
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Tracey L. Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Pariyamon Thaprawat
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
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7
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Solebo O, Ling L, Nwankwo I, Zhou J, Fu TM, Ke H. Plasmodium falciparum utilizes pyrophosphate to fuel an essential proton pump in the ring stage and the transition to trophozoite stage. PLoS Pathog 2023; 19:e1011818. [PMID: 38048362 PMCID: PMC10732439 DOI: 10.1371/journal.ppat.1011818] [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: 05/25/2023] [Revised: 12/20/2023] [Accepted: 11/10/2023] [Indexed: 12/06/2023] Open
Abstract
During asexual growth and replication cycles inside red blood cells, the malaria parasite Plasmodium falciparum primarily relies on glycolysis for energy supply, as its single mitochondrion performs little or no oxidative phosphorylation. Post merozoite invasion of a host red blood cell, the ring stage lasts approximately 20 hours and was traditionally thought to be metabolically quiescent. However, recent studies have shown that the ring stage is active in several energy-costly processes, including gene transcription, protein translation, protein export, and movement inside the host cell. It has remained unclear whether a low glycolytic flux alone can meet the energy demand of the ring stage over a long period post invasion. Here, we demonstrate that the metabolic by-product pyrophosphate (PPi) is a critical energy source for the development of the ring stage and its transition to the trophozoite stage. During early phases of the asexual development, the parasite utilizes Plasmodium falciparum vacuolar pyrophosphatase 1 (PfVP1), an ancient pyrophosphate-driven proton pump, to export protons across the parasite plasma membrane. Conditional deletion of PfVP1 leads to a delayed ring stage that lasts nearly 48 hours and a complete blockage of the ring-to-trophozoite transition before the onset of parasite death. This developmental arrest can be partially rescued by an orthologous vacuolar pyrophosphatase from Arabidopsis thaliana, but not by the soluble pyrophosphatase from Saccharomyces cerevisiae, which lacks proton pumping activities. Since proton-pumping pyrophosphatases have been evolutionarily lost in human hosts, the essentiality of PfVP1 suggests its potential as an antimalarial drug target. A drug target of the ring stage is highly desired, as current antimalarials have limited efficacy against this stage.
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Affiliation(s)
- Omobukola Solebo
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Liqin Ling
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Ikechukwu Nwankwo
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Jing Zhou
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
- The Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, United States of America
| | - Hangjun Ke
- Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
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8
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Piro F, Masci S, Kannan G, Focaia R, Schultz TL, Carruthers VB, Di Cristina M. A Toxoplasma gondii putative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555807. [PMID: 37693549 PMCID: PMC10491228 DOI: 10.1101/2023.08.31.555807] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Toxoplasma gondii is a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. Most eukaryotes, from yeast to mammals, rely on a nutrient sensing machinery involving the TORC complex as master regulator of cell growth and cell cycle progression. The lysosome functions as a signaling hub where TORC complex assembles and is activated by transceptors, which both sense and transport amino acids, including the arginine transceptor SLC38A9. While most of the TORC components are lost in T. gondii , indicating the evolution of a distinct nutrient sensing mechanism, the parasite's lysosomal plant-like vacuolar compartment (PLVAC) may still serve as a sensory platform for controlling parasite growth and differentiation. Using SLC38A9 to query the T. gondii proteome, we identified four putative amino acid transporters, termed TgAAT1-4, that structurally resemble the SLC38A9 arginine transceptor. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we show that TgAAT1 is involved in the PLVAC efflux of arginine, an amino acid playing a key role in T. gondii differentiation, further supporting the hypothesis that TgAAT1 might play a role in nutrient sensing. IMPORTANCE T. gondii is a highly successful parasite infecting a broad range of warm-blood organisms including about one third of all humans. Although Toxoplasma infections rarely result in symptomatic disease in individuals with a healthy immune system, the incredibly high number of persons infected along with the risk of severe infection in immunocompromised patients and the potential link of chronic infection to mental disorders make this infection a significant public health concern. As a result, there is a pressing need for new treatment approaches that are both effective and well-tolerated. The limitations in understanding how Toxoplasma gondii manages its metabolism to adapt to changing environments and triggers its transformation into bradyzoites have hindered the discovery of vulnerabilities in its metabolic pathways or nutrient acquisition mechanisms to identify new therapeutic targets. In this work, we have shown that the lysosome-like organelle PLVAC, acting through the putative arginine transporter TgAAT1, plays a pivotal role in regulating the parasite's extracellular survival and differentiation into bradyzoites.
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9
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Thornton LB, Key M, Micchelli C, Stasic AJ, Kwain S, Floyd K, Moreno SN, Dominy BN, Whitehead DC, Dou Z. A cathepsin C-like protease mediates the post-translation modification of Toxoplasma gondii secretory proteins for optimal invasion and egress. mBio 2023; 14:e0017423. [PMID: 37326431 PMCID: PMC10470614 DOI: 10.1128/mbio.00174-23] [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: 01/19/2023] [Accepted: 05/01/2023] [Indexed: 06/17/2023] Open
Abstract
Microbial pathogens use proteases for their infections, such as digestion of proteins for nutrients and activation of their virulence factors. As an obligate intracellular parasite, Toxoplasma gondii must invade host cells to establish its intracellular propagation. To facilitate invasion, the parasites secrete invasion effectors from microneme and rhoptry, two unique organelles in apicomplexans. Previous work has shown that some micronemal invasion effectors experience a series of proteolytic cleavages within the parasite's secretion pathway for maturation, such as the aspartyl protease (TgASP3) and the cathepsin L-like protease (TgCPL), localized within the post-Golgi compartment and the endolysosomal system, respectively. Furthermore, it has been shown that the precise maturation of micronemal effectors is critical for Toxoplasma invasion and egress. Here, we show that an endosome-like compartment (ELC)-residing cathepsin C-like protease (TgCPC1) mediates the final trimming of some micronemal effectors, and its loss further results in defects in the steps of invasion, egress, and migration throughout the parasite's lytic cycle. Notably, the deletion of TgCPC1 completely blocks the activation of subtilisin-like protease 1 (TgSUB1) in the parasites, which globally impairs the surface-trimming of many key micronemal invasion and egress effectors. Additionally, we found that Toxoplasma is not efficiently inhibited by the chemical inhibitor targeting the malarial CPC ortholog, suggesting that these cathepsin C-like orthologs are structurally different within the apicomplexan phylum. Collectively, our findings identify a novel function of TgCPC1 in processing micronemal proteins within the Toxoplasma parasite's secretory pathway and expand the understanding of the roles of cathepsin C protease. IMPORTANCE Toxoplasma gondii is a microbial pathogen that is well adapted for disseminating infections. It can infect virtually all warm-blooded animals. Approximately one-third of the human population carries toxoplasmosis. During infection, the parasites sequentially secrete protein effectors from the microneme, rhoptry, and dense granule, three organelles exclusively found in apicomplexan parasites, to help establish their lytic cycle. Proteolytic cleavage of these secretory proteins is required for the parasite's optimal function. Previous work has revealed that two proteases residing within the parasite's secretory pathway cleave micronemal and rhoptry proteins, which mediate parasite invasion and egress. Here, we demonstrate that a cathepsin C-like protease (TgCPC1) is involved in processing several invasion and egress effectors. The genetic deletion of TgCPC1 prevented the complete maturation of some effectors in the parasites. Strikingly, the deletion led to a full inactivation of one surface-anchored protease, which globally impaired the trimming of some key micronemal proteins before secretion. Therefore, this finding represents a novel post-translational mechanism for the processing of virulence factors within microbial pathogens.
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Affiliation(s)
- L. Brock Thornton
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Melanie Key
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Chiara Micchelli
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Andrew J. Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Samuel Kwain
- Department of Chemistry, Clemson University, Clemson, South Carolina, USA
| | - Katherine Floyd
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Silvia N.J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Brian N. Dominy
- Department of Chemistry, Clemson University, Clemson, South Carolina, USA
| | - Daniel C. Whitehead
- Department of Chemistry, Clemson University, Clemson, South Carolina, USA
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, USA
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10
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Wang QQ, Sun M, Tang T, Lai DH, Liu J, Maity S, He K, Wu XT, Yang J, Li YB, Tang XY, Ding HY, Hide G, Distefano M, Lun ZR, Zhu XQ, Long S. Functional screening reveals Toxoplasma prenylated proteins required for endocytic trafficking and rhoptry protein sorting. mBio 2023; 14:e0130923. [PMID: 37548452 PMCID: PMC10470541 DOI: 10.1128/mbio.01309-23] [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: 05/24/2023] [Accepted: 06/12/2023] [Indexed: 08/08/2023] Open
Abstract
In the apicomplexans, endocytosed cargos (e.g., hemoglobin) are trafficked to a specialized organelle for digestion. This follows a unique endocytotic process at the micropore/cytostome in these parasites. However, the mechanism underlying endocytic trafficking remains elusive, due to the repurposing of classical endocytic proteins for the biogenesis of apical organelles. To resolve this issue, we have exploited the genetic tractability of the model apicomplexan Toxoplasma gondii, which ingests host cytosolic materials (e.g., green fluorescent protein[GFP]). We determined an association between protein prenylation and endocytic trafficking, and using an alkyne-labeled click chemistry approach, the prenylated proteome was characterized. Genome editing, using clustered regularly interspaced short palindromic repaet/CRISPR-associated nuclease 9 (CRISPR/Cas9), was efficiently utilized to generate genetically modified lines for the functional screening of 23 prenylated candidates. This identified four of these proteins that regulate the trafficking of endocytosed GFP vesicles. Among these proteins, Rab1B and YKT6.1 are highly conserved but are non-classical endocytic proteins in eukaryotes. Confocal imaging analysis showed that Rab1B and Ras are substantially localized to both the trans-Golgi network and the endosome-like compartments in the parasite. Conditional knockdown of Rab1B caused a rapid defect in secretory trafficking to the rhoptry bulb, suggesting a trafficking intersection role for the key regulator Rab1B. Further experiments confirmed a critical role for protein prenylation in regulating the stability/activity of these proteins (i.e., Rab1B and YKT6.1) in the parasite. Our findings define the molecular basis of endocytic trafficking and reveal a potential intersection function of Rab1B on membrane trafficking in T. gondii. This might extend to other related protists, including the malarial parasites. IMPORTANCE The protozoan Toxoplasma gondii establishes a permissive niche, in host cells, that allows parasites to acquire large molecules such as proteins. Numerous studies have demonstrated that the parasite repurposes the classical endocytic components for secretory sorting to the apical organelles, leaving the question of endocytic transport to the lysosome-like compartment unclear. Recent studies indicated that endocytic trafficking is likely to associate with protein prenylation in malarial parasites. This information promoted us to examine this association in the model apicomplexan T. gondii and to identify the key components of the prenylated proteome that are involved. By exploiting the genetic tractability of T. gondii and a host GFP acquisition assay, we reveal four non-classical endocytic proteins that regulate the transport of endocytosed cargos (e.g., GFP) in T. gondii. Thus, we extend the principle that protein prenylation regulates endocytic trafficking and elucidate the process of non-classical endocytosis in T. gondii and potentially in other related protists.
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Affiliation(s)
- Qiang-Qiang Wang
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Ming Sun
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Tao Tang
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - De-Hua Lai
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jing Liu
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Sanjay Maity
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Kai He
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xi-Ting Wu
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jiong Yang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yue-Bao Li
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiao-Yan Tang
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Hui-Yong Ding
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Geoff Hide
- Biomedical Research and Innovation Centre and Environmental Research and Innovation Centre, School of Science, Engineering and Environment, University of Salford, Salford, United Kingdom
| | - Mark Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Zhao-Rong Lun
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xing-Quan Zhu
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong, Shanxi Province, China
| | - Shaojun Long
- National Key Laboratory of Veterinary Public Health Security and College of Veterinary Medicine, China Agricultural University, Beijing, China
- National Animal Protozoa Laboratory and School of Veterinary Medicine, China Agricultural University, Beijing, China
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11
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Aghabi D, Sloan M, Gill G, Hartmann E, Antipova O, Dou Z, Guerra AJ, Carruthers VB, Harding CR. The vacuolar iron transporter mediates iron detoxification in Toxoplasma gondii. Nat Commun 2023; 14:3659. [PMID: 37339985 PMCID: PMC10281983 DOI: 10.1038/s41467-023-39436-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 06/13/2023] [Indexed: 06/22/2023] Open
Abstract
Iron is essential to cells as a cofactor in enzymes of respiration and replication, however without correct storage, iron leads to the formation of dangerous oxygen radicals. In yeast and plants, iron is transported into a membrane-bound vacuole by the vacuolar iron transporter (VIT). This transporter is conserved in the apicomplexan family of obligate intracellular parasites, including in Toxoplasma gondii. Here, we assess the role of VIT and iron storage in T. gondii. By deleting VIT, we find a slight growth defect in vitro, and iron hypersensitivity, confirming its essential role in parasite iron detoxification, which can be rescued by scavenging of oxygen radicals. We show VIT expression is regulated by iron at transcript and protein levels, and by altering VIT localization. In the absence of VIT, T. gondii responds by altering expression of iron metabolism genes and by increasing antioxidant protein catalase activity. We also show that iron detoxification has an important role both in parasite survival within macrophages and in virulence in a mouse model. Together, by demonstrating a critical role for VIT during iron detoxification in T. gondii, we reveal the importance of iron storage in the parasite and provide the first insight into the machinery involved.
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Affiliation(s)
- Dana Aghabi
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Megan Sloan
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Grace Gill
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Elena Hartmann
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Olga Antipova
- X-Ray Sciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - Alfredo J Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
- Cayman Chemical Company, Ann Arbor, MI, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
| | - Clare R Harding
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
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12
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Thornton LB, Key M, Micchelli C, Stasic AJ, Kwain S, Floyd K, Moreno SNJ, Dominy BN, Whitehead DC, Dou Z. A cathepsin C-like protease post-translationally modifies Toxoplasma gondii secretory proteins for optimal invasion and egress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.21.525043. [PMID: 36712013 PMCID: PMC9882377 DOI: 10.1101/2023.01.21.525043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Microbial pathogens use proteases for their infections, such as digestion of proteins for nutrients and activation of their virulence factors. As an obligate intracellular parasite, Toxoplasma gondii must invade host cells to establish its intracellular propagation. To facilitate invasion, the parasites secrete invasion effectors from microneme and rhoptry, two unique organelles in apicomplexans. Previous work has shown that some micronemal invasion effectors experience a series of proteolytic cleavages within the parasite's secretion pathway for maturation, such as the aspartyl protease (TgASP3) and the cathepsin L-like protease (TgCPL), localized within the post-Golgi compartment (1) and the endolysosomal system (2), respectively. Furthermore, it has been shown that the precise maturation of micronemal effectors is critical for Toxoplasma invasion and egress (1). Here, we show that an endosome-like compartment (ELC)-residing cathepsin C-like protease (TgCPC1) mediates the final trimming of some micronemal effectors, and its loss further results in defects in the steps of invasion, egress, and migration throughout the parasite's lytic cycle. Notably, the deletion of TgCPC1 completely blocks the activation of subtilisin-like protease 1 (TgSUB1) in the parasites, which globally impairs the surface-trimming of many key micronemal invasion and egress effectors. Additionally, we found that TgCPC1 was not efficiently inhibited by the chemical inhibitor targeting its malarial ortholog, suggesting that these cathepsin C-like orthologs are structurally different within the apicomplexan phylum. Taken together, our findings identify a novel function of TgCPC1 in the processing of micronemal proteins within the secretory pathway of Toxoplasma parasites and expand the understanding of the roles of cathepsin C protease. IMPORTANCE Toxoplasma gondii is a microbial pathogen that is well adapted for disseminating infections. It can infect virtually all warm-blooded animals. Approximately one-third of the human population carries toxoplasmosis. During infection, the parasites sequentially secrete protein effectors from the microneme, rhoptry, and dense granule, three organelles exclusively found in apicomplexan parasites, to help establish their lytic cycle. Proteolytic cleavage of these secretory proteins is required for the parasite's optimal function. Previous work has revealed that two proteases residing within the parasite's secretory pathway cleave micronemal and rhoptry proteins, which mediate parasite invasion and egress. Here, we demonstrate that a cathepsin C-like protease (TgCPC1) is involved in processing several invasion and egress effectors. The genetic deletion of TgCPC1 prevented the complete maturation of some effectors in the parasites. Strikingly, the deletion led to a full inactivation of one surface-anchored protease, which globally impaired the trimming of some key micronemal proteins before secretion. Therefore, this finding represents a novel post-translational mechanism for the processing of virulence factors within microbial pathogens.
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Affiliation(s)
- L. Brock Thornton
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Melanie Key
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Chiara Micchelli
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Andrew J. Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Samuel Kwain
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Katherine Floyd
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Brian N. Dominy
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Daniel C. Whitehead
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, United States of America
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, United States of America
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13
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Stasic AJ, Moreno SNJ, Carruthers VB, Dou Z. The Toxoplasma plant-like vacuolar compartment (PLVAC). J Eukaryot Microbiol 2022; 69:e12951. [PMID: 36218001 PMCID: PMC10576567 DOI: 10.1111/jeu.12951] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/28/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. T. gondii shares several characteristics with plants including a nonphotosynthetic plastid termed apicoplast and a multivesicular organelle that was named the plant-like vacuole (PLV) or vacuolar compartment (VAC). The name plant-like vacuole was selected based on its resemblance in composition and function to plant vacuoles. The name VAC represents its general vacuolar characteristics. We will refer to the organelle as PLVAC in this review. New findings in recent years have revealed that the PLVAC represents the lysosomal compartment of T. gondii which has adapted peculiarities to fulfill specific Toxoplasma needs. In this review, we discuss the composition and functions of the PLVAC highlighting its roles in ion storage and homeostasis, endocytosis, exocytosis, and autophagy.
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Affiliation(s)
- Andrew J Stasic
- Department of Microbiology, Heartland FPG, Carmel, Indiana, USA
| | - Silvia N J Moreno
- Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
| | - Vern B Carruthers
- Department of Microbiology & Immunology, University of Michigan Medical School, Michigan, Ann Arbor, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, South Carolina, Clemson, USA
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14
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Holmes AOM, Goldman A, Kalli AC. mPPases create a conserved anionic membrane fingerprint as identified via multi-scale simulations. PLoS Comput Biol 2022; 18:e1010578. [PMID: 36191052 PMCID: PMC9560603 DOI: 10.1371/journal.pcbi.1010578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 10/13/2022] [Accepted: 09/16/2022] [Indexed: 11/06/2022] Open
Abstract
Membrane-integral pyrophosphatases (mPPases) are membrane-bound enzymes responsible for hydrolysing inorganic pyrophosphate and translocating a cation across the membrane. Their function is essential for the infectivity of clinically relevant protozoan parasites and plant maturation. Recent developments have indicated that their mechanism is more complicated than previously thought and that the membrane environment may be important for their function. In this work, we use multiscale molecular dynamics simulations to demonstrate for the first time that mPPases form specific anionic lipid interactions at 4 sites at the distal and interfacial regions of the protein. These interactions are conserved in simulations of the mPPases from Thermotoga maritima, Vigna radiata and Clostridium leptum and characterised by interactions with positive residues on helices 1, 2, 3 and 4 for the distal site, or 9, 10, 13 and 14 for the interfacial site. Due to the importance of these helices in protein stability and function, these lipid interactions may play a crucial role in the mPPase mechanism and enable future structural and functional studies.
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Affiliation(s)
- Alexandra O. M. Holmes
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Adrian Goldman
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
| | - Antreas C. Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
- * E-mail:
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15
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Dave N, LaFavers K, Arrizabalaga G. The Dually Localized EF-Hand Domain-Containing Protein TgEFP1 Regulates the Lytic Cycle of Toxoplasma gondii. Cells 2022; 11:1709. [PMID: 35626745 PMCID: PMC9139715 DOI: 10.3390/cells11101709] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 02/01/2023] Open
Abstract
The propagation of the obligate intracellular parasite Toxoplasma gondii is tightly regulated by calcium signaling. However, the mechanisms by which calcium homeostasis and fluxes are regulated in this human pathogen are not fully understood. To identify Toxoplasma's calcium homeostasis network, we have characterized a novel EF-hand domain-containing protein, which we have named TgEFP1. We have determined that TgEFP1 localizes to a previously described compartment known as the plant-like vacuole or the endosomal-like compartment (PLV/ELC), which harbors several proteins related to ionic regulation. Interestingly, partial permeabilization techniques showed that TgEFP1 is also secreted into the parasitophorous vacuole (PV), within which the parasite divides. Ultrastructure expansion microscopy confirmed the unusual dual localization of TgEFP1 at the PLV/ELC and the PV. Furthermore, we determined that the localization of TgEFP1 to the PV, but not to the PLV/ELC, is affected by disruption of Golgi-dependent transport with Brefeldin A. Knockout of TgEFP1 results in faster propagation in tissue culture, hypersensitivity to calcium ionophore-induced egress, and premature natural egress. Thus, our work has revealed an interplay between the PV and the PLV/ELC and a role for TgEFP1 in the regulation of calcium-dependent events.
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Affiliation(s)
| | | | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (N.D.); (K.L.)
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16
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Johansson NG, Dreano L, Vidilaseris K, Khattab A, Liu J, Lasbleiz A, Ribeiro O, Kiriazis A, Boije af Gennäs G, Meri S, Goldman A, Yli‐Kauhaluoma J, Xhaard H. Exploration of Pyrazolo[1,5-a]pyrimidines as Membrane-Bound Pyrophosphatase Inhibitors. ChemMedChem 2021; 16:3360-3367. [PMID: 34459148 PMCID: PMC8597055 DOI: 10.1002/cmdc.202100392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/03/2021] [Indexed: 11/08/2022]
Abstract
Inhibition of membrane-bound pyrophosphatase (mPPase) with small molecules offer a new approach in the fight against pathogenic protozoan parasites. mPPases are absent in humans, but essential for many protists as they couple pyrophosphate hydrolysis to the active transport of protons or sodium ions across acidocalcisomal membranes. So far, only few nonphosphorus inhibitors have been reported. Here, we explore the chemical space around previous hits using a combination of screening and synthetic medicinal chemistry, identifying compounds with low micromolar inhibitory activities in the Thermotoga maritima mPPase test system. We furthermore provide early structure-activity relationships around a new scaffold having a pyrazolo[1,5-a]pyrimidine core. The most promising pyrazolo[1,5-a]pyrimidine congener was further investigated and found to inhibit Plasmodium falciparum mPPase in membranes as well as the growth of P. falciparum in an ex vivo survival assay.
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Affiliation(s)
- Niklas G. Johansson
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Loïc Dreano
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Keni Vidilaseris
- Department of Biosciences, Division of BiochemistryUniversity of HelsinkiP.O. Box 56 (Viikinkaari 9)00014HelsinkiFinland
| | - Ayman Khattab
- Malaria Research Laboratory, Translational Immunology Research Program, Department of Bacteriology and Immunology, Haartman InstituteUniversity of HelsinkiP.O. Box 21 (Haartmaninkatu 3)00014HelsinkiFinland
| | - Jianing Liu
- Department of Biosciences, Division of BiochemistryUniversity of HelsinkiP.O. Box 56 (Viikinkaari 9)00014HelsinkiFinland
| | - Arthur Lasbleiz
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Orquidea Ribeiro
- Department of Biosciences, Division of BiochemistryUniversity of HelsinkiP.O. Box 56 (Viikinkaari 9)00014HelsinkiFinland
| | - Alexandros Kiriazis
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Gustav Boije af Gennäs
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Seppo Meri
- Malaria Research Laboratory, Translational Immunology Research Program, Department of Bacteriology and Immunology, Haartman InstituteUniversity of HelsinkiP.O. Box 21 (Haartmaninkatu 3)00014HelsinkiFinland
| | - Adrian Goldman
- Department of Biosciences, Division of BiochemistryUniversity of HelsinkiP.O. Box 56 (Viikinkaari 9)00014HelsinkiFinland
- School of Biomedical Sciences and Astbury Centre for Structural Molecular BiologyUniversity of Leeds, Clarendon WayLeeds LS2 9JTUK
| | - Jari Yli‐Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of HelsinkiP.O. Box 56 (Viikinkaari 5 E)00014HelsinkiFinland
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17
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Li ZH, King TP, Ayong L, Asady B, Cai X, Rahman T, Vella SA, Coppens I, Patel S, Moreno SNJ. A plastid two-pore channel essential for inter-organelle communication and growth of Toxoplasma gondii. Nat Commun 2021; 12:5802. [PMID: 34608145 PMCID: PMC8490419 DOI: 10.1038/s41467-021-25987-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/06/2021] [Indexed: 01/04/2023] Open
Abstract
Two-pore channels (TPCs) are a ubiquitous family of cation channels that localize to acidic organelles in animals and plants to regulate numerous Ca2+-dependent events. Little is known about TPCs in unicellular organisms despite their ancient origins. Here, we characterize a TPC from Toxoplasma gondii, the causative agent of toxoplasmosis. TgTPC is a member of a novel clad of TPCs in Apicomplexa, distinct from previously identified TPCs and only present in coccidians. We show that TgTPC localizes not to acidic organelles but to the apicoplast, a non-photosynthetic plastid found in most apicomplexan parasites. Conditional silencing of TgTPC resulted in progressive loss of apicoplast integrity, severely affecting growth and the lytic cycle. Isolation of TPC null mutants revealed a selective role for TPCs in replication independent of apicoplast loss that required conserved residues within the pore-lining region. Using a genetically-encoded Ca2+ indicator targeted to the apicoplast, we show that Ca2+ signals deriving from the ER but not from the extracellular space are selectively transmitted to the lumen. Deletion of the TgTPC gene caused reduced apicoplast Ca2+ uptake and membrane contact site formation between the apicoplast and the ER. Fundamental roles for TPCs in maintaining organelle integrity, inter-organelle communication and growth emerge.
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Affiliation(s)
- Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Thayer P King
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Lawrence Ayong
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Beejan Asady
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Heath, Baltimore, MD, 21205, USA
| | - Xinjiang Cai
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, USA
| | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Heath, Baltimore, MD, 21205, USA
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA. .,Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
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18
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Márquez-Nogueras KM, Hortua Triana MA, Chasen NM, Kuo IY, Moreno SN. Calcium signaling through a transient receptor channel is important for Toxoplasma gondii growth. eLife 2021; 10:63417. [PMID: 34106044 PMCID: PMC8216714 DOI: 10.7554/elife.63417] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 06/08/2021] [Indexed: 12/24/2022] Open
Abstract
Transient receptor potential (TRP) channels participate in calcium ion (Ca2+) influx and intracellular Ca2+ release. TRP channels have not been studied in Toxoplasma gondii or any other apicomplexan parasite. In this work, we characterize TgGT1_310560, a protein predicted to possess a TRP domain (TgTRPPL-2), and determined its role in Ca2+ signaling in T. gondii, the causative agent of toxoplasmosis. TgTRPPL-2 localizes to the plasma membrane and the endoplasmic reticulum (ER) of T. gondii. The ΔTgTRPPL-2 mutant was defective in growth and cytosolic Ca2+ influx from both extracellular and intracellular sources. Heterologous expression of TgTRPPL-2 in HEK-3KO cells allowed its functional characterization. Patching of ER-nuclear membranes demonstrates that TgTRPPL-2 is a non-selective cation channel that conducts Ca2+. Pharmacological blockers of TgTRPPL-2 inhibit Ca2+ influx and parasite growth. This is the first report of an apicomplexan ion channel that conducts Ca2+ and may initiate a Ca2+ signaling cascade that leads to the stimulation of motility, invasion, and egress. TgTRPPL-2 is a potential target for combating toxoplasmosis.
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Affiliation(s)
- Karla Marie Márquez-Nogueras
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States.,Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | | | - Nathan M Chasen
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States
| | - Ivana Y Kuo
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Silvia Nj Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States.,Department of Cellular Biology, University of Georgia, Athens, United States
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19
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Molecular characterization and transcriptional regulation of two types of H +-pyrophosphatases in the scuticociliate parasite Philasterides dicentrarchi. Sci Rep 2021; 11:8519. [PMID: 33875762 PMCID: PMC8055999 DOI: 10.1038/s41598-021-88102-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/08/2021] [Indexed: 02/02/2023] Open
Abstract
Proton-translocating inorganic pyrophosphatases (H+-PPases) are an ancient family of membrane bound enzymes that couple pyrophosphate (PPi) hydrolysis to H+ translocation across membranes. In this study, we conducted a molecular characterization of two isoenzymes (PdVP1 and PdVP2) located in respectively the alveolar sacs and in the membranes of the intracellular vacuoles of a scuticociliate parasite (Philasterides dicentrarchi) of farmed turbot. We analyzed the genetic expression of the isoenzymes after administration of antiparasitic drugs and after infection in the host. PdVP1 and PdVP2 are encoded by two genes of 2485 and 3069 bp, which respectively contain 3 and 11 exons and express proteins of 746 and 810 aa of molecular mass 78.9 and 87.6 kDa. Topological predictions from isoenzyme sequences indicate the formation of thirteen transmembrane regions (TMRs) for PdVP1 and seventeen TMRs for PdVP2. Protein structure modelling indicated that both isoenzymes are homodimeric, with three Mg2+ binding sites and an additional K+ binding site in PdVP2. The levels of identity and similarity between the isoenzyme sequences are respectively 33.5 and 51.2%. The molecular weights of the native proteins are 158 kDa (PdVP1) and 178 kDa (PdVP2). The isoenzyme sequences are derived from paralogous genes that form a monophyletic grouping with other ciliate species. Genetic expression of the isoenzymes is closely related to the acidification of alveolar sacs (PdVP1) and intracellular vacuoles (PdVP2): antiparasitic drugs inhibit transcription, while infection increases transcription of both isoenzymes. The study findings show that P. dicentrarchi possesses two isoenzymes with H+-PPase activity which are located in acidophilic cell compartment membranes and which are activated during infection in the host and are sensitive to antiparasitic drugs. The findings open the way to using molecular modelling to design drugs for the treatment of scuticociliatosis.
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20
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Stasic AJ, Dykes EJ, Cordeiro CD, Vella SA, Fazli MS, Quinn S, Docampo R, Moreno SNJ. Ca 2+ entry at the plasma membrane and uptake by acidic stores is regulated by the activity of the V-H + -ATPase in Toxoplasma gondii. Mol Microbiol 2021; 115:1054-1068. [PMID: 33793004 DOI: 10.1111/mmi.14722] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/21/2021] [Accepted: 03/26/2021] [Indexed: 12/14/2022]
Abstract
Ca2+ is a universal intracellular signal that regulates many cellular functions. In Toxoplasma gondii, the controlled influx of extracellular and intracellular Ca2+ into the cytosol initiates a signaling cascade that promotes pathogenic processes like tissue destruction and dissemination. In this work, we studied the role of proton transport in cytosolic Ca2+ homeostasis and the initiation of Ca2+ signaling. We used a T. gondii mutant of the V-H+ -ATPase, a pump previously shown to transport protons to the extracellular medium, and to control intracellular pH and membrane potential and we show that proton gradients are important for maintaining resting cytosolic Ca2+ at physiological levels and for Ca2+ influx. Proton transport was also important for Ca2+ storage by acidic stores and, unexpectedly, the endoplasmic reticulum. Proton transport impacted the amount of polyphosphate (polyP), a phosphate polymer that binds Ca2+ and concentrates in acidocalcisomes. This was supported by the co-localization of the vacuolar transporter chaperone 4 (VTC4), the catalytic subunit of the VTC complex that synthesizes polyP, with the V-ATPase in acidocalcisomes. Our work shows that proton transport regulates plasma membrane Ca2+ transport and control acidocalcisome polyP and Ca2+ content, impacting Ca2+ signaling and downstream stimulation of motility and egress in T. gondii.
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Affiliation(s)
- Andrew J Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA
| | - Eric J Dykes
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Ciro D Cordeiro
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA
| | - Mojtaba S Fazli
- Department of Computer Sciences, University of Georgia, Athens, GA, USA
| | - Shannon Quinn
- Department of Cellular Biology, University of Georgia, Athens, GA, USA.,Department of Computer Sciences, University of Georgia, Athens, GA, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Georgia, GA, USA.,Department of Cellular Biology, University of Georgia, Athens, GA, USA
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21
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Tagoe DNA, Drozda AA, Falco JA, Bechtel TJ, Weerapana E, Gubbels MJ. Ferlins and TgDOC2 in Toxoplasma Microneme, Rhoptry and Dense Granule Secretion. Life (Basel) 2021; 11:217. [PMID: 33803212 PMCID: PMC7999867 DOI: 10.3390/life11030217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/02/2021] [Accepted: 03/05/2021] [Indexed: 12/25/2022] Open
Abstract
The host cell invasion process of apicomplexan parasites like Toxoplasma gondii is facilitated by sequential exocytosis of the microneme, rhoptry and dense granule organelles. Exocytosis is facilitated by a double C2 domain (DOC2) protein family. This class of C2 domains is derived from an ancestral calcium (Ca2+) binding archetype, although this feature is optional in extant C2 domains. DOC2 domains provide combinatorial power to the C2 domain, which is further enhanced in ferlins that harbor 5-7 C2 domains. Ca2+ conditionally engages the C2 domain with lipids, membranes, and/or proteins to facilitating vesicular trafficking and membrane fusion. The widely conserved T. gondii ferlins 1 (FER1) and 2 (FER2) are responsible for microneme and rhoptry exocytosis, respectively, whereas an unconventional TgDOC2 is essential for microneme exocytosis. The general role of ferlins in endolysosmal pathways is consistent with the repurposed apicomplexan endosomal pathways in lineage specific secretory organelles. Ferlins can facilitate membrane fusion without SNAREs, again pertinent to the Apicomplexa. How temporal raises in Ca2+ combined with spatiotemporally available membrane lipids and post-translational modifications mesh to facilitate sequential exocytosis events is discussed. In addition, new data on cross-talk between secretion events together with the identification of a new microneme protein, MIC21, is presented.
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Affiliation(s)
- Daniel N. A. Tagoe
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
| | - Allison A. Drozda
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
| | - Julia A. Falco
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Tyler J. Bechtel
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Eranthie Weerapana
- Department of Chemistry, Boston College, Chestnut Hill, MA 02467, USA; (J.A.F.); (T.J.B.); (E.W.)
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; (D.N.A.T.); (A.A.D.)
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22
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Wang X, Tang D, Wang F, Jin G, Wang L, Liu Q, Liu J. Microneme Protein 6 Is Involved in Invasion and Egress by Neospora caninum. Pathogens 2021; 10:pathogens10020201. [PMID: 33668497 PMCID: PMC7918358 DOI: 10.3390/pathogens10020201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 02/04/2021] [Accepted: 02/10/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Neospora caninum, is the etiological agent of neosporosis, an infection that causes abortions in cattle and nervous system dysfunction in dogs. Invasion and egress are the key steps of the pathogenesis of N. caninum infection. Microneme proteins (MICs) play important roles in the recognition, adhesion, and invasion of host cells in other apicomplexan parasites. However, some MICs and their functions in N. caninum infection have rarely been reported. METHODS The homologous recombination strategy was used to investigate the function of MIC6 in N. caninum infection. RESULTS ΔNcMIC6 showed a smaller plaque size and weakened capacities of invasion and egress than Nc1. Transcription levels of the egress-related genes CDPK1, PLP1, and AMA1 of ΔNcMIC6 were downregulated. Due to the lack of NcMIC6, virulence of the pathogen in the infected mouse was weakened. The subcellular localization of NcMIC1 and NcMIC4 in ΔNcMIC6, however, did not change. Nevertheless, the transcription levels of MIC1 and MIC4 in ΔNcMIC6 were downregulated, and the expression and secretion of MIC1 and MIC4 in ΔNcMIC6 were reduced compared with that in Nc1. Furthermore, the absence of NcMIC6 weakened the virulence in mice and lower parasite load detected in mice brains. CONCLUSIONS NcMIC6 is involved in host cell invasion and egress in N. caninum and may work synergistically with other MICs to regulate the virulence of the pathogen. These data lay a foundation for further research into the function and application of NcMIC6.
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23
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Hu CX, Zeng J, Hao HN, Xu YXY, Liu F, Liu RD, Long SR, Wang ZQ, Cui J. Biological properties and roles of a Trichinella spiralis inorganic pyrophosphatase in molting and developmental process of intestinal larval stages. Vet Res 2021; 52:6. [PMID: 33413587 PMCID: PMC7791673 DOI: 10.1186/s13567-020-00877-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/03/2020] [Indexed: 12/26/2022] Open
Abstract
Inorganic pyrophosphatase (PPase) participates in energy cycle and plays a vital role in hydrolysis of inorganic pyrophosphate (PPi) into inorganic phosphate (Pi). The aim of this study was to investigate the biological properties of a Trichinella spiralis PPase (TsPPase) and its role in larval molting and developmental process. The predicted TsPPase consisted of 367 amino acids with a molecular mass of 41.48 kDa and a pI of 5.76. Amino acid sequence alignment and phylogenetic analysis showed that the TsPPase gene encodes a functional family I soluble PPase with the same characteristics as prokaryotic, plant and animal/fungal soluble PPase. The rTsPPase was expressed and purified, it has the activity to catalyze the hydrolysis of PPi to Pi, and the activity was dependent on Mg2+, pH and temperature. The enzymatic activity of rTsPPase was significantly inhibited after its metal binding sites mutation. TsPPase was transcribed and expressed in all T. spiralis phases, especially in muscle larvae (ML) and intestinal infective larvae (IIL). Immunofluorescence assay (IFA) revealed that TsPPase was mainly located in cuticle and stichosome. When the ML and IIL were treated with TsPPase-specific siRNA-279, TsPPase expression and enzymatic activity were obviously reduced, the larval molting and development were also impeded. Intestinal IIL as well as AW burden, IIL molting rates from mice infected with siRNA-treated ML were obviously suppressed. The results indicated that rTsPPase possesses the enzymatic activity of native inorganic pyrophosphatase, and TsPPase plays an important role in development and molting process of intestinal T. spiralis larval stages.
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Affiliation(s)
- Chen Xi Hu
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Jie Zeng
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Hui Nan Hao
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Yang Xiu Yue Xu
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Fang Liu
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Ruo Dan Liu
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Shao Rong Long
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China
| | - Zhong Quan Wang
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China.
| | - Jing Cui
- Department of Parasitology, Medical College, Zhengzhou University, Zhengzhou, 450052, China.
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24
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Bisio H, Soldati-Favre D. Signaling Cascades Governing Entry into and Exit from Host Cells by Toxoplasma gondii. Annu Rev Microbiol 2020; 73:579-599. [PMID: 31500539 DOI: 10.1146/annurev-micro-020518-120235] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Apicomplexa phylum includes a large group of obligate intracellular protozoan parasites responsible for important diseases in humans and animals. Toxoplasma gondii is a widespread parasite with considerable versatility, and it is capable of infecting virtually any warm-blooded animal, including humans. This outstanding success can be attributed at least in part to an efficient and continuous sensing of the environment, with a ready-to-adapt strategy. This review updates the current understanding of the signals governing the lytic cycle of T. gondii, with particular focus on egress from infected cells, a key step for balancing survival, multiplication, and spreading in the host. We cover the recent advances in the conceptual framework of regulation of microneme exocytosis that ensures egress, motility, and invasion. Particular emphasis is given to the trigger molecules and signaling cascades regulating exit from host cells.
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Affiliation(s)
- Hugo Bisio
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Université de Genève, 1211 Geneva 4, Switzerland;
| | - Dominique Soldati-Favre
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, Université de Genève, 1211 Geneva 4, Switzerland;
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25
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Stasic AJ, Chasen NM, Dykes EJ, Vella SA, Asady B, Starai VJ, Moreno SNJ. The Toxoplasma Vacuolar H +-ATPase Regulates Intracellular pH and Impacts the Maturation of Essential Secretory Proteins. Cell Rep 2020; 27:2132-2146.e7. [PMID: 31091451 PMCID: PMC6760873 DOI: 10.1016/j.celrep.2019.04.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 10/31/2018] [Accepted: 04/05/2019] [Indexed: 12/20/2022] Open
Abstract
Vacuolar-proton ATPases (V-ATPases) are conserved complexes that couple the hydrolysis of ATP to the pumping of protons across membranes. V-ATPases are known to play diverse roles in cellular physiology. We studied the Toxoplasma gondii V-ATPase complex and discovered a dual role of the pump in protecting parasites against ionic stress and in the maturation of secretory proteins in endosomal-like compartments. Toxoplasma V-ATPase subunits localize to the plasma membrane and to acidic vesicles, and characterization of conditional mutants of the a1 subunit highlighted the functionality of the complex at both locations. Microneme and rhoptry proteins are required for invasion and modulation of host cells, and they traffic via endosome-like compartments in which proteolytic maturation occurs. We show that the V-ATPase supports the maturation of rhoptry and microneme proteins, and their maturases, during their traffic to their corresponding organelles. This work underscores a role for V-ATPases in regulating virulence pathways. Stasic et al. characterize the function of the vacuolar proton ATPase in the life cycle of Toxoplasma gondii, a widespread parasite that infects almost one-third of the world’s population. The work presents molecular evidence of the pump’s role in the synthesis of virulence factors of a highly successful pathogen.
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Affiliation(s)
- Andrew J Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA; Department of Microbiology, University of Georgia, Athens, GA 30602-7400, USA
| | - Nathan M Chasen
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA; Department of Infectious Diseases, University of Georgia, Athens, GA 30602-7400, USA
| | - Eric J Dykes
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA
| | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA; Department of Microbiology, University of Georgia, Athens, GA 30602-7400, USA
| | - Beejan Asady
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA
| | - Vincent J Starai
- Department of Microbiology, University of Georgia, Athens, GA 30602-7400, USA; Department of Infectious Diseases, University of Georgia, Athens, GA 30602-7400, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602-7400, USA; Department of Cellular Biology, University of Georgia, Athens, GA 30602-7400, USA.
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26
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Johansson NG, Turku A, Vidilaseris K, Dreano L, Khattab A, Ayuso Pérez D, Wilkinson A, Zhang Y, Tamminen M, Grazhdankin E, Kiriazis A, Fishwick CWG, Meri S, Yli-Kauhaluoma J, Goldman A, Boije af Gennäs G, Xhaard H. Discovery of Membrane-Bound Pyrophosphatase Inhibitors Derived from an Isoxazole Fragment. ACS Med Chem Lett 2020; 11:605-610. [PMID: 32292570 PMCID: PMC7153278 DOI: 10.1021/acsmedchemlett.9b00537] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/10/2020] [Indexed: 12/21/2022] Open
Abstract
![]()
Membrane-bound
pyrophosphatases (mPPases) regulate energy homeostasis
in pathogenic protozoan parasites and lack human homologues, which
makes them promising targets in e.g. malaria. Yet
only few nonphosphorus inhibitors have been reported so far. Here,
we explore an isoxazole fragment hit, leading to the discovery of
small mPPase inhibitors with 6–10 μM IC50 values
in the Thermotoga maritima test system. Promisingly,
the compounds retained activity against Plasmodium falciparum mPPase in membranes and inhibited parasite growth.
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Affiliation(s)
- Niklas G. Johansson
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Ainoleena Turku
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Keni Vidilaseris
- Department of Biosciences, Division of Biochemistry, University of Helsinki, P.O. Box 56
(Viikinkaari 9), FI-00014 Helsinki, Finland
| | - Loïc Dreano
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Ayman Khattab
- Malaria Research Laboratory, Translational Immunology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, P.O. Box 21
(Haartmaninkatu 3), FI-00014 Helsinki, Finland
| | - Daniel Ayuso Pérez
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Aaron Wilkinson
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Yuezhou Zhang
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Matti Tamminen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Evgeni Grazhdankin
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Alexandros Kiriazis
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Colin W. G. Fishwick
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Seppo Meri
- Malaria Research Laboratory, Translational Immunology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, P.O. Box 21
(Haartmaninkatu 3), FI-00014 Helsinki, Finland
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Adrian Goldman
- Department of Biosciences, Division of Biochemistry, University of Helsinki, P.O. Box 56
(Viikinkaari 9), FI-00014 Helsinki, Finland
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Clarendon Way, Leeds LS2 9JT, United Kingdom
| | - Gustav Boije af Gennäs
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56 (Viikinkaari 5 E), FI-00014 Helsinki, Finland
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27
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Gouiaa S, Khoudi H. Expression of V-PPase proton pump, singly or in combination with a NHX1 transporter, in transgenic tobacco improves copper tolerance and accumulation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:37037-37045. [PMID: 31745765 DOI: 10.1007/s11356-019-06852-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/22/2019] [Indexed: 05/27/2023]
Abstract
One of the most important strategies evolved by plants to tolerate heavy metals (HMs) is their sequestration into the vacuole. Recent studies have demonstrated that Cu sequestration into vacuole is dependent on the electrochemical gradient generated by vacuolar proton pumps: the V-H+-PPase and the V-H+-ATPase. In a previous study, we demonstrated that co-expression of V-H+-PPase and a sodium/proton antiporter genes, isolated from wheat, in transgenic tobacco plants significantly increases both H+ pumping activity of the endogenous V-H+-ATPase and V-H+-PPase compared to wild-type (WT) plants, all grown in the absence of stress. In the present study, we evaluated the effect of expression, in tobacco, of vacuolar proton pump, TaVP1, singly or in combination with sodium/proton antiporter, TaNHXS1, on copper (Cu) tolerance and accumulation. Results showed that, when subjected to Cu stress, TaVP1 single transgenic tobacco lines exhibited a more robust root system, greater biomass production, less chlorophyll loss, lower MDA and H2O2 production, and higher catalase activity and accumulated more Cu than did WT. Interestingly, double transgenic tobacco lines exhibited the best Cu tolerance and accumulation than either of the single TaVP1 transgenic lines or WT plants, when subjected to excess Cu. In fact, double transgenic lines accumulated 2.5-fold and 1.9-fold more Cu than did WT and single TaVP1 lines, respectively. Thus, these results clearly demonstrate the usefulness of expression of vacuolar proton pump alone or in combination with sodium/proton antiporter as novel strategy for Cu phytoremediation.
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Affiliation(s)
- Sandra Gouiaa
- Laboratory of Plant Biotechnology and Improvement, University of Sfax, Center of Biotechnology of Sfax, Route Sidi Mansour, Km 6 B.P' 1177, 3018, Sfax, Tunisia
| | - Habib Khoudi
- Laboratory of Plant Biotechnology and Improvement, University of Sfax, Center of Biotechnology of Sfax, Route Sidi Mansour, Km 6 B.P' 1177, 3018, Sfax, Tunisia.
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28
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Holmes AOM, Kalli AC, Goldman A. The Function of Membrane Integral Pyrophosphatases From Whole Organism to Single Molecule. Front Mol Biosci 2019; 6:132. [PMID: 31824962 PMCID: PMC6882861 DOI: 10.3389/fmolb.2019.00132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/08/2019] [Indexed: 12/02/2022] Open
Abstract
Membrane integral pyrophosphatases (mPPases) are responsible for the hydrolysis of pyrophosphate. This enzymatic mechanism is coupled to the pumping of H+ or Na+ across membranes in a process that can be K+ dependent or independent. Understanding the movements and dynamics throughout the mPPase catalytic cycle is important, as this knowledge is essential for improving or impeding protein function. mPPases have been shown to play a crucial role in plant maturation and abiotic stress tolerance, and so have the potential to be engineered to improve plant survival, with implications for global food security. mPPases are also selectively toxic drug targets, which could be pharmacologically modulated to reduce the virulence of common human pathogens. The last few years have seen the publication of many new insights into the function and structure of mPPases. In particular, there is a new body of evidence that the catalytic cycle is more complex than originally proposed. There are structural and functional data supporting a mechanism involving half-of-the-sites reactivity, inter-subunit communication, and exit channel motions. A more advanced and in-depth understanding of mPPases has begun to be uncovered, leaving the field of research with multiple interesting avenues for further exploration and investigation.
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Affiliation(s)
- Alexandra O. M. Holmes
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Antreas C. Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
| | - Adrian Goldman
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
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Thornton LB, Teehan P, Floyd K, Cochrane C, Bergmann A, Riegel B, Stasic AJ, Di Cristina M, Moreno SNJ, Roepe PD, Dou Z. An ortholog of Plasmodium falciparum chloroquine resistance transporter (PfCRT) plays a key role in maintaining the integrity of the endolysosomal system in Toxoplasma gondii to facilitate host invasion. PLoS Pathog 2019; 15:e1007775. [PMID: 31170269 PMCID: PMC6553793 DOI: 10.1371/journal.ppat.1007775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/22/2019] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma gondii is an apicomplexan parasite with the ability to use foodborne, zoonotic, and congenital routes of transmission that causes severe disease in immunocompromised patients. The parasites harbor a lysosome-like organelle, termed the "Vacuolar Compartment/Plant-Like Vacuole" (VAC/PLV), which plays an important role in maintaining the lytic cycle and virulence of T. gondii. The VAC supplies proteolytic enzymes that contribute to the maturation of invasion effectors and that digest autophagosomes and endocytosed host proteins. Previous work identified a T. gondii ortholog of the Plasmodium falciparum chloroquine resistance transporter (PfCRT) that localized to the VAC. Here, we show that TgCRT is a membrane transporter that is functionally similar to PfCRT. We also genetically ablate TgCRT and reveal that the TgCRT protein plays a key role in maintaining the integrity of the parasite’s endolysosomal system by controlling morphology of the VAC. When TgCRT is absent, the VAC dramatically increases in volume by ~15-fold and overlaps with adjacent endosome-like compartments. Presumably to reduce aberrant swelling, transcription and translation of endolysosomal proteases are decreased in ΔTgCRT parasites. Expression of subtilisin protease 1 is significantly reduced, which impedes trimming of microneme proteins, and significantly decreases parasite invasion. Chemical or genetic inhibition of proteolysis within the VAC reverses these effects, reducing VAC size and partially restoring integrity of the endolysosomal system, microneme protein trimming, and invasion. Taken together, these findings reveal for the first time a physiological role of TgCRT in substrate transport that impacts VAC volume and the integrity of the endolysosomal system in T. gondii. Toxoplasma gondii is an obligate intracellular protozoan parasite that belongs to the phylum Apicomplexa and that infects virtually all warm-blooded organisms. Approximately one-third of the human population is infected with Toxoplasma. Toxoplasma invades host cells using processed invasion effectors. A lysosome-like organelle (VAC) is involved in refining these invasion effectors to reach their final forms. A T. gondii ortholog of the malarial chloroquine resistance transporter protein (TgCRT) was found to be localized to the VAC membrane. Although the mutated version of the malarial chloroquine resistance transporter (PfCRT) has been shown to confer resistance to chloroquine treatment, its physiologic function remains poorly understood. Comparison between the related PfCRT and TgCRT facilitates definition of the physiologic role of CRT proteins. Here, we report that TgCRT plays a key role in affecting the integrity and proteolytic activity of the VAC and adjacent organelles, the secretion of invasion effectors, and parasite invasion and virulence. To relieve osmotic stress caused by VAC swelling when TgCRT is deleted, parasites repress proteolysis within this organelle to decrease solute accumulation, which then has secondary effects on parasite invasion. Our findings highlight a common function for PfCRT and TgCRT in mediating small solute transport to affect apicomplexan parasite vacuolar size and function.
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Affiliation(s)
- L. Brock Thornton
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Paige Teehan
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Katherine Floyd
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Christian Cochrane
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Amy Bergmann
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Bryce Riegel
- Department of Chemistry, Georgetown University, NW, Washington DC, United States of America
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, NW, Washington DC, United States of America
| | - Andrew J. Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Paul D. Roepe
- Department of Chemistry, Georgetown University, NW, Washington DC, United States of America
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, NW, Washington DC, United States of America
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- * E-mail:
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Chasen NM, Stasic AJ, Asady B, Coppens I, Moreno SNJ. The Vacuolar Zinc Transporter TgZnT Protects Toxoplasma gondii from Zinc Toxicity. mSphere 2019; 4:e00086-19. [PMID: 31118298 PMCID: PMC6531880 DOI: 10.1128/msphere.00086-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/30/2019] [Indexed: 02/08/2023] Open
Abstract
Zinc (Zn2+) is the most abundant biological metal ion aside from iron and is an essential element in numerous biological systems, acting as a cofactor for a large number of enzymes and regulatory proteins. Zn2+ must be tightly regulated, as both the deficiency and overabundance of intracellular free Zn2+ are harmful to cells. Zn2+ transporters (ZnTs) play important functions in cells by reducing intracellular Zn2+ levels by transporting the ion out of the cytoplasm. We characterized a Toxoplasma gondii gene (TgGT1_251630, TgZnT), which is annotated as the only ZnT family Zn2+ transporter in T. gondii TgZnT localizes to novel vesicles that fuse with the plant-like vacuole (PLV), an endosome-like organelle. Mutant parasites lacking TgZnT exhibit reduced viability in in vitro assays. This phenotype was exacerbated by increasing zinc concentrations in the extracellular media and was rescued by media with reduced zinc. Heterologous expression of TgZnT in a Zn2+-sensitive Saccharomyces cerevisiae yeast strain partially restored growth in media with higher Zn2+ concentrations. These results suggest that TgZnT transports Zn2+ into the PLV and plays an important role in the Zn2+ tolerance of T. gondii extracellular tachyzoites.IMPORTANCEToxoplasma gondii is an intracellular pathogen of human and animals. T. gondii pathogenesis is associated with its lytic cycle, which involves invasion, replication, egress out of the host cell, and invasion of a new one. T. gondii must be able to tolerate abrupt changes in the composition of the surrounding milieu as it progresses through its lytic cycle. We report the characterization of a Zn2+ transporter of T. gondii (TgZnT) that is important for parasite growth. TgZnT restored Zn2+ tolerance in yeast mutants that were unable to grow in media with high concentrations of Zn2+ We propose that TgZnT plays a role in Zn2+ homeostasis during the T. gondii lytic cycle.
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Affiliation(s)
- Nathan M Chasen
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - Andrew J Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Beejan Asady
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
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Vidilaseris K, Kiriazis A, Turku A, Khattab A, Johansson NG, Leino TO, Kiuru PS, Boije af Gennäs G, Meri S, Yli-Kauhaluoma J, Xhaard H, Goldman A. Asymmetry in catalysis by Thermotoga maritima membrane-bound pyrophosphatase demonstrated by a nonphosphorus allosteric inhibitor. SCIENCE ADVANCES 2019; 5:eaav7574. [PMID: 31131322 PMCID: PMC6530997 DOI: 10.1126/sciadv.aav7574] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 04/16/2019] [Indexed: 06/09/2023]
Abstract
Membrane-bound pyrophosphatases are homodimeric integral membrane proteins that hydrolyze pyrophosphate into orthophosphates, coupled to the active transport of protons or sodium ions across membranes. They are important in the life cycle of bacteria, archaea, plants, and parasitic protists, but no homologous proteins exist in vertebrates, making them a promising drug target. Here, we report the first nonphosphorus allosteric inhibitor of the thermophilic bacterium Thermotoga maritima membrane-bound pyrophosphatase and its bound structure together with the substrate analog imidodiphosphate. The unit cell contains two protein homodimers, each binding a single inhibitor dimer near the exit channel, creating a hydrophobic clamp that inhibits the movement of β-strand 1-2 during pumping, and thus prevents the hydrophobic gate from opening. This asymmetry of inhibitor binding with respect to each homodimer provides the first clear structural demonstration of asymmetry in the catalytic cycle of membrane-bound pyrophosphatases.
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Affiliation(s)
- Keni Vidilaseris
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
| | - Alexandros Kiriazis
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Ainoleena Turku
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Ayman Khattab
- Malaria Research Laboratory, Immunobiology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Niklas G. Johansson
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Teppo O. Leino
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Paula S. Kiuru
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Gustav Boije af Gennäs
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Seppo Meri
- Malaria Research Laboratory, Immunobiology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Adrian Goldman
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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Chang L, Zhang X, Gong P, Wang Y, Du B, Li J. Identification and characterization of Letm1 gene in Toxoplasma gondii. Acta Biochim Biophys Sin (Shanghai) 2019; 51:78-87. [PMID: 30423025 DOI: 10.1093/abbs/gmy138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/11/2018] [Indexed: 01/22/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis. Previous studies have shown that the perturbation of mitochondrial metabolism in T. gondii results in growth deficiency in host cells and lack of virulence in animals. Members of this Letm1 protein family are inner mitochondrial membrane proteins which play a role in potassium and hydrogen ion exchange. Letm1 has not been characterized in T. gondii. In this study, a potential TgLetm1 gene (TgGT1_288400) with Letm1-like protein domain coding sequence was identified in T. gondii. Indirect immunofluorescence assays suggested that TgLetm1 localized to the mitochondria in tachyzoites, as indicated by the colocalization with mitochondrial marker Mitotracker. TgLetm1 was found in the membrane fraction by western blot analysis. To investigate the role of TgLetm1 in T. gondii, we generated a tetracycline-inducible TgLetm1-knock-down mutant. The conditional deletion of TgLetm1 resulted in mitochondrial swelling. Functional studies showed that the conditional deletion of TgLetm1 resulted in growth inhibition, deficiency in invasion and replication, and lack of virulence in mice.
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Affiliation(s)
- Le Chang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xichen Zhang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Pengtao Gong
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yuru Wang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Boya Du
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianhua Li
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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Chang L, Dykes EJ, Li J, Moreno SNJ, Hortua Triana MA. Characterization of Two EF-hand Domain-containing Proteins from Toxoplasma gondii. J Eukaryot Microbiol 2018; 66:343-353. [PMID: 30063275 DOI: 10.1111/jeu.12675] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 07/25/2018] [Accepted: 07/26/2018] [Indexed: 12/01/2022]
Abstract
The universal role of calcium (Ca2+ ) as a second messenger in cells depends on a large number of Ca2+ -binding proteins (CBP), which are able to bind Ca2+ through specific domains. Many CBPs share a type of Ca2+ -binding domain known as the EF-hand. The EF-hand motif has been well studied and consists of a helix-loop-helix structural domain with specific amino acids in the loop region that interact with Ca2+ . In Toxoplasma gondii a large number of genes (approximately 68) are predicted to have at least one EF-hand motif. The majority of these genes have not been characterized. We report the characterization of two EF-hand motif-containing proteins, TgGT1_216620 and TgGT1_280480, which localize to the plasma membrane and to the rhoptry bulb, respectively. Genetic disruption of these genes by CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) resulted in mutant parasite clones (Δtg216620 and Δtg280480) that grew at a slower rate than control cells. Ca2+ measurements showed that Δtg216620 cells did not respond to extracellular Ca2+ as the parental controls while Δtg280480 cells appeared to respond as the parental cells. Our hypothesis is that TgGT1_216620 is important for Ca2+ influx while TgGT1_280480 may be playing a different role in the rhoptries.
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Affiliation(s)
- Le Chang
- College of Veterinary Medicine, Jilin University, Changchun, 130062, China.,Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Eric J Dykes
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Jianhua Li
- College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602.,Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602
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Strauss J, Wilkinson C, Vidilaseris K, Harborne SPD, Goldman A. A Simple Strategy to Determine the Dependence of Membrane-Bound Pyrophosphatases on K + as a Cofactor. Methods Enzymol 2018; 607:131-156. [PMID: 30149856 DOI: 10.1016/bs.mie.2018.04.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Membrane-bound pyrophosphatases (mPPases) couple pyrophosphate hydrolysis to H+ and/or Na+ pumping across membranes and are found in all domains of life except for multicellular animals including humans. They are important for development and stress resistance in plants. Furthermore, mPPases play a role in virulence of human pathogens that cause severe diseases such as malaria and African sleeping sickness. Sequence analysis, functional studies, and recently solved crystal structures have contributed to the understanding of the mPPase catalytic cycle. However, several key mechanistic features remain unknown. During evolution, several subgroups of mPPases differing in their pumping specificity and cofactor dependency arose. mPPases are classified into one of five subgroups, usually by sequence analysis. However, classification based solely on sequence has been inaccurate in several instances due to our limited understanding of the molecular mechanism of mPPases. Thus, pumping specificity and cofactor dependency of mPPases require experimental confirmation. Here, we describe a simple method for the determination of K+ dependency in mPPases using a hydrolytic activity assay. By coupling these dependency studies with site-directed mutagenesis, we have begun to build a better understanding of the molecular mechanisms of mPPases. We optimized the assay for thermostable mPPases that are commonly used as model systems in our lab, but the method is equally applicable to mesophilic mPPases with minor modifications.
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Affiliation(s)
- Jannik Strauss
- Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
| | - Craig Wilkinson
- Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
| | - Keni Vidilaseris
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Steven P D Harborne
- Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom.
| | - Adrian Goldman
- Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom; Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
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Hortua Triana MA, Márquez-Nogueras KM, Chang L, Stasic AJ, Li C, Spiegel KA, Sharma A, Li ZH, Moreno SNJ. Tagging of Weakly Expressed Toxoplasma gondii Calcium-Related Genes with High-Affinity Tags. J Eukaryot Microbiol 2018; 65:709-721. [PMID: 29672999 DOI: 10.1111/jeu.12626] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/21/2022]
Abstract
Calcium ions regulate a diversity of cellular functions in all eukaryotes. The cytosolic Ca2+ concentration is tightly regulated at the physiological cytosolic concentration of 50-100 nm. The Toxoplasma gondii genome predicts the presence of several genes encoding potential Ca2+ channels, pumps, and transporters. Many of these genes are weakly expressed and likely tightly regulated due to their potential impact to the physiology of the cell. Endogenous tagging has been widely used to localize proteins in T. gondii but low level of expression of many of them makes visualization of tags difficult and sometimes impossible. The use of high-performance tags for labeling proteins expressed at low level is ideal for investigating the localization of these gene products. We designed a Carboxy-terminus tagging plasmid containing the previously characterized "spaghetti monster-HA" (smHA) or "spaghetti monster-MYC" (smMYC) tags. These tags consist of 10 copies of a single epitope (HA or MYC) inserted into a darkened green fluorescence protein scaffold. We localized six proteins of various levels of expression. Clonal lines were isolated and validated by PCR, western blot, and immunofluorescence analyses. Some gene products were only visible when tagged with smHA and in one case the smHA revealed a novel localization previously undetected.
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Affiliation(s)
- Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | | | - Le Chang
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Andrew J Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Catherine Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Kevin A Spiegel
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Amrita Sharma
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602.,Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, 30602.,Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602
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Resistance towards monensin is proposed to be acquired in a Toxoplasma gondii model by reduced invasion and egress activities, in addition to increased intracellular replication. Parasitology 2017; 145:313-325. [PMID: 28870270 DOI: 10.1017/s0031182017001512] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Monensin (Mon) is an anticoccidial polyether ionophore widely used to control coccidiosis. The extensive use of polyether ionophores on poultry farms resulted in widespread resistance, but the underlying resistance mechanisms are unknown in detail. For analysing the mode of action by which resistance against polyether ionophores is obtained, we induced in vitro Mon resistance in Toxoplasma gondii-RH strain (MonR-RH) and compared it with the sensitive parental strain (Sen-RH). The proteome assessment of MonR-RH and Sen-RH strains was obtained after isotopic labelling using stable isotope labelling by amino acid in cell culture. Relative proteomic quantification between resistant and sensitive strains was performed using liquid chromatography-mass spectrometry/mass spectrometry. Overall, 1024 proteins were quantified and 52 proteins of them were regulated. The bioinformatic analysis revealed regulation of cytoskeletal and transmembrane proteins being involved in transport mechanisms, metal ion-binding and invasion. During invasion, actin and microneme protein 8 (MIC8) are seem to be important for conoid extrusion and forming moving junction with host cells, respectively. Actin was significantly upregulated, while MIC8 was downregulated, which indicate an invasion reduction in the resistant strain. Resistance against Mon is not a simple process but it involves reduced invasion and egress activity of T. gondii tachyzoites while intracellular replication is enhanced.
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Chasen NM, Asady B, Lemgruber L, Vommaro RC, Kissinger JC, Coppens I, Moreno SNJ. A Glycosylphosphatidylinositol-Anchored Carbonic Anhydrase-Related Protein of Toxoplasma gondii Is Important for Rhoptry Biogenesis and Virulence. mSphere 2017; 2:e00027-17. [PMID: 28529974 PMCID: PMC5437132 DOI: 10.1128/msphere.00027-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/19/2017] [Indexed: 01/06/2023] Open
Abstract
Carbonic anhydrase-related proteins (CARPs) have previously been described as catalytically inactive proteins closely related to α-carbonic anhydrases (α-CAs). These CARPs are found in animals (both vertebrates and invertebrates) and viruses as either independent proteins or domains of other proteins. We report here the identification of a new CARP (TgCA_RP) in the unicellular organism Toxoplasma gondii that is related to the recently described η-class CA found in Plasmodium falciparum. TgCA_RP is posttranslationally modified at its C terminus with a glycosylphosphatidylinositol anchor that is important for its localization in intracellular tachyzoites. The protein localizes throughout the rhoptry bulbs of mature tachyzoites and to the outer membrane of nascent rhoptries in dividing tachyzoites, as demonstrated by immunofluorescence and immunoelectron microscopy using specific antibodies. T. gondii mutant tachyzoites lacking TgCA_RP display a growth and invasion phenotype in vitro and have atypical rhoptry morphology. The mutants also exhibit reduced virulence in a mouse model. Our results show that TgCA_RP plays an important role in the biogenesis of rhoptries. IMPORTANCEToxoplasma gondii is an intracellular pathogen that infects humans and animals. The pathogenesis of T. gondii is linked to its lytic cycle, which starts when tachyzoites invade host cells and secrete proteins from specialized organelles. Once inside the host cell, the parasite creates a parasitophorous vacuole (PV) where it divides. Rhoptries are specialized secretory organelles that contain proteins, many of which are secreted during invasion. These proteins have important roles not only during the initial interaction between parasite and host but also in the formation of the PV and in the modification of the host cell. We report here the identification of a new T. gondii carbonic anhydrase-related protein (TgCA_RP), which localizes to rhoptries of mature tachyzoites. TgCA_RP is important for the morphology of rhoptries and for invasion and growth of parasites. TgCA_RP is also critical for parasite virulence. We propose that TgCA_RP plays a role in the biogenesis of rhoptries.
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Affiliation(s)
- Nathan M. Chasen
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - Beejan Asady
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Leandro Lemgruber
- Instituto Nacional de Metrologia, Inmetro-RJ, UFRJ, Rio de Janeiro, Brazil
| | | | - Jessica C. Kissinger
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Genetics, University of Georgia, Athens, Georgia, USA
- Institute of Bioinformatics, University of Georgia, Athens, Georgia, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
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Tong C, Xiao B, Cheng S, Li W, Liao X, Luo S, Hao W. Generation and Identification of Peptide-Based Monoclonal Antibodies Against Vacuolar Proton Pyrophosphatase of Toxoplasma gondii. Monoclon Antib Immunodiagn Immunother 2016; 34:191-200. [PMID: 26090597 DOI: 10.1089/mab.2014.0093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vacuolar proton pyrophosphatase (V-PPase), an electrogenic proton pump widely distributed in non-mammalian species, is one of the important targets for acidocalcisomes. In this study, a novel method of peptide-based antibody generation was performed to produce monoclonal antibodies (MAbs) against Toxoplasma gondii V-PPase. Three hybridomas were identified and confirmed by ELISA, Western blotting, and immunofluorescence. All of them can react with an 85 kDa band of T. gondii protein in purified acidocalcisomal fraction. The three MAbs were all specific to the synthetic peptide of YTKAADVGADLSGKNEYGMSEDDPRNPAC, corresponding to amino acids at the location of 292aa-320aa of TgVP1 amino acid sequence. These specific MAbs will be valuable tools for further study of T. gondii infection biology, pathogenesis, and host immune response.
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Affiliation(s)
- Chengbi Tong
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Bin Xiao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Shasha Cheng
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Wei Li
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Xiaoqing Liao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Shuhong Luo
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
| | - Wenbo Hao
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of Biotechnology, Southern Medical University , Guangzhou, Guangdong, P.R. China
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Docampo R, Huang G. Acidocalcisomes of eukaryotes. Curr Opin Cell Biol 2016; 41:66-72. [PMID: 27125677 DOI: 10.1016/j.ceb.2016.04.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/30/2016] [Accepted: 04/07/2016] [Indexed: 01/01/2023]
Abstract
Acidocalcisomes are organelles rich in polyphosphate and cations and acidified by proton pumps. Although they have also been described in prokaryotes they have been better characterized in unicellular and multicellular eukaryotes. Eukaryotic acidocalcisomes belong to the group of lysosome-related organelles. They have a variety of functions, from the storage of cations and phosphorus to calcium signaling, autophagy, osmoregulation, blood coagulation, and inflammation. Acidocalcisomes of several unicellular eukaryotes possess a variety of transporters, channels and pumps implying a large energetic requirement for their maintenance and suggesting other important functions waiting to be discovered.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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R. Shah N, Vidilaseris K, Xhaard H, Goldman A. Integral membrane pyrophosphatases: a novel drug target for human pathogens? AIMS BIOPHYSICS 2016. [DOI: 10.3934/biophy.2016.1.171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Docampo R. The origin and evolution of the acidocalcisome and its interactions with other organelles. Mol Biochem Parasitol 2015; 209:3-9. [PMID: 26523947 DOI: 10.1016/j.molbiopara.2015.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/04/2015] [Accepted: 10/19/2015] [Indexed: 01/11/2023]
Abstract
Acidocalcisomes are acidic calcium stores that have been found from bacteria to human cells. They are rich in phosphorus compounds in the form of orthophosphate (Pi), pyrophosphate (PPi), and polyphosphate (polyP) and their acidity is maintained by proton pumps such as the vacuolar proton pyrophosphatase (V-H+-PPase, or VP1), the vacuolar proton ATPase (V-H+-ATPase), or both. Recent studies in trypanosomatids and in other species have revealed their role in phosphate metabolism, and cation and water homeostasis, as suggested by the presence of novel pumps, transporters, and channels. An important role in autophagy has also been described. The study of the biogenesis of acidocalcisomes as well as of the interactions of these lysosome-related organelles with other organelles have uncovered important roles in calcium signaling and osmoregulation. Significantly, despite conservation of acidocalcisomes across all of cellular life, there is evidence for intimate integration of these organelles with eukaryotic cellular functions, and which are directly relevant to parasites.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Global Emerging Diseases and Department of Cellular Biology, University of Georgia, Athens 30602, USA; Departamento de Patología Clínica, Universidade Estadual de Campinas, São Paulo 13083-877, Brazil.
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Lourido S, Moreno SNJ. The calcium signaling toolkit of the Apicomplexan parasites Toxoplasma gondii and Plasmodium spp. Cell Calcium 2014; 57:186-93. [PMID: 25605521 DOI: 10.1016/j.ceca.2014.12.010] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 12/21/2022]
Abstract
Apicomplexan parasites have complex life cycles, frequently split between different hosts and reliant on rapid responses as the parasites react to changing environmental conditions. Calcium ion (Ca(2+)) signaling is consequently essential for the cellular and developmental changes that support Apicomplexan parasitism. Apicomplexan genomes reveal a rich repertoire of genes involved in calcium signaling, although many of the genes responsible for observed physiological changes remain unknown. There is evidence, for example, for the presence of a nifedipine-sensitive calcium entry mechanism in Toxoplasma, but the molecular components involved in Ca(2+) entry in both Toxoplasma and Plasmodium, have not been identified. The major calcium stores are the endoplasmic reticulum (ER), the acidocalcisomes, and the plant-like vacuole in Toxoplasma, or the food vacuole in Plasmodium spp. Pharmacological evidence suggests that Ca(2+) release from intracellular stores may be mediated by inositol 1,4,5-trisphosphate (IP3) or cyclic ADP ribose (cADPR) although there is no molecular evidence for the presence of receptors for these second messengers in the parasites. Several Ca(2+)-ATPases are present in Apicomplexans and a putative mitochondrial Ca(2+)/H(+) exchanger has been identified. Apicomplexan genomes contain numerous genes encoding Ca(2+)-binding proteins, with the notable expansion of calcium-dependent protein kinases (CDPKs), whose study has revealed roles in gliding motility, microneme secretion, host cell invasion and egress, and parasite differentiation. Microneme secretion has also been shown to depend on the C2 domain containing protein DOC2 in both Plasmodium spp. and Toxoplasma, providing further evidence for the complex transduction of Ca(2+) signals in these organisms. The characterization of these pathways could lead to the discovery of novel drug targets and to a better understanding of the role of Ca(2+) in these parasites.
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Affiliation(s)
- Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
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Toxoplasma, or the discovery of a heterophage. Trends Parasitol 2014; 30:467-9. [PMID: 25178740 DOI: 10.1016/j.pt.2014.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 08/20/2014] [Indexed: 12/23/2022]
Abstract
In mammalian cells, the protozoan pathogen Toxoplasma resides in a nonfusiogenic vacuole that segregates it from host cell resources. How the parasite acquires nutrients and whether it is capable of internalizing host macromolecules have been long-standing mysteries. By exploiting a mutant of Toxoplasma lacking the cathepsin protease L, Dou et al. observed the accumulation of host cytosolic-derived proteins in a multivesicular post-Golgi compartment, which establishes the existence of a functional heterophagic pathway in Toxoplasma.
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