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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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Munera López J, Alonso AM, Figueras MJ, Saldarriaga Cartagena AM, Hortua Triana MA, Diambra L, Vanagas L, Deng B, Moreno SNJ, Angel SO. Analysis of the Interactome of the Toxoplasma gondii Tgj1 HSP40 Chaperone. Proteomes 2023; 11:9. [PMID: 36976888 PMCID: PMC10056330 DOI: 10.3390/proteomes11010009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/20/2023] [Accepted: 02/10/2023] [Indexed: 03/06/2023] Open
Abstract
Toxoplasma gondii is an obligate intracellular apicomplexan that causes toxoplasmosis in humans and animals. Central to its dissemination and pathogenicity is the ability to rapidly divide in the tachyzoite stage and infect any type of nucleated cell. Adaptation to different cell contexts requires high plasticity in which heat shock proteins (Hsps) could play a fundamental role. Tgj1 is a type I Hsp40 of T. gondii, an ortholog of the DNAJA1 group, which is essential during the tachyzoite lytic cycle. Tgj1 consists of a J-domain, ZFD, and DNAJ_C domains with a CRQQ C-terminal motif, which is usually prone to lipidation. Tgj1 presented a mostly cytosolic subcellular localization overlapping partially with endoplasmic reticulum. Protein-protein Interaction (PPI) analysis showed that Tgj1 could be implicated in various biological pathways, mainly translation, protein folding, energy metabolism, membrane transport and protein translocation, invasion/pathogenesis, cell signaling, chromatin and transcription regulation, and cell redox homeostasis among others. The combination of Tgj1 and Hsp90 PPIs retrieved only 70 interactors linked to the Tgj1-Hsp90 axis, suggesting that Tgj1 would present specific functions in addition to those of the Hsp70/Hsp90 cycle, standing out invasion/pathogenesis, cell shape motility, and energy pathway. Within the Hsp70/Hsp90 cycle, translation-associated pathways, cell redox homeostasis, and protein folding were highly enriched in the Tgj1-Hsp90 axis. In conclusion, Tgj1 would interact with a wide range of proteins from different biological pathways, which could suggest a relevant role in them.
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Affiliation(s)
- Jonathan Munera López
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
| | - Andrés Mariano Alonso
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
| | - Maria Julia Figueras
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
| | - Ana María Saldarriaga Cartagena
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
| | - Miryam A. Hortua Triana
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Luis Diambra
- Centro Regional de Estudios Genómicos, Universidad Nacional de La Plata, La Plata 1900, Argentina
| | - Laura Vanagas
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
| | - Bin Deng
- Department of Biology and VBRN, University of Vermont, Burlington, VT 05405, USA
| | - 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
| | - Sergio Oscar Angel
- Laboratorio de Parasitología Molecular, INTECH, CONICET-UNSAM, Av. Intendente Marino Km. 8.2, C.C 164, Chascomús 7130, Argentina
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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 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Huet D, Moreno SNJ. Interorganellar Communication Through Membrane Contact Sites in Toxoplasma Gondii. Contact (Thousand Oaks) 2023; 6:25152564231189064. [PMID: 37560622 PMCID: PMC10408353 DOI: 10.1177/25152564231189064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 08/11/2023]
Abstract
Apicomplexan parasites are a group of protists that cause disease in humans and include pathogens like Plasmodium spp., the causative agent of malaria, and Toxoplasma gondii, the etiological agent of toxoplasmosis and one of the most ubiquitous human parasites in the world. Membrane contact sites (MCSs) are widespread structures within eukaryotic cells but their characterization in apicomplexan parasites is only in its very beginnings. Basic biological features of the T. gondii parasitic cycle support numerous organellar interactions, including the transfer of Ca2+ and metabolites between different compartments. In T. gondii, Ca2+ signals precede a series of interrelated molecular processes occurring in a coordinated manner that culminate in the stimulation of key steps of the parasite life cycle. Calcium transfer from the endoplasmic reticulum to other organelles via MCSs would explain the precision, speed, and efficiency that is needed during the lytic cycle of T. gondii. In this short review, we discuss the implications of these structures in cellular signaling, with an emphasis on their potential role in Ca2+ signaling.
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Affiliation(s)
- Diego Huet
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Sleda MA, Li ZH, Behera R, Baierna B, Li C, Jumpathong J, Malwal SR, Kawamukai M, Oldfield E, Moreno SNJ. The Heptaprenyl Diphosphate Synthase (Coq1) Is the Target of a Lipophilic Bisphosphonate That Protects Mice against Toxoplasma gondii Infection. mBio 2022; 13:e0196622. [PMID: 36129297 PMCID: PMC9600589 DOI: 10.1128/mbio.01966-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/15/2022] [Indexed: 11/20/2022] Open
Abstract
Prenyldiphosphate synthases catalyze the reaction of allylic diphosphates with one or more isopentenyl diphosphate molecules to form compounds such as farnesyl diphosphate, used in, e.g., sterol biosynthesis and protein prenylation, as well as longer "polyprenyl" diphosphates, used in ubiquinone and menaquinone biosynthesis. Quinones play an essential role in electron transport and are associated with the inner mitochondrial membrane due to the presence of the polyprenyl group. In this work, we investigated the synthesis of the polyprenyl diphosphate that alkylates the ubiquinone ring precursor in Toxoplasma gondii, an opportunistic pathogen that causes serious disease in immunocompromised patients and the unborn fetus. The enzyme that catalyzes this early step of the ubiquinone synthesis is Coq1 (TgCoq1), and we show that it produces the C35 species heptaprenyl diphosphate. TgCoq1 localizes to the mitochondrion and is essential for in vitro T. gondii growth. We demonstrate that the growth defect of a T. gondii TgCoq1 mutant is rescued by complementation with a homologous TgCoq1 gene or with a (C45) solanesyl diphosphate synthase from Trypanosoma cruzi (TcSPPS). We find that a lipophilic bisphosphonate (BPH-1218) inhibits T. gondii growth at low-nanomolar concentrations, while overexpression of the TgCoq1 enzyme dramatically reduced growth inhibition by the bisphosphonate. Both the severe growth defect of the mutant and the inhibition by BPH-1218 were rescued by supplementation with a long-chain (C30) ubiquinone (UQ6). Importantly, BPH-1218 also protected mice against a lethal T. gondii infection. TgCoq1 thus represents a potential drug target that could be exploited for improved chemotherapy of toxoplasmosis. IMPORTANCE Millions of people are infected with Toxoplasma gondii, and the available treatment for toxoplasmosis is not ideal. Most of the drugs currently used are only effective for the acute infection, and treatment can trigger serious side effects requiring changes in the therapeutic approach. There is, therefore, a compelling need for safe and effective treatments for toxoplasmosis. In this work, we characterize an enzyme of the mitochondrion of T. gondii that can be inhibited by an isoprenoid pathway inhibitor. We present evidence that demonstrates that inhibition of the enzyme is linked to parasite death. In addition, the inhibitor can protect mice against a lethal dose of T. gondii. Our results thus reveal a promising chemotherapeutic target for the development of new medicines for toxoplasmosis.
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Affiliation(s)
- Melissa A. Sleda
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Ranjan Behera
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Baihetiya Baierna
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Catherine Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Jomkwan Jumpathong
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, Japan
| | - Satish R. Malwal
- Department of Chemistry, University of Illinois at Urbana Champaign, Urbana, Illinois, USA
| | - Makoto Kawamukai
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, Japan
| | - Eric Oldfield
- Department of Chemistry, University of Illinois at Urbana Champaign, Urbana, Illinois, 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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Herneisen AL, Li ZH, Chan AW, Moreno SNJ, Lourido S. Temporal and thermal profiling of the Toxoplasma proteome implicates parasite Protein Phosphatase 1 in the regulation of Ca 2+-responsive pathways. eLife 2022; 11:80336. [PMID: 35976251 PMCID: PMC9436416 DOI: 10.7554/elife.80336] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Apicomplexan parasites cause persistent mortality and morbidity worldwide through diseases including malaria, toxoplasmosis, and cryptosporidiosis. Ca2+ signaling pathways have been repurposed in these eukaryotic pathogens to regulate parasite-specific cellular processes governing the replicative and lytic phases of the infectious cycle, as well as the transition between them. Despite the presence of conserved Ca2+-responsive proteins, little is known about how specific signaling elements interact to impact pathogenesis. We mapped the Ca2+-responsive proteome of the model apicomplexan T. gondii via time-resolved phosphoproteomics and thermal proteome profiling. The waves of phosphoregulation following PKG activation and stimulated Ca2+ release corroborate known physiological changes but identify specific proteins operating in these pathways. Thermal profiling of parasite extracts identified many expected Ca2+-responsive proteins, such as parasite Ca2+-dependent protein kinases. Our approach also identified numerous Ca2+-responsive proteins that are not predicted to bind Ca2+, yet are critical components of the parasite signaling network. We characterized protein phosphatase 1 (PP1) as a Ca2+-responsive enzyme that relocalized to the parasite apex upon Ca2+ store release. Conditional depletion of PP1 revealed that the phosphatase regulates Ca2+ uptake to promote parasite motility. PP1 may thus be partly responsible for Ca2+-regulated serine/threonine phosphatase activity in apicomplexan parasites.
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Affiliation(s)
- Alice L Herneisen
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States
| | - Alex W Chan
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, United States
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, United States
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Baek KH, Phan TN, Malwal SR, Lee H, Li ZH, Moreno SNJ, Oldfield E, No JH. In Vivo Efficacy of SQ109 against Leishmania donovani, Trypanosoma spp. and Toxoplasma gondii and In Vitro Activity of SQ109 Metabolites. Biomedicines 2022; 10:biomedicines10030670. [PMID: 35327472 PMCID: PMC8944987 DOI: 10.3390/biomedicines10030670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 11/16/2022] Open
Abstract
SQ109 is an anti-tubercular drug candidate that has completed Phase IIb/III clinical trials for tuberculosis and has also been shown to exhibit potent in vitro efficacy against protozoan parasites including Leishmania and Trypanosoma cruzi spp. However, its in vivo efficacy against protozoa has not been reported. Here, we evaluated the activity of SQ109 in mouse models of Leishmania, Trypanosoma spp. as well as Toxoplasma infection. In the T. cruzi mouse model, 80% of SQ109-treated mice survived at 40 days post-infection. Even though SQ109 did not cure all mice, these results are of interest since they provide a basis for future testing of combination therapies with the azole posaconazole, which acts synergistically with SQ109 in vitro. We also found that SQ109 inhibited the growth of Toxoplasma gondii in vitro with an IC50 of 1.82 µM and there was an 80% survival in mice treated with SQ109, whereas all untreated animals died 10 days post-infection. Results with Trypanosoma brucei and Leishmania donovani infected mice were not promising with only moderate efficacy. Since SQ109 is known to be extensively metabolized in animals, we investigated the activity in vitro of SQ109 metabolites. Among 16 metabolites, six mono-oxygenated forms were found active across the tested protozoan parasites, and there was a ~6× average decrease in activity of the metabolites as compared to SQ109 which is smaller than the ~25× found with mycobacteria.
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Affiliation(s)
- Kyung-Hwa Baek
- Host-Parasite Research Laboratory, Institut Pasteur Korea, Seongnam-si 13488, Korea; (K.-H.B.); (T.-N.P.); (H.L.)
| | - Trong-Nhat Phan
- Host-Parasite Research Laboratory, Institut Pasteur Korea, Seongnam-si 13488, Korea; (K.-H.B.); (T.-N.P.); (H.L.)
| | - Satish R. Malwal
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; (S.R.M.); (E.O.)
| | - Hyeryon Lee
- Host-Parasite Research Laboratory, Institut Pasteur Korea, Seongnam-si 13488, Korea; (K.-H.B.); (T.-N.P.); (H.L.)
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; (Z.-H.L.); (S.N.J.M.)
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA; (Z.-H.L.); (S.N.J.M.)
| | - Eric Oldfield
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; (S.R.M.); (E.O.)
| | - Joo Hwan No
- Host-Parasite Research Laboratory, Institut Pasteur Korea, Seongnam-si 13488, Korea; (K.-H.B.); (T.-N.P.); (H.L.)
- Correspondence:
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9
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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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: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Vella SA, Moore CA, Li ZH, Hortua Triana MA, Potapenko E, Moreno SNJ. The role of potassium and host calcium signaling in Toxoplasma gondii egress. Cell Calcium 2021; 94:102337. [PMID: 33524795 DOI: 10.1016/j.ceca.2020.102337] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 01/22/2023]
Abstract
Toxoplasma gondii is an obligate intracellular parasite and replicates inside a parasitophorous vacuole (PV) within the host cell. The membrane of the PV (PVM) contains pores that permits for equilibration of ions and small molecules between the host cytosol and the PV lumen. Ca2+ signaling is universal and both T. gondii and its mammalian host cell utilize Ca2+ signals to stimulate diverse cellular functions. Egress of T. gondii from host cells is an essential step for the infection cycle of T. gondii, and a cytosolic Ca2+ increase initiates a Ca2+ signaling cascade that culminates in the stimulation of motility and egress. In this work we demonstrate that intracellular T. gondii tachyzoites are able to take up Ca2+ from the host cytoplasm during host cell signaling events. Both intracellular and extracellular Ca2+ sources are important in reaching a threshold of parasite cytosolic Ca2+ needed for successful egress. Two peaks of Ca2+ were observed in egressing single parasites with the second peak resulting from Ca2+ entry. We patched infected host cells to allow the delivery of precise concentrations of Ca2+ for the stimulation of motility and egress. Using this approach of patching infected host cells, allowed us to determine that increasing the host cytosolic Ca2+ to a specific concentration can trigger egress, which is further accelerated by diminishing the concentration of potassium (K+).
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Affiliation(s)
- Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Microbiology, University of Georgia, United States
| | - Christina A Moore
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Cellular Biology, University of Georgia, Athens, GA, 30602, United States
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States
| | | | - Evgeniy Potapenko
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Cellular Biology, University of Georgia, Athens, GA, 30602, United States.
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12
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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: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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Abstract
Acidocalcisomes are membrane-bounded, electron-dense, acidic organelles, rich in calcium and polyphosphate. These organelles were first described in trypanosomatids and later found from bacteria to human cells. Some of the functions of the acidocalcisome are the storage of cations and phosphorus, participation in pyrophosphate (PPi) and polyphosphate (polyP) metabolism, calcium signaling, maintenance of intracellular pH homeostasis, autophagy, and osmoregulation. Isolation of acidocalcisomes is an important technique for understanding their composition and function. Here, we provide detailed subcellular fractionation protocols using iodixanol gradient centrifugations to isolate high-quality acidocalcisomes from Trypanosoma brucei, which are subsequently validated by electron microscopy, and enzymatic and immunoblot assays with organellar markers.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA.
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA, USA.
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14
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Galaka T, Falcone BN, Li C, Szajnman SH, Moreno SNJ, Docampo R, Rodriguez JB. Synthesis and biological evaluation of 1-alkylaminomethyl-1,1-bisphosphonic acids against Trypanosoma cruzi and Toxoplasma gondii. Bioorg Med Chem 2019; 27:3663-3673. [PMID: 31296439 DOI: 10.1016/j.bmc.2019.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/23/2019] [Accepted: 07/03/2019] [Indexed: 01/15/2023]
Abstract
As an extension of our project aimed at the search for new chemotherapeutic agents against Chagas disease and toxoplasmosis, several 1,1-bisphosphonates were designed, synthesized and biologically evaluated against Trypanosoma cruzi and Toxoplasma gondii, the etiologic agents of these diseases, respectively. In particular, and based on the antiparasitic activity exhibited by 2-alkylaminoethyl-1,1-bisphosphonates targeting farnesyl diphosphate synthase, a series of linear 2-alkylaminomethyl-1,1-bisphosphonic acids (compounds 21-33), that is, the position of the amino group was one carbon closer to the gem-phosphonate moiety, were evaluated as growth inhibitors against the clinically more relevant dividing form (amastigotes) of T. cruzi. Although all of these compounds resulted to be devoid of antiparasitic activity, these results were valuable for a rigorous SAR study. In addition, unexpectedly, the synthetic designed 2-cycloalkylaminoethyl-1,1-bisphosphonic acids 47-49 were free of antiparasitic activity. Moreover, long chain sulfur-containing 1,1-bisphosphonic acids, such as compounds 54-56, 59, turned out to be nanomolar growth inhibitors of tachyzoites of T. gondii. As many bisphosphonate-containing molecules are FDA-approved drugs for the treatment of bone resorption disorders, their potential nontoxicity makes them good candidates to control American trypanosomiasis and toxoplasmosis.
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Affiliation(s)
- Tamila Galaka
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Bruno N Falcone
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Catherine Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Sergio H Szajnman
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Juan B Rodriguez
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
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15
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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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: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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Hortua Triana MA, Márquez-Nogueras KM, Vella SA, Moreno SNJ. Calcium signaling and the lytic cycle of the Apicomplexan parasite Toxoplasma gondii. Biochim Biophys Acta Mol Cell Res 2018; 1865:1846-1856. [PMID: 30992126 DOI: 10.1016/j.bbamcr.2018.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 01/24/2023]
Abstract
Toxoplasma gondii has a complex life cycle involving different hosts and is dependent on fast responses, as the parasite reacts to changing environmental conditions. T. gondii causes disease by lysing the host cells that it infects and it does this by reiterating its lytic cycle, which consists of host cell invasion, replication inside the host cell, and egress causing host cell lysis. Calcium ion (Ca2+) signaling triggers activation of molecules involved in the stimulation and enhancement of each step of the parasite lytic cycle. Ca2+ signaling is essential for the cellular and developmental changes that support T. gondii parasitism. The characterization of the molecular players and pathways directly activated by Ca2+ signaling in Toxoplasma is sketchy and incomplete. The evolutionary distance between Toxoplasma and other eukaryotic model systems makes the comparison sometimes not informative. The advent of new genomic information and new genetic tools applicable for studying Toxoplasma biology is rapidly changing this scenario. The Toxoplasma genome reveals the presence of many genes potentially involved in Ca2+ signaling, even though the role of most of them is not known. The use of Genetically Encoded Calcium Indicators (GECIs) has allowed studies on the role of novel calcium-related proteins on egress, an essential step for the virulence and dissemination of Toxoplasma. In addition, the discovery of new Ca2+ players is generating novel targets for drugs, vaccines, and diagnostic tools and a better understanding of the biology of these parasites.
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Affiliation(s)
| | | | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - 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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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20
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Abstract
Membrane proteins in trypanosomatids are, in general, weakly expressed and confirmation of their subcellular localization frequently requires their overexpression with epitope tags. However, overexpression can lead to mislocalization of the probes. Viswanathan et al. (Nat. Methods, 2015, 12:568) described high performance tags for localization of weakly expressed proteins. We report here the use of these protein tags, named "spaghetti monster," for CRISPR/Cas9-mediated C-terminal endogenous tagging of Trypanosoma cruzi to localize two weakly expressed transient receptor potential channels to acidic compartments. The results indicate that this method will improve the detection of membrane proteins in T. cruzi.
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Affiliation(s)
- Teresa Cruz-Bustos
- 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
| | - Roberto Docampo
- 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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21
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Chao MN, Li C, Storey M, Falcone BN, Szajnman SH, Bonesi SM, Docampo R, Moreno SNJ, Rodriguez JB. Activity of Fluorine-Containing Analogues of WC-9 and Structurally Related Analogues against Two Intracellular Parasites: Trypanosoma cruzi and Toxoplasma gondii. ChemMedChem 2016; 11:2690-2702. [PMID: 27886451 PMCID: PMC5200956 DOI: 10.1002/cmdc.201600505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 10/20/2016] [Indexed: 11/10/2022]
Abstract
Two obligate intracellular parasites, Trypanosoma cruzi, the agent of Chagas disease, and Toxoplasma gondii, an agent of toxoplasmosis, upregulate the mevalonate pathway of their host cells upon infection, which suggests that this host pathway could be a potential drug target. In this work, a number of compounds structurally related to WC-9 (4-phenoxyphenoxyethyl thiocyanate), a known squalene synthase inhibitor, were designed, synthesized, and evaluated for their effect on T. cruzi and T. gondii growth in tissue culture cells. Two fluorine-containing derivatives, the 3-(3-fluorophenoxy)- and 3-(4-fluorophenoxy)phenoxyethyl thiocyanates, exhibited half-maximal effective concentration (EC50 ) values of 1.6 and 4.9 μm, respectively, against tachyzoites of T. gondii, whereas they showed similar potency to WC-9 against intracellular T. cruzi (EC50 values of 5.4 and 5.7 μm, respectively). In addition, 2-[3- (phenoxy)phenoxyethylthio]ethyl-1,1-bisphosphonate, which is a hybrid inhibitor containing 3-phenoxyphenoxy and bisphosphonate groups, has activity against T. gondii proliferation at sub-micromolar levels (EC50 =0.7 μm), which suggests a combined inhibitory effect of the two functional groups.
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Affiliation(s)
- María N. Chao
- M. N. Chao, Dr. B. N. Falcone, Dr. S. H. Szajnman, Prof. Dr. J. B. Rodriguez, Departamento de Química Orgánica and UMYMFOR (CONICET–FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Catherine Li
- C. Li, M. Storey, Prof. Dr. R. Docampo, Prof. Dr. S. N. J. Moreno, Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Melissa Storey
- C. Li, M. Storey, Prof. Dr. R. Docampo, Prof. Dr. S. N. J. Moreno, Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Bruno N. Falcone
- M. N. Chao, Dr. B. N. Falcone, Dr. S. H. Szajnman, Prof. Dr. J. B. Rodriguez, Departamento de Química Orgánica and UMYMFOR (CONICET–FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Sergio H. Szajnman
- M. N. Chao, Dr. B. N. Falcone, Dr. S. H. Szajnman, Prof. Dr. J. B. Rodriguez, Departamento de Química Orgánica and UMYMFOR (CONICET–FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Sergio M. Bonesi
- Prof. Dr. S. M. Bonesi, Departamento de Química Orgánica and CIHIDECAR (CONICET–FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Roberto Docampo
- C. Li, M. Storey, Prof. Dr. R. Docampo, Prof. Dr. S. N. J. Moreno, Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Silvia N. J. Moreno
- C. Li, M. Storey, Prof. Dr. R. Docampo, Prof. Dr. S. N. J. Moreno, Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA
| | - Juan B. Rodriguez
- M. N. Chao, Dr. B. N. Falcone, Dr. S. H. Szajnman, Prof. Dr. J. B. Rodriguez, Departamento de Química Orgánica and UMYMFOR (CONICET–FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
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22
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Moreno SNJ. Keep Up the Good (Bench) Work! Trends Parasitol 2016; 32:579-580. [PMID: 27133187 DOI: 10.1016/j.pt.2016.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 03/31/2016] [Indexed: 11/30/2022]
Abstract
Professor Silvia Moreno studies toxoplasmosis, one of the most common parasitic infections in the world, caused by Toxoplasma gondii. About one-third of the human population is chronically infected with T. gondii cysts, the dormant form of the parasite. Although most immunocompetent infected individuals remain asymptomatic throughout life, serious complications such as loss of vision, mother-to-fetus transmission, and fatal cases can occur. The drugs currently available to treat toxoplasmosis are unable to clear the cyst form of the parasite and have severe side effects like bone marrow suppression and liver toxicity. Silvia has studied parasite metabolism for more than 20 years and has been at the University of Georgia since 2005. Her goal is to uncover unique aspects of parasite metabolism that can be targeted for designing more effective, less toxic drugs against T. gondii. In this short interview, Silvia highlights the importance of staying true to one's identity and of learning to say 'no', and advises young researchers to not stay away from the bench.
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Affiliation(s)
- S N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA; Department of Cellular Biology, University of Georgia, Athens, GA, USA.
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23
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Sidik SM, Hortua Triana MA, Paul AS, El Bakkouri M, Hackett CG, Tran F, Westwood NJ, Hui R, Zuercher WJ, Duraisingh MT, Moreno SNJ, Lourido S. Using a Genetically Encoded Sensor to Identify Inhibitors of Toxoplasma gondii Ca2+ Signaling. J Biol Chem 2016; 291:9566-80. [PMID: 26933036 PMCID: PMC4850295 DOI: 10.1074/jbc.m115.703546] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 11/27/2022] Open
Abstract
The life cycles of apicomplexan parasites progress in accordance with fluxes in cytosolic Ca2+. Such fluxes are necessary for events like motility and egress from host cells. We used genetically encoded Ca2+ indicators (GCaMPs) to develop a cell-based phenotypic screen for compounds that modulate Ca2+ signaling in the model apicomplexan Toxoplasma gondii. In doing so, we took advantage of the phosphodiesterase inhibitor zaprinast, which we show acts in part through cGMP-dependent protein kinase (protein kinase G; PKG) to raise levels of cytosolic Ca2+. We define the pool of Ca2+ regulated by PKG to be a neutral store distinct from the endoplasmic reticulum. Screening a library of 823 ATP mimetics, we identify both inhibitors and enhancers of Ca2+ signaling. Two such compounds constitute novel PKG inhibitors and prevent zaprinast from increasing cytosolic Ca2+. The enhancers identified are capable of releasing intracellular Ca2+ stores independently of zaprinast or PKG. One of these enhancers blocks parasite egress and invasion and shows strong antiparasitic activity against T. gondii. The same compound inhibits invasion of the most lethal malaria parasite, Plasmodium falciparum. Inhibition of Ca2+-related phenotypes in these two apicomplexan parasites suggests that depletion of intracellular Ca2+ stores by the enhancer may be an effective antiparasitic strategy. These results establish a powerful new strategy for identifying compounds that modulate the essential parasite signaling pathways regulated by Ca2+, underscoring the importance of these pathways and the therapeutic potential of their inhibition.
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Affiliation(s)
- Saima M Sidik
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Miryam A Hortua Triana
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Aditya S Paul
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Majida El Bakkouri
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Caroline G Hackett
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Fanny Tran
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Nicholas J Westwood
- the School of Chemistry and Biomedical Sciences Research Complex, University of St. Andrews and EaStCHEM, North Haugh, St. Andrews, Fife KY16 9ST, Scotland, United Kingdom, and
| | - Raymond Hui
- the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - William J Zuercher
- the Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Manoj T Duraisingh
- the Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Silvia N J Moreno
- the Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Sebastian Lourido
- From the Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142,
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24
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Borges-Pereira L, Budu A, McKnight CA, Moore CA, Vella SA, Hortua Triana MA, Liu J, Garcia CRS, Pace DA, Moreno SNJ. Calcium Signaling throughout the Toxoplasma gondii Lytic Cycle: A STUDY USING GENETICALLY ENCODED CALCIUM INDICATORS. J Biol Chem 2015; 290:26914-26926. [PMID: 26374900 DOI: 10.1074/jbc.m115.652511] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Indexed: 11/06/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasite that invades host cells, creating a parasitophorous vacuole where it communicates with the host cell cytosol through the parasitophorous vacuole membrane. The lytic cycle of the parasite starts with its exit from the host cell followed by gliding motility, conoid extrusion, attachment, and invasion of another host cell. Here, we report that Ca(2+) oscillations occur in the cytosol of the parasite during egress, gliding, and invasion, which are critical steps of the lytic cycle. Extracellular Ca(2+) enhances each one of these processes. We used tachyzoite clonal lines expressing genetically encoded calcium indicators combined with host cells expressing transiently expressed calcium indicators of different colors, and we measured Ca(2+) changes in both parasites and host simultaneously during egress. We demonstrated a link between cytosolic Ca(2+) oscillations in the host and in the parasite. Our approach also allowed us to measure two new features of motile parasites, which were enhanced by Ca(2+) influx. This is the first study showing, in real time, Ca(2+) signals preceding egress and their direct link with motility, an essential virulence trait.
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Affiliation(s)
- Lucas Borges-Pereira
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Alexandre Budu
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Ciara A McKnight
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Christina A Moore
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602; Department of Cellular Biology, University of Georgia, Athens, Georgia 30602
| | - Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Jing Liu
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Celia R S Garcia
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602
| | - Douglas A Pace
- 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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25
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Chao MN, Matiuzzi CE, Storey M, Li C, Szajnman SH, Docampo R, Moreno SNJ, Rodriguez JB. Aryloxyethyl Thiocyanates Are Potent Growth Inhibitors of Trypanosoma cruzi and Toxoplasma gondii. ChemMedChem 2015; 10:1094-108. [PMID: 25914175 PMCID: PMC4447534 DOI: 10.1002/cmdc.201500100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Indexed: 12/13/2022]
Abstract
As a part of our project aimed at searching for new safe chemotherapeutic agents against parasitic diseases, several compounds structurally related to the antiparasitic agent WC-9 (4-phenoxyphenoxyethyl thiocyanate), which were modified at the terminal phenyl ring, were designed, synthesized, and evaluated as growth inhibitors against Trypanosoma cruzi, the etiological agent of Chagas disease, and Toxoplasma gondii, the parasite responsible of toxoplasmosis. Most of the synthetic analogues exhibited similar antiparasitic activity and were slightly more potent than our lead WC-9. For example, two trifluoromethylated derivatives exhibited ED50 values of 10.0 and 9.2 μM against intracellular T. cruzi, whereas they showed potent action against tachyzoites of T. gondii (ED50 values of 1.6 and 1.9 μM against T. gondii). In addition, analogues of WC-9 in which the terminal aryl group is in the meta position with respect to the alkyl chain bearing the thiocyanate group showed potent inhibitory action against both T. cruzi and T. gondii at the very low micromolar range, which suggests that a para-phenyl substitution pattern is not necessary for biological activity.
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Affiliation(s)
- María N Chao
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires (Argentina)
| | - Carolina Exeni Matiuzzi
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires (Argentina)
| | - Melissa Storey
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, 30602 (USA)
| | - Catherine Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, 30602 (USA)
| | - Sergio H Szajnman
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires (Argentina)
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, 30602 (USA)
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA, 30602 (USA)
| | - Juan B Rodriguez
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires (Argentina).
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26
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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: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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27
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Huang G, Ulrich PN, Storey M, Johnson D, Tischer J, Tovar JA, Moreno SNJ, Orlando R, Docampo R. Proteomic analysis of the acidocalcisome, an organelle conserved from bacteria to human cells. PLoS Pathog 2014; 10:e1004555. [PMID: 25503798 PMCID: PMC4263762 DOI: 10.1371/journal.ppat.1004555] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 11/05/2014] [Indexed: 01/12/2023] Open
Abstract
Acidocalcisomes are acidic organelles present in a diverse range of organisms from bacteria to human cells. In this study acidocalcisomes were purified from the model organism Trypanosoma brucei, and their protein composition was determined by mass spectrometry. The results, along with those that we previously reported, show that acidocalcisomes are rich in pumps and transporters, involved in phosphate and cation homeostasis, and calcium signaling. We validated the acidocalcisome localization of seven new, putative, acidocalcisome proteins (phosphate transporter, vacuolar H+-ATPase subunits a and d, vacuolar iron transporter, zinc transporter, polyamine transporter, and acid phosphatase), confirmed the presence of six previously characterized acidocalcisome proteins, and validated the localization of five novel proteins to different subcellular compartments by expressing them fused to epitope tags in their endogenous loci or by immunofluorescence microscopy with specific antibodies. Knockdown of several newly identified acidocalcisome proteins by RNA interference (RNAi) revealed that they are essential for the survival of the parasites. These results provide a comprehensive insight into the unique composition of acidocalcisomes of T. brucei, an important eukaryotic pathogen, and direct evidence that acidocalcisomes are especially adapted for the accumulation of polyphosphate.
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Affiliation(s)
- Guozhong Huang
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Paul N Ulrich
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Melissa Storey
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Darryl Johnson
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Julie Tischer
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Javier A Tovar
- Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Ron Orlando
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
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28
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Liu J, Pace D, Dou Z, King TP, Guidot D, Li ZH, Carruthers VB, Moreno SNJ. A vacuolar-H(+) -pyrophosphatase (TgVP1) is required for microneme secretion, host cell invasion, and extracellular survival of Toxoplasma gondii. Mol Microbiol 2014; 93:698-712. [PMID: 24975633 DOI: 10.1111/mmi.12685] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
The vacuolar proton pyrophosphatase (H(+) -PPase) of Toxoplasma gondii (TgVP1), a membrane proton pump, localizes to acidocalcisomes and a novel lysosome-like compartment termed plant-like vacuole (PLV) or vacuolar compartment (VAC). We report the characterization of a T. gondii null mutant for the TgVP1 gene. Propagation of these mutants decreased significantly because of deficient attachment and invasion of host cells, which correlated with deficient microneme secretion. Processing of cathepsin L (CPL) in these mutants was deficient only when the parasites were incubated in the presence of low concentrations of the vacuolar H(+) -ATPase (V-H(+) -ATPase) inhibitor bafilomycin A1 , suggesting that either TgVP1 or the T. gondii V-H(+) -ATPase (TgVATPase) are sufficient to support CPL processing. The lack of TgVP1 did not affect processing of micronemal proteins, indicating that it does not contribute to proMIC maturations. The TgVP1 null mutants were more sensitive to extracellular conditions and were less virulent in mice. We demonstrate that T. gondii tachyzoites possess regulatory volume decrease capability during hypo-osmotic stress and this ability is impaired in TgVP1 null mutants implicating TgVP1 in osmoregulation. We hypothesize that osmoregulation is needed for host cell invasion and that TgVP1 plays a role during the normal lytic cycle of T. gondii.
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Affiliation(s)
- Jing Liu
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, GA, 30602-7400, USA; College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
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29
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Tang Q, Andenmatten N, Hortua Triana MA, Deng B, Meissner M, Moreno SNJ, Ballif BA, Ward GE. Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii. Mol Biol Cell 2014; 25:2579-91. [PMID: 24989796 PMCID: PMC4148248 DOI: 10.1091/mbc.e13-11-0648] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Myosin A, an unconventional class XIV myosin of the protozoan parasite Toxoplasma gondii, undergoes calcium-dependent phosphorylation, providing a mechanism by which the parasite can regulate motility-based processes such as escape from the infected host cell at the end of the parasite's lytic cycle. Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
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Affiliation(s)
- Qing Tang
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
| | - Nicole Andenmatten
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bin Deng
- Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT 05405 Department of Biology, University of Vermont, Burlington, VT 05405
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
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30
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Pace DA, McKnight CA, Liu J, Jimenez V, Moreno SNJ. Calcium entry in Toxoplasma gondii and its enhancing effect of invasion-linked traits. J Biol Chem 2014; 289:19637-47. [PMID: 24867952 DOI: 10.1074/jbc.m114.565390] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
During invasion and egress from their host cells, Apicomplexan parasites face sharp changes in the surrounding calcium ion (Ca(2+)) concentration. Our work with Toxoplasma gondii provides evidence for Ca(2+) influx from the extracellular milieu leading to cytosolic Ca(2+) increase and enhancement of virulence traits, such as gliding motility, conoid extrusion, microneme secretion, and host cell invasion. Assays of Mn(2+) and Ba(2+) uptake do not support a canonical store-regulated Ca(2+) entry mechanism. Ca(2+) entry was blocked by the L-type Ca(2+) channel inhibitor nifedipine and stimulated by the increase in cytosolic Ca(2+) and by the specific L-type Ca(2+) channel agonist Bay K-8644. Our results demonstrate that Ca(2+) entry is critical for parasite virulence. We propose a regulated Ca(2+) entry mechanism activated by cytosolic Ca(2+) that has an enhancing effect on invasion-linked traits.
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Affiliation(s)
- Douglas A Pace
- From the Center for Tropical and Emerging Global Diseases and
| | - Ciara A McKnight
- From the Center for Tropical and Emerging Global Diseases and the Department of Cellular Biology, University of Georgia, Athens, Georgia 30602 and
| | - Jing Liu
- From the Center for Tropical and Emerging Global Diseases and the College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | | | - Silvia N J Moreno
- From the Center for Tropical and Emerging Global Diseases and the Department of Cellular Biology, University of Georgia, Athens, Georgia 30602 and
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31
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Ferrer-Casal M, Li C, Galizzi M, Stortz CA, Szajnman SH, Docampo R, Moreno SNJ, Rodriguez JB. New insights into molecular recognition of 1,1-bisphosphonic acids by farnesyl diphosphate synthase. Bioorg Med Chem 2013; 22:398-405. [PMID: 24300918 DOI: 10.1016/j.bmc.2013.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 10/28/2013] [Accepted: 11/05/2013] [Indexed: 10/26/2022]
Abstract
As part of our project pointed at the search of new antiparasitic agents against American trypanosomiasis (Chagas disease) and toxoplasmosis a series of 2-alkylaminoethyl-1-hydroxy-1,1-bisphosphonic acids has been designed, synthesized and biologically evaluated against the etiologic agents of these parasitic diseases, Trypanosoma cruzi and Toxoplasma gondii, respectively, and also towards their target enzymes, T. cruzi and T. gondii farnesyl pyrophosphate synthase (FPPS), respectively. Surprisingly, while most pharmacologically active bisphosphonates have a hydroxyl group at the C-1 position, the additional presence of an amino group at C-3 resulted in decreased activity towards either T. cruzi cells or TcFPPS. Density functional theory calculations justify this unexpected behavior. Although these compounds were devoid of activity against T. cruzi cells and TcFPPS, they were efficient growth inhibitors of tachyzoites of T. gondii. This activity was associated with a potent inhibition of the enzymatic activity of TgFPPS. Compound 28 arises as a main example of this family of compounds exhibiting an ED₅₀ value of 4.7 μM against tachyzoites of T. gondii and an IC₅₀ of 0.051 μM against TgFPPS.
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Affiliation(s)
- Mariana Ferrer-Casal
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Catherine Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Melina Galizzi
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Carlos A Stortz
- Departamento de Química Orgánica and CIHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Sergio H Szajnman
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Juan B Rodriguez
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
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32
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Li ZH, Ramakrishnan S, Striepen B, Moreno SNJ. Toxoplasma gondii relies on both host and parasite isoprenoids and can be rendered sensitive to atorvastatin. PLoS Pathog 2013; 9:e1003665. [PMID: 24146616 PMCID: PMC3798403 DOI: 10.1371/journal.ppat.1003665] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 08/14/2013] [Indexed: 01/03/2023] Open
Abstract
Intracellular pathogens have complex metabolic interactions with their host cells to ensure a steady supply of energy and anabolic building blocks for rapid growth. Here we use the obligate intracellular parasite Toxoplasma gondii to probe this interaction for isoprenoids, abundant lipidic compounds essential to many cellular processes including signaling, trafficking, energy metabolism, and protein translation. Synthesis of precursors for isoprenoids in Apicomplexa occurs in the apicoplast and is essential. To synthesize longer isoprenoids from these precursors, T. gondii expresses a bifunctional farnesyl diphosphate/geranylgeranyl diphosphate synthase (TgFPPS). In this work we construct and characterize T. gondii null mutants for this enzyme. Surprisingly, these mutants have only a mild growth phenotype and an isoprenoid composition similar to wild type parasites. However, when extracellular, the loss of the enzyme becomes phenotypically apparent. This strongly suggests that intracellular parasite salvage FPP and/or geranylgeranyl diphosphate (GGPP) from the host. We test this hypothesis using inhibitors of host cell isoprenoid synthesis. Mammals use the mevalonate pathway, which is susceptible to statins. We document strong synergy between statin treatment and pharmacological or genetic interference with the parasite isoprenoid pathway. Mice can be cured with atorvastatin (Lipitor) from a lethal infection with the TgFPPs mutant. We propose a double-hit strategy combining inhibitors of host and parasite pathways as a novel therapeutic approach against Apicomplexan parasites. Toxoplasma gondii is an obligate intracellular parasite and is not able to replicate outside the host cell. The parasite lives in a specialized parasitophorous vacuole in contact with the host cytoplasm through the parasitophorous vacuole membrane. It is highly likely that a very active exchange of metabolites occurs between parasite and host cell. We present evidence for this exchange for isoprenoids, abundant lipidic compounds essential to many cellular processes including signaling, trafficking, energy metabolism, and protein translation. Our work shows that intracellular T. gondii tachyzoites are able to salvage farnesyl diphosphate (FPP) and/or geranylgeranyl diphosphate (GGPP) from the host, and the parasite is able to grow even when its endogenous production is shut down. However, when extracellular, the parasite depends entirely on its own production of isoprenoids. We propose to use a combination of inhibitors that would hit both the host and the parasite pathways as a novel therapeutic approach against Toxoplasma gondii that could also work against other Apicomplexan parasites.
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Affiliation(s)
- Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Srinivasan Ramakrishnan
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Boris Striepen
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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33
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Affiliation(s)
- Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA.
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34
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De Napoli MG, de Miguel N, Lebrun M, Moreno SNJ, Angel SO, Corvi MM. N-terminal palmitoylation is required for Toxoplasma gondii HSP20 inner membrane complex localization. Biochim Biophys Acta 2013; 1833:1329-37. [PMID: 23485398 DOI: 10.1016/j.bbamcr.2013.02.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/14/2013] [Accepted: 02/19/2013] [Indexed: 12/11/2022]
Abstract
Toxoplasma gondii is an obligate intracellular parasite and the causative agent of toxoplasmosis. Protein palmitoylation is known to play roles in signal transduction and in enhancing the hydrophobicity of proteins thus contributing to their membrane association. Global inhibition of protein palmitoylation has been shown to affect T. gondii physiology and invasion of the host cell. However, the proteins affected by this modification have been understudied. This paper shows that the small heat shock protein 20 from T. gondii (TgHSP20) is synthesized as a mature protein in the cytosol and is palmitoylated in three cysteine residues. However, its localization at the inner membrane complex (IMC) is dependent only on N-terminal palmitoylation. Absence or incomplete N-terminal palmitoylation causes TgHSP20 to partially accumulate in a membranous structure. Interestingly, TgHSP20 palmitoylation is not responsible for its interaction with the daughter cells IMCs. Together, our data describe the importance of palmitoylation in protein targeting to the IMC in T. gondii.
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Affiliation(s)
- M G De Napoli
- Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas, Provincia de Buenos Aires, Argentina
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35
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Recher M, Barboza AP, Li ZH, Galizzi M, Ferrer-Casal M, Szajnman SH, Docampo R, Moreno SNJ, Rodriguez JB. Design, synthesis and biological evaluation of sulfur-containing 1,1-bisphosphonic acids as antiparasitic agents. Eur J Med Chem 2012; 60:431-40. [PMID: 23318904 DOI: 10.1016/j.ejmech.2012.12.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 10/27/2022]
Abstract
As part of our efforts aimed at searching for new antiparasitic agents, 2-alkylmercaptoethyl-1,1-bisphosphonate derivatives were synthesized and evaluated against Trypanosoma cruzi, the etiologic agent of Chagas disease, and Toxoplasma gondii, the responsible agent for toxoplasmosis. Many of these sulfur-containing bisphosphonates were potent inhibitors against the intracellular form of T. cruzi, the clinically more relevant replicative form of this parasite, and tachyzoites of T. gondii targeting T. cruzi or T. gondii farnesyl diphosphate synthases (FPPSs), which constitute valid targets for the chemotherapy of these parasitic diseases. Interestingly, long chain length sulfur-containing bisphosphonates emerged as relevant antiparasitic agents. Taking compounds 37, 38, and 39 as representative members of this class of drugs, they exhibited ED(50) values of 15.8 μM, 12.8 μM, and 22.4 μM, respectively, against amastigotes of T. cruzi. These cellular activities matched the inhibition of the enzymatic activity of the target enzyme (TcFPPS) having IC(50) values of 6.4 μM, 1.7 μM, and 0.097 μM, respectively. In addition, these compounds were potent anti-Toxoplasma agents. They had ED(50) values of 2.6 μM, 1.2 μM, and 1.8 μM, respectively, against T. gondii tachyzoites, while they exhibited a very potent inhibitory action against the target enzyme (TgFPPS) showing IC(50) values of 0.024 μM, 0.025 μM, and 0.021 μM, respectively. Bisphosphonates bearing a sulfoxide unit at C-3 were also potent anti-Toxoplasma agents, particularly those bearing long aliphatic chains such as 43-45, which were also potent antiproliferative drugs against tachyzoites of T. gondii. These compounds inhibited the enzymatic activity of the target enzyme (TgFPPS) at the very low nanomolar range. These bisphosphonic acids have very good prospective not only as lead drugs but also as potential chemotherapeutic agents.
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Affiliation(s)
- Marion Recher
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
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36
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Li ZH, Cintrón R, Koon NA, Moreno SNJ. The N-terminus and the chain-length determination domain play a role in the length of the isoprenoid product of the bifunctional Toxoplasma gondii farnesyl diphosphate synthase. Biochemistry 2012; 51:7533-40. [PMID: 22931372 DOI: 10.1021/bi3005335] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Toxoplasma gondii possesses a bifunctional farnesyl diphosphate (FPP)/geranylgeranyl diphosphate (GGPP) synthase (TgFPPS) that synthesizes C(15) and C(20) isoprenoid diphosphates from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). This enzyme has a unique arrangement of the fourth and fifth amino acid upstream from the first aspartic rich motif (FARM) where the fourth amino acid is aromatic and the fifth is a cysteine. We mutated these amino acids, converting the enzyme to an absolute FPPS by changing the cysteine to a tyrosine. The enzyme could be converted to an absolute GGPPS by changing both the fourth and fifth amino acids to alanines. We also constructed four mutated TgFPPSs whose regions around the first aspartate rich motif were replaced with the corresponding regions of FPP synthases from Arabidopsis thaliana or Saccharomyces cerevisiae or with the corresponding regions of GGPP synthases from Homo sapiens or S. cerevisiae. We determined that the presence of a cysteine at the fifth position is essential for the TgFPPS bifunctionality. We also found that the length of the N-terminal domain plays a role in determining the specificity and the length of the isoprenoid product. Phylogenetic analysis supports the grouping of this enzyme with other type I FPPSs, but the biochemical data indicate that TgFPPS has unique characteristics that differentiate it from mammalian FPPSs and GGPPSs and is therefore an important drug target.
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Affiliation(s)
- Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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37
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Szajnman SH, Rosso VS, Malayil L, Smith A, Moreno SNJ, Docampo R, Rodriguez JB. 1-(Fluoroalkylidene)-1,1-bisphosphonic acids are potent and selective inhibitors of the enzymatic activity of Toxoplasma gondii farnesyl pyrophosphate synthase. Org Biomol Chem 2012; 10:1424-33. [PMID: 22215028 PMCID: PMC3458512 DOI: 10.1039/c1ob06602a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
α-Fluorinated-1,1-bisphosphonic acids derived from fatty acids were designed, synthesized and biologically evaluated against Trypanosoma cruzi, the etiologic agent of Chagas disease, and against Toxoplasma gondii, the agent responsible for toxoplasmosis, and also towards the target parasitic enzymes farnesyl pyrophosphate synthase of T. cruzi (TcFPPS) and T. gondii (TgFPPS). Interestingly, 1-fluorononylidene-1,1-bisphosphonic acid (compound 43) proved to be an extremely potent inhibitor of the enzymatic activity of TgFPPS at the low nanomolar range, exhibiting an IC(50) of 30 nM. This compound was two-fold more potent than risedronate (IC(50) = 74 nM) that was taken as a positive control. This enzymatic activity was associated with a strong cell growth inhibition against tachyzoites of T. gondii, with an IC(50) value of 2.7 μM.
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Affiliation(s)
- Sergio H Szajnman
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
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38
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Pace DA, Fang J, Cintron R, Docampo MD, Moreno SNJ. Overexpression of a cytosolic pyrophosphatase (TgPPase) reveals a regulatory role of PP(i) in glycolysis for Toxoplasma gondii. Biochem J 2011; 440:229-40. [PMID: 21831041 PMCID: PMC4874478 DOI: 10.1042/bj20110641] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PP(i) is a critical element of cellular metabolism as both an energy donor and as an allosteric regulator of several metabolic pathways. The apicomplexan parasite Toxoplasma gondii uses PP(i) in place of ATP as an energy donor in at least two reactions: the glycolytic PP(i)-dependent PFK (phosphofructokinase) and V-H(+)-PPase [vacuolar H(+)-translocating PPase (pyrophosphatase)]. In the present study, we report the cloning, expression and characterization of cytosolic TgPPase (T. gondii soluble PPase). Amino acid sequence alignment and phylogenetic analysis indicates that the gene encodes a family I soluble PPase. Overexpression of the enzyme in extracellular tachyzoites led to a 6-fold decrease in the cytosolic concentration of PP(i) relative to wild-type strain RH tachyzoites. Unexpectedly, this subsequent reduction in PP(i) was associated with a higher glycolytic flux in the overexpressing mutants, as evidenced by higher rates of proton and lactate extrusion. In addition to elevated glycolytic flux, TgPPase-overexpressing tachyzoites also possessed higher ATP concentrations relative to wild-type RH parasites. These results implicate PP(i) as having a significant regulatory role in glycolysis and, potentially, other downstream processes that regulate growth and cell division.
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Affiliation(s)
- Douglas A Pace
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
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39
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Abstract
Acidocalcisomes of Trypanosoma cruzi are acidic calcium-containing organelles rich in phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Acidification of the organelles is driven by vacuolar proton pumps, one of which, the vacuolar-type proton pyrophosphatase, is absent in mammalian cells. A calcium ATPase is involved in calcium uptake, and an aquaporin is important for water transport. Enzymes involved in the synthesis and degradation of PPi and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, participate in PP(i) and poly P metabolism and volume regulation and are essential for virulence. A signalling pathway involving cyclic AMP generation is important for fusion of acidocalcisomes to the contractile vacuole complex, transference of aquaporin and volume regulation. This pathway is an excellent target for chemotherapy as shown by the effects of phosphodiesterase C inhibitors on parasite survival.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, GA, USA
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40
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Nair SC, Brooks CF, Goodman CD, Sturm A, Strurm A, McFadden GI, Sundriyal S, Anglin JL, Song Y, Moreno SNJ, Striepen B. Apicoplast isoprenoid precursor synthesis and the molecular basis of fosmidomycin resistance in Toxoplasma gondii. ACTA ACUST UNITED AC 2011; 208:1547-59. [PMID: 21690250 PMCID: PMC3135366 DOI: 10.1084/jem.20110039] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Expression of a bacterial transporter protein in Toxoplasma gondii results in parasite susceptibility to Formidomycin, a drug targeting isoprenoid precursor synthesis. Apicomplexa are important pathogens that include the causative agents of malaria, toxoplasmosis, and cryptosporidiosis. Apicomplexan parasites contain a relict chloroplast, the apicoplast. The apicoplast is indispensable and an attractive drug target. The apicoplast is home to a 1-deoxy-d-xylulose-5-phosphate (DOXP) pathway for the synthesis of isoprenoid precursors. This pathway is believed to be the most conserved function of the apicoplast, and fosmidomycin, a specific inhibitor of the pathway, is an effective antimalarial. Surprisingly, fosmidomycin has no effect on most other apicomplexans. Using Toxoplasma gondii, we establish that the pathway is essential in parasites that are highly fosmidomycin resistant. We define the molecular basis of resistance and susceptibility, experimentally testing various host and parasite contributions in T. gondii and Plasmodium. We demonstrate that in T. gondii the parasite plasma membrane is a critical barrier to drug uptake. In strong support of this hypothesis, we engineer de novo drug-sensitive T. gondii parasites by heterologous expression of a bacterial transporter protein. Mice infected with these transgenic parasites can now be cured from a lethal challenge with fosmidomycin. We propose that the varied extent of metabolite exchange between host and parasite is a crucial determinator of drug susceptibility and a predictor of future resistance.
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Affiliation(s)
- Sethu C Nair
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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41
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Francia ME, Wicher S, Pace DA, Sullivan J, Moreno SNJ, Arrizabalaga G. A Toxoplasma gondii protein with homology to intracellular type Na⁺/H⁺ exchangers is important for osmoregulation and invasion. Exp Cell Res 2011; 317:1382-96. [PMID: 21501607 DOI: 10.1016/j.yexcr.2011.03.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 03/31/2011] [Accepted: 03/31/2011] [Indexed: 01/16/2023]
Abstract
The obligate intracellular parasite Toxoplasma gondii is exposed to a variety of physiological conditions while propagating in an infected organism. The mechanisms by which Toxoplasma overcomes these dramatic changes in its environment are not known. In yeast and plants, ion detoxification and osmotic regulation are controlled by vacuolar compartments. A novel compartment named the plant-like vacuole or vacuolar compartment (PLV/VAC) has recently been described in T.gondii, which could potentially protect extracellular tachyzoites against salt and other ionic stresses. Here, we report the molecular characterization of the vacuolar type Na(+)/H(+) exchanger in T. gondii, TgNHE3, and its co-localization with the PLV/VAC proton-pyrophosphatase (TgVP1). We have created a TgNHE3 knockout strain, which is more sensitive to hyperosmotic shock and toxic levels of sodium, possesses a higher intracellular Ca(2+) concentration [Ca(2+)](i), and exhibits a reduced host invasion efficiency. The defect in invasion correlates with a measurable reduction in the secretion of the adhesin TgMIC2. Overall, our results suggest that the PLV/VAC has functions analogous to those of the vacuolar compartments of plants and yeasts, providing the parasite with a mechanism to resist ionic fluctuations and, potentially, regulate protein trafficking.
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Affiliation(s)
- Maria E Francia
- Department of Biological Sciences, University of Idaho, Life Sciences South Room 142, Moscow, ID 83844, USA
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42
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Rosso VS, Szajnman SH, Malayil L, Galizzi M, Moreno SNJ, Docampo R, Rodriguez JB. Synthesis and biological evaluation of new 2-alkylaminoethyl-1,1-bisphosphonic acids against Trypanosoma cruzi and Toxoplasma gondii targeting farnesyl diphosphate synthase. Bioorg Med Chem 2011; 19:2211-7. [PMID: 21419634 PMCID: PMC3071284 DOI: 10.1016/j.bmc.2011.02.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 02/16/2011] [Accepted: 02/18/2011] [Indexed: 10/18/2022]
Abstract
The effect of long-chain 2-alkylaminoethyl-1,1-bisphosphonates against proliferation of the clinically more relevant form of Trypanosoma cruzi, the etiologic agent of American trypanosomiasis (Chagas' disease), and against tachyzoites of Toxoplasma gondii was investigated. Particularly, compound 26 proved to be an extremely potent inhibitor against the intracellular form of T. cruzi, exhibiting IC(50) values at the nanomolar range. This cellular activity was associated with a strong inhibition of the enzymatic activity of T. cruzi farnesyl diphosphate synthase (TcFPPS), which constitutes a valid target for Chagas' disease chemotherapy. Compound 26 was an effective agent against T. cruzi (amastigotes) exhibiting an IC(50) value of 0.67 μM, while this compound showed an IC(50) value of 0.81 μM against the target enzyme TcFPPS. This drug was less effective against the enzymatic activity of T. cruzi solanesyl diphosphate synthase TcSPPS showing an IC(50) value of 3.2 μM. Interestingly, compound 26 was also very effective against T. gondii (tachyzoites) exhibiting IC(50) values of 6.23 μM. This cellular activity was also related to the inhibition of the enzymatic activity towards the target enzyme TgFPPS (IC(50)=0.093 μM) As bisphosphonate-containing compounds are FDA-approved drugs for the treatment of bone resorption disorders, their potential low toxicity makes them good candidates to control different tropical diseases.
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Affiliation(s)
- Valeria S Rosso
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
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43
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Ulrich PN, Jimenez V, Park M, Martins VP, Atwood J, Moles K, Collins D, Rohloff P, Tarleton R, Moreno SNJ, Orlando R, Docampo R. Identification of contractile vacuole proteins in Trypanosoma cruzi. PLoS One 2011; 6:e18013. [PMID: 21437209 PMCID: PMC3060929 DOI: 10.1371/journal.pone.0018013] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
Contractile vacuole complexes are critical components of cell volume regulation
and have been shown to have other functional roles in several free-living
protists. However, very little is known about the functions of the contractile
vacuole complex of the parasite Trypanosoma cruzi, the
etiologic agent of Chagas disease, other than a role in osmoregulation.
Identification of the protein composition of these organelles is important for
understanding their physiological roles. We applied a combined proteomic and
bioinfomatic approach to identify proteins localized to the contractile vacuole.
Proteomic analysis of a T. cruzi fraction enriched for
contractile vacuoles and analyzed by one-dimensional gel electrophoresis and
LC-MS/MS resulted in the addition of 109 newly detected proteins to the group of
expressed proteins of epimastigotes. We also identified different peptides that
map to at least 39 members of the dispersed gene family 1 (DGF-1) providing
evidence that many members of this family are simultaneously expressed in
epimastigotes. Of the proteins present in the fraction we selected several
homologues with known localizations in contractile vacuoles of other organisms
and others that we expected to be present in these vacuoles on the basis of
their potential roles. We determined the localization of each by expression as
GFP-fusion proteins or with specific antibodies. Six of these putative proteins
(Rab11, Rab32, AP180, ATPase subunit B, VAMP1, and phosphate transporter)
predominantly localized to the vacuole bladder. TcSNARE2.1, TcSNARE2.2, and
calmodulin localized to the spongiome. Calmodulin was also cytosolic. Our
results demonstrate the utility of combining subcellular fractionation,
proteomic analysis, and bioinformatic approaches for localization of organellar
proteins that are difficult to detect with whole cell methodologies. The CV
localization of the proteins investigated revealed potential novel roles of
these organelles in phosphate metabolism and provided information on the
potential participation of adaptor protein complexes in their biogenesis.
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Affiliation(s)
- Paul N. Ulrich
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Veronica Jimenez
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Miyoung Park
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Vicente P. Martins
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - James Atwood
- Complex Carbohydrate Research Center,
University of Georgia, Athens, Georgia, United States of America
| | - Kristen Moles
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Dalis Collins
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Peter Rohloff
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Rick Tarleton
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
| | - Ron Orlando
- Complex Carbohydrate Research Center,
University of Georgia, Athens, Georgia, United States of America
| | - Roberto Docampo
- Center for Tropical and Emerging Global
Diseases and Department of Cellular Biology, University of Georgia, Athens,
Georgia, United States of America
- * E-mail:
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Rooney PJ, Ayong L, Tobin CM, Moreno SNJ, Knoll LJ. TgVTC2 is involved in polyphosphate accumulation in Toxoplasma gondii. Mol Biochem Parasitol 2010; 176:121-6. [PMID: 21195114 DOI: 10.1016/j.molbiopara.2010.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 10/18/2022]
Abstract
Polyphosphate is found in every cell, having roles in diverse processes, including differentiation and response to stress. In this study, we characterize a Toxoplasma gondii mutant containing an insertion within the carboxy-terminal end of a homolog of Saccharomyces cerevisiae Vtc2p, a component of the polyphosphate synthetic machinery. Locus TgVTC2 encodes a 140kDa protein containing conserved SPX, VTC and transmembrane domains. TgVTC2 localizes in punctate spots within the cytoplasm that do not co-localize with known markers. The TgVTC2 mutant showed dramatically reduced polyphosphate accumulation, a defect restored by introduction of TgVTC2 to the mutant. Insertion within TgVTC2 resulted in increased transcript levels for two loci, including a putative FIKK kinase. These transcript levels were restored to wild-type levels upon complementation with the TgVTC2 locus. The TgVTC2 locus was refractory to knockout, and may be essential. Analysis of this TgVTC2 mutant will facilitate dissection of the T. gondii polyphosphate synthesis pathway.
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Affiliation(s)
- Peggy J Rooney
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Microbial Sciences Building Room 3345, 1550 Linden Drive, Madison, WI 53706, USA
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de Paulo Martins V, Okura M, Maric D, Engman DM, Vieira M, Docampo R, Moreno SNJ. Acylation-dependent export of Trypanosoma cruzi phosphoinositide-specific phospholipase C to the outer surface of amastigotes. J Biol Chem 2010; 285:30906-17. [PMID: 20647312 DOI: 10.1074/jbc.m110.142190] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphoinositide phospholipase C (PI-PLC) plays an essential role in cell signaling. A unique Trypanosoma cruzi PI-PLC (TcPI-PLC) is lipid-modified in its N terminus and localizes to the plasma membrane of amastigotes. Here, we show that TcPI-PLC is located onto the extracellular phase of the plasma membrane of amastigotes and that its N-terminal 20 amino acids are necessary and sufficient to target the fused GFP to the outer surface of the parasite. Mutagenesis of the predicted acylated residues confirmed that myristoylation of a glycine residue in the 2nd position and acyl modification of a cysteine in the 4th but not in the 8th or 15th position of the coding sequence are required for correct plasma membrane localization in T. cruzi epimastigotes or amastigotes. Interestingly, mutagenesis of the cysteine at the 8th position increased its flagellar localization. When expressed as fusion constructs with GFP, the N-terminal 6 and 10 amino acids fused to GFP are predominantly located in the cytosol and concentrated in a compartment that co-localizes with a Golgi complex marker. The N-terminal 20 amino acids of TcPI-PLC associate with lipid rafts when dually acylated. Taken together, these results indicate that N-terminal acyl modifications serve as a molecular addressing system for sending TcPI-PLC to the outer surface of the cell.
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Affiliation(s)
- Vicente de Paulo Martins
- Department of Cellular Biology, University of Georgia, Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602, USA
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46
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Docampo R, Ulrich P, Moreno SNJ. Evolution of acidocalcisomes and their role in polyphosphate storage and osmoregulation in eukaryotic microbes. Philos Trans R Soc Lond B Biol Sci 2010; 365:775-84. [PMID: 20124344 DOI: 10.1098/rstb.2009.0179] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acidocalcisomes are acidic electron-dense organelles, rich in polyphosphate (poly P) complexed with calcium and other cations. While its matrix contains enzymes related to poly P metabolism, the membrane of the acidocalcisomes has a number of pumps (Ca(2+)-ATPase, V-H(+)-ATPase, H(+)-PPase), exchangers (Na(+)/H(+), Ca(2+)/H(+)), and at least one channel (aquaporin). Acidocalcisomes are present in both prokaryotes and eukaryotes and are an important storage of cations and phosphorus. They also play an important role in osmoregulation and interact with the contractile vacuole complex in a number of eukaryotic microbes. Acidocalcisomes resemble lysosome-related organelles (LRO) from mammalian cells in many of their properties. They share similar morphological characteristics, acidic properties, phosphorus contents and a system for targeting of their membrane proteins through adaptor complex-3 (AP-3). Storage of phosphate and cations may represent the ancestral physiological function of acidocalcisomes, with cation and pH homeostasis and osmoregulatory functions derived following the divergence of prokaryotes and eukaryotes.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, GA 30602, USA.
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47
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Miranda K, Pace DA, Cintron R, Rodrigues JCF, Fang J, Smith A, Rohloff P, Coelho E, de Haas F, de Souza W, Coppens I, Sibley LD, Moreno SNJ. Characterization of a novel organelle in Toxoplasma gondii with similar composition and function to the plant vacuole. Mol Microbiol 2010; 76:1358-75. [PMID: 20398214 DOI: 10.1111/j.1365-2958.2010.07165.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. Like most apicomplexans, T. gondii possesses several plant-like features, such as the chloroplast-like organelle, the apicoplast. We describe and characterize a novel organelle in T. gondii tachyzoites, which is visible by light microscopy and possesses a broad similarity to the plant vacuole. Electron tomography shows the interaction of this vacuole with other organelles. The presence of a plant-like vacuolar proton pyrophosphatase (TgVP1), a vacuolar proton ATPase, a cathepsin L-like protease (TgCPL), an aquaporin (TgAQP1), as well as Ca(2+)/H(+) and Na(+)/H(+) exchange activities, supports similarity to the plant vacuole. Biochemical characterization of TgVP1 in enriched fractions shows a functional similarity to the respective plant enzyme. The organelle is a Ca(2+) store and appears to have protective effects against salt stress potentially linked to its sodium transport activity. In intracellular parasites, the organelle fragments, with some markers colocalizing with the late endosomal marker, Rab7, suggesting its involvement with the endocytic pathway. Studies on the characterization of this novel organelle will be relevant to the identification of novel targets for chemotherapy against T. gondii and other apicomplexan parasites as well.
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Affiliation(s)
- Kildare Miranda
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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48
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Abstract
Acidocalcisomes are acidic organelles with a high concentration of phosphorus present as pyrophosphate (PP(i)) and polyphosphate (poly P) complexed with calcium and other cations. The acidocalcisome membrane contains a number of pumps (Ca(2+)-ATPase, V-H(+)-ATPase, H(+)-PPase), exchangers (Na(+)/H(+), Ca(2+)/H(+)), and channels (aquaporins), while its matrix contains enzymes related to PP(i) and poly P metabolism. Acidocalcisomes have been observed in pathogenic, as well as non-pathogenic prokaryotes and eukaryotes, e.g. Chlamydomonas reinhardtii, and Dictyostelium discoideum. Some of the potential functions of the acidocalcisome are the storage of cations and phosphorus, the participation of phosphorus in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH homeostasis, and osmoregulation. In addition, acidocalcisomes resemble lysosome-related organelles (LRO) from mammalian cells in many of their properties. For example, we found that platelet dense granules, which are LROs, are very similar to acidocalcisomes. They share a similar size, acidic properties, and both contain PP(i), poly P, and calcium. Recent work that indicates that they also share the system for targeting of their membrane proteins through adaptor protein 3 reinforces this concept. The fact that acidocalcisomes interact with other organelles in parasitic protists, e.g. the contractile vacuole in Trypanosoma cruzi, and other vacuoles observed in Toxoplasma gondii, suggests that these cellular compartments may be associated with the endosomal/lysosomal pathway.
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Affiliation(s)
- Silvia N J Moreno
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, 30602, USA.
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49
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Abstract
BACKGROUND Isoprenoids are an extensive group of natural products with diverse structures consisting of various numbers of five carbon isopentenyl diphosphate (IPP) units. OBJECTIVE We review here what is known about the isoprenoid pathway in T. gondii. METHODS Recent primary literature is reviewed. RESULTS/CONCLUSION Genomic evidence points toward the presence of a 1-deoxy-D-xylulose 5-phosphate/2-C-methyl-D-erythritol 4-phosphate (DOXP/MEP) pathway, similar to the one found in plants, which will produce isopentenyl diphosphate (IPP). The DOXP/MEP pathway has been validated as a target in the related Apicomplexan parasite Plasmodium. The DOXP/MEP pathway in Toxoplasma has not been characterized. Downstream in the pathway, the enzyme farnesyl diphosphate synthase (FPPS) has a central role in forming important intermediates since farnesyl diphosphate (FPP) is a precursor of critical molecules with fundamental biological function such as dolichols, heme a, cholesterol, farnesylated proteins and others. Strong evidence indicates that this enzyme is a valid target for drugs since bisphosphonates, which are specific FPPS inhibitors, inhibited parasite growth in vitro and in vivo. Our hypothesis is that the isoprenoid pathway constitutes a major novel target for the treatment of toxoplasmosis.
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Affiliation(s)
- Silvia N J Moreno
- University of Georgia, Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, 500 D. W. Brooks Dr, Athens, Georgia 30602, USA.
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50
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Szajnman SH, García Liñares GE, Li ZH, Jiang C, Galizzi M, Bontempi EJ, Ferella M, Moreno SNJ, Docampo R, Rodriguez JB. Synthesis and biological evaluation of 2-alkylaminoethyl-1,1-bisphosphonic acids against Trypanosoma cruzi and Toxoplasma gondii targeting farnesyl diphosphate synthase. Bioorg Med Chem 2008; 16:3283-90. [PMID: 18096393 PMCID: PMC2330165 DOI: 10.1016/j.bmc.2007.12.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 12/05/2007] [Accepted: 12/06/2007] [Indexed: 11/28/2022]
Abstract
The effect of a series of 2-alkylaminoethyl-1,1-bisphosphonic acids against proliferation of the clinically more relevant form of Trypanosoma cruzi, the etiologic agent of American trypanosomiasis (Chagas' disease), and against tachyzoites of Toxoplasma gondii has been studied. Most of these drugs exhibited an extremely potent inhibitory action against the intracellular form of T. cruzi, exhibiting IC(50) values at the low micromolar level. This cellular activity was associated with a strong inhibition of the enzymatic activity of T. cruzi farnesyl diphosphate synthase (TcFPPS), which constitutes a valid target for Chagas' disease chemotherapy. Compound 17 was an effective agent against amastigotes exhibiting an IC(50) value of 0.84 microM, while this compound showed an IC(50) value of 0.49 microM against the target enzyme TcFPPS. Interestingly, compound 19 was very effective against both T. cruzi and T. gondii exhibiting IC(50) values of 4.1 microM and 2.6 microM, respectively. In this case, 19 inhibited at least two different enzymes of T. cruzi (TcFPPS and solanesyl diphosphate synthase (TcSPPS); 1.01 microM and 0.25 microM, respectively), while it inhibited TgFPPS in T. gondii. In general, this family of drugs was less effective against the activity of T. cruzi SPPS and against T. gondii growth in vitro. As bisphosphonate-containing compounds are FDA-approved drugs for the treatment of bone resorption disorders, their potential low toxicity makes them good candidates to control tropical diseases.
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Affiliation(s)
- Sergio H Szajnman
- Departamento de Química Orgánica and UMYMFOR (CONICET-FCEyN), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
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