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Ovciarikova J, Shikha S, Lacombe A, Courjol F, McCrone R, Hussain W, Maclean A, Lemgruber L, Martins-Duarte ES, Gissot M, Sheiner L. Two ancient membrane pores mediate mitochondrial-nucleus membrane contact sites. J Cell Biol 2024; 223:e202304075. [PMID: 38456969 PMCID: PMC10923651 DOI: 10.1083/jcb.202304075] [Citation(s) in RCA: 0] [Impact Index Per Article: 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] [Received: 04/22/2023] [Revised: 11/28/2023] [Accepted: 01/29/2024] [Indexed: 03/09/2024] Open
Abstract
Coordination between nucleus and mitochondria is essential for cell survival, and thus numerous communication routes have been established between these two organelles over eukaryotic cell evolution. One route for organelle communication is via membrane contact sites, functional appositions formed by molecular tethers. We describe a novel nuclear-mitochondrial membrane contact site in the protozoan Toxoplasma gondii. We have identified specific contacts occurring at the nuclear pore and demonstrated an interaction between components of the nuclear pore and the mitochondrial protein translocon, highlighting them as molecular tethers. Genetic disruption of the nuclear pore or the TOM translocon components, TgNup503 or TgTom40, respectively, result in contact site reduction, supporting their potential involvement in this tether. TgNup503 depletion further leads to specific mitochondrial morphology and functional defects, supporting a role for nuclear-mitochondrial contacts in mediating their communication. The discovery of a contact formed through interaction between two ancient mitochondrial and nuclear complexes sets the ground for better understanding of mitochondrial-nuclear crosstalk in eukaryotes.
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Affiliation(s)
- Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Shikha Shikha
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Alice Lacombe
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Flavie Courjol
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019—UMR 9017—CIIL—Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Rosalind McCrone
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Wasim Hussain
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Andrew Maclean
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Leandro Lemgruber
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Erica S. Martins-Duarte
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mathieu Gissot
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019—UMR 9017—CIIL—Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
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2
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Gui L, O'Shaughnessy WJ, Cai K, Reetz E, Reese ML, Nicastro D. Cryo-tomography reveals rigid-body motion and organization of apicomplexan invasion machinery. Nat Commun 2023; 14:1775. [PMID: 36997532 PMCID: PMC10063558 DOI: 10.1038/s41467-023-37327-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/10/2023] [Indexed: 04/03/2023] Open
Abstract
The apical complex is a specialized collection of cytoskeletal and secretory machinery in apicomplexan parasites, which include the pathogens that cause malaria and toxoplasmosis. Its structure and mechanism of motion are poorly understood. We used cryo-FIB-milling and cryo-electron tomography to visualize the 3D-structure of the apical complex in its protruded and retracted states. Averages of conoid-fibers revealed their polarity and unusual nine-protofilament arrangement with associated proteins connecting and likely stabilizing the fibers. Neither the structure of the conoid-fibers nor the architecture of the spiral-shaped conoid complex change during protrusion or retraction. Thus, the conoid moves as a rigid body, and is not spring-like and compressible, as previously suggested. Instead, the apical-polar-rings (APR), previously considered rigid, dilate during conoid protrusion. We identified actin-like filaments connecting the conoid and APR during protrusion, suggesting a role during conoid movements. Furthermore, our data capture the parasites in the act of secretion during conoid protrusion.
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Affiliation(s)
- Long Gui
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - William J O'Shaughnessy
- Department of Pharmacology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Kai Cai
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Evan Reetz
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Michael L Reese
- Department of Pharmacology, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
- Department of Biochemistry, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
| | - Daniela Nicastro
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
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3
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Dard C, Leforestier B, Francisco Hilário F, Traoré MDM, Lespinasse MA, Pérès B, Molina MC, Pereira de Freitas R, Milet A, Maubon D, Wong YS. Crossing of the Cystic Barriers of Toxoplasma gondii by the Fluorescent Coumarin Tetra-Cyclopeptide. Molecules 2021; 26:7506. [PMID: 34946588 PMCID: PMC8708940 DOI: 10.3390/molecules26247506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 11/10/2021] [Revised: 11/28/2021] [Accepted: 12/05/2021] [Indexed: 01/11/2023] Open
Abstract
FR235222 is a natural tetra-cyclopeptide with a strong inhibition effect on histone deacetylases, effective on mammalian cells as well as on intracellular apicomplexan parasites, such as Toxoplasma gondii, in the tachyzoite and bradyzoite stages. This molecule is characterized by two parts: the zinc-binding group, responsible for the binding to the histone deacetylase, and the cyclic tetrapeptide moiety, which plays a crucial role in cell permeability. Recently, we have shown that the cyclic tetrapeptide coupled with a fluorescent diethyl-amino-coumarin was able to maintain properties of cellular penetration on human cells. Here, we show that this property can be extended to the crossing of the Toxoplasma gondii cystic cell wall and the cell membrane of the parasite in its bradyzoite form, while maintaining a high efficacy as a histone deacetylase inhibitor. The investigation by molecular modeling allows a better understanding of the penetration mechanism.
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Affiliation(s)
- Céline Dard
- Team Host-Pathogen Interactions and Immunity to Infection, Institute for Advanced Biosciences, INSERM, CNRSINSERM U1209, CNRS UMR 5309, Univ. Grenoble Alpes, 38000 Grenoble, France; (C.D.); (D.M.)
| | - Baptiste Leforestier
- Team SITH, CNRS UMR 5250, Univ. Grenoble Alpes, CNRS, DCM, 38000 Grenoble, France; (B.L.); (A.M.)
| | - Flaviane Francisco Hilário
- Team COMET, CNRS UMR 5063, Univ. Grenoble Alpes, CNRS, DPM, 38000 Grenoble, France; (F.F.H.); (M.D.M.T.); (M.-A.L.); (B.P.); (M.-C.M.)
| | - Mohamed Dit Mady Traoré
- Team COMET, CNRS UMR 5063, Univ. Grenoble Alpes, CNRS, DPM, 38000 Grenoble, France; (F.F.H.); (M.D.M.T.); (M.-A.L.); (B.P.); (M.-C.M.)
| | - Marie-Ange Lespinasse
- Team COMET, CNRS UMR 5063, Univ. Grenoble Alpes, CNRS, DPM, 38000 Grenoble, France; (F.F.H.); (M.D.M.T.); (M.-A.L.); (B.P.); (M.-C.M.)
| | - Basile Pérès
- Team COMET, CNRS UMR 5063, Univ. Grenoble Alpes, CNRS, DPM, 38000 Grenoble, France; (F.F.H.); (M.D.M.T.); (M.-A.L.); (B.P.); (M.-C.M.)
| | - Marie-Carmen Molina
- Team COMET, CNRS UMR 5063, Univ. Grenoble Alpes, CNRS, DPM, 38000 Grenoble, France; (F.F.H.); (M.D.M.T.); (M.-A.L.); (B.P.); (M.-C.M.)
| | - Rossimiriam Pereira de Freitas
- Departamento de Química, Universidade Federal de Minas Gerais, Av Pres Antônio Carlos, 6627, Pampulha, Belo Horizonte 31270-901, MG, Brazil;
| | - Anne Milet
- Team SITH, CNRS UMR 5250, Univ. Grenoble Alpes, CNRS, DCM, 38000 Grenoble, France; (B.L.); (A.M.)
| | - Danièle Maubon
- Team Host-Pathogen Interactions and Immunity to Infection, Institute for Advanced Biosciences, INSERM, CNRSINSERM U1209, CNRS UMR 5309, Univ. Grenoble Alpes, 38000 Grenoble, France; (C.D.); (D.M.)
| | - Yung-Sing Wong
- Departamento de Química, Universidade Federal de Minas Gerais, Av Pres Antônio Carlos, 6627, Pampulha, Belo Horizonte 31270-901, MG, Brazil;
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4
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Quiarim TM, Maia MM, da Cruz AB, Taniwaki NN, Namiyama GM, Pereira-Chioccola VL. Characterization of extracellular vesicles isolated from types I, II and III strains of Toxoplasma gondii. Acta Trop 2021; 219:105915. [PMID: 33861971 DOI: 10.1016/j.actatropica.2021.105915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/15/2021] [Accepted: 03/27/2021] [Indexed: 12/31/2022]
Abstract
This study investigated the participation extracellular vesicles (EVs) in Toxoplasma gondii-host interaction. EVs of three T. gondii strains (RH, ME-49 and VEG) were purified by chromatography and ELISA. Results of "nanoparticle tracking analysis" and scanning electron microscopy showed that RH strain released more EVs than other strains. Images of transmission electron microscopy showed that in beginning of incubation (culture medium), EVs were inside of tachyzoites preparing to be released. After 24 hours, they were largely produced inside tachyzoites and were released through plasma membrane. The parasite burden of mice infected with RH strain plus EVs was increased and with early death of 1-2 days compared of those that received only parasites. EV proteins of ME-49 and VEG strains were poorly reactive to sera of infected patients in imunoblot. However, those from RH strain were reactive against sera of patients with cerebral toxoplasmosis. EVs stimulated murine splenocytes caused similar production of IFN-γ and IL-10 levels. RH strain derived EVs stimulated more TNF-α than those stimulated by other strains. T. gondii and infected hosts can express the same miRNAs (miR-155-5p, miR-125b-5p, miR-423-3p). In conclusion, T. gondii derived EVs promote host-parasite interactions, modulate host immune responses, carry virulent factors and cause an imbalance in cellular immune response.
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Affiliation(s)
- Talita Motta Quiarim
- Laboratório de Biologia Molecular de Parasitas e Fungos, Instituto Adolfo Lutz, Sao Paulo, Brazil.
| | - Marta Marques Maia
- Laboratório de Biologia Molecular de Parasitas e Fungos, Instituto Adolfo Lutz, Sao Paulo, Brazil.
| | - Allecineia Bispo da Cruz
- Laboratório de Biologia Molecular de Parasitas e Fungos, Instituto Adolfo Lutz, Sao Paulo, Brazil.
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5
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Jacobs K, Charvat R, Arrizabalaga G. Identification of Fis1 Interactors in Toxoplasma gondii Reveals a Novel Protein Required for Peripheral Distribution of the Mitochondrion. mBio 2020; 11:e02732-19. [PMID: 32047127 PMCID: PMC7018656 DOI: 10.1128/mbio.02732-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [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: 10/12/2019] [Accepted: 12/23/2019] [Indexed: 12/26/2022] Open
Abstract
Toxoplasma gondii's single mitochondrion is very dynamic and undergoes morphological changes throughout the parasite's life cycle. During parasite division, the mitochondrion elongates, enters the daughter cells just prior to cytokinesis, and undergoes fission. Extensive morphological changes also occur as the parasite transitions from the intracellular environment to the extracellular environment. We show that treatment with the ionophore monensin causes reversible constriction of the mitochondrial outer membrane and that this effect depends on the function of the fission-related protein Fis1. We also observed that mislocalization of the endogenous Fis1 causes a dominant-negative effect that affects the morphology of the mitochondrion. As this suggests that Fis1 interacts with proteins critical for maintenance of mitochondrial structure, we performed various protein interaction trap screens. In this manner, we identified a novel outer mitochondrial membrane protein, LMF1, which is essential for positioning of the mitochondrion in intracellular parasites. Normally, while inside a host cell, the parasite mitochondrion is maintained in a lasso shape that stretches around the parasite periphery where it has regions of coupling with the parasite pellicle, suggesting the presence of membrane contact sites. In intracellular parasites lacking LMF1, the mitochondrion is retracted away from the pellicle and instead is collapsed, as normally seen only in extracellular parasites. We show that this phenotype is associated with defects in parasite fitness and mitochondrial segregation. Thus, LMF1 is necessary for mitochondrial association with the parasite pellicle during intracellular growth, and proper mitochondrial morphology is a prerequisite for mitochondrial division.IMPORTANCEToxoplasma gondii is an opportunistic pathogen that can cause devastating tissue damage in the immunocompromised and congenitally infected. Current therapies are not effective against all life stages of the parasite, and many cause toxic effects. The single mitochondrion of this parasite is a validated drug target, and it changes its shape throughout its life cycle. When the parasite is inside a cell, the mitochondrion adopts a lasso shape that lies in close proximity to the pellicle. The functional significance of this morphology is not understood and the proteins involved are currently not known. We have identified a protein that is required for proper mitochondrial positioning at the periphery and that likely plays a role in tethering this organelle. Loss of this protein results in dramatic changes to the mitochondrial morphology and significant parasite division and propagation defects. Our results give important insight into the molecular mechanisms regulating mitochondrial morphology.
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Affiliation(s)
- Kylie Jacobs
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Robert Charvat
- Department of Biology, University of Findlay, Findlay, Ohio, USA
| | - Gustavo Arrizabalaga
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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6
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Abstract
O-Glycosylation is an increasingly recognized modification of intracellular proteins in all kingdoms of life, and its occurrence in protists has been investigated to understand its evolution and its roles in the virulence of unicellular pathogens. We focus here on two kinds of glycoregulation found in unicellular eukaryotes: one is a simple O-fucose modification of dozens if not hundreds of Ser/Thr-rich proteins, and the other a complex pentasaccharide devoted to a single protein associated with oxygen sensing and the assembly of polyubiquitin chains. These modifications are not required for life but contingently modulate biological processes in the social amoeba Dictyostelium and the human pathogen Toxoplasma gondii, and likely occur in diverse unicellular protists. O-Glycosylation that is co-localized in the cytoplasm allows for glycoregulation over the entire life of the protein, contrary to the secretory pathway where glycosylation usually occurs before its delivery to its site of function. Here, we interpret cellular roles of nucleocytoplasmic glycans in terms of current evidence for their effects on the conformation and dynamics of protist proteins, to serve as a guide for future studies to examine their broader significance.
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Affiliation(s)
- Christopher M West
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602 USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602 USA; Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA.
| | - Hyun W Kim
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602 USA
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7
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Biddau M, Bouchut A, Major J, Saveria T, Tottey J, Oka O, van-Lith M, Jennings KE, Ovciarikova J, DeRocher A, Striepen B, Waller RF, Parsons M, Sheiner L. Two essential Thioredoxins mediate apicoplast biogenesis, protein import, and gene expression in Toxoplasma gondii. PLoS Pathog 2018; 14:e1006836. [PMID: 29470517 PMCID: PMC5823475 DOI: 10.1371/journal.ppat.1006836] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [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: 09/08/2017] [Accepted: 12/21/2017] [Indexed: 11/19/2022] Open
Abstract
Apicomplexan parasites are global killers, being the causative agents of diseases like toxoplasmosis and malaria. These parasites are known to be hypersensitive to redox imbalance, yet little is understood about the cellular roles of their various redox regulators. The apicoplast, an essential plastid organelle, is a verified apicomplexan drug target. Nuclear-encoded apicoplast proteins traffic through the ER and multiple apicoplast sub-compartments to their place of function. We propose that thioredoxins contribute to the control of protein trafficking and of protein function within these apicoplast compartments. We studied the role of two Toxoplasma gondiiapicoplast thioredoxins (TgATrx), both essential for parasite survival. By describing the cellular phenotypes of the conditional depletion of either of these redox regulated enzymes we show that each of them contributes to a different apicoplast biogenesis pathway. We provide evidence for TgATrx1’s involvement in ER to apicoplast trafficking and TgATrx2 in the control of apicoplast gene expression components. Substrate pull-down further recognizes gene expression factors that interact with TgATrx2. We use genetic complementation to demonstrate that the function of both TgATrxs is dependent on their disulphide exchange activity. Finally, TgATrx2 is divergent from human thioredoxins. We demonstrate its activity in vitro thus providing scope for drug screening. Our study represents the first functional characterization of thioredoxins in Toxoplasma, highlights the importance of redox regulation of apicoplast functions and provides new tools to study redox biology in these parasites. To survive, apicomplexan parasites must adjust to the redox insults they experience. These parasites undergo redox stresses induced by the host cell within which they live, by the host immune system, and by their own metabolic activities. Yet the myriad of cellular processes that are affected by redox changes and that may take part in maintaining the redox balance within the parasite are largely understudied. Thioredoxins are enzymes that link the redox state of subcellular environments to the functional state or the cellular trafficking of their substrate proteins. In this work, we identify two pathways that are controlled by two thioredoxins in the apicomplexan Toxoplasma gondii, and demonstrate that both are essential for parasite survival. We show that each of these enzymes contributes to the function of the apicomplexan plastid, the apicoplast, a unique parasite organelle with importance for drug discovery efforts. We thus highlight that part of the apicomplexan sensitivity to redox imbalance is specifically related to the apicoplast, and point at the importance of thioredoxins in mediating apicoplast biogenesis. Finally, our work raises the potential of apicoplast thioredoxins as new drug targets.
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Affiliation(s)
- Marco Biddau
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Anne Bouchut
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Jack Major
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Tracy Saveria
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Julie Tottey
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Ojore Oka
- Institute of Molecular Cell and Systems Biology, Wolfson Link Building, University of Glasgow, Glasgow, United Kingdom
| | - Marcel van-Lith
- Institute of Molecular Cell and Systems Biology, Wolfson Link Building, University of Glasgow, Glasgow, United Kingdom
| | - Katherine Elizabeth Jennings
- Center for Tropical & Emerging Global Diseases, University of Georgia, Brooks Dr. Athens, GA, United States of America
| | - Jana Ovciarikova
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Amy DeRocher
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Boris Striepen
- Center for Tropical & Emerging Global Diseases, University of Georgia, Brooks Dr. Athens, GA, United States of America
| | | | - Marilyn Parsons
- Center for Infectious Disease Research, Seattle, WA, United States of America
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Lilach Sheiner
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
- * E-mail:
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8
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Alvarez CA, Suvorova ES. Checkpoints of apicomplexan cell division identified in Toxoplasma gondii. PLoS Pathog 2017; 13:e1006483. [PMID: 28671988 PMCID: PMC5510908 DOI: 10.1371/journal.ppat.1006483] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [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: 02/10/2017] [Revised: 07/14/2017] [Accepted: 06/20/2017] [Indexed: 11/18/2022] Open
Abstract
The unusual cell cycles of Apicomplexa parasites are remarkably flexible with the ability to complete cytokinesis and karyokinesis coordinately or postpone cytokinesis for several rounds of chromosome replication, and are well recognized. Despite this surprising biology, the molecular machinery required to achieve this flexibility is largely unknown. In this study, we provide comprehensive experimental evidence that apicomplexan parasites utilize multiple Cdk-related kinases (Crks) to coordinate cell division. We determined that Toxoplasma gondii encodes seven atypical P-, H-, Y- and L- type cyclins and ten Crks to regulate cellular processes. We generated and analyzed conditional tet-OFF mutants for seven TgCrks and four TgCyclins that are expressed in the tachyzoite stage. These experiments demonstrated that TgCrk1, TgCrk2, TgCrk4 and TgCrk6, were required or essential for tachyzoite growth revealing a remarkable number of Crk factors that are necessary for parasite replication. G1 phase arrest resulted from the loss of cytoplasmic TgCrk2 that interacted with a P-type cyclin demonstrating that an atypical mechanism controls half the T. gondii cell cycle. We showed that T. gondii employs at least three TgCrks to complete mitosis. Novel kinases, TgCrk6 and TgCrk4 were required for spindle function and centrosome duplication, respectively, while TgCrk1 and its partner TgCycL were essential for daughter bud assembly. Intriguingly, mitotic kinases TgCrk4 and TgCrk6 did not interact with any cyclin tested and were instead dynamically expressed during mitosis indicating they may not require a cyclin timing mechanism. Altogether, our findings demonstrate that apicomplexan parasites utilize distinctive and complex mechanisms to coordinate their novel replicative cycles. Apicomplexan parasites are unicellular eukaryotes that replicate in unusual ways different from their multicellular hosts. From a single infection, different apicomplexans can produce as few as two or up to many hundreds of progeny. How these flexible division cycles are regulated is poorly understood. In the current study we have defined the major mechanisms controlling the growth of the Toxoplasma gondii acute pathogenic stage called the tachyzoite. We show that T. gondii tachyzoites require not only multiple protein kinases to coordinate chromosome replication and the assembly of new daughter parasites, but also each kinase has unique responsibilities. By contrast, the mammalian cell that T. gondii infects requires far fewer kinase regulators to complete cell division, which suggests that these parasites have unique vulnerabilities. The increased complexity in parasite cell cycle controls likely evolved from the need to adapt to different hosts and the need to construct the specialized invasion apparatus in order to invade those hosts.
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Affiliation(s)
- Carmelo A. Alvarez
- Department of Global Health and the Florida Center for Drug Discovery and Innovation, University of South Florida, Tampa, Florida, United States of America
| | - Elena S. Suvorova
- Department of Global Health and the Florida Center for Drug Discovery and Innovation, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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9
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Jacot D, Tosetti N, Pires I, Stock J, Graindorge A, Hung YF, Han H, Tewari R, Kursula I, Soldati-Favre D. An Apicomplexan Actin-Binding Protein Serves as a Connector and Lipid Sensor to Coordinate Motility and Invasion. Cell Host Microbe 2016; 20:731-743. [PMID: 27978434 DOI: 10.1016/j.chom.2016.10.020] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [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: 06/27/2016] [Revised: 09/16/2016] [Accepted: 10/27/2016] [Indexed: 01/06/2023]
Abstract
Apicomplexa exhibit a unique form of substrate-dependent gliding motility central for host cell invasion and parasite dissemination. Gliding is powered by rearward translocation of apically secreted transmembrane adhesins via their interaction with the parasite actomyosin system. We report a conserved armadillo and pleckstrin homology (PH) domain-containing protein, termed glideosome-associated connector (GAC), that mediates apicomplexan gliding motility, invasion, and egress by connecting the micronemal adhesins with the actomyosin system. TgGAC binds to and stabilizes filamentous actin and specifically associates with the transmembrane adhesin TgMIC2. GAC localizes to the apical pole in invasive stages of Toxoplasma gondii and Plasmodium berghei, and apical positioning of TgGAC depends on an apical lysine methyltransferase, TgAKMT. GAC PH domain also binds to phosphatidic acid, a lipid mediator associated with microneme exocytosis. Collectively, these findings indicate a central role for GAC in spatially and temporally coordinating gliding motility and invasion.
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Affiliation(s)
- Damien Jacot
- Department of Microbiology & Molecular Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva, Switzerland
| | - Nicolò Tosetti
- Department of Microbiology & Molecular Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva, Switzerland
| | - Isa Pires
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Jessica Stock
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG2 7UH, UK
| | - Arnault Graindorge
- Department of Microbiology & Molecular Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva, Switzerland
| | - Yu-Fu Hung
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Huijong Han
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Rita Tewari
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG2 7UH, UK
| | - Inari Kursula
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland; Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway.
| | - Dominique Soldati-Favre
- Department of Microbiology & Molecular Medicine, University of Geneva, 1 Rue Michel-Servet, 1211 Geneva, Switzerland.
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Foe IT, Child MA, Majmudar JD, Krishnamurthy S, van der Linden WA, Ward GE, Martin BR, Bogyo M. Global Analysis of Palmitoylated Proteins in Toxoplasma gondii. Cell Host Microbe 2016; 18:501-11. [PMID: 26468752 DOI: 10.1016/j.chom.2015.09.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [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: 06/17/2015] [Revised: 08/25/2015] [Accepted: 09/16/2015] [Indexed: 02/01/2023]
Abstract
Post-translational modifications (PTMs) such as palmitoylation are critical for the lytic cycle of the protozoan parasite Toxoplasma gondii. While palmitoylation is involved in invasion, motility, and cell morphology, the proteins that utilize this PTM remain largely unknown. Using a chemical proteomic approach, we report a comprehensive analysis of palmitoylated proteins in T. gondii, identifying a total of 282 proteins, including cytosolic, membrane-associated, and transmembrane proteins. From this large set of palmitoylated targets, we validate palmitoylation of proteins involved in motility (myosin light chain 1, myosin A), cell morphology (PhIL1), and host cell invasion (apical membrane antigen 1, AMA1). Further studies reveal that blocking AMA1 palmitoylation enhances the release of AMA1 and other invasion-related proteins from apical secretory organelles, suggesting a previously unrecognized role for AMA1. These findings suggest that palmitoylation is ubiquitous throughout the T. gondii proteome and reveal insights into the biology of this important human pathogen.
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Affiliation(s)
- Ian T Foe
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Matthew A Child
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jaimeen D Majmudar
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shruthi Krishnamurthy
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | | | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Brent R Martin
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Matthew Bogyo
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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11
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Dubey JP, Ferreira LR, Alsaad M, Verma SK, Alves DA, Holland GN, McConkey GA. Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions. PLoS One 2016; 11:e0156255. [PMID: 27228262 PMCID: PMC4882154 DOI: 10.1371/journal.pone.0156255] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/26/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse. METHODOLOGY/PRINCIPAL FINDINGS Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains) of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection) of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i.) to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25%) of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg muscle. CONCLUSION/SIGNIFICANCE This study reevaluated in depth the rat model of toxoplasmosis visualizing cyst rupture and clarified many aspects of the biology of the parasite useful for future investigations.
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Affiliation(s)
- Jitender P. Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland, United States of America
| | - Leandra R. Ferreira
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland, United States of America
| | - Mohammad Alsaad
- Faculty of Biological Sciences, University of Leeds, Miall Building, Clarendon Way, Leeds, United Kingdom
| | - Shiv K. Verma
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland, United States of America
| | - Derron A. Alves
- Veterinary Pathology Services Joint Pathology Center, 606 Stephen Sitter Ave. Silver Spring, Maryland, United States of America
| | - Gary N. Holland
- Ocular Inflammatory Disease Center, University of California at Los Angles Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Glenn A. McConkey
- Faculty of Biological Sciences, University of Leeds, Miall Building, Clarendon Way, Leeds, United Kingdom
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12
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Wang K, Peng ED, Huang AS, Xia D, Vermont SJ, Lentini G, Lebrun M, Wastling JM, Bradley PJ. Identification of Novel O-Linked Glycosylated Toxoplasma Proteins by Vicia villosa Lectin Chromatography. PLoS One 2016; 11:e0150561. [PMID: 26950937 PMCID: PMC4780768 DOI: 10.1371/journal.pone.0150561] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [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: 06/16/2015] [Accepted: 02/15/2016] [Indexed: 12/31/2022] Open
Abstract
Toxoplasma gondii maintains its intracellular life cycle using an extraordinary arsenal of parasite-specific organelles including the inner membrane complex (IMC), rhoptries, micronemes, and dense granules. While these unique compartments play critical roles in pathogenesis, many of their protein constituents have yet to be identified. We exploited the Vicia villosa lectin (VVL) to identify new glycosylated proteins that are present in these organelles. Purification of VVL-binding proteins by lectin affinity chromatography yielded a number of novel proteins that were subjected to further study, resulting in the identification of proteins from the dense granules, micronemes, rhoptries and IMC. We then chose to focus on three proteins identified by this approach, the SAG1 repeat containing protein SRS44, the rhoptry neck protein RON11 as well as a novel IMC protein we named IMC25. To assess function, we disrupted their genes by homologous recombination or CRISPR/Cas9. The knockouts were all successful, demonstrating that these proteins are not essential for invasion or intracellular survival. We also show that IMC25 undergoes substantial proteolytic processing that separates the C-terminal domain from the predicted glycosylation site. Together, we have demonstrated that lectin affinity chromatography is an efficient method of identifying new glycosylated parasite-specific proteins.
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Affiliation(s)
- Kevin Wang
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, 90095–1489, United States of America
| | - Eric D. Peng
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, 90095–1489, United States of America
| | - Amy S. Huang
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, 90095–1489, United States of America
| | - Dong Xia
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Sarah J. Vermont
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Gaelle Lentini
- UMR 5235 CNRS, Université de Montpellier 1 and 2, 34095, Montpellier, France
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier 1 and 2, 34095, Montpellier, France
| | | | - Peter J. Bradley
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, 90095–1489, United States of America
- * E-mail:
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13
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Graindorge A, Frénal K, Jacot D, Salamun J, Marq JB, Soldati-Favre D. The Conoid Associated Motor MyoH Is Indispensable for Toxoplasma gondii Entry and Exit from Host Cells. PLoS Pathog 2016; 12:e1005388. [PMID: 26760042 PMCID: PMC4711953 DOI: 10.1371/journal.ppat.1005388] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/17/2015] [Indexed: 11/23/2022] Open
Abstract
Many members of the phylum of Apicomplexa have adopted an obligate intracellular life style and critically depend on active invasion and egress from the infected cells to complete their lytic cycle. Toxoplasma gondii belongs to the coccidian subgroup of the Apicomplexa, and as such, the invasive tachyzoite contains an organelle termed the conoid at its extreme apex. This motile organelle consists of a unique polymer of tubulin fibres and protrudes in both gliding and invading parasites. The class XIV myosin A, which is conserved across the Apicomplexa phylum, is known to critically contribute to motility, invasion and egress from infected cells. The MyoA-glideosome is anchored to the inner membrane complex (IMC) and is assumed to translocate the components of the circular junction secreted by the micronemes and rhoptries, to the rear of the parasite. Here we comprehensively characterise the class XIV myosin H (MyoH) and its associated light chains. We show that the 3 alpha-tubulin suppressor domains, located in MyoH tail, are necessary to anchor this motor to the conoid. Despite the presence of an intact MyoA-glideosome, conditional disruption of TgMyoH severely compromises parasite motility, invasion and egress from infected cells. We demonstrate that MyoH is necessary for the translocation of the circular junction from the tip of the parasite, where secretory organelles exocytosis occurs, to the apical position where the IMC starts. This study attributes for the first time a direct function of the conoid in motility and invasion, and establishes the indispensable role of MyoH in initiating the first step of motility along this unique organelle, which is subsequently relayed by MyoA to enact effective gliding and invasion. The Apicomplexa phylum groups important pathogens that infect humans and animals. Host cell invasion and egress from infected cells are key events in the lytic cycle of these obligate intracellular parasites. Host cell entry is powered by gliding motility and initiated by the discharge of apical secretory organelles at the site of contact with the host cell. Anchored to the parasite pellicle, the glideosome composed of myosin A and the gliding associated proteins is the molecular machine which translocates the secreted adhesins from the apical to the posterior pole of the parasite and hence propels the parasite into the host cell. Toxoplasma gondii exhibits a helical form of gliding motility and as member of the coccidian-subgroup of Apicomplexa possesses an apical organelle called the conoid, which protrudes during invasion and egress and consists in helically organized polymer of tubulin fibers. We have deciphered here the function of a novel myosin associated to the microtubules composing the conoid. Myosin H is essential and prerequisite for motility, invasion and egress from infected cells. This unusual motor links actin- and tubulin-based cytoskeletons and uncovers a direct role of the conoid in motility and invasion.
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Affiliation(s)
- Arnault Graindorge
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Karine Frénal
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Damien Jacot
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Julien Salamun
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Jean Baptiste Marq
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- * E-mail:
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14
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Abstract
Micronemal protein 2 (MIC2) is the key adhesin that supports gliding motility and host cell invasion by Toxoplasma gondii. With a von Willebrand factor A (VWA) domain and six thrombospondin repeat domains (TSR1-6) in its ectodomain, MIC2 connects to the parasite actomyosin system through its cytoplasmic tail. MIC2-associated protein (M2AP) binds noncovalently to the MIC2 ectodomain. MIC2 and M2AP are stored in micronemes as proforms. We find that the MIC2-M2AP ectodomain complex is a highly elongated 1:1 monomer with M2AP bound to the TSR6 domain. Crystal structures of N-terminal fragments containing the VWA and TSR1 domains for proMIC2 and MIC2 reveal a closed conformation of the VWA domain and how it associates with the TSR1 domain. A long, proline-rich, disulfide-bonded pigtail loop in TSR1 overlaps the VWA domain. Mannose α-C-linked to Trp-276 in TSR1 has an unusual (1)C4 chair conformation. The MIC2 VWA domain includes a mobile α5-helix and a 22-residue disordered region containing two disulfide bonds in place of an α6-helix. A hydrophobic residue in the prodomain binds to a pocket adjacent to the α7-helix that pistons in opening of the VWA domain to a putative high-affinity state.
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Affiliation(s)
- Gaojie Song
- Program in Cellular and Molecular Medicine and Division of Hematology, Department of Medicine, Boston Children's Hospital, Boston, MA 02115; and
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Timothy A. Springer
- Program in Cellular and Molecular Medicine and Division of Hematology, Department of Medicine, Boston Children's Hospital, Boston, MA 02115; and
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
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15
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Zhou W, Quan JH, Lee YH, Shin DW, Cha GH. Toxoplasma gondii Proliferation Require Down-Regulation of Host Nox4 Expression via Activation of PI3 Kinase/Akt Signaling Pathway. PLoS One 2013; 8:e66306. [PMID: 23824914 PMCID: PMC3688893 DOI: 10.1371/journal.pone.0066306] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 05/03/2013] [Indexed: 01/22/2023] Open
Abstract
Toxoplasma gondii results in ocular toxoplasmosis characterized by chorioretinitis with inflammation and necrosis of the neuroretina, pigment epithelium, and choroid. After invasion, T. gondii replicates in host cells before cell lysis, which releases the parasites to invade neighboring cells to repeat the life cycle and establish a chronic retinal infection. The mechanism by which T. gondii avoids innate immune defense, however, is unknown. Therefore, we determined whether PI3K/Akt signaling pathway activation by T. gondii is essential for subversion of host immunity and parasite proliferation. T. gondii infection or excretory/secretory protein (ESP) treatment of the human retinal pigment epithelium cell line ARPE-19 induced Akt phosphorylation, and PI3K inhibitors effectively reduced T. gondii proliferation in host cells. Furthermore, T. gondii reduced intracellular reactive oxygen species (ROS) while activating the PI3K/Akt signaling pathway. While searching for the main source of these ROS, we found that NADPH oxidase 4 (Nox4) was prominently expressed in ARPE-19 cells, and this expression was significantly reduced by T. gondii infection or ESP treatment along with decreased ROS levels. In addition, artificial reduction of host Nox4 levels with specific siRNA increased replication of intracellular T. gondii compared to controls. Interestingly, these T. gondii-induced effects were reversed by PI3K inhibitors, suggesting that activation of the PI3K/Akt signaling pathway is important for suppression of both Nox4 expression and ROS levels by T. gondii infection. These findings demonstrate that manipulation of the host PI3K/Akt signaling pathway and Nox4 gene expression is a novel mechanism involved in T. gondii survival and proliferation.
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Affiliation(s)
- Wei Zhou
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon, Korea
| | - Juan-Hua Quan
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon, Korea
- Department of Gastroenterology, The Affiliated Hospital of Guangdong Medical College, Zhanjiang, Guangdong, China
| | - Young-Ha Lee
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon, Korea
| | - Dae-Whan Shin
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon, Korea
| | - Guang-Ho Cha
- Department of Infection Biology, Chungnam National University School of Medicine, Daejeon, Korea
- * E-mail:
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16
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Lavine MD, Arrizabalaga G. Analysis of monensin sensitivity in Toxoplasma gondii reveals autophagy as a mechanism for drug induced death. PLoS One 2012; 7:e42107. [PMID: 22848721 PMCID: PMC3405052 DOI: 10.1371/journal.pone.0042107] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [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: 05/22/2012] [Accepted: 07/02/2012] [Indexed: 11/18/2022] Open
Abstract
Understanding the mechanisms by which anti-parasitic drugs alter the physiology and ultimately kill is an important area of investigation. Development of novel parasitic drugs, as well as the continued utilization of existing drugs in the face of resistant parasite populations, requires such knowledge. Here we show that the anti-coccidial drug monensin kills Toxoplasma gondii by inducing autophagy in the parasites, a novel mechanism of cell death in response to an antimicrobial drug. Monensin treatment results autophagy, as shown by translocation of ATG8 to autophagosomes, as well as causing marked morphological changes in the parasites' mitochondria. Use of the autophagy inhibitor 3-methyladenine blocks autophagy and mitochondrial alterations, and enhances parasite survival, in monensin-exposed parasites, although it does not block other monensin-induced effects on the parasites, such as late S-phase cell cycle arrest. Monensin does not induce autophagy in a parasite strain deficient in the mitochondrial DNA repair enzyme TgMSH-1 an enzyme that mediates monensin-induced late S-phase arrest. TgMSH-1 therefore either mediates cell cycle arrest and autophagy independently, or autophagy occurs downstream of cell cycle arrest in a manner analogous to apoptosis of cells arrested in G2 of the cell cycle. Overall, our results point to autophagy as a potentially important mode of cell death of protozoan parasites in response to antimicrobial drugs and indicate that disruption of the autophagy pathway could result in drug resistance.
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Affiliation(s)
- Mark D. Lavine
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Gustavo Arrizabalaga
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- * E-mail:
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17
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Gong H, Kobayashi K, Sugi T, Takemae H, Kurokawa H, Horimoto T, Akashi H, Kato K. A novel PAN/apple domain-containing protein from Toxoplasma gondii: characterization and receptor identification. PLoS One 2012; 7:e30169. [PMID: 22276154 PMCID: PMC3261864 DOI: 10.1371/journal.pone.0030169] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 12/14/2011] [Indexed: 12/03/2022] Open
Abstract
Toxoplasma gondii is an intracellular parasite that invades nucleated cells, causing toxoplasmosis in humans and animals worldwide. The extremely wide range of hosts susceptible to T. gondii is thought to be the result of interactions between T. gondii ligands and receptors on its target cells. In this study, a host cell-binding protein from T. gondii was characterized, and one of its receptors was identified. P104 (GenBank Access. No. CAJ20677) is 991 amino acids in length, containing a putative 26 amino acid signal peptide and 10 PAN/apple domains, and shows low homology to other identified PAN/apple domain-containing molecules. A 104-kDa host cell-binding protein was detected in the T. gondii lysate. Immunofluorescence assays detected P104 at the apical end of extracellular T. gondii. An Fc-fusion protein of the P104 N-terminus, which contains two PAN/apple domains, showed strong affinity for the mammalian and insect cells evaluated. This binding was not related to protein-protein or protein-lipid interactions, but to a protein-glycosaminoglycan (GAG) interaction. Chondroitin sulfate (CS), a kind of GAG, was shown to be involved in adhesion of the Fc-P104 N-terminus fusion protein to host cells. These results suggest that P104, expressed at the apical end of the extracellular parasite, may function as a ligand in the attachment of T. gondii to CS or other receptors on the host cell, facilitating invasion by the parasite.
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Affiliation(s)
- Haiyan Gong
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Kyousuke Kobayashi
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Tatsuki Sugi
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Hitoshi Takemae
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Hitomi Kurokawa
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Taisuke Horimoto
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Hiroomi Akashi
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Kentaro Kato
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan
- * E-mail:
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18
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Bártová E, Dvoráková H, Bárta J, Sedlák K, Literák I. Susceptibility of the domestic duck (Anas platyrhynchos) to experimental infection with Toxoplasma gondii oocysts. Avian Pathol 2010; 33:153-7. [PMID: 15276981 DOI: 10.1080/03079450310001652068] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A total of 28 domestic ducks were divided into seven groups of four ducks. Six groups were inoculated per os with 10(1), 10(2), 10(3), 10(4), 10(5) and 10(5.7) oocysts Toxoplasma gondii oocysts (K21 strain, which is avirulent for mice), and the remaining group was used as a control. Antibodies to T. gondii were detected in all ducks by the indirect fluorescence antibody test first on day 7 post-inoculation (p.i.). Antibody titres were found in the range of 1:20 to 1:640 depending on the infectious dose of the oocysts. From day 14 p.i. antibody titres increased to 1:80 to 1:20 480. Between days 14 and 28 p.i. (end of the experiment), antibody titres decreased in 14 ducks, remained the same in seven ducks, and continued to increase in three ducks. Bioassay in mice revealed T. gondii in the breast and leg muscles and the heart (100%, n=47), brain (91%, n=22), liver (54%, n=13) and stomach (46%, n=24). The infected ducks showed no clinical signs; however, the results of bioassay indicate that, compared with some gallinaceous birds, domestic ducks were relatively susceptible to T. gondii infection.
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Affiliation(s)
- Eva Bártová
- Veterinary and Pharmaceutical University, Palackého 1-3, 612 42, Brno, Czech Republic.
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19
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Behnke MS, Wootton JC, Lehmann MM, Radke JB, Lucas O, Nawas J, Sibley LD, White MW. Coordinated progression through two subtranscriptomes underlies the tachyzoite cycle of Toxoplasma gondii. PLoS One 2010; 5:e12354. [PMID: 20865045 PMCID: PMC2928733 DOI: 10.1371/journal.pone.0012354] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [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: 03/29/2010] [Accepted: 06/12/2010] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Apicomplexan parasites replicate by varied and unusual processes where the typically eukaryotic expansion of cellular components and chromosome cycle are coordinated with the biosynthesis of parasite-specific structures essential for transmission. METHODOLOGY/PRINCIPAL FINDINGS Here we describe the global cell cycle transcriptome of the tachyzoite stage of Toxoplasma gondii. In dividing tachyzoites, more than a third of the mRNAs exhibit significant cyclical profiles whose timing correlates with biosynthetic events that unfold during daughter parasite formation. These 2,833 mRNAs have a bimodal organization with peak expression occurring in one of two transcriptional waves that are bounded by the transition into S phase and cell cycle exit following cytokinesis. The G1-subtranscriptome is enriched for genes required for basal biosynthetic and metabolic functions, similar to most eukaryotes, while the S/M-subtranscriptome is characterized by the uniquely apicomplexan requirements of parasite maturation, development of specialized organelles, and egress of infectious daughter cells. Two dozen AP2 transcription factors form a series through the tachyzoite cycle with successive sharp peaks of protein expression in the same timeframes as their mRNA patterns, indicating that the mechanisms responsible for the timing of protein delivery might be mediated by AP2 domains with different promoter recognition specificities. CONCLUSION/SIGNIFICANCE Underlying each of the major events in apicomplexan cell cycles, and many more subordinate actions, are dynamic changes in parasite gene expression. The mechanisms responsible for cyclical gene expression timing are likely crucial to the efficiency of parasite replication and may provide new avenues for interfering with parasite growth.
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Affiliation(s)
- Michael S. Behnke
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - John C. Wootton
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Margaret M. Lehmann
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Josh B. Radke
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
- Departments of Molecular Medicine and Global Health, University of South Florida, Tampa, Florida, United States of America
| | - Olivier Lucas
- Departments of Molecular Medicine and Global Health, University of South Florida, Tampa, Florida, United States of America
| | - Julie Nawas
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - L. David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Michael W. White
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
- Departments of Molecular Medicine and Global Health, University of South Florida, Tampa, Florida, United States of America
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20
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Lorestani A, Sheiner L, Yang K, Robertson SD, Sahoo N, Brooks CF, Ferguson DJP, Striepen B, Gubbels MJ. A Toxoplasma MORN1 null mutant undergoes repeated divisions but is defective in basal assembly, apicoplast division and cytokinesis. PLoS One 2010; 5:e12302. [PMID: 20808817 PMCID: PMC2924399 DOI: 10.1371/journal.pone.0012302] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [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: 06/09/2010] [Accepted: 07/27/2010] [Indexed: 01/08/2023] Open
Abstract
The membrane occupation and recognition nexus protein 1 (MORN1) is highly conserved among apicomplexan parasites and is associated with several structures that have a role in cell division. Here we dissected the role of MORN1 using the relatively simple budding process of Toxoplasma gondii as a model. Ablation of MORN1 in a conditional null mutant resulted in pronounced defects suggesting a central role for MORN1 in apicoplast segregation and in daughter cell budding. Lack of MORN1 resulted in double-headed parasites. These Janus-headed parasites form two complete apical complexes but fail to assemble a basal complex. Moreover, these parasites were capable of undergoing several more budding rounds resulting in the formation of up to 16-headed parasites conjoined at the basal end. Despite this segregation defect, the mother's cytoskeleton was completely disassembled in every budding round. Overall this argues that successful completion of the budding is not required for cell cycle progression. None of the known basal complex components, including a set of recently identified inner membrane complex (IMC) proteins, localized correctly in these multi-headed parasites. These data suggest that MORN1 is essential for assembly of the basal complex, and that lack of the basal complex abolishes the contractile capacity assigned to the basal complex late in daughter formation. Consistent with this hypothesis we observe that MORN1 mutants fail to efficiently constrict and divide the apicoplast. We used the null background provided by the mutant to dissect the function of subdomains of the MORN1 protein. This demonstrated that deletion of a single MORN domain already prevented the function of MORN1 whereas a critical role for the short linker between MORN domains 6 and 7 was identified. In conclusion, MORN1 is required for basal complex assembly and loss of MORN1 results in defects in apicoplast division and daughter segregation.
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Affiliation(s)
- Alexander Lorestani
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Lilach Sheiner
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - Kevin Yang
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Seth D. Robertson
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Nivedita Sahoo
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Carrie F. Brooks
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - David J. P. Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Boris Striepen
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
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Affiliation(s)
- E A Innes
- Moredun Research Institute, Pentlands Science Park, Edinburgh, UK.
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Nagamune K. [Toxoplasma gondii as a plant: plant hormone and calcium signaling]. Tanpakushitsu Kakusan Koso 2009; 54:1047-1052. [PMID: 21089539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Gubbels MJ, Lehmann M, Muthalagi M, Jerome ME, Brooks CF, Szatanek T, Flynn J, Parrot B, Radke J, Striepen B, White MW. Forward genetic analysis of the apicomplexan cell division cycle in Toxoplasma gondii. PLoS Pathog 2008; 4:e36. [PMID: 18282098 PMCID: PMC2242837 DOI: 10.1371/journal.ppat.0040036] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [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: 10/31/2007] [Accepted: 01/07/2008] [Indexed: 11/18/2022] Open
Abstract
Apicomplexa are obligate intracellular pathogens that have fine-tuned their proliferative strategies to match a large variety of host cells. A critical aspect of this adaptation is a flexible cell cycle that remains poorly understood at the mechanistic level. Here we describe a forward genetic dissection of the apicomplexan cell cycle using the Toxoplasma model. By high-throughput screening, we have isolated 165 temperature sensitive parasite growth mutants. Phenotypic analysis of these mutants suggests regulated progression through the parasite cell cycle with defined phases and checkpoints. These analyses also highlight the critical importance of the peculiar intranuclear spindle as the physical hub of cell cycle regulation. To link these phenotypes to parasite genes, we have developed a robust complementation system based on a genomic cosmid library. Using this approach, we have so far complemented 22 temperature sensitive mutants and identified 18 candidate loci, eight of which were independently confirmed using a set of sequenced and arrayed cosmids. For three of these loci we have identified the mutant allele. The genes identified include regulators of spindle formation, nuclear trafficking, and protein degradation. The genetic approach described here should be widely applicable to numerous essential aspects of parasite biology.
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Affiliation(s)
- Marc-Jan Gubbels
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Margaret Lehmann
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Mani Muthalagi
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Maria E Jerome
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Carrie F Brooks
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Tomasz Szatanek
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Jayme Flynn
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America
| | - Ben Parrot
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Josh Radke
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, 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
- * To whom correspondence should be addressed. E-mail: (BS); (MWW)
| | - Michael W White
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
- * To whom correspondence should be addressed. E-mail: (BS); (MWW)
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Palm C, Tumani H, Pietzcker T, Bengel D. Diagnosis of cerebral toxoplasmosis by detection of Toxoplasma gondii tachyzoites in cerebrospinal fluid. J Neurol 2008; 255:939-41. [PMID: 18446314 DOI: 10.1007/s00415-008-0691-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 04/11/2007] [Accepted: 07/06/2007] [Indexed: 11/28/2022]
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Abstract
The apicomplexans are a large group of parasitic protozoa, many of which are important human and animal pathogens, including Plasmodium falciparum and Toxoplasma gondii. These parasites cause disease only when they replicate, and their replication is critically dependent on the proper assembly of the parasite cytoskeletons during cell division. In addition to their importance in pathogenesis, the apicomplexan parasite cytoskeletons are spectacular structures. Therefore, understanding the cytoskeletal biogenesis of these parasites is important not only for parasitology but also of general interest to broader cell biology. Previously, we found that the basal end of T. gondii contains a novel cytoskeletal assembly, the basal complex, a cytoskeletal compartment constructed in concert with the daughter cortical cytoskeleton during cell division. This study focuses on key events during the biogenesis of the basal complex using high resolution light microscopy, and reveals that daughter basal complexes are established around the duplicated centrioles independently of the structural integrity of the daughter cortical cytoskeleton, and that they are dynamic "caps" at the growing ends of the daughters. Compartmentation and polarization of the basal complex is first revealed at a late stage of cell division upon the recruitment of an EF-hand containing calcium binding protein, TgCentrin2. This correlates with the constriction of the basal complex, a process that can be artificially induced by increasing cellular calcium concentration. The basal complex is therefore likely to be a new kind of centrin-based contractile apparatus.
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Affiliation(s)
- Ke Hu
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America.
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Authier H, Cassaing S, Coste A, Balard P, Gales A, Berry A, Bans V, Bessières MH, Pipy B. Interleukin-13 primes iNO synthase expression induced by LPS in mouse peritoneal macrophages. Mol Immunol 2008; 45:235-43. [PMID: 17568676 DOI: 10.1016/j.molimm.2007.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 04/02/2007] [Accepted: 04/06/2007] [Indexed: 01/22/2023]
Abstract
Th2 cytokines such as interleukin-13 (IL-13) have both, stimulatory and inhibitory effects on effector functions of macrophages. Reactive nitrogen species are classically induced in Th1 cytokines and/or lipopolysaccharides (LPS) activated macrophages and this response is inhibited by IL-13. In contrast, IL-13 primes macrophages to produce NO in response to LPS when IL-13 treatment happens prior to LPS exposure. This mechanism occurs through a complex signalling pathway, which involves the scavenger receptor CD36, the LPS receptor CD14 and the nuclear receptor PPARgamma. The enhancement of NO production is the consequence of iNOS induction at mRNA and protein levels. The increase of the NO production induced by LPS in IL-13 pre-treated macrophages is found to potentiate the inhibition of Toxoplasma gondii intracellular replication. These results reveal a novel IL-13 signalling pathway that primes the antimicrobial activity of macrophages induced by LPS caused by overexpression of the iNOS-NO axis.
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Affiliation(s)
- Hélène Authier
- Laboratoire des macrophages, Médiateurs de l'Inflammation et Interactions Cellulaires, Université Paul Sabatier Toulouse III, EA2405, INSERM IFR31 BP84225, 31432 Toulouse, Cedex 4, France
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28
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Pino P, Foth BJ, Kwok LY, Sheiner L, Schepers R, Soldati T, Soldati-Favre D. Dual targeting of antioxidant and metabolic enzymes to the mitochondrion and the apicoplast of Toxoplasma gondii. PLoS Pathog 2007; 3:e115. [PMID: 17784785 PMCID: PMC1959373 DOI: 10.1371/journal.ppat.0030115] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [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: 04/02/2007] [Accepted: 06/27/2007] [Indexed: 01/05/2023] Open
Abstract
Toxoplasma gondii is an aerobic protozoan parasite that possesses mitochondrial antioxidant enzymes to safely dispose of oxygen radicals generated by cellular respiration and metabolism. As with most Apicomplexans, it also harbors a chloroplast-like organelle, the apicoplast, which hosts various biosynthetic pathways and requires antioxidant protection. Most apicoplast-resident proteins are encoded in the nuclear genome and are targeted to the organelle via a bipartite N-terminal targeting sequence. We show here that two antioxidant enzymes—a superoxide dismutase (TgSOD2) and a thioredoxin-dependent peroxidase (TgTPX1/2)—and an aconitase are dually targeted to both the apicoplast and the mitochondrion of T. gondii. In the case of TgSOD2, our results indicate that a single gene product is bimodally targeted due to an inconspicuous variation within the putative signal peptide of the organellar protein, which significantly alters its subcellular localization. Dual organellar targeting of proteins might occur frequently in Apicomplexans to serve important biological functions such as antioxidant protection and carbon metabolism. Toxoplasma gondii is a human and animal pathogen representative of the large group of Apicomplexa. Most members of this phylum contain, in addition to a tubular mitochondrion, a second endosymbiotic organelle indispensable for parasite survival, called the apicoplast. This non-photosynthetic plastid is the site of several anabolic pathways, including the biosynthesis of fatty acids, isoprenoids, iron-sulphur cluster, and heme. Virtually all enzymes active inside the apicoplast are encoded by the nuclear genome and targeted to the organelle via the endoplasmic reticulum courtesy of a bipartite amino terminal recognition sequence. The metabolic activities of the apicoplast impose a high demand for antioxidant protection. We show here that T. gondii possesses a superoxide dismutase and a peroxidase that are shared between the two organelles by an unusual mechanism of bimodal targeting whereby the nature of the signal peptide influences the destination of the protein to both organelles. Dual targeting also extends to other classical metabolic enzymes such as aconitase, uncovering unexpected metabolic pathways occurring in these organelles. In consequence, the bioinformatic predictions for plastidic or mitochondrial targeting on the basis of the characteristics of N-terminal presequences are insufficient in the absence of an experimental confirmation.
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Affiliation(s)
- Paco Pino
- Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, Geneva, Switzerland
| | - Bernardo Javier Foth
- Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, Geneva, Switzerland
| | - Lai-Yu Kwok
- Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, Geneva, Switzerland
| | - Lilach Sheiner
- Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, Geneva, Switzerland
| | - Rebecca Schepers
- Department of Biological Sciences, Imperial College London, London, United Kingdom
| | - Thierry Soldati
- Department of Biochemistry, Sciences II, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Centre Medical Universitaire, University of Geneva, Geneva, Switzerland
- * To whom correspondence should be addressed. E-mail:
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Van TT, Kim SK, Camps M, Boothroyd JC, Knoll LJ. The BSR4 protein is up-regulated in Toxoplasma gondii bradyzoites, however the dominant surface antigen recognised by the P36 monoclonal antibody is SRS9. Int J Parasitol 2007; 37:877-85. [PMID: 17368655 DOI: 10.1016/j.ijpara.2007.02.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [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: 12/04/2006] [Revised: 01/30/2007] [Accepted: 02/05/2007] [Indexed: 11/19/2022]
Abstract
The protozoan parasite, Toxoplasma gondii, interconverts between fast-growing tachyzoites and slow-growing bradyzoites within intermediate hosts. The surface of T. gondii is covered by the SAG1-related sequence (SRS) superfamily of glycosyl phosphatidyl inositol-anchored proteins, many of which are stage-specific. Previous transient transfection of BSR4, a member of the SRS superfamily, showed reactivity with the bradyzoite-specific P36 mAb by immunofluorescene assay. BSR4 mRNA levels were equally abundant in tachyzoites and bradyzoites, suggesting post-transcriptional regulation of the protein. In this study, we show that BSR4 protein is present in both tachyzoites and bradyzoites, but up-regulated in bradyzoites. However, stable expression of BSR4 in two BSR4-negative T. gondii strains shows minimal reactivity to the P36 mAb by Western immunoblotting, even though the BSR4 protein is abundant. We discovered that the SRS9 protein, a bradyzoite-specific member of the SRS superfamily and encoded immediately downstream of BSR4, was also ablated in the BSR4-negative strains, suggesting that SRS9 is the surface antigen recognised by the P36 mAb. Stable expression of SRS9 in the BSR4 mutant strains shows robust reactivity to the P36 mAb. Immunoprecipitation experiments confirm that the P36 mAb interacts with the SRS9 protein. These data indicate that while the BSR4 protein is up-regulated in bradyzoites, the dominant antigen that the P36 mAb recognises is SRS9.
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Affiliation(s)
- Tam T Van
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
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30
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Sautel CF, Cannella D, Bastien O, Kieffer S, Aldebert D, Garin J, Tardieux I, Belrhali H, Hakimi MA. SET8-mediated methylations of histone H4 lysine 20 mark silent heterochromatic domains in apicomplexan genomes. Mol Cell Biol 2007; 27:5711-24. [PMID: 17562855 PMCID: PMC1952134 DOI: 10.1128/mcb.00482-07] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [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: 11/20/2022] Open
Abstract
Posttranslational histone modifications modulate chromatin-templated processes in various biological systems. H4K20 methylation is considered to have an evolutionarily ancient role in DNA repair and genome integrity, while its function in heterochromatin function and gene expression is thought to have arisen later during evolution. Here, we identify and characterize H4K20 methylases of the Set8 family in Plasmodium and Toxoplasma, two medically important members of the protozoan phylum Apicomplexa. Remarkably, parasite Set8-related proteins display H4K20 mono-, di-, and trimethylase activities, in striking contrast to the monomethylase-restricted human Set8. Structurally, few residues forming the substrate-specific channel dictate enzyme methylation multiplicity. These enzymes are cell cycle regulated and focally enriched at pericentric and telomeric heterochromatin in both parasites. Collectively, our findings provide new insights into the evolution of Set8-mediated biochemical pathways, suggesting that the heterochromatic function of the marker is not restricted to metazoans. Thus, these lower eukaryotes have developed a diverse panel of biological stages through their high capacity to differentiate, and epigenetics only begins to emerge as a strong determinant of their biology.
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Affiliation(s)
- Céline F Sautel
- UMR5163/CNRS-Joseph Fourier University, Jean-Roget Institute, Grenoble F-38042, France
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31
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Fleige T, Fischer K, Ferguson DJP, Gross U, Bohne W. Carbohydrate metabolism in the Toxoplasma gondii apicoplast: localization of three glycolytic isoenzymes, the single pyruvate dehydrogenase complex, and a plastid phosphate translocator. Eukaryot Cell 2007; 6:984-96. [PMID: 17449654 PMCID: PMC1951530 DOI: 10.1128/ec.00061-07] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many apicomplexan parasites, such as Toxoplasma gondii and Plasmodium species, possess a nonphotosynthetic plastid, referred to as the apicoplast, which is essential for the parasites' viability and displays characteristics similar to those of nongreen plastids in plants. In this study, we localized several key enzymes of the carbohydrate metabolism of T. gondii to either the apicoplast or the cytosol by engineering parasites which express epitope-tagged fusion proteins. The cytosol contains a complete set of enzymes for glycolysis, which should enable the parasite to metabolize imported glucose into pyruvate. All the glycolytic enzymes, from phosphofructokinase up to pyruvate kinase, are present in the T. gondii genome, as duplicates and isoforms of triose phosphate isomerase, phosphoglycerate kinase, and pyruvate kinase were found to localize to the apicoplast. The mRNA expression levels of all genes with glycolytic products were compared between tachyzoites and bradyzoites; however, a strict bradyzoite-specific expression pattern was observed only for enolase I. The T. gondii genome encodes a single pyruvate dehydrogenase complex, which was located in the apicoplast and absent in the mitochondrion, as shown by targeting of epitope-tagged fusion proteins and by immunolocalization of the native pyruvate dehydrogenase complex. The exchange of metabolites between the cytosol and the apicoplast is likely to be mediated by a phosphate translocator which was localized to the apicoplast. Based on these localization studies, a model is proposed that explains the supply of the apicoplast with ATP and the reduction power, as well as the exchange of metabolites between the cytosol and the apicoplast.
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Affiliation(s)
- Tobias Fleige
- Institute of Medical Microbiology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany
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32
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Molestina RE, Sinai AP. Host and parasite-derived IKK activities direct distinct temporal phases of NF-kappaB activation and target gene expression following Toxoplasma gondii infection. J Cell Sci 2007; 118:5785-96. [PMID: 16339966 DOI: 10.1242/jcs.02709] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [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: 01/06/2023] Open
Abstract
Activation of NF-kappaB by the intracellular pathogen Toxoplasma gondii is associated with the localization of phosphorylated IkappaB alpha to the parasitophorous vacuole membrane (PVM). This is mediated by a parasite-derived IkappaB kinase (TgIKK) activity and is independent of host IKK function. In the present study, we examined the roles of host IKK and parasite-derived TgIKK on the temporal modulation of NF-kappaB activation. Despite the presence of TgIKK activity at the PVM, nuclear translocation of NF-kappaB and subsequent gene expression exhibited a requirement for the host IKK complex. A detailed kinetic analysis of NF-kappaB activation revealed a biphasic, hierarchical and temporally regulated response. We propose a novel paradigm for the modulation of NF-kappaB-dependent gene expression by T. gondii that involves both the host IKK complex and TgIKK activity at different phases of infection. Thus, T. gondii effectively alters gene expression in a temporal dimension by exploiting the NF-kappaB signaling machinery and subsequently rewiring the activation circuits of the infected host cell.
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Affiliation(s)
- Robert E Molestina
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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Gilk SD, Raviv Y, Hu K, Murray JM, Beckers CJM, Ward GE. Identification of PhIL1, a novel cytoskeletal protein of the Toxoplasma gondii pellicle, through photosensitized labeling with 5-[125I]iodonaphthalene-1-azide. Eukaryot Cell 2006; 5:1622-34. [PMID: 17030994 PMCID: PMC1595352 DOI: 10.1128/ec.00114-06] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The pellicle of the protozoan parasite Toxoplasma gondii is a unique triple bilayer structure, consisting of the plasma membrane and two tightly apposed membranes of the underlying inner membrane complex. Integral membrane proteins of the pellicle are likely to play critical roles in host cell recognition, attachment, and invasion, but few such proteins have been identified. This is in large part because the parasite surface is dominated by a family of abundant and highly immunogenic glycosylphosphatidylinositol (GPI)-anchored proteins, which has made the identification of non-GPI-linked proteins difficult. To identify such proteins, we have developed a radiolabeling approach using the hydrophobic, photoactivatable compound 5-[(125)I]iodonaphthalene-1-azide (INA). INA can be activated by photosensitizing fluorochromes; by restricting these fluorochromes to the pellicle, [(125)I]INA labeling will selectively target non-GPI-anchored membrane-embedded proteins of the pellicle. We demonstrate here that three known membrane proteins of the pellicle can indeed be labeled by photosensitization with INA. In addition, this approach has identified a novel 22-kDa protein, named PhIL1 (photosensitized INA-labeled protein 1), with unexpected properties. While the INA labeling of PhIL1 is consistent with an integral membrane protein, the protein has neither a transmembrane domain nor predicted sites of lipid modification. PhIL1 is conserved in apicomplexan parasites and localizes to the parasite periphery, concentrated at the apical end just basal to the conoid. Detergent extraction and immunolocalization data suggest that PhIL1 associates with the parasite cytoskeleton.
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Affiliation(s)
- Stacey D Gilk
- Department of Microbiology and Molecular Genetics, 316 Stafford Hall, University of Vermont, Burlington, VT 05405, USA
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Abstract
Efficient and rapid host cell invasion is a prerequisite for an intracellular parasitic life style. Pathogens typically induce receptor-mediated endocytosis and hijack the force-transducing system of a host cell to gain access to a replication-competent niche. In striking contrast, apicomplexan parasites such as Plasmodium, the causative agent of malaria, and the human and animal pathogens Toxoplasma and Cryptosporidium employ their own actomyosin motor machinery to propel themselves into prospective host cells. Understanding the regulation and dynamics of actin-based motility of these parasites is therefore central to understanding their pathogenesis. The parasite genomes harbour surprisingly few potential actin-regulatory proteins indicating that a basic repertoire meets the requirements to regulate actin dynamics. In this article, we summarize our current knowledge of Plasmodium microfilament dynamics and describe its potential players.
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Affiliation(s)
- Herwig Schüler
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany.
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Tonkin CJ, Roos DS, McFadden GI. N-terminal positively charged amino acids, but not their exact position, are important for apicoplast transit peptide fidelity in Toxoplasma gondii. Mol Biochem Parasitol 2006; 150:192-200. [PMID: 16963133 DOI: 10.1016/j.molbiopara.2006.08.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 08/02/2006] [Accepted: 08/03/2006] [Indexed: 11/17/2022]
Abstract
The non-photosynthetic plastid - or apicoplast - of Toxoplasma gondii and other apicomplexan parasites is an essential organelle and promising drug target. Most apicoplast proteins are encoded in the nucleus and targeted into the organelle through the apicoplast's four membranes courtesy of a bipartite N-terminal leader sequence comprising of an endomembrane signal peptide followed by a plastid transit peptide. Apicoplast transit peptides, like plant plastid transit peptides, have no primary consensus, are variable in length and may be distinguishable only by a relative depletion of negative charged residues and consequent enrichment in basic residues. In this study we examine the role of charged residues within an apicoplast transit peptide in T. gondii by point mutagenesis. We demonstrate that positive charged residues, combined with the absence of negatively charged amino acids, are essential for apicoplast transit peptide fidelity, as also observed in P. falciparum. Furthermore, we show that positive charge is more important at the transit peptide's N-terminus than its C-terminus, and that the nature of the positive residue and the exact position of the N-terminal positive charge are not important. These results suggest that a simple, rule-based prediction for T. gondii transit peptides, similar to that successfully implemented for P. falciparum should help to identify apicoplast proteins and facilitate the identification of drug targets in this important human pathogen.
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Affiliation(s)
- Christopher J Tonkin
- Plant Cell Biology Research Centre, The School of Botany, The University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia
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36
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Mazumdar J, H. Wilson E, Masek K, A. Hunter C, Striepen B. Apicoplast fatty acid synthesis is essential for organelle biogenesis and parasite survival in Toxoplasma gondii. Proc Natl Acad Sci U S A 2006; 103:13192-7. [PMID: 16920791 PMCID: PMC1559775 DOI: 10.1073/pnas.0603391103] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [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] [Indexed: 12/21/2022] Open
Abstract
Apicomplexan parasites are the cause of numerous important human diseases including malaria and AIDS-associated opportunistic infections. Drug treatment for these diseases is not satisfactory and is threatened by resistance. The discovery of the apicoplast, a chloroplast-like organelle, presents drug targets unique to these parasites. The apicoplast-localized fatty acid synthesis (FAS II) pathway, a metabolic process fundamentally divergent from the analogous FAS I pathway in humans, represents one such target. However, the specific biological roles of apicoplast FAS II remain elusive. Furthermore, the parasite genome encodes additional and potentially redundant pathways for the synthesis of fatty acids. We have constructed a conditional null mutant of acyl carrier protein, a central component of the FAS II pathway in Toxoplasma gondii. Loss of FAS II severely compromises parasite growth in culture. We show FAS II to be required for the activation of pyruvate dehydrogenase, an important source of the metabolic precursor acetyl-CoA. Interestingly, acyl carrier protein knockout also leads to defects in apicoplast biogenesis and a consequent loss of the organelle. Most importantly, in vivo knockdown of apicoplast FAS II in a mouse model results in cure from a lethal challenge infection. In conclusion, our study demonstrates a direct link between apicoplast FAS II functions and parasite survival and pathogenesis. Our genetic model also offers a platform to dissect the integration of the apicoplast into parasite metabolism, especially its postulated interaction with the mitochondrion.
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Affiliation(s)
| | - Emma H. Wilson
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104
| | - Kate Masek
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104
| | - Christopher A. Hunter
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104
| | - Boris Striepen
- *Department of Cellular Biology and
- Center for Tropical and Emerging Global Diseases, University of Georgia, Paul D. Coverdell Center, 500 D. W. Brooks Drive, Athens, GA 30602; and
- To whom correspondence should be addressed. E-mail:
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Keller P, Schaumburg F, Fischer SF, Häcker G, Gross U, Lüder CGK. Direct inhibition of cytochrome c-induced caspase activation in vitro by Toxoplasma gondii reveals novel mechanisms of interference with host cell apoptosis. FEMS Microbiol Lett 2006; 258:312-9. [PMID: 16640590 DOI: 10.1111/j.1574-6968.2006.00241.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The intracellular parasite Toxoplasma gondii is known to inhibit apoptosis of its host cell. The molecular mechanisms of this interference are, however, not yet completely understood. We show here that viable parasites prominently inhibited the activation of caspase 3/7 induced by cytochrome c, dATP and dithiothreitol in cytosolic extracts of human-derived Jurkat leukemic T cells. In contrast, granzyme B-induced caspase activity was only slightly diminished. De novo protein biosynthesis by T. gondii was dispensable for the inhibition of cytochrome c-induced caspase activation. Furthermore, a complete parasite lysate or, more importantly, molecules released by extracellular parasites mediated the interaction with the caspase cascade. The cell-free system applied here is thus a valuable tool to study the interaction of T. gondii and possibly other intracellular pathogens with host cell apoptosis.
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Affiliation(s)
- Philine Keller
- Institut für Medizinische Mikrobiologie, Georg-August-Universität, Göttingen, Germany
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Abstract
In this issue of Cell, Coppens and coworkers (Coppens et al., 2006) describe how Toxoplasma gondii, an obligate intracellular parasite, feeds on the host. Coppens et al. provide evidence that the parasite takes host cell endosomes and lysosomes hostage by sequestering them where the parasite resides, within invaginations of the parasitophorous vacuole.
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Affiliation(s)
- Jean Gruenberg
- Department of Biochemistry, University of Geneva, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland
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Martins-Duarte ES, Urbina JA, de Souza W, Vommaro RC. Antiproliferative activities of two novel quinuclidine inhibitors against Toxoplasma gondii tachyzoites in vitro. J Antimicrob Chemother 2006; 58:59-65. [PMID: 16702175 DOI: 10.1093/jac/dkl180] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To study the antiproliferative effects of ER119884 and E5700, two quinuclidine-based inhibitors of squalene synthase (SQS), against Toxoplasma gondii tachyzoites in epithelial cells. METHODS The antiproliferative effects of the quinuclidine derivatives, alone or in combination with epiminolanosterol or antifolates, were analysed, resulting in the construction of isobolograms. The ultrastructure of treated tachyzoites was analysed by transmission electron microscopy. RESULTS The quinuclidine derivatives demonstrated selective anti-T. gondii activity, arresting parasite growth with IC50 values of 0.66 and 0.23 microM for ER119884 and E5700, respectively, after 24 h of interaction and 0.44 and 0.19 microM after 48 h of interaction. Both compounds induced remarkable alterations in the parasite ultrastructure, such as mitochondrial swelling and the presence of autophagosome-like structures, after 24 h of treatment. Combination of these quinuclidine derivatives with the antifolates sulfadiazine and pyrimethamine produced a synergic effect. When epiminolanosterol was combined with E5700, the effect observed was synergic, whereas the combination with ER119884 produced no interaction. CONCLUSIONS E5700 and ER119884 demonstrated selective activity against T. gondii tachyzoites and are a possible alternative to be used in association with the current therapy. The ultrastructural alterations observed suggest a possible interference with lipid metabolism.
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Affiliation(s)
- Erica S Martins-Duarte
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho CCS Universidade Federal do Rio de Janeiro, 21949-900-Rio de Janeiro-RJ, Brazil
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Gubbels MJ, Vaishnava S, Boot N, Dubremetz JF, Striepen B. A MORN-repeat protein is a dynamic component of the Toxoplasma gondii cell division apparatus. J Cell Sci 2006; 119:2236-45. [PMID: 16684814 DOI: 10.1242/jcs.02949] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apicomplexan parasites divide and replicate through a complex process of internal budding. Daughter cells are preformed within the mother on a cytoskeletal scaffold, endowed with a set of organelles whereby in the final stages the mother disintegrates and is recycled in the emerging daughters. How the cytoskeleton and the various endomembrane systems interact in this dynamic process remains poorly understood at the molecular level. Through a random YFP fusion screen we have identified two Toxoplasma gondii proteins carrying multiple membrane occupation and recognition nexus (MORN) motifs. MORN1 is highly conserved among apicomplexans. MORN1 specifically localizes to ring structures at the apical and posterior end of the inner membrane complex and to the centrocone, a specialized nuclear structure that organizes the mitotic spindle. Time-lapse imaging of tagged MORN1 revealed that these structures are highly dynamic and appear to play a role in nuclear division and daughter cell budding. Overexpression of MORN1 resulted in severe but specific defects in nuclear segregation and daughter cell formation. We hypothesize that MORN1 functions as a linker protein between certain membrane regions and the parasite's cytoskeleton. Our initial biochemical analysis is consistent with this model. Whereas recombinant MORN1 produced in bacteria is soluble, in the parasite MORN1 was associated with the cytoskeleton after detergent extraction.
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Affiliation(s)
- Marc-Jan Gubbels
- Center for Tropical and Emerging Global Diseases, University of Georgia, Paul D. Coverdell Center, Athens, 30602, USA
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Abstract
The Toxoplasma gondii phosphoinositide-specific phospholipase C gene (TgPI-PLC) was cloned, sequenced and expressed in Escherichia coli and its enzymatic characteristics were investigated. TgPI-PLC is present in the genome as a single-copy gene consisting of 22 exons interrupted by 21 introns, and encodes a polypeptide of 1097 amino acids with a predicted molecular mass of 121 kDa. In addition to the conserved catalytic X and Y domains, TgPI-PLC contains an apparent N-terminal PH domain, an EF hand motif and a C-terminal C2 domain. When compared with mammalian delta-type PI-PLC, TgPI-PLC has an additional extended N-terminus and two insertions in the region between the X and Y domains, with a 31-35% identity over the whole sequence. Recombinant TgPI-PLC, as well as the native enzyme obtained from crude membrane extracts of the parasite, was more active with phosphatidylinositol than with phosphatidylinositol 4,5-bisphosphate as substrate. Indirect immunofluorescence analysis using an affinity-purified antibody against TgPI-PLC revealed that this enzyme localizes in the plasma membrane of the parasites.
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Affiliation(s)
- Jianmin Fang
- *Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, The University of Georgia, Athens, GA 30602, U.S.A
| | - Norma Marchesini
- †Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, University of Illinois at Urbana-Champaign, Urbana, IL 61802, U.S.A
| | - Silvia N. J. Moreno
- *Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, The University of Georgia, Athens, GA 30602, U.S.A
- †Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, University of Illinois at Urbana-Champaign, Urbana, IL 61802, U.S.A
- To whom correspondence should be addressed (email )
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Dalmasso MC, Echeverria PC, Zappia MP, Hellman U, Dubremetz JF, Angel SO. Toxoplasma gondii has two lineages of histones 2b (H2B) with different expression profiles. Mol Biochem Parasitol 2006; 148:103-7. [PMID: 16621068 DOI: 10.1016/j.molbiopara.2006.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 03/09/2006] [Accepted: 03/13/2006] [Indexed: 11/24/2022]
Affiliation(s)
- María C Dalmasso
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM, Camino de Circunvalación Laguna, Prov. Buenos Aires, Argentina
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Coppens I, Dunn JD, Romano JD, Pypaert M, Zhang H, Boothroyd JC, Joiner KA. Toxoplasma gondii Sequesters Lysosomes from Mammalian Hosts in the Vacuolar Space. Cell 2006; 125:261-74. [PMID: 16630815 DOI: 10.1016/j.cell.2006.01.056] [Citation(s) in RCA: 243] [Impact Index Per Article: 13.5] [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: 08/04/2005] [Revised: 11/29/2005] [Accepted: 01/20/2006] [Indexed: 11/20/2022]
Abstract
The intracellular compartment harboring Toxoplasma gondii satisfies the parasite's nutritional needs for rapid growth in mammalian cells. We demonstrate that the parasitophorous vacuole (PV) of T. gondii accumulates material coming from the host mammalian cell via the exploitation of the host endo-lysosomal system. The parasite actively recruits host microtubules, resulting in selective attraction of endo-lysosomes to the PV. Microtubule-based invaginations of the PV membrane serve as conduits for the delivery of host endo-lysosomes within the PV. These tubular conduits are decorated by a parasite coat, including the tubulogenic protein GRA7, which acts like a garrote that sequesters host endocytic organelles in the vacuolar space. These data define an unanticipated process allowing the parasite intimate and concentrated access to a diverse range of low molecular weight components produced by the endo-lysosomal system. More generally, they identify a unique mechanism for unidirectional transport and sequestration of host organelles.
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Affiliation(s)
- Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
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Bhatti MM, Livingston M, Mullapudi N, Sullivan WJ. Pair of unusual GCN5 histone acetyltransferases and ADA2 homologues in the protozoan parasite Toxoplasma gondii. Eukaryot Cell 2006; 5:62-76. [PMID: 16400169 PMCID: PMC1360262 DOI: 10.1128/ec.5.1.62-76.2006] [Citation(s) in RCA: 42] [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] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
GCN5 is a histone acetyltransferase (HAT) essential for development in mammals and critical to stress responses in yeast. The protozoan parasite Toxoplasma gondii is a serious opportunistic pathogen. The study of epigenetics and gene expression in this ancient eukaryote has pharmacological relevance and may facilitate the understanding of these processes in higher eukaryotes. Here we show that the disruption of T. gondii GCN5 yields viable parasites, which were subsequently employed in a proteomics study to identify gene products affected by its loss. Promoter analysis of these TgGCN5-dependent genes, which were mostly parasite specific, reveals a conserved T-rich element. The loss of TgGCN5 does not attenuate virulence in an in vivo mouse model. We also discovered that T. gondii is the only invertebrate reported to date possessing a second GCN5 (TgGCN5-B). TgGCN5-B harbors a strikingly divergent N-terminal domain required for nuclear localization. Despite high homology between the HAT domains, the two TgGCN5s exhibit differing substrate specificities. In contrast to TgGCN5-A, which exclusively targets lysine 18 of H3, TgGCN5-B acetylates multiple lysines in the H3 tail. We also identify two ADA2 homologues that interact differently with the TgGCN5s. TgGCN5-B has the potential to compensate for TgGCN5-A, which probably arose from a gene duplication unique to T. gondii. Our work reveals an unexpected complexity in the GCN5 machinery of this primitive eukaryote.
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Affiliation(s)
- Micah M Bhatti
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Medical Sciences Building, Room A-525, Indianapolis, Indiana 46202-5120, USA
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45
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de Miguel N, Echeverria PC, Angel SO. Differential subcellular localization of members of the Toxoplasma gondii small heat shock protein family. Eukaryot Cell 2006; 4:1990-7. [PMID: 16339717 PMCID: PMC1317493 DOI: 10.1128/ec.4.12.1990-1997.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The results of this study describe the identification and characterization of the Toxoplasma gondii alpha-crystallin/small heat shock protein (sHsp) family. By database (www.toxodb.org) search, five parasite sHsps (Hsp20, Hsp21, Hsp28, Hsp29, and the previously characterized Hsp30/Bag1) were identified. As expected, they share the homologous alpha-crystallin domain, which is the key characteristic of sHsps. However, the N-terminal segment of each protein contains unique characteristics in size and sequence. Most T. gondii sHsps are constitutively expressed in tachyzoites and fully differentiated bradyzoites, with the exception of Hsp30/Bag1. Interestingly, by subcellular localization we observed that T. gondii sHsps are located in different compartments. Hsp20 is located at the apical end of the cell, Hsp28 is located inside the mitochondrion, Hsp29 showed a membrane-associated labeling, and Hsp21 appeared throughout the cytosol of the parasites. These particular differences in the immunostaining patterns suggest that their targets and functions might be different.
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Affiliation(s)
- N de Miguel
- Laboratorio de Parasitología Molecular, IIB-INTECH, Camino Circunvalación Laguna Km6, C.C 164, 7130 Chascomús, Prov. Buenos Aires, Argentina
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46
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Chini E, Nagamune K, Wetzel D, Sibley L. Evidence that the cADPR signalling pathway controls calcium-mediated microneme secretion in Toxoplasma gondii. Biochem J 2005; 389:269-77. [PMID: 15773818 PMCID: PMC1175103 DOI: 10.1042/bj20041971] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [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
The protozoan parasite Toxoplasma gondii relies on calcium-mediated exocytosis to secrete adhesins on to its surface where they can engage host cell receptors. Increases in intracellular calcium occur in response to Ins(1,4,5)P3 and caffeine, an agonist of ryanodine-responsive calcium-release channels. We examined lysates and microsomes of T. gondii and detected evidence of cADPR (cyclic ADP ribose) cyclase and hydrolase activities, the two enzymes that control the second messenger cADPR, which causes calcium release from RyR (ryanodine receptor). We also detected endogenous levels of cADPR in extracts of T. gondii. Furthermore, T. gondii microsomes that were loaded with 45Ca2+ released calcium when treated with cADPR, and the RyR antagonists 8-bromo-cADPR and Ruthenium Red blocked this response. Although T. gondii microsomes also responded to Ins(1,4,5)P3, the inhibition profiles of these calcium-release channels were mutually exclusive. The RyR antagonists 8-bromo-cADPR and dantrolene inhibited protein secretion and motility in live parasites. These results indicate that RyR calcium-release channels that respond to the second-messenger cADPR play an important role in regulating intracellular Ca2+, and hence host cell invasion, in protozoan parasites.
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Affiliation(s)
- Eduardo N. Chini
- *Department of Anesthesiology, Mayo Medical School, Mayo Clinic and Foundation, Rochester, MN 55905, U.S.A
| | - Kisaburo Nagamune
- †Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, U.S.A
| | - Dawn M. Wetzel
- †Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, U.S.A
| | - L. David Sibley
- †Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, U.S.A
- To whom correspondence should be addressed (email )
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Harb OS, Chatterjee B, Fraunholz MJ, Crawford MJ, Nishi M, Roos DS. Multiple functionally redundant signals mediate targeting to the apicoplast in the apicomplexan parasite Toxoplasma gondii. Eukaryot Cell 2005; 3:663-74. [PMID: 15189987 PMCID: PMC420125 DOI: 10.1128/ec.3.3.663-674.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most species of the protozoan phylum Apicomplexa harbor an endosymbiotic organelle--the apicoplast--acquired when an ancestral parasite engulfed a eukaryotic plastid-containing alga. Several hundred proteins are encoded in the parasite nucleus and are posttranslationally targeted to the apicoplast by a distinctive bipartite signal. The N-terminal 20 to 30 amino acids of nucleus-encoded apicoplast targeted proteins function as a classical signal sequence, mediating entry into the secretory pathway. Cleavage of the signal sequence exposes a transit peptide of variable length (50 to 200 amino acids) that is required for directing proteins to the apicoplast. Although these peptides are enriched in basic amino acids, their structural and functional characteristics are not well understood, which hampers the identification of apicoplast proteins that may constitute novel chemotherapeutic targets. To identify functional domains for a model apicoplast transit peptide, we generated more than 80 deletions and mutations throughout the transit peptide of Toxoplasma gondii ferredoxin NADP+ reductase (TgFNR) and examined the ability of these altered transit peptides to mediate proper targeting and processing of a fluorescent protein reporter. These studies revealed the presence of numerous functional domains. Processing can take place at multiple sites in the protein sequence and may occur outside of the apicoplast lumen. The TgFNR transit peptide contains at least two independent and functionally redundant targeting signals, each of which contains a subdomain that is required for release from or proper sorting within the endoplasmic reticulum. Certain deletion constructs traffic to multiple locations, including the apicoplast periphery, the rhoptries, and the parasitophorous vacuole, suggesting a common thread for targeting to these specialized compartments.
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Affiliation(s)
- Omar S Harb
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
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48
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Hajj HE, Lebrun M, Fourmaux MN, Vial H, Dubremetz JF. Characterization, biosynthesis and fate of ROP7, a ROP2 related rhoptry protein of Toxoplasma gondii. Mol Biochem Parasitol 2005; 146:98-100. [PMID: 16330111 DOI: 10.1016/j.molbiopara.2005.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 10/06/2005] [Accepted: 10/14/2005] [Indexed: 11/29/2022]
Affiliation(s)
- Hiba El Hajj
- UMR5539 CNRS, Université de Montpellier 2, Place E Bataillon, 34095 Montpellier, France
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49
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Hartmann J, Hu K, He CY, Pelletier L, Roos DS, Warren G. Golgi and centrosome cycles in Toxoplasma gondii. Mol Biochem Parasitol 2005; 145:125-7. [PMID: 16266757 DOI: 10.1016/j.molbiopara.2005.09.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Revised: 09/19/2005] [Accepted: 09/23/2005] [Indexed: 11/21/2022]
Affiliation(s)
- Jan Hartmann
- Department of Cell Biology, Ludwig Institute for Cancer Research, Yale University School of Medicine, New Haven, CT 06520, USA
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50
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Pfluger SL, Goodson HV, Moran JM, Ruggiero CJ, Ye X, Emmons KM, Hager KM. Receptor for retrograde transport in the apicomplexan parasite Toxoplasma gondii. Eukaryot Cell 2005; 4:432-42. [PMID: 15701805 PMCID: PMC549326 DOI: 10.1128/ec.4.2.432-442.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Toxoplasma gondii and its apicomplexan relatives (such as Plasmodium falciparum, which causes malaria) are obligate intracellular parasites that rely on sequential protein release from specialized secretory organelles for invasion and multiplication within host cells. Because of the importance of these unusual membrane trafficking pathways for drug development and comparative cell biology, characterizing them is essential. In particular, it is unclear what role retrieval mechanisms play in parasite membrane trafficking or where they operate. Previously, we showed that T. gondii's beta-COP (TgBetaCOP; a subunit of coatomer protein complex I, COPI) and retrieval reporters localize exclusively to the zone between the parasite endoplasmic reticulum (ER) and Golgi apparatus. This suggested the existence of an HDEL receptor in T. gondii. We have now identified, cloned, and sequenced this receptor, TgERD2. TgERD2 localizes in a Golgi or ER pattern suggestive of the HDEL retrieval reporter (K. M. Hager, B. Striepen, L. G. Tilney, and D. S. Roos, J. Cell Sci. 112:2631-2638, 1999). A functional assay reveals that TgERD2 is able to complement the Saccharomyces cerevisiae ERD2 null mutant. Retrieval studies reveal that stable expression of a fluorescent exogenous retrieval ligand results in a dispersal of betaCOP signal throughout the cytoplasm and, surprisingly, results in betaCOP staining of the vacuolar space of the parasite. In contrast, stable expression of TgERD2GFP does not appear to disturb betaCOP staining. In addition to TgERD2, Toxoplasma contains two more divergent ERD2 relatives. Phylogenetic analysis reveals that these proteins belong to a previously unrecognized ERD2 subfamily common to plants and alveolate organisms and as such could represent mediators of parasite-specific retrieval functions. No evidence of class 2 ERD2 proteins was found in metazoan organisms or fungi.
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Affiliation(s)
- Stacy L Pfluger
- Department of Biological Sciences, Center for Tropical Disease Research and Training, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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