1
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Carruthers VB, Dou Z. Deciphering protein prenylation in endocytic trafficking in Toxoplasma gondii. mBio 2024; 15:e0028324. [PMID: 38407123 PMCID: PMC11005354 DOI: 10.1128/mbio.00283-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024] Open
Abstract
Toxoplasma gondii is a widespread intracellular protozoan pathogen infecting virtually all warm-blooded animals. This parasite acquires host-derived resources to support its replication inside a membrane-bound parasitophorous vacuole within infected host cells. Previous research has discovered that Toxoplasma actively endocytoses host proteins and transports them to a lysosome-equivalent structure for digestion. However, few molecular determinants required for trafficking of host-derived material within the parasite were known. A recent study (Q.-Q. Wang, M. Sun, T. Tang, D.-H. Lai, et al., mBio 14:e01309-23, 2023, https://doi.org/10.1128/mbio.01309-23) identified a critical role for membrane anchoring of proteins via prenylation in the trafficking of endocytosed host proteins by Toxoplasma, including an essential Toxoplasma ortholog of Rab1B. The authors also found that TgRab1 is crucial for protein trafficking of the rhoptry secretory organelles, indicating a dual role in endocytic and exocytic protein trafficking. This study sets the stage for further dissecting endomembrane trafficking in Toxoplasma, along with potentially exploiting protein prenylation as a target for therapeutic development.
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Affiliation(s)
- Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
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2
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Piro F, Masci S, Kannan G, Focaia R, Schultz TL, Thaprawat P, Carruthers VB, Di Cristina M. A Toxoplasma gondii putative amino acid transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation. mSphere 2024; 9:e0059723. [PMID: 38051073 PMCID: PMC10871165 DOI: 10.1128/msphere.00597-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 10/26/2023] [Indexed: 12/07/2023] Open
Abstract
Toxoplasma gondii is a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. T. gondii possesses a lysosome-like organelle known as the plant-like vacuolar compartment (PLVAC), which serves various functions, including digestion, ion storage and homeostasis, endocytosis, and autophagy. Lysosomes are critical for maintaining cellular health and function by degrading waste materials and recycling components. To supply the cell with the essential building blocks and energy sources required for the maintenance of its functions and structures, the digested solutes generated within the lysosome are transported into the cytosol by proteins embedded in the lysosomal membrane. Currently, a limited number of PLVAC transporters have been characterized, with TgCRT being the sole potential transporter of amino acids and small peptides identified thus far. To bridge this knowledge gap, we used lysosomal amino acid transporters from other organisms as queries to search the T. gondii proteome. This led to the identification of four potential amino acid transporters, which we have designated as TgAAT1-4. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we present preliminary data showing the possible involvement of TgAAT1 in the PLVAC transport of arginine.IMPORTANCEToxoplasma gondii is a highly successful parasite infecting a broad range of warm-blooded organisms, including about one-third of all humans. Although Toxoplasma infections rarely result in symptomatic disease in individuals with a healthy immune system, the incredibly high number of persons infected, along with the risk of severe infection in immunocompromised patients and the potential link of chronic infection to mental disorders, makes this infection a significant public health concern. As a result, there is a pressing need for new treatment approaches that are both effective and well tolerated. The limitations in understanding how Toxoplasma gondii manages its metabolism to adapt to changing environments and triggers its transformation into bradyzoites have hindered the discovery of vulnerabilities in its metabolic pathways or nutrient acquisition mechanisms to identify new therapeutic targets. In this work, we have shown that the lysosome-like organelle plant-like vacuolar compartment (PLVAC), acting through the putative arginine transporter TgAAT1, plays a pivotal role in regulating the parasite's extracellular survival and differentiation into bradyzoites.
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Affiliation(s)
- Federica Piro
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Silvia Masci
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Riccardo Focaia
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Tracey L. Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Pariyamon Thaprawat
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
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Valleau D, Sidik SM, Godoy LC, Acevedo‐Sánchez Y, Pasaje CFA, Huynh M, Carruthers VB, Niles JC, Lourido S. A conserved complex of microneme proteins mediates rhoptry discharge in Toxoplasma. EMBO J 2023; 42:e113155. [PMID: 37886905 PMCID: PMC10690463 DOI: 10.15252/embj.2022113155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 09/19/2023] [Accepted: 09/25/2023] [Indexed: 10/28/2023] Open
Abstract
Apicomplexan parasites discharge specialized organelles called rhoptries upon host cell contact to mediate invasion. The events that drive rhoptry discharge are poorly understood, yet essential to sustain the apicomplexan parasitic life cycle. Rhoptry discharge appears to depend on proteins secreted from another set of organelles called micronemes, which vary in function from allowing host cell binding to facilitation of gliding motility. Here we examine the function of the microneme protein CLAMP, which we previously found to be necessary for Toxoplasma gondii host cell invasion, and demonstrate its essential role in rhoptry discharge. CLAMP forms a distinct complex with two other microneme proteins, the invasion-associated SPATR, and a previously uncharacterized protein we name CLAMP-linked invasion protein (CLIP). CLAMP deficiency does not impact parasite adhesion or microneme protein secretion; however, knockdown of any member of the CLAMP complex affects rhoptry discharge. Phylogenetic analysis suggests orthologs of the essential complex components, CLAMP and CLIP, are ubiquitous across apicomplexans. SPATR appears to act as an accessory factor in Toxoplasma, but despite incomplete conservation is also essential for invasion during Plasmodium falciparum blood stages. Together, our results reveal a new protein complex that mediates rhoptry discharge following host-cell contact.
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Affiliation(s)
| | | | - Luiz C Godoy
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | | | | | - My‐Hang Huynh
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Vern B Carruthers
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMIUSA
| | - Jacquin C Niles
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Sebastian Lourido
- Whitehead InstituteCambridgeMAUSA
- Biology DepartmentMassachusetts Institute of TechnologyCambridgeMAUSA
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4
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Wang F, Holmes MJ, Hong HJ, Thaprawat P, Kannan G, Huynh MH, Schultz TL, Licon MH, Lourido S, Sullivan WJ, O'Leary SE, Carruthers VB. Translation initiation factor eIF1.2 promotes Toxoplasma stage conversion by regulating levels of key differentiation factors. bioRxiv 2023:2023.11.03.565545. [PMID: 37961607 PMCID: PMC10635126 DOI: 10.1101/2023.11.03.565545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The parasite Toxoplasma gondii persists in its hosts by converting from replicating tachyzoites to latent bradyzoites housed in tissue cysts. The molecular mechanisms that mediate T. gondii differentiation remain poorly understood. Through a mutagenesis screen, we identified translation initiation factor eIF1.2 as a critical factor for T. gondii differentiation. A F97L mutation in eIF1.2 or the genetic ablation of eIF1.2 (Δ eIF1.2 ) markedly impeded bradyzoite cyst formation in vitro and in vivo . We demonstrated, at single-molecule level, that the eIF1.2 F97L mutation impacts the scanning process of the ribosome preinitiation complex on a model mRNA. RNA sequencing and ribosome profiling experiments unveiled that Δ eIF1.2 parasites are defective in the upregulating bradyzoite induction factors BFD1 and BFD2 during stress-induced differentiation. Forced expression of BFD1 or BFD2 significantly restored differentiation in Δ eIF1.2 parasites. Together, our findings suggest that eIF1.2 functions by regulating the translation of key differentiation factors necessary to establish chronic toxoplasmosis.
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Piro F, Masci S, Kannan G, Focaia R, Schultz TL, Carruthers VB, Di Cristina M. A Toxoplasma gondii putative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation. bioRxiv 2023:2023.08.31.555807. [PMID: 37693549 PMCID: PMC10491228 DOI: 10.1101/2023.08.31.555807] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Toxoplasma gondii is a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. Most eukaryotes, from yeast to mammals, rely on a nutrient sensing machinery involving the TORC complex as master regulator of cell growth and cell cycle progression. The lysosome functions as a signaling hub where TORC complex assembles and is activated by transceptors, which both sense and transport amino acids, including the arginine transceptor SLC38A9. While most of the TORC components are lost in T. gondii , indicating the evolution of a distinct nutrient sensing mechanism, the parasite's lysosomal plant-like vacuolar compartment (PLVAC) may still serve as a sensory platform for controlling parasite growth and differentiation. Using SLC38A9 to query the T. gondii proteome, we identified four putative amino acid transporters, termed TgAAT1-4, that structurally resemble the SLC38A9 arginine transceptor. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we show that TgAAT1 is involved in the PLVAC efflux of arginine, an amino acid playing a key role in T. gondii differentiation, further supporting the hypothesis that TgAAT1 might play a role in nutrient sensing. IMPORTANCE T. gondii is a highly successful parasite infecting a broad range of warm-blood organisms including about one third of all humans. Although Toxoplasma infections rarely result in symptomatic disease in individuals with a healthy immune system, the incredibly high number of persons infected along with the risk of severe infection in immunocompromised patients and the potential link of chronic infection to mental disorders make this infection a significant public health concern. As a result, there is a pressing need for new treatment approaches that are both effective and well-tolerated. The limitations in understanding how Toxoplasma gondii manages its metabolism to adapt to changing environments and triggers its transformation into bradyzoites have hindered the discovery of vulnerabilities in its metabolic pathways or nutrient acquisition mechanisms to identify new therapeutic targets. In this work, we have shown that the lysosome-like organelle PLVAC, acting through the putative arginine transporter TgAAT1, plays a pivotal role in regulating the parasite's extracellular survival and differentiation into bradyzoites.
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Aghabi D, Sloan M, Gill G, Hartmann E, Antipova O, Dou Z, Guerra AJ, Carruthers VB, Harding CR. The vacuolar iron transporter mediates iron detoxification in Toxoplasma gondii. Nat Commun 2023; 14:3659. [PMID: 37339985 DOI: 10.1038/s41467-023-39436-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 06/13/2023] [Indexed: 06/22/2023] Open
Abstract
Iron is essential to cells as a cofactor in enzymes of respiration and replication, however without correct storage, iron leads to the formation of dangerous oxygen radicals. In yeast and plants, iron is transported into a membrane-bound vacuole by the vacuolar iron transporter (VIT). This transporter is conserved in the apicomplexan family of obligate intracellular parasites, including in Toxoplasma gondii. Here, we assess the role of VIT and iron storage in T. gondii. By deleting VIT, we find a slight growth defect in vitro, and iron hypersensitivity, confirming its essential role in parasite iron detoxification, which can be rescued by scavenging of oxygen radicals. We show VIT expression is regulated by iron at transcript and protein levels, and by altering VIT localization. In the absence of VIT, T. gondii responds by altering expression of iron metabolism genes and by increasing antioxidant protein catalase activity. We also show that iron detoxification has an important role both in parasite survival within macrophages and in virulence in a mouse model. Together, by demonstrating a critical role for VIT during iron detoxification in T. gondii, we reveal the importance of iron storage in the parasite and provide the first insight into the machinery involved.
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Affiliation(s)
- Dana Aghabi
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Megan Sloan
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Grace Gill
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Elena Hartmann
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK
| | - Olga Antipova
- X-Ray Sciences Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - Alfredo J Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
- Cayman Chemical Company, Ann Arbor, MI, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA
| | - Clare R Harding
- Wellcome Centre of Integrative Parasitology, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
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Abstract
The Endosomal Sorting Complex Required for Transport (ESCRT) machinery consists of multiple protein complexes that coordinate vesicle budding away from the host cytosol. ESCRTs function in many fundamental cellular processes including the biogenesis of multivesicular bodies and exosomes, membrane repair and restoration, and cell abscission during cytokinesis. Work over the past 2 decades has shown that a diverse cohort of viruses critically rely upon host ESCRT machinery for virus replication and envelopment. More recent studies reported that intracellular bacteria and the intracellular parasite Toxoplasma gondii benefit from, antagonize, or exploit host ESCRT machinery to preserve their intracellular niche, gain resources, or egress from infected cells. Here, we review how intracellular pathogens interact with the ESCRT machinery of their hosts, highlighting the variety of strategies they use to bind ESCRT complexes using short linear amino acid motifs like those used by ESCRTs to sequentially assemble on target membranes. Future work exposing new mechanisms of this molecular mimicry will yield novel insight of how pathogens exploit host ESCRT machinery and how ESCRTs facilitate key cellular processes.
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Affiliation(s)
- Yolanda Rivera-Cuevas
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
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Koreny L, Mercado-Saavedra BN, Klinger CM, Barylyuk K, Butterworth S, Hirst J, Rivera-Cuevas Y, Zaccai NR, Holzer VJC, Klingl A, Dacks JB, Carruthers VB, Robinson MS, Gras S, Waller RF. Stable endocytic structures navigate the complex pellicle of apicomplexan parasites. Nat Commun 2023; 14:2167. [PMID: 37061511 PMCID: PMC10105704 DOI: 10.1038/s41467-023-37431-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 03/17/2023] [Indexed: 04/17/2023] Open
Abstract
Apicomplexan parasites have immense impacts on humanity, but their basic cellular processes are often poorly understood. Where endocytosis occurs in these cells, how conserved this process is with other eukaryotes, and what the functions of endocytosis are across this phylum are major unanswered questions. Using the apicomplexan model Toxoplasma, we identified the molecular composition and behavior of unusual, fixed endocytic structures. Here, stable complexes of endocytic proteins differ markedly from the dynamic assembly/disassembly of these machineries in other eukaryotes. We identify that these endocytic structures correspond to the 'micropore' that has been observed throughout the Apicomplexa. Moreover, conserved molecular adaptation of this structure is seen in apicomplexans including the kelch-domain protein K13 that is central to malarial drug-resistance. We determine that a dominant function of endocytosis in Toxoplasma is plasma membrane homeostasis, rather than parasite nutrition, and that these specialized endocytic structures originated early in infrakingdom Alveolata likely in response to the complex cell pellicle that defines this medically and ecologically important ancient eukaryotic lineage.
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Affiliation(s)
- Ludek Koreny
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | | | - Christen M Klinger
- Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2R3, Canada
| | | | - Simon Butterworth
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Yolanda Rivera-Cuevas
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Nathan R Zaccai
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Victoria J C Holzer
- Plant Development, Ludwig-Maximilians-University Munich, Planegg-Martinsried, 82152, Germany
| | - Andreas Klingl
- Plant Development, Ludwig-Maximilians-University Munich, Planegg-Martinsried, 82152, Germany
| | - Joel B Dacks
- Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2R3, Canada
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, 370 05, Czech Republic
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Simon Gras
- Experimental Parasitology, Department for Veterinary Sciences, Ludwig-Maximilians-University Munich, Planegg-Martinsried, 82152, Germany.
| | - Ross F Waller
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
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Romano PS, Akematsu T, Besteiro S, Bindschedler A, Carruthers VB, Chahine Z, Coppens I, Descoteaux A, Alberto Duque TL, He CY, Heussler V, Le Roch KG, Li FJ, de Menezes JPB, Menna-Barreto RFS, Mottram JC, Schmuckli-Maurer J, Turk B, Tavares Veras PS, Salassa BN, Vanrell MC. Autophagy in protists and their hosts: When, how and why? Autophagy Rep 2023; 2:2149211. [PMID: 37064813 PMCID: PMC10104450 DOI: 10.1080/27694127.2022.2149211] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 11/15/2022] [Indexed: 03/12/2023]
Abstract
Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.
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Affiliation(s)
- Patricia Silvia Romano
- Laboratorio de Biología de Trypanosoma cruzi y de la célula hospedadora. Instituto de Histología y Embriología de Mendoza. Universidad Nacional de Cuyo. (IHEM-CONICET-UNCUYO). Facultad de Ciencias Médicas. Universidad Nacional de Cuyo. Av. Libertador 80 (5500), Mendoza, Argentina
| | - Takahiko Akematsu
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | | | | | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Zeinab Chahine
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology. Department of Molecular Microbiology and Immunology. Johns Hopkins Malaria Research Institute. Johns Hopkins University Bloomberg School of Public Health. Baltimore 21205, MD, USA
| | - Albert Descoteaux
- Centre Armand-Frappier Santé Biotechnologie, Institut national de la recherche scientifique, Laval, QC
| | - Thabata Lopes Alberto Duque
- Autophagy Inflammation and Metabolism Center, University of New Mexico Health Sciences Center, Albuquerque, NM, USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Cynthia Y He
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Volker Heussler
- Institute of Cell Biology.University of Bern. Baltzerstr. 4 3012 Bern
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, CA, USA
| | - Feng-Jun Li
- Department of Biological Sciences, National University of Singapore, Singapore
| | | | | | - Jeremy C Mottram
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | | | - Boris Turk
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Patricia Sampaio Tavares Veras
- Laboratory of Host-Parasite Interaction and Epidemiology, Gonçalo Moniz Institute, Fiocruz-Bahia
- National Institute of Science and Technology of Tropical Diseases - National Council for Scientific Research and Development (CNPq)
| | - Betiana Nebai Salassa
- Laboratorio de Biología de Trypanosoma cruzi y de la célula hospedadora. Instituto de Histología y Embriología de Mendoza. Universidad Nacional de Cuyo. (IHEM-CONICET-UNCUYO). Facultad de Ciencias Médicas. Universidad Nacional de Cuyo. Av. Libertador 80 (5500), Mendoza, Argentina
| | - María Cristina Vanrell
- Laboratorio de Biología de Trypanosoma cruzi y de la célula hospedadora. Instituto de Histología y Embriología de Mendoza. Universidad Nacional de Cuyo. (IHEM-CONICET-UNCUYO). Facultad de Ciencias Médicas. Universidad Nacional de Cuyo. Av. Libertador 80 (5500), Mendoza, Argentina
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10
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Romano JD, Mayoral J, Guevara RB, Rivera-Cuevas Y, Carruthers VB, Weiss LM, Coppens I. Toxoplasma gondii scavenges mammalian host organelles through the usurpation of host ESCRT-III and Vps4A. J Cell Sci 2023; 136:jcs260159. [PMID: 36718630 PMCID: PMC10022688 DOI: 10.1242/jcs.260159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 01/19/2023] [Indexed: 02/01/2023] Open
Abstract
Intracellular pathogens exploit cellular resources through host cell manipulation. Within its nonfusogenic parasitophorous vacuole (PV), Toxoplasma gondii targets host nutrient-filled organelles and sequesters them into the PV through deep invaginations of the PV membrane (PVM) that ultimately detach from this membrane. Some of these invaginations are generated by an intravacuolar network (IVN) of parasite-derived tubules attached to the PVM. Here, we examined the usurpation of host ESCRT-III and Vps4A by the parasite to create PVM buds and vesicles. CHMP4B associated with the PVM/IVN, and dominant-negative (DN) CHMP4B formed many long PVM invaginations containing CHMP4B filaments. These invaginations were shorter in IVN-deficient parasites, suggesting cooperation between the IVN and ESCRT. In infected cells expressing Vps4A-DN, enlarged intra-PV structures containing host endolysosomes accumulated, reflecting defects in PVM scission. Parasite mutants lacking T. gondii (Tg)GRA14 or TgGRA64, which interact with ESCRT, reduced CHMP4B-DN-induced PVM invaginations and intra-PV host organelles, with greater defects in a double knockout, revealing the exploitation of ESCRT to scavenge host organelles by Toxoplasma.
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Affiliation(s)
- Julia D. Romano
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Joshua Mayoral
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Rebekah B. Guevara
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yolanda Rivera-Cuevas
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
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11
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Smith D, Lunghi M, Olafsson EB, Hatton O, Di Cristina M, Carruthers VB. A High-Throughput Amenable Dual Luciferase System for Measuring Toxoplasma gondii Bradyzoite Viability after Drug Treatment. Anal Chem 2023; 95:668-676. [PMID: 36548400 PMCID: PMC9850410 DOI: 10.1021/acs.analchem.2c02174] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
It is estimated that more than 2 billion people are chronically infected with the intracellular protozoan parasite Toxoplasma gondii (T. gondii). Despite this, there is currently no vaccine to prevent infection in humans, and there is no recognized curative treatment to clear tissue cysts. A major hurdle for identifying effective drug candidates against chronic-stage cysts has been the low throughput of existing in vitro assays for testing the survival of bradyzoites. We have developed a luciferase-based platform for specifically determining bradyzoite survival within in vitro cysts in a 96-well plate format. We engineered a cystogenic type II T. gondii PruΔku80Δhxgpr strain for stage-specific expression of firefly luciferase in the cytosol of bradyzoites and nanoluciferase for secretion into the lumen of the cyst (DuaLuc strain). Using this DuaLuc strain, we found that the ratio of firefly luciferase to nanoluciferase decreased upon treatment with atovaquone or LHVS, two compounds that are known to compromise bradyzoite viability. The 96-well format allowed us to test several additional compounds and generate dose-response curves for calculation of EC50 values indicating relative effectiveness of a compound. Accordingly, this DuaLuc system should be suitable for screening libraries of diverse compounds and defining the potency of hits or other compounds with a putative antibradyzoite activity.
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Affiliation(s)
- David Smith
- University of Michigan Medical School, Ann Arbor 734 763 2081, United States
- Moredun Research Institute, Penicuik EH26 0PZ, U.K.
| | - Matteo Lunghi
- Università degli Studi di Perugia, Perugia 06123, Italy
| | - Einar B. Olafsson
- University of Michigan Medical School, Ann Arbor 734 763 2081, United States
- University of Uppsala, Uppsala 751 05, Sweden
| | - Olivia Hatton
- University of Michigan Medical School, Ann Arbor 734 763 2081, United States
| | | | - Vern B. Carruthers
- University of Michigan Medical School, Ann Arbor 734 763 2081, United States
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12
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Stasic AJ, Moreno SNJ, Carruthers VB, Dou Z. The Toxoplasma plant-like vacuolar compartment (PLVAC). J Eukaryot Microbiol 2022; 69:e12951. [PMID: 36218001 PMCID: PMC10576567 DOI: 10.1111/jeu.12951] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/28/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. T. gondii shares several characteristics with plants including a nonphotosynthetic plastid termed apicoplast and a multivesicular organelle that was named the plant-like vacuole (PLV) or vacuolar compartment (VAC). The name plant-like vacuole was selected based on its resemblance in composition and function to plant vacuoles. The name VAC represents its general vacuolar characteristics. We will refer to the organelle as PLVAC in this review. New findings in recent years have revealed that the PLVAC represents the lysosomal compartment of T. gondii which has adapted peculiarities to fulfill specific Toxoplasma needs. In this review, we discuss the composition and functions of the PLVAC highlighting its roles in ion storage and homeostasis, endocytosis, exocytosis, and autophagy.
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Affiliation(s)
- Andrew J Stasic
- Department of Microbiology, Heartland FPG, Carmel, Indiana, USA
| | - Silvia N J Moreno
- Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
| | - Vern B Carruthers
- Department of Microbiology & Immunology, University of Michigan Medical School, Michigan, Ann Arbor, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, South Carolina, Clemson, USA
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13
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Bahwal SA, Chen JJ, E L, Hao T, Chen J, Carruthers VB, Lai J, Zhou X. Attenuated Toxoplasma gondii enhances the antitumor efficacy of anti-PD1 antibody by altering the tumor microenvironment in a pancreatic cancer mouse model. J Cancer Res Clin Oncol 2022; 148:2743-2757. [PMID: 35556163 DOI: 10.1007/s00432-022-04036-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/19/2022] [Indexed: 01/05/2023]
Abstract
PURPOSE To investigate whether attenuated Toxoplasma is efficacious against solid tumors of pancreatic cancer and whether attenuated Toxoplasma improves the antitumor activity of αPD-1 antibody on pancreatic cancer. METHODS The therapeutic effects of attenuated Toxoplasma NRTUA strain monotherapy and combination therapy of NRTUA with anti-PD-1 antibody on PDAC tumor volume and tumor weight of Pan02 tumor-bearing mice were investigated. We characterized the effects of combination therapy of NRTUA with anti-PD-1 antibody on tumor-infiltrating lymphocytes and tumor-specific IFN-γ by using immunohistochemistry, flow cytometry and ELISA. The antitumor mechanisms of combination therapy of NRTUA with anti-PD-1 antibody were investigated via depletion of CD8+ T cells and IL-12. RESULTS NRTUA strain treatment inhibited tumor growth in a subcutaneous mouse model of PDAC through activating dendritic cells and increasing CD8+ T cell infiltration in the tumor microenvironment. More importantly, combination therapy of NRTUA with anti-PD-1 antibody elicited a significant antitumor immune response and synergistically controlled tumor growth in Pan02 tumor-bearing mice. Specifically, the combination treatment led to elevation of CD8+ T cell infiltration mediated by dendritic cell-secreted IL-12 and to tumor-specific IFN-γ production in the PDAC tumor microenvironment. Also, the combination treatment markedly reduced the immunosuppressive myeloid-derived suppressor cell population in PDAC mice. CONCLUSION These findings could provide a novel immunotherapy approach to treating solid tumors of PDAC and overcoming resistance to anti-PD-1 agents in PDAC tumors.
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Affiliation(s)
- Said Ahmed Bahwal
- Department of Biochemistry and Molecular Biology, Sun Yat-Sen University Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Jane J Chen
- Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Lilin E
- Department of Biochemistry and Molecular Biology, Sun Yat-Sen University Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Taofang Hao
- Department of Biochemistry and Molecular Biology, Sun Yat-Sen University Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Jiancong Chen
- Department of Pancreato-Biliary Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, MI, 48109-5620, USA.
| | - Jiaming Lai
- Department of Pancreato-Biliary Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China.
| | - Xingwang Zhou
- Department of Biochemistry and Molecular Biology, Sun Yat-Sen University Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China.
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14
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Huynh MH, Carruthers VB. Toxoplasma gondii excretion of glycolytic products is associated with acidification of the parasitophorous vacuole during parasite egress. PLoS Pathog 2022; 18:e1010139. [PMID: 35512005 PMCID: PMC9113570 DOI: 10.1371/journal.ppat.1010139] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 05/17/2022] [Accepted: 03/28/2022] [Indexed: 11/19/2022] Open
Abstract
The Toxoplasma gondii lytic cycle is a repetition of host cell invasion, replication, egress, and re-invasion into the next host cell. While the molecular players involved in egress have been studied in greater detail in recent years, the signals and pathways for triggering egress from the host cell have not been fully elucidated. A perforin-like protein, PLP1, has been shown to be necessary for permeabilizing the parasitophorous vacuole (PV) membrane or exit from the host cell. In vitro studies indicated that PLP1 is most active in acidic conditions, and indirect evidence using superecliptic pHluorin indicated that the PV pH drops prior to parasite egress. Using ratiometric pHluorin, a GFP variant that responds to changes in pH with changes in its bimodal excitation spectrum peaks, allowed us to directly measure the pH in the PV prior to and during egress by live-imaging microscopy. A statistically significant change was observed in PV pH during ionomycin or zaprinast induced egress in both wild-type RH and Δplp1 vacuoles compared to DMSO-treated vacuoles. Interestingly, if parasites are chemically paralyzed, a pH drop is still observed in RH but not in Δplp1 tachyzoites. This indicates that the pH drop is dependent on the presence of PLP1 or motility. Efforts to determine transporters, exchangers, or pumps that could contribute to the drop in PV pH identified two formate-nitrite transporters (FNTs). Auxin induced conditional knockdown and knockouts of FNT1 and FNT2 reduced the levels of lactate and pyruvate released by the parasites and lead to an abatement of vacuolar acidification. While additional transporters and molecules are undoubtedly involved, we provide evidence of a definitive reduction in vacuolar pH associated with induced and natural egress and characterize two transporters that contribute to the acidification. Toxoplasma gondii is a single celled intracellular parasite that infects many different animals, and it is thought to infect up to one third of the human population. This parasite must rupture out of its replicative compartment and the host cell to spread from one cell to another. Previous studies indicated that a decrease in pH occurs within the replicative compartment near the time of parasite exit from host cells, an event termed egress. However, it remained unknown whether the decrease in pH is directly tied to egress and, if so, what is responsible for the decrease in pH. Here we used a fluorescent reporter protein to directly measure pH within the replicative compartment during parasite egress. We found that pH decreases immediately prior to parasite egress and that this decrease is linked to parasite disruption of membranes. We also identified a family of transporters that release acidic products from parasite use of glucose for energy as contributing to the decrease in pH during egress. Our findings provide new insight that connects parasite glucose metabolism to acidification of its replicative compartment during egress from infected cells.
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Affiliation(s)
- My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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15
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Rivera-Cuevas Y, Mayoral J, Di Cristina M, Lawrence ALE, Olafsson EB, Patel RK, Thornhill D, Waldman BS, Ono A, Sexton JZ, Lourido S, Weiss LM, Carruthers VB. Toxoplasma gondii exploits the host ESCRT machinery for parasite uptake of host cytosolic proteins. PLoS Pathog 2021; 17:e1010138. [PMID: 34898650 PMCID: PMC8700025 DOI: 10.1371/journal.ppat.1010138] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [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: 07/28/2021] [Revised: 12/23/2021] [Accepted: 11/23/2021] [Indexed: 11/18/2022] Open
Abstract
Toxoplasma gondii is a master manipulator capable of effectively siphoning the resources from the host cell for its intracellular subsistence. However, the molecular underpinnings of how the parasite gains resources from its host remain largely unknown. Residing within a non-fusogenic parasitophorous vacuole (PV), the parasite must acquire resources across the limiting membrane of its replicative niche, which is decorated with parasite proteins including those secreted from dense granules. We discovered a role for the host Endosomal Sorting Complex Required for Transport (ESCRT) machinery in host cytosolic protein uptake by T. gondii by disrupting host ESCRT function. We identified the transmembrane dense granule protein TgGRA14, which contains motifs homologous to the late domain motifs of HIV-1 Gag, as a candidate for the recruitment of the host ESCRT machinery to the PV membrane. Using an HIV-1 virus-like particle (VLP) release assay, we found that the motif-containing portion of TgGRA14 is sufficient to substitute for HIV-1 Gag late domain to mediate ESCRT-dependent VLP budding. We also show that TgGRA14 is proximal to and interacts with host ESCRT components and other dense granule proteins during infection. Furthermore, analysis of TgGRA14-deficient parasites revealed a marked reduction in ingestion of a host cytosolic protein compared to WT parasites. Thus, we propose a model in which T. gondii recruits the host ESCRT machinery to the PV where it can interact with TgGRA14 for the internalization of host cytosolic proteins across the PV membrane (PVM). These findings provide new insight into how T. gondii accesses contents of the host cytosol by exploiting a key pathway for vesicular budding and membrane scission.
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Affiliation(s)
- Yolanda Rivera-Cuevas
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Joshua Mayoral
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Anna-Lisa E. Lawrence
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Einar B. Olafsson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Romir K. Patel
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Dishari Thornhill
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Benjamin S. Waldman
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Jonathan Z. Sexton
- Department of Medicinal Chemistry, College of Pharmacy, Ann Arbor, Michigan, United States of America
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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16
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Huynh MH, Roiko MS, Gomes AO, Schinke EN, Schultz AJ, Agrawal S, Oellig CA, Sexton TR, Beauchamp JM, Laliberté J, Sivaraman KK, Hersh LB, McGowan S, Carruthers VB. Toxoplasma gondii Toxolysin 4 Contributes to Efficient Parasite Egress from Host Cells. mSphere 2021; 6:e0044421. [PMID: 34190588 PMCID: PMC8265663 DOI: 10.1128/msphere.00444-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/09/2021] [Indexed: 11/24/2022] Open
Abstract
Egress from host cells is an essential step in the lytic cycle of T. gondii and other apicomplexan parasites; however, only a few parasite secretory proteins are known to affect this process. The putative metalloproteinase toxolysin 4 (TLN4) was previously shown to be an extensively processed microneme protein, but further characterization was impeded by the inability to genetically ablate TLN4. Here, we show that TLN4 has the structural properties of an M16 family metalloproteinase, that it possesses proteolytic activity on a model substrate, and that genetic disruption of TLN4 reduces the efficiency of egress from host cells. Complementation of the knockout strain with the TLN4 coding sequence significantly restored egress competency, affirming that the phenotype of the Δtln4 parasite was due to the absence of TLN4. This work identifies TLN4 as the first metalloproteinase and the second microneme protein to function in T. gondii egress. The study also lays a foundation for future mechanistic studies defining the precise role of TLN4 in parasite exit from host cells. IMPORTANCE After replicating within infected host cells, the single-celled parasite Toxoplasma gondii must rupture out of such cells in a process termed egress. Although it is known that T. gondii egress is an active event that involves disruption of host-derived membranes surrounding the parasite, very few proteins that are released by the parasite are known to facilitate egress. In this study, we identify a parasite secretory protease that is necessary for efficient and timely egress, laying the foundation for understanding precisely how this protease facilitates T. gondii exit from host cells.
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Affiliation(s)
- My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Marijo S. Roiko
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Angelica O. Gomes
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ellyn N. Schinke
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Aric J. Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Swati Agrawal
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Christine A. Oellig
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Travis R. Sexton
- Department of Cardiology, University of Kentucky, Lexington, Kentucky, USA
| | - Jessica M. Beauchamp
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julie Laliberté
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Komagal Kannan Sivaraman
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Louis B. Hersh
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Sheena McGowan
- Infection and Immunity Program, Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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17
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Smith D, Kannan G, Coppens I, Wang F, Nguyen HM, Cerutti A, Olafsson EB, Rimple PA, Schultz TL, Mercado Soto NM, Di Cristina M, Besteiro S, Carruthers VB. Toxoplasma TgATG9 is critical for autophagy and long-term persistence in tissue cysts. eLife 2021; 10:e59384. [PMID: 33904393 PMCID: PMC8128441 DOI: 10.7554/elife.59384] [Citation(s) in RCA: 18] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 04/27/2021] [Indexed: 12/29/2022] Open
Abstract
Many of the world's warm-blooded species are chronically infected with Toxoplasma gondii tissue cysts, including an estimated one-third of the global human population. The cellular processes that permit long-term persistence within the cyst are largely unknown for T. gondii and related coccidian parasites that impact human and animal health. Herein, we show that genetic ablation of TgATG9 substantially reduces canonical autophagy and compromises bradyzoite viability. Transmission electron microscopy revealed numerous structural abnormalities occurring in ∆atg9 bradyzoites. Intriguingly, abnormal mitochondrial networks were observed in TgATG9-deficient bradyzoites, some of which contained numerous different cytoplasmic components and organelles. ∆atg9 bradyzoite fitness was drastically compromised in vitro and in mice, with very few brain cysts identified in mice 5 weeks post-infection. Taken together, our data suggests that TgATG9, and by extension autophagy, is critical for cellular homeostasis in bradyzoites and is necessary for long-term persistence within the cyst of this coccidian parasite.
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Affiliation(s)
- David Smith
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Fengrong Wang
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Hoa Mai Nguyen
- Laboratory of PathogenHost Interactions, UMR 5235, CNRS, Université de MontpellierMontpellierFrance
| | - Aude Cerutti
- Laboratory of PathogenHost Interactions, UMR 5235, CNRS, Université de MontpellierMontpellierFrance
| | - Einar B Olafsson
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Patrick A Rimple
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Nayanna M Mercado Soto
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
| | - Manlio Di Cristina
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
- Department of Chemistry, Biology and Biotechnology, Università degli Studi di PerugiaPerugiaItaly
| | - Sébastien Besteiro
- Laboratory of PathogenHost Interactions, UMR 5235, CNRS, Université de MontpellierMontpellierFrance
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn ArborUnited States
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Steinberg HE, Bowman NM, Diestra A, Ferradas C, Russo P, Clark DE, Zhu D, Magni R, Malaga E, Diaz M, Pinedo-Cancino V, Ramal Asayag C, Calderón M, Carruthers VB, Liotta LA, Gilman RH, Luchini A. Detection of toxoplasmic encephalitis in HIV positive patients in urine with hydrogel nanoparticles. PLoS Negl Trop Dis 2021; 15:e0009199. [PMID: 33651824 PMCID: PMC7954332 DOI: 10.1371/journal.pntd.0009199] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 03/12/2021] [Accepted: 02/02/2021] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Diagnosis of toxoplasmic encephalitis (TE) is challenging under the best clinical circumstances. The poor clinical sensitivity of quantitative polymerase chain reaction (qPCR) for Toxoplasma in blood and CSF and the limited availability of molecular diagnostics and imaging technology leaves clinicians in resource-limited settings with few options other than empiric treatment. METHOLOGY/PRINCIPLE FINDINGS Here we describe proof of concept for a novel urine diagnostics for TE using Poly-N-Isopropylacrylamide nanoparticles dyed with Reactive Blue-221 to concentrate antigens, substantially increasing the limit of detection. After nanoparticle-concentration, a standard western blotting technique with a monoclonal antibody was used for antigen detection. Limit of detection was 7.8pg/ml and 31.3pg/ml of T. gondii antigens GRA1 and SAG1, respectively. To characterize this diagnostic approach, 164 hospitalized HIV-infected patients with neurological symptoms compatible with TE were tested for 1) T. gondii serology (121/147, positive samples/total samples tested), 2) qPCR in cerebrospinal fluid (11/41), 3) qPCR in blood (10/112), and 4) urinary GRA1 (30/164) and SAG1 (12/164). GRA1 appears to be superior to SAG1 for detection of TE antigens in urine. Fifty-one HIV-infected, T. gondii seropositive but asymptomatic persons all tested negative by nanoparticle western blot and blood qPCR, suggesting the test has good specificity for TE for both GRA1 and SAG1. In a subgroup of 44 patients, urine samples were assayed with mass spectrometry parallel-reaction-monitoring (PRM) for the presence of T. gondii antigens. PRM identified antigens in 8 samples, 6 of which were concordant with the urine diagnostic. CONCLUSION/SIGNIFICANCES Our results demonstrate nanoparticle technology's potential for a noninvasive diagnostic test for TE. Moving forward, GRA1 is a promising target for antigen based diagnostics for TE.
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Affiliation(s)
- Hannah E. Steinberg
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, United States of America
| | - Natalie M. Bowman
- Division of Infectious Disease, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Andrea Diestra
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Cusi Ferradas
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Paul Russo
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Virginia, United States of America
| | - Daniel E. Clark
- Vanderbilt University Medical Center, Division of Cardiovascular Medicine, Nashville, Tennessee, United States of America
| | - Deanna Zhu
- Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Ruben Magni
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Virginia, United States of America
| | - Edith Malaga
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Monica Diaz
- Department of Neurology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Viviana Pinedo-Cancino
- Laboratorio de Investigación de Productos Naturales Antiparasitarios de la Amazonía, Facultad de Medicina Humana, Universidad Nacional de la Amazonía Peruana, Iquitos, Peru
| | - Cesar Ramal Asayag
- Universidad Nacional de la Amazonía Peruana, Iquitos, Peru
- Department of Infectious Diseases, Hospital Regional de Loreto, Iquitos, Peru
| | - Maritza Calderón
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Virginia, United States of America
| | - Robert H. Gilman
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Alessandra Luchini
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Virginia, United States of America
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Abstract
Toxoplasma gondii is a protozoan parasite that persists in the central nervous system as intracellular chronic-stage bradyzoites that are encapsulated by a thick cyst wall. While the cyst wall separates bradyzoites from the host cytosol, it has been posited that small solutes can traverse the cyst wall to sustain bradyzoites. Recently, it was found that host cytosolic macromolecules can cross the parasitophorous vacuole and are ingested and digested by actively replicating acute-stage tachyzoites. However, the extent to which bradyzoites have an active ingestion pathway remained unknown. To interrogate this, we modified previously published protocols that look at tachyzoite acquisition and digestion of host proteins by measuring parasite accumulation of a host-expressed reporter protein after impairment of an endolysosomal protease (cathepsin protease L [CPL]). Using two cystogenic parasite strains (ME49 and Pru), we demonstrate that T. gondii bradyzoites can ingest host-derived cytosolic mCherry. Bradyzoites acquire host mCherry within 4 h of invasion and after cyst wall formation. This study provides direct evidence that host macromolecules can be internalized by T. gondii bradyzoites across the cyst wall in infected cells.IMPORTANCE Chronic infection of humans with Toxoplasma gondii is common, but little is known about how this intracellular parasite obtains the resources that it needs to persist indefinitely inside neurons and muscle cells. Here, we provide evidence that the chronic-stage form of T. gondii can internalize proteins from the cytosol of infected cells despite residing within an intracellular cyst that is surrounded by a cyst wall. We also show that accumulation of host-derived protein within the chronic-stage parasites is enhanced by disruption of a parasite protease, suggesting that such protein is normally degraded to generate peptides and amino acids. Taken together, our findings imply that chronic-stage T. gondii can ingest and digest host proteins, potentially to support its persistence.
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Affiliation(s)
- Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Pariyamon Thaprawat
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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20
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McGovern OL, Rivera-Cuevas Y, Carruthers VB. Emerging Mechanisms of Endocytosis in Toxoplasma gondii. Life (Basel) 2021; 11:life11020084. [PMID: 33503859 PMCID: PMC7911406 DOI: 10.3390/life11020084] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Eukaryotes critically rely on endocytosis of autologous and heterologous material to maintain homeostasis and to proliferate. Although mechanisms of endocytosis have been extensively identified in mammalian and plant systems along with model systems including budding yeast, relatively little is known about endocytosis in protozoan parasites including those belonging to the phylum Apicomplexa. Whereas it has been long established that the apicomplexan agents of malaria (Plasmodium spp.) internalize and degrade hemoglobin from infected red blood cells to acquire amino acids for growth, that the related and pervasive parasite Toxoplasma gondii has a functional and active endocytic system was only recently discovered. Here we discuss emerging and hypothesized mechanisms of endocytosis in Toxoplasma gondii with reference to model systems and malaria parasites. Establishing a framework for potential mechanisms of endocytosis in Toxoplasma gondii will help guide future research aimed at defining the molecular basis and biological relevance of endocytosis in this tractable and versatile parasite.
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21
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Young JC, Broncel M, Teague H, Russell MRG, McGovern OL, Renshaw M, Frith D, Snijders AP, Collinson L, Carruthers VB, Ewald SE, Treeck M. Phosphorylation of Toxoplasma gondii Secreted Proteins during Acute and Chronic Stages of Infection. mSphere 2020; 5:e00792-20. [PMID: 32907954 PMCID: PMC7485689 DOI: 10.1128/msphere.00792-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 01/07/2023] Open
Abstract
The intracellular parasite Toxoplasma gondii resides within a membrane-bound parasitophorous vacuole (PV) and secretes an array of proteins to establish this replicative niche. It has been shown previously that Toxoplasma secretes kinases and that numerous proteins are phosphorylated after secretion. Here, we assess the role of the phosphorylation of strand-forming protein 1 (SFP1) and the related protein GRA29, two secreted proteins with unknown function. We show that both proteins form stranded structures in the PV that are independent of the previously described intravacuolar network or actin. SFP1 and GRA29 can each form these structures independently of other Toxoplasma secreted proteins, although GRA29 appears to regulate SFP1 strands. We show that an unstructured region at the C termini of SFP1 and GRA29 is required for the formation of strands and that mimicking the phosphorylation of this domain of SFP1 negatively regulates strand development. When tachyzoites convert to chronic-stage bradyzoites, both proteins show a dispersed localization throughout the cyst matrix. Many secreted proteins are reported to dynamically redistribute as the cyst forms, and secreted kinases are known to play a role in cyst formation. Using quantitative phosphoproteome and proteome analyses comparing tachyzoite and early bradyzoite stages, we reveal widespread differential phosphorylation of secreted proteins. While we found no direct evidence for phosphorylation playing a dominant role for SFP1/GRA29 redistribution in the cyst, these data support a model in which secreted kinases and phosphatases contribute to the regulation of secreted proteins during stage conversion.IMPORTANCEToxoplasma gondii is a common parasite that infects up to one-third of the human population. Initially, the parasite grows rapidly, infecting and destroying cells of the host, but subsequently switches to a slow-growing form and establishes chronic infection. In both stages, the parasite lives within a membrane-bound vacuole within the host cell, but in the chronic stage, a durable cyst wall is synthesized, which provides protection to the parasite during transmission to a new host. Toxoplasma secretes proteins into the vacuole to build its replicative niche, and previous studies identified many of these proteins as phosphorylated. We investigate two secreted proteins and show that a phosphorylated region plays an important role in their regulation in acute stages. We also observed widespread phosphorylation of secreted proteins when parasites convert from acute to chronic stages, providing new insight into how the cyst wall may be dynamically regulated.
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Affiliation(s)
- Joanna C Young
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Malgorzata Broncel
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Helena Teague
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Matt R G Russell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Olivia L McGovern
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Matt Renshaw
- Advanced Light Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - David Frith
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Ambrosius P Snijders
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Lucy Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sarah E Ewald
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
- Carter Immunology Center, University of Virginia, Charlottesville, Virginia, USA
| | - Moritz Treeck
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
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22
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Zwicker JD, Smith D, Guerra AJ, Hitchens JR, Haug N, Vander Roest S, Lee P, Wen B, Sun D, Wang L, Keep RF, Xiang J, Carruthers VB, Larsen SD. Discovery and Optimization of Triazine Nitrile Inhibitors of Toxoplasma gondii Cathepsin L for the Potential Treatment of Chronic Toxoplasmosis in the CNS. ACS Chem Neurosci 2020; 11:2450-2463. [PMID: 32027110 DOI: 10.1021/acschemneuro.9b00674] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
With roughly 2 billion people infected, the neurotropic protozoan Toxoplasma gondii remains one of the most pervasive and infectious parasites. Toxoplasma infection is the second leading cause of death due to foodborne illness in the United States, causes severe disease in immunocompromised patients, and is correlated with several cognitive and neurological disorders. Currently, no therapies exist that are capable of eliminating the persistent infection in the central nervous system (CNS). In this study we report the identification of triazine nitrile inhibitors of Toxoplasma cathepsin L (TgCPL) from a high throughput screen and their subsequent optimization. Through rational design, we improved inhibitor potency to as low as 5 nM, identified pharmacophore features that can be exploited for isoform selectivity (up to 7-fold for TgCPL versus human isoform), and improved metabolic stability (t1/2 > 60 min in mouse liver microsomes) guided by a metabolite ID study. We demonstrated that this class of compounds is capable of crossing the blood-brain barrier in mice (1:1 brain/plasma at 2 h). Importantly, we also show for the first time that treatment of T. gondii bradyzoite cysts in vitro with triazine nitrile inhibitors reduces parasite viability with efficacy equivalent to a TgCPL genetic knockout.
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Affiliation(s)
- Jeffery D. Zwicker
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - David Smith
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Alfredo J. Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jacob R. Hitchens
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nicole Haug
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Steve Vander Roest
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Pil Lee
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bo Wen
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Duxin Sun
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lu Wang
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Richard F. Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jianming Xiang
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Scott D. Larsen
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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23
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Kannan G, Di Cristina M, Schultz AJ, Huynh MH, Wang F, Schultz TL, Lunghi M, Coppens I, Carruthers VB. Role of Toxoplasma gondii Chloroquine Resistance Transporter in Bradyzoite Viability and Digestive Vacuole Maintenance. mBio 2019; 10:e01324-19. [PMID: 31387907 PMCID: PMC6686041 DOI: 10.1128/mbio.01324-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 05/21/2019] [Accepted: 07/12/2019] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is a ubiquitous pathogen that can cause encephalitis, congenital defects, and ocular disease. T. gondii has also been implicated as a risk factor for mental illness in humans. The parasite persists in the brain as slow-growing bradyzoites contained within intracellular cysts. No treatments exist to eliminate this form of parasite. Although proteolytic degradation within the parasite lysosome-like vacuolar compartment (VAC) is critical for bradyzoite viability, whether other aspects of the VAC are important for parasite persistence remains unknown. An ortholog of Plasmodium falciparum chloroquine resistance transporter (CRT), TgCRT, has previously been identified in T. gondii To interrogate the function of TgCRT in chronic-stage bradyzoites and its role in persistence, we knocked out TgCRT in a cystogenic strain and assessed VAC size, VAC digestion of host-derived proteins and parasite autophagosomes, and the viability of in vitro and in vivo bradyzoites. We found that whereas parasites deficient in TgCRT exhibit normal digestion within the VAC, they display a markedly distended VAC and their viability is compromised both in vitro and in vivo Interestingly, impairing VAC proteolysis in TgCRT-deficient bradyzoites restored VAC size, consistent with a role for TgCRT as a transporter of products of digestion from the VAC. In conjunction with earlier studies, our current findings suggest a functional link between TgCRT and VAC proteolysis. This study provides further evidence of a crucial role for the VAC in bradyzoite persistence and a new potential VAC target to abate chronic Toxoplasma infection.IMPORTANCE Individuals chronically infected with the intracellular parasite Toxoplasma gondii are at risk of experiencing reactivated disease that can result in progressive loss of vision. No effective treatments exist for chronic toxoplasmosis due in part to a poor understanding of the biology underlying chronic infection and a lack of well-validated potential targets. We show here that a T. gondii transporter is functionally linked to protein digestion within the parasite lysosome-like organelle and that this transporter is necessary to sustain chronic infection in culture and in experimentally infected mice. Ablating the transporter results in severe bloating of the lysosome-like organelle. Together with earlier work, this study suggests the parasite's lysosome-like organelle is vital for parasite survival, thus rendering it a potential target for diminishing infection and reducing the risk of reactivated disease.
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Affiliation(s)
- Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Aric J Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Fengrong Wang
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Matteo Lunghi
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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24
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Abstract
Although many cellular components of the Ca2+ signaling pathway dictating Toxoplasma gondii egress have been identified, whether the parasite secretes protein activators of this pathway remained unknown. Bisio et al. (Nat. Microbiol. 2019;4:420-428) identify a parasite-secreted diacylglycerol kinase as a key upstream activator of signaling for 'programmed' egress from host cells.
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Affiliation(s)
- Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5620, USA.
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25
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Guerra AJ, Zhang O, Bahr CME, Huynh MH, DelProposto J, Brown WC, Wawrzak Z, Koropatkin NM, Carruthers VB. Structural basis of Toxoplasma gondii perforin-like protein 1 membrane interaction and activity during egress. PLoS Pathog 2018; 14:e1007476. [PMID: 30513119 PMCID: PMC6294395 DOI: 10.1371/journal.ppat.1007476] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 12/14/2018] [Accepted: 11/19/2018] [Indexed: 11/19/2022] Open
Abstract
Intracellular pathogens must egress from the host cell to continue their infectious cycle. Apicomplexans are a phylum of intracellular protozoans that have evolved members of the membrane attack complex and perforin (MACPF) family of pore forming proteins to disrupt cellular membranes for traversing cells during tissue migration or egress from a replicative vacuole following intracellular reproduction. Previous work showed that the apicomplexan Toxoplasma gondii secretes a perforin-like protein (TgPLP1) that contains a C-terminal Domain (CTD) which is necessary for efficient parasite egress. However, the structural basis for CTD membrane binding and egress competency remained unknown. Here, we present evidence that TgPLP1 CTD prefers binding lipids that are abundant in the inner leaflet of the lipid bilayer. Additionally, solving the high-resolution crystal structure of the TgPLP1 APCβ domain within the CTD reveals an unusual double-layered β-prism fold that resembles only one other protein of known structure. Three direct repeat sequences comprise subdomains, with each constituting a wall of the β-prism fold. One subdomain features a protruding hydrophobic loop with an exposed tryptophan at its tip. Spectrophotometric measurements of intrinsic tryptophan fluorescence are consistent with insertion of the hydrophobic loop into a target membrane. Using CRISPR/Cas9 gene editing we show that parasite strains bearing mutations in the hydrophobic loop, including alanine substitution of the tip tryptophan, are equally deficient in egress as a strain lacking TgPLP1 altogether. Taken together our findings suggest a crucial role for the hydrophobic loop in anchoring TgPLP1 to the membrane to support its cytolytic activity and egress function. The intracellular parasite Toxoplasma gondii infects many hosts including humans. Infected people with a weak immune system can suffer severe disease when the parasite replicates uncontrolled via repeated cycles of cell invasion, intracellular growth, and exit, resulting in cell death. Previous studies showed that T. gondii encodes a pore-forming protein, TgPLP1, which contains an unusual domain that is crucial for efficient exit from both the parasite containing vacuole and the host cell. However, how TgPLP1 recognizes and binds to the appropriate membrane is unclear. Here we use a combination of biochemistry, structural biology, and parasitology to identify a preference of TgPLP1 for specific lipids and show that a loop within the structure of the membrane-binding domain inserts into the target membrane and is necessary for exit from the parasite containing vacuole. Our study sheds light into the determinants of membrane binding in TgPLP1 and may inform the overall mechanism of pore formation in similar systems.
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Affiliation(s)
- Alfredo J. Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
- * E-mail:
| | - Ou Zhang
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
| | - Constance M. E. Bahr
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
| | - James DelProposto
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - William C. Brown
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Zdzislaw Wawrzak
- Northwestern Synchrotron Research Center–LS-CAT, Northwestern University, Argonne, IL, United States of America
| | - Nicole M. Koropatkin
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, United States of America
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26
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Khurana S, Coffey MJ, John A, Uboldi AD, Huynh MH, Stewart RJ, Carruthers VB, Tonkin CJ, Goddard-Borger ED, Scott NE. Protein O-fucosyltransferase 2-mediated O-glycosylation of the adhesin MIC2 is dispensable for Toxoplasma gondii tachyzoite infection. J Biol Chem 2018; 294:1541-1553. [PMID: 30514763 DOI: 10.1074/jbc.ra118.005357] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
Toxoplasma gondii is a ubiquitous, obligate intracellular eukaryotic parasite that causes congenital birth defects, disease in immunocompromised individuals, and blindness. Protein glycosylation plays an important role in the infectivity and evasion of immune responses of many eukaryotic parasites and is also of great relevance to vaccine design. Here we demonstrate that micronemal protein 2 (MIC2), a motility-associated adhesin of T. gondii, has highly glycosylated thrombospondin repeat (TSR) domains. Using affinity-purified MIC2 and MS/MS analysis along with enzymatic digestion assays, we observed that at least seven C-linked and three O-linked glycosylation sites exist within MIC2, with >95% occupancy at these O-glycosylation sites. We found that addition of O-glycans to MIC2 is mediated by a protein O-fucosyltransferase 2 homolog (TgPOFUT2) encoded by the TGGT1_273550 gene. Even though POFUT2 homologs are important for stabilizing motility-associated adhesins and for host infection in other apicomplexan parasites, loss of TgPOFUT2 in T. gondii had only a modest impact on MIC2 levels and the wider parasite proteome. Consistent with this, both plaque formation and tachyzoite invasion were broadly similar in the presence or absence of TgPOFUT2. These findings indicate that TgPOFUT2 O-glycosylates MIC2 and that this glycan, in contrast to previous findings in another study, is dispensable in T. gondii tachyzoites and for T. gondii infectivity.
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Affiliation(s)
- Sachin Khurana
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael J Coffey
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alan John
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alessandro D Uboldi
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Rebecca J Stewart
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Christopher J Tonkin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Ethan D Goddard-Borger
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia.
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27
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McGovern OL, Rivera-Cuevas Y, Kannan G, Narwold AJ, Carruthers VB. Intersection of endocytic and exocytic systems in Toxoplasma gondii. Traffic 2018; 19:336-353. [PMID: 29437275 DOI: 10.1111/tra.12556] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/09/2018] [Accepted: 02/10/2018] [Indexed: 12/12/2022]
Abstract
Host cytosolic proteins are endocytosed by Toxoplasma gondii and degraded in its lysosome-like compartment, the vacuolar compartment (VAC), but the dynamics and route of endocytic trafficking remain undefined. Conserved endocytic components and plant-like features suggest T. gondii endocytic trafficking involves transit through early and late endosome-like compartments (ELCs) and potentially the trans-Golgi network (TGN) as in plants. However, exocytic trafficking to regulated secretory organelles, micronemes and rhoptries, also proceeds through ELCs and requires classical endocytic components, including a dynamin-related protein, DrpB. Here, we show that host cytosolic proteins are endocytosed within 7 minutes post-invasion, trafficked through ELCs en route to the VAC, and degraded within 30 minutes. We could not definitively interpret if ingested protein is trafficked through the TGN. We also found that parasites ingest material from the host cytosol throughout the parasite cell cycle. Ingested host proteins colocalize with immature microneme proteins, proM2AP and proMIC5, in transit to the micronemes, but not with the immature rhoptry protein proRON4, indicating that endocytic trafficking of ingested protein intersects with exocytic trafficking of microneme proteins. Finally, we show that conditional expression of a DrpB dominant negative mutant increases T. gondii ingestion of host-derived proteins, suggesting that DrpB is not required for parasite endocytosis.
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Affiliation(s)
- Olivia L McGovern
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Yolanda Rivera-Cuevas
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Andrew J Narwold
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan
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28
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Zwicker JD, Diaz NA, Guerra AJ, Kirchhoff PD, Wen B, Sun D, Carruthers VB, Larsen SD. Optimization of dipeptidic inhibitors of cathepsin L for improved Toxoplasma gondii selectivity and CNS permeability. Bioorg Med Chem Lett 2018; 28:1972-1980. [PMID: 29650289 DOI: 10.1016/j.bmcl.2018.03.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/07/2018] [Indexed: 10/17/2022]
Abstract
The neurotropic protozoan Toxoplasma gondii is the second leading cause of death due to foodborne illness in the US, and has been designated as one of five neglected parasitic infections by the Center for Disease Control and Prevention. Currently, no treatment options exist for the chronic dormant-phase Toxoplasma infection in the central nervous system (CNS). T. gondii cathepsin L (TgCPL) has recently been implicated as a novel viable target for the treatment of chronic toxoplasmosis. In this study, we report the first body of SAR work aimed at developing potent inhibitors of TgCPL with selectivity vs the human cathepsin L. Starting from a known inhibitor of human cathepsin L, and guided by structure-based design, we were able to modulate the selectivity for Toxoplasma vs human CPL by nearly 50-fold while modifying physiochemical properties to be more favorable for metabolic stability and CNS penetrance. The overall potency of our inhibitors towards TgCPL was improved from 2 μM to as low as 110 nM and we successfully demonstrated that an optimized analog 18b is capable of crossing the BBB (0.5 brain/plasma). This work is an important first step toward development of a CNS-penetrant probe to validate TgCPL as a feasible target for the treatment of chronic toxoplasmosis.
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Affiliation(s)
- Jeffery D Zwicker
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, United States; Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - Nicolas A Diaz
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, United States; Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - Alfredo J Guerra
- Department of Immunology and Microbiology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Paul D Kirchhoff
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - Bo Wen
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI 48109, United States
| | - Duxin Sun
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI 48109, United States
| | - Vern B Carruthers
- Department of Immunology and Microbiology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Scott D Larsen
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, United States; Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109, United States.
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29
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Steinberg HE, Russo P, Angulo N, Ynocente R, Montoya C, Diestra A, Ferradas C, Schiaffino F, Florentini E, Jimenez J, Calderón M, Carruthers VB, Gilman RH, Liotta L, Luchini A. Toward detection of toxoplasmosis from urine in mice using hydro-gel nanoparticles concentration and parallel reaction monitoring mass spectrometry. Nanomedicine 2017; 14:461-469. [PMID: 29203146 DOI: 10.1016/j.nano.2017.11.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 11/15/2017] [Accepted: 11/19/2017] [Indexed: 11/30/2022]
Abstract
Diagnosis of clinical toxoplasmosis remains a challenge, thus limiting the availability of human clinical samples. Though murine models are an approximation of human response, their definitive infection status and tissue availability make them critical to the diagnostic development process. Hydrogel mesh nanoparticles were used to concentrate antigen to detectable levels for mass spectrometry. Seven Toxoplasma gondii isolates were used to develop a panel of potential peptide sequences for detection by parallel reaction monitoring (PRM) mass spectrometry. Nanoparticles were incubated with decreasing concentrations of tachyzoite lysate to explore the limits of detection of PRM. Mice whose toxoplasmosis infection status was confirmed by quantitative real-time PCR had urine tested by PRM after hydrogel mesh concentration for known T. gondii peptides. Peptides from GRA1, GRA12, ROP4, ROP5, SAG1, and SAG2A proteins were detected by PRM after nanoparticle concentration of urine, confirming detection of T. gondii antigen in the urine of an infected mouse.
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Affiliation(s)
- Hannah E Steinberg
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
| | - Paul Russo
- Center for Applied Proteomics and Molecular Medicine, George Mason University, VA, USA
| | - Noelia Angulo
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Raúl Ynocente
- Laboratorio de Parasitología de Fauna Silvestre y Zoonosis, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - Cristina Montoya
- Laboratorio de Parasitología de Fauna Silvestre y Zoonosis, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - Andrea Diestra
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Cusi Ferradas
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Francesca Schiaffino
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Edgar Florentini
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Juan Jimenez
- Laboratorio de Parasitología de Fauna Silvestre y Zoonosis, Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - Maritza Calderón
- Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Robert H Gilman
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Lance Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, VA, USA
| | - Alessandra Luchini
- Center for Applied Proteomics and Molecular Medicine, George Mason University, VA, USA
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30
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Guerra AJ, Carruthers VB. Structural Features of Apicomplexan Pore-Forming Proteins and Their Roles in Parasite Cell Traversal and Egress. Toxins (Basel) 2017; 9:toxins9090265. [PMID: 28850082 PMCID: PMC5618198 DOI: 10.3390/toxins9090265] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/20/2017] [Accepted: 08/22/2017] [Indexed: 01/18/2023] Open
Abstract
Apicomplexan parasites cause diseases, including malaria and toxoplasmosis, in a range of hosts, including humans. These intracellular parasites utilize pore-forming proteins that disrupt host cell membranes to either traverse host cells while migrating through tissues or egress from the parasite-containing vacuole after replication. This review highlights recent insight gained from the newly available three-dimensional structures of several known or putative apicomplexan pore-forming proteins that contribute to cell traversal or egress. These new structural advances suggest that parasite pore-forming proteins use distinct mechanisms to disrupt host cell membranes at multiple steps in parasite life cycles. How proteolytic processing, secretion, environment, and the accessibility of lipid receptors regulate the membranolytic activities of such proteins is also discussed.
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Affiliation(s)
- Alfredo J Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109-5620, USA.
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109-5620, USA.
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31
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Xiao J, Li Y, Gressitt KL, He H, Kannan G, Schultz TL, Svezhova N, Carruthers VB, Pletnikov MV, Yolken RH, Severance EG. Cerebral complement C1q activation in chronic Toxoplasma infection. Brain Behav Immun 2016; 58:52-56. [PMID: 27109609 PMCID: PMC5067173 DOI: 10.1016/j.bbi.2016.04.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 04/07/2016] [Accepted: 04/20/2016] [Indexed: 11/19/2022] Open
Abstract
Exposure to the neurotropic parasite, Toxoplasma gondii, causes significant brain and behavioral anomalies in humans and other mammals. Understanding the cellular mechanisms of T. gondii-generated brain pathologies would aid the advancement of novel strategies to reduce disease. Complement factor C1q is part of a classic immune pathway that functions peripherally to tag and remove infectious agents and cellular debris from circulation. In the developing and adult brain, C1q modifies neuronal architecture through synapse marking and pruning. T. gondii exposure and complement activation have both been implicated in the development of complex brain disorders such as schizophrenia. Thus, it seems logical that mechanistically, the physiological pathways associated with these two factors are connected. We employed a rodent model of chronic infection to investigate the extent to which cyst presence in the brain triggers activation of cerebral C1q. Compared to uninfected mice, cortical C1q was highly expressed at both the RNA and protein levels in infected animals bearing a high cyst burden. In these mice, C1q protein localized to cytoplasm, adjacent to GFAP-labeled astrocytes, near degenerating cysts, and in punctate patterns along processes. In summary, our results demonstrated an upregulation of cerebral C1q in response to latent T. gondii infection. Our data preliminarily suggest that this complement activity may aid in the clearance of this parasite from the CNS and in so doing, have consequences for the connectivity of neighboring cells and synapses.
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Affiliation(s)
- Jianchun Xiao
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA
| | - Ye Li
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA
| | - Kristin L Gressitt
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA
| | - Helen He
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA
| | - Geetha Kannan
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nadezhda Svezhova
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Mikhail V Pletnikov
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert H Yolken
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA
| | - Emily G Severance
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Blalock 1105, Baltimore, MD 21287-4933, USA.
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32
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Sidik SM, Huet D, Ganesan SM, Huynh MH, Wang T, Nasamu AS, Thiru P, Saeij JPJ, Carruthers VB, Niles JC, Lourido S. A Genome-wide CRISPR Screen in Toxoplasma Identifies Essential Apicomplexan Genes. Cell 2016; 166:1423-1435.e12. [PMID: 27594426 PMCID: PMC5017925 DOI: 10.1016/j.cell.2016.08.019] [Citation(s) in RCA: 480] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/25/2016] [Accepted: 08/05/2016] [Indexed: 12/11/2022]
Abstract
Apicomplexan parasites are leading causes of human and livestock diseases such as malaria and toxoplasmosis, yet most of their genes remain uncharacterized. Here, we present the first genome-wide genetic screen of an apicomplexan. We adapted CRISPR/Cas9 to assess the contribution of each gene from the parasite Toxoplasma gondii during infection of human fibroblasts. Our analysis defines ∼200 previously uncharacterized, fitness-conferring genes unique to the phylum, from which 16 were investigated, revealing essential functions during infection of human cells. Secondary screens identify as an invasion factor the claudin-like apicomplexan microneme protein (CLAMP), which resembles mammalian tight-junction proteins and localizes to secretory organelles, making it critical to the initiation of infection. CLAMP is present throughout sequenced apicomplexan genomes and is essential during the asexual stages of the malaria parasite Plasmodium falciparum. These results provide broad-based functional information on T. gondii genes and will facilitate future approaches to expand the horizon of antiparasitic interventions.
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Affiliation(s)
- Saima M Sidik
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Diego Huet
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Suresh M Ganesan
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Tim Wang
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Armiyaw S Nasamu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Prathapan Thiru
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Jeroen P J Saeij
- Department of Pathology, Microbiology and Immunology, University of California, Davis, Davis, CA 95616, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
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33
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Vidadala RSR, Rivas KL, Ojo KK, Hulverson MA, Zambriski JA, Bruzual I, Schultz TL, Huang W, Zhang Z, Scheele S, DeRocher AE, Choi R, Barrett LK, Siddaramaiah LK, Hol WGJ, Fan E, Merritt EA, Parsons M, Freiberg G, Marsh K, Kempf DJ, Carruthers VB, Isoherranen N, Doggett JS, Van Voorhis WC, Maly DJ. Development of an Orally Available and Central Nervous System (CNS) Penetrant Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitor with Minimal Human Ether-a-go-go-Related Gene (hERG) Activity for the Treatment of Toxoplasmosis. J Med Chem 2016; 59:6531-46. [PMID: 27309760 DOI: 10.1021/acs.jmedchem.6b00760] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New therapies are needed for the treatment of toxoplasmosis, which is a disease caused by the protozoan parasite Toxoplasma gondii. To this end, we previously developed a potent and selective inhibitor (compound 1) of Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) that possesses antitoxoplasmosis activity in vitro and in vivo. Unfortunately, 1 has potent human ether-a-go-go-related gene (hERG) inhibitory activity, associated with long Q-T syndrome, and consequently presents a cardiotoxicity risk. Here, we describe the identification of an optimized TgCDPK1 inhibitor 32, which does not have a hERG liability and possesses a favorable pharmacokinetic profile in small and large animals. 32 is CNS-penetrant and highly effective in acute and latent mouse models of T. gondii infection, significantly reducing the amount of parasite in the brain, spleen, and peritoneal fluid and reducing brain cysts by >85%. These properties make 32 a promising lead for the development of a new antitoxoplasmosis therapy.
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Affiliation(s)
- Rama Subba Rao Vidadala
- Department of Chemistry, University of Washington , Seattle, Washington 98195, United States
| | - Kasey L Rivas
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States
| | - Kayode K Ojo
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States
| | - Matthew A Hulverson
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States
| | - Jennifer A Zambriski
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University , Pullman, Washington 99164, United States
| | - Igor Bruzual
- Portland VA Medical Center , Portland, Oregon 97239, United States
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States
| | - Wenlin Huang
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Suzanne Scheele
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109, United States
| | - Amy E DeRocher
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109, United States
| | - Ryan Choi
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States
| | - Lynn K Barrett
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States
| | | | - Wim G J Hol
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Erkang Fan
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Ethan A Merritt
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States
| | - Marilyn Parsons
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, Washington 98109, United States.,Department of Global Health, University of Washington , Seattle, Washington 98195, United States
| | - Gail Freiberg
- AbbVie , North Chicago, Illinois 60064, United States
| | - Kennan Marsh
- AbbVie , North Chicago, Illinois 60064, United States
| | - Dale J Kempf
- AbbVie , North Chicago, Illinois 60064, United States
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States
| | - Nina Isoherranen
- Department of Pharmaceutics, University of Washington , Seattle, Washington 98195, United States
| | - J Stone Doggett
- Portland VA Medical Center , Portland, Oregon 97239, United States
| | - Wesley C Van Voorhis
- Department of Medicine, Division of Allergy and Infectious Diseases, and the Center for Emerging and Re-Emerging Infectious Diseases (CERID), University of Washington , Seattle, Washington 98109, United States.,Department of Global Health, University of Washington , Seattle, Washington 98195, United States
| | - Dustin J Maly
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States.,Department of Chemistry, University of Washington , Seattle, Washington 98195, United States
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34
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Abstract
How the protozoan pathogen Toxoplasma gondii and related parasites shuttle proteins through their intricate system of endomembranous compartments remains unclear. Sangaré et al. show that the Toxoplasma retromer complex is essential for parasite viability through its role in protein targeting to multiple locales and its interactions with newly identified partners.
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Affiliation(s)
- Olivia L McGovern
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5620, USA
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5620, USA.
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35
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Tomasik J, Schultz TL, Kluge W, Yolken RH, Bahn S, Carruthers VB. Shared Immune and Repair Markers During Experimental Toxoplasma Chronic Brain Infection and Schizophrenia. Schizophr Bull 2016; 42:386-95. [PMID: 26392628 PMCID: PMC4753603 DOI: 10.1093/schbul/sbv134] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chronic neurologic infection with Toxoplasma gondii is relatively common in humans and is one of the strongest known risk factors for schizophrenia. Nevertheless, the exact neuropathological mechanisms linking T gondii infection and schizophrenia remain unclear. Here we utilize a mouse model of chronic T gondii infection to identify protein biomarkers that are altered in serum and brain samples at 2 time points during chronic infection. Furthermore, we compare the identified biomarkers to those differing between "postmortem" brain samples from 35 schizophrenia patients and 33 healthy controls. Our findings suggest that T gondii infection causes substantial and widespread immune activation indicative of neural damage and reactive tissue repair in the animal model that partly overlaps with changes observed in the brains of schizophrenia patients. The overlapping changes include increases in C-reactive protein (CRP), interleukin-1 beta (IL-1β), interferon gamma (IFNγ), plasminogen activator inhibitor 1 (PAI-1), tissue inhibitor of metalloproteinases 1 (TIMP-1), and vascular cell adhesion molecule 1 (VCAM-1). Potential roles of these factors in the pathogenesis of schizophrenia and toxoplasmosis are discussed. Identifying a defined set of markers shared within the pathophysiological landscape of these diseases could be a key step towards understanding their specific contributions to pathogenesis.
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Affiliation(s)
- Jakub Tomasik
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK;,Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Tracey L. Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI
| | - Wolfgang Kluge
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Robert H. Yolken
- Stanley Laboratory of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, MD
| | - Sabine Bahn
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK;,Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands;, Joint last authors/ these authors contributed equally to the study
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI;, Joint last authors/ these authors contributed equally to the study
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36
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Pszenny V, Ehrenman K, Romano JD, Kennard A, Schultz A, Roos DS, Grigg ME, Carruthers VB, Coppens I. A Lipolytic Lecithin:Cholesterol Acyltransferase Secreted by Toxoplasma Facilitates Parasite Replication and Egress. J Biol Chem 2015; 291:3725-46. [PMID: 26694607 DOI: 10.1074/jbc.m115.671974] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Indexed: 11/06/2022] Open
Abstract
The protozoan parasite Toxoplasma gondii develops within a parasitophorous vacuole (PV) in mammalian cells, where it scavenges cholesterol. When cholesterol is present in excess in its environment, the parasite expulses this lipid into the PV or esterifies it for storage in lipid bodies. Here, we characterized a unique T. gondii homologue of mammalian lecithin:cholesterol acyltransferase (LCAT), a key enzyme that produces cholesteryl esters via transfer of acyl groups from phospholipids to the 3-OH of free cholesterol, leading to the removal of excess cholesterol from tissues. TgLCAT contains a motif characteristic of serine lipases "AHSLG" and the catalytic triad consisting of serine, aspartate, and histidine (SDH) from LCAT enzymes. TgLCAT is secreted by the parasite, but unlike other LCAT enzymes it is cleaved into two proteolytic fragments that share the residues of the catalytic triad and need to be reassembled to reconstitute enzymatic activity. TgLCAT uses phosphatidylcholine as substrate to form lysophosphatidylcholine that has the potential to disrupt membranes. The released fatty acid is transferred to cholesterol, but with a lower transesterification activity than mammalian LCAT. TgLCAT is stored in a subpopulation of dense granule secretory organelles, and following secretion, it localizes to the PV and parasite plasma membrane. LCAT-null parasites have impaired growth in vitro, reduced virulence in animals, and exhibit delays in egress from host cells. Parasites overexpressing LCAT show increased virulence and faster egress. These observations demonstrate that TgLCAT influences the outcome of an infection, presumably by facilitating replication and egress depending on the developmental stage of the parasite.
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Affiliation(s)
- Viviana Pszenny
- From the Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, the Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Karen Ehrenman
- From the Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Julia D Romano
- From the Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205
| | - Andrea Kennard
- the Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Aric Schultz
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - David S Roos
- the Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Michael E Grigg
- the Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Vern B Carruthers
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - Isabelle Coppens
- From the Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205,
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37
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Affiliation(s)
- Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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38
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Affiliation(s)
- Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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39
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Lunghi M, Galizi R, Magini A, Carruthers VB, Di Cristina M. Expression of the glycolytic enzymes enolase and lactate dehydrogenase during the early phase ofToxoplasmadifferentiation is regulated by an intron retention mechanism. Mol Microbiol 2015; 96:1159-75. [DOI: 10.1111/mmi.12999] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Matteo Lunghi
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
| | - Roberto Galizi
- Department of Experimental Medicine; University of Perugia; Perugia Italy
| | - Alessandro Magini
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
| | - Vern B. Carruthers
- Department of Microbiology and Immunology; University of Michigan Medical School; Ann Arbor MI USA
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology; University of Perugia; Perugia Italy
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40
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Huynh MH, Liu B, Henry M, Liew L, Matthews SJ, Carruthers VB. Structural basis of Toxoplasma gondii MIC2-associated protein interaction with MIC2. J Biol Chem 2014; 290:1432-41. [PMID: 25411252 DOI: 10.1074/jbc.m114.613646] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Toxoplasma gondii parasites must actively invade host cells to propagate. Secretory microneme proteins have been shown to be important for both gliding motility and active invasion. MIC2-M2AP is a protein complex that is essential for productive motility and rapid invasion by binding to host cell surface receptors. To investigate the architecture of the MIC2 and M2AP complex, we identified the minimal domains sufficient for interaction and solved the NMR solution structure of the globular domain of M2AP. We found that M2AP adopts a modified galectin fold similar to the C-terminal domain of another microneme protein, MIC1. NMR and immunoprecipitation analyses implicated hydrophobic residues on one face of the M2AP galectin fold in binding to the membrane proximal sixth thrombospondin type I repeat domain of MIC2. Our findings provide a second example of a galectin fold adapted for microneme protein-protein interactions and suggest a conserved strategy for the assembly and folding of diverse protein complexes.
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Affiliation(s)
- My-Hang Huynh
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
| | - Bing Liu
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Maud Henry
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Lloyd Liew
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Stephen J Matthews
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Vern B Carruthers
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
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Roiko MS, Svezhova N, Carruthers VB. Acidification Activates Toxoplasma gondii Motility and Egress by Enhancing Protein Secretion and Cytolytic Activity. PLoS Pathog 2014; 10:e1004488. [PMID: 25375818 PMCID: PMC4223073 DOI: 10.1371/journal.ppat.1004488] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [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: 04/21/2014] [Accepted: 09/24/2014] [Indexed: 12/03/2022] Open
Abstract
Pathogenic microbes rely on environmental cues to initiate key events during infection such as differentiation, motility, egress and invasion of cells or tissues. Earlier investigations showed that an acidic environment activates motility of the protozoan parasite T. gondii. Conversely, potassium ions, which are abundant in the intracellular milieu that bathes immotile replicating parasites, suppress motility. Since motility is required for efficient parasite cell invasion and egress we sought to better understand its regulation by environmental cues. We found that low pH stimulates motility by triggering Ca2+-dependent secretion of apical micronemes, and that this cue is sufficient to overcome suppression by potassium ions and drive parasite motility, cell invasion and egress. We also discovered that acidification promotes membrane binding and cytolytic activity of perforin-like protein 1 (PLP1), a pore-forming protein required for efficient egress. Agents that neutralize pH reduce the efficiency of PLP1-dependent perforation of host membranes and compromise egress. Finally, although low pH stimulation of microneme secretion promotes cell invasion, it also causes PLP1-dependent damage to host cells, suggesting a mechanism by which neutral extracellular pH subdues PLP1 activity to allow cell invasion without overt damage to the target cell. These findings implicate acidification as a signal to activate microneme secretion and confine cytolytic activity to egress without compromising the viability of the next cell infected. Toxoplasma and related parasites including those that cause malaria are obligate intracellular pathogens that replicate within a specialized compartment termed the parasitophorous vacuole. To infect new host cells these parasites must first escape from the parasitophorous vacuole and other limiting membranes of the currently infected cell. Escape, or egress as it is often called, depends on the timely release of adhesive proteins and lysis factors from secretory organelles called micronemes. Although this secretory event is crucial for egress, the natural environmental cues that trigger microneme secretion remain poorly defined. Here we discover that acidification of the parasitophorous vacuole is sufficient to trigger microneme secretion and promote the activity of a lysis factor called PLP1. We also show that pH-neutralizing drugs inhibit egress and provide evidence of parasitophorous vacuole acidification approximately coinciding with parasite egress from infected host cells. The findings support a working model in which acidification activates microneme dependent motility and lytic activity to execute egress and destruction of infected cells. The results also provide insight into how PLP1 lytic activity is stimulated during egress in an acidic environment and subsequently suppressed by the neutral extracellular environment, thus permitting cell invasion with minimal damage to the next target cell.
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Affiliation(s)
- Marijo S. Roiko
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Nadezhda Svezhova
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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Schultz TL, Hencken CP, Woodard LE, Posner GH, Yolken RH, Jones-Brando L, Carruthers VB. A Thiazole Derivative of Artemisinin Moderately ReducesToxoplasma gondiiCyst Burden in Infected Mice. J Parasitol 2014; 100:516-21. [DOI: 10.1645/13-451.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Liu J, Pace D, Dou Z, King TP, Guidot D, Li ZH, Carruthers VB, Moreno SNJ. A vacuolar-H(+) -pyrophosphatase (TgVP1) is required for microneme secretion, host cell invasion, and extracellular survival of Toxoplasma gondii. Mol Microbiol 2014; 93:698-712. [PMID: 24975633 DOI: 10.1111/mmi.12685] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
The vacuolar proton pyrophosphatase (H(+) -PPase) of Toxoplasma gondii (TgVP1), a membrane proton pump, localizes to acidocalcisomes and a novel lysosome-like compartment termed plant-like vacuole (PLV) or vacuolar compartment (VAC). We report the characterization of a T. gondii null mutant for the TgVP1 gene. Propagation of these mutants decreased significantly because of deficient attachment and invasion of host cells, which correlated with deficient microneme secretion. Processing of cathepsin L (CPL) in these mutants was deficient only when the parasites were incubated in the presence of low concentrations of the vacuolar H(+) -ATPase (V-H(+) -ATPase) inhibitor bafilomycin A1 , suggesting that either TgVP1 or the T. gondii V-H(+) -ATPase (TgVATPase) are sufficient to support CPL processing. The lack of TgVP1 did not affect processing of micronemal proteins, indicating that it does not contribute to proMIC maturations. The TgVP1 null mutants were more sensitive to extracellular conditions and were less virulent in mice. We demonstrate that T. gondii tachyzoites possess regulatory volume decrease capability during hypo-osmotic stress and this ability is impaired in TgVP1 null mutants implicating TgVP1 in osmoregulation. We hypothesize that osmoregulation is needed for host cell invasion and that TgVP1 plays a role during the normal lytic cycle of T. gondii.
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Affiliation(s)
- Jing Liu
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, GA, 30602-7400, USA; College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
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Muniz-Feliciano L, Van Grol J, Portillo JAC, Liew L, Liu B, Carlin CR, Carruthers VB, Matthews S, Subauste CS. Toxoplasma gondii-induced activation of EGFR prevents autophagy protein-mediated killing of the parasite. PLoS Pathog 2013; 9:e1003809. [PMID: 24367261 PMCID: PMC3868508 DOI: 10.1371/journal.ppat.1003809] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 10/19/2013] [Indexed: 12/24/2022] Open
Abstract
Toxoplasma gondii resides in an intracellular compartment (parasitophorous vacuole) that excludes transmembrane molecules required for endosome-lysosome recruitment. Thus, the parasite survives by avoiding lysosomal degradation. However, autophagy can re-route the parasitophorous vacuole to the lysosomes and cause parasite killing. This raises the possibility that T. gondii may deploy a strategy to prevent autophagic targeting to maintain the non-fusogenic nature of the vacuole. We report that T. gondii activated EGFR in endothelial cells, retinal pigment epithelial cells and microglia. Blockade of EGFR or its downstream molecule, Akt, caused targeting of the parasite by LC3(+) structures, vacuole-lysosomal fusion, lysosomal degradation and killing of the parasite that were dependent on the autophagy proteins Atg7 and Beclin 1. Disassembly of GPCR or inhibition of metalloproteinases did not prevent EGFR-Akt activation. T. gondii micronemal proteins (MICs) containing EGF domains (EGF-MICs; MIC3 and MIC6) appeared to promote EGFR activation. Parasites defective in EGF-MICs (MIC1 ko, deficient in MIC1 and secretion of MIC6; MIC3 ko, deficient in MIC3; and MIC1-3 ko, deficient in MIC1, MIC3 and secretion of MIC6) caused impaired EGFR-Akt activation and recombinant EGF-MICs (MIC3 and MIC6) caused EGFR-Akt activation. In cells treated with autophagy stimulators (CD154, rapamycin) EGFR signaling inhibited LC3 accumulation around the parasite. Moreover, increased LC3 accumulation and parasite killing were noted in CD154-activated cells infected with MIC1-3 ko parasites. Finally, recombinant MIC3 and MIC6 inhibited parasite killing triggered by CD154 particularly against MIC1-3 ko parasites. Thus, our findings identified EGFR activation as a strategy used by T. gondii to maintain the non-fusogenic nature of the parasitophorous vacuole and suggest that EGF-MICs have a novel role in affecting signaling in host cells to promote parasite survival.
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Affiliation(s)
- Luis Muniz-Feliciano
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Jennifer Van Grol
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Jose-Andres C. Portillo
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Lloyd Liew
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Bing Liu
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Cathleen R. Carlin
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Stephen Matthews
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Carlos S. Subauste
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America
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Abstract
Toxoplasma (toxoplasmosis) and Plasmodium (malaria) use unique secretory organelles for migration, cell invasion, manipulation of host cell functions, and cell egress. In particular, the apical secretory micronemes and rhoptries of apicomplexan parasites are essential for successful host infection. New findings reveal that the contents of these organelles, which are transported through the endoplasmic reticulum (ER) and Golgi, also require the parasite endosome-like system to access their respective organelles. In this review, we discuss recent findings that demonstrate that these parasites reduced their endosomal system and modified classical regulators of this pathway for the biogenesis of apical organelles.
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Affiliation(s)
- Stanislas Tomavo
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- * E-mail:
| | - Christian Slomianny
- Laboratory of Cell Physiology, INSERM U 1003, Université Lille Nord de France, Villeneuve d'Ascq, Lille, France
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
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Blackman MJ, Carruthers VB. Recent insights into apicomplexan parasite egress provide new views to a kill. Curr Opin Microbiol 2013; 16:459-64. [PMID: 23725669 PMCID: PMC3755044 DOI: 10.1016/j.mib.2013.04.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 01/20/2023]
Abstract
A hallmark of apicomplexan pathogens such as Plasmodium, Toxoplasma and Cryptosporidium is that they invade, replicate within, and then egress from their host cells. Egress usually results in lysis of the host cell, with deleterious consequences for the host. In the case of malaria, for example, much of the disease pathology is associated with cyclical waves of host erythrocyte destruction. This review highlights recent advances in mapping the signaling pathways that lead to egress and the parasite molecules involved in responding to and transmitting those signals. The review also discusses new findings for effector molecules that mediate disruption of the bounding membranes that enclose the intracellular parasite and the manner in which membrane rupture occurs to finally release invasive forms of the parasite.
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Affiliation(s)
- Michael J. Blackman
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
| | - Vern B. Carruthers
- Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5620
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Gaji RY, Huynh MH, Carruthers VB. A novel high throughput invasion screen identifies host actin regulators required for efficient cell entry by Toxoplasma gondii. PLoS One 2013; 8:e64693. [PMID: 23741372 PMCID: PMC3669402 DOI: 10.1371/journal.pone.0064693] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 04/17/2013] [Indexed: 01/08/2023] Open
Abstract
Toxoplasma gondii critically relies on cell invasion as a survival strategy to evade immune clearance during infection. Although it was widely thought that Toxoplasma entry is parasite directed and that the host cell is largely a passive victim, recent studies have suggested that host components such as microfilaments and microtubules indeed contribute to entry. Hence to identify additional host factors, we performed a high-throughput siRNA screen of a human siRNA library targeting druggable proteins using a novel inducible luciferase based invasion assay. The top 100 hits from the primary screen that showed the strongest decreases in invasion were subjected to confirmation by secondary screening, revealing 24 proteins that are potentially involved in Toxoplasma entry into host cells. Interestingly, 6 of the hits appear to affect parasite invasion by modifying host cell actin dynamics, resulting in increased deposition of F-actin at the periphery of the cell. These findings support the emerging notion that host actin dynamics are important for Toxoplasma invasion along with identifying several novel host factors that potentially participate in parasite entry.
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Affiliation(s)
- Rajshekhar Y. Gaji
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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48
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Roiko MS, Carruthers VB. Functional dissection of Toxoplasma gondii perforin-like protein 1 reveals a dual domain mode of membrane binding for cytolysis and parasite egress. J Biol Chem 2013; 288:8712-8725. [PMID: 23376275 DOI: 10.1074/jbc.m113.450932] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The recently discovered role of a perforin-like protein (PLP1) for rapid host cell egress by the protozoan parasite Toxoplasma gondii expanded the functional diversity of pore-forming proteins. Whereas PLP1 was found to be necessary for rapid egress and pathogenesis, the sufficiency for and mechanism of membrane attack were yet unknown. Here we further dissected the PLP1 knock-out phenotype, the mechanism of PLP1 pore formation, and the role of each domain by genetic complementation. We found that PLP1 is sufficient for membrane disruption and has a conserved mechanism of pore formation through target membrane binding and oligomerization to form large, multimeric membrane-embedded complexes. The highly conserved, central MACPF domain and the β-sheet-rich C-terminal domain were required for activity. Loss of the unique N-terminal extension reduced lytic activity and led to a delay in rapid egress, but did not significantly decrease virulence, suggesting that small amounts of lytic activity are sufficient for pathogenesis. We found that both N- and C-terminal domains have membrane binding activity, with the C-terminal domain being critical for function. This dual mode of membrane association may promote PLP1 activity and parasite egress in the diverse cell types in which this parasite replicates.
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Affiliation(s)
- Marijo S Roiko
- Cell and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan 48109-5630; Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109-5630
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109-5630.
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49
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Abstract
Proteases regulate key events during infection by the pervasive intracellular parasite Toxoplasma gondii. Understanding how parasite proteases mature from an inactive zymogen to an active enzyme is expected to inform new strategies for blocking their actions. Herein, we show that T. gondii cathepsin B protease (TgCPB) does not undergo self-maturation but instead requires the expression of a second papain-family cathepsin protease, TgCPL. Using recombinant enzymes we also show that TgCPL is capable of partially maturing TgCPB in vitro. Consistent with this interrelationship, antibodies with validated specificity detected TgCPB in the lysosome-like vacuolar compartment along with TgCPL. Our findings also establish that TgCPB does not localize to the rhoptries as previously reported. Accordingly, rhoptry morphology and rhoptry protein maturation are normal in TgCPB knock-out parasites. Finally, we show that although maturation of TgCPL is independent of TgCPB, it may involve an additional protease(s) in conjunction with self-maturation.
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Affiliation(s)
- Zhicheng Dou
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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50
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Saouros S, Dou Z, Henry M, Marchant J, Carruthers VB, Matthews S. Microneme protein 5 regulates the activity of Toxoplasma subtilisin 1 by mimicking a subtilisin prodomain. J Biol Chem 2012; 287:36029-40. [PMID: 22896704 DOI: 10.1074/jbc.m112.389825] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Toxoplasma gondii is the model parasite of the phylum Apicomplexa, which contains obligate intracellular parasites of medical and veterinary importance. Apicomplexans invade host cells by a multistep process involving the secretion of adhesive microneme protein (MIC) complexes. The subtilisin protease TgSUB1 trims several MICs on the parasite surface to activate gliding motility and host invasion. Although a previous study showed that expression of the secretory protein TgMIC5 suppresses TgSUB1 activity, the mechanism was unknown. Here, we solve the three-dimensional structure of TgMIC5 by nuclear magnetic resonance (NMR), revealing that it mimics a subtilisin prodomain including a flexible C-terminal peptide that may insert into the subtilisin active site. We show that TgMIC5 is an almost 50-fold more potent inhibitor of TgSUB1 activity than the small molecule inhibitor N-[N-(N-acetyl-L-leucyl)-L-leucyl]-L-norleucine (ALLN). Moreover, we demonstrate that TgMIC5 is retained on the parasite plasma membrane via its physical interaction with the membrane-anchored TgSUB1.
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Affiliation(s)
- Savvas Saouros
- Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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