51
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Bergmann A, Dou Z. Fluorescence-based Heme Quantitation in Toxoplasma Gondii. Bio Protoc 2021; 11:e4063. [PMID: 34263005 DOI: 10.21769/bioprotoc.4063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 11/02/2022] Open
Abstract
Toxoplasma gondii is a highly prevalent protozoan pathogen throughout the world. As a eukaryotic intracellular pathogen, Toxoplasma ingests nutrients from host cells to support its intracellular growth. The parasites also encode full or partial metabolic pathways for the biosynthesis of certain nutrients, such as heme. Heme is an essential nutrient in virtually all living organisms, acting as a co-factor for mitochondrial respiration complexes. Free heme is toxic to cells; therefore, it gets conjugated to proteins or other metabolites to form a "labile heme pool," which is readily available for the biosynthesis of hemoproteins. Previous literature has shown that Toxoplasma gondii carries a fully functional de novo heme biosynthesis pathway and principally depends on this pathway for intracellular survival. Our recent findings also showed that the parasite's intracellular replication is proportional to the total abundance of heme within the cells. Moreover, heme abundance is linked to mitochondrial oxygen consumption for ATP production in these parasites; thus, they may need to regulate their cellular heme levels for optimal infection when present in different environments. Therefore, quantitative measurement of heme abundance within Toxoplasma will help us to understand the roles of heme in subcellular activities such as mitochondrial respiration and other events related to energy metabolism.
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Affiliation(s)
- Amy Bergmann
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, USA.,Eukaryotic Pathogen Innovation Center (EPIC), Clemson University, Clemson, South Carolina, 29634, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, USA.,Eukaryotic Pathogen Innovation Center (EPIC), Clemson University, Clemson, South Carolina, 29634, USA
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52
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Lentini G, Ben Chaabene R, Vadas O, Ramakrishnan C, Mukherjee B, Mehta V, Lunghi M, Grossmann J, Maco B, Visentin R, Hehl AB, Korkhov VM, Soldati-Favre D. Structural insights into an atypical secretory pathway kinase crucial for Toxoplasma gondii invasion. Nat Commun 2021; 12:3788. [PMID: 34145271 PMCID: PMC8213820 DOI: 10.1038/s41467-021-24083-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/31/2021] [Indexed: 02/05/2023] Open
Abstract
Active host cell invasion by the obligate intracellular apicomplexan parasites relies on the formation of a moving junction, which connects parasite and host cell plasma membranes during entry. Invading Toxoplasma gondii tachyzoites secrete their rhoptry content and insert a complex of RON proteins on the cytoplasmic side of the host cell membrane providing an anchor to which the parasite tethers. Here we show that a rhoptry-resident kinase RON13 is a key virulence factor that plays a crucial role in host cell entry. Cryo-EM, kinase assays, phosphoproteomics and cellular analyses reveal that RON13 is a secretory pathway kinase of atypical structure that phosphorylates rhoptry proteins including the components of the RON complex. Ultimately, RON13 kinase activity controls host cell invasion by anchoring the moving junction at the parasite-host cell interface.
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Affiliation(s)
- Gaëlle Lentini
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Rouaa Ben Chaabene
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Oscar Vadas
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Chandra Ramakrishnan
- grid.7400.30000 0004 1937 0650Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Budhaditya Mukherjee
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland ,grid.429017.90000 0001 0153 2859Present Address: School of Medical Science and Technology, IIT Kharagpur, India
| | - Ved Mehta
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Matteo Lunghi
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Jonas Grossmann
- grid.7400.30000 0004 1937 0650Functional Genomic Center Zurich, ETH Zurich and University of Zurich, Zurich, Switzerland ,grid.419765.80000 0001 2223 3006The Swiss Institute of Bioinformatics, SIB, Lausanne, Switzerland
| | - Bohumil Maco
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Rémy Visentin
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Adrian B. Hehl
- grid.7400.30000 0004 1937 0650Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Volodymyr M. Korkhov
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland ,grid.5991.40000 0001 1090 7501Paul Scherrer Institute, Villigen, Switzerland
| | - Dominique Soldati-Favre
- grid.8591.50000 0001 2322 4988Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
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53
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Chiappino-Pepe A, Hatzimanikatis V. PhenoMapping: a protocol to map cellular phenotypes to metabolic bottlenecks, identify conditional essentiality, and curate metabolic models. STAR Protoc 2021; 2:100280. [PMID: 33532729 PMCID: PMC7829271 DOI: 10.1016/j.xpro.2020.100280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Targeted identification of cellular processes responsible for a phenotype is of major importance in guiding efforts in bioengineering and medicine. Genome-scale metabolic models (GEMs) are widely used to integrate various types of omics data and study the cellular physiology under different conditions. Here, we present PhenoMapping, a protocol that uses GEMs, omics, and phenotypic data to map cellular processes and observed phenotypes. PhenoMapping also classifies genes as conditionally and unconditionally essential and guides a comprehensive curation of GEMs. For complete details on the use and execution of this protocol, please refer to Stanway et al. (2019) and Krishnan et al. (2020).
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Affiliation(s)
- Anush Chiappino-Pepe
- Laboratory of Computational Systems Biotechnology, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, Switzerland
| | - Vassily Hatzimanikatis
- Laboratory of Computational Systems Biotechnology, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, Switzerland
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54
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Bergersen KV, Barnes A, Worth D, David C, Wilson EH. Targeted Transcriptomic Analysis of C57BL/6 and BALB/c Mice During Progressive Chronic Toxoplasma gondii Infection Reveals Changes in Host and Parasite Gene Expression Relating to Neuropathology and Resolution. Front Cell Infect Microbiol 2021; 11:645778. [PMID: 33816350 PMCID: PMC8012756 DOI: 10.3389/fcimb.2021.645778] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 02/23/2021] [Indexed: 02/06/2023] Open
Abstract
Toxoplasma gondii is a resilient parasite that infects a multitude of warm-blooded hosts and results in a lifelong chronic infection requiring continuous responses by the host. Chronic infection is characterized by a balanced immune response and neuropathology that are driven by changes in gene expression. Previous research pertaining to these processes has been conducted in various mouse models, and much knowledge of infection-induced gene expression changes has been acquired through the use of high throughput sequencing techniques in different mouse strains and post-mortem human studies. However, lack of infection time course data poses a prominent missing link in the understanding of chronic infection, and there is still much that is unknown regarding changes in genes specifically relating to neuropathology and resulting repair mechanisms as infection progresses throughout the different stages of chronicity. In this paper, we present a targeted approach to gene expression analysis during T. gondii infection through the use of NanoString nCounter gene expression assays. Wild type C57BL/6 and BALB/c background mice were infected, and transcriptional changes in the brain were evaluated at 14, 28, and 56 days post infection. Results demonstrate a dramatic shift in both previously demonstrated and novel gene expression relating to neuropathology and resolution in C57BL/6 mice. In addition, comparison between BALB/c and C57BL/6 mice demonstrate initial differences in gene expression that evolve over the course of infection and indicate decreased neuropathology and enhanced repair in BALB/c mice. In conclusion, these studies provide a targeted approach to gene expression analysis in the brain during infection and provide elaboration on previously identified transcriptional changes and also offer insights into further understanding the complexities of chronic T. gondii infection.
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Affiliation(s)
- Kristina V Bergersen
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Ashli Barnes
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Danielle Worth
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Clement David
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States.,NanoString Technologies, Seattle, WA, United States
| | - Emma H Wilson
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
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55
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Krishnan A, Soldati-Favre D. Amino Acid Metabolism in Apicomplexan Parasites. Metabolites 2021; 11:61. [PMID: 33498308 PMCID: PMC7909243 DOI: 10.3390/metabo11020061] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/05/2021] [Accepted: 01/14/2021] [Indexed: 12/22/2022] Open
Abstract
Obligate intracellular pathogens have coevolved with their host, leading to clever strategies to access nutrients, to combat the host's immune response, and to establish a safe niche for intracellular replication. The host, on the other hand, has also developed ways to restrict the replication of invaders by limiting access to nutrients required for pathogen survival. In this review, we describe the recent advancements in both computational methods and high-throughput -omics techniques that have been used to study and interrogate metabolic functions in the context of intracellular parasitism. Specifically, we cover the current knowledge on the presence of amino acid biosynthesis and uptake within the Apicomplexa phylum, focusing on human-infecting pathogens: Toxoplasma gondii and Plasmodium falciparum. Given the complex multi-host lifecycle of these pathogens, we hypothesize that amino acids are made, rather than acquired, depending on the host niche. We summarize the stage specificities of enzymes revealed through transcriptomics data, the relevance of amino acids for parasite pathogenesis in vivo, and the role of their transporters. Targeting one or more of these pathways may lead to a deeper understanding of the specific contributions of biosynthesis versus acquisition of amino acids and to design better intervention strategies against the apicomplexan parasites.
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Affiliation(s)
- Aarti Krishnan
- Department of Microbiology and Molecular Medicine, University of Geneva, CMU, Rue Michel-Servet 1, 1211 Geneva, Switzerland;
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56
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Ward AI, Olmo F, Atherton RL, Taylor MC, Kelly JM. Trypanosoma cruzi amastigotes that persist in the colon during chronic stage murine infections have a reduced replication rate. Open Biol 2020; 10:200261. [PMID: 33321060 PMCID: PMC7776577 DOI: 10.1098/rsob.200261] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Chronic Trypanosoma cruzi infections are typically lifelong, with small numbers of parasites surviving in restricted tissue sites, which include the gastrointestinal tract. There is considerable debate about the replicative status of these persistent parasites and whether there is a role for dormancy in long-term infection. Here, we investigated T. cruzi proliferation in the colon of chronically infected mice using 5-ethynyl-2′deoxyuridine incorporation into DNA to provide ‘snapshots’ of parasite replication status. Highly sensitive imaging of the extremely rare infection foci, at single-cell resolution, revealed that parasites are three times more likely to be in S-phase during the acute stage than during the chronic stage. By implication, chronic infections of the colon are associated with a reduced rate of parasite replication. Despite this, very few host cells survived infection for more than 14 days, suggesting that T. cruzi persistence continues to involve regular cycles of replication, host cell lysis and re-infection. We could find no evidence for wide-spread dormancy in parasites that persist in this tissue reservoir.
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Affiliation(s)
- Alexander I Ward
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Francisco Olmo
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Richard L Atherton
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Martin C Taylor
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - John M Kelly
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
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57
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Martorelli Di Genova B, Knoll LJ. Comparisons of the Sexual Cycles for the Coccidian Parasites Eimeria and Toxoplasma. Front Cell Infect Microbiol 2020; 10:604897. [PMID: 33381466 PMCID: PMC7768002 DOI: 10.3389/fcimb.2020.604897] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
Toxoplasma gondii and Eimeria spp. are widely prevalent Coccidian parasites that undergo sexual reproduction during their life cycle. T. gondii can infect any warm-blooded animal in its asexual cycle; however, its sexual cycle is restricted to felines. Eimeria spp. are usually restricted to one host species, and their whole life cycle is completed within this same host. The literature reviewed in this article comprises the recent findings regarding the unique biology of the sexual development of T. gondii and Eimeria spp. The molecular basis of sex in these pathogens has been significantly unraveled by new findings in parasite differentiation along with transcriptional analysis of T. gondii and Eimeria spp. pre-sexual and sexual stages. Focusing on the metabolic networks, analysis of these transcriptome datasets shows enrichment for several different metabolic pathways. Transcripts for glycolysis enzymes are consistently more abundant in T. gondii cat infection stages than the asexual tachyzoite stage and Eimeria spp. merozoite and gamete stages compared to sporozoites. Recent breakthroughs in host-pathogen interaction and host restriction have significantly expanded the understating of the unique biology of these pathogens. This review aims to critically explore advances in the sexual cycle of Coccidia parasites with the ultimate goal of comparing and analyzing the sexual cycle of Eimeria spp. and T. gondii.
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Affiliation(s)
| | - Laura J. Knoll
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, United States
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58
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Zhang Y, Wang C, Jia H. Biogenesis and maintenance of the apicoplast in model apicomplexan parasites. Parasitol Int 2020; 81:102270. [PMID: 33321224 DOI: 10.1016/j.parint.2020.102270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 11/27/2022]
Abstract
The apicoplast is a non-photosynthetic relict plastid of Apicomplexa that evolved from a secondary symbiotic system. During its evolution, most of the genes derived from its alga ancestor were lost. Only genes involved in several valuable metabolic pathways, such as the synthesis of isoprenoid precursors, heme, and fatty acids, have been transferred to the host genome and retained to help these parasites adapt to a complex life cycle and various living environments. The biological function of an apicoplast is essential for most apicomplexan parasites. Considering their potential as drug targets, the metabolic functions of this symbiotic organelle have been intensively investigated through computational and biological means. Moreover, we know that not only organellar metabolic functions are linked with other organelles, but also their biogenesis processes have developed and evolved to tailor their biological functions and proper inheritance. Several distinct features have been found in the biogenesis process of apicoplasts. For example, the apicoplast borrows a dynamin-related protein (DrpA) from its host to implement organelle division. The autophagy system has also been repurposed for linking the apicoplast and centrosome during replication and the division process. However, many vital questions remain to be answered about how these parasites maintain and properly inherit this symbiotic organelle. Here we review our current knowledge about its biogenesis process and discuss several critical questions remaining to be answered in this field.
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Affiliation(s)
- Ying Zhang
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province 163319, PR China; State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Haping Street 678, Nangang District, Harbin 150069, PR China
| | - Chunren Wang
- Heilongjiang Provincial Key Laboratory of Prevention and Control of Bovine Diseases, College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province 163319, PR China
| | - Honglin Jia
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Haping Street 678, Nangang District, Harbin 150069, PR China.
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59
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Mévélec MN, Lakhrif Z, Dimier-Poisson I. Key Limitations and New Insights Into the Toxoplasma gondii Parasite Stage Switching for Future Vaccine Development in Human, Livestock, and Cats. Front Cell Infect Microbiol 2020; 10:607198. [PMID: 33324583 PMCID: PMC7724089 DOI: 10.3389/fcimb.2020.607198] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/19/2020] [Indexed: 12/19/2022] Open
Abstract
Toxoplasmosis is a parasitic disease affecting human, livestock and cat. Prophylactic strategies would be ideal to prevent infection. In a One Health vaccination approach, the objectives would be the prevention of congenital disease in both women and livestock, prevention/reduction of T. gondii tissue cysts in food-producing animals; and oocyst shedding in cats. Over the last few years, an explosion of strategies for vaccine development, especially due to the development of genetic-engineering technologies has emerged. The field of vaccinology has been exploring safer vaccines by the generation of recombinant immunogenic proteins, naked DNA vaccines, and viral/bacterial recombinants vectors. These strategies based on single- or few antigens, are less efficacious than recombinant live-attenuated, mostly tachyzoite T. gondii vaccine candidates. Reflections on the development of an anti-Toxoplasma vaccine must focus not only on the appropriate route of administration, capable of inducing efficient immune response, but also on the choice of the antigen (s) of interest and the associated delivery systems. To answer these questions, the choice of the animal model is essential. If mice helped in understanding the protection mechanisms, the data obtained cannot be directly transposed to humans, livestock and cats. Moreover, effectiveness vaccines should elicit strong and protective humoral and cellular immune responses at both local and systemic levels against the different stages of the parasite. Finally, challenge protocols should use the oral route, major natural route of infection, either by feeding tissue cysts or oocysts from different T. gondii strains. Effective Toxoplasma vaccines depend on our understanding of the (1) protective host immune response during T. gondii invasion and infection in the different hosts, (2) manipulation and modulation of host immune response to ensure survival of the parasites able to evade and subvert host immunity, (3) molecular mechanisms that define specific stage development. This review presents an overview of the key limitations for the development of an effective vaccine and highlights the contributions made by recent studies on the mechanisms behind stage switching to offer interesting perspectives for vaccine development.
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Affiliation(s)
| | - Zineb Lakhrif
- Team BioMAP, Université de Tours, INRAE, ISP, Tours, France
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60
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Metabolite salvage and restriction during infection - a tug of war between Toxoplasma gondii and its host. Curr Opin Biotechnol 2020; 68:104-114. [PMID: 33202353 DOI: 10.1016/j.copbio.2020.09.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/28/2020] [Indexed: 02/03/2023]
Abstract
The apicomplexans, including the coccidian pathogen Toxoplasma gondii, are obligate intracellular parasites whose growth and development are intricately linked to the metabolism of their host. T. gondii depends on its host for the salvage of energy sources, building blocks, vitamins and cofactors to survive and replicate. Additionally, host metabolites directly impact on the parasite life cycle development by triggering or halting differentiation. Although T. gondii infects a wide range of host cells, it has evolved to modulate and maximally exploit its host's metabolism. In return the host has developed strategies to restrict parasite access to metabolites. Here we discuss recent findings which have shed light on the battle over metabolites between T. gondii and its host.
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61
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Nyonda MA, Hammoudi PM, Ye S, Maire J, Marq JB, Yamamoto M, Soldati-Favre D. Toxoplasma gondii GRA60 is an effector protein that modulates host cell autonomous immunity and contributes to virulence. Cell Microbiol 2020; 23:e13278. [PMID: 33040458 DOI: 10.1111/cmi.13278] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/04/2020] [Accepted: 10/08/2020] [Indexed: 02/06/2023]
Abstract
Toxoplasma gondii infects virtually any nucleated cell and resides inside a non-phagocytic vacuole surrounded by a parasitophorous vacuolar membrane (PVM). Pivotal to the restriction of T. gondii dissemination upon infection in murine cells is the recruitment of immunity regulated GTPases (IRGs) and guanylate binding proteins (GBPs) to the PVM that leads to pathogen elimination. The virulent T. gondii type I RH strain secretes a handful of effectors including the dense granule protein GRA7, the serine-threonine kinases ROP17 and ROP18, and a pseudo-kinase ROP5, that synergistically inhibit the recruitment of IRGs to the PVM. Here, we characterise GRA60, a novel dense granule effector, which localises to the vacuolar space and PVM and contributes to virulence of RH in mice, suggesting a role in the subversion of host cell defence mechanisms. Members of the host cell IRG defence system Irgb10 and Irga6 are recruited to the PVM of RH parasites lacking GRA60 as observed previously for the avirulent RHΔrop5 mutant, with RH preventing such recruitment. Deletion of GRA60 in RHΔrop5 leads to a recruitment of IRGs comparable to the single knockouts. GRA60 therefore represents a novel parasite effector conferring resistance to IRGs in type I parasites, and found associated to ROP18, a member of the virulence complex.
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Affiliation(s)
- Mary Akinyi Nyonda
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Pierre-Mehdi Hammoudi
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Shu Ye
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Jessica Maire
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Division of Infectious Diseases, Osaka University, Suita, Japan
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
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62
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Plasmodium falciparum Apicomplexan-Specific Glucosamine-6-Phosphate N-Acetyltransferase Is Key for Amino Sugar Metabolism and Asexual Blood Stage Development. mBio 2020; 11:mBio.02045-20. [PMID: 33082260 PMCID: PMC7587441 DOI: 10.1128/mbio.02045-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Apicomplexan parasites cause a major burden on global health and economy. The absence of treatments, the emergence of resistances against available therapies, and the parasite’s ability to manipulate host cells and evade immune systems highlight the urgent need to characterize new drug targets to treat infections caused by these parasites. We demonstrate that glucosamine-6-phosphate N-acetyltransferase (GNA1), required for the biosynthesis of UDP-N-acetylglucosamine (UDP-GlcNAc), is essential for P. falciparum asexual blood stage development and that the disruption of the gene encoding this enzyme quickly causes the death of the parasite within a life cycle. The high-resolution crystal structure of the GNA1 ortholog from the apicomplexan parasite C. parvum, used here as a surrogate, highlights significant differences from human GNA1. These divergences can be exploited for the design of specific inhibitors against the malaria parasite. UDP-N-acetylglucosamine (UDP-GlcNAc), the main product of the hexosamine biosynthetic pathway, is an important metabolite in protozoan parasites since its sugar moiety is incorporated into glycosylphosphatidylinositol (GPI) glycolipids and N- and O-linked glycans. Apicomplexan parasites have a hexosamine pathway comparable to other eukaryotic organisms, with the exception of the glucosamine-phosphate N-acetyltransferase (GNA1) enzymatic step that has an independent evolutionary origin and significant differences from nonapicomplexan GNA1s. By using conditional genetic engineering, we demonstrate the requirement of GNA1 for the generation of a pool of UDP-GlcNAc and for the development of intraerythrocytic asexual Plasmodium falciparum parasites. Furthermore, we present the 1.95 Å resolution structure of the GNA1 ortholog from Cryptosporidium parvum, an apicomplexan parasite which is a leading cause of diarrhea in developing countries, as a surrogate for P. falciparum GNA1. The in-depth analysis of the crystal shows the presence of specific residues relevant for GNA1 enzymatic activity that are further investigated by the creation of site-specific mutants. The experiments reveal distinct features in apicomplexan GNA1 enzymes that could be exploitable for the generation of selective inhibitors against these parasites, by targeting the hexosamine pathway. This work underscores the potential of apicomplexan GNA1 as a drug target against malaria.
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63
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Sinai AP, Suvorova ES. The RESTRICTION checkpoint: a window of opportunity governing developmental transitions in Toxoplasma gondii. Curr Opin Microbiol 2020; 58:99-105. [PMID: 33065371 DOI: 10.1016/j.mib.2020.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 01/27/2023]
Abstract
The life cycle of Toxoplasma gondii is characterized by active replication alternating with periods of rest. Encysted dormant sporozoites and bradyzoites initiate active replication as tachyzoites and merozoites. Here we explore the role of the cell cycle with a focus on the canonical G1 RESTRICTION checkpoint (R-point) as the integrator governing developmental decisions in T. gondii. This surveillance mechanism, which licenses replication, creates a window of opportunity in G1 for cellular reorganization in the execution of developmental transitions. We also explore the unique status of the bradyzoite, the only life cycle stage executing both a forward (entry into the sexual cycle) and reverse (recrudescence) developmental transitions as a multipotent cell. These opposing decisions are executed through the common machinery of the RESTRICTION checkpoint.
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Affiliation(s)
- Anthony P Sinai
- Department of Microbiology Immunology and Molecular Genetics, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536, USA
| | - Elena S Suvorova
- Department of Internal Medicine, Division of Infectious Diseases and International Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Blvd, Tampa, FL 33612, USA.
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64
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Harding CR, Sidik SM, Petrova B, Gnädig NF, Okombo J, Herneisen AL, Ward KE, Markus BM, Boydston EA, Fidock DA, Lourido S. Genetic screens reveal a central role for heme metabolism in artemisinin susceptibility. Nat Commun 2020; 11:4813. [PMID: 32968076 PMCID: PMC7511413 DOI: 10.1038/s41467-020-18624-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/03/2020] [Indexed: 01/26/2023] Open
Abstract
Artemisinins have revolutionized the treatment of Plasmodium falciparum malaria; however, resistance threatens to undermine global control efforts. To broadly explore artemisinin susceptibility in apicomplexan parasites, we employ genome-scale CRISPR screens recently developed for Toxoplasma gondii to discover sensitizing and desensitizing mutations. Using a sublethal concentration of dihydroartemisinin (DHA), we uncover the putative transporter Tmem14c whose disruption increases DHA susceptibility. Screens performed under high doses of DHA provide evidence that mitochondrial metabolism can modulate resistance. We show that disrupting a top candidate from the screens, the mitochondrial protease DegP2, lowers porphyrin levels and decreases DHA susceptibility, without significantly altering parasite fitness in culture. Deleting the homologous gene in P. falciparum, PfDegP, similarly lowers heme levels and DHA susceptibility. These results expose the vulnerability of heme metabolism to genetic perturbations that can lead to increased survival in the presence of DHA.
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Affiliation(s)
- Clare R Harding
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, UK
| | - Saima M Sidik
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Boryana Petrova
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Nina F Gnädig
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - John Okombo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | | | - Kurt E Ward
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Benedikt M Markus
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, USA
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Sharma J, Rodriguez P, Roy P, Guiton PS. Transcriptional ups and downs: patterns of gene expression in the life cycle of Toxoplasma gondii. Microbes Infect 2020; 22:525-533. [PMID: 32931908 DOI: 10.1016/j.micinf.2020.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/22/2022]
Abstract
Toxoplasma gondii reproduces sexually in felines and asexually in virtually all warm-blooded animals, including humans. This obligate intracellular parasite alternates between biologically distinct developmental stages throughout its complex life cycle. Stage conversion is crucial for T. gondii transmission, persistence, and the maintenance of genetic diversity within the species. Genome-wide comparative transcriptomic studies have contributed invaluable insights into the regulatory gene networks underlying T. gondii development.
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Affiliation(s)
- Janak Sharma
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA
| | - Paula Rodriguez
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA
| | - Proyasha Roy
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA
| | - Pascale S Guiton
- Department of Biological Sciences, California State University East Bay, Hayward, CA, USA.
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66
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Swift RP, Rajaram K, Keutcha C, Liu HB, Kwan B, Dziedzic A, Jedlicka AE, Prigge ST. The NTP generating activity of pyruvate kinase II is critical for apicoplast maintenance in Plasmodium falciparum. eLife 2020; 9:e50807. [PMID: 32815516 PMCID: PMC7556864 DOI: 10.7554/elife.50807] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 08/20/2020] [Indexed: 12/20/2022] Open
Abstract
The apicoplast of Plasmodium falciparum parasites is believed to rely on the import of three-carbon phosphate compounds for use in organelle anabolic pathways, in addition to the generation of energy and reducing power within the organelle. We generated a series of genetic deletions in an apicoplast metabolic bypass line to determine which genes involved in apicoplast carbon metabolism are required for blood-stage parasite survival and organelle maintenance. We found that pyruvate kinase II (PyrKII) is essential for organelle maintenance, but that production of pyruvate by PyrKII is not responsible for this phenomenon. Enzymatic characterization of PyrKII revealed activity against all NDPs and dNDPs tested, suggesting that it may be capable of generating a broad range of nucleotide triphosphates. Conditional mislocalization of PyrKII resulted in decreased transcript levels within the apicoplast that preceded organelle disruption, suggesting that PyrKII is required for organelle maintenance due to its role in nucleotide triphosphate generation.
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Affiliation(s)
- Russell P Swift
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Krithika Rajaram
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Cyrianne Keutcha
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Hans B Liu
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Bobby Kwan
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Amanda Dziedzic
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Anne E Jedlicka
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
| | - Sean T Prigge
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public HealthBaltimoreUnited States
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67
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Kloehn J, Harding CR, Soldati-Favre D. Supply and demand-heme synthesis, salvage and utilization by Apicomplexa. FEBS J 2020; 288:382-404. [PMID: 32530125 DOI: 10.1111/febs.15445] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 05/23/2020] [Accepted: 06/05/2020] [Indexed: 01/05/2023]
Abstract
The Apicomplexa phylum groups important human and animal pathogens that cause severe diseases, encompassing malaria, toxoplasmosis, and cryptosporidiosis. In common with most organisms, apicomplexans rely on heme as cofactor for several enzymes, including cytochromes of the electron transport chain. This heme derives from de novo synthesis and/or the development of uptake mechanisms to scavenge heme from their host. Recent studies have revealed that heme synthesis is essential for Toxoplasma gondii tachyzoites, as well as for the mosquito and liver stages of Plasmodium spp. In contrast, the erythrocytic stages of the malaria parasites rely on scavenging heme from the host red blood cell. The unusual heme synthesis pathway in Apicomplexa spans three cellular compartments and comprises enzymes of distinct ancestral origin, providing promising drug targets. Remarkably given the requirement for heme, T. gondii can tolerate the loss of several heme synthesis enzymes at a high fitness cost, while the ferrochelatase is essential for survival. These findings indicate that T. gondii is capable of salvaging heme precursors from its host. Furthermore, heme is implicated in the activation of the key antimalarial drug artemisinin. Recent findings established that a reduction in heme availability corresponds to decreased sensitivity to artemisinin in T. gondii and Plasmodium falciparum, providing insights into the possible development of combination therapies to tackle apicomplexan parasites. This review describes the microeconomics of heme in Apicomplexa, from supply, either from de novo synthesis or scavenging, to demand by metabolic pathways, including the electron transport chain.
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Affiliation(s)
- Joachim Kloehn
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Switzerland
| | - Clare R Harding
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, UK
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Kloehn J, Oppenheim RD, Siddiqui G, De Bock PJ, Kumar Dogga S, Coute Y, Hakimi MA, Creek DJ, Soldati-Favre D. Multi-omics analysis delineates the distinct functions of sub-cellular acetyl-CoA pools in Toxoplasma gondii. BMC Biol 2020; 18:67. [PMID: 32546260 PMCID: PMC7296777 DOI: 10.1186/s12915-020-00791-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/08/2020] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Acetyl-CoA is a key molecule in all organisms, implicated in several metabolic pathways as well as in transcriptional regulation and post-translational modification. The human pathogen Toxoplasma gondii possesses at least four enzymes which generate acetyl-CoA in the nucleo-cytosol (acetyl-CoA synthetase (ACS); ATP citrate lyase (ACL)), mitochondrion (branched-chain α-keto acid dehydrogenase-complex (BCKDH)) and apicoplast (pyruvate dehydrogenase complex (PDH)). Given the diverse functions of acetyl-CoA, we know very little about the role of sub-cellular acetyl-CoA pools in parasite physiology. RESULTS To assess the importance and functions of sub-cellular acetyl-CoA-pools, we measured the acetylome, transcriptome, proteome and metabolome of parasites lacking ACL/ACS or BCKDH. We demonstrate that ACL/ACS constitute a synthetic lethal pair. Loss of both enzymes causes a halt in fatty acid elongation, hypo-acetylation of nucleo-cytosolic and secretory proteins and broad changes in gene expression. In contrast, loss of BCKDH results in an altered TCA cycle, hypo-acetylation of mitochondrial proteins and few specific changes in gene expression. We provide evidence that changes in the acetylome, transcriptome and proteome of cells lacking BCKDH enable the metabolic adaptations and thus the survival of these parasites. CONCLUSIONS Using multi-omics and molecular tools, we obtain a global and integrative picture of the role of distinct acetyl-CoA pools in T. gondii physiology. Cytosolic acetyl-CoA is essential and is required for the synthesis of parasite-specific fatty acids. In contrast, loss of mitochondrial acetyl-CoA can be compensated for through metabolic adaptations implemented at the transcriptional, translational and post-translational level.
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Affiliation(s)
- Joachim Kloehn
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Rebecca D Oppenheim
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Ghizal Siddiqui
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville campus, Parkville, VIC, 3052, Australia
| | - Pieter-Jan De Bock
- University Grenoble Alpes, CEA, INSERM, IRIG, BGE, F-38000, Grenoble, France
| | - Sunil Kumar Dogga
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland
| | - Yohann Coute
- University Grenoble Alpes, CEA, INSERM, IRIG, BGE, F-38000, Grenoble, France
| | - Mohamed-Ali Hakimi
- Epigenetic and Parasites Team, UMR5163/LAPM, Domaine de la Merci, Jean Roget Institute, 38700, La Tronche, France
| | - Darren J Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville campus, Parkville, VIC, 3052, Australia
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Rue Michel-Servet 1, 1211, Geneva, Switzerland.
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69
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Bergmann A, Floyd K, Key M, Dameron C, Rees KC, Thornton LB, Whitehead DC, Hamza I, Dou Z. Toxoplasma gondii requires its plant-like heme biosynthesis pathway for infection. PLoS Pathog 2020; 16:e1008499. [PMID: 32407406 PMCID: PMC7252677 DOI: 10.1371/journal.ppat.1008499] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 05/27/2020] [Accepted: 03/25/2020] [Indexed: 01/21/2023] Open
Abstract
Heme, an iron-containing organic ring, is essential for virtually all living organisms by serving as a prosthetic group in proteins that function in diverse cellular activities ranging from diatomic gas transport and sensing, to mitochondrial respiration, to detoxification. Cellular heme levels in microbial pathogens can be a composite of endogenous de novo synthesis or exogenous uptake of heme or heme synthesis intermediates. Intracellular pathogenic microbes switch routes for heme supply when heme availability fluctuates in their replicative environment throughout infection. Here, we show that Toxoplasma gondii, an obligate intracellular human pathogen, encodes a functional heme biosynthesis pathway. A chloroplast-derived organelle, termed apicoplast, is involved in heme production. Genetic and chemical manipulation revealed that de novo heme production is essential for T. gondii intracellular growth and pathogenesis. Surprisingly, the herbicide oxadiazon significantly impaired Toxoplasma growth, consistent with phylogenetic analyses that show T. gondii protoporphyrinogen oxidase is more closely related to plants than mammals. This inhibition can be enhanced by 15- to 25-fold with two oxadiazon derivatives, lending therapeutic proof that Toxoplasma heme biosynthesis is a druggable target. As T. gondii has been used to model other apicomplexan parasites, our study underscores the utility of targeting heme biosynthesis in other pathogenic apicomplexans, such as Plasmodium spp., Cystoisospora, Eimeria, Neospora, and Sarcocystis.
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Affiliation(s)
- Amy Bergmann
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Katherine Floyd
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Melanie Key
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Carly Dameron
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Kerrick C. Rees
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - L. Brock Thornton
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Daniel C. Whitehead
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, United States of America
| | - Iqbal Hamza
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States of America
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, United States of America
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70
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Liang X, Cui J, Yang X, Xia N, Li Y, Zhao J, Gupta N, Shen B. Acquisition of exogenous fatty acids renders apicoplast-based biosynthesis dispensable in tachyzoites of Toxoplasma. J Biol Chem 2020; 295:7743-7752. [PMID: 32341123 DOI: 10.1074/jbc.ra120.013004] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/08/2020] [Indexed: 12/20/2022] Open
Abstract
Toxoplasma gondii is a common protozoan parasite that infects a wide range of hosts, including livestock and humans. Previous studies have suggested that the type 2 fatty acid synthesis (FAS2) pathway, located in the apicoplast (a nonphotosynthetic plastid relict), is crucial for the parasite's survival. Here we examined the physiological relevance of fatty acid synthesis in T. gondii by focusing on the pyruvate dehydrogenase complex and malonyl-CoA-[acyl carrier protein] transacylase (FabD), which are located in the apicoplast to drive de novo fatty acid biosynthesis. Our results disclosed unexpected metabolic resilience of T. gondii tachyzoites, revealing that they can tolerate CRISPR/Cas9-assisted genetic deletions of three pyruvate dehydrogenase subunits or FabD. All mutants were fully viable in prolonged cultures, albeit with impaired growth and concurrent loss of the apicoplast. Even more surprisingly, these mutants displayed normal virulence in mice, suggesting an expendable role of the FAS2 pathway in vivo Metabolic labeling of the Δpdh-e1α mutant showed reduced incorporation of glucose-derived carbon into fatty acids with medium chain lengths (C14:0 and C16:0), revealing that FAS2 activity was indeed compromised. Moreover, supplementation of exogenous C14:0 or C16:0 significantly reversed the growth defect in the Δpdh-e1α mutant, indicating salvage of these fatty acids. Together, these results demonstrate that the FAS2 pathway is dispensable during the lytic cycle of Toxoplasma because of its remarkable flexibility in acquiring fatty acids. Our findings question the long-held assumption that targeting this pathway has significant therapeutic potential for managing Toxoplasma infections.
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Affiliation(s)
- Xiaohan Liang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China
| | - Jianmin Cui
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China
| | - Xuke Yang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China
| | - Ningbo Xia
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China
| | - Yaqiong Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China
| | - Junlong Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China.,Key Laboratory of Preventive Medicine in Hubei Province, Wuhan, Hubei Province, People's Republic of China.,Hubei Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei Province, People's Republic of China
| | - Nishith Gupta
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China .,Department of Molecular Parasitology, Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Bang Shen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei Province, People's Republic of China .,Key Laboratory of Preventive Medicine in Hubei Province, Wuhan, Hubei Province, People's Republic of China
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71
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Kim K. An Omnivore's Dilemma: Toxoplasma gondii's Flexible Metabolic Networks. Trends Parasitol 2020; 36:408-410. [PMID: 32298627 DOI: 10.1016/j.pt.2020.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Abstract
Host cells provide protection from the environment for intracellular pathogens, but acquisition of nutrients and sensing of changes in the host cell bring new challenges. Krishnan et al. have recently developed a comprehensive genome-scale metabolic model (GEM) of the Toxoplasma gondii metabolic network that incorporates genetic, transcriptomic, and metabolomic data.
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Affiliation(s)
- Kami Kim
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
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72
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The Bradyzoite: A Key Developmental Stage for the Persistence and Pathogenesis of Toxoplasmosis. Pathogens 2020; 9:pathogens9030234. [PMID: 32245165 PMCID: PMC7157559 DOI: 10.3390/pathogens9030234] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/18/2020] [Accepted: 03/19/2020] [Indexed: 12/19/2022] Open
Abstract
Toxoplasma gondii is a ubiquitous parasitic protist found in a wide variety of hosts, including a large proportion of the human population. Beyond an acute phase which is generally self-limited in immunocompetent individuals, the ability of the parasite to persist as a dormant stage, called bradyzoite, is an important aspect of toxoplasmosis. Not only is this stage not eliminated by current treatments, but it can also reactivate in immunocompromised hosts, leading to a potentially fatal outcome. Yet, despite its critical role in the pathology, the bradyzoite stage is relatively understudied. One main explanation is that it is a considerably challenging model, which essentially has to be derived from in vivo sources. However, recent progress on genetic manipulation and in vitro differentiation models now offers interesting perspectives for tackling key biological questions related to this particularly important developmental stage.
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