1
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Ovciarikova J, Shikha S, Lacombe A, Courjol F, McCrone R, Hussain W, Maclean A, Lemgruber L, Martins-Duarte ES, Gissot M, Sheiner L. Two ancient membrane pores mediate mitochondrial-nucleus membrane contact sites. J Cell Biol 2024; 223:e202304075. [PMID: 38456969 PMCID: PMC10923651 DOI: 10.1083/jcb.202304075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 11/28/2023] [Accepted: 01/29/2024] [Indexed: 03/09/2024] Open
Abstract
Coordination between nucleus and mitochondria is essential for cell survival, and thus numerous communication routes have been established between these two organelles over eukaryotic cell evolution. One route for organelle communication is via membrane contact sites, functional appositions formed by molecular tethers. We describe a novel nuclear-mitochondrial membrane contact site in the protozoan Toxoplasma gondii. We have identified specific contacts occurring at the nuclear pore and demonstrated an interaction between components of the nuclear pore and the mitochondrial protein translocon, highlighting them as molecular tethers. Genetic disruption of the nuclear pore or the TOM translocon components, TgNup503 or TgTom40, respectively, result in contact site reduction, supporting their potential involvement in this tether. TgNup503 depletion further leads to specific mitochondrial morphology and functional defects, supporting a role for nuclear-mitochondrial contacts in mediating their communication. The discovery of a contact formed through interaction between two ancient mitochondrial and nuclear complexes sets the ground for better understanding of mitochondrial-nuclear crosstalk in eukaryotes.
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Affiliation(s)
- Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Shikha Shikha
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Alice Lacombe
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Flavie Courjol
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019—UMR 9017—CIIL—Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Rosalind McCrone
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Wasim Hussain
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Andrew Maclean
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Leandro Lemgruber
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Erica S. Martins-Duarte
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mathieu Gissot
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019—UMR 9017—CIIL—Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
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2
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Ovciarikova J, Oliveira Souza RO, Arrizabalaga G, Sheiner L. Protein control of membrane and organelle dynamics: Insights from the divergent eukaryote Toxoplasma gondii. Curr Opin Cell Biol 2022; 76:102085. [PMID: 35569259 PMCID: PMC9586877 DOI: 10.1016/j.ceb.2022.102085] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/28/2022] [Accepted: 04/01/2022] [Indexed: 11/26/2022]
Abstract
Integral membrane protein complexes control key cellular functions in eukaryotes by defining membrane-bound spaces within organelles and mediating inter-organelles contacts. Despite the critical role of membrane complexes in cell biology, most of our knowledge is from a handful of model systems, primarily yeast and mammals, while a full functional and evolutionary understanding remains incomplete without the perspective from a broad range of divergent organisms. Apicomplexan parasites are single-cell eukaryotes whose survival depends on organelle compartmentalisation and communication. Studies of a model apicomplexan, Toxoplasma gondii, reveal unexpected divergence in the composition and function of complexes previously considered broadly conserved, such as the mitochondrial ATP synthase and the tethers mediating ER–mitochondria membrane contact sites. Thus, Toxoplasma joins the repertoire of divergent model eukaryotes whose research completes our understanding of fundamental cell biology.
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3
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Ovciarikova J, Shikha S, Sheiner L. Nuclear Interactions: A Spotlight on Nuclear Mitochondrial Membrane Contact Sites. Contact (Thousand Oaks) 2022; 5:25152564221096217. [PMID: 36338149 PMCID: PMC9623421 DOI: 10.1177/25152564221096217] [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] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Membrane contact sites (MCS) are critical for cellular functions of eukaryotes, as they enable communication and exchange between organelles. Research over the last decade unravelled the function and composition of MCS between a variety of organelles including mitochondria, ER, plasma membrane, lysosomes, lipid droplets, peroxisome and endosome, to name a few. In fact, MCS are found between any pair of organelles studied to date, with common functions including lipid exchange, calcium signalling and organelle positioning in the cell. Work in the past year has started addressing the composition and function of nuclear-mitochondrial MCS. Tether components mediating these contacts in yeast have been identified via comprehensive phenotypic screens, which also revealed a possible link between this contact and phosphatidylcholine metabolism. In human cells, and in the protozoan parasites causing malaria, proximity between these organelles is proposed to promote cell survival via a mitochondrial retrograde response. These pioneering studies should inspire the field to explore what cellular processes depend on the exchange between the nucleus and the mitochondrion, given that they play such central roles in cell biology.
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Affiliation(s)
- Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, UK
| | - Shikha Shikha
- Wellcome Centre for Integrative Parasitology, University of Glasgow, UK
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, UK
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4
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Mallo N, Ovciarikova J, Martins-Duarte ES, Baehr SC, Biddau M, Wilde ML, Uboldi AD, Lemgruber L, Tonkin CJ, Wideman JG, Harding CR, Sheiner L. Depletion of a Toxoplasma porin leads to defects in mitochondrial morphology and contacts with the endoplasmic reticulum. J Cell Sci 2021; 134:272536. [PMID: 34523684 PMCID: PMC8572010 DOI: 10.1242/jcs.255299] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 09/06/2021] [Indexed: 01/21/2023] Open
Abstract
The voltage-dependent anion channel (VDAC) is a ubiquitous channel in the outer membrane of the mitochondrion with multiple roles in protein, metabolite and small molecule transport. In mammalian cells, VDAC protein, as part of a larger complex including the inositol triphosphate receptor, has been shown to have a role in mediating contacts between the mitochondria and endoplasmic reticulum (ER). We identify VDAC of the pathogenic apicomplexan Toxoplasma gondii and demonstrate its importance for parasite growth. We show that VDAC is involved in protein import and metabolite transfer to mitochondria. Further, depletion of VDAC resulted in significant morphological changes in the mitochondrion and ER, suggesting a role in mediating contacts between these organelles in T. gondii. This article has an associated First Person interview with the first author of the paper. Summary: Depletion of the Toxoplasma voltage-dependent anion channel highlights the importance of endoplasmic reticulum–mitochondria membrane contact sites in maintaining organelle morphology.
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Affiliation(s)
- Natalia Mallo
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Erica S Martins-Duarte
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 486 31270-901, Brazil
| | - Stephan C Baehr
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Marco Biddau
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Mary-Louise Wilde
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3086, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Alessandro D Uboldi
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3086, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Leandro Lemgruber
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK.,Glasgow Imaging Facility, University of Glasgow, Glasgow G12 8TA, UK
| | - Christopher J Tonkin
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC 3086, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jeremy G Wideman
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Clare R Harding
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow G12 8TA, UK
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5
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Maclean AE, Bridges HR, Silva MF, Ding S, Ovciarikova J, Hirst J, Sheiner L. Complexome profile of Toxoplasma gondii mitochondria identifies divergent subunits of respiratory chain complexes including new subunits of cytochrome bc1 complex. PLoS Pathog 2021; 17:e1009301. [PMID: 33651838 PMCID: PMC7987180 DOI: 10.1371/journal.ppat.1009301] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [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: 08/18/2020] [Revised: 03/23/2021] [Accepted: 01/11/2021] [Indexed: 12/30/2022] Open
Abstract
The mitochondrial electron transport chain (mETC) and F1Fo-ATP synthase are of central importance for energy and metabolism in eukaryotic cells. The Apicomplexa, important pathogens of humans causing diseases such as toxoplasmosis and malaria, depend on their mETC in every known stage of their complicated life cycles. Here, using a complexome profiling proteomic approach, we have characterised the Toxoplasma mETC complexes and F1Fo-ATP synthase. We identified and assigned 60 proteins to complexes II, IV and F1Fo-ATP synthase of Toxoplasma, of which 16 have not been identified previously. Notably, our complexome profile elucidates the composition of the Toxoplasma complex III, the target of clinically used drugs such as atovaquone. We identified two new homologous subunits and two new parasite-specific subunits, one of which is broadly conserved in myzozoans. We demonstrate all four proteins are essential for complex III stability and parasite growth, and show their depletion leads to decreased mitochondrial potential, supporting their assignment as complex III subunits. Our study highlights the divergent subunit composition of the apicomplexan mETC and F1Fo-ATP synthase complexes and sets the stage for future structural and drug discovery studies.
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Affiliation(s)
- Andrew E. Maclean
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, United Kingdom
| | - Hannah R. Bridges
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Mariana F. Silva
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, United Kingdom
- Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
| | - Shujing Ding
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, United Kingdom
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, United Kingdom
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6
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Mühleip A, Kock Flygaard R, Ovciarikova J, Lacombe A, Fernandes P, Sheiner L, Amunts A. ATP synthase hexamer assemblies shape cristae of Toxoplasma mitochondria. Nat Commun 2021; 12:120. [PMID: 33402698 PMCID: PMC7785744 DOI: 10.1038/s41467-020-20381-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/30/2020] [Indexed: 01/29/2023] Open
Abstract
Mitochondrial ATP synthase plays a key role in inducing membrane curvature to establish cristae. In Apicomplexa causing diseases such as malaria and toxoplasmosis, an unusual cristae morphology has been observed, but its structural basis is unknown. Here, we report that the apicomplexan ATP synthase assembles into cyclic hexamers, essential to shape their distinct cristae. Cryo-EM was used to determine the structure of the hexamer, which is held together by interactions between parasite-specific subunits in the lumenal region. Overall, we identified 17 apicomplexan-specific subunits, and a minimal and nuclear-encoded subunit-a. The hexamer consists of three dimers with an extensive dimer interface that includes bound cardiolipins and the inhibitor IF1. Cryo-ET and subtomogram averaging revealed that hexamers arrange into ~20-megadalton pentagonal pyramids in the curved apical membrane regions. Knockout of the linker protein ATPTG11 resulted in the loss of pentagonal pyramids with concomitant aberrantly shaped cristae. Together, this demonstrates that the unique macromolecular arrangement is critical for the maintenance of cristae morphology in Apicomplexa.
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Affiliation(s)
- Alexander Mühleip
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
| | - Rasmus Kock Flygaard
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
| | - Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Alice Lacombe
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Paula Fernandes
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK.
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden.
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden.
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7
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Lacombe A, Maclean AE, Ovciarikova J, Tottey J, Mühleip A, Fernandes P, Sheiner L. Identification of the
Toxoplasma gondii
mitochondrial ribosome, and characterisation of a protein essential for mitochondrial translation. Mol Microbiol 2019; 112:1235-1252. [PMID: 31339607 PMCID: PMC6851545 DOI: 10.1111/mmi.14357] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2019] [Indexed: 01/20/2023]
Abstract
Apicomplexan parasites cause diseases such as malaria and toxoplasmosis. The apicomplexan mitochondrion shows striking differences from common model organisms, including fundamental processes such as mitochondrial translation. Despite evidence that mitochondrial translation is essential for parasite survival, it is largely understudied. Progress has been restricted by the absence of functional assays to detect apicomplexan mitochondrial translation, a lack of knowledge of proteins involved in the process and the inability to identify and detect mitoribosomes. We report the localization of 12 new mitochondrial proteins, including 6 putative mitoribosomal proteins. We demonstrate the integration of three mitoribosomal proteins in macromolecular complexes, and provide evidence suggesting these are apicomplexan mitoribosomal subunits, detected here for the first time. Finally, a new analytical pipeline detected defects in mitochondrial translation upon depletion of the small subunit protein 35 (TgmS35), while other mitochondrial functions remain unaffected. Our work lays a foundation for the study of apicomplexan mitochondrial translation.
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Affiliation(s)
- Alice Lacombe
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
| | - Andrew E. Maclean
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
| | - Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
| | - Julie Tottey
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
- UMR 1282 ISP INRA‐Université François Rabelais de Tours Nouzilly France
| | - Alexander Mühleip
- Department of Biochemistry and Biophysics Stockholm University Stockholm Sweden
| | - Paula Fernandes
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology University of Glasgow 120 University Place GlasgowG12 8TAUK
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8
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Findlay EG, Currie AJ, Zhang A, Ovciarikova J, Young L, Stevens H, McHugh BJ, Canel M, Gray M, Milling SWF, Campbell JDM, Savill J, Serrels A, Davidson DJ. Exposure to the antimicrobial peptide LL-37 produces dendritic cells optimized for immunotherapy. Oncoimmunology 2019; 8:1608106. [PMID: 31413918 PMCID: PMC6682359 DOI: 10.1080/2162402x.2019.1608106] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 03/13/2019] [Indexed: 12/14/2022] Open
Abstract
Immunization of patients with autologous, ex vivo matured dendritic cell (DC) preparations, in order to prime antitumor T-cell responses, is the focus of intense research. Despite progress and approval of clinical approaches, significant enhancement of these personalized immunotherapies is urgently needed to improve efficacy. We show that immunotherapeutic murine and human DC, generated in the presence of the antimicrobial host defense peptide LL-37, have dramatically enhanced expansion and differentiation of cells with key features of the critical CD103+/CD141+ DC subsets, including enhanced cross-presentation and co-stimulatory capacity, and upregulation of CCR7 with improved migratory capacity. These LL-37-DC enhanced proliferation, activation and cytokine production by CD8+ (but not CD4+) T cells in vitro and in vivo. Critically, tumor antigen-presenting LL-37-DC increased migration of primed, activated CD8+ T cells into established squamous cell carcinomas in mice, and resulted in tumor regression. This advance therefore has the potential to dramatically enhance DC immunotherapy protocols.
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Affiliation(s)
- Emily Gwyer Findlay
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Andrew J Currie
- School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia
| | - Ailiang Zhang
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Jana Ovciarikova
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Lisa Young
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Holly Stevens
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Brian J McHugh
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Marta Canel
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Mohini Gray
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Simon W F Milling
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - John D M Campbell
- Scottish National Blood Transfusion Service, Heriot Watt Research Park, Edinburgh, UK
| | - John Savill
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Alan Serrels
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
| | - Donald J Davidson
- University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK.,School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia
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9
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Biddau M, Bouchut A, Major J, Saveria T, Tottey J, Oka O, van-Lith M, Jennings KE, Ovciarikova J, DeRocher A, Striepen B, Waller RF, Parsons M, Sheiner L. Two essential Thioredoxins mediate apicoplast biogenesis, protein import, and gene expression in Toxoplasma gondii. PLoS Pathog 2018; 14:e1006836. [PMID: 29470517 PMCID: PMC5823475 DOI: 10.1371/journal.ppat.1006836] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/21/2017] [Indexed: 11/19/2022] Open
Abstract
Apicomplexan parasites are global killers, being the causative agents of diseases like toxoplasmosis and malaria. These parasites are known to be hypersensitive to redox imbalance, yet little is understood about the cellular roles of their various redox regulators. The apicoplast, an essential plastid organelle, is a verified apicomplexan drug target. Nuclear-encoded apicoplast proteins traffic through the ER and multiple apicoplast sub-compartments to their place of function. We propose that thioredoxins contribute to the control of protein trafficking and of protein function within these apicoplast compartments. We studied the role of two Toxoplasma gondiiapicoplast thioredoxins (TgATrx), both essential for parasite survival. By describing the cellular phenotypes of the conditional depletion of either of these redox regulated enzymes we show that each of them contributes to a different apicoplast biogenesis pathway. We provide evidence for TgATrx1’s involvement in ER to apicoplast trafficking and TgATrx2 in the control of apicoplast gene expression components. Substrate pull-down further recognizes gene expression factors that interact with TgATrx2. We use genetic complementation to demonstrate that the function of both TgATrxs is dependent on their disulphide exchange activity. Finally, TgATrx2 is divergent from human thioredoxins. We demonstrate its activity in vitro thus providing scope for drug screening. Our study represents the first functional characterization of thioredoxins in Toxoplasma, highlights the importance of redox regulation of apicoplast functions and provides new tools to study redox biology in these parasites. To survive, apicomplexan parasites must adjust to the redox insults they experience. These parasites undergo redox stresses induced by the host cell within which they live, by the host immune system, and by their own metabolic activities. Yet the myriad of cellular processes that are affected by redox changes and that may take part in maintaining the redox balance within the parasite are largely understudied. Thioredoxins are enzymes that link the redox state of subcellular environments to the functional state or the cellular trafficking of their substrate proteins. In this work, we identify two pathways that are controlled by two thioredoxins in the apicomplexan Toxoplasma gondii, and demonstrate that both are essential for parasite survival. We show that each of these enzymes contributes to the function of the apicomplexan plastid, the apicoplast, a unique parasite organelle with importance for drug discovery efforts. We thus highlight that part of the apicomplexan sensitivity to redox imbalance is specifically related to the apicoplast, and point at the importance of thioredoxins in mediating apicoplast biogenesis. Finally, our work raises the potential of apicoplast thioredoxins as new drug targets.
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Affiliation(s)
- Marco Biddau
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Anne Bouchut
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Jack Major
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Tracy Saveria
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Julie Tottey
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Ojore Oka
- Institute of Molecular Cell and Systems Biology, Wolfson Link Building, University of Glasgow, Glasgow, United Kingdom
| | - Marcel van-Lith
- Institute of Molecular Cell and Systems Biology, Wolfson Link Building, University of Glasgow, Glasgow, United Kingdom
| | - Katherine Elizabeth Jennings
- Center for Tropical & Emerging Global Diseases, University of Georgia, Brooks Dr. Athens, GA, United States of America
| | - Jana Ovciarikova
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Amy DeRocher
- Center for Infectious Disease Research, Seattle, WA, United States of America
| | - Boris Striepen
- Center for Tropical & Emerging Global Diseases, University of Georgia, Brooks Dr. Athens, GA, United States of America
| | | | - Marilyn Parsons
- Center for Infectious Disease Research, Seattle, WA, United States of America
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Lilach Sheiner
- Wellcome Centre for Molecular Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
- * E-mail:
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10
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Sheiner L, Fellows JD, Ovciarikova J, Brooks CF, Agrawal S, Holmes ZC, Bietz I, Flinner N, Heiny S, Mirus O, Przyborski JM, Striepen B. Toxoplasma gondii Toc75 Functions in Import of Stromal but not Peripheral Apicoplast Proteins. Traffic 2015; 16:1254-69. [PMID: 26381927 DOI: 10.1111/tra.12333] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 09/14/2015] [Accepted: 09/14/2015] [Indexed: 01/09/2023]
Abstract
Apicomplexa are unicellular parasites causing important human and animal diseases, including malaria and toxoplasmosis. Most of these pathogens possess a relict but essential plastid, the apicoplast. The apicoplast was acquired by secondary endosymbiosis between a red alga and a flagellated eukaryotic protist. As a result the apicoplast is surrounded by four membranes. This complex structure necessitates a system of transport signals and translocons allowing nuclear encoded proteins to find their way to specific apicoplast sub-compartments. Previous studies identified translocons traversing two of the four apicoplast membranes. Here we provide functional support for the role of an apicomplexan Toc75 homolog in apicoplast protein transport. We identify two apicomplexan genes encoding Toc75 and Sam50, both members of the Omp85 protein family. We localize the respective proteins to the apicoplast and the mitochondrion of Toxoplasma and Plasmodium. We show that the Toxoplasma Toc75 is essential for parasite growth and that its depletion results in a rapid defect in the import of apicoplast stromal proteins while the import of proteins of the outer compartments is affected only as the secondary consequence of organelle loss. These observations along with the homology to Toc75 suggest a potential role in transport through the second innermost membrane.
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Affiliation(s)
- Lilach Sheiner
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA.,Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Justin D Fellows
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Jana Ovciarikova
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Carrie F Brooks
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Swati Agrawal
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Zachary C Holmes
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
| | - Irine Bietz
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Nadine Flinner
- Molecular Cell Biology of Plants, Biocenter N200, 3. OG, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Sabrina Heiny
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Oliver Mirus
- Molecular Cell Biology of Plants, Biocenter N200, 3. OG, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Jude M Przyborski
- Department of Parasitology, Faculty of Biology, Philipps University Marburg, Marburg, Germany
| | - Boris Striepen
- Center for Tropical and Emerging Global Diseases & Department of Cellular Biology, University of Georgia, 500 D.W. Brooks Drive, Athens, GA, 30602, USA
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