1
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Herneisen AL, Peters ML, Smith TA, Shortt E, Lourido S. SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle. eLife 2024; 13:RP93877. [PMID: 39136687 PMCID: PMC11321763 DOI: 10.7554/elife.93877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024] Open
Abstract
Apicomplexan parasites balance proliferation, persistence, and spread in their metazoan hosts. AGC kinases, such as PKG, PKA, and the PDK1 ortholog SPARK, integrate environmental signals to toggle parasites between replicative and motile life stages. Recent studies have cataloged pathways downstream of apicomplexan PKG and PKA; however, less is known about the global integration of AGC kinase signaling cascades. Here, conditional genetics coupled to unbiased proteomics demonstrates that SPARK complexes with an elongin-like protein to regulate the stability of PKA and PKG in the model apicomplexan Toxoplasma gondii. Defects attributed to SPARK depletion develop after PKG and PKA are down-regulated. Parasites lacking SPARK differentiate into the chronic form of infection, which may arise from reduced activity of a coccidian-specific PKA ortholog. This work delineates the signaling topology of AGC kinases that together control transitions within the asexual cycle of this important family of parasites.
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Affiliation(s)
- Alice L Herneisen
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Michelle L Peters
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Tyler A Smith
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Emily Shortt
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
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2
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Marq JB, Gosetto M, Altenried A, Vadas O, Maco B, Dos Santos Pacheco N, Tosetti N, Soldati-Favre D, Lentini G. Cytokinetic abscission in Toxoplasma gondii is governed by protein phosphatase 2A and the daughter cell scaffold complex. EMBO J 2024:10.1038/s44318-024-00171-9. [PMID: 39009675 DOI: 10.1038/s44318-024-00171-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 06/21/2024] [Accepted: 06/30/2024] [Indexed: 07/17/2024] Open
Abstract
Cytokinetic abscission marks the final stage of cell division, during which the daughter cells physically separate through the generation of new barriers, such as the plasma membrane or cell wall. While the contractile ring plays a central role during cytokinesis in bacteria, fungi and animal cells, the process diverges in Apicomplexa. In Toxoplasma gondii, two daughter cells are formed within the mother cell by endodyogeny. The mechanism by which the progeny cells acquire their plasma membrane during the disassembly of the mother cell, allowing daughter cells to emerge, remains unknown. Here we identify and characterize five T. gondii proteins, including three protein phosphatase 2A subunits, which exhibit a distinct and dynamic localization pattern during parasite division. Individual downregulation of these proteins prevents the accumulation of plasma membrane at the division plane, preventing the completion of cellular abscission. Remarkably, the absence of cytokinetic abscission does not hinder the completion of subsequent division cycles. The resulting progeny are able to egress from the infected cells but fail to glide and invade, except in cases of conjoined twin parasites.
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Affiliation(s)
- Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Margaux Gosetto
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Aline Altenried
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Oscar Vadas
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Bohumil Maco
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | | | - Nicolò Tosetti
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
| | - Gaëlle Lentini
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
- Institute of Cell Biology, University of Bern, Bern, Switzerland.
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3
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Hawkins LM, Wang C, Chaput D, Batra M, Marsilia C, Awshah D, Suvorova ES. The Crk4-Cyc4 complex regulates G 2/M transition in Toxoplasma gondii. EMBO J 2024; 43:2094-2126. [PMID: 38600241 PMCID: PMC11148040 DOI: 10.1038/s44318-024-00095-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/12/2024] [Accepted: 03/26/2024] [Indexed: 04/12/2024] Open
Abstract
A versatile division of apicomplexan parasites and a dearth of conserved regulators have hindered the progress of apicomplexan cell cycle studies. While most apicomplexans divide in a multinuclear fashion, Toxoplasma gondii tachyzoites divide in the traditional binary mode. We previously identified five Toxoplasma CDK-related kinases (Crk). Here, we investigated TgCrk4 and its cyclin partner TgCyc4. We demonstrated that TgCrk4 regulates conventional G2 phase processes, such as repression of chromosome rereplication and centrosome reduplication, and acts upstream of the spindle assembly checkpoint. The spatial TgCyc4 dynamics supported the TgCrk4-TgCyc4 complex role in the coordination of chromosome and centrosome cycles. We also identified a dominant TgCrk4-TgCyc4 complex interactor, TgiRD1 protein, related to DNA replication licensing factor CDT1 but played no role in licensing DNA replication in the G1 phase. Our results showed that TgiRD1 also plays a role in controlling chromosome and centrosome reduplication. Global phosphoproteome analyses identified TgCrk4 substrates, including TgORC4, TgCdc20, TgGCP2, and TgPP2ACA. Importantly, the phylogenetic and structural studies suggest the Crk4-Cyc4 complex is limited to a minor group of the binary dividing apicomplexans.
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Affiliation(s)
- Lauren M Hawkins
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Chengqi Wang
- College of Public Health, University of South Florida, Tampa, FL, 33612, USA
| | - Dale Chaput
- Proteomics Core, College of Arts and Sciences, University of South Florida, Tampa, FL, 33612, USA
| | - Mrinalini Batra
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Clem Marsilia
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Danya Awshah
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Elena S Suvorova
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
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4
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Engelberg K, Bauwens C, Ferguson DJP, Gubbels MJ. Co-dependent formation of the Toxoplasma gondii sub-pellicular microtubules and inner membrane skeleton. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595886. [PMID: 38826480 PMCID: PMC11142238 DOI: 10.1101/2024.05.25.595886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
One of the defining features of apicomplexan parasites is their cytoskeleton composed of alveolar vesicles, known as the inner membrane complex (IMC) undergirded by intermediate-like filament network and an array of subpellicular microtubules (SPMTs). In Toxoplasma gondii, this specialized cytoskeleton is involved in all aspects of the disease-causing lytic cycle, and notably acting as a scaffold for parasite offspring in the internal budding process. Despite advances in our understanding of the architecture and molecular composition, insights pertaining to the coordinated assembly of the scaffold are still largely elusive. Here, T. gondii tachyzoites were dissected by advanced, iterative expansion microscopy (pan-ExM) revealing new insights into the very early sequential formation steps of the tubulin scaffold. A comparative study of the related parasite Sarcocystis neurona revealed that different MT bundling organizations of the nascent SPMTs correlate with the number of central and basal alveolar vesicles. In absence of a so far identified MT nucleation mechanism, we genetically dissected T. gondii γ-tubulin and γ-tubulin complex protein 4 (GCP4). While γ-tubulin depletion abolished the formation of the tubulin scaffold, a set of MTs still formed that suggests SPMTs are nucleated at the outer core of the centrosome. Depletion of GCP4 interfered with the correct assembly of SPMTs into the forming daughter buds, further indicating that the parasite utilizes the γ-tubulin complex in tubulin scaffold formation .
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Affiliation(s)
- Klemens Engelberg
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA
| | - Ciara Bauwens
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA
| | - David J. P. Ferguson
- Department of Biological and Medical Sciences, Oxford Brookes University, and NDCLS, Oxford University, Oxford, United Kingdom
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA
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5
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Pasquarelli RR, Quan JJ, Cheng ES, Yang V, Britton TA, Sha J, Wohlschlegel JA, Bradley PJ. Characterization and functional analysis of Toxoplasma Golgi-associated proteins identified by proximity labelling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.02.578703. [PMID: 38352341 PMCID: PMC10862792 DOI: 10.1101/2024.02.02.578703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Toxoplasma gondii possesses a highly polarized secretory pathway that contains both broadly conserved eukaryotic organelles and unique apicomplexan organelles which play essential roles in the parasite's lytic cycle. As in other eukaryotes, the T. gondii Golgi apparatus sorts and modifies proteins prior to their distribution to downstream organelles. Many of the typical trafficking factors found involved in these processes are missing from apicomplexan genomes, suggesting that these parasites have evolved unique proteins to fill these roles. Here we identify a novel Golgi-localizing protein (ULP1) which contains structural homology to the eukaryotic trafficking factor p115/Uso1. We demonstrate that depletion of ULP1 leads to a dramatic reduction in parasite fitness and replicative ability. Using ULP1 as bait for TurboID proximity labelling and immunoprecipitation, we identify eleven more novel Golgi-associated proteins and demonstrate that ULP1 interacts with the T. gondii COG complex. These proteins include both conserved trafficking factors and parasite-specific proteins. Using a conditional knockdown approach, we assess the effect of each of these eleven proteins on parasite fitness. Together, this work reveals a diverse set of novel T. gondii Golgi-associated proteins that play distinct roles in the secretory pathway. As several of these proteins are absent outside of the Apicomplexa, they represent potential targets for the development of novel therapeutics against these parasites. Importance Apicomplexan parasites such as Toxoplasma gondii infect a large percentage of the world's population and cause substantial human disease. These widespread pathogens use specialized secretory organelles to infect their host cells, modulate host cell functions, and cause disease. While the functions of the secretory organelles are now better understood, the Golgi apparatus of the parasite remains largely unexplored, particularly regarding parasite-specific innovations that may help direct traffic intracellularly. In this work, we characterize ULP1, a protein that is unique to parasites but shares structural similarity to the eukaryotic trafficking factor p115/Uso1. We show that ULP1 plays an important role in parasite replication and demonstrate that it interacts with the conserved oligomeric Golgi (COG) complex. We then use ULP1 proximity labelling to identify eleven additional Golgi-associated proteins which we functionally analyze via conditional knockdown. This work expands our knowledge of the Toxoplasma Golgi apparatus and identifies potential targets for therapeutic intervention.
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Herneisen AL, Peters ML, Smith TA, Shortt E, Lourido S. SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.30.564746. [PMID: 37961644 PMCID: PMC10634940 DOI: 10.1101/2023.10.30.564746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Apicomplexan parasites balance proliferation, persistence, and spread in their metazoan hosts. AGC kinases, such as PKG, PKA, and the PDK1 ortholog SPARK, integrate environmental signals to toggle parasites between replicative and motile life stages. Recent studies have cataloged pathways downstream of apicomplexan PKG and PKA; however, less is known about the global integration of AGC kinase signaling cascades. Here, conditional genetics coupled to unbiased proteomics demonstrates that SPARK complexes with an elongin-like protein to regulate the stability of PKA and PKG in the model apicomplexan Toxoplasma gondii. Defects attributed to SPARK depletion develop after PKG and PKA are down-regulated. Parasites lacking SPARK differentiate into the chronic form of infection, which may arise from reduced activity of a coccidian-specific PKA ortholog. This work delineates the signaling topology of AGC kinases that together control transitions within the asexual cycle of this important family of parasites.
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Affiliation(s)
- Alice L. Herneisen
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Michelle L. Peters
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Tyler A. Smith
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Emily Shortt
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
| | - Sebastian Lourido
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA
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7
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Deng B, Vanagas L, Alonso AM, Angel SO. Proteomics Applications in Toxoplasma gondii: Unveiling the Host-Parasite Interactions and Therapeutic Target Discovery. Pathogens 2023; 13:33. [PMID: 38251340 PMCID: PMC10821451 DOI: 10.3390/pathogens13010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/25/2023] [Accepted: 12/27/2023] [Indexed: 01/23/2024] Open
Abstract
Toxoplasma gondii, a protozoan parasite with the ability to infect various warm-blooded vertebrates, including humans, is the causative agent of toxoplasmosis. This infection poses significant risks, leading to severe complications in immunocompromised individuals and potentially affecting the fetus through congenital transmission. A comprehensive understanding of the intricate molecular interactions between T. gondii and its host is pivotal for the development of effective therapeutic strategies. This review emphasizes the crucial role of proteomics in T. gondii research, with a specific focus on host-parasite interactions, post-translational modifications (PTMs), PTM crosstalk, and ongoing efforts in drug discovery. Additionally, we provide an overview of recent advancements in proteomics techniques, encompassing interactome sample preparation methods such as BioID (BirA*-mediated proximity-dependent biotin identification), APEX (ascorbate peroxidase-mediated proximity labeling), and Y2H (yeast two hybrid), as well as various proteomics approaches, including single-cell analysis, DIA (data-independent acquisition), targeted, top-down, and plasma proteomics. Furthermore, we discuss bioinformatics and the integration of proteomics with other omics technologies, highlighting its potential in unraveling the intricate mechanisms of T. gondii pathogenesis and identifying novel therapeutic targets.
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Affiliation(s)
- Bin Deng
- Department of Biology and VBRN Proteomics Facility, University of Vermont, Burlington, VT 05405, USA
| | - Laura Vanagas
- Laboratorio de Parasitología Molecular, Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús 7130, Provincia de Buenos Aires, Argentina; (L.V.); (S.O.A.); (A.M.A.)
- Escuela de Bio y Nanotecnologías (UNSAM), 25 de Mayo y Francia. C.P., San Martín 1650, Provincia de Buenos Aires, Argentina
| | - Andres M. Alonso
- Laboratorio de Parasitología Molecular, Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús 7130, Provincia de Buenos Aires, Argentina; (L.V.); (S.O.A.); (A.M.A.)
- Escuela de Bio y Nanotecnologías (UNSAM), 25 de Mayo y Francia. C.P., San Martín 1650, Provincia de Buenos Aires, Argentina
| | - Sergio O. Angel
- Laboratorio de Parasitología Molecular, Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús 7130, Provincia de Buenos Aires, Argentina; (L.V.); (S.O.A.); (A.M.A.)
- Escuela de Bio y Nanotecnologías (UNSAM), 25 de Mayo y Francia. C.P., San Martín 1650, Provincia de Buenos Aires, Argentina
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8
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Yang C, Doud EH, Sampson E, Arrizabalaga G. The protein phosphatase PPKL is a key regulator of daughter parasite development in Toxoplasma gondii. mBio 2023; 14:e0225423. [PMID: 37877735 PMCID: PMC10746186 DOI: 10.1128/mbio.02254-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 09/14/2023] [Indexed: 10/26/2023] Open
Abstract
IMPORTANCE Toxoplasma gondii can cause severe disease in immunocompromised or immunosuppressed patients and during congenital infections. Treating toxoplasmosis presents enormous challenges since the parasite shares many biological processes with its mammalian hosts, which results in significant side effects with current therapies. Consequently, proteins that are essential and unique to the parasite represent favorable targets for drug development. Interestingly, Toxoplasma, like other members of the phylum Apicomplexa, has numerous plant-like proteins, many of which play crucial roles and do not have equivalents in the mammalian host. In this study, we found that the plant-like protein phosphatase PPKL appears to be a key regulator of daughter parasite development. With the depletion of PPKL, the parasite shows severe defects in forming daughter parasites. This study provides novel insights into the understanding of parasite division and offers a new potential target for the development of antiparasitic drugs.
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Affiliation(s)
- Chunlin Yang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Emma H. Doud
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Emily Sampson
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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9
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Liang QL, Nie LB, Elsheikha HM, Li TT, Sun LX, Zhang ZW, Wang M, Fu BQ, Zhu XQ, Wang JL. The Toxoplasma protein phosphatase 6 catalytic subunit (TgPP6C) is essential for cell cycle progression and virulence. PLoS Pathog 2023; 19:e1011831. [PMID: 38091362 PMCID: PMC10752510 DOI: 10.1371/journal.ppat.1011831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 12/27/2023] [Accepted: 11/16/2023] [Indexed: 12/28/2023] Open
Abstract
Protein phosphatases are post-translational regulators of Toxoplasma gondii proliferation, tachyzoite-bradyzoite differentiation and pathogenesis. Here, we identify the putative protein phosphatase 6 (TgPP6) subunits of T. gondii and elucidate their role in the parasite lytic cycle. The putative catalytic subunit TgPP6C and regulatory subunit TgPP6R likely form a complex whereas the predicted structural subunit TgPP6S, with low homology to the human PP6 structural subunit, does not coassemble with TgPP6C and TgPP6R. Functional studies showed that TgPP6C and TgPP6R are essential for parasite growth and replication. The ablation of TgPP6C significantly reduced the synchronous division of the parasite's daughter cells during endodyogeny, resulting in disordered rosettes. Moreover, the six conserved motifs of TgPP6C were required for efficient endodyogeny. Phosphoproteomic analysis revealed that ablation of TgPP6C predominately altered the phosphorylation status of proteins involved in the regulation of the parasite cell cycle. Deletion of TgPP6C significantly attenuated the parasite virulence in mice. Immunization of mice with TgPP6C-deficient type I RH strain induced protective immunity against challenge with a lethal dose of RH or PYS tachyzoites and Pru cysts. Taken together, the results show that TgPP6C contributes to the cell division, replication and pathogenicity in T. gondii.
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Affiliation(s)
- Qin-Li Liang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Lan-Bi Nie
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Hany M. Elsheikha
- Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, University of Nottingham, Loughborough, United Kingdom
| | - Ting-Ting Li
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China
| | - Li-Xiu Sun
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Zhi-Wei Zhang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Meng Wang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China
| | - Bao-Quan Fu
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China
| | - Xing-Quan Zhu
- Laboratory of Parasitic Diseases, College of Veterinary Medicine, Shanxi Agricultural University, Taigu, China
| | - Jin-Lei Wang
- State Key Laboratory for Animal Disease Control and Prevention, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China
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10
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Pasquarelli RR, Back PS, Sha J, Wohlschlegel JA, Bradley PJ. Identification of IMC43, a novel IMC protein that collaborates with IMC32 to form an essential daughter bud assembly complex in Toxoplasma gondii. PLoS Pathog 2023; 19:e1011707. [PMID: 37782662 PMCID: PMC10569561 DOI: 10.1371/journal.ppat.1011707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/12/2023] [Accepted: 09/23/2023] [Indexed: 10/04/2023] Open
Abstract
The inner membrane complex (IMC) of Toxoplasma gondii is essential for all phases of the parasite's life cycle. One of its most critical roles is to act as a scaffold for the assembly of daughter buds during replication by endodyogeny. While many daughter IMC proteins have been identified, most are recruited after bud initiation and are not essential for parasite fitness. Here, we report the identification of IMC43, a novel daughter IMC protein that is recruited at the earliest stages of daughter bud initiation. Using an auxin-inducible degron system we show that depletion of IMC43 results in aberrant morphology, dysregulation of endodyogeny, and an extreme defect in replication. Deletion analyses reveal a region of IMC43 that plays a role in localization and a C-terminal domain that is essential for the protein's function. TurboID proximity labelling and a yeast two-hybrid screen using IMC43 as bait identify 30 candidate IMC43 binding partners. We investigate two of these: the essential daughter protein IMC32 and a novel daughter IMC protein we named IMC44. We show that IMC43 is responsible for regulating the localization of both IMC32 and IMC44 at specific stages of endodyogeny and that this regulation is dependent on the essential C-terminal domain of IMC43. Using pairwise yeast two-hybrid assays, we determine that this region is also sufficient for binding to both IMC32 and IMC44. As IMC43 and IMC32 are both essential proteins, this work reveals the existence of a bud assembly complex that forms the foundation of the daughter IMC during endodyogeny.
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Affiliation(s)
- Rebecca R. Pasquarelli
- Molecular Biology Institute, University of California, Los Angeles, California, United States of America
| | - Peter S. Back
- Molecular Biology Institute, University of California, Los Angeles, California, United States of America
| | - Jihui Sha
- Department of Biological Chemistry and Institute of Genomics and Proteomics, University of California, Los Angeles, California, United States of America
| | - James A. Wohlschlegel
- Department of Biological Chemistry and Institute of Genomics and Proteomics, University of California, Los Angeles, California, United States of America
| | - Peter J. Bradley
- Molecular Biology Institute, University of California, Los Angeles, California, United States of America
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California, United States of America
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11
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Back PS, Senthilkumar V, Choi CP, Ly AM, Snyder AK, Lau JG, Ward GE, Bradley PJ. The Toxoplasma subpellicular network is highly interconnected and defines parasite shape for efficient motility and replication. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552545. [PMID: 37609316 PMCID: PMC10441382 DOI: 10.1101/2023.08.10.552545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Apicomplexan parasites possess several specialized structures to invade their host cells and replicate successfully. One of these is the inner membrane complex (IMC), a peripheral membrane-cytoskeletal system underneath the plasma membrane. It is composed of a series of flattened, membrane-bound vesicles and a cytoskeletal subpellicular network (SPN) comprised of intermediate filament-like proteins called alveolins. While the alveolin proteins are conserved throughout the Apicomplexa and the broader Alveolata, their precise functions and interactions remain poorly understood. Here, we describe the function of one of these alveolin proteins, TgIMC6. Disruption of IMC6 resulted in striking morphological defects that led to aberrant motility, invasion, and replication. Deletion analyses revealed that the alveolin domain alone is largely sufficient to restore localization and partially sufficient for function. As this highlights the importance of the IMC6 alveolin domain, we implemented unnatural amino acid photoreactive crosslinking to the alveolin domain and identified multiple binding interfaces between IMC6 and two other cytoskeletal proteins - IMC3 and ILP1. To our knowledge, this provides the first direct evidence of protein-protein interactions in the alveolin domain and supports the long-held hypothesis that the alveolin domain is responsible for filament formation. Collectively, our study features the conserved alveolin proteins as critical components that maintain the parasite's structural integrity and highlights the alveolin domain as a key mediator of SPN architecture.
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12
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Yang C, Doud EH, Sampson E, Arrizabalaga G. The protein phosphatase PPKL is a key regulator of daughter parasite development in Toxoplasma gondii. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544803. [PMID: 37398039 PMCID: PMC10312731 DOI: 10.1101/2023.06.13.544803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Apicomplexan parasites, including Toxoplasma gondii, encode many plant-like proteins, which play significant roles and present attractive targets for drug development. In this study, we have characterized the plant-like protein phosphatase PPKL, which is unique to the parasite and absent in its mammalian host. We have shown that its localization changes as the parasite divides. In non-dividing parasites, it is present in the cytoplasm, nucleus, and preconoidal region. As the parasite begins division, PPKL is enriched in the preconoidal region and the cortical cytoskeleton of the nascent parasites. Later in the division, PPKL is present in the basal complex ring. Conditional knockdown of PPKL showed that it is essential for parasite propagation. Moreover, parasites lacking PPKL exhibit uncoupling of division, with normal DNA duplication but severe defects in forming daughter parasites. While PPKL depletion does not impair the duplication of centrosomes, it affects the rigidity and arrangement of the cortical microtubules. Both Co-Immunoprecipitation and proximity labeling identified the kinase DYRK1 as a potential functional partner of PPKL. Complete knockout of DYRK1 phenocopies lack of PPKL, strongly suggesting a functional relationship between these two signaling proteins. Global phosphoproteomics analysis revealed a significant increase in phosphorylation of the microtubule-associated proteins SPM1 in PPKL-depleted parasites, suggesting PPKL regulates the cortical microtubules by mediating the phosphorylation state of SPM1. More importantly, the phosphorylation of cell cycle-associated kinase Crk1, a known regulator of daughter cell assembly, is altered in PPKL-depleted parasites. Thus, we propose that PPKL regulates daughter parasite development by influencing the Crk1-dependent signaling pathway.
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Affiliation(s)
- Chunlin Yang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Emma H. Doud
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Emily Sampson
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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