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de Sousa MCF, Imhof D, Hänggeli KPA, Choi R, Hulverson MA, Arnold SLM, Van Voorhis WC, Fan E, Roberto SS, Ortega-Mora LM, Hemphill A. Efficacy of the bumped kinase inhibitor BKI-1708 against the cyst-forming apicomplexan parasites Toxoplasma gondii and Neospora caninum in vitro and in experimentally infected mice. Int J Parasitol Drugs Drug Resist 2024; 25:100553. [PMID: 38917582 DOI: 10.1016/j.ijpddr.2024.100553] [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: 05/05/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 06/27/2024]
Abstract
Toxoplasma gondii and Neospora caninum are major worldwide morbidity-causing pathogens. Bumped kinase inhibitors (BKIs) are a compound class that has been optimized to target the apicomplexan calcium-dependent protein kinase 1 (CDPK1) - and several members of this class have proven to be safe and highly active in vitro and in vivo. BKI-1708 is based on a 5-aminopyrazole-4-carboxamide scaffold, and exhibited in vitro IC50 values of 120 nM for T. gondii and 480 nM for N. caninum β-galactosidase expressing strains, and did not affect human foreskin fibroblast (HFF) viability at concentrations up to 25 μM. Electron microscopy established that exposure of tachyzoite-infected fibroblasts to 2.5 μM BKI-1708 in vitro induced the formation of multinucleated schizont-like complexes (MNCs), characterized by continued nuclear division and harboring newly formed intracellular zoites that lack the outer plasma membrane. These zoites were unable to finalize cytokinesis to form infective tachyzoites. BKI-1708 did not affect zebrafish (Danio rerio) embryo development during the first 96 h following egg hatching at concentrations up to 2 μM. Treatments of mice with BKI-1708 at 20 mg/kg/day during five consecutive days resulted in drug plasma levels ranging from 0.14 to 4.95 μM. In vivo efficacy of BKI-1708 was evaluated by oral application of 20 mg/kg/day from day 9-13 of pregnancy in mice experimentally infected with N. caninum (NcSpain-7) tachyzoites or T. gondii (TgShSp1) oocysts. This resulted in significantly decreased cerebral parasite loads and reduced vertical transmission in both models without drug-induced pregnancy interference.
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Affiliation(s)
- Maria Cristina Ferreira de Sousa
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland.
| | - Dennis Imhof
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland
| | - Kai Pascal Alexander Hänggeli
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Switzerland
| | - Ryan Choi
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Matthew A Hulverson
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Samuel L M Arnold
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA; Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Wesley C Van Voorhis
- Center for Emerging and Re-emerging Infectious Diseases (CERID), Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Sánchez-Sánchez Roberto
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid, Spain
| | - Luis M Ortega-Mora
- SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid, Spain
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Bern, Switzerland.
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2
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Broncel M, Dominicus C, Vigetti L, Nofal SD, Bartlett EJ, Touquet B, Hunt A, Wallbank BA, Federico S, Matthews S, Young JC, Tate EW, Tardieux I, Treeck M. Profiling of myristoylation in Toxoplasma gondii reveals an N-myristoylated protein important for host cell penetration. eLife 2020; 9:e57861. [PMID: 32618271 PMCID: PMC7373427 DOI: 10.7554/elife.57861] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/27/2020] [Indexed: 12/26/2022] Open
Abstract
N-myristoylation is a ubiquitous class of protein lipidation across eukaryotes and N-myristoyl transferase (NMT) has been proposed as an attractive drug target in several pathogens. Myristoylation often primes for subsequent palmitoylation and stable membrane attachment, however, growing evidence suggests additional regulatory roles for myristoylation on proteins. Here we describe the myristoylated proteome of Toxoplasma gondii using chemoproteomic methods and show that a small-molecule NMT inhibitor developed against related Plasmodium spp. is also functional in Toxoplasma. We identify myristoylation on a transmembrane protein, the microneme protein 7 (MIC7), which enters the secretory pathway in an unconventional fashion with the myristoylated N-terminus facing the lumen of the micronemes. MIC7 and its myristoylation play a crucial role in the initial steps of invasion, likely during the interaction with and penetration of the host cell. Myristoylation of secreted eukaryotic proteins represents a substantial expansion of the functional repertoire of this co-translational modification.
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Affiliation(s)
- Malgorzata Broncel
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Caia Dominicus
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Luis Vigetti
- Institute for Advanced Biosciences, Team Membrane Dynamics of Parasite-Host Cell Interactions, CNRS UMR5309, INSERM U1209, Université Grenoble AlpesGrenobleFrance
| | - Stephanie D Nofal
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Edward J Bartlett
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City CampusLondonUnited Kingdom
| | - Bastien Touquet
- Institute for Advanced Biosciences, Team Membrane Dynamics of Parasite-Host Cell Interactions, CNRS UMR5309, INSERM U1209, Université Grenoble AlpesGrenobleFrance
| | - Alex Hunt
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Bethan A Wallbank
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Stefania Federico
- The Peptide Chemistry STP, The Francis Crick InstituteLondonUnited Kingdom
| | - Stephen Matthews
- Department of Life Sciences, Imperial College London, South KensingtonLondonUnited Kingdom
| | - Joanna C Young
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Edward W Tate
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City CampusLondonUnited Kingdom
| | - Isabelle Tardieux
- Institute for Advanced Biosciences, Team Membrane Dynamics of Parasite-Host Cell Interactions, CNRS UMR5309, INSERM U1209, Université Grenoble AlpesGrenobleFrance
| | - Moritz Treeck
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick InstituteLondonUnited Kingdom
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Yakubu RR, Nieves E, Weiss LM. The Methods Employed in Mass Spectrometric Analysis of Posttranslational Modifications (PTMs) and Protein-Protein Interactions (PPIs). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:169-198. [PMID: 31347048 DOI: 10.1007/978-3-030-15950-4_10] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mass Spectrometry (MS) has revolutionized the way we study biomolecules, especially proteins, their interactions and posttranslational modifications (PTM). As such MS has established itself as the leading tool for the analysis of PTMs mainly because this approach is highly sensitive, amenable to high throughput and is capable of assigning PTMs to specific sites in the amino acid sequence of proteins and peptides. Along with the advances in MS methodology there have been improvements in biochemical, genetic and cell biological approaches to mapping the interactome which are discussed with consideration for both the practical and technical considerations of these techniques. The interactome of a species is generally understood to represent the sum of all potential protein-protein interactions. There are still a number of barriers to the elucidation of the human interactome or any other species as physical contact between protein pairs that occur by selective molecular docking in a particular spatiotemporal biological context are not easily captured and measured.PTMs massively increase the complexity of organismal proteomes and play a role in almost all aspects of cell biology, allowing for fine-tuning of protein structure, function and localization. There are an estimated 300 PTMS with a predicted 5% of the eukaryotic genome coding for enzymes involved in protein modification, however we have not yet been able to reliably map PTM proteomes due to limitations in sample preparation, analytical techniques, data analysis, and the substoichiometric and transient nature of some PTMs. Improvements in proteomic and mass spectrometry methods, as well as sample preparation, have been exploited in a large number of proteome-wide surveys of PTMs in many different organisms. Here we focus on previously published global PTM proteome studies in the Apicomplexan parasites T. gondii and P. falciparum which offer numerous insights into the abundance and function of each of the studied PTM in the Apicomplexa. Integration of these datasets provide a more complete picture of the relative importance of PTM and crosstalk between them and how together PTM globally change the cellular biology of the Apicomplexan protozoa. A multitude of techniques used to investigate PTMs, mostly techniques in MS-based proteomics, are discussed for their ability to uncover relevant biological function.
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Affiliation(s)
- Rama R Yakubu
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Edward Nieves
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Louis M Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA. .,Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
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Yakubu RR, Weiss LM, Silmon de Monerri NC. Post-translational modifications as key regulators of apicomplexan biology: insights from proteome-wide studies. Mol Microbiol 2017; 107:1-23. [PMID: 29052917 DOI: 10.1111/mmi.13867] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/12/2022]
Abstract
Parasites of the Apicomplexa phylum, such as Plasmodium spp. and Toxoplasma gondii, undergo complex life cycles involving multiple stages with distinct biology and morphologies. Post-translational modifications (PTMs), such as phosphorylation, acetylation and glycosylation, regulate numerous cellular processes, playing a role in every aspect of cell biology. PTMs can occur on proteins at any time in their lifespan and through alterations of target protein activity, localization, protein-protein interactions, among other functions, dramatically increase proteome diversity and complexity. In addition, PTMs can be induced or removed on changes in cellular environment and state. Thus, PTMs are likely to be key regulators of developmental transitions, biology and pathogenesis of apicomplexan parasites. In this review we examine the roles of PTMs in both parasite-specific and conserved eukaryotic processes, and the potential crosstalk between PTMs, that together regulate the intricate lives of these protozoa.
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Affiliation(s)
- Rama R Yakubu
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA.,Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA
| | - Louis M Weiss
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA.,Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA
| | - Natalie C Silmon de Monerri
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA.,Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10128, USA
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6
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Varughese EA, Kasper S, Anneken EM, Yadav JS. SHP-2 Mediates Cryptosporidium parvum Infectivity in Human Intestinal Epithelial Cells. PLoS One 2015; 10:e0142219. [PMID: 26556238 PMCID: PMC4640876 DOI: 10.1371/journal.pone.0142219] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 10/19/2015] [Indexed: 01/17/2023] Open
Abstract
The parasite, Cryptosporidium parvum, induces human gastroenteritis through infection of host epithelial cells in the small intestine. During the initial stage of infection, C. parvum is reported to engage host mechanisms at the host cell-parasite interface to form a parasitophorous vacuole. We determined that upon infection, the larger molecular weight proteins in human small intestinal epithelial host cells (FHs 74 Int) appeared to globally undergo tyrosine dephosphorylation. In parallel, expression of the cytoplasmic protein tyrosine phosphatase Src homology-2 domain-containing phosphatase 2 (SHP-2) increased in a time-dependent manner. SHP-2 co-localized with the C. parvum sporozoite and this interaction increased the rate of C. parvum infectivity through SH2-mediated SHP-2 activity. Furthermore, we show that one potential target that SHP-2 acts upon is the focal adhesion protein, paxillin, which undergoes moderate dephosphorylation following infection, with inhibition of SHP-2 rescuing paxillin phosphorylation. Importantly, treatment with an inhibitor to SHP-2 and with an inhibitor to paxillin and Src family kinases, effectively decreased the multiplicity of C. parvum infection in a dose-dependent manner. Thus, our study reveals an important role for SHP-2 in the pathogenesis of C. parvum. Furthermore, while host proteins can be recruited to participate in the development of the electron dense band at the host cell-parasite interface, our study implies for the first time that SHP-2 appears to be recruited by the C. parvum sporozoite to regulate infectivity. Taken together, these findings suggest that SHP-2 and its down-stream target paxillin could serve as targets for intervention.
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Affiliation(s)
- Eunice A. Varughese
- Division of Environmental Genetics and Molecular Toxicology, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- National Exposure Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio, United States of America
- * E-mail: (EAV); (JSY)
| | - Susan Kasper
- Division of Environmental Genetics and Molecular Toxicology, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Emily M. Anneken
- National Exposure Research Laboratory, United States Environmental Protection Agency, Cincinnati, Ohio, United States of America
| | - Jagjit S. Yadav
- Division of Environmental Genetics and Molecular Toxicology, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail: (EAV); (JSY)
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Characterization of the Neospora caninum NcROP40 and NcROP2Fam-1 rhoptry proteins during the tachyzoite lytic cycle. Parasitology 2015; 143:97-113. [DOI: 10.1017/s0031182015001511] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
SUMMARYVirulence factors from the ROP2-family have been extensively studied in Toxoplasma gondii, but in the closely related Neospora caninum only NcROP2Fam-1 has been partially characterized to date. NcROP40 is a member of this family and was found to be more abundantly expressed in virulent isolates. Both NcROP2Fam-1 and NcROP40 were evaluated as vaccine candidates and exerted a synergistic effect in terms of protection against vertical transmission in mouse models, which suggests that they may be relevant for parasite pathogenicity. NcROP40 is localized in the rhoptry bulbs of tachyzoites and bradyzoites, but in contrast to NcROP2Fam-1, the protein does not associate with the parasitophorous vacuole membrane due to the lack of arginine-rich amphipathic helix in its sequence. Similarly to NcROP2Fam-1, NcROP40 mRNA levels are highly increased during tachyzoite egress and invasion. However, NcROP40 up-regulation does not appear to be linked to the mechanisms triggering egress. In contrast to NcROP2Fam-1, phosphorylation of NcROP40 was not observed during egress. Besides, NcROP40 secretion into the host cell was not successfully detected by immunofluorescence techniques. These findings indicate that NcROP40 and NcROP2Fam-1 carry out different functions, and highlight the need to elucidate the role of NcROP40 within the lytic cycle and to explain its relative abundance in tachyzoites.
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In Vitro and In Vivo Effects of the Bumped Kinase Inhibitor 1294 in the Related Cyst-Forming Apicomplexans Toxoplasma gondii and Neospora caninum. Antimicrob Agents Chemother 2015; 59:6361-74. [PMID: 26248379 DOI: 10.1128/aac.01236-15] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 07/22/2015] [Indexed: 12/11/2022] Open
Abstract
We report on the in vitro effects of the bumped kinase inhibitor 1294 (BKI-1294) in cultures of virulent Neospora caninum isolates Nc-Liverpool (Nc-Liv) and Nc-Spain7 and in two strains of Toxoplasma gondii (RH and ME49), all grown in human foreskin fibroblasts. In these parasites, BKI-1294 acted with 50% inhibitory concentrations (IC50s) ranging from 20 nM (T. gondii RH) to 360 nM (N. caninum Nc-Liv), and exposure of intracellular stages to 1294 led to the nondisjunction of newly formed tachyzoites, resulting in the formation of multinucleated complexes similar to complexes previously observed in BKI-1294-treated N. caninum beta-galactosidase-expressing parasites. However, such complexes were not seen in a transgenic T. gondii strain that expressed CDPK1 harboring a mutation (G to M) in the gatekeeper residue. In T. gondii ME49 and N. caninum Nc-Liv, exposure of cultures to BKI-1294 resulted in the elevated expression of mRNA coding for the bradyzoite marker BAG1. Unlike in bradyzoites, SAG1 expression was not repressed. Immunofluorescence also showed that these multinucleated complexes expressed SAG1 and BAG1 and the monoclonal antibody CC2, which binds to a yet unidentified bradyzoite antigen, also exhibited increased labeling. In a pregnant mouse model, BKI-1294 efficiently inhibited vertical transmission in BALB/c mice experimentally infected with one of the two virulent isolates Nc-Liv or Nc-Spain7, demonstrating proof of concept that this compound protected offspring from vertical transmission and disease. The observed deregulated antigen expression effect may enhance the immune response during BKI-1294 therapy and will be the subject of future studies.
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9
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Lasonder E, Green JL, Grainger M, Langsley G, Holder AA. Extensive differential protein phosphorylation as intraerythrocytic Plasmodium falciparum schizonts develop into extracellular invasive merozoites. Proteomics 2015; 15:2716-29. [PMID: 25886026 DOI: 10.1002/pmic.201400508] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 02/18/2015] [Accepted: 04/13/2015] [Indexed: 12/31/2022]
Abstract
Pathology of the most lethal form of malaria is caused by Plasmodium falciparum asexual blood stages and initiated by merozoite invasion of erythrocytes. We present a phosphoproteome analysis of extracellular merozoites revealing 1765 unique phosphorylation sites including 785 sites not previously detected in schizonts. All MS data have been deposited in the ProteomeXchange with identifier PXD001684 (http://proteomecentral.proteomexchange.org/dataset/PXD001684). The observed differential phosphorylation between extra and intraerythrocytic life-cycle stages was confirmed using both phospho-site and phospho-motif specific antibodies and is consistent with the core motif [K/R]xx[pS/pT] being highly represented in merozoite phosphoproteins. Comparative bioinformatic analyses highlighted protein sets and pathways with established roles in invasion. Within the merozoite phosphoprotein interaction network a subnetwork of 119 proteins with potential roles in cellular movement and invasion was identified and suggested that it is coregulated by a further small subnetwork of protein kinase A (PKA), two calcium-dependent protein kinases (CDPKs), a phosphatidyl inositol kinase (PI3K), and a GCN2-like elF2-kinase with a predicted role in translational arrest and associated changes in the ubquitinome. To test this notion experimentally, we examined the overall ubiquitination level in intracellular schizonts versus extracellular merozoites and found it highly upregulated in merozoites. We propose that alterations in the phosphoproteome and ubiquitinome reflect a starvation-induced translational arrest as intracellular schizonts transform into extracellular merozoites.
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Affiliation(s)
- Edwin Lasonder
- School of Biomedical and Healthcare Sciences, Plymouth University, Drake Circus, Plymouth, Devon, UK
| | - Judith L Green
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK
| | - Munira Grainger
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK
| | - Gordon Langsley
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes - Sorbonne Paris Cité, France.,Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
| | - Anthony A Holder
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK
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Roiko MS, Svezhova N, Carruthers VB. Acidification Activates Toxoplasma gondii Motility and Egress by Enhancing Protein Secretion and Cytolytic Activity. PLoS Pathog 2014; 10:e1004488. [PMID: 25375818 PMCID: PMC4223073 DOI: 10.1371/journal.ppat.1004488] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 09/24/2014] [Indexed: 12/03/2022] Open
Abstract
Pathogenic microbes rely on environmental cues to initiate key events during infection such as differentiation, motility, egress and invasion of cells or tissues. Earlier investigations showed that an acidic environment activates motility of the protozoan parasite T. gondii. Conversely, potassium ions, which are abundant in the intracellular milieu that bathes immotile replicating parasites, suppress motility. Since motility is required for efficient parasite cell invasion and egress we sought to better understand its regulation by environmental cues. We found that low pH stimulates motility by triggering Ca2+-dependent secretion of apical micronemes, and that this cue is sufficient to overcome suppression by potassium ions and drive parasite motility, cell invasion and egress. We also discovered that acidification promotes membrane binding and cytolytic activity of perforin-like protein 1 (PLP1), a pore-forming protein required for efficient egress. Agents that neutralize pH reduce the efficiency of PLP1-dependent perforation of host membranes and compromise egress. Finally, although low pH stimulation of microneme secretion promotes cell invasion, it also causes PLP1-dependent damage to host cells, suggesting a mechanism by which neutral extracellular pH subdues PLP1 activity to allow cell invasion without overt damage to the target cell. These findings implicate acidification as a signal to activate microneme secretion and confine cytolytic activity to egress without compromising the viability of the next cell infected. Toxoplasma and related parasites including those that cause malaria are obligate intracellular pathogens that replicate within a specialized compartment termed the parasitophorous vacuole. To infect new host cells these parasites must first escape from the parasitophorous vacuole and other limiting membranes of the currently infected cell. Escape, or egress as it is often called, depends on the timely release of adhesive proteins and lysis factors from secretory organelles called micronemes. Although this secretory event is crucial for egress, the natural environmental cues that trigger microneme secretion remain poorly defined. Here we discover that acidification of the parasitophorous vacuole is sufficient to trigger microneme secretion and promote the activity of a lysis factor called PLP1. We also show that pH-neutralizing drugs inhibit egress and provide evidence of parasitophorous vacuole acidification approximately coinciding with parasite egress from infected host cells. The findings support a working model in which acidification activates microneme dependent motility and lytic activity to execute egress and destruction of infected cells. The results also provide insight into how PLP1 lytic activity is stimulated during egress in an acidic environment and subsequently suppressed by the neutral extracellular environment, thus permitting cell invasion with minimal damage to the next target cell.
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Affiliation(s)
- Marijo S. Roiko
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Nadezhda Svezhova
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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11
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Tang Q, Andenmatten N, Hortua Triana MA, Deng B, Meissner M, Moreno SNJ, Ballif BA, Ward GE. Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii. Mol Biol Cell 2014; 25:2579-91. [PMID: 24989796 PMCID: PMC4148248 DOI: 10.1091/mbc.e13-11-0648] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Myosin A, an unconventional class XIV myosin of the protozoan parasite Toxoplasma gondii, undergoes calcium-dependent phosphorylation, providing a mechanism by which the parasite can regulate motility-based processes such as escape from the infected host cell at the end of the parasite's lytic cycle. Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
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Affiliation(s)
- Qing Tang
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
| | - Nicole Andenmatten
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bin Deng
- Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT 05405 Department of Biology, University of Vermont, Burlington, VT 05405
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
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12
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Jacot D, Frénal K, Marq JB, Sharma P, Soldati-Favre D. Assessment of phosphorylation inToxoplasmaglideosome assembly and function. Cell Microbiol 2014; 16:1518-32. [DOI: 10.1111/cmi.12307] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 04/16/2014] [Indexed: 01/10/2023]
Affiliation(s)
- Damien Jacot
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Karine Frénal
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Pushkar Sharma
- Eukaryotic Gene Expression Laboratory; National Institute of Immunology; New Delhi 110067 India
| | - Dominique Soldati-Favre
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
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13
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Butler CL, Lucas O, Wuchty S, Xue B, Uversky VN, White M. Identifying novel cell cycle proteins in Apicomplexa parasites through co-expression decision analysis. PLoS One 2014; 9:e97625. [PMID: 24841368 PMCID: PMC4026381 DOI: 10.1371/journal.pone.0097625] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 04/22/2014] [Indexed: 11/26/2022] Open
Abstract
Hypothetical proteins comprise roughly half of the predicted gene complement of Toxoplasma gondii and Plasmodium falciparum and represent the largest class of uniquely functioning proteins in these parasites. Following the idea that functional relationships can be informed by the timing of gene expression, we devised a strategy to identify the core set of apicomplexan cell division cycling genes with important roles in parasite division, which includes many uncharacterized proteins. We assembled an expanded list of orthologs from the T. gondii and P. falciparum genome sequences (2781 putative orthologs), compared their mRNA profiles during synchronous replication, and sorted the resulting set of dual cell cycle regulated orthologs (744 total) into protein pairs conserved across many eukaryotic families versus those unique to the Apicomplexa. The analysis identified more than 100 ortholog gene pairs with unknown function in T. gondii and P. falciparum that displayed co-conserved mRNA abundance, dynamics of cyclical expression and similar peak timing that spanned the complete division cycle in each parasite. The unknown cyclical mRNAs encoded a diverse set of proteins with a wide range of mass and showed a remarkable conservation in the internal organization of ordered versus disordered structural domains. A representative sample of cyclical unknown genes (16 total) was epitope tagged in T. gondii tachyzoites yielding the discovery of new protein constituents of the parasite inner membrane complex, key mitotic structures and invasion organelles. These results demonstrate the utility of using gene expression timing and dynamic profile to identify proteins with unique roles in Apicomplexa biology.
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Affiliation(s)
- Carrie L. Butler
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Olivier Lucas
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Stefan Wuchty
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bin Xue
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Michael White
- Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
- Florida Center for Drug Discovery and Innovation, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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14
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Frénal K, Kemp LE, Soldati-Favre D. Emerging roles for protein S-palmitoylation in Toxoplasma biology. Int J Parasitol 2014; 44:121-31. [PMID: 24184909 DOI: 10.1016/j.ijpara.2013.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 09/25/2013] [Accepted: 09/28/2013] [Indexed: 10/26/2022]
Abstract
Post-translational modifications are refined, rapidly responsive and powerful ways to modulate protein function. Among post-translational modifications, acylation is now emerging as a widespread modification exploited by eukaryotes, bacteria and viruses to control biological processes. Protein palmitoylation involves the attachment of palmitic acid, also known as hexadecanoic acid, to cysteine residues of integral and peripheral membrane proteins and increases their affinity for membranes. Importantly, similar to phosphorylation, palmitoylation is reversible and is becoming recognised as instrumental for the regulation of protein function by modulating protein interactions, stability, folding, trafficking and signalling. Palmitoylation appears to play a central role in the biology of the Apicomplexa, regulating critical processes such as host cell invasion which is vital for parasite survival and dissemination. The recent identification of over 400 palmitoylated proteins in Plasmodium falciparum erythrocytic stages illustrates the broad spread and impact of this modification on parasite biology. The main enzymes responsible for protein palmitoylation are multi-membrane protein S-acyl transferases harbouring a catalytic Asp-His-His-Cys (DHHC) motif. A global functional analysis of the repertoire of protein S-acyl transferases in Toxoplasma gondii and Plasmodium berghei has recently been performed. The essential nature of some of these enzymes illustrates the key roles played by this post-translational modification in the corresponding substrates implicated in fundamental processes such as parasite motility and organelle biogenesis. Toward a better understanding of the depalmitoylation event, a protein with palmitoyl protein thioesterase activity has been identified in T. gondii. TgPPT1/TgASH1 is the main target of specific acyl protein thioesterase inhibitors but is dispensable for parasite survival, suggesting the implication of other genes in depalmitoylation. Palmitoylation/depalmitoylation cycles are now emerging as potential novel regulatory networks and T. gondii represents a superb model organism in which to explore their significance.
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Affiliation(s)
- Karine Frénal
- Department of Microbiology and Molecular Medicine, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.
| | - Louise E Kemp
- Department of Microbiology and Molecular Medicine, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland
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Sharma P, Chitnis CE. Key molecular events during host cell invasion by Apicomplexan pathogens. Curr Opin Microbiol 2013; 16:432-7. [PMID: 23895827 DOI: 10.1016/j.mib.2013.07.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
The ability of Apicomplexan parasites to invade host cells is key to their survival and pathogenesis. Plasmodium and Toxoplasma parasites share common mechanisms for invasion of host cells. Secretion of microneme and rhoptry proteins, tight junction formation and assembly of an acto-myosin motor are key steps for successful invasion by both parasites. Here, we review our understanding of the molecular basis for these steps.
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