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Müller J, Hemphill A. Toxoplasma gondii infection: novel emerging therapeutic targets. Expert Opin Ther Targets 2023; 27:293-304. [PMID: 37212443 PMCID: PMC10330558 DOI: 10.1080/14728222.2023.2217353] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 04/24/2023] [Indexed: 05/23/2023]
Abstract
INTRODUCTION Toxoplasmosis constitutes a challenge for public health, animal production, and welfare. So far, only a limited panel of drugs has been marketed for clinical applications. In addition to classical screening, the investigation of unique targets of the parasite may lead to the identification of novel drugs. AREAS COVERED Herein, the authors describe the methodology to identify novel drug targets in Toxoplasma gondii and review the literature with a focus on the last two decades. EXPERT OPINION Over the last two decades, the investigation of essential proteins of T. gondii as potential drug targets has fostered the hope of identifying novel compounds for the treatment of toxoplasmosis. Despite good efficacies in vitro, only a few classes of these compounds are effective in suitable rodent models, and none has cleared the hurdle to applications in humans. This shows that target-based drug discovery is in no way better than classical screening approaches. In both cases, off-target effects and adverse side effects in the hosts must be considered. Proteomics-driven analyses of parasite- and host-derived proteins that physically bind drug candidates may constitute a suitable tool to characterize drug targets, irrespectively of the drug discovery methods.
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Affiliation(s)
- Joachim Müller
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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2
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Stasic AJ, Moreno SNJ, Carruthers VB, Dou Z. The Toxoplasma plant-like vacuolar compartment (PLVAC). J Eukaryot Microbiol 2022; 69:e12951. [PMID: 36218001 PMCID: PMC10576567 DOI: 10.1111/jeu.12951] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/28/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. T. gondii shares several characteristics with plants including a nonphotosynthetic plastid termed apicoplast and a multivesicular organelle that was named the plant-like vacuole (PLV) or vacuolar compartment (VAC). The name plant-like vacuole was selected based on its resemblance in composition and function to plant vacuoles. The name VAC represents its general vacuolar characteristics. We will refer to the organelle as PLVAC in this review. New findings in recent years have revealed that the PLVAC represents the lysosomal compartment of T. gondii which has adapted peculiarities to fulfill specific Toxoplasma needs. In this review, we discuss the composition and functions of the PLVAC highlighting its roles in ion storage and homeostasis, endocytosis, exocytosis, and autophagy.
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Affiliation(s)
- Andrew J Stasic
- Department of Microbiology, Heartland FPG, Carmel, Indiana, USA
| | - Silvia N J Moreno
- Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
| | - Vern B Carruthers
- Department of Microbiology & Immunology, University of Michigan Medical School, Michigan, Ann Arbor, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, South Carolina, Clemson, USA
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3
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Botwright NA, Mohamed AR, Slinger J, Lima PC, Wynne JW. Host-Parasite Interaction of Atlantic salmon ( Salmo salar) and the Ectoparasite Neoparamoeba perurans in Amoebic Gill Disease. Front Immunol 2021; 12:672700. [PMID: 34135900 PMCID: PMC8202022 DOI: 10.3389/fimmu.2021.672700] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/05/2021] [Indexed: 12/13/2022] Open
Abstract
Marine farmed Atlantic salmon (Salmo salar) are susceptible to recurrent amoebic gill disease (AGD) caused by the ectoparasite Neoparamoeba perurans over the growout production cycle. The parasite elicits a highly localized response within the gill epithelium resulting in multifocal mucoid patches at the site of parasite attachment. This host-parasite response drives a complex immune reaction, which remains poorly understood. To generate a model for host-parasite interaction during pathogenesis of AGD in Atlantic salmon the local (gill) and systemic transcriptomic response in the host, and the parasite during AGD pathogenesis was explored. A dual RNA-seq approach together with differential gene expression and system-wide statistical analyses of gene and transcription factor networks was employed. A multi-tissue transcriptomic data set was generated from the gill (including both lesioned and non-lesioned tissue), head kidney and spleen tissues naïve and AGD-affected Atlantic salmon sourced from an in vivo AGD challenge trial. Differential gene expression of the salmon host indicates local and systemic upregulation of defense and immune responses. Two transcription factors, znfOZF-like and znf70-like, and their associated gene networks significantly altered with disease state. The majority of genes in these networks are candidates for mediators of the immune response, cellular proliferation and invasion. These include Aurora kinase B-like, rho guanine nucleotide exchange factor 25-like and protein NDNF-like inhibited. Analysis of the N. perurans transcriptome during AGD pathology compared to in vitro cultured N. perurans trophozoites, as a proxy for wild type trophozoites, identified multiple gene candidates for virulence and indicates a potential master regulatory gene system analogous to the two-component PhoP/Q system. Candidate genes identified are associated with invasion of host tissue, evasion of host defense mechanisms and formation of the mucoid lesion. We generated a novel model for host-parasite interaction during AGD pathogenesis through integration of host and parasite functional profiles. Collectively, this dual transcriptomic study provides novel molecular insights into the pathology of AGD and provides alternative theories for future research in a step towards improved management of AGD.
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Affiliation(s)
- Natasha A Botwright
- Livestock and Aquaculture, CSIRO Agriculture and Food, St Lucia, QLD, Australia
| | - Amin R Mohamed
- Livestock and Aquaculture, CSIRO Agriculture and Food, St Lucia, QLD, Australia
| | - Joel Slinger
- Livestock and Aquaculture, CSIRO Agriculture and Food, Woorim, QLD, Australia
| | - Paula C Lima
- Livestock and Aquaculture, CSIRO Agriculture and Food, St Lucia, QLD, Australia
| | - James W Wynne
- Livestock and Aquaculture, CSIRO Agriculture and Food, Hobart, TAS, Australia
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Elkerdany ED, Elnassery SM, Arafa FM, Zaki SAF, Mady RF. In vitro effect of a novel protease inhibitor cocktail on Toxoplasma gondii tachyzoites. Exp Parasitol 2020; 219:108010. [PMID: 33007297 DOI: 10.1016/j.exppara.2020.108010] [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: 06/12/2020] [Revised: 08/31/2020] [Accepted: 09/28/2020] [Indexed: 11/30/2022]
Abstract
Toxoplasmosis is a zoonotic disease and a global food and water-borne infection. The disease is caused by the parasite Toxoplasma gondii, which is a highly successful and remarkable pathogen because of its ability to infect almost any nucleated cell in warm-blooded animals. The present study was done to demonstrate the effect of protease inhibitors cocktail (PIC), which inhibit both cysteine and serine proteases, on in vitro cultured T. gondii tachyzoites on HepG2 cell line. This was achieved by assessing its effect on the invasion of the host cells and the intracellular development of T.gondii tachyzoites through measuring their number and viability after their incubation with PIC. Based on the results of the study, it was evident that the inhibitory action of the PIC was effective when applied to tachyzoites before their cultivation on HepG2 cells. Pre-treatment of T.gondii tachyzoites with PIC resulted in failure of the invasion of most of the tachyzoites and decreased the intracellular multiplication and viability of the tachyzoites that succeeded in the initial invasion process. Ultrastructural studies showed morphological alteration in tachyzoites and disruption in their organelles. This effect was irreversible till the complete lysis of cell monolayer in cultures. It can be concluded that PIC, at in vitro levels, could prevent invasion and intracellular multiplication of Toxoplasma tachyzoites. In addition, it is cost effective compared to individual protease inhibitors. It also had the benefit of combined therapy as it lowered the concentration of each protease inhibitor used in the cocktail. Other in vivo experiments are required to validate the cocktail efficacy against toxoplasmosis. Further studies may be needed to establish the exact mechanism by which the PIC exerts its effect on Toxoplasma tachyzoites behavior and its secretory pathway.
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Affiliation(s)
- Eman D Elkerdany
- Department of Medical Parasitology, Faculty of Medicine, Alexandria University, Egypt.
| | - Suzanne M Elnassery
- Department of Medical Parasitology, Faculty of Medicine, Alexandria University, Egypt.
| | - Fadwa M Arafa
- Department of Medical Parasitology, Faculty of Medicine, Alexandria University, Egypt.
| | - Sahar Abdel-Fattah Zaki
- Department of Environmental Biotechnology, Genetic Engineering Biotechnology Institute, City of Scientific Research and Technological Applications, Egypt.
| | - Rasha F Mady
- Department of Medical Parasitology, Faculty of Medicine, Alexandria University, Egypt.
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5
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Zwicker JD, Smith D, Guerra AJ, Hitchens JR, Haug N, Vander Roest S, Lee P, Wen B, Sun D, Wang L, Keep RF, Xiang J, Carruthers VB, Larsen SD. Discovery and Optimization of Triazine Nitrile Inhibitors of Toxoplasma gondii Cathepsin L for the Potential Treatment of Chronic Toxoplasmosis in the CNS. ACS Chem Neurosci 2020; 11:2450-2463. [PMID: 32027110 DOI: 10.1021/acschemneuro.9b00674] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
With roughly 2 billion people infected, the neurotropic protozoan Toxoplasma gondii remains one of the most pervasive and infectious parasites. Toxoplasma infection is the second leading cause of death due to foodborne illness in the United States, causes severe disease in immunocompromised patients, and is correlated with several cognitive and neurological disorders. Currently, no therapies exist that are capable of eliminating the persistent infection in the central nervous system (CNS). In this study we report the identification of triazine nitrile inhibitors of Toxoplasma cathepsin L (TgCPL) from a high throughput screen and their subsequent optimization. Through rational design, we improved inhibitor potency to as low as 5 nM, identified pharmacophore features that can be exploited for isoform selectivity (up to 7-fold for TgCPL versus human isoform), and improved metabolic stability (t1/2 > 60 min in mouse liver microsomes) guided by a metabolite ID study. We demonstrated that this class of compounds is capable of crossing the blood-brain barrier in mice (1:1 brain/plasma at 2 h). Importantly, we also show for the first time that treatment of T. gondii bradyzoite cysts in vitro with triazine nitrile inhibitors reduces parasite viability with efficacy equivalent to a TgCPL genetic knockout.
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Affiliation(s)
- Jeffery D. Zwicker
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - David Smith
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Alfredo J. Guerra
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jacob R. Hitchens
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nicole Haug
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Steve Vander Roest
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Pil Lee
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bo Wen
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Duxin Sun
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lu Wang
- Pharmacokinetics Core, Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Richard F. Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jianming Xiang
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vern B. Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Scott D. Larsen
- Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Toxoplasma Cathepsin Protease B and Aspartyl Protease 1 Are Dispensable for Endolysosomal Protein Digestion. mSphere 2020; 5:5/1/e00869-19. [PMID: 32051238 PMCID: PMC7021471 DOI: 10.1128/msphere.00869-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Roughly one-third of the human population is chronically infected with the intracellular single-celled parasite Toxoplasma gondii, but little is known about how this organism persists inside people. Previous research suggested that a parasite proteolytic enzyme, termed cathepsin protease L, is important for Toxoplasma persistence; however, it remained possible that other associated proteolytic enzymes could also be involved in the long-term survival of the parasite during infection. Here, we show that two proteolytic enzymes associated with cathepsin protease L play dispensable roles and are dependent on cathepsin L to reach maturity, which differs from the corresponding enzymes in humans. These findings establish a divergent hierarchy of proteases and help focus attention principally on cathepsin protease L as a potential target for interrupting Toxoplasma chronic infection. The lysosome-like vacuolar compartment (VAC) is a major site of proteolysis in the intracellular parasite Toxoplasma gondii. Previous studies have shown that genetic ablation of a VAC-residing cysteine protease, cathepsin protease L (CPL), resulted in the accumulation of undigested protein in the VAC and loss of parasite viability during the chronic stage of infection. However, since the maturation of another VAC localizing protease, cathepsin protease B (CPB), is dependent on CPL, it remained unknown whether these defects result directly from ablation of CPL or indirectly from a lack of CPB maturation. Likewise, although a previously described cathepsin D-like aspartyl protease 1 (ASP1) could also play a role in proteolysis, its definitive residence and function in the Toxoplasma endolysosomal system were not well defined. Here, we demonstrate that CPB is not necessary for protein turnover in the VAC and that CPB-deficient parasites have normal growth and viability in both the acute and chronic stages of infection. We also show that ASP1 depends on CPL for correct maturation, and it resides in the T. gondii VAC, where, similar to CPB, it plays a dispensable role in protein digestion. Taken together with previous work, our findings suggest that CPL is the dominant protease in a hierarchy of proteolytic enzymes within the VAC. This unusual lack of redundancy for CPL in T. gondii makes it a single exploitable target for disrupting chronic toxoplasmosis. IMPORTANCE Roughly one-third of the human population is chronically infected with the intracellular single-celled parasite Toxoplasma gondii, but little is known about how this organism persists inside people. Previous research suggested that a parasite proteolytic enzyme, termed cathepsin protease L, is important for Toxoplasma persistence; however, it remained possible that other associated proteolytic enzymes could also be involved in the long-term survival of the parasite during infection. Here, we show that two proteolytic enzymes associated with cathepsin protease L play dispensable roles and are dependent on cathepsin L to reach maturity, which differs from the corresponding enzymes in humans. These findings establish a divergent hierarchy of proteases and help focus attention principally on cathepsin protease L as a potential target for interrupting Toxoplasma chronic infection.
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7
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Thornton LB, Teehan P, Floyd K, Cochrane C, Bergmann A, Riegel B, Stasic AJ, Di Cristina M, Moreno SNJ, Roepe PD, Dou Z. An ortholog of Plasmodium falciparum chloroquine resistance transporter (PfCRT) plays a key role in maintaining the integrity of the endolysosomal system in Toxoplasma gondii to facilitate host invasion. PLoS Pathog 2019; 15:e1007775. [PMID: 31170269 PMCID: PMC6553793 DOI: 10.1371/journal.ppat.1007775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/22/2019] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma gondii is an apicomplexan parasite with the ability to use foodborne, zoonotic, and congenital routes of transmission that causes severe disease in immunocompromised patients. The parasites harbor a lysosome-like organelle, termed the "Vacuolar Compartment/Plant-Like Vacuole" (VAC/PLV), which plays an important role in maintaining the lytic cycle and virulence of T. gondii. The VAC supplies proteolytic enzymes that contribute to the maturation of invasion effectors and that digest autophagosomes and endocytosed host proteins. Previous work identified a T. gondii ortholog of the Plasmodium falciparum chloroquine resistance transporter (PfCRT) that localized to the VAC. Here, we show that TgCRT is a membrane transporter that is functionally similar to PfCRT. We also genetically ablate TgCRT and reveal that the TgCRT protein plays a key role in maintaining the integrity of the parasite’s endolysosomal system by controlling morphology of the VAC. When TgCRT is absent, the VAC dramatically increases in volume by ~15-fold and overlaps with adjacent endosome-like compartments. Presumably to reduce aberrant swelling, transcription and translation of endolysosomal proteases are decreased in ΔTgCRT parasites. Expression of subtilisin protease 1 is significantly reduced, which impedes trimming of microneme proteins, and significantly decreases parasite invasion. Chemical or genetic inhibition of proteolysis within the VAC reverses these effects, reducing VAC size and partially restoring integrity of the endolysosomal system, microneme protein trimming, and invasion. Taken together, these findings reveal for the first time a physiological role of TgCRT in substrate transport that impacts VAC volume and the integrity of the endolysosomal system in T. gondii. Toxoplasma gondii is an obligate intracellular protozoan parasite that belongs to the phylum Apicomplexa and that infects virtually all warm-blooded organisms. Approximately one-third of the human population is infected with Toxoplasma. Toxoplasma invades host cells using processed invasion effectors. A lysosome-like organelle (VAC) is involved in refining these invasion effectors to reach their final forms. A T. gondii ortholog of the malarial chloroquine resistance transporter protein (TgCRT) was found to be localized to the VAC membrane. Although the mutated version of the malarial chloroquine resistance transporter (PfCRT) has been shown to confer resistance to chloroquine treatment, its physiologic function remains poorly understood. Comparison between the related PfCRT and TgCRT facilitates definition of the physiologic role of CRT proteins. Here, we report that TgCRT plays a key role in affecting the integrity and proteolytic activity of the VAC and adjacent organelles, the secretion of invasion effectors, and parasite invasion and virulence. To relieve osmotic stress caused by VAC swelling when TgCRT is deleted, parasites repress proteolysis within this organelle to decrease solute accumulation, which then has secondary effects on parasite invasion. Our findings highlight a common function for PfCRT and TgCRT in mediating small solute transport to affect apicomplexan parasite vacuolar size and function.
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Affiliation(s)
- L. Brock Thornton
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Paige Teehan
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Katherine Floyd
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Christian Cochrane
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Amy Bergmann
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Bryce Riegel
- Department of Chemistry, Georgetown University, NW, Washington DC, United States of America
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, NW, Washington DC, United States of America
| | - Andrew J. Stasic
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Manlio Di Cristina
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Paul D. Roepe
- Department of Chemistry, Georgetown University, NW, Washington DC, United States of America
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, NW, Washington DC, United States of America
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- * E-mail:
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Zhai Q, Fu Z, Hong Y, Yu X, Han Q, Lu K, Li H, Dou X, Zhu C, Liu J, Lin J, Li G. iTRAQ-Based Comparative Proteomic Analysis of Adult Schistosoma japonicum from Water Buffalo and Yellow Cattle. Front Microbiol 2018; 9:99. [PMID: 29467732 PMCID: PMC5808103 DOI: 10.3389/fmicb.2018.00099] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/16/2018] [Indexed: 01/08/2023] Open
Abstract
Schistosomiasis japonicum is one of the most severe zoonotic diseases in China. Water buffalo and yellow cattle are important reservoir hosts and the main transmission sources of Schistosoma japonicum in endemic areas. The susceptibility of these two hosts to schistosome infection is different, as water buffaloes are less susceptible to S. japonicum than yellow cattle. In this study, iTRAQ-coupled LC-MS/MS was applied to compare the protein expression profiles of adult schistosomes recovered from water buffalo with those of yellow cattle. A total of 131 differentially expressed proteins (DEPs) were identified, including 46 upregulated proteins and 85 downregulated proteins. The iTRAQ results were confirmed by Western blotting and quantitative real-time PCR. Further analysis indicated that these DEPs were primarily involved in protein synthesis, transcriptional regulation, protein proteolysis, cytoskeletal structure and oxidative stress response processes. The results revealed that some of the differential expression molecules may affect the development and survival of schistosomes in these two natural hosts. Of note, this study provides useful information for understanding the interplay between schistosomes and their final hosts.
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Affiliation(s)
- Qi Zhai
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Zhiqiang Fu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Yang Hong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Xingang Yu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Qian Han
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Ke Lu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Hao Li
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Xuefeng Dou
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Chuangang Zhu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Jinming Liu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Jiaojiao Lin
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Guoqing Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
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Han Y, Zhou A, Lu G, Zhao G, Sha W, Wang L, Guo J, Zhou J, Zhou H, Cong H, He S. DNA Vaccines Encoding Toxoplasma gondii Cathepsin C 1 Induce Protection against Toxoplasmosis in Mice. THE KOREAN JOURNAL OF PARASITOLOGY 2017; 55:505-512. [PMID: 29103265 PMCID: PMC5678475 DOI: 10.3347/kjp.2017.55.5.505] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 01/05/2023]
Abstract
Toxoplasma gondii cathepsin C proteases (TgCPC1, 2, and 3) are important for the growth and survival of T. gondii. In the present study, B-cell and T-cell epitopes of TgCPC1 were predicted using DNAstar and the Immune Epitope Database. A TgCPC1 DNA vaccine was constructed, and its ability to induce protective immune responses against toxoplasmosis in BALB/c mice was evaluated in the presence or absence of the adjuvant α-GalCer. As results, TgCPC1 DNA vaccine with or without adjuvant α-GalCer showed higher levels of IgG and IgG2a in the serum, as well as IL-2 and IFN-γ in the spleen compared to controls (PBS, pEGFP-C1, and α-Galcer). Upon challenge infection with tachyzoites of T. gondii (RH), pCPC1/α-Galcer immunized mice showed the longest survival among all the groups. Mice vaccinated with DNA vaccine without adjuvant (pCPC1) showed better protective immunity compared to other controls (PBS, pEGFP-C1, and α-Galcer). These results indicate that a DNA vaccine encoding TgCPC1 is a potential vaccine candidate against toxoplasmosis.
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Affiliation(s)
- Yali Han
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Aihua Zhou
- Department of Pediatrics, Provincial Hospital Affiliated to Shandong University, Shandong University School of Medicine, Jinan, Shandong, 250021, P. R. China
| | - Gang Lu
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Guanghui Zhao
- Qilu Hospital of Shandong University, Qingdao, Shandong, 266035, P. R. China
| | - Wenchao Sha
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Lin Wang
- Department of Jinan Children's Hospital, Jinan, Shandong, 250022, P. R. China
| | - Jingjing Guo
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Jian Zhou
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Huaiyu Zhou
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Hua Cong
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
| | - Shenyi He
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong, 250012, P. R. China
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Resistance towards monensin is proposed to be acquired in a Toxoplasma gondii model by reduced invasion and egress activities, in addition to increased intracellular replication. Parasitology 2017; 145:313-325. [PMID: 28870270 DOI: 10.1017/s0031182017001512] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Monensin (Mon) is an anticoccidial polyether ionophore widely used to control coccidiosis. The extensive use of polyether ionophores on poultry farms resulted in widespread resistance, but the underlying resistance mechanisms are unknown in detail. For analysing the mode of action by which resistance against polyether ionophores is obtained, we induced in vitro Mon resistance in Toxoplasma gondii-RH strain (MonR-RH) and compared it with the sensitive parental strain (Sen-RH). The proteome assessment of MonR-RH and Sen-RH strains was obtained after isotopic labelling using stable isotope labelling by amino acid in cell culture. Relative proteomic quantification between resistant and sensitive strains was performed using liquid chromatography-mass spectrometry/mass spectrometry. Overall, 1024 proteins were quantified and 52 proteins of them were regulated. The bioinformatic analysis revealed regulation of cytoskeletal and transmembrane proteins being involved in transport mechanisms, metal ion-binding and invasion. During invasion, actin and microneme protein 8 (MIC8) are seem to be important for conoid extrusion and forming moving junction with host cells, respectively. Actin was significantly upregulated, while MIC8 was downregulated, which indicate an invasion reduction in the resistant strain. Resistance against Mon is not a simple process but it involves reduced invasion and egress activity of T. gondii tachyzoites while intracellular replication is enhanced.
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Zhao G, Song X, Kong X, Zhang N, Qu S, Zhu W, Yang Y, Wang Q. Immunization with Toxoplasma gondii aspartic protease 3 increases survival time of infected mice. Acta Trop 2017; 171:17-23. [PMID: 28238685 DOI: 10.1016/j.actatropica.2017.02.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/19/2017] [Accepted: 02/06/2017] [Indexed: 01/10/2023]
Abstract
Aspartic proteases in the Toxoplasma gondii, called TgASP1, 2, 3, and 5, play essential roles in the life cycle. In a previous study, we have demonstrated that TgASP1 is an antigen that prolongs survival time of infected mice. As an in-depth study, we have investigated the protective immunity of TgSAP3. A bioinformatic analysis was used to predict the linear B-cell epitopes and potential Th-cell epitopes on TgASP3, the results suggested that it has a large number of excellent epitopes. Mice were inoculated with a recombinant eukaryotic expression vector to evaluate the immune protection against an infection with the virulent RH strain of T. gondii. The enhanced immune response and increased survival time (up to 18days) were observed for vaccinated mice, showing that the TgASP3 antigen can provides partial protection.
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Affiliation(s)
- Guanghui Zhao
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Xiaojie Song
- Department of Respiratory, Qilu Hospital of Shandong University, Qingdao, Shandong Province 255036, China.
| | - Xiangnan Kong
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Ning Zhang
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Shaoling Qu
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Wei Zhu
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Yanyan Yang
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
| | - Qian Wang
- Clinical Laboratory Medicine Center, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012, China.
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Han Y, Zhou A, Lu G, Zhao G, Wang L, Guo J, Song P, Zhou J, Zhou H, Cong H, He S. Protection via a ROM4 DNA vaccine and peptide against Toxoplasma gondii in BALB/c mice. BMC Infect Dis 2017; 17:59. [PMID: 28077075 PMCID: PMC5225637 DOI: 10.1186/s12879-016-2104-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 12/10/2016] [Indexed: 01/13/2023] Open
Abstract
Background Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite with a broad host range including most warm-blooded animals, including humans. T. gondii surface antigen 1 (SAG1) is a well-characterized T. gondii antigen. T. gondii expresses five nonmitochondrial rhomboid intramembrane proteases, TgROM1-5. TgROM4 is uniformly distributed on the surface of T. gondii and involved in regulating MIC2, MIC3, MIC6, and AMA1 during T. gondii invasion of host cells. Bioinformatics have predicted ROM4 B-cell and T-cell epitopes. Immunization strategy is also a key factor in determining the effectiveness of the immune response and has gained increasing attention in T. gondii vaccine research. In this study, we used a DNA prime-peptide boost vaccination regimen to assess the protective efficacy of various vaccination strategies using TgROM4. Methods We identified a polypeptide (YALLGALIPYCVEYWKSIPR) using a bioinformatics approach, and immunized mice using a DNA-prime and polypeptide-boost regimen. BALB/c mice were randomly divided into six groups, including three experimental groups (peptide, pROM4 and pROM4/peptide) and three control groups (PBS, pEGFP-C1 and pSAG1). Mice were then immunized intramuscularly four times. After immunization, IgG and cytokine productions were determined using enzyme-linked immunosorbent assays. The survival time of mice was evaluated after challenge with tachyzoites of T. gondii RH strain. Additionally, the number of cysts in the brain was determined after intragastric challenge with cysts of T. gondii PRU strain. Results Mice vaccinated with different immunization regimens (peptide, pROM4 and pROM4/peptide) elicited specific humoral and cellular responses, with high levels of IgG, IgG2a, and interferon (IFN)-γ. Moreover, IgG, IgG2a and IFN-γ levels were highest in the pROM4/peptide group. Immunized mice, especially those in the pROM4/peptide group, had prolonged survival times after challenge with tachyzoites and reduced numbers of brain cysts after infection compared with negative controls. Conclusion A DNA prime-peptide boost regimen based on ROM4 elicited the highest level of humoral and cellular immune responses among immunization regimens, and may be a promising approach to increase the efficacy of DNA immunization.
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Affiliation(s)
- Yali Han
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Aihua Zhou
- Department of Pediatrics, Provincial Hospital Affiliated to Shandong University, Shandong University School of Medicine, 250021, Jinan, Shandong Province, People's Republic of China
| | - Gang Lu
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Guanghui Zhao
- Qilu Hospital of shandong University, Qingdao, 266035, Shandong Province, People's Republic of China
| | - Lin Wang
- Department of Ji Nan Children's Hospital, 250022, Jinan, Shandong Province, People's Republic of China
| | - Jingjing Guo
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Pengxia Song
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Jian Zhou
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Huaiyu Zhou
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Hua Cong
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China
| | - Shenyi He
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, 250012, People's Republic of China.
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Hasanuzzaman AFM, Robledo D, Gómez-Tato A, Alvarez-Dios JA, Harrison PW, Cao A, Fernández-Boo S, Villalba A, Pardo BG, Martínez P. De novo transcriptome assembly of Perkinsus olseni trophozoite stimulated in vitro with Manila clam (Ruditapes philippinarum) plasma. J Invertebr Pathol 2016; 135:22-33. [DOI: 10.1016/j.jip.2016.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/18/2016] [Accepted: 01/24/2016] [Indexed: 12/13/2022]
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Saidi S, Nabian S, Ebrahimzade E, Najafi A, Moghaddam MM, Sazmand A, Torkzadeh-Mahani M, Tabrizi SS. Identification and characterization of a cathepsin L-like cysteine protease from Rhipicephalus (Boophilus) annulatus. EXPERIMENTAL & APPLIED ACAROLOGY 2016; 68:251-265. [PMID: 26597589 DOI: 10.1007/s10493-015-9993-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/05/2015] [Indexed: 06/05/2023]
Abstract
The tick Rhipicephalus (Boophilus) annulatus is one of the most important ectoparasites of bovines and is responsible for the transmission of different pathogens such as Babesia and Anaplasma. Cysteine proteases are involved in several host-tick interactions including invasion of host tissues, immune evasion, pathogen transmission, embryogenesis and blood digestion. In this study, the gene encoding R. annulatus cathepsin L-like enzyme (RaCL1) was cloned into pTZ57R/T vector, sequenced and analyzed using bioinformatics approaches. The nucleotide length of RaCL1 was 999 bp. Bioinformatics analysis showed 332 amino acids with an approximate molecular weight of 36.3 kDa which contained a signal peptide sequence (18 amino acids), pro-region (97 amino acids) and mature enzyme (217 amino acids). Multiple sequence alignment of the RaCL1 revealed high similarity to cathepsin L-like cysteine proteases from other tick species such as Rhipicephalus (Boophilus) microplus and Amblyomma variegatum. Based on bioinformatics analyses, results of this work suggest that RaCL1 can be a suitable candidate for the development of vaccine against R. annulatus.
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Affiliation(s)
- Shahin Saidi
- Department of Parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
| | - Sedighe Nabian
- Department of Parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
- Iranian Research Center for Tick and Tick-borne Diseases, Tehran, Iran.
| | - Elahe Ebrahimzade
- Department of Parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
| | - Ali Najafi
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | | | - Alireza Sazmand
- Department of Agriculture, Payame Noor University, Tehran, Iran.
| | - Masoud Torkzadeh-Mahani
- Department of Biotechnology, Institute of Science, High Technology and Environmental Science, Graduate University of Advanced Technology, Kerman, Iran.
| | - Saeed Sattari Tabrizi
- Department of Parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
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Secretion of Polypeptide Crystals from Tetrahymena thermophila Secretory Organelles (Mucocysts) Depends on Processing by a Cysteine Cathepsin, Cth4p. EUKARYOTIC CELL 2015; 14:817-33. [PMID: 26092918 DOI: 10.1128/ec.00058-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/10/2015] [Indexed: 01/26/2023]
Abstract
In many organisms, sophisticated mechanisms facilitate release of peptides in response to extracellular stimuli. In the ciliate Tetrahymena thermophila, efficient peptide secretion depends on specialized vesicles called mucocysts that contain dense crystalline cores that expand rapidly during exocytosis. Core assembly depends of endoproteolytic cleavage of mucocyst proproteins by an aspartyl protease, cathepsin 3 (CTH3). Here, we show that a second enzyme identified by expression profiling, Cth4p, is also required for processing of proGrl proteins and for assembly of functional mucocysts. Cth4p is a cysteine cathepsin that localizes partially to endolysosomal structures and appears to act downstream of, and may be activated by, Cth3p. Disruption of CTH4 results in cells (Δcth4) that show aberrant trimming of Grl proproteins, as well as grossly aberrant mucocyst exocytosis. Surprisingly, Δcth4 cells succeed in assembling crystalline mucocyst cores. However, those cores do not undergo normal directional expansion during exocytosis, and they thus fail to efficiently extrude from the cells. We could phenocopy the Δcth4 defects by mutating conserved catalytic residues, indicating that the in vivo function of Cth4p is enzymatic. Our results indicate that as for canonical proteins packaged in animal secretory granules, the maturation of mucocyst proproteins involves sequential processing steps. The Δcth4 defects uncouple, in an unanticipated way, the assembly of mucocyst cores and their subsequent expansion and thereby reveal a previously unsuspected aspect of polypeptide secretion in ciliates.
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Soares AMS, Carvalho LP, Melo EJT, Costa HPS, Vasconcelos IM, Oliveira JTA. A protein extract and a cysteine protease inhibitor enriched fraction from Jatropha curcas seed cake have in vitro anti-Toxoplasma gondii activity. Exp Parasitol 2015; 153:111-7. [PMID: 25816973 DOI: 10.1016/j.exppara.2015.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 03/12/2015] [Accepted: 03/20/2015] [Indexed: 01/21/2023]
Abstract
Toxoplasma gondii is a parasite of great medical and veterinary importance that has worldwide distribution and causes toxoplasmosis. There are few treatments available for toxoplasmosis and the search for plant extracts and compounds with anti-Toxoplasma activity is of utmost importance for the discovery of new active drugs. The objective of this study was to investigate the action of a protein extract and a protease inhibitor enriched fraction from J. curcas seed cake on developing tachyzoites of T. gondii-infected Vero cells. The protein extract (JcCE) was obtained after solubilization of the J. curcas seed cake with 100 mM sodium borate buffer, pH 10, centrifugation and dialysis of the resulting supernatant with the extracting buffer. JcCE was used for the in vitro assays of anti-Toxoplasma activity at 0.01, 0.1, 0.5, 1.5, 3.0 and 5.0 mg/ml concentration for 24 h. The results showed that JcCE reduced the percentage of infection and the number of intracellular parasites, but had no effect on the morphology of Vero cells up to 3.0 mg/mL. The cysteine protease inhibitor enriched fraction, which was obtained after chromatography of JcCE on Sephadex G-75 and presented a unique protein band following SDS-PAGE, reduced both the number of T. gondii infected cells and intracellular parasites. These results suggest that both JcCE and the cysteine protease inhibitor enriched fraction interfere with the intracellular growth of T. gondii.
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Affiliation(s)
- A M S Soares
- Laboratory of Plant Biochemistry, Centre for Agrarian and Environmental Sciences, Federal University of Maranhão, BR 222, Km 74, Chapadinha, Maranhão CEP: 65500-000, Brazil
| | - L P Carvalho
- Laboratory of Cell and Tissue Biology, Cellular Toxicology Section, Centre for Bioscience and Biotechnology, North Fluminense State University of Darcy Ribeiro, Alberto Lamego Av. 2000, Campos dos Goytacazes, Rio de Janeiro CEP: 28013-602, Brazil
| | - E J T Melo
- Laboratory of Cell and Tissue Biology, Cellular Toxicology Section, Centre for Bioscience and Biotechnology, North Fluminense State University of Darcy Ribeiro, Alberto Lamego Av. 2000, Campos dos Goytacazes, Rio de Janeiro CEP: 28013-602, Brazil
| | - H P S Costa
- Laboratory of Plant Defense Proteins, Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza CE 60451-970, Brazil
| | - I M Vasconcelos
- Laboratory of Plant Defense Proteins, Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza CE 60451-970, Brazil
| | - J T A Oliveira
- Laboratory of Plant Defense Proteins, Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza CE 60451-970, Brazil.
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Identification and characterization of a cathepsin-L-like peptidase in Eimeria tenella. Parasitol Res 2014; 113:4335-48. [DOI: 10.1007/s00436-014-4107-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 08/26/2014] [Indexed: 11/26/2022]
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Abstract
The protozoan parasite Toxoplasma gondii resides within a nonfusogenic vacuole during intracellular replication. Although the limiting membrane of this vacuole provides a protective barrier to acidification and degradation by lysosomal hydrolases, it also physically segregates the parasite from the host cytosol. Accordingly, it has been suggested that T. gondii acquires material from the host via membrane channels or transporters. The ability of the parasite to internalize macromolecules via endocytosis during intracellular replication has not been tested. Here, we show that Toxoplasma ingests host cytosolic proteins and digests them using cathepsin L and other proteases within its endolysosomal system. Ingestion was reduced in mutant parasites lacking an intravacuolar network of tubular membranes, implicating this apparatus as a possible conduit for trafficking to the parasite. Genetic ablation of proteins involved in the pathway is associated with diminished parasite replication and virulence attenuation. We show that both virulent type I and avirulent type II strain parasites ingest and digest host-derived protein, indicating that the pathway is not restricted to highly virulent strains. The findings provide the first definitive evidence that T. gondii internalizes proteins from the host during intracellular residence and suggest that protein digestion within the endolysosomal system of the parasite contributes to toxoplasmosis. Toxoplasma gondii causes significant disease in individuals with weak immune systems. Treatment options for this infection have drawbacks, creating a need to understand how this parasite survives within the cells it infects as a prelude to interrupting its survival strategies. This study reveals that T. gondii internalizes proteins from the cytoplasm of the cells it infects and degrades such proteins within a digestive compartment within the parasite. Disruption of proteins involved in the pathway reduced parasite replication and lessened disease severity. The identification of a novel parasite ingestion pathway opens opportunities to interfere with this process and improve the outcome of infection.
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Kumar S, Briguglio JS, Turkewitz AP. An aspartyl cathepsin, CTH3, is essential for proprotein processing during secretory granule maturation in Tetrahymena thermophila. Mol Biol Cell 2014; 25:2444-60. [PMID: 24943840 PMCID: PMC4142616 DOI: 10.1091/mbc.e14-03-0833] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In animal cells, the assembly of dense cores in secretory granules is controlled by proteolytic processing of proproteins. The same phenomenon occurs in the ciliate Tetrahymena thermophila, but the proteases involved appear to be highly unrelated, suggesting that similar regulatory mechanisms have different molecular origins. In Tetrahymena thermophila, peptides secreted via dense-core granules, called mucocysts, are generated by proprotein processing. We used expression profiling to identify candidate processing enzymes, which localized as cyan fluorescent protein fusions to mucocysts. Of note, the aspartyl cathepsin Cth3p plays a key role in mucocyst-based secretion, since knockdown of this gene blocked proteolytic maturation of the entire set of mucocyst proproteins and dramatically reduced mucocyst accumulation. The activity of Cth3p was eliminated by mutation of two predicted active-site mutations, and overexpression of the wild-type gene, but not the catalytic-site mutant, partially rescued a Mendelian mutant defective in mucocyst proprotein processing. Our results provide the first direct evidence for the role of proprotein processing in this system. Of interest, both localization and the CTH3 disruption phenotype suggest that the enzyme provides non–mucocyst-related functions. Phylogenetic analysis of the T. thermophila cathepsins, combined with prior work on the role of sortilin receptors in mucocyst biogenesis, suggests that repurposing of lysosomal enzymes was an important step in the evolution of secretory granules in ciliates.
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Affiliation(s)
- Santosh Kumar
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Joseph S Briguglio
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
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Characterization of the chloroquine resistance transporter homologue in Toxoplasma gondii. EUKARYOTIC CELL 2014; 13:1360-70. [PMID: 24859994 DOI: 10.1128/ec.00027-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) protein confer resistance to the antimalarial drug chloroquine. PfCRT localizes to the parasite digestive vacuole, the site of chloroquine action, where it mediates resistance by transporting chloroquine out of the digestive vacuole. PfCRT belongs to a family of transporter proteins called the chloroquine resistance transporter family. CRT family proteins are found throughout the Apicomplexa, in some protists, and in plants. Despite the importance of PfCRT in drug resistance, little is known about the evolution or native function of CRT proteins. The apicomplexan parasite Toxoplasma gondii contains one CRT family protein. We demonstrate that T. gondii CRT (TgCRT) colocalizes with markers for the vacuolar (VAC) compartment in these parasites. The TgCRT-containing VAC is a highly dynamic organelle, changing its morphology and protein composition between intracellular and extracellular forms of the parasite. Regulated knockdown of TgCRT expression resulted in modest reduction in parasite fitness and swelling of the VAC, indicating that TgCRT contributes to parasite growth and VAC physiology. Together, our findings provide new information on the role of CRT family proteins in apicomplexan parasites.
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Cirelli KM, Gorfu G, Hassan MA, Printz M, Crown D, Leppla SH, Grigg ME, Saeij JPJ, Moayeri M. Inflammasome sensor NLRP1 controls rat macrophage susceptibility to Toxoplasma gondii. PLoS Pathog 2014; 10:e1003927. [PMID: 24626226 PMCID: PMC3953412 DOI: 10.1371/journal.ppat.1003927] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/21/2013] [Indexed: 12/22/2022] Open
Abstract
Toxoplasma gondii is an intracellular parasite that infects a wide range of warm-blooded species. Rats vary in their susceptibility to this parasite. The Toxo1 locus conferring Toxoplasma resistance in rats was previously mapped to a region of chromosome 10 containing Nlrp1. This gene encodes an inflammasome sensor controlling macrophage sensitivity to anthrax lethal toxin (LT) induced rapid cell death (pyroptosis). We show here that rat strain differences in Toxoplasma infected macrophage sensitivity to pyroptosis, IL-1β/IL-18 processing, and inhibition of parasite proliferation are perfectly correlated with NLRP1 sequence, while inversely correlated with sensitivity to anthrax LT-induced cell death. Using recombinant inbred rats, SNP analyses and whole transcriptome gene expression studies, we narrowed the candidate genes for control of Toxoplasma-mediated rat macrophage pyroptosis to four genes, one of which was Nlrp1. Knockdown of Nlrp1 in pyroptosis-sensitive macrophages resulted in higher parasite replication and protection from cell death. Reciprocally, overexpression of the NLRP1 variant from Toxoplasma-sensitive macrophages in pyroptosis-resistant cells led to sensitization of these resistant macrophages. Our findings reveal Toxoplasma as a novel activator of the NLRP1 inflammasome in rat macrophages. Inflammasomes are multiprotein complexes that are a major component of the innate immune system. They contain “sensor” proteins that are responsible for detecting various microbial and environmental danger signals and function by activating caspase-1, an enzyme that mediates cleavage and release of the pro-inflammatory cytokines, IL-1β and IL-18. Toxoplasma gondii is a highly successful protozoan parasite capable of infecting a wide range of host species that have variable levels of resistance. Rat strains have been previously shown to vary in their susceptibility to this parasite. We report here that rat macrophages from different inbred strains also vary in sensitivity to Toxoplasma induced lysis. We find that NLRP1, an inflammasome sensor whose only known agonist is anthrax LT, is also activated by Toxoplasma infection. In rats there is a perfect correlation between NLRP1 sequence and macrophage sensitivity to Toxoplasma-induced rapid cell death, inhibition of parasite proliferation, and IL-1β/IL-18 processing. Nlrp1 genes from sensitive rat macrophages can confer sensitivity to this rapid cell death when expressed in Toxoplasma resistant rat macrophages. Our findings suggest Toxoplasma is a new activator of the NLRP1 inflammasome.
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Affiliation(s)
- Kimberly M. Cirelli
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Gezahegn Gorfu
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Musa A. Hassan
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Morton Printz
- Department of Pharmacology, University of California-San Diego, La Jolla, California, United States of America
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Michael E. Grigg
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
- * E-mail: (MEG); (JPJS); (MM)
| | - Jeroen P. J. Saeij
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
- * E-mail: (MEG); (JPJS); (MM)
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
- * E-mail: (MEG); (JPJS); (MM)
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Abstract
Induction of immunity that limits Toxoplasma gondii infection in mice is critically dependent on the activation of the innate immune response. In this study, we investigated the role of cytoplasmic nucleotide-binding domain and leucine-rich repeat containing a pyrin domain (NLRP) inflammasome sensors during acute toxoplasmosis in mice. We show that in vitro Toxoplasma infection of murine bone marrow-derived macrophages activates the NLRP3 inflammasome, resulting in the rapid production and cleavage of interleukin-1β (IL-1β), with no measurable cleavage of IL-18 and no pyroptosis. Paradoxically, Toxoplasma-infected mice produced large quantities of IL-18 but had no measurable IL-1β in their serum. Infection of mice deficient in NLRP3, caspase-1/11, IL-1R, or the inflammasome adaptor protein ASC led to decreased levels of circulating IL-18, increased parasite replication, and death. Interestingly, mice deficient in NLRP1 also displayed increased parasite loads and acute mortality. Using mice deficient in IL-18 and IL-18R, we show that this cytokine plays an important role in limiting parasite replication to promote murine survival. Our findings reveal T. gondii as a novel activator of the NLRP1 and NLRP3 inflammasomes in vivo and establish a role for these sensors in host resistance to toxoplasmosis. Inflammasomes are multiprotein complexes that are a major component of the innate immune system. They contain “sensor” proteins that are responsible for detecting various microbial and environmental danger signals and function by activating caspase-1, an enzyme that mediates cleavage and release of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18. Toxoplasma gondii is a highly successful protozoan parasite capable of infecting a wide range of host species that have variable levels of resistance. We report here that T. gondii is a novel activator of the NLRP1 and NLRP3 inflammasomes in vivo and establish a role for these sensors in host resistance to toxoplasmosis. Using mice deficient in IL-18 and IL-18R, we show that the IL-18 cytokine plays a pivotal role by limiting parasite replication to promote murine survival.
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Evolutionary repurposing of endosomal systems for apical organelle biogenesis in Toxoplasma gondii. Int J Parasitol 2014; 44:133-8. [DOI: 10.1016/j.ijpara.2013.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 12/20/2022]
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Selective chromogenic and fluorogenic peptide substrates for the assay of cysteine peptidases in complex mixtures. Anal Biochem 2014; 449:179-87. [PMID: 24388866 DOI: 10.1016/j.ab.2013.12.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/20/2013] [Accepted: 12/23/2013] [Indexed: 12/31/2022]
Abstract
This study describes the design, synthesis, and use of selective peptide substrates for cysteine peptidases of the C1 papain family, important in many biological processes. The structure of the newly synthesized substrates is Glp-Xaa-Ala-Y (where Glp=pyroglutamyl; Xaa=Phe or Val; and Y=pNA [p-nitroanilide], AMC [4-amino-7-methylcoumaride], or AFC [4-amino-7-trifluoromethyl-coumaride]). Substrates were synthesized enzymatically to guarantee selectivity of the reaction and optical purity of the target compounds, simplifying the scheme of synthesis and isolation of products. The hydrolysis of the synthesized substrates was evaluated by C1 cysteine peptidases from different organisms and with different functions, including plant enzymes papain, bromelain, ficin, and mammalian lysosomal cathepsins B and L. The new substrates were selective for C1 cysteine peptidases and were not hydrolyzed by serine, aspartic, or metallo peptidases. We demonstrated an application of the selectivity of the synthesized substrates during the chromatographic separation of a multicomponent set of digestive peptidases from a beetle, Tenebrio molitor. Used in combination with the cysteine peptidase inhibitor E-64, these substrates were able to differentiate cysteine peptidases from peptidases of other classes in midgut extracts from T. molitor larvae and larvae of the genus Tribolium; thus, they are useful in the analysis of complex mixtures containing peptidases from different classes.
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Zhao G, Zhou A, Lu G, Meng M, Sun M, Bai Y, Han Y, Wang L, Zhou H, Cong H, Zhao Q, Zhu XQ, He S. Identification and characterization of Toxoplasma gondii aspartic protease 1 as a novel vaccine candidate against toxoplasmosis. Parasit Vectors 2013; 6:175. [PMID: 23768047 PMCID: PMC3691725 DOI: 10.1186/1756-3305-6-175] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/09/2013] [Indexed: 11/26/2022] Open
Abstract
Background Toxoplasma gondii is an obligate intracellular parasite that can pose a serious threat to human health by causing toxoplasmosis. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance. Aspartic proteases play essential roles in the T. gondii lifecycle. The parasite has four aspartic protease encoding genes, which are called toxomepsin 1, 2, 3 and 5 (TgASP1, 2, 3 and 5, respectively). Methods Bioinformatics approaches have enabled us to identify several promising linear-B cell epitopes and potential Th-cell epitopes on TgASP1, thus supporting its potential as a DNA vaccine against toxoplasmosis. We expressed TgASP1 in Escherichia coli and used the purified protein to immunize BALB/c mice. The antibodies obtained were used to determine where TgASP1 was localized in the parasite. We also made a TgASP1 DNA vaccine construct and evaluated it for the level of protection conferred to mice against infection with the virulent RH strain of T. gondii. Results TgASP1 appears to be a membrane protein located primarily at the tip of the T. gondii tachyzoite. Investigation of its potential as a DNA vaccine showed that it elicited strong humoral and cellular immune responses in mice, and that these responses were mediated by Th-1 cells. Mice immunized with the vaccine had greater levels of protection against mortality following challenge with T. gondii RH tachyzoites than did those immunized with PBS or the empty vector control. Conclusions TgASP1 is a novel candidate DNA vaccine that merits further investigation.
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Affiliation(s)
- Guanghui Zhao
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, People's Republic of China
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Zhao G, Zhou A, Lv G, Meng M, Sun M, Bai Y, Han Y, Wang L, Zhou H, Cong H, Zhao Q, Zhu XQ, He S. Toxoplasma gondii cathepsin proteases are undeveloped prominent vaccine antigens against toxoplasmosis. BMC Infect Dis 2013; 13:207. [PMID: 23651838 PMCID: PMC3659040 DOI: 10.1186/1471-2334-13-207] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/01/2013] [Indexed: 12/31/2022] Open
Abstract
Background Toxoplasma gondii, an obligate intracellular apicomplexan parasite, infects a wide range of warm-blooded animals including humans. T. gondii expresses five members of the C1 family of cysteine proteases, including cathepsin B-like (TgCPB) and cathepsin L-like (TgCPL) proteins. TgCPB is involved in ROP protein maturation and parasite invasion, whereas TgCPL contributes to proteolytic maturation of proTgM2AP and proTgMIC3. TgCPL is also associated with the residual body in the parasitophorous vacuole after cell division has occurred. Both of these proteases are potential therapeutic targets in T. gondii. The aim of this study was to investigate TgCPB and TgCPL for their potential as DNA vaccines against T. gondii. Methods Using bioinformatics approaches, we analyzed TgCPB and TgCPL proteins and identified several linear-B cell epitopes and potential Th-cell epitopes in them. Based on these results, we assembled two single-gene constructs (TgCPB and TgCPL) and a multi-gene construct (pTgCPB/TgCPL) with which to immunize BALB/c mice and test their effectiveness as DNA vaccines. Results TgCPB and TgCPL vaccines elicited strong humoral and cellular immune responses in mice, both of which were Th-1 cell mediated. In addition, all of the vaccines protected the mice against infection with virulent T. gondii RH tachyzoites, with the multi-gene vaccine (pTgCPB/TgCPL) providing the highest level of protection. Conclusions T. gondii CPB and CPL proteases are strong candidates for development as novel DNA vaccines.
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Affiliation(s)
- Guanghui Zhao
- Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province 250012, P R China.
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Herman EK, Greninger AL, Visvesvara GS, Marciano-Cabral F, Dacks JB, Chiu CY. The mitochondrial genome and a 60-kb nuclear DNA segment from Naegleria fowleri, the causative agent of primary amoebic meningoencephalitis. J Eukaryot Microbiol 2013; 60:179-91. [PMID: 23360210 PMCID: PMC3594069 DOI: 10.1111/jeu.12022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 12/17/2012] [Accepted: 12/17/2012] [Indexed: 11/29/2022]
Abstract
Naegleria fowleri is a unicellular eukaryote causing primary amoebic meningoencephalitis, a neuropathic disease killing 99% of those infected, usually within 7-14 days. Naegleria fowleri is found globally in regions including the US and Australia. The genome of the related nonpathogenic species Naegleria gruberi has been sequenced, but the genetic basis for N. fowleri pathogenicity is unclear. To generate such insight, we sequenced and assembled the mitochondrial genome and a 60-kb segment of nuclear genome from N. fowleri. The mitochondrial genome is highly similar to its counterpart in N. gruberi in gene complement and organization, while distinct lack of synteny is observed for the nuclear segments. Even in this short (60-kb) segment, we identified examples of potential factors for pathogenesis, including ten novel N. fowleri-specific genes. We also identified a homolog of cathepsin B; proteases proposed to be involved in the pathogenesis of diverse eukaryotic pathogens, including N. fowleri. Finally, we demonstrate a likely case of horizontal gene transfer between N. fowleri and two unrelated amoebae, one of which causes granulomatous amoebic encephalitis. This initial look into the N. fowleri nuclear genome has revealed several examples of potential pathogenesis factors, improving our understanding of a neglected pathogen of increasing global importance.
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Affiliation(s)
- Emily K Herman
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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Dou Z, Coppens I, Carruthers VB. Non-canonical maturation of two papain-family proteases in Toxoplasma gondii. J Biol Chem 2012; 288:3523-34. [PMID: 23250753 DOI: 10.1074/jbc.m112.443697] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Proteases regulate key events during infection by the pervasive intracellular parasite Toxoplasma gondii. Understanding how parasite proteases mature from an inactive zymogen to an active enzyme is expected to inform new strategies for blocking their actions. Herein, we show that T. gondii cathepsin B protease (TgCPB) does not undergo self-maturation but instead requires the expression of a second papain-family cathepsin protease, TgCPL. Using recombinant enzymes we also show that TgCPL is capable of partially maturing TgCPB in vitro. Consistent with this interrelationship, antibodies with validated specificity detected TgCPB in the lysosome-like vacuolar compartment along with TgCPL. Our findings also establish that TgCPB does not localize to the rhoptries as previously reported. Accordingly, rhoptry morphology and rhoptry protein maturation are normal in TgCPB knock-out parasites. Finally, we show that although maturation of TgCPL is independent of TgCPB, it may involve an additional protease(s) in conjunction with self-maturation.
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Affiliation(s)
- Zhicheng Dou
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Cryptostatin, a chagasin-family cysteine protease inhibitor of Cryptosporidium parvum. Parasitology 2012; 139:1029-37. [PMID: 22444160 DOI: 10.1017/s0031182012000297] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cysteine proteases of pathogenic protozoan parasites play pivotal roles in the life cycle of parasites, but strict regulation of their activities is also essential for maintenance of parasite physiology and interaction with hosts. In this study, we identified and characterized cryptostatin, a novel inhibitor of cysteine protease (ICP) of Cryptosporidium parvum. Cryptostatin showed low sequence identity to other chagasin-family ICPs, but 3 motifs (NPTTG, GXGG, and RPW/F motifs), which are evolutionarily conserved in chagasin-family ICPs, were found in the sequence. The overall structure of cryptostatin consisted of 8 β-strands that progressed in parallel and closely resembled the immunoglobulin fold. Recombinant cryptostatin inhibited various cysteine proteases, including papain, human cathepsin B, human cathepsin L, and cryptopain-1, with K i's in the picomolar range. Cryptostatin was active over a wide pH range and was highly stable under physiological conditions. The protein was thermostable and retained its inhibitory activity even after incubation at 95°C. Cryptostatin formed tight complexes with cysteine proteases, so the complexes remained intact in the presence of sodium dodecyl sulfate and β-mercaptoethanol, but they were disassembled by boiling. An immunogold electron microscopy analysis demonstrated diffused localization of cryptostatin within oocystes and meronts, but not within trophozoites, which suggests a possible role for cryptostatin in host cell invasion by C. parvum.
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Identification of lead compounds targeting the cathepsin B-like enzyme of Eimeria tenella. Antimicrob Agents Chemother 2011; 56:1190-201. [PMID: 22143531 DOI: 10.1128/aac.05528-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Cysteine peptidases have been implicated in the development and pathogenesis of Eimeria. We have identified a single-copy cathepsin B-like cysteine peptidase gene in the genome database of Eimeria tenella (EtCatB). Molecular modeling of the predicted protein suggested that it differs significantly from host enzymes and could be a good drug target. EtCatB was expressed and secreted as a soluble, active, glycosylated mature enzyme from Pichia pastoris. Biochemical characterization of the recombinant enzyme confirmed that it is cathepsin B-like. Screening of a focused library against the enzyme identified three inhibitors (a nitrile, a thiosemicarbazone, and an oxazolone) that can be used as leads for novel drug discovery against Eimeria. The oxazolone scaffold is a novel cysteine peptidase inhibitor; it may thus find widespread use.
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