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Zhang S, Wang F, Zhang D, Liu D, Ding W, Springer TA, Song G. Structural insights into MIC2 recognition by MIC2-associated protein in Toxoplasma gondii. Commun Biol 2023; 6:895. [PMID: 37652989 PMCID: PMC10471735 DOI: 10.1038/s42003-023-05277-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 08/23/2023] [Indexed: 09/02/2023] Open
Abstract
Microneme protein 2 (MIC2) and MIC2-associated protein (M2AP) play crucial roles in the gliding motility and host cell invasion of Toxoplasma gondii. Complex formation between MIC2 and M2AP is required for maturation and transport from the microneme to the parasite surface. Previous studies showed that M2AP associates with the 6th TSR domain of MIC2 (TSR6), but the detailed interaction remains unclear. In this study, we report crystal structures of M2AP alone and in complex with TSR6. TSR domains have an unusually thin, long structure with a layer of intercalated residues on one side. The non-layered side of TSR6 with hotspot residue His-620 at the center binds to M2AP. Remarkably, we show that TSR6 residue Y602 is dynamic; it equilibrates between being part of the layer (the layered state) and in a flipped-out state in the absence of M2AP. However, when bound to M2AP, Y602 shifts to the flipped-out state. Our findings provide insights into the association and stabilization of MIC2-M2AP complex, and may be used to develop new therapies to prevent infections caused by this parasite.
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Affiliation(s)
- Su Zhang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 200241, Shanghai, China
| | - Fangfang Wang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 200241, Shanghai, China
| | - Dujuan Zhang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 200241, Shanghai, China
| | - Dongsheng Liu
- iHuman Institute, ShanghaiTech University, 201210, Shanghai, China
| | - Wei Ding
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Departments of Biological Chemistry and Molecular Pharmacology and of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Gaojie Song
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 200241, Shanghai, China.
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Marugan-Hernandez V, Sanchez-Arsuaga G, Vaughan S, Burrell A, Tomley FM. Do All Coccidia Follow the Same Trafficking Rules? Life (Basel) 2021; 11:life11090909. [PMID: 34575057 PMCID: PMC8465013 DOI: 10.3390/life11090909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/24/2021] [Accepted: 08/27/2021] [Indexed: 01/06/2023] Open
Abstract
The Coccidia are a subclass of the Apicomplexa and include several genera of protozoan parasites that cause important diseases in humans and animals, with Toxoplasma gondii becoming the ‘model organism’ for research into the coccidian molecular and cellular processes. The amenability to the cultivation of T. gondii tachyzoites and the wide availability of molecular tools for this parasite have revealed many mechanisms related to their cellular trafficking and roles of parasite secretory organelles, which are critical in parasite-host interaction. Nevertheless, the extrapolation of the T. gondii mechanisms described in tachyzoites to other coccidian parasites should be done carefully. In this review, we considered published data from Eimeria parasites, a coccidian genus comprising thousands of species whose infections have important consequences in livestock and poultry. These studies suggest that the Coccidia possess both shared and diversified mechanisms of protein trafficking and secretion potentially linked to their lifecycles. Whereas trafficking and secretion appear to be well conversed prior to and during host-cell invasion, important differences emerge once endogenous development commences. Therefore, further studies to validate the mechanisms described in T. gondii tachyzoites should be performed across a broader range of coccidians (including T. gondii sporozoites). In addition, further genus-specific research regarding important disease-causing Coccidia is needed to unveil the individual molecular mechanisms of pathogenesis related to their specific lifecycles and hosts.
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Affiliation(s)
- Virginia Marugan-Hernandez
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
- Correspondence: ; Tel.: +44-(0)-17-0766-9445
| | - Gonzalo Sanchez-Arsuaga
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK;
| | - Alana Burrell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK;
| | - Fiona M. Tomley
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms AL9 7TA, UK; (G.S.-A.); (F.M.T.)
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3
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Gao Y, Suding Z, Wang L, Liu D, Su S, Xu J, Hu J, Tao J. Full-length transcriptome sequence analysis of Eimeria necatrix unsporulated oocysts and sporozoites identifies genes involved in cellular invasion. Vet Parasitol 2021; 296:109480. [PMID: 34120030 DOI: 10.1016/j.vetpar.2021.109480] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 05/29/2021] [Accepted: 05/30/2021] [Indexed: 12/23/2022]
Abstract
Eimeria necatrix is one of the most pathogenic chicken coccidia and causes avian coccidiosis, an enteric disease of major economic importance worldwide. Eimeria parasites have complex developmental life cycles, with an exogenous phase in the environment and an endogenous phase in the chicken intestine. Oocysts excreted by chickens rapidly undergo meiosis and cell division to form eight haploid sporozoites (SZ). SZ liberated from sporocysts in the chicken intestine migrate to their preferred site of development to initiate cellular invasion. To date, almost nothing is known about the proteins that mediate parasite invasion in E. necatrix. In order to discover genes with functions involved in cellular invasion, the transcriptome profiles of E. necatrix unsporulated oocysts (UO) and SZ were analyzed using a combination of third-generation single-molecule real-time sequencing (TGS) and second-generation sequencing (SGS) followed by qRT-PCR validation. Correction of TGS long reads by SGS short reads resulted in 34,932 (UO) and 23,040 (SZ) consensus isoforms. After subsequent assembly, a total of 4949 and 4254 genes were identified from UO and SZ libraries, respectively. A total of 8376 genes were identified as differentially expressed genes (DEGs) between SZ and UO. Compared to UO, 4057 genes were upregulated and 4319 genes were downregulated in SZ. Approximately 1399 and 1758 genes were defined as stage-specific genes in SZ and UO, respectively. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that 2978 upregulated SZ genes were clustered into 29 GO terms, and 857 upregulated SZ genes were associated with 26 KEGG pathways. We also predicted a further 50 upregulated SZ genes and 73 upregulated UO genes encoding microneme proteins, apical membrane antigens, rhoptry neck proteins, rhoptry proteins, dense granule proteins, heat shock proteins, calcium-dependent protein kinases, cyclin-dependent kinases, cGMP-dependent protein kinase, and glycosylphosphatidylinositol-anchored surface antigens. Our data reveal new features of the E. necatrix transcriptional landscape and provide resources for the development of novel vaccine candidates against E. necatrix infection.
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Affiliation(s)
- Yang Gao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Zeyang Suding
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Lele Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Dandan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Shijie Su
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Jinjun Xu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
| | - Junjie Hu
- Biology Department, Yunnan University, Kunming, 650500, China.
| | - Jianping Tao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, China.
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4
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Wang Y, Zhou X, Wang H, Sun L, Wang B, Jiang Y, Li H, Zhang X, Li H, Zhao X. The role of Eimeria tenella EtCab protein in the attachment and invasion of host cells. Vet Parasitol 2021; 292:109415. [PMID: 33780830 DOI: 10.1016/j.vetpar.2021.109415] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/13/2021] [Accepted: 03/14/2021] [Indexed: 01/12/2023]
Abstract
Calcium-binding proteins (CaBPs) containing the specific calcium-binding motif (EF-hand) play a crucial role in important physiological events such as secretion, storage and signal transduction of cells. Recently, CaBPs have been found to be associated with host cell invasions in some parasites. In this study, an Eimeria tenella membrane-associated calcium-binding protein (EtCab) was cloned and its expression at different developmental stages, adhesive functions and host cell invasion in vitro were investigated. The results of the sequence analysis showed that EtCab contains six EF-hand motifs and the HDEL ER-retention signal belonging to the CREC (45 kDa calcium-binding protein, reticulocalbin, ER calcium-binding protein of 55 kDa, and calumenin) family. An indirect immunofluorescence assay (IFA) using specific polyclonal antibodies under permeabilized and nonpermeabilized conditions labeled EtCab on the surface of sporozoites. Quantitative real-time PCR and western blotting indicated that EtCab was highly transcribed and expressed in sporozoites. The attachment assay using a yeast surface display model showed that the adherence rates of EtCab expressed on the surfaces of yeasts to host cells were 2.5-fold greater than the control. Invasion inhibition assays revealed that specific polyclonal antibodies against EtCab significantly reduced the invasion rate of sporozoites on host cells compared to the control group (P < 0.01). These results suggest that EtCab plays an important role in the attachment and invasion of E. tenella to host cells.
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Affiliation(s)
- Yakun Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Xue Zhou
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Hanzhu Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Lingyu Sun
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Bingxiang Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Yingying Jiang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Huihui Li
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Xiao Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China
| | - Hongmei Li
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China.
| | - Xiaomin Zhao
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China.
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5
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Khurana S, Coffey MJ, John A, Uboldi AD, Huynh MH, Stewart RJ, Carruthers VB, Tonkin CJ, Goddard-Borger ED, Scott NE. Protein O-fucosyltransferase 2-mediated O-glycosylation of the adhesin MIC2 is dispensable for Toxoplasma gondii tachyzoite infection. J Biol Chem 2018; 294:1541-1553. [PMID: 30514763 DOI: 10.1074/jbc.ra118.005357] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
Toxoplasma gondii is a ubiquitous, obligate intracellular eukaryotic parasite that causes congenital birth defects, disease in immunocompromised individuals, and blindness. Protein glycosylation plays an important role in the infectivity and evasion of immune responses of many eukaryotic parasites and is also of great relevance to vaccine design. Here we demonstrate that micronemal protein 2 (MIC2), a motility-associated adhesin of T. gondii, has highly glycosylated thrombospondin repeat (TSR) domains. Using affinity-purified MIC2 and MS/MS analysis along with enzymatic digestion assays, we observed that at least seven C-linked and three O-linked glycosylation sites exist within MIC2, with >95% occupancy at these O-glycosylation sites. We found that addition of O-glycans to MIC2 is mediated by a protein O-fucosyltransferase 2 homolog (TgPOFUT2) encoded by the TGGT1_273550 gene. Even though POFUT2 homologs are important for stabilizing motility-associated adhesins and for host infection in other apicomplexan parasites, loss of TgPOFUT2 in T. gondii had only a modest impact on MIC2 levels and the wider parasite proteome. Consistent with this, both plaque formation and tachyzoite invasion were broadly similar in the presence or absence of TgPOFUT2. These findings indicate that TgPOFUT2 O-glycosylates MIC2 and that this glycan, in contrast to previous findings in another study, is dispensable in T. gondii tachyzoites and for T. gondii infectivity.
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Affiliation(s)
- Sachin Khurana
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael J Coffey
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alan John
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alessandro D Uboldi
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - My-Hang Huynh
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Rebecca J Stewart
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Christopher J Tonkin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Ethan D Goddard-Borger
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia.
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Yan M, Cui X, Zhao Q, Zhu S, Huang B, Wang L, Zhao H, Liu G, Li Z, Han H, Dong H. Molecular characterization and protective efficacy of the microneme 2 protein from Eimeria tenella. ACTA ACUST UNITED AC 2018; 25:60. [PMID: 30474601 PMCID: PMC6254105 DOI: 10.1051/parasite/2018061] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/12/2018] [Indexed: 11/14/2022]
Abstract
Microneme proteins play an important role in the adherence of apicomplexan parasites to host cells during the invasion process. In this study, the microneme 2 protein from the protozoan parasite Eimeria tenella (EtMIC2) was cloned, characterized, and its protective efficacy as a DNA vaccine investigated. The EtMIC2 gene, which codes for a 35.07 kDa protein in E. tenella sporulated oocysts, was cloned and recombinant EtMIC2 protein (rEtMIC2) was produced in an Escherichia coli expression system. Immunostaining with an anti-rEtMIC2 antibody showed that the EtMIC2 protein mainly localized in the anterior region and membrane of sporozoites, in the cytoplasm of first- and second-generation merozoites, and was strongly expressed during first-stage schizogony. In addition, incubation with specific antibodies against EtMIC2 was found to efficiently reduce the ability of E. tenella sporozoites to invade host cells. Furthermore, animal-challenge experiments demonstrated that immunization with pcDNA3.1(+)-EtMIC2 significantly increased average body weight gain, while decreasing the mean lesion score and oocyst output in chickens. Taken together, these results suggest that EtMIC2 plays an important role in parasite cell invasion and may be a viable candidate for the development of new vaccines against E. tenella infection in chickens.
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Affiliation(s)
- Ming Yan
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Xiaoxia Cui
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - Qingdao Yebio Biological Engineering Co., Ltd, Qingdao 266114, PR China
| | - Qiping Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Shunhai Zhu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Bing Huang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Lu Wang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Huanzhi Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Guiling Liu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Zhihang Li
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China - College of Life and Environment Sciences, Shanghai Normal University, Shanghai 200234, PR China
| | - Hongyu Han
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
| | - Hui Dong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai 200241, PR China
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7
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Marugan-Hernandez V, Long E, Blake D, Crouch C, Tomley F. Eimeria tenella protein trafficking: differential regulation of secretion versus surface tethering during the life cycle. Sci Rep 2017; 7:4557. [PMID: 28676667 PMCID: PMC5496917 DOI: 10.1038/s41598-017-04049-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 05/08/2017] [Indexed: 01/15/2023] Open
Abstract
Eimeria spp. are intracellular parasites that have a major impact on poultry. Effective live vaccines are available and the development of reverse genetic technologies has raised the prospect of using Eimeria spp. as recombinant vectors to express additional immunoprotective antigens. To study the ability of Eimeria to secrete foreign antigens or display them on the surface of the sporozoite, transiently transfected populations of E. tenella expressing the fluorescent protein mCherry, linked to endogenous signal peptide (SP) and glycophosphatidylinositol-anchor (GPI) sequences, were examined. The SP from microneme protein EtMIC2 (SP2) allowed efficient trafficking of mCherry to cytoplasmic vesicles and following the C-terminal addition of a GPI-anchor (from surface antigen EtSAG1) mCherry was expressed on the sporozoite surface. In stable transgenic populations, mCherry fused to SP2 was secreted into the sporocyst cavity of the oocysts and after excystation, secretion was detected in culture supernatants but not into the parasitophorous vacuole after invasion. When the GPI was incorporated, mCherry was observed on the sporozites surface and in the supernatant of invading sporozoites. The proven secretion and surface exposure of mCherry suggests that antigen fusions with SP2 and GPI of EtSAG1 may be promising candidates to examine induction of protective immunity against heterologous pathogens.
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Affiliation(s)
- V Marugan-Hernandez
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK.
| | - E Long
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
| | - D Blake
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
| | - C Crouch
- MSD Animal Health, Walton Manor, Milton Keynes, MK7 7AJ, UK
| | - F Tomley
- The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, AL9 7TA, UK
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Zhang Z, Liu X, Yang X, Liu L, Wang S, Lu M, Ehsan M, Gadahi JA, Song X, Xu L, Yan R, Li X. The Molecular Characterization and Immunity Identification of Microneme 3 of Eimeria acervulina. J Eukaryot Microbiol 2016; 63:709-721. [PMID: 27037629 DOI: 10.1111/jeu.12318] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/29/2016] [Accepted: 03/30/2016] [Indexed: 11/30/2022]
Abstract
The gene of Eimeria acervulina microneme protein 3 (EaMIC3) was cloned and characterized. According to the conserved sequence, the 3'- and 5'-ends of EaMIC3 were amplified by the rapid amplification of cDNA ends (RACE). The full length cDNA of this gene was obtained by overlapping the sequences of 3'- and 5'-extremities and amplification by reverse transcription PCR. The sequence analysis revealed that the opening reading frame (ORF) of EaMIC3 was 2,607 bp and encoded a protein of 868 amino acids with 93.04 kDa. Western blotting assay showed that the recombinant protein was successfully recognized by the sera of chickens experimentally infected with E. acervulina, whereas the native protein in the somatic extract of sporozoites was as well detected by sera from rats immunized with the recombinant protein of EaMIC3. Immunofluorescence analysis indicated that EaMIC3 was expressed in the sporozoites and merozoites stages of E. acervulina. Animal challenge experiments demonstrated that the recombinant protein of EaMIC3 could significantly increase the average body weight gains, decrease the mean lesion scores and the oocyst outputs of the immunized chickens and presented anticoccidial index (ACI) more than 165. Moreover, EaMIC3 protein produced significantly high level of IgG antibody, IFN-γ, IL-10, IL-17 TGF-β, CD4+ , and CD8+ .
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Affiliation(s)
- ZhenChao Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - XinChao Liu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - XinChao Yang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - LianRui Liu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Shuai Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - MingMin Lu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Mohammad Ehsan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - Javaid A Gadahi
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - XiaoKai Song
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - LiXin Xu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - RuoFeng Yan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China
| | - XiangRui Li
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
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9
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Zhang Z, Liu L, Huang J, Wang S, Lu M, Song X, Xu L, Yan R, Li X. The molecular characterization and immune protection of microneme 2 of Eimeria acervulina. Vet Parasitol 2016; 215:96-105. [DOI: 10.1016/j.vetpar.2015.10.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/26/2015] [Accepted: 10/27/2015] [Indexed: 10/22/2022]
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10
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Huynh MH, Liu B, Henry M, Liew L, Matthews SJ, Carruthers VB. Structural basis of Toxoplasma gondii MIC2-associated protein interaction with MIC2. J Biol Chem 2014; 290:1432-41. [PMID: 25411252 DOI: 10.1074/jbc.m114.613646] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Toxoplasma gondii parasites must actively invade host cells to propagate. Secretory microneme proteins have been shown to be important for both gliding motility and active invasion. MIC2-M2AP is a protein complex that is essential for productive motility and rapid invasion by binding to host cell surface receptors. To investigate the architecture of the MIC2 and M2AP complex, we identified the minimal domains sufficient for interaction and solved the NMR solution structure of the globular domain of M2AP. We found that M2AP adopts a modified galectin fold similar to the C-terminal domain of another microneme protein, MIC1. NMR and immunoprecipitation analyses implicated hydrophobic residues on one face of the M2AP galectin fold in binding to the membrane proximal sixth thrombospondin type I repeat domain of MIC2. Our findings provide a second example of a galectin fold adapted for microneme protein-protein interactions and suggest a conserved strategy for the assembly and folding of diverse protein complexes.
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Affiliation(s)
- My-Hang Huynh
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
| | - Bing Liu
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Maud Henry
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Lloyd Liew
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Stephen J Matthews
- the Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Vern B Carruthers
- From the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
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11
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Liu Q, Chen Z, Shi W, Sun H, Zhang J, Li H, Xiao Y, Wang F, Zhao X. Preparation and initial application of monoclonal antibodies that recognize Eimeria tenella microneme proteins 1 and 2. Parasitol Res 2014; 113:4151-61. [DOI: 10.1007/s00436-014-4087-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 08/18/2014] [Indexed: 11/30/2022]
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12
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A conserved apicomplexan microneme protein contributes to Toxoplasma gondii invasion and virulence. Infect Immun 2014; 82:4358-68. [PMID: 25092910 DOI: 10.1128/iai.01877-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii critically relies on host cell invasion during infection. Proteins secreted from the apical micronemes are central components for host cell recognition, invasion, egress, and virulence. Although previous work established that the sporozoite protein with an altered thrombospondin repeat (SPATR) is a micronemal protein conserved in other apicomplexan parasites, including Plasmodium, Neospora, and Eimeria, no genetic evidence of its contribution to invasion has been reported. SPATR contains a predicted epidermal growth factor domain and two thrombospondin type 1 repeats, implying a role in host cell recognition. In this study, we assess the contribution of T. gondii SPATR (TgSPATR) to T. gondii invasion by genetically ablating it and restoring its expression by genetic complementation. Δspatr parasites were ~50% reduced in invasion compared to parental strains, a defect that was reversed in the complemented strain. In mouse virulence assays, Δspatr parasites were significantly attenuated, with ~20% of mice surviving infection. Given the conservation of this protein among the Apicomplexa, we assessed whether the Plasmodium falciparum SPATR ortholog (PfSPATR) could complement the absence of the TgSPATR. Although PfSPATR showed correct micronemal localization, it did not reverse the invasion deficiency of Δspatr parasites, because of an apparent failure in secretion. Overall, the results suggest that TgSPATR contributes to invasion and virulence, findings that have implications for the many genera and life stages of apicomplexans that express SPATR.
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13
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Monney T, Hemphill A. Vaccines against neosporosis: what can we learn from the past studies? Exp Parasitol 2014; 140:52-70. [PMID: 24602874 DOI: 10.1016/j.exppara.2014.02.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 02/09/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
Abstract
Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against N. caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.
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Affiliation(s)
- Thierry Monney
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland
| | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
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14
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Chapman HD, Barta JR, Blake D, Gruber A, Jenkins M, Smith NC, Suo X, Tomley FM. A selective review of advances in coccidiosis research. ADVANCES IN PARASITOLOGY 2014; 83:93-171. [PMID: 23876872 DOI: 10.1016/b978-0-12-407705-8.00002-1] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Coccidiosis is a widespread and economically significant disease of livestock caused by protozoan parasites of the genus Eimeria. This disease is worldwide in occurrence and costs the animal agricultural industry many millions of dollars to control. In recent years, the modern tools of molecular biology, biochemistry, cell biology and immunology have been used to expand greatly our knowledge of these parasites and the disease they cause. Such studies are essential if we are to develop new means for the control of coccidiosis. In this chapter, selective aspects of the biology of these organisms, with emphasis on recent research in poultry, are reviewed. Topics considered include taxonomy, systematics, genetics, genomics, transcriptomics, proteomics, transfection, oocyst biogenesis, host cell invasion, immunobiology, diagnostics and control.
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Affiliation(s)
- H David Chapman
- Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas, USA.
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15
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Partial protective of chickens against Eimeria tenella challenge with recombinant EtMIC-1 antigen. Parasitol Res 2013; 112:2281-7. [PMID: 23559377 DOI: 10.1007/s00436-013-3389-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 03/08/2013] [Indexed: 01/16/2023]
Abstract
Eimeria tenella microneme protein 1 (EtMIC-1) is highly conserved with TgMIC-2, which is involved in parasite binding specifically to host cells. Little is known about the immune responses and protective efficacy against E. tenella infection with EtMIC-1 antigen. In the present study, the recombinant proteins of E. tenella mature MIC-1 and adhesive domain (von Willebrand factor type A domain, EtMIC-1-VD) were obtained, protective efficacy against E.tenella infection and the mucosal immune response, which is induced in broilers was evaluated. The antibody levels and the transcription profiles of cytokine of chickens, such as interleukin-12 (IL-12) and interferon-γ (IFN-γ), were detected after being immunized three times with the recombinant EtMIC-1 and EtMIC-1-VD by ELISA assay and quantitative real-time PCR, respectively. The results showed that both groups of chickens, after being immunized with 100 μg EtMIC-1 or EtMIC-1-VD antigen, induced about tenfold higher IgG levels compared to the nonimmune groups. The transcription profiles of IL-12 and IFN-γ of the immunized groups were significantly higher than the control groups as well. The anticoccidial index of the group immunized with 100 μg EtMIC-1 and the group immunized with 100 μg EtMIC-1-VD were 167.2 and 165.5, respectively, which are significantly higher than low-dose immunized groups and challenged control groups. Our data suggests that VD domain is the key functional structure of EtMIC-1 that could trigger a significant humoral and cellular response against E. tenella infection, and EtMIC-1 had the potential in imparting partial protection in chickens against homologous challenge.
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16
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Limenitakis J, Soldati-Favre D. Functional genetics in Apicomplexa: potentials and limits. FEBS Lett 2011; 585:1579-88. [PMID: 21557944 DOI: 10.1016/j.febslet.2011.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 01/15/2023]
Abstract
The Apicomplexans are obligate intracellular protozoan parasites and the causative agents of severe diseases in humans and animals. Although complete genome sequences are available since many years and for several parasites, they are replete with putative genes of unassigned function. Forward and reverse genetic approaches are limited only to a few Apicomplexans that can either be propagated in vitro or in a convenient animal model. This review will compare and contrast the most recent strategies developed for the genetic manipulation of Plasmodium falciparum, Plasmodium berghei and Toxoplasma gondii that have taken advantage of the intrinsic features of their respective genomes. Efforts towards the improvement of the transfection efficiencies in malaria parasites, the development of approaches to study essential genes and the elaboration of high-throughput methods for the identification of gene function will be discussed.
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Affiliation(s)
- Julien Limenitakis
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland.
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17
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Genetic manipulation of Neospora caninum to express the bradyzoite-specific protein NcSAG4 in tachyzoites. Parasitology 2011; 138:472-80. [PMID: 21232176 DOI: 10.1017/s0031182010001666] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Neospora caninum is an apicomplexan parasite and the aetiological agent of bovine neosporosis, one of the main causes of reproductive failure worldwide. We have generated 2 independent transgenic knock-in clones, Nc-1SAG4c1.1 and Nc-1SAG4c2.1, that express the bradyzoite stage-specific protein NcSAG4 in the tachyzoite stage. These clones have similar growth rates in vitro as the wild-type (WT) strain Nc-1. Studies in a cerebral mouse model of infection revealed a slightly lower rate of detection of the transgenic strains in brains during the chronic phase of infection. However, a pregnant mouse model of infection revealed a reduction in the virulence of the Nc-1SAG4c1.1 strain despite the same tachyzoite expression of NcSAG4 and a similar anti-NcSAG4 response displayed by mice inoculated with Nc-1 SAG4c1.1 or Nc-1 SAG4c2.1 parasites. This behaviour may be related to the reduced ability of the Nc-1SAG4c1.1 parasites to invade host cells, which was observed in in vitro assays. The apparent reduction in persistence and the high growth rate of the transgenic strains, together with their constitutive expression of the protein NcSAG4, may be useful features for future immunoprophylaxis trials based on a safe live attenuated vaccine.
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18
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A new thrombospondin-related anonymous protein homologue in Neospora caninum (NcMIC2-like1). Parasitology 2010; 138:287-97. [DOI: 10.1017/s0031182010001290] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYNeospora caninum is an Apicomplexan protozoan that has the dog as a definitive host and cattle (among other animals) as intermediate hosts. It causes encephalopathy in dogs and abortion in cows, with significant loss in worldwide livestock. As any Apicomplexan, the parasite invades the cells using proteins contained in the phylum-specific organelles, like the micronemes, rhoptries and dense granules. The aim of this study was the characterization of a homologue (denominated NcMIC2-like1) of N. caninum thrombospondin-related anonymous protein (NcMIC2), a micronemal protein previously shown to be involved in the attachment and connection with the intracellular motor responsible for the active process of invasion. A polyclonal antiserum raised against the recombinant NcMIC2-like1 functional core (thrombospondin and integrin domains) recognized the native form of NcMIC2-like1, inhibited the in vitro invasion process and localized NcMIC2-like1 at the apical complex of the parasite by confocal immunofluorescence, indicating its micronemal localization. The new molecule, NcMIC2-like1, has features that differentiates it from NcMIC2 in a substantial way to be considered a homologue†.
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19
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Friedrich N, Santos JM, Liu Y, Palma AS, Leon E, Saouros S, Kiso M, Blackman MJ, Matthews S, Feizi T, Soldati-Favre D. Members of a novel protein family containing microneme adhesive repeat domains act as sialic acid-binding lectins during host cell invasion by apicomplexan parasites. J Biol Chem 2009; 285:2064-76. [PMID: 19901027 DOI: 10.1074/jbc.m109.060988] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Numerous intracellular pathogens exploit cell surface glycoconjugates for host cell recognition and entry. Unlike bacteria and viruses, Toxoplasma gondii and other parasites of the phylum Apicomplexa actively invade host cells, and this process critically depends on adhesins (microneme proteins) released onto the parasite surface from intracellular organelles called micronemes (MIC). The microneme adhesive repeat (MAR) domain of T. gondii MIC1 (TgMIC1) recognizes sialic acid (Sia), a key determinant on the host cell surface for invasion by this pathogen. By complementation and invasion assays, we demonstrate that TgMIC1 is one important player in Sia-dependent invasion and that another novel Sia-binding lectin, designated TgMIC13, is also involved. Using BLAST searches, we identify a family of MAR-containing proteins in enteroparasitic coccidians, a subclass of apicomplexans, including T. gondii, suggesting that all these parasites exploit sialylated glycoconjugates on host cells as determinants for enteric invasion. Furthermore, this protein family might provide a basis for the broad host cell range observed for coccidians that form tissue cysts during chronic infection. Carbohydrate microarray analyses, corroborated by structural considerations, show that TgMIC13, TgMIC1, and its homologue Neospora caninum MIC1 (NcMIC1) share a preference for alpha2-3- over alpha2-6-linked sialyl-N-acetyllactosamine sequences. However, the three lectins also display differences in binding preferences. Intense binding of TgMIC13 to alpha2-9-linked disialyl sequence reported on embryonal cells and relatively strong binding to 4-O-acetylated-Sia found on gut epithelium and binding of NcMIC1 to 6'sulfo-sialyl Lewis(x) might have implications for tissue tropism.
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Affiliation(s)
- Nikolas Friedrich
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva Centre Medical Universitaire, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland
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20
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Chen Z, Harb OS, Roos DS. In silico identification of specialized secretory-organelle proteins in apicomplexan parasites and in vivo validation in Toxoplasma gondii. PLoS One 2008; 3:e3611. [PMID: 18974850 PMCID: PMC2575384 DOI: 10.1371/journal.pone.0003611] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Accepted: 10/06/2008] [Indexed: 12/04/2022] Open
Abstract
Apicomplexan parasites, including the human pathogens Toxoplasma gondii and Plasmodium falciparum, employ specialized secretory organelles (micronemes, rhoptries, dense granules) to invade and survive within host cells. Because molecules secreted from these organelles function at the host/parasite interface, their identification is important for understanding invasion mechanisms, and central to the development of therapeutic strategies. Using a computational approach based on predicted functional domains, we have identified more than 600 candidate secretory organelle proteins in twelve apicomplexan parasites. Expression in transgenic T. gondii of eight proteins identified in silico confirms that all enter into the secretory pathway, and seven target to apical organelles associated with invasion. An in silico approach intended to identify possible host interacting proteins yields a dataset enriched in secretory/transmembrane proteins, including most of the antigens known to be engaged by apicomplexan parasites during infection. These domain pattern and projected interactome approaches significantly expand the repertoire of proteins that may be involved in host parasite interactions.
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Affiliation(s)
- ZhongQiang Chen
- Department of Biology, Penn Genomic Frontiers Institute, and the Graduate Program in Genomics and Computational Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Omar S. Harb
- Department of Biology, Penn Genomic Frontiers Institute, and the Graduate Program in Genomics and Computational Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (DSR); (OSH)
| | - David S. Roos
- Department of Biology, Penn Genomic Frontiers Institute, and the Graduate Program in Genomics and Computational Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (DSR); (OSH)
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21
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Jongert E, Verhelst D, Abady M, Petersen E, Gargano N. Protective Th1 immune responses against chronic toxoplasmosis induced by a protein–protein vaccine combination but not by its DNA–protein counterpart. Vaccine 2008; 26:5289-95. [DOI: 10.1016/j.vaccine.2008.07.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 07/08/2008] [Accepted: 07/14/2008] [Indexed: 11/26/2022]
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22
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Blumenschein TMA, Friedrich N, Childs RA, Saouros S, Carpenter EP, Campanero-Rhodes MA, Simpson P, Chai W, Koutroukides T, Blackman MJ, Feizi T, Soldati-Favre D, Matthews S. Atomic resolution insight into host cell recognition by Toxoplasma gondii. EMBO J 2007; 26:2808-20. [PMID: 17491595 PMCID: PMC1888667 DOI: 10.1038/sj.emboj.7601704] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 04/04/2007] [Indexed: 01/07/2023] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii, a member of the phylum Apicomplexa that includes Plasmodium spp., is one of the most widespread parasites and the causative agent of toxoplasmosis. Micronemal proteins (MICs) are released onto the parasite surface just before invasion of host cells and play important roles in host cell recognition, attachment and penetration. Here, we report the atomic structure for a key MIC, TgMIC1, and reveal a novel cell-binding motif called the microneme adhesive repeat (MAR). Using glycoarray analyses, we identified a novel interaction with sialylated oligosaccharides that resolves several prevailing misconceptions concerning TgMIC1. Structural studies of various complexes between TgMIC1 and sialylated oligosaccharides provide high-resolution insights into the recognition of sialylated oligosaccharides by a parasite surface protein. We observe that MAR domains exist in tandem repeats, which provide a highly specialized structure for glycan discrimination. Our work uncovers new features of parasite-receptor interactions at the early stages of host cell invasion, which will assist the design of new therapeutic strategies.
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Affiliation(s)
| | - Nikolas Friedrich
- Department of Microbiology and Genetics, Faculty of Medicine, University of Geneva CMU, Geneva, Switzerland
| | - Robert A Childs
- Glycosciences Laboratory, Division of Medicine, Imperial College London, Middlesex, UK
| | - Savvas Saouros
- Division of Molecular Biosciences, Imperial College London, London, UK
| | | | | | - Peter Simpson
- Division of Molecular Biosciences, Imperial College London, London, UK
| | - Wengang Chai
- Glycosciences Laboratory, Division of Medicine, Imperial College London, Middlesex, UK
| | | | - Michael J Blackman
- Division of Parasitology, National Institute for Medical Research, London, UK
| | - Ten Feizi
- Glycosciences Laboratory, Division of Medicine, Imperial College London, Middlesex, UK
| | - Dominique Soldati-Favre
- Department of Microbiology and Genetics, Faculty of Medicine, University of Geneva CMU, Geneva, Switzerland
| | - Stephen Matthews
- Division of Molecular Biosciences, Imperial College London, London, UK
- Division of Molecular Biosciences, Imperial College of Science, Technology and Medicine, South Kensington Campus, London SW7 2AZ, UK. Tel.: +44 207 594 5315; Fax: +44 207 594 5207; E-mail:
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23
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Periz J, Gill AC, Hunt L, Brown P, Tomley FM. The Microneme Proteins EtMIC4 and EtMIC5 of Eimeria tenella Form a Novel, Ultra-high Molecular Mass Protein Complex That Binds Target Host Cells. J Biol Chem 2007; 282:16891-8. [PMID: 17426025 DOI: 10.1074/jbc.m702407200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eimeria tenella, in common with other parasitic protozoa of the phylum Apicomplexa, invades host cells using an actinomyosin-powered "glideosome" complex and requires the secretion of adhesive proteins from the microneme organelles onto the parasite surface. Microneme proteins of E. tenella include EtMIC4, a transmembrane protein that has multiple thrombospondin type I domains and calcium-binding epidermal growth factor-like domains in its extracellular domain, and EtMIC5, a soluble protein composed of 11 tandemly repeated domains that belong to the plasminogen-apple-nematode superfamily. We show here that EtMIC4 and EtMIC5 interact to form an oligomeric, ultrahigh molecular mass protein complex. The complex was purified from lysed parasites by non-denaturing techniques, and the stoichiometry was shown to be [EtMIC4](2):[EtMIC5](1), with an octamer of EtMIC4 bound non-covalently to a tetramer of EtMIC5. The complex is formed within the parasite secretory pathway and is maintained after secretion onto the surface of the parasite. The purified complex binds to a number of epithelial cell lines in culture. Identification and characterization of this complex contributes to an overall understanding of the role of multimolecular protein complexes in specific interactions between pathogens and their hosts during infection.
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Affiliation(s)
- Javier Periz
- Institute for Animal Health, Compton, Newbury, Berkshire, RG20 7NN United Kingdom
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24
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Carruthers V, Boothroyd JC. Pulling together: an integrated model of Toxoplasma cell invasion. Curr Opin Microbiol 2007; 10:83-9. [PMID: 16837236 DOI: 10.1016/j.mib.2006.06.017] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 06/26/2006] [Indexed: 11/29/2022]
Abstract
The protozoan Toxoplasma gondii invades a wide array of animal cells using an actin/myosin-based motor complex to drive active penetration. This broad specificity implies that the parasite has developed a means of using a widely expressed receptor, many different receptors, or perhaps a receptor produced by T. gondii itself. Recently, there has been an explosion in identification of the molecules involved, including those that comprise the 'moving junction' that slides over the parasite as it invades. The emerging model is that invasion comprises at least seven steps that progressively increase the parasite's grip on the host surface, form the moving junction and enlist the motor complex to drive entry. These recent findings have led to new hypotheses regarding the parasite's broad host-specificity.
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Affiliation(s)
- Vern Carruthers
- W Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205-1918, USA.
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25
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Huynh MH, Carruthers VB. Toxoplasma MIC2 is a major determinant of invasion and virulence. PLoS Pathog 2006; 2:e84. [PMID: 16933991 PMCID: PMC1550269 DOI: 10.1371/journal.ppat.0020084] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Accepted: 07/10/2006] [Indexed: 11/18/2022] Open
Abstract
Like its apicomplexan kin, the obligate intracellular protozoan Toxoplasma gondii actively invades mammalian cells and uses a unique form of gliding motility. The recent identification of several transmembrane adhesive complexes, potentially capable of gripping external receptors and the sub-membrane actinomyosin motor, suggests that the parasite has multiple options for host-cell recognition and invasion. To test whether the transmembrane adhesin MIC2, together with its partner protein M2AP, participates in a major invasion pathway, we utilized a conditional expression system to introduce an anhydrotetracycline-responsive mic2 construct, allowing us to then knockout the endogenous mic2 gene. Conditional suppression of MIC2 provided the first opportunity to directly determine the role of this protein in infection. Reduced MIC2 expression resulted in mistrafficking of M2AP, markedly defective host-cell attachment and invasion, the loss of helical gliding motility, and the inability to support lethal infection in a murine model of acute toxoplasmosis. Survival of mice infected with MIC2-deficient parasites correlated with lower parasite burden in infected tissues, an attenuated inflammatory immune response, and induction of long-term protective immunity. Our findings demonstrate that the MIC2 protein complex is a major virulence determinant for Toxoplasma infection and that MIC2-deficient parasites constitute an effective live-attenuated vaccine for experimental toxoplasmosis.
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Affiliation(s)
- My-Hang Huynh
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Vern B Carruthers
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail:
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26
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Starnes GL, Jewett TJ, Carruthers VB, Sibley LD. Two Separate, Conserved Acidic Amino Acid Domains within the Toxoplasma gondii MIC2 Cytoplasmic Tail Are Required for Parasite Survival. J Biol Chem 2006; 281:30745-54. [PMID: 16923803 DOI: 10.1074/jbc.m606523200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apicomplexan parasites rely on actin-based motility to drive host cell invasion. Motility and invasion also require thrombospondin-related anonymous protein (TRAP) adhesins, which are secreted apically and translocated to the posterior end of the parasite before they are shed by the activity of a rhomboid protease. TRAP orthologs, including Toxoplasma gondii MIC2 (microneme protein 2), possess a short cytoplasmic tail, which is essential for motility. Previous studies have shown that aldolase forms a critical bridge between actin filaments and the cytoplasmic domains of MIC2 and TRAP. The cytoplasmic tails of TRAP family members harbor a conserved penultimate tryptophan, which is essential for aldolase binding, and clustered acidic residues. Herein, we determined the role of the conserved acidic residues by using alanine point mutants to investigate aldolase binding in vitro and to test functionality in the parasite. Our studies revealed two separate acidic residue clusters in the cytoplasmic domain of MIC2 that are essential for parasite survival. One region, located at the extreme C terminus, is required for the direct interaction with aldolase, whereas the second upstream acidic region is not necessary for aldolase binding but is nonetheless essential to parasite survival. Both acidic domains are conserved throughout TRAP orthologs, implicating a central role for these motifs in apicomplexan motility.
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Affiliation(s)
- G Lucas Starnes
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63130-1093, USA
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27
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Brydges SD, Zhou XW, Huynh MH, Harper JM, Mital J, Adjogble KDZ, Däubener W, Ward GE, Carruthers VB. Targeted deletion of MIC5 enhances trimming proteolysis of Toxoplasma invasion proteins. EUKARYOTIC CELL 2006; 5:2174-83. [PMID: 16980407 PMCID: PMC1694808 DOI: 10.1128/ec.00163-06] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Limited proteolysis of proteins transiently expressed on the surface of the opportunistic pathogen Toxoplasma gondii accompanies cell invasion and facilitates parasite migration across cell barriers during infection. However, little is known about what factors influence this specialized proteolysis or how these proteolytic events are regulated. Here we show that genetic ablation of the micronemal protein MIC5 enhances the normal proteolytic processing of several micronemal proteins secreted by Toxoplasma tachyzoites. Restoring MIC5 expression by genetic complementation reversed this phenotype, as did treatment with the protease inhibitor ALLN, which was previously shown to block the activity of a hypothetical parasite surface protease called MPP2. We show that, despite its lack of obvious membrane association signals, MIC5 occupies the parasite surface during invasion in the vicinity of the proteins affected by enhanced processing. Proteolysis of other secretory proteins, including GRA1, was also enhanced in MIC5 knockout parasites, indicating that the phenotype is not strictly limited to proteins derived from micronemes. Together, our findings suggest that MIC5 either directly regulates MPP2 activity or it influences MPP2's ability to access substrate cleavage sites on the parasite surface.
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Affiliation(s)
- Susannah D Brydges
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, MD 21205, USA
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28
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Harper JM, Huynh MH, Coppens I, Parussini F, Moreno S, Carruthers VB. A cleavable propeptide influences Toxoplasma infection by facilitating the trafficking and secretion of the TgMIC2-M2AP invasion complex. Mol Biol Cell 2006; 17:4551-63. [PMID: 16914527 PMCID: PMC1635346 DOI: 10.1091/mbc.e06-01-0064] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Propeptides regulate protein function and trafficking in many eukaryotic systems and have emerged as important features of regulated secretory proteins in parasites of the phylum Apicomplexa. Regulated protein secretion from micronemes and host cell invasion are inextricably linked and essential processes for the apicomplexan parasite Toxoplasma gondii. TgM2AP is a propeptide-containing microneme protein found in a heterohexameric complex with the microneme protein TgMIC2, a protein that has a demonstrated fundamental role in gliding motility and invasion. TgM2AP function is also central to these processes, because disruption of TgM2AP (m2apKO) results in secretory retention of TgMIC2, leading to reduced TgMIC2 secretion from the micronemes and impaired invasion. Because the TgM2AP propeptide is predicted to be processed in an intracellular site near where TgMIC2 is retained in m2apKO parasites, we hypothesized that the propeptide and its proteolytic removal influence trafficking and secretion of the complex. We found that proTgM2AP traffics through endosomal compartments and that deletion of the propeptide leads to defective trafficking of the complex within or near this site, resulting in aberrant processing and decreased secretion of TgMIC2, impaired invasion, and reduced virulence in vivo, mirroring the phenotypes observed in m2apKO parasites. In contrast, mutation of several cleavage site residues resulted in normal localization, but it affected the stability and secretion of the complex from the micronemes. Therefore, the propeptide and its cleavage site influence distinct aspects of TgMIC2-M2AP function, with both impacting the outcome of infection.
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Affiliation(s)
- Jill M. Harper
- *W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; and
| | - My-Hang Huynh
- *W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; and
| | - Isabelle Coppens
- *W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; and
| | - Fabiola Parussini
- *W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; and
| | - Silvia Moreno
- Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602
| | - Vern B. Carruthers
- *W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205; and
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29
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Mercier C, Adjogble KDZ, Däubener W, Delauw MFC. Dense granules: are they key organelles to help understand the parasitophorous vacuole of all apicomplexa parasites? Int J Parasitol 2006; 35:829-49. [PMID: 15978597 DOI: 10.1016/j.ijpara.2005.03.011] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 03/07/2005] [Accepted: 03/18/2005] [Indexed: 02/06/2023]
Abstract
Together with micronemes and rhoptries, dense granules are specialised secretory organelles of Apicomplexa parasites. Among Apicomplexa, Plasmodium represents a model of parasites propagated by way of an insect vector, whereas Toxoplasma is a model of food borne protozoa forming cysts. Through comparison of both models, this review summarises data accumulated over recent years on alternative strategies chosen by these parasites to develop within a parasitophorous vacuole and explores the role of dense granules in this process. One of the characteristics of the Plasmodium erythrocyte stages is to export numerous parasite proteins into both the host cell cytoplasm and/or plasma membrane via the vacuole used as a step trafficking compartment. Whether this feature can be correlated to few storage granules and a restricted number of dense granule proteins, is not yet clear. By contrast, the Toxoplasma developing vacuole is decorated by abundantly expressed dense granule proteins and is characterised by a network of membranous nanotubes. Although the exact function of most of these proteins remains currently unknown, recent data suggest that some of these dense granule proteins could be involved in building the intravacuolar membranous network. Conserved expression of the Toxoplasma dense granule proteins throughout most of the parasite stages suggests that they could also be key elements of the cyst formation.
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Affiliation(s)
- Corinne Mercier
- Institut Jean Roget, Université Joseph Fourier, CNRS UMR 5163, Place du Commandant Nal., 38700 La Tronche, France.
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30
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Heintzelman MB. Cellular and Molecular Mechanics of Gliding Locomotion in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 251:79-129. [PMID: 16939778 DOI: 10.1016/s0074-7696(06)51003-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gliding is a form of substrate-dependent cell locomotion exploited by a variety of disparate cell types. Cells may glide at rates well in excess of 1 microm/sec and do so without the gross distortion of cellular form typical of amoeboid crawling. In the absence of a discrete locomotory organelle, gliding depends upon an assemblage of molecules that links cytoplasmic motor proteins to the cell membrane and thence to the appropriate substrate. Gliding has been most thoroughly studied in the apicomplexan parasites, including Plasmodium and Toxoplasma, which employ a unique assortment of proteins dubbed the glideosome, at the heart of which is a class XIV myosin motor. Actin and myosin also drive the gliding locomotion of raphid diatoms (Bacillariophyceae) as well as the intriguing form of gliding displayed by the spindle-shaped cells of the primitive colonial protist Labyrinthula. Chlamydomonas and other flagellated protists are also able to abandon their more familiar swimming locomotion for gliding, during which time they recruit a motility apparatus independent of that driving flagellar beating.
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Affiliation(s)
- Matthew B Heintzelman
- Department of Biology, Program in Cell Biology and Biochemistry, Bucknell University, Lewisburg, PA 17837, USA
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31
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Baum J, Richard D, Healer J, Rug M, Krnajski Z, Gilberger TW, Green JL, Holder AA, Cowman AF. A conserved molecular motor drives cell invasion and gliding motility across malaria life cycle stages and other apicomplexan parasites. J Biol Chem 2005; 281:5197-208. [PMID: 16321976 DOI: 10.1074/jbc.m509807200] [Citation(s) in RCA: 263] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apicomplexan parasites constitute one of the most significant groups of pathogens infecting humans and animals. The liver stage sporozoites of Plasmodium spp. and tachyzoites of Toxoplasma gondii, the causative agents of malaria and toxoplasmosis, respectively, use a unique mode of locomotion termed gliding motility to invade host cells and cross cell substrates. This amoeboid-like movement uses a parasite adhesin from the thrombospondin-related anonymous protein (TRAP) family and a set of proteins linking the extracellular adhesin, via an actin-myosin motor, to the inner membrane complex. The Plasmodium blood stage merozoite, however, does not exhibit gliding motility. Here we show that homologues of the key proteins that make up the motor complex, including the recently identified glideosome-associated proteins 45 and 50 (GAP40 and GAP50), are present in P. falciparum merozoites and appear to function in erythrocyte invasion. Furthermore, we identify a merozoite TRAP homologue, termed MTRAP, a micronemal protein that shares key features with TRAP, including a thrombospondin repeat domain, a putative rhomboid-protease cleavage site, and a cytoplasmic tail that, in vitro, binds the actin-binding protein aldolase. Analysis of other parasite genomes shows that the components of this motor complex are conserved across diverse Apicomplexan genera. Conservation of the motor complex suggests that a common molecular mechanism underlies all Apicomplexan motility, which, given its unique properties, highlights a number of novel targets for drug intervention to treat major diseases of humans and livestock.
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Affiliation(s)
- Jake Baum
- Division of Infection and Immunity, The Walter & Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia
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32
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Zhou XW, Kafsack BFC, Cole RN, Beckett P, Shen RF, Carruthers VB. The opportunistic pathogen Toxoplasma gondii deploys a diverse legion of invasion and survival proteins. J Biol Chem 2005; 280:34233-44. [PMID: 16002397 PMCID: PMC1360232 DOI: 10.1074/jbc.m504160200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Host cell invasion is an essential step during infection by Toxoplasma gondii, an intracellular protozoan that causes the severe opportunistic disease toxoplasmosis in humans. Recent evidence strongly suggests that proteins discharged from Toxoplasma apical secretory organelles (micronemes, dense granules, and rhoptries) play key roles in host cell invasion and survival during infection. However, to date, only a limited number of secretory proteins have been discovered, and the full spectrum of effector molecules involved in parasite invasion and survival remains unknown. To address these issues, we analyzed a large cohort of freely released Toxoplasma secretory proteins by using two complementary methodologies, two-dimensional electrophoresis/mass spectrometry and liquid chromatography/electrospray ionization-tandem mass spectrometry (MudPIT, shotgun proteomics). Visualization of Toxoplasma secretory products by two-dimensional electrophoresis revealed approximately 100 spots, most of which were successfully identified by protein microsequencing or matrix-assisted laser desorption ionization-mass spectrometry analysis. Many proteins were present in multiple species suggesting they are subjected to substantial post-translational modification. Shotgun proteomic analysis of the secretory fraction revealed several additional products, including novel putative adhesive proteins, proteases, and hypothetical secretory proteins similar to products expressed by other related parasites including Plasmodium, the etiologic agent of malaria. A subset of novel proteins were re-expressed as fusions to yellow fluorescent protein, and this initial screen revealed shared and distinct localizations within secretory compartments of T. gondii tachyzoites. These findings provided a uniquely broad view of Toxoplasma secretory proteins that participate in parasite survival and pathogenesis during infection.
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Affiliation(s)
- Xing W Zhou
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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33
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Saouros S, Edwards-Jones B, Reiss M, Sawmynaden K, Cota E, Simpson P, Dowse TJ, Jäkle U, Ramboarina S, Shivarattan T, Matthews S, Soldati-Favre D. A novel galectin-like domain from Toxoplasma gondii micronemal protein 1 assists the folding, assembly, and transport of a cell adhesion complex. J Biol Chem 2005; 280:38583-91. [PMID: 16166092 DOI: 10.1074/jbc.c500365200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Immediately prior to invasion Toxoplasma gondii tachyzoites release a large number of micronemal proteins (TgMICs) that participate in host cell attachment and penetration. The TgMIC4-MIC1-MIC6 complex was the first to be identified in T. gondii and has been recently shown to be critical in invasion. This study establishes that the N-terminal thrombospondin type I repeat-like domains (TSR1-like) from TgMIC1 function as an independent adhesin as well as promoting association with TgMIC4. Using the newly solved three-dimensional structure of the C-terminal domain of TgMIC1 we have identified a novel Galectin-like fold that does not possess carbohydrate binding properties and redefines the architecture of TgMIC1. Instead, the TgMIC1 Galectin-like domain interacts and stabilizes TgMIC6, which provides the basis for a highly specific quality control mechanism for successful exit from the early secretory compartments and for subsequent trafficking of the complex to the micronemes.
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Affiliation(s)
- Savvas Saouros
- Department of Biological Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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34
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Shirley MW, Smith AL, Tomley FM. The Biology of Avian Eimeria with an Emphasis on their Control by Vaccination. ADVANCES IN PARASITOLOGY 2005; 60:285-330. [PMID: 16230106 DOI: 10.1016/s0065-308x(05)60005-x] [Citation(s) in RCA: 247] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies on the biology of the avian species of Eimeria are currently benefiting from the availability of a comprehensive sequence for the nuclear genome of Eimeria tenella. Allied to some recent advances in transgenic technologies and genetic approaches to identify protective antigens, some elements are now being assembled that should be helpful for the development of a new generation of vaccines. In the meantime, control of avian coccidiosis by vaccination represents a major success in the fight against infections caused by parasitic protozoa. Live vaccines that comprise defined populations of oocysts are used routinely and this form of vaccination is based upon the long-established fact that chickens infected with coccidial parasites rapidly develop protective immunity against challenge infections with the same species. Populations of wild-type Eimeria parasites were the basis of the first live vaccines introduced around 50 years ago and the more recent introduction of safer, live-attenuated, vaccines has had a significant impact on coccidiosis control in many areas of the world. In Europe the introduction of vaccination has coincided with declining drug efficacy (on account of drug resistance) and increasing concerns by consumers about the inclusion of in-feed medication and prospects for drug residues in meat. The use of attenuated vaccines throughout the world has also stimulated a greater interest in the vaccines that comprise wild-type parasites and, during the past 3 years worldwide, around 3x10(9) doses of each type of vaccine have been used. The need for only small numbers of live parasites to induce effective protective immunity and the recognition that Eimeria spp. are generally very potent immunogens has stimulated efforts to develop other types of vaccines. None has succeeded except for the licensing, within several countries in 2002, of a vaccine (CoxAbic vaccine; Abic, Israel) that protects via the maternal transfer of immunoglobulin to the young chick. Building on the success of viral vaccines that are delivered via the embryonating egg, an in ovo coccidiosis vaccine (Inovocox, Embrex Inc.) is currently in development. Following successful field trials in 2001, the product will be ready for Food and Drug Administration approval in 2005 and a manufacturing plant will begin production for sale in late 2005. Limited progress has been achieved towards the development of subunit or recombinant vaccines. No products are available and studies to identify potential antigens remain compromised by an absence of effective in vitro assays that correlate with the induction of protective immunity in the host. To date, only a relatively small portfolio of molecules has been evaluated for an ability to induce protection in vivo. Although Eimeria are effective immunogens, it is probable that to date none of the antigens that induce potent protective immune responses during the course of natural infection has been isolated.
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Affiliation(s)
- Martin W Shirley
- Institute for Animal Health, Compton Laboratory, Compton Nr Newbury, Berks RG20 7NN, UK.
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35
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Dowse T, Soldati D. Host cell invasion by the apicomplexans: the significance of microneme protein proteolysis. Curr Opin Microbiol 2004; 7:388-96. [PMID: 15358257 DOI: 10.1016/j.mib.2004.06.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Intracellular life-style has been adopted by many pathogens as a successful immune evasion mechanism. To gain entry to a large variety of host cells and to establish an intracellular niche, Toxoplasma gondii and other apicomplexans rely on an active process distinct from phagocytosis. Calcium-regulated secretion of microneme proteins and parasite actin polymerization together with the action of at least one myosin motor act in concert to generate the gliding motility necessary to propel the parasite into host cells. During this active penetration, host cell transmembrane proteins are excluded from the forming parasitophorous vacuole hence conferring the resistance to acidification and degradative fusion. Apicomplexans possess a large repertoire of microneme proteins that contribute to invasion, but their precise role and the level of functional redundancy remain to be evaluated. Remarkably, most microneme proteins are proteolytically cleaved during biogenesis and post-exocytosis. The significance of the processing events and the identification of the proteases implicated are the object of intensive investigations. These proteases may constitute potential drug targets for intervention against malaria and other diseases caused by these parasites.
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Affiliation(s)
- Timothy Dowse
- Department of Biological Sciences, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK
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