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Chang R, Davydov A, Jaroenlak P, Budaitis B, Ekiert DC, Bhabha G, Prakash M. Energetics of the microsporidian polar tube invasion machinery. eLife 2024; 12:RP86638. [PMID: 38381133 PMCID: PMC10942582 DOI: 10.7554/elife.86638] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024] Open
Abstract
Microsporidia are eukaryotic, obligate intracellular parasites that infect a wide range of hosts, leading to health and economic burdens worldwide. Microsporidia use an unusual invasion organelle called the polar tube (PT), which is ejected from a dormant spore at ultra-fast speeds, to infect host cells. The mechanics of PT ejection are impressive. Anncaliia algerae microsporidia spores (3-4 μm in size) shoot out a 100-nm-wide PT at a speed of 300 μm/s, creating a shear rate of 3000 s-1. The infectious cargo, which contains two nuclei, is shot through this narrow tube for a distance of ∼60-140 μm (Jaroenlak et al, 2020) and into the host cell. Considering the large hydraulic resistance in an extremely thin tube and the low-Reynolds-number nature of the process, it is not known how microsporidia can achieve this ultrafast event. In this study, we use Serial Block-Face Scanning Electron Microscopy to capture 3-dimensional snapshots of A. algerae spores in different states of the PT ejection process. Grounded in these data, we propose a theoretical framework starting with a systematic exploration of possible topological connectivity amongst organelles, and assess the energy requirements of the resulting models. We perform PT firing experiments in media of varying viscosity, and use the results to rank our proposed hypotheses based on their predicted energy requirement. We also present a possible mechanism for cargo translocation, and quantitatively compare our predictions to experimental observations. Our study provides a comprehensive biophysical analysis of the energy dissipation of microsporidian infection process and demonstrates the extreme limits of cellular hydraulics.
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Affiliation(s)
- Ray Chang
- Department of Bioengineering, Stanford UniversityStanfordUnited States
| | - Ari Davydov
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Pattana Jaroenlak
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Breane Budaitis
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Damian C Ekiert
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, New York University School of MedicineNew YorkUnited States
| | - Gira Bhabha
- Department of Cell Biology, New York University School of MedicineNew YorkUnited States
| | - Manu Prakash
- Department of Bioengineering, Stanford UniversityStanfordUnited States
- Woods Institute for the Environment, Stanford UniversityStanfordUnited States
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Chang R, Davydov A, Jaroenlak P, Budaitis B, Ekiert DC, Bhabha G, Prakash M. Energetics of the Microsporidian Polar Tube Invasion Machinery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.17.524456. [PMID: 36711805 PMCID: PMC9884504 DOI: 10.1101/2023.01.17.524456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Microsporidia are eukaryotic, obligate intracellular parasites that infect a wide range of hosts, leading to health and economic burdens worldwide. Microsporidia use an unusual invasion organelle called the polar tube (PT), which is ejected from a dormant spore at ultra-fast speeds, to infect host cells. The mechanics of PT ejection are impressive. Anncaliia algerae microsporidia spores (3-4 μm in size) shoot out a 100-nm-wide PT at a speed of 300 μm/sec, creating a shear rate of 3000 sec-1. The infectious cargo, which contains two nuclei, is shot through this narrow tube for a distance of ~60-140 μm (Jaroenlak et al., 2020) and into the host cell. Considering the large hydraulic resistance in an extremely thin tube and the low-Reynolds-number nature of the process, it is not known how microsporidia can achieve this ultrafast event. In this study, we use Serial Block-Face Scanning Electron Microscopy to capture 3-dimensional snapshots of A. algerae spores in different states of the PT ejection process. Grounded in these data, we propose a theoretical framework starting with a systematic exploration of possible topological connectivity amongst organelles, and assess the energy requirements of the resulting models. We perform PT firing experiments in media of varying viscosity, and use the results to rank our proposed hypotheses based on their predicted energy requirement. We also present a possible mechanism for cargo translocation, and quantitatively compare our predictions to experimental observations. Our study provides a comprehensive biophysical analysis of the energy dissipation of microsporidian infection process and demonstrates the extreme limits of cellular hydraulics.
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Affiliation(s)
- Ray Chang
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
| | - Ari Davydov
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Pattana Jaroenlak
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Breane Budaitis
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Damian C. Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Manu Prakash
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
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Huang Q, Chen J, Lv Q, Long M, Pan G, Zhou Z. Germination of Microsporidian Spores: The Known and Unknown. J Fungi (Basel) 2023; 9:774. [PMID: 37504762 PMCID: PMC10381864 DOI: 10.3390/jof9070774] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/15/2023] [Accepted: 07/20/2023] [Indexed: 07/29/2023] Open
Abstract
Microsporidia are a large group of mysterious obligate intracellular eukaryotic parasites. The microsporidian spore can survive in the absence of nutrients for years under harsh conditions and germinate within seconds under the stimulation of environmental changes like pH and ions. During germination, microsporidia experience an increase in intrasporal osmotic pressure, which leads to an influx of water into the spore, followed by swelling of the polaroplasts and posterior vacuole, which eventually fires the polar filament (PF). Infectious sporoplasm was transported through the extruded polar tube (PT) and delivered into the host cell. Despite much that has been learned about the germination of microsporidia, there are still several major questions that remain unanswered, including: (i) There is still a lack of knowledge about the signaling pathways involved in spore germination. (ii) The germination of spores is not well understood in terms of its specific energetics. (iii) Limited understanding of how spores germinate and how the nucleus and membranes are rearranged during germination. (iv) Only a few proteins in the invasion organelles have been identified; many more are likely undiscovered. This review summarizes the major resolved and unresolved issues concerning the process of microsporidian spore germination.
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Affiliation(s)
- Qingyuan Huang
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Jie Chen
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Qing Lv
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Mengxian Long
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Guoqing Pan
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
| | - Zeyang Zhou
- State Key Laboratory of Resource Insects, Southwest University, Chongqing 400715, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing 400715, China
- Key Laboratory of Conservation and Utilization of Pollinator Insect of the upper reaches of the Yangtze River (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Chongqing Normal University, Chongqing 400047, China
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Weidner E, Overstreet R. Microsporidia Have a Peculiar Outer Membrane with Exterior Cytoplasmic Proteins. Acta Parasitol 2022; 67:49-54. [PMID: 34264441 DOI: 10.1007/s11686-021-00446-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/16/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE Most eukaryotic cells have a plasma membrane with glycoproteins on the outer leaflet and cytoplasmic proteins on the inner leaflet. However, the microsporidians examined have a peculiar outer membrane with cytoplasmic proteins on the surface. His study was to determine if this is true and identify the presence of key cytoplasmic proteins on the exterior of the sporoplasm and spore stages. METHODS Specific probes including GFP-labeled genes, antibodies, and electron microscopy were applied to studies on the sporoplasm and spore stages of different microsporidian species. RESULTS Cytoplasmic membrane proteins cadherin, intermediate filaments, dynactin p150Glued and tubulin were identified on the outer leaflet of the exterior membrane of the sporoplasm or spore stages of Spraguea americanus, Anncaliia algerae, Ameson michaelis and Thelohania sp. CONCLUSION The invasive sporoplasm stage of microsporidians acquires an outer membrane from a cytoplasmic organelle and it has been shown that the outside surface of this membrane bears cytoplasmic proteins. This membrane retains these cytoplasmic proteins even on the spore stage. For an intracellular parasite that locates directly within the cytoplasm of a host cell, the presence of these cytoplasmic proteins on the surface of the parasite appears to have a significant effect on the host's response.
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Affiliation(s)
- Earl Weidner
- Department of Biology, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.
| | - Robin Overstreet
- Gulf Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, Mississippi, 39564, USA
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Isolation and characterization of an endoparasite from the culture of oleaginous microalga Graesiella sp. WBG-1. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
Parasitism, aptly defined as one of the 'living-together' strategies (Trager, 1986), presents a dynamic system in which the parasite and its host are under evolutionary pressure to evolve new and specific adaptations, thus enabling the coexistence of the two closely interacting partners. Microsporidia are very frequently encountered obligatory intracellular protistan parasites that can infect both animals and some protists and are a consummate example of various aspects of the 'living-together' strategy. Microsporidia, relatives of fungi in the superkingdom Opisthokonta, belong to the relatively small group of parasites for which the host cell cytoplasm is the site of both reproduction and maturation. The structural and physiological reduction of their vegetative stage, together with the manipulation of host cell physiology, enables microsporidia to live in the cytosolic environment for most of their life cycle in a way resembling endocytobionts. The ability to form structurally complex spores and the invention and assembly of a unique injection mechanism enable microsporidia to disperse within host tissues and between host organisms, resulting in long-lasting infections. Microsporidia have adapted their genomes to the intracellular way of life, evolved strategies how to obtain nutrients directly from the host and how to manipulate not only the infected cells, but also the hosts themselves. The enormous variability of host organisms and their tissues provide microsporidian parasites a virtually limitless terrain for diversification and ecological expansion. This review attempts to present a general overview of microsporidia, emphasising some less known and/or more recently discovered facets of their biology.
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Abstract
Microsporidia are intracellular parasites of all major animal lineages and have a described diversity of over 1200 species and an actual diversity that is estimated to be much higher. They are important pathogens of mammals, and are now one of the most common infections among immunocompromised humans. Although related to fungi, microsporidia are atypical in genomic biology, cell structure and infection mechanism. Host cell infection involves the rapid expulsion of a polar tube from a dormant spore to pierce the host cell membrane and allow the direct transfer of the spore contents into the host cell cytoplasm. This intimate relationship between parasite and host is unique. It allows the microsporidia to be highly exploitative of the host cell environment and cause such diverse effects as the induction of hypertrophied cells to harbour prolific spore development, host sex ratio distortion and host cell organelle and microtubule reorganization. Genome sequencing has revealed that microsporidia have achieved this high level of parasite sophistication with radically reduced proteomes and with many typical eukaryotic pathways pared-down to what appear to be minimal functional units. These traits make microsporidia intriguing model systems for understanding the extremes of reductive parasite evolution and host cell manipulation.
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Affiliation(s)
- Bryony A P Williams
- Centre for Eukaryotic Evolutionary Microbiology, School of Biosciences, Stocker Road, University of Exeter, Exeter, Devon EX4 4QD, UK.
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Mathews A, Hotard A, Hale-Donze H. Innate immune responses to Encephalitozoon species infections. Microbes Infect 2009; 11:905-11. [PMID: 19573618 DOI: 10.1016/j.micinf.2009.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 06/23/2009] [Indexed: 11/29/2022]
Abstract
Microsporidia are obligate intracellular, eukaryotic fungi, which have gained recognition as opportunistic parasites in immunocompromised patients. Resistance to lethal microsporidia infections requires a Th1 immune response; how this protection is initiated against Encephalitozoon species is the focus of this review article.
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Affiliation(s)
- Amber Mathews
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences, Baton Rouge, LA 70803-1715, USA
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Abstract
PURPOSE OF REVIEW Microsporidiosis is an emerging and opportunistic infection associated with a wide range of clinical syndromes in humans. This review highlights the research on microsporidiosis in humans during the previous 2 years. RECENT FINDINGS The reduced and compact microsporidian genome has generated much interest for better understanding the evolution of these parasites, and comparative molecular phylogenetic studies continue to support a relationship between the microsporidia and fungi. Through increased awareness and improved diagnostics, microsporidiosis has been identified in a broader range of human populations that, in addition to persons with HIV infection, includes travelers, children, organ transplant recipients, and the elderly. SUMMARY Effective commercial therapies for Enterocytozoon bieneusi, the most common microsporidian species identified in humans, are still lacking, making the need to develop tissue culture and small animal models increasingly urgent. Environmental transport modeling and disinfection strategies are being addressed for improving water safety. Questions still exist about whether microsporidia infections remain persistent in asymptomatic immune-competent individuals, reactivate during conditions of immune compromise, or may be transmitted to others at risk, such as during pregnancy or through organ donation. Reliable serological diagnostic methods are needed to supplement polymerase chain reaction or histochemistry when spore shedding may be sporadic.
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Affiliation(s)
- Elizabeth S Didier
- Division of Microbiology, Tulane National Primate Research Center, Covington, Louisiana 70433, USA.
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Leitch GJ, Ward TL, Shaw AP, Newman G. Apical spore phagocytosis is not a significant route of infection of differentiated enterocytes by Encephalitozoon intestinalis. Infect Immun 2005; 73:7697-704. [PMID: 16239574 PMCID: PMC1273909 DOI: 10.1128/iai.73.11.7697-7704.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Encephalitozoon intestinalis is a microsporidian species that infects the intestinal mucosal epithelium, primarily in immunodeficient individuals. The present study employed undifferentiated and differentiated human colonic carcinoma cell lines to determine if this parasite species infected polarized epithelial cells by spore phagocytosis or by impalement with the deployed spore polar tube. Apical surface spore attachment differed between cell lines such that SW480>HT-29>Caco-2>HCT-8, with attachment being greater to undifferentiated Caco-2 cells than differentiated cells and greater to partially differentiated HCT-8 cells than differentiated HCT-8 cells. Attachment was inhibited by chondroitin sulfate A, suggesting that it was mediated by host cell sulfated glycoaminoglycans. Infection rates 3 days postinfection paralleled spore attachment in the various cell lines. The undifferentiated cell line SW480 and undifferentiated Caco-2 and HCT-8 cells exhibited modest spore phagocytosis while the more differentiated cell line HT29 and differentiated Caco-2 and HCT-8 cells did not. All cell lines were impaled by the polar tubes of germinating spores. When normalized to the number of spores attached to the apical membrane, such impalement was greatest in the more differentiated Caco-2 and HCT-8 cells. The host cell apical surface influenced parasite spore germination, as in populations of large undifferentiated Caco-2 cells to which >3 spores had attached, the frequency distribution of the percentages of spores germinated per cell was bimodal, indicating that the surface of some cells favored germination, while others did not. This study suggests that phagocytosis is not a biologically significant mode of infection in differentiated intestinal epithelial cells.
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Affiliation(s)
- Gordon J Leitch
- Department of Physiology, Morehouse School of Medicine, 720 Westview Dr., Atlanta, GA 30310, USA.
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Xu Y, Weiss LM. The microsporidian polar tube: a highly specialised invasion organelle. Int J Parasitol 2005; 35:941-53. [PMID: 16005007 PMCID: PMC3109658 DOI: 10.1016/j.ijpara.2005.04.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/28/2005] [Accepted: 04/05/2005] [Indexed: 11/30/2022]
Abstract
All of the members of the Microsporidia possess a unique, highly specialised structure, the polar tube. This article reviews the available data on the organisation, structure and function of this invasion organelle. It was over 100 years ago that Thelohan accurately described the microsporidian polar tube and the triggering of its discharge. In the spore, the polar tube is connected at the anterior end, and then coils around the sporoplasm. Upon appropriate environmental stimulation the polar tube rapidly discharges out of the spore pierces a cell membrane and serves as a conduit for sporoplasm passage into the new host cell. The mechanism of germination of spores, however, remains to be definitively determined. In addition, further studies on the characterisation of the early events in the rupture of the anterior attachment complex, eversion of the polar tube as well as the mechanism of host cell attachment and penetration are needed in order to clarify the function and assembly of this structure. The application of immunological and molecular techniques has resulted in the identification of three polar tube proteins referred to as PTP1, PTP2 and PTP3. The interactions of these identified proteins in the formation and function of the polar tube remain to be determined. Data suggest that PTP1 is an O-mannosylated glycoprotein, a post-translational modification that may be important for its function. With the availability of the Encephalitozoon cuniculi genome it is now possible to apply proteomic techniques to the characterisation of the components of the microsporidian spore and invasion organelle.
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Affiliation(s)
- Yanji Xu
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Room 504 Forchheimer Building, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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