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Fiama das Neves Ortiz S, Verdan R, Rocha GM, Miranda K, Benchimol M. The parabasal filaments of Trichomonas vaginalis: A new filament and observations using 0.8 nm-resolution scanning electron microscopy. J Struct Biol X 2024; 9:100099. [PMID: 38487378 PMCID: PMC10937234 DOI: 10.1016/j.yjsbx.2024.100099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 03/04/2024] [Indexed: 03/17/2024] Open
Abstract
Trichomonas vaginalis is the etiologic agent of trichomoniasis, the most common nonviral sexually transmitted infection worldwide, with an estimated 260 million new cases annually. T. vaginalis contains organelles common to all eukaryotic cells, uncommon cell structures such as hydrogenosomes, and a complex and elaborate cytoskeleton constituting the mastigont system. The mastigont system is mainly formed by several proteinaceous structures associated with basal bodies, the pelta-axostylar complex made of microtubules, and striated filaments named the costa and the parabasal filaments (PFs). Although the structural organization of trichomonad cytoskeletons has been analyzed using several techniques, observation using a new generation of scanning electron microscopes with a resolution exceeding 1 nm has allowed more detailed visualization of the three-dimensional organization of the mastigont system. In this study, we have investigated the cytoskeleton of T. vaginalis using a diverse range of scanning probe microscopy techniques, which were complemented by electron tomography and Fast-Fourier methods. This multi-modal approach has allowed us to characterize an unknown parabasal filament and reveal the ultrastructure of other striated fibers that have not been published before. Here, we show the differences in origin, striation pattern, size, localization, and additional details of the PFs, thus improving the knowledge of the cell biology of this parasite.
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Affiliation(s)
- Sharmila Fiama das Neves Ortiz
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Raphael Verdan
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Miranda Rocha
- Unidade de Pesquisa Urogenital, Centro Biomédico, Departamento de Anatomia, Universidade Estadual do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kildare Miranda
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- CENABIO - Centro Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem – Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Centro Multiusuário para Análise de Fenômenos Biomédicos, Universidade do Estado do Amazonas, Manaus, Brazil
| | - Marlene Benchimol
- CENABIO - Centro Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem – Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- UNIGRANRIO-Universidade da Grande Rio, Rio de Janeiro, Brazil
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2
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Ahmed M, Wheeler R, Týč J, Shafiq S, Sunter J, Vaughan S. Identification of 30 transition fibre proteins in Trypanosoma brucei reveals a complex and dynamic structure. J Cell Sci 2024; 137:jcs261692. [PMID: 38572631 PMCID: PMC11190437 DOI: 10.1242/jcs.261692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 03/26/2024] [Indexed: 04/05/2024] Open
Abstract
Transition fibres and distal appendages surround the distal end of mature basal bodies and are essential for ciliogenesis, but only a few of the proteins involved have been identified and functionally characterised. Here, through genome-wide analysis, we have identified 30 transition fibre proteins (TFPs) and mapped their arrangement in the flagellated eukaryote Trypanosoma brucei. We discovered that TFPs are recruited to the mature basal body before and after basal body duplication, with differential expression of five TFPs observed at the assembling new flagellum compared to the existing fixed-length old flagellum. RNAi-mediated depletion of 17 TFPs revealed six TFPs that are necessary for ciliogenesis and a further three TFPs that are necessary for normal flagellum length. We identified nine TFPs that had a detectable orthologue in at least one basal body-forming eukaryotic organism outside of the kinetoplastid parasites. Our work has tripled the number of known transition fibre components, demonstrating that transition fibres are complex and dynamic in their composition throughout the cell cycle, which relates to their essential roles in ciliogenesis and flagellum length regulation.
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Affiliation(s)
- Manu Ahmed
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
| | - Richard Wheeler
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford OX1 3SY, UK
| | - Jiří Týč
- Biology Centre CAS, Institute of Parasitology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic
| | - Shahaan Shafiq
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
| | - Jack Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
| | - Sue Vaughan
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK
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3
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Trépout S, Sgarra ML, Marco S, Ramm G. An introduction to scanning transmission electron microscopy for the study of protozoans. Mol Microbiol 2024; 121:659-670. [PMID: 38140856 DOI: 10.1111/mmi.15213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/29/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023]
Abstract
Since its inception in the 1930s, transmission electron microscopy (TEM) has been a powerful method to explore the cellular structure of parasites. TEM usually requires samples of <100 nm thick and with protozoans being larger than 1 μm, their study requires resin embedding and ultrathin sectioning. During the past decade, several new methods have been developed to improve, facilitate, and speed up the structural characterisation of biological samples, offering new imaging modalities for the study of protozoans. In particular, scanning transmission electron microscopy (STEM) can be used to observe sample sections as thick as 1 μm thus becoming an alternative to conventional TEM. STEM can also be performed under cryogenic conditions in combination with cryo-electron tomography providing access to the study of thicker samples in their native hydrated states in 3D. This method, called cryo-scanning transmission electron tomography (cryo-STET), was first developed in 2014. This review presents the basic concepts and benefits of STEM methods and provides examples to illustrate the potential for new insights into the structure and ultrastructure of protozoans.
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Affiliation(s)
- Sylvain Trépout
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Monash, Victoria, Australia
| | | | - Sergio Marco
- Vaccine CMC Development & Supply, Sanofi, Neuville sur Saône, France
| | - Georg Ramm
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Monash, Victoria, Australia
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4
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Verdan R, Patricio B, Weismuller G, Miranda K, de Souza W, Benchimol M, Gadelha AP. Characterization of a new extra-axonemal structure in the Giardia intestinalis flagella. J Struct Biol 2024; 216:108064. [PMID: 38280689 DOI: 10.1016/j.jsb.2024.108064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/05/2024] [Accepted: 01/18/2024] [Indexed: 01/29/2024]
Abstract
The inner structure of the flagella of Giardia intestinalis is similar to that of other organisms, consisting of nine pairs of outer microtubules and a central pair containing radial spokes. Although the 9+2 axonemal structure is conserved, it is not clear whether subregions, including the transition zone, are present in the flagella of this parasite. Giardia axonemes originate from basal bodies and have a lengthy cytosolic portion before becoming active flagella. The region of the emergence of the flagellum is not accompanied by any membrane specialization, as seen in other protozoa. Although Giardia is an intriguing model of study, few works focused on the ultrastructural analysis of the flagella of this parasite. Here, we analyzed the externalization region of the G. intestinalis flagella using ultra-high resolution scanning microscopy (with electrons and ions), atomic force microscopy in liquid medium, freeze fracture, and electron tomography. Our data show that this region possesses a distinctive morphological feature - it extends outward and takes on a ring-like shape. When the plasma membrane is removed, a structure surrounding the axoneme becomes visible in this region. This new extra-axonemal structure is observed in all pairs of flagella of trophozoites and remains attached to the axoneme even when the interconnections between the axonemal microtubules are disrupted. High-resolution scanning electron microscopy provided insights into the arrangement of this structure, contributing to the characterization of the externalization region of the flagella of this parasite.
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Affiliation(s)
- Raphael Verdan
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Beatriz Patricio
- Instituto Biomédico, Universidade Federal do Estado Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gilberto Weismuller
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Kildare Miranda
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Centro Nacional de Biologia Estrutural e Bioimagem e Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Centro Multiusuário para Análise de Fenômenos Biomédicos, Universidade do Estado do Amazonas, Manaus, Brazil
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Centro Nacional de Biologia Estrutural e Bioimagem e Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Centro Multiusuário para Análise de Fenômenos Biomédicos, Universidade do Estado do Amazonas, Manaus, Brazil
| | - Marlene Benchimol
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Centro Nacional de Biologia Estrutural e Bioimagem e Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil; Universidade do Grande Rio (UNIGRANRIO), Rio de Janeiro, RJ, Brazil
| | - Ana Paula Gadelha
- Universidade do Grande Rio (UNIGRANRIO), Rio de Janeiro, RJ, Brazil; Diretoria de Metrologia Científica e Industrial, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro, Rio de Janeiro, Brazil.
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5
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Moran AL, Louzao-Martinez L, Norris DP, Peters DJM, Blacque OE. Transport and barrier mechanisms that regulate ciliary compartmentalization and ciliopathies. Nat Rev Nephrol 2024; 20:83-100. [PMID: 37872350 DOI: 10.1038/s41581-023-00773-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2023] [Indexed: 10/25/2023]
Abstract
Primary cilia act as cell surface antennae, coordinating cellular responses to sensory inputs and signalling molecules that regulate developmental and homeostatic pathways. Cilia are therefore critical to physiological processes, and defects in ciliary components are associated with a large group of inherited pleiotropic disorders - known collectively as ciliopathies - that have a broad spectrum of phenotypes and affect many or most tissues, including the kidney. A central feature of the cilium is its compartmentalized structure, which imparts its unique molecular composition and signalling environment despite its membrane and cytosol being contiguous with those of the cell. Such compartmentalization is achieved via active transport pathways that bring protein cargoes to and from the cilium, as well as gating pathways at the ciliary base that establish diffusion barriers to protein exchange into and out of the organelle. Many ciliopathy-linked proteins, including those involved in kidney development and homeostasis, are components of the compartmentalizing machinery. New insights into the major compartmentalizing pathways at the cilium, namely, ciliary gating, intraflagellar transport, lipidated protein flagellar transport and ciliary extracellular vesicle release pathways, have improved our understanding of the mechanisms that underpin ciliary disease and associated renal disorders.
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Affiliation(s)
- Ailis L Moran
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Laura Louzao-Martinez
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.
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6
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Mill P, Christensen ST, Pedersen LB. Primary cilia as dynamic and diverse signalling hubs in development and disease. Nat Rev Genet 2023; 24:421-441. [PMID: 37072495 PMCID: PMC7615029 DOI: 10.1038/s41576-023-00587-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2023] [Indexed: 04/20/2023]
Abstract
Primary cilia, antenna-like sensory organelles protruding from the surface of most vertebrate cell types, are essential for regulating signalling pathways during development and adult homeostasis. Mutations in genes affecting cilia cause an overlapping spectrum of >30 human diseases and syndromes, the ciliopathies. Given the immense structural and functional diversity of the mammalian cilia repertoire, there is a growing disconnect between patient genotype and associated phenotypes, with variable severity and expressivity characteristic of the ciliopathies as a group. Recent technological developments are rapidly advancing our understanding of the complex mechanisms that control biogenesis and function of primary cilia across a range of cell types and are starting to tackle this diversity. Here, we examine the structural and functional diversity of primary cilia, their dynamic regulation in different cellular and developmental contexts and their disruption in disease.
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Affiliation(s)
- Pleasantine Mill
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland
| | | | - Lotte B Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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7
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Park K, Leroux MR. Composition, organization and mechanisms of the transition zone, a gate for the cilium. EMBO Rep 2022; 23:e55420. [PMID: 36408840 PMCID: PMC9724682 DOI: 10.15252/embr.202255420] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/08/2022] [Accepted: 10/31/2022] [Indexed: 11/22/2022] Open
Abstract
The cilium evolved to provide the ancestral eukaryote with the ability to move and sense its environment. Acquiring these functions required the compartmentalization of a dynein-based motility apparatus and signaling proteins within a discrete subcellular organelle contiguous with the cytosol. Here, we explore the potential molecular mechanisms for how the proximal-most region of the cilium, termed transition zone (TZ), acts as a diffusion barrier for both membrane and soluble proteins and helps to ensure ciliary autonomy and homeostasis. These include a unique complement and spatial organization of proteins that span from the microtubule-based axoneme to the ciliary membrane; a protein picket fence; a specialized lipid microdomain; differential membrane curvature and thickness; and lastly, a size-selective molecular sieve. In addition, the TZ must be permissive for, and functionally integrates with, ciliary trafficking systems (including intraflagellar transport) that cross the barrier and make the ciliary compartment dynamic. The quest to understand the TZ continues and promises to not only illuminate essential aspects of human cell signaling, physiology, and development, but also to unravel how TZ dysfunction contributes to ciliopathies that affect multiple organ systems, including eyes, kidney, and brain.
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Affiliation(s)
- Kwangjin Park
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
- Present address:
Terry Fox LaboratoryBC CancerVancouverBCCanada
- Present address:
Department of Medical GeneticsUniversity of British ColumbiaVancouverBCCanada
| | - Michel R Leroux
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
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8
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Sáez Conde J, Dean S. Structure, function and druggability of the African trypanosome flagellum. J Cell Physiol 2022; 237:2654-2667. [PMID: 35616248 PMCID: PMC9323424 DOI: 10.1002/jcp.30778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 04/20/2022] [Accepted: 04/25/2022] [Indexed: 11/29/2022]
Abstract
African trypanosomes are early branching protists that cause human and animal diseases, termed trypanosomiases. They have been under intensive study for more than 100 years and have contributed significantly to our understanding of eukaryotic biology. The combination of conserved and parasite‐specific features mean that their flagellum has gained particular attention. Here, we discuss the different structural features of the flagellum and their role in transmission and virulence. We highlight the possibilities of targeting flagellar function to cure trypanosome infections and help in the fight to eliminate trypanosomiases.
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Affiliation(s)
- Julia Sáez Conde
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Samuel Dean
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
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Ramanantsalama MR, Landrein N, Casas E, Salin B, Blancard C, Bonhivers M, Robinson DR, Dacheux D. TFK1, a basal body transition fibre protein that is essential for cytokinesis in Trypanosoma brucei. J Cell Sci 2022; 135:275643. [PMID: 35588197 DOI: 10.1242/jcs.259893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/12/2022] [Indexed: 11/20/2022] Open
Abstract
In Trypanosoma brucei, transition fibres (TF) form a nine-bladed pattern-like structure connecting the base of the flagellum to the flagellar pocket membrane. Despite the characterization of two TF proteins, CEP164C and TbRP2, little is known about the organization of these fibres. Here, we report the identification and characterization of the first kinetoplastid-specific TF protein named TFK1 (Tb927.6.1180). Bioinformatics and functional domain analysis identified three TFK1 distinct domains: an N-terminal domain of an unpredicted function, a coiled-coil domain involved in TFK1-TFK1 interaction and a C-terminal intrinsically disordered region potentially involved in protein interaction. Cellular immuno-localization showed that TFK1 is a newly identified basal body maturation marker. Further, using ultrastructure expansion and immuno-electron microscopies we localized CEP164C and TbRP2 at the TF and TFK1 on the distal appendage matrix of the TF. Importantly, RNAi knockdown of TFK1 in bloodstream form cells induced misplacement of basal bodies, a defect in the furrow or fold generation and eventually cell death. We hypothesize that TFK1 is a basal body positioning specific actor and a key regulator of cytokinesis in the bloodstream form Trypanosoma brucei.
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Affiliation(s)
| | - Nicolas Landrein
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Elina Casas
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Bénédicte Salin
- University of Bordeaux, CNRS, Microscopy Department IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Corinne Blancard
- University of Bordeaux, CNRS, Microscopy Department IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Mélanie Bonhivers
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Derrick R Robinson
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Denis Dacheux
- University of Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France.,Bordeaux INP, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
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10
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Dean S. Basic Biology of Trypanosoma brucei with Reference to the Development of Chemotherapies. Curr Pharm Des 2021; 27:1650-1670. [PMID: 33463458 DOI: 10.2174/1381612827666210119105008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/01/2020] [Accepted: 12/08/2020] [Indexed: 11/22/2022]
Abstract
Trypanosoma brucei are protozoan parasites that cause the lethal human disease African sleeping sickness and the economically devastating disease of cattle, Nagana. African sleeping sickness, also known as Human African Trypanosomiasis (HAT), threatens 65 million people and animal trypanosomiasis makes large areas of farmland unusable. There is no vaccine and licensed therapies against the most severe, late-stage disease are toxic, impractical and ineffective. Trypanosomes are transmitted by tsetse flies, and HAT is therefore predominantly confined to the tsetse fly belt in sub-Saharan Africa. They are exclusively extracellular and they differentiate between at least seven developmental forms that are highly adapted to host and vector niches. In the mammalian (human) host they inhabit the blood, cerebrospinal fluid (late-stage disease), skin, and adipose fat. In the tsetse fly vector they travel from the tsetse midgut to the salivary glands via the ectoperitrophic space and proventriculus. Trypanosomes are evolutionarily divergent compared with most branches of eukaryotic life. Perhaps most famous for their extraordinary mechanisms of monoallelic gene expression and antigenic variation, they have also been investigated because much of their biology is either highly unconventional or extreme. Moreover, in addition to their importance as pathogens, many researchers have been attracted to the field because trypanosomes have some of the most advanced molecular genetic tools and database resources of any model system. The following will cover just some aspects of trypanosome biology and how its divergent biochemistry has been leveraged to develop drugs to treat African sleeping sickness. This is by no means intended to be a comprehensive survey of trypanosome features. Rather, I hope to present trypanosomes as one of the most fascinating and tractable systems to do discovery biology.
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Affiliation(s)
- Samuel Dean
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
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11
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Central Apparatus, the Molecular Kickstarter of Ciliary and Flagellar Nanomachines. Int J Mol Sci 2021; 22:ijms22063013. [PMID: 33809498 PMCID: PMC7999657 DOI: 10.3390/ijms22063013] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 02/07/2023] Open
Abstract
Motile cilia and homologous organelles, the flagella, are an early evolutionarily invention, enabling primitive eukaryotic cells to survive and reproduce. In animals, cilia have undergone functional and structural speciation giving raise to typical motile cilia, motile nodal cilia, and sensory immotile cilia. In contrast to other cilia types, typical motile cilia are able to beat in complex, two-phase movements. Moreover, they contain many additional structures, including central apparatus, composed of two single microtubules connected by a bridge-like structure and assembling numerous complexes called projections. A growing body of evidence supports the important role of the central apparatus in the generation and regulation of the motile cilia movement. Here we review data concerning the central apparatus structure, protein composition, and the significance of its components in ciliary beating regulation.
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12
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Rachel R, Walther P, Maaßen C, Daberkow I, Matsuoka M, Witzgall R. Dual-axis STEM tomography at 200 kV: Setup, performance, limitations. J Struct Biol 2020; 211:107551. [DOI: 10.1016/j.jsb.2020.107551] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/14/2020] [Accepted: 06/13/2020] [Indexed: 12/18/2022]
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13
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Lemos M, Mallet A, Bertiaux E, Imbert A, Rotureau B, Bastin P. Timing and original features of flagellum assembly in trypanosomes during development in the tsetse fly. Parasit Vectors 2020; 13:169. [PMID: 32248844 PMCID: PMC7132888 DOI: 10.1186/s13071-020-04026-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/17/2020] [Indexed: 02/07/2023] Open
Abstract
Background Trypanosoma brucei exhibits a complex life-cycle alternating between tsetse flies and mammalian hosts. When parasites infect the fly, cells differentiate to adapt to life in various tissues, which is accompanied by drastic morphological and biochemical modifications especially in the proventriculus. This key step represents a bottleneck for salivary gland infection. Methods Here, we monitored flagellum assembly in trypanosomes during differentiation from the trypomastigote to the epimastigote stage, i.e. when the nucleus migrates to the posterior end of the cell, by using three-dimensional electron microscopy (focused ion beam scanning electron microscopy, FIB-SEM) and immunofluorescence assays. Results The combination of light and electron microscopy approaches provided structural and molecular evidence that the new flagellum is assembled while the nucleus migrates towards the posterior region of the body. Two major differences with well-known procyclic cells are reported. First, growth of the new flagellum begins when the associated basal body is found in a posterior position relative to the mature flagellum. Secondly, the new flagellum acquires its own flagellar pocket before rotating on the left side of the anterior-posterior axis. FIB-SEM revealed the presence of a structure connecting the new and mature flagellum and serial sectioning confirmed morphological similarities with the flagella connector of procyclic cells. We discuss the potential function of the flagella connector in trypanosomes from the proventriculus. Conclusions These findings show that T. brucei finely modulates its cytoskeletal components to generate highly variable morphologies.![]()
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Affiliation(s)
- Moara Lemos
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, 25, rue du Docteur Roux, 75015, Paris, France
| | - Adeline Mallet
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, 25, rue du Docteur Roux, 75015, Paris, France.,UtechS Ultrastructural Bioimaging (Ultrapole), C2RT, Institut Pasteur, 75015, Paris, France.,Sorbonne Université école doctorale Complexité du Vivant, ED 515, 7, quai Saint-Bernard, case 32, 75252, Paris Cedex 05, France
| | - Eloïse Bertiaux
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, 25, rue du Docteur Roux, 75015, Paris, France.,Sorbonne Université école doctorale Complexité du Vivant, ED 515, 7, quai Saint-Bernard, case 32, 75252, Paris Cedex 05, France
| | | | - Brice Rotureau
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, 25, rue du Docteur Roux, 75015, Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, 25, rue du Docteur Roux, 75015, Paris, France.
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Bertiaux E, Bastin P. Dealing with several flagella in the same cell. Cell Microbiol 2020; 22:e13162. [DOI: 10.1111/cmi.13162] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/19/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Eloïse Bertiaux
- Trypanosome Cell Biology Unit INSERM U1201, Institut Pasteur Paris France
- École Doctorale Complexité du Vivant Sorbonne Université Paris France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit INSERM U1201, Institut Pasteur Paris France
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Tomographic Collection of Block-Based Sparse STEM Images: Practical Implementation and Impact on the Quality of the 3D Reconstructed Volume. MATERIALS 2019; 12:ma12142281. [PMID: 31315199 PMCID: PMC6679239 DOI: 10.3390/ma12142281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 01/18/2023]
Abstract
The reduction of the electron dose in electron tomography of biological samples is of high significance to diminish radiation damages. Simulations have shown that sparse data collection can perform efficient electron dose reduction. Frameworks based on compressive-sensing or inpainting algorithms have been proposed to accurately reconstruct missing information in sparse data. The present work proposes a practical implementation to perform tomographic collection of block-based sparse images in scanning transmission electron microscopy. The method has been applied on sections of chemically-fixed and resin-embedded Trypanosoma brucei cells. There are 3D reconstructions obtained from various amounts of downsampling, which are compared and eventually the limits of electron dose reduction using this method are explored.
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16
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Mallet A, Bastin P. [Molecular motors and microtubules: which type of relationship?]. Med Sci (Paris) 2019; 35:302-304. [PMID: 31038106 DOI: 10.1051/medsci/2019062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Adeline Mallet
- Unité de technologie et de service UBI (Ultrastructural BioImaging), Institut Pasteur, 25, rue du Docteur Roux, 75015 Paris, France - Unité de biologie cellulaire des trypanosomes, Institut Pasteur, Inserm U1201, 25, rue du Docteur Roux, 75015 Paris, France - Sorbonne université, École doctorale complexité du vivant, ED 515, 7, quai Saint-Bernard, case 32, 75252 Paris Cedex 05, France
| | - Philippe Bastin
- Unité de biologie cellulaire des trypanosomes, Institut Pasteur, Inserm U1201, 25, rue du Docteur Roux, 75015 Paris, France
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Wachter S, Jung J, Shafiq S, Basquin J, Fort C, Bastin P, Lorentzen E. Binding of IFT22 to the intraflagellar transport complex is essential for flagellum assembly. EMBO J 2019; 38:embj.2018101251. [PMID: 30940671 DOI: 10.15252/embj.2018101251] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/28/2019] [Accepted: 03/04/2019] [Indexed: 01/08/2023] Open
Abstract
Intraflagellar transport (IFT) relies on motor proteins and the IFT complex to construct cilia and flagella. The IFT complex subunit IFT22/RabL5 has sequence similarity with small GTPases although the nucleotide specificity is unclear because of non-conserved G4/G5 motifs. We show that IFT22 specifically associates with G-nucleotides and present crystal structures of IFT22 in complex with GDP, GTP, and with IFT74/81. Our structural analysis unravels an unusual GTP/GDP-binding mode of IFT22 bypassing the classical G4 motif. The GTPase switch regions of IFT22 become ordered upon complex formation with IFT74/81 and mediate most of the IFT22-74/81 interactions. Structure-based mutagenesis reveals that association of IFT22 with the IFT complex is essential for flagellum construction in Trypanosoma brucei although IFT22 GTP-loading is not strictly required.
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Affiliation(s)
- Stefanie Wachter
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jamin Jung
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, Paris, France
| | - Shahaan Shafiq
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, Paris, France
| | - Jerome Basquin
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Cécile Fort
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, Institut Pasteur & INSERM U1201, Paris, France
| | - Esben Lorentzen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
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Amandine V, Cédric M, Sergio M, Patricia D. An ImageJ tool for simplified post-treatment of TEM phase contrast images (SPCI). Micron 2019; 121:90-98. [PMID: 30981155 DOI: 10.1016/j.micron.2019.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/18/2019] [Accepted: 01/18/2019] [Indexed: 11/17/2022]
Abstract
Tools for taking advantage of phase-contrast in transmission electron microscopy are of great interest for both biological and material sciences studies as shown by the recent use of phase plates and the development of holography. Nevertheless, these tools most often require highly qualified experts and access to advanced equipment that can only be considered after preliminary investigations. Here we propose to address this issue by the development of an ImageJ plugin that allow the retrieval of a phase image by simple numerical treatment applied to two defocused images. This treatment based on Tikhonov regularization requires the adjustment of a single parameter. Moreover, it is possible to use this approach on one-image. Although in that case the retrieved image gives only qualitative information, it is able to enhance the image contrast appropriately. This can be of interest for specimens producing low contrast images under the electron microscopes, such as some frozen hydrated biological samples or those sensible to electron radiation unsuitable for holographic studies.
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Affiliation(s)
- Verguet Amandine
- JEOL (Europe) SAS, allée de Giverny, F-78290 Croissy-sur-Seine, France; Institut Curie, PSL Research University, CNRS UMR9187, F-91405 Orsay, France; Université Paris-Sud, Université Paris-Saclay, INSERM U1196, F-91405 Orsay, France.
| | - Messaoudi Cédric
- Institut Curie, PSL Research University, CNRS UMR9187, F-91405 Orsay, France; Université Paris-Sud, Université Paris-Saclay, INSERM U1196, F-91405 Orsay, France
| | - Marco Sergio
- Institut Curie, PSL Research University, CNRS UMR9187, F-91405 Orsay, France; Université Paris-Sud, Université Paris-Saclay, INSERM U1196, F-91405 Orsay, France; Sanofi Pasteur, avenue Marcel Merieux, F-69280 Marcy L'Etoile, France
| | - Donnadieu Patricia
- Univ. Grenoble Alpes, CNRS, Grenoble INP, SIMaP, F-38000 Grenoble, France
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