1
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Li B. Unwrap RAP1's Mystery at Kinetoplastid Telomeres. Biomolecules 2024; 14:67. [PMID: 38254667 PMCID: PMC10813129 DOI: 10.3390/biom14010067] [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: 12/06/2023] [Revised: 12/27/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024] Open
Abstract
Although located at the chromosome end, telomeres are an essential chromosome component that helps maintain genome integrity and chromosome stability from protozoa to mammals. The role of telomere proteins in chromosome end protection is conserved, where they suppress various DNA damage response machineries and block nucleolytic degradation of the natural chromosome ends, although the detailed underlying mechanisms are not identical. In addition, the specialized telomere structure exerts a repressive epigenetic effect on expression of genes located at subtelomeres in a number of eukaryotic organisms. This so-called telomeric silencing also affects virulence of a number of microbial pathogens that undergo antigenic variation/phenotypic switching. Telomere proteins, particularly the RAP1 homologs, have been shown to be a key player for telomeric silencing. RAP1 homologs also suppress the expression of Telomere Repeat-containing RNA (TERRA), which is linked to their roles in telomere stability maintenance. The functions of RAP1s in suppressing telomere recombination are largely conserved from kinetoplastids to mammals. However, the underlying mechanisms of RAP1-mediated telomeric silencing have many species-specific features. In this review, I will focus on Trypanosoma brucei RAP1's functions in suppressing telomeric/subtelomeric DNA recombination and in the regulation of monoallelic expression of subtelomere-located major surface antigen genes. Common and unique mechanisms will be compared among RAP1 homologs, and their implications will be discussed.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA;
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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2
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Touray AO, Sternlieb T, Isebe T, Cestari I. Identifying Antigenic Switching by Clonal Cell Barcoding and Nanopore Sequencing in Trypanosoma brucei. Bio Protoc 2023; 13:e4904. [PMID: 38156032 PMCID: PMC10751240 DOI: 10.21769/bioprotoc.4904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/01/2023] [Accepted: 11/01/2023] [Indexed: 12/30/2023] Open
Abstract
Many organisms alternate the expression of genes from large gene sets or gene families to adapt to environmental cues or immune pressure. The single-celled protozoan pathogen Trypanosoma brucei spp. periodically changes its homogeneous surface coat of variant surface glycoproteins (VSGs) to evade host antibodies during infection. This pathogen expresses one out of ~2,500 VSG genes at a time from telomeric expression sites (ESs) and periodically changes their expression by transcriptional switching or recombination. Attempts to track VSG switching have previously relied on genetic modifications of ES sequences with drug-selectable markers or genes encoding fluorescent proteins. However, genetic modifications of the ESs can interfere with the binding of proteins that control VSG transcription and/or recombination, thus affecting VSG expression and switching. Other approaches include Illumina sequencing of the VSG repertoire, which shows VSGs expressed in the population rather than cell switching; the Illumina short reads often limit the distinction of the large set of VSG genes. Here, we describe a methodology to study antigenic switching without modifications of the ES sequences. Our protocol enables the detection of VSG switching at nucleotide resolution using multiplexed clonal cell barcoding to track cells and nanopore sequencing to identify cell-specific VSG expression. We also developed a computational pipeline that takes DNA sequences and outputs VSGs expressed by cell clones. This protocol can be adapted to study clonal cell expression of large gene families in prokaryotes or eukaryotes. Key features • This protocol enables the analysis of variant surface glycoproteins (VSG) switching in T. brucei without modifying the expression site sequences. • It uses a streamlined computational pipeline that takes fastq DNA sequences and outputs expressed VSG genes by each parasite clone. • The protocol leverages the long reads sequencing capacity of the Oxford nanopore sequencing technology, which enables accurate identification of the expressed VSGs. • The protocol requires approximately eight to nine days to complete.
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Affiliation(s)
- Abdoulie O. Touray
- Institute of Parasitology, McGill University, Ste Anne de Bellevue, QC, Canada
- Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Tamara Sternlieb
- Institute of Parasitology, McGill University, Ste Anne de Bellevue, QC, Canada
| | - Tony Isebe
- Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Igor Cestari
- Institute of Parasitology, McGill University, Ste Anne de Bellevue, QC, Canada
- Division of Experimental Medicine, McGill University, Montreal, QC, Canada
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3
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Touray AO, Rajesh R, Isebe T, Sternlieb T, Loock M, Kutova O, Cestari I. PI(3,4,5)P3 allosteric regulation of repressor activator protein 1 controls antigenic variation in trypanosomes. eLife 2023; 12:RP89331. [PMID: 38019264 PMCID: PMC10686619 DOI: 10.7554/elife.89331] [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] [Indexed: 11/30/2023] Open
Abstract
African trypanosomes evade host immune clearance by antigenic variation, causing persistent infections in humans and animals. These parasites express a homogeneous surface coat of variant surface glycoproteins (VSGs). They transcribe one out of hundreds of VSG genes at a time from telomeric expression sites (ESs) and periodically change the VSG expressed by transcriptional switching or recombination. The mechanisms underlying the control of VSG switching and its developmental silencing remain elusive. We report that telomeric ES activation and silencing entail an on/off genetic switch controlled by a nuclear phosphoinositide signaling system. This system includes a nuclear phosphatidylinositol 5-phosphatase (PIP5Pase), its substrate PI(3,4,5)P3, and the repressor-activator protein 1 (RAP1). RAP1 binds to ES sequences flanking VSG genes via its DNA binding domains and represses VSG transcription. In contrast, PI(3,4,5)P3 binds to the N-terminus of RAP1 and controls its DNA binding activity. Transient inactivation of PIP5Pase results in the accumulation of nuclear PI(3,4,5)P3, which binds RAP1 and displaces it from ESs, activating transcription of silent ESs and VSG switching. The system is also required for the developmental silencing of VSG genes. The data provides a mechanism controlling reversible telomere silencing essential for the periodic switching in VSG expression and its developmental regulation.
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Affiliation(s)
- Abdoulie O Touray
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
- Division of Experimental Medicine, Department of Medicine, McGill UniversityMontrealCanada
| | - Rishi Rajesh
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
| | - Tony Isebe
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
| | - Tamara Sternlieb
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
| | - Mira Loock
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
| | - Oksana Kutova
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
| | - Igor Cestari
- Institute of Parasitology, McGill University, Sainte-Anne-de-BellevueMontrealCanada
- Division of Experimental Medicine, Department of Medicine, McGill UniversityMontrealCanada
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4
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Kieft R, Zhang Y, Yan H, Schmitz RJ, Sabatini R. Knockout of protein phosphatase 1 in Leishmania major reveals its role during RNA polymerase II transcription termination. Nucleic Acids Res 2023; 51:6208-6226. [PMID: 37194692 PMCID: PMC10325913 DOI: 10.1093/nar/gkad394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/26/2023] [Accepted: 05/04/2023] [Indexed: 05/18/2023] Open
Abstract
The genomes of kinetoplastids are organized into polycistronic transcription units that are flanked by a modified DNA base (base J, beta-D-glucosyl-hydroxymethyluracil). Previous work established a role of base J in promoting RNA polymerase II (Pol II) termination in Leishmania major and Trypanosoma brucei. We recently identified a PJW/PP1 complex in Leishmania containing a J-binding protein (JBP3), PP1 phosphatase 1, PP1 interactive-regulatory protein (PNUTS) and Wdr82. Analyses suggested the complex regulates transcription termination by recruitment to termination sites via JBP3-base J interactions and dephosphorylation of proteins, including Pol II, by PP1. However, we never addressed the role of PP1, the sole catalytic component, in Pol II transcription termination. We now demonstrate that deletion of the PP1 component of the PJW/PP1 complex in L. major, PP1-8e, leads to readthrough transcription at the 3'-end of polycistronic gene arrays. We show PP1-8e has in vitro phosphatase activity that is lost upon mutation of a key catalytic residue and associates with PNUTS via the conserved RVxF motif. Additionally, purified PJW complex with associated PP1-8e, but not complex lacking PP1-8e, led to dephosphorylation of Pol II, suggesting a direct role of PNUTS/PP1 holoenzymes in regulating transcription termination via dephosphorylating Pol II in the nucleus.
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Affiliation(s)
- Rudo Kieft
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA30602, USA
| | - Yang Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA30602, USA
| | - Haidong Yan
- Department of Genetics, University of Georgia, Athens, GA30602, USA
| | - Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, GA30602, USA
| | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA30602, USA
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5
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Faria J, Briggs EM, Black JA, McCulloch R. Emergence and adaptation of the cellular machinery directing antigenic variation in the African trypanosome. Curr Opin Microbiol 2022; 70:102209. [PMID: 36215868 DOI: 10.1016/j.mib.2022.102209] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/30/2022] [Accepted: 09/04/2022] [Indexed: 01/25/2023]
Abstract
Survival of the African trypanosome within its mammalian hosts, and hence transmission between hosts, relies upon antigenic variation, where stochastic changes in the composition of their protective variant-surface glycoprotein (VSG) coat thwart effective removal of the pathogen by adaptive immunity. Antigenic variation has evolved remarkable mechanistic complexity in Trypanosoma brucei, with switching of the VSG coat executed by either transcriptional or recombination reactions. In the former, a single T. brucei cell selectively transcribes one telomeric VSG transcription site, termed the expression site (ES), from a pool of around 15. Silencing of the active ES and activation of one previously silent ES can lead to a co-ordinated VSG coat switch. Outside the ESs, the T. brucei genome contains an enormous archive of silent VSG genes and pseudogenes, which can be recombined into the ES to execute a coat switch. Most such recombination involves gene conversion, including copying of a complete VSG and more complex reactions where novel 'mosaic' VSGs are formed as patchworks of sequences from several silent (pseudo)genes. Understanding of the cellular machinery that directs transcriptional and recombination VSG switching is growing rapidly and the emerging picture is of the use of proteins, complexes and pathways that are not limited to trypanosomes, but are shared across the wider grouping of kinetoplastids and beyond, suggesting co-option of widely used, core cellular reactions. We will review what is known about the machinery of antigenic variation and discuss if there remains the possibility of trypanosome adaptations, or even trypanosome-specific machineries, that might offer opportunities to impair this crucial parasite-survival process.
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Affiliation(s)
- Joana Faria
- York Biomedical Research Institute, Department of Biology, University of York, United Kingdom.
| | - Emma M Briggs
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom; Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, United Kingdom
| | - Jennifer A Black
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil; Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, United Kingdom
| | - Richard McCulloch
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, United Kingdom.
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6
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Faria JRC. A nuclear enterprise: zooming in on nuclear organization and gene expression control in the African trypanosome. Parasitology 2021; 148:1237-1253. [PMID: 33407981 PMCID: PMC8311968 DOI: 10.1017/s0031182020002437] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 12/17/2022]
Abstract
African trypanosomes are early divergent protozoan parasites responsible for high mortality and morbidity as well as a great economic burden among the world's poorest populations. Trypanosomes undergo antigenic variation in their mammalian hosts, a highly sophisticated immune evasion mechanism. Their nuclear organization and mechanisms for gene expression control present several conventional features but also a number of striking differences to the mammalian counterparts. Some of these unorthodox characteristics, such as lack of controlled transcription initiation or enhancer sequences, render their monogenic antigen transcription, which is critical for successful antigenic variation, even more enigmatic. Recent technological developments have advanced our understanding of nuclear organization and gene expression control in trypanosomes, opening novel research avenues. This review is focused on Trypanosoma brucei nuclear organization and how it impacts gene expression, with an emphasis on antigen expression. It highlights several dedicated sub-nuclear bodies that compartmentalize specific functions, whilst outlining similarities and differences to more complex eukaryotes. Notably, understanding the mechanisms underpinning antigen as well as general gene expression control is of great importance, as it might help designing effective control strategies against these organisms.
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Affiliation(s)
- Joana R. C. Faria
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, DundeeDD1 5EH, UK
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7
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Li B, Zhao Y. Regulation of Antigenic Variation by Trypanosoma brucei Telomere Proteins Depends on Their Unique DNA Binding Activities. Pathogens 2021; 10:pathogens10080967. [PMID: 34451431 PMCID: PMC8402208 DOI: 10.3390/pathogens10080967] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 01/17/2023] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis and regularly switches its major surface antigen, Variant Surface Glycoprotein (VSG), to evade the host immune response. Such antigenic variation is a key pathogenesis mechanism that enables T. brucei to establish long-term infections. VSG is expressed exclusively from subtelomere loci in a strictly monoallelic manner, and DNA recombination is an important VSG switching pathway. The integrity of telomere and subtelomere structure, maintained by multiple telomere proteins, is essential for T. brucei viability and for regulating the monoallelic VSG expression and VSG switching. Here we will focus on T. brucei TRF and RAP1, two telomere proteins with unique nucleic acid binding activities, and summarize their functions in telomere integrity and stability, VSG switching, and monoallelic VSG expression. Targeting the unique features of TbTRF and TbRAP1′s nucleic acid binding activities to perturb the integrity of telomere structure and disrupt VSG monoallelic expression may serve as potential therapeutic strategy against T. brucei.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Correspondence: (B.L.); (Y.Z.)
| | - Yanxiang Zhao
- Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen, China
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
- Correspondence: (B.L.); (Y.Z.)
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8
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Saha A, Gaurav AK, Pandya UM, Afrin M, Sandhu R, Nanavaty V, Schnur B, Li B. TbTRF suppresses the TERRA level and regulates the cell cycle-dependent TERRA foci number with a TERRA binding activity in its C-terminal Myb domain. Nucleic Acids Res 2021; 49:5637-5653. [PMID: 34048580 PMCID: PMC8191777 DOI: 10.1093/nar/gkab401] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/05/2021] [Accepted: 04/29/2021] [Indexed: 02/07/2023] Open
Abstract
Telomere repeat-containing RNA (TERRA) has been identified in multiple organisms including Trypanosoma brucei, a protozoan parasite that causes human African trypanosomiasis. T. brucei regularly switches its major surface antigen, VSG, to evade the host immune response. VSG is expressed exclusively from subtelomeric expression sites, and we have shown that telomere proteins play important roles in the regulation of VSG silencing and switching. In this study, we identify several unique features of TERRA and telomere biology in T. brucei. First, the number of TERRA foci is cell cycle-regulated and influenced by TbTRF, the duplex telomere DNA binding factor in T. brucei. Second, TERRA is transcribed by RNA polymerase I mainly from a single telomere downstream of the active VSG. Third, TbTRF binds TERRA through its C-terminal Myb domain, which also has the duplex DNA binding activity, in a sequence-specific manner and suppresses the TERRA level without affecting its half-life. Finally, levels of the telomeric R-loop and telomere DNA damage were increased upon TbTRF depletion. Overexpression of an ectopic allele of RNase H1 that resolves the R-loop structure in TbTRF RNAi cells can partially suppress these phenotypes, revealing an underlying mechanism of how TbTRF helps maintain telomere integrity.
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Affiliation(s)
- Arpita Saha
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Amit Kumar Gaurav
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Unnati M Pandya
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Marjia Afrin
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Ranjodh Sandhu
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Vishal Nanavaty
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Brittny Schnur
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.,Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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9
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Papadaki A, Tziouvara O, Kotopouli A, Koumarianou P, Doukas A, Rios P, Tardieux I, Köhn M, Boleti H. The Leishmania donovani LDBPK_220120.1 Gene Encodes for an Atypical Dual Specificity Lipid-Like Phosphatase Expressed in Promastigotes and Amastigotes; Substrate Specificity, Intracellular Localizations, and Putative Role(s). Front Cell Infect Microbiol 2021; 11:591868. [PMID: 33842381 PMCID: PMC8027504 DOI: 10.3389/fcimb.2021.591868] [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: 08/05/2020] [Accepted: 01/25/2021] [Indexed: 11/13/2022] Open
Abstract
The intracellular protozoan parasites of the Leishmania genus are responsible for Leishmaniases, vector borne diseases with a wide range of clinical manifestations. Leishmania (L.) donovani causes visceral leishmaniasis (kala azar), the most severe of these diseases. Along their biological cycle, Leishmania parasites undergo distinct developmental transitions including metacyclogenesis and differentiation of metacyclic promastigotes (MPs) to amastigotes. Metacyclogenesis inside the phlebotomine sandfly host's midgut converts the procyclic dividing promastigotes to non-dividing infective MPs eventually injected into the skin of mammalian hosts and phagocytosed by macrophages where the MPs are converted inside modified phagolysosomes to the intracellular amastigotes. These developmental transitions involve dramatic changes in cell size and shape and reformatting of the flagellum requiring thus membrane and cytoskeleton remodeling in which phosphoinositide (PI) signaling and metabolism must play central roles. This study reports on the LDBPK_220120.1 gene, the L. donovani ortholog of LmjF.22.0250 from L. major that encodes a phosphatase from the "Atypical Lipid Phosphatases" (ALPs) enzyme family. We confirmed the expression of the LDBPK_220120.1 gene product in both L. donovani promastigotes and axenic amastigotes and showed that it behaves in vitro as a Dual Specificity P-Tyr and monophosphorylated [PI(3)P and PI(4)P] PI phosphatase and therefore named it LdTyrPIP_22 (Leishmaniad onovani Tyrosine PI Phosphatase, gene locus at chromosome 22). By immunofluorescence confocal microscopy we localized the LdTyrPIP_22 in several intracellular sites in the cell body of L. donovani promastigotes and amastigotes and in the flagellum. A temperature and pH shift from 25°C to 37°C and from pH 7 to 5.5, induced a pronounced recruitment of LdTyrPIP_22 epitopes to the flagellar pocket and a redistribution around the nucleus. These results suggest possible role(s) for this P-Tyr/PI phosphatase in the regulation of processes initiated or upregulated by this temperature/pH shift that contribute to the developmental transition from MPs to amastigotes inside the mammalian host macrophages.
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Affiliation(s)
- Amalia Papadaki
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece
| | - Olympia Tziouvara
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece
| | - Anastasia Kotopouli
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece
| | - Petrina Koumarianou
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece.,Light Microscopy Unit, Hellenic Pasteur Institute, Athens, Greece
| | - Anargyros Doukas
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece
| | - Pablo Rios
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Isabelle Tardieux
- Team «Biomechanics of Host Parasite Interactions», Institut for Advanced BioSciences, Univ. Grenoble Alpes, Inserm U1209 - CNRS UMR 5309, 38700 La Tronche, France
| | - Maja Köhn
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Haralabia Boleti
- Intracellular Parasitism Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece.,Light Microscopy Unit, Hellenic Pasteur Institute, Athens, Greece
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10
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Pays E, Nolan DP. Genetic and immunological basis of human African trypanosomiasis. Curr Opin Immunol 2021; 72:13-20. [PMID: 33721725 PMCID: PMC8589022 DOI: 10.1016/j.coi.2021.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/11/2021] [Accepted: 02/19/2021] [Indexed: 12/11/2022]
Abstract
Human African trypanosomiasis, or sleeping sickness, results from infection by two subspecies of the protozoan flagellate parasite Trypanosoma brucei, termed Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, prevalent in western and eastern Africa respectively. These subspecies escape the trypanolytic potential of human serum, which efficiently acts against the prototype species Trypanosoma brucei brucei, responsible for the Nagana disease in cattle. We review the various strategies and components used by trypanosomes to counteract the immune defences of their host, highlighting the adaptive genomic evolution that occurred in both parasite and host to take the lead in this battle. The main parasite surface antigen, named Variant Surface Glycoprotein or VSG, appears to play a key role in different processes involved in the dialogue with the host.
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium.
| | - Derek P Nolan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland
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11
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Cestari I, Stuart K. The phosphoinositide regulatory network in Trypanosoma brucei: Implications for cell-wide regulation in eukaryotes. PLoS Negl Trop Dis 2020; 14:e0008689. [PMID: 33119588 PMCID: PMC7595295 DOI: 10.1371/journal.pntd.0008689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The unicellular eukaryote Trypanosoma brucei undergoes extensive cellular and developmental changes during its life cycle. These include regulation of mammalian stage surface antigen variation and surface composition changes between life stages; switching between glycolysis and oxidative phosphorylation; differential mRNA editing; and changes in posttranscriptional gene expression, protein trafficking, organellar function, and cell morphology. These diverse events are coordinated and controlled throughout parasite development, maintained in homeostasis at each life stage, and are essential for parasite survival in both the host and insect vector. Described herein are the enzymes and metabolites of the phosphatidylinositol (PI) cellular regulatory network, its integration with other cellular regulatory systems that collectively control and coordinate these numerous cellular processes, including cell development and differentiation and the many associated complex processes in multiple subcellular compartments. We conclude that this regulation is the product of the organization of these enzymes within the cellular architecture, their activities, metabolite fluxes, and responses to environmental changes via signal transduction and other processes. We describe a paradigm for how these enzymes and metabolites could function to control and coordinate multiple cellular functions. The significance of the PI system's regulatory functions in single-celled eukaryotes to metazoans and their potential as chemotherapeutic targets are indicated.
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Affiliation(s)
- Igor Cestari
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada
- Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
- * E-mail: (IC); (KS)
| | - Kenneth Stuart
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail: (IC); (KS)
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Cestari I. Phosphoinositide signaling and regulation in Trypanosoma brucei: Specialized functions in a protozoan pathogen. PLoS Pathog 2020; 16:e1008167. [PMID: 31895930 PMCID: PMC6939900 DOI: 10.1371/journal.ppat.1008167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Igor Cestari
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, Québec, Canada
- * E-mail:
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Sima N, McLaughlin EJ, Hutchinson S, Glover L. Escaping the immune system by DNA repair and recombination in African trypanosomes. Open Biol 2019; 9:190182. [PMID: 31718509 PMCID: PMC6893398 DOI: 10.1098/rsob.190182] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
African trypanosomes escape the mammalian immune response by antigenic variation-the periodic exchange of one surface coat protein, in Trypanosoma brucei the variant surface glycoprotein (VSG), for an immunologically distinct one. VSG transcription is monoallelic, with only one VSG being expressed at a time from a specialized locus, known as an expression site. VSG switching is a predominantly recombination-driven process that allows VSG sequences to be recombined into the active expression site either replacing the currently active VSG or generating a 'new' VSG by segmental gene conversion. In this review, we describe what is known about the factors that influence this process, focusing specifically on DNA repair and recombination.
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Affiliation(s)
- Núria Sima
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Emilia Jane McLaughlin
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Sebastian Hutchinson
- Trypanosome Cell Biology and INSERM U1201, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
| | - Lucy Glover
- Trypanosome Molecular Biology, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Docteur Roux, 75015 Paris, France
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Saha A, Nanavaty VP, Li B. Telomere and Subtelomere R-loops and Antigenic Variation in Trypanosomes. J Mol Biol 2019; 432:4167-4185. [PMID: 31682833 DOI: 10.1016/j.jmb.2019.10.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/02/2019] [Accepted: 10/21/2019] [Indexed: 12/12/2022]
Abstract
Trypanosoma brucei is a kinetoplastid parasite that causes African trypanosomiasis, which is fatal if left untreated. T. brucei regularly switches its major surface antigen, VSG, to evade the host immune responses. VSGs are exclusively expressed from subtelomeric expression sites (ESs) where VSG genes are flanked by upstream 70 bp repeats and downstream telomeric repeats. The telomere downstream of the active VSG is transcribed into a long-noncoding RNA (TERRA), which forms RNA:DNA hybrids (R-loops) with the telomeric DNA. At an elevated level, telomere R-loops cause more telomeric and subtelomeric double-strand breaks (DSBs) and increase VSG switching rate. In addition, stabilized R-loops are observed at the 70 bp repeats and immediately downstream of ES-linked VSGs in RNase H defective cells, which also have an increased amount of subtelomeric DSBs and more frequent VSG switching. Although subtelomere plasticity is expected to be beneficial to antigenic variation, severe defects in subtelomere integrity and stability increase cell lethality. Therefore, regulation of the telomere and 70 bp repeat R-loop levels is important for the balance between antigenic variation and cell fitness in T. brucei. In addition, the high level of the active ES transcription favors accumulation of R-loops at the telomere and 70 bp repeats, providing an intrinsic mechanism for local DSB formation, which is a strong inducer of VSG switching.
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Affiliation(s)
- Arpita Saha
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Science and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Vishal P Nanavaty
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Science and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Science and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA; Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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