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Mohammed M, Dziedziech A, Macedo D, Huppertz F, Veith Y, Postel Z, Christ E, Scheytt R, Slotte T, Henriksson J, Ankarklev J. Single-cell transcriptomics reveal transcriptional programs underlying male and female cell fate during Plasmodium falciparum gametocytogenesis. Nat Commun 2024; 15:7177. [PMID: 39187486 PMCID: PMC11347709 DOI: 10.1038/s41467-024-51201-3] [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: 06/02/2023] [Accepted: 08/01/2024] [Indexed: 08/28/2024] Open
Abstract
The Plasmodium falciparum life cycle includes obligate transition between a human and mosquito host. Gametocytes are responsible for transmission from the human to the mosquito vector where gamete fusion followed by meiosis occurs. To elucidate how male and female gametocytes differentiate in the absence of sex chromosomes, we perform FACS-based cell enrichment of a P. falciparum gametocyte reporter line followed by single-cell RNA-seq. In our analyses we define the transcriptional programs and predict candidate driver genes underlying male and female development, including genes from the ApiAP2 family of transcription factors. A motif-driven, gene regulatory network analysis indicates that AP2-G5 specifically modulates male development. Additionally, genes linked to the inner membrane complex, involved in morphological changes, are uniquely expressed in the female lineage. The transcriptional programs of male and female development detailed herein allow for further exploration of the evolution of sex in eukaryotes and provide targets for future development of transmission blocking therapies.
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Affiliation(s)
- Mubasher Mohammed
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
| | - Alexis Dziedziech
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
- Department of Global Health, Institut Pasteur, 25-28 Rue du Docteur Roux, Paris, France
| | - Diego Macedo
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Frederik Huppertz
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Ylva Veith
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Zoé Postel
- Department of Ecology, Environment and Plant Science, Stockholm University, Stockholm, Sweden
| | - Elena Christ
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Richard Scheytt
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Science, Stockholm University, Stockholm, Sweden
| | - Johan Henriksson
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Integrated Science Lab, Umeå University, Umeå, Sweden
| | - Johan Ankarklev
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
- Microbial Single Cell Genomics Facility, SciLifeLab, Biomedical Center (BMC) Uppsala University, Uppsala, Sweden.
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2
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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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, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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3
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Contreras SM, Zambrano Siri RT, Rivera EM, Cristaldi C, Kamenetzky L, Kim K, Clemente M, Ocampo J, Vanagas L, Angel SO. Architecture, Chromatin and Gene Organization of Toxoplasma gondii Subtelomeres. EPIGENOMES 2022; 6:29. [PMID: 36135316 PMCID: PMC9498087 DOI: 10.3390/epigenomes6030029] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022] Open
Abstract
Subtelomeres (ST) are chromosome regions that separate telomeres from euchromatin and play relevant roles in various biological processes of the cell. While their functions are conserved, ST structure and genetic compositions are unique to each species. This study aims to identify and characterize the subtelomeric regions of the 13 Toxoplasma gondii chromosomes of the Me49 strain. Here, STs were defined at chromosome ends based on poor gene density. The length of STs ranges from 8.1 to 232.4 kbp, with a gene density of 0.049 genes/kbp, lower than the Me49 genome (0.15 kbp). Chromatin organization showed that H3K9me3, H2A.X, and H3.3 are highly enriched near telomeres and the 5' end of silenced genes, decaying in intensity towards euchromatin. H3K4me3 and H2A.Z/H2B.Z are shown to be enriched in the 5' end of the ST genes. Satellite DNA was detected in almost all STs, mainly the sat350 family and a novel satellite named sat240. Beyond the STs, only short dispersed fragments of sat240 and sat350 were found. Within STs, there were 12 functional annotated genes, 59 with unknown functions (Hypothetical proteins), 15 from multigene FamB, and 13 from multigene family FamC. Some genes presented low interstrain synteny associated with the presence of satellite DNA. Orthologues of FamB and FamC were also detected in Neospora caninum and Hammondia hammondi. A re-analysis of previous transcriptomic data indicated that ST gene expression is strongly linked to the adaptation to different situations such as extracellular passage (evolve and resequencing study) and changes in metabolism (lack of acetyl-CoA cofactor). In conclusion, the ST region of the T. gondii chromosomes was defined, the STs genes were determined, and it was possible to associate them with high interstrain plasticity and a role in the adaptability of T. gondii to environmental changes.
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Affiliation(s)
- Susana M. Contreras
- Laboratorio de Parasitología Molecular, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
| | - Romina T. Zambrano Siri
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI-CONICET), Buenos Aires C1428ADN, Argentina
| | - Elías M. Rivera
- Laboratorio de Parasitología Molecular, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
| | - Constanza Cristaldi
- Laboratorio de Parasitología Molecular, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
| | - Laura Kamenetzky
- Laboratorio de Genómica y Bioinformática de Patógenos, iB3|Instituto de Biociencias, Biotecnología y Biología traslacional, Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EHA, Argentina
| | - Kami Kim
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33602, USA
| | - Marina Clemente
- Laboratorio de Molecular Farming y Vacunas, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
| | - Josefina Ocampo
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI-CONICET), Buenos Aires C1428ADN, Argentina
| | - Laura Vanagas
- Laboratorio de Parasitología Molecular, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
| | - Sergio O. Angel
- Laboratorio de Parasitología Molecular, Instituto Tecnológico Chascomús (INTECH), Universidad Nacional de General San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Chascomús 7130, Argentina
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4
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Engel JA, Norris EL, Gilson P, Przyborski J, Shonhai A, Blatch GL, Skinner-Adams TS, Gorman J, Headlam M, Andrews KT. Proteomic analysis of Plasmodium falciparum histone deacetylase 1 complex proteins. Exp Parasitol 2019; 198:7-16. [PMID: 30682336 DOI: 10.1016/j.exppara.2019.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/01/2018] [Accepted: 01/20/2019] [Indexed: 01/12/2023]
Abstract
Plasmodium falciparum histone deacetylases (PfHDACs) are an important class of epigenetic regulators that alter protein lysine acetylation, contributing to regulation of gene expression and normal parasite growth and development. PfHDACs are therefore under investigation as drug targets for malaria. Despite this, our understanding of the biological roles of these enzymes is only just beginning to emerge. In higher eukaryotes, HDACs function as part of multi-protein complexes and act on both histone and non-histone substrates. Here, we present a proteomics analysis of PfHDAC1 immunoprecipitates, identifying 26 putative P. falciparum complex proteins in trophozoite-stage asexual intraerythrocytic parasites. The co-migration of two of these (P. falciparum heat shock proteins 70-1 and 90) with PfHDAC1 was validated using Blue Native PAGE combined with Western blot. These data provide a snapshot of possible PfHDAC1 interactions and a starting point for future studies focused on elucidating the broader function of PfHDACs in Plasmodium parasites.
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Affiliation(s)
- Jessica A Engel
- Griffith Institute for Drug Discovery, Griffith University, Queensland, Australia
| | - Emma L Norris
- QIMR Berghofer Medical Research Institute, Queensland, Australia
| | - Paul Gilson
- Burnet Institute, Monash University, Victoria, Australia
| | - Jude Przyborski
- Centre of Infectious Diseases, Parasitology, University Hospital Heidelberg, Germany
| | - Addmore Shonhai
- Biochemistry Department, University of Venda, Thohoyandou, South Africa
| | - Gregory L Blatch
- The Vice Chancellery, The University of Notre Dame Australia, Fremantle, WA, Australia
| | - Tina S Skinner-Adams
- Griffith Institute for Drug Discovery, Griffith University, Queensland, Australia
| | - Jeffrey Gorman
- QIMR Berghofer Medical Research Institute, Queensland, Australia
| | | | - Katherine T Andrews
- Griffith Institute for Drug Discovery, Griffith University, Queensland, Australia.
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5
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Anas M, Sharma R, Dhamodharan V, Pradeepkumar PI, Manhas A, Srivastava K, Ahmed S, Kumar N. Investigating Pharmacological Targeting of G-Quadruplexes in the Human Malaria Parasite. Biochemistry 2017; 56:6691-6699. [DOI: 10.1021/acs.biochem.7b00964] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Mohammad Anas
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - Richa Sharma
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - V. Dhamodharan
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - P. I. Pradeepkumar
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - Ashan Manhas
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - Kumkum Srivastava
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
| | - Shakil Ahmed
- Molecular
and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
| | - Niti Kumar
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
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6
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Mohanty P, Gupta A, Bhatnagar S. Modeling of Plasmodium falciparum Telomerase Reverse Transcriptase Ternary Complex: Repurposing of Nucleoside Analog Inhibitors. Assay Drug Dev Technol 2015; 13:628-37. [PMID: 26690766 DOI: 10.1089/adt.2015.29013.pmodrrr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Plasmodium falciparum telomerase reverse transcriptase (PfTERT) is a ribonucleoprotein that assists the maintenance of the telomeric ends of chromosomes by reverse transcription of its own RNA subunit. It represents an attractive therapeutic target for eradication of the plasmodial parasite at the asexual liver stage. Automated modeling using MUSTER and knowledge-based techniques were used to obtain a three-dimensional model of the active site of reverse transcriptase domain of PfTERT, which is responsible for catalyzing the addition of incoming dNTPs to the growing DNA strand in presence of divalent magnesium ions. Further, the ternary complex of the active site of PfTERT bound to a DNA-RNA duplex was also modeled using Haddock server and represents the functional form of the enzyme. Initially, established nucleoside analog inhibitors of PfTERT, AZTTP, and ddGTP were docked in the modeled binding site of the PfTERT ternary complex using AutoDock v4.2. Subsequently, docking studies were carried out with 14 approved nucleoside analog inhibitors. Docking studies predicted that floxuridine, gemcitabine, stavudine, and vidarabine have high affinity for the PfTERT ternary complex. Further analysis on the basis of known side effects led us to propose repositioning of vidarabine as a suitable drug candidate for inhibition of PfTERT.
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Affiliation(s)
- Pallavi Mohanty
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , Dwarka, New Delhi, India
| | - Akanksha Gupta
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , Dwarka, New Delhi, India
| | - Sonika Bhatnagar
- Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , Dwarka, New Delhi, India
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7
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Baranasic D, Oppermann T, Cheaib M, Cullum J, Schmidt H, Simon M. Genomic characterization of variable surface antigens reveals a telomere position effect as a prerequisite for RNA interference-mediated silencing in Paramecium tetraurelia. mBio 2014; 5:e01328. [PMID: 25389173 PMCID: PMC4235209 DOI: 10.1128/mbio.01328-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 06/24/2014] [Indexed: 12/02/2022] Open
Abstract
UNLABELLED Antigenic or phenotypic variation is a widespread phenomenon of expression of variable surface protein coats on eukaryotic microbes. To clarify the mechanism behind mutually exclusive gene expression, we characterized the genetic properties of the surface antigen multigene family in the ciliate Paramecium tetraurelia and the epigenetic factors controlling expression and silencing. Genome analysis indicated that the multigene family consists of intrachromosomal and subtelomeric genes; both classes apparently derive from different gene duplication events: whole-genome and intrachromosomal duplication. Expression analysis provides evidence for telomere position effects, because only subtelomeric genes follow mutually exclusive transcription. Microarray analysis of cultures deficient in Rdr3, an RNA-dependent RNA polymerase, in comparison to serotype-pure wild-type cultures, shows cotranscription of a subset of subtelomeric genes, indicating that the telomere position effect is due to a selective occurrence of Rdr3-mediated silencing in subtelomeric regions. We present a model of surface antigen evolution by intrachromosomal gene duplication involving the maintenance of positive selection of structurally relevant regions. Further analysis of chromosome heterogeneity shows that alternative telomere addition regions clearly affect transcription of closely related genes. Consequently, chromosome fragmentation appears to be of crucial importance for surface antigen expression and evolution. Our data suggest that RNAi-mediated control of this genetic network by trans-acting RNAs allows rapid epigenetic adaptation by phenotypic variation in combination with long-term genetic adaptation by Darwinian evolution of antigen genes. IMPORTANCE Alternating surface protein structures have been described for almost all eukaryotic microbes, and a broad variety of functions have been described, such as virulence factors, adhesion molecules, and molecular camouflage. Mechanisms controlling gene expression of variable surface proteins therefore represent a powerful tool for rapid phenotypic variation across kingdoms in pathogenic as well as free-living eukaryotic microbes. However, the epigenetic mechanisms controlling synchronous expression and silencing of individual genes are hardly understood. Using the ciliate Paramecium tetraurelia as a (epi)genetic model, we showed that a subtelomeric gene position effect is associated with the selective occurrence of RNAi-mediated silencing of silent surface protein genes, suggesting small interfering RNA (siRNA)-mediated epigenetic cross talks between silent and active surface antigen genes. Our integrated genomic and molecular approach discloses the correlation between gene position effects and siRNA-mediated trans-silencing, thus providing two new parameters for regulation of mutually exclusive gene expression and the genomic organization of variant gene families.
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Affiliation(s)
| | - Timo Oppermann
- Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | | | - John Cullum
- Department for Genetics, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Helmut Schmidt
- Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Martin Simon
- Saarland University, Centre for Human and Molecular Biology, Molecular Cellular Dynamics, Saarbrücken, Germany
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8
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Dalmasso MC, Carmona SJ, Angel SO, Agüero F. Characterization of Toxoplasma gondii subtelomeric-like regions: identification of a long-range compositional bias that is also associated with gene-poor regions. BMC Genomics 2014; 15:21. [PMID: 24417889 PMCID: PMC4008256 DOI: 10.1186/1471-2164-15-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 01/02/2014] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Chromosome ends are composed of telomeric repeats and subtelomeric regions, which are patchworks of genes interspersed with repeated elements. Although chromosome ends display similar arrangements in different species, their sequences are highly divergent. In addition, these regions display a particular nucleosomal composition and bind specific factors, therefore producing a special kind of heterochromatin. Using data from currently available draft genomes we have characterized these putative Telomeric Associated Sequences in Toxoplasma gondii. RESULTS An all-vs-all pairwise comparison of T. gondii assembled chromosomes revealed the presence of conserved regions of ∼ 30 Kb located near the ends of 9 of the 14 chromosomes of the genome of the ME49 strain. Sequence similarity among these regions is ∼ 70%, and they are also highly conserved in the GT1 and VEG strains. However, they are unique to Toxoplasma with no detectable similarity in other Apicomplexan parasites. The internal structure of these sequences consists of 3 repetitive regions separated by high-complexity sequences without annotated genes, except for a gene from the Toxoplasma Specific Family. ChIP-qPCR experiments showed that nucleosomes associated to these sequences are enriched in histone H4 monomethylated at K20 (H4K20me1), and the histone variant H2A.X, suggesting that they are silenced sequences (heterochromatin). A detailed characterization of the base composition of these sequences, led us to identify a strong long-range compositional bias, which was similar to that observed in other genomic silenced fragments such as those containing centromeric sequences, and was negatively correlated to gene density. CONCLUSIONS We identified and characterized a region present in most Toxoplasma assembled chromosomes. Based on their location, sequence features, and nucleosomal markers we propose that these might be part of subtelomeric regions of T. gondii. The identified regions display a unique trinucleotide compositional bias, which is shared (despite the lack of any detectable sequence similarity) with other silenced sequences, such as those making up the chromosome centromeres. We also identified other genomic regions with this compositional bias (but no detectable sequence similarity) that might be functionally similar.
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Affiliation(s)
| | | | - Sergio O Angel
- Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús, UNSAM - CONICET, Sede Chascomús, Av, Intendente Marino Km 8, 2 CC 164, B 7130 IWA, Chascomús, Argentina.
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9
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Russell K, Hasenkamp S, Emes R, Horrocks P. Analysis of the spatial and temporal arrangement of transcripts over intergenic regions in the human malarial parasite Plasmodium falciparum. BMC Genomics 2013; 14:267. [PMID: 23601558 PMCID: PMC3681616 DOI: 10.1186/1471-2164-14-267] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/06/2013] [Indexed: 11/25/2022] Open
Abstract
Background The ability of the human malarial parasite Plasmodium falciparum to invade, colonise and multiply within diverse host environments, as well as to manifest its virulence within the human host, are activities tightly linked to the temporal and spatial control of gene expression. Yet, despite the wealth of high throughput transcriptomic data available for this organism there is very little information regarding the location of key transcriptional landmarks or their associated cis-acting regulatory elements. Here we provide a systematic exploration of the size and organisation of transcripts within intergenic regions to yield surrogate information regarding transcriptional landmarks, and to also explore the spatial and temporal organisation of transcripts over these poorly characterised genomic regions. Results Utilising the transcript data for a cohort of 105 genes we demonstrate that the untranscribed regions of mRNA are large and apportioned predominantly to the 5′ end of the open reading frame. Given the relatively compact size of the P. falciparum genome, we suggest that whilst transcriptional units are likely to spatially overlap, temporal co-transcription of adjacent transcriptional units is actually limited. Critically, the size of intergenic regions is directly dependent on the orientation of the two transcriptional units arrayed over them, an observation we extend to an analysis of the complete sequences of twelve additional organisms that share moderately compact genomes. Conclusions Our study provides a theoretical framework that extends our current understanding of the transcriptional landscape across the P. falciparum genome. Demonstration of a consensus gene-spacing rule that is shared between P. falciparum and ten other moderately compact genomes of apicomplexan parasites reveals the potential for our findings to have a wider impact across a phylum that contains many organisms important to human and veterinary health.
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Affiliation(s)
- Karen Russell
- Institute for Science and Technology in Medicine, Keele University, Huxley Building, Staffordshire ST5 5BG, United Kingdom
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10
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Abstract
Temporal and spatial organization of the nucleus is critical for the control of transcription, mRNA processing and the assembly of ribosomes. This includes the occupancy of specific territories by mammalian chromosomes, the presence of subnuclear compartments such as the nucleolus and Cajal bodies and the division of chromatin between active and inactive states. These latter are commonly associated with the location of DNA within euchromatin and heterochromatin respectively; critically these distinctions arise through modifications to chromatin-associated proteins, including histones, as well as the preferential localization of heterochromatin at the nuclear periphery. Most research on nuclear organization has focused on metazoa and fungi; however, recent technical advances have made more divergent eukaryotes accessible to study, with some surprising results. For example, the organization of heterochromatin is mediated in metazoan nuclei in large part by lamins, the prototypical intermediate filament proteins. Despite the presence of heterochromatin, detected both biochemically and by EM in most eukaryotic organisms, until this year lamins were thought to be restricted to metazoan taxa, and the proteins comprising the lamina in other lineages were unknown. Recent work indicates the presence of lamin orthologs in amoeba, while trypanosomatids possess a large coiled-coil protein, NUP-1, that performs functions analogous to lamins. These data indicate that the presence of a nuclear lamina is substantially more widespread than previously thought, with major implications for the evolution of eukaryotic gene expression mechanisms. We discuss these and other recent findings on the organization of nuclei in diverse organisms, and the implications of these findings for the evolutionary origin of eukaryotes.
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Affiliation(s)
- Mark C Field
- Department of Pathology; University of Cambridge, Cambridge, UK.
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11
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Religa AA, Waters AP. Sirtuins of parasitic protozoa: in search of function(s). Mol Biochem Parasitol 2012; 185:71-88. [PMID: 22906508 PMCID: PMC3484402 DOI: 10.1016/j.molbiopara.2012.08.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/01/2012] [Accepted: 08/02/2012] [Indexed: 01/09/2023]
Abstract
The SIR2 family of NAD+-dependent protein deacetylases, collectively called sirtuins, has been of central interest due to their proposed roles in life-span regulation and ageing. Sirtuins are one group of environment sensors of a cell interpreting external information and orchestrating internal responses at the sub-cellular level, through participation in gene regulation mechanisms. Remarkably conserved across all kingdoms of life SIR2 proteins in several protozoan parasites appear to have both conserved and intriguing unique functions. This review summarises our current knowledge of the members of the sirtuin families in Apicomplexa, including Plasmodium, and other protozoan parasites such as Trypanosoma and Leishmania. The wide diversity of processes regulated by SIR2 proteins makes them targets worthy of exploitation in anti-parasitic therapies.
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Affiliation(s)
- Agnieszka A Religa
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, UK.
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12
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Abstract
Gene manipulation is an invaluable tool to investigate and understand the biology of an organism. Although this technology has been applied to both the human and rodent malarial parasites (RMP), Plasmodium berghei in particular offers a more robust system due to a higher and more efficient transformation rate. Here, we describe a comprehensive transfection and selection protocol using P. berghei including a variant negative selection protocol administering 5-fluorocytosine to the animals in drinking water. Additionally, we discuss and assess the latest advances in gene manipulation technologies developed in RMP to gain a better understanding of Plasmodium biology.
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13
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Expression of P. falciparum var genes involves exchange of the histone variant H2A.Z at the promoter. PLoS Pathog 2011; 7:e1001292. [PMID: 21379342 PMCID: PMC3040674 DOI: 10.1371/journal.ppat.1001292] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 01/12/2011] [Indexed: 12/31/2022] Open
Abstract
Plasmodium falciparum employs antigenic variation to evade the human immune response by switching the expression of different variant surface antigens encoded by the var gene family. Epigenetic mechanisms including histone modifications and sub-nuclear compartmentalization contribute to transcriptional regulation in the malaria parasite, in particular to control antigenic variation. Another mechanism of epigenetic control is the exchange of canonical histones with alternative variants to generate functionally specialized chromatin domains. Here we demonstrate that the alternative histone PfH2A.Z is associated with the epigenetic regulation of var genes. In many eukaryotic organisms the histone variant H2A.Z mediates an open chromatin structure at promoters and facilitates diverse levels of regulation, including transcriptional activation. Throughout the asexual, intraerythrocytic lifecycle of P. falciparum we found that the P. falciparum ortholog of H2A.Z (PfH2A.Z) colocalizes with histone modifications that are characteristic of transcriptionally-permissive euchromatin, but not with markers of heterochromatin. Consistent with this finding, antibodies to PfH2A.Z co-precipitate the permissive modification H3K4me3. By chromatin-immunoprecipitation we show that PfH2A.Z is enriched in nucleosomes around the transcription start site (TSS) in both transcriptionally active and silent stage-specific genes. In var genes, however, PfH2A.Z is enriched at the TSS only during active transcription in ring stage parasites. Thus, in contrast to other genes, temporal var gene regulation involves histone variant exchange at promoter nucleosomes. Sir2 histone deacetylases are important for var gene silencing and their yeast ortholog antagonises H2A.Z function in subtelomeric yeast genes. In immature P. falciparum parasites lacking Sir2A or Sir2B high var transcription levels correlate with enrichment of PfH2A.Z at the TSS. As Sir2A knock out parasites mature the var genes are silenced, but PfH2A.Z remains enriched at the TSS of var genes; in contrast, PfH2A.Z is lost from the TSS of de-repressed var genes in mature Sir2B knock out parasites. This result indicates that PfH2A.Z occupancy at the active var promoter is antagonized by PfSir2A during the intraerythrocytic life cycle. We conclude that PfH2A.Z contributes to the nucleosome architecture at promoters and is regulated dynamically in active var genes. Plasmodium falciparum is a protist parasite that causes malaria and kills more than 800,000 people per year. The parasite escapes from the human immune response by antigenic variation through switching between expression of different var genes. These encode different variant antigens that are expressed on the surface of the infected erythrocyte and mediate pathogenic adhesion of the infected erythrocytes to host receptors. Understanding how this process is regulated may lead to the identification of factors that are essential for immune evasion and that could represent novel drug targets. Here, we have identified the parasite's histone variant PfH2A.Z as a novel contributor to the transcriptional regulation of antigenic variation. PfH2A.Z is enriched in the promoter of many genes, but enrichment correlates with gene expression only in var genes. Furthermore we show that PfH2A.Z enrichment in var promoters is antagonised by the var gene silencing factor PfSir2A. These findings further extend our knowledge of the complex mechanisms regulating gene expression in P. falciparum.
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