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The nuclear envelope and gene organization in parasitic protozoa: Specializations associated with disease. Mol Biochem Parasitol 2016; 209:104-113. [PMID: 27475118 DOI: 10.1016/j.molbiopara.2016.07.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/12/2016] [Accepted: 07/26/2016] [Indexed: 12/11/2022]
Abstract
The parasitic protozoa Trypanosoma brucei and Plasmodium falciparum are lethal human parasites that have developed elegant strategies of immune evasion by antigenic variation. Despite the vast evolutionary distance between the two taxa, both parasites employ strict monoallelic expression of their membrane proteins, variant surface glycoproteins in Trypanosomes and the var, rif and stevor genes in Plasmodium, in order to evade their host's immune system. Additionally, both telomeric location and epigenetic controls are prominent features of these membrane proteins. As such, telomeres, chromatin structure and nuclear organization all contribute to control of gene expression and immune evasion. Here, we discuss the importance of epigenetics and sub-nuclear context for the survival of these disease-causing parasites.
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Stanojcic S, Sollelis L, Kuk N, Crobu L, Balard Y, Schwob E, Bastien P, Pagès M, Sterkers Y. Single-molecule analysis of DNA replication reveals novel features in the divergent eukaryotes Leishmania and Trypanosoma brucei versus mammalian cells. Sci Rep 2016; 6:23142. [PMID: 26976742 PMCID: PMC4791591 DOI: 10.1038/srep23142] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 02/17/2016] [Indexed: 01/29/2023] Open
Abstract
Leishmania and Trypanosoma are unicellular parasites that possess markedly original biological features as compared to other eukaryotes. The Leishmania genome displays a constitutive 'mosaic aneuploidy', whereas in Trypanosoma brucei, the megabase-sized chromosomes are diploid. We accurately analysed DNA replication parameters in three Leishmania species and Trypanosoma brucei as well as mouse embryonic fibroblasts (MEF). Active replication origins were visualized at the single molecule level using DNA molecular combing. More than one active origin was found on most DNA fibres, showing that the chromosomes are replicated from multiple origins. Inter-origin distances (IODs) were measured and found very large in trypanosomatids: the mean IOD was 160 kb in T. brucei and 226 kb in L. mexicana. Moreover, the progression of replication forks was faster than in any other eukaryote analyzed so far (mean velocity 1.9 kb/min in T. brucei and 2.4-2.6 kb/min in Leishmania). The estimated total number of active DNA replication origins in trypanosomatids is ~170. Finally, 14.4% of unidirectional replication forks were observed in T. brucei, in contrast to 1.5-1.7% in Leishmania and 4% in MEF cells. The biological significance of these original features is discussed.
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Affiliation(s)
- Slavica Stanojcic
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France
| | - Lauriane Sollelis
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France
| | - Nada Kuk
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France
| | - Lucien Crobu
- CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France
| | - Yves Balard
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France
| | - Etienne Schwob
- Institute of Molecular Genetics, CNRS UMR5535 &University of Montpellier, Montpellier, F34293, France
| | - Patrick Bastien
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.,CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.,University Hospital Centre (CHU), Department of Parasitology-Mycology, Montpellier, F34090, France
| | - Michel Pagès
- CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France
| | - Yvon Sterkers
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.,CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.,University Hospital Centre (CHU), Department of Parasitology-Mycology, Montpellier, F34090, France
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3
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Dejung M, Subota I, Bucerius F, Dindar G, Freiwald A, Engstler M, Boshart M, Butter F, Janzen CJ. Quantitative Proteomics Uncovers Novel Factors Involved in Developmental Differentiation of Trypanosoma brucei. PLoS Pathog 2016; 12:e1005439. [PMID: 26910529 PMCID: PMC4765897 DOI: 10.1371/journal.ppat.1005439] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 01/15/2016] [Indexed: 11/18/2022] Open
Abstract
Developmental differentiation is a universal biological process that allows cells to adapt to different environments to perform specific functions. African trypanosomes progress through a tightly regulated life cycle in order to survive in different host environments when they shuttle between an insect vector and a vertebrate host. Transcriptomics has been useful to gain insight into RNA changes during stage transitions; however, RNA levels are only a moderate proxy for protein abundance in trypanosomes. We quantified 4270 protein groups during stage differentiation from the mammalian-infective to the insect form and provide classification for their expression profiles during development. Our label-free quantitative proteomics study revealed previously unknown components of the differentiation machinery that are involved in essential biological processes such as signaling, posttranslational protein modifications, trafficking and nuclear transport. Furthermore, guided by our proteomic survey, we identified the cause of the previously observed differentiation impairment in the histone methyltransferase DOT1B knock-out strain as it is required for accurate karyokinesis in the first cell division during differentiation. This epigenetic regulator is likely involved in essential chromatin restructuring during developmental differentiation, which might also be important for differentiation in higher eukaryotic cells. Our proteome dataset will serve as a resource for detailed investigations of cell differentiation to shed more light on the molecular mechanisms of this process in trypanosomes and other eukaryotes.
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Affiliation(s)
- Mario Dejung
- Institute of Molecular Biology (IMB), Ackermannweg 4, Mainz, Germany
| | - Ines Subota
- Department of Cell and Developmental Biology, Biocenter, University Wuerzburg, Am Hubland, Wuerzburg, Germany
| | - Ferdinand Bucerius
- Department Biology I, Genetics, University of Munich (LMU), Großhaderner, Martinsried, Germany
| | - Gülcin Dindar
- Department of Cell and Developmental Biology, Biocenter, University Wuerzburg, Am Hubland, Wuerzburg, Germany
| | - Anja Freiwald
- Institute of Molecular Biology (IMB), Ackermannweg 4, Mainz, Germany
| | - Markus Engstler
- Department of Cell and Developmental Biology, Biocenter, University Wuerzburg, Am Hubland, Wuerzburg, Germany
| | - Michael Boshart
- Department Biology I, Genetics, University of Munich (LMU), Großhaderner, Martinsried, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, Mainz, Germany
- * E-mail: (FB); (CJJ)
| | - Christian J. Janzen
- Department of Cell and Developmental Biology, Biocenter, University Wuerzburg, Am Hubland, Wuerzburg, Germany
- * E-mail: (FB); (CJJ)
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4
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Pena AC, Pimentel MR, Manso H, Vaz-Drago R, Pinto-Neves D, Aresta-Branco F, Rijo-Ferreira F, Guegan F, Pedro Coelho L, Carmo-Fonseca M, Barbosa-Morais NL, Figueiredo LM. Trypanosoma brucei histone H1 inhibits RNA polymerase I transcription and is important for parasite fitness in vivo. Mol Microbiol 2014; 93:645-63. [PMID: 24946224 PMCID: PMC4285223 DOI: 10.1111/mmi.12677] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2014] [Indexed: 11/30/2022]
Abstract
Trypanosoma brucei is a unicellular parasite that causes sleeping sickness in humans. Most of its transcription is constitutive and driven by RNA polymerase II. RNA polymerase I (Pol I) transcribes not only ribosomal RNA genes, but also protein-encoding genes, including variant surface glycoproteins (VSGs) and procyclins. In T. brucei, histone H1 (H1) is required for VSG silencing and chromatin condensation. However, whether H1 has a genome-wide role in transcription is unknown. Here, using RNA sequencing we show that H1 depletion changes the expression of a specific cohort of genes. Interestingly, the predominant effect is partial loss of silencing of Pol I loci, such as VSG and procyclin genes. Labelling of nascent transcripts with 4-thiouridine showed that H1 depletion does not alter the level of labelled Pol II transcripts. In contrast, the levels of 4sU-labelled Pol I transcripts were increased by two- to sixfold, suggesting that H1 preferentially blocks transcription at Pol I loci. Finally, we observed that parasites depleted of H1 grow almost normally in culture but they have a reduced fitness in mice, suggesting that H1 is important for host-pathogen interactions.
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Affiliation(s)
- Ana C Pena
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Edifício Egas Moniz, 1649-028, Lisboa, Portugal
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5
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Changes in cyst's nuclear chromatin resulting after experimental manipulation of Taenia crassiceps mice infections: biological implications. Exp Parasitol 2012; 130:423-9. [PMID: 22343043 DOI: 10.1016/j.exppara.2012.01.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 01/20/2012] [Accepted: 01/25/2012] [Indexed: 11/23/2022]
Abstract
During some estimations of the nuclear DNA content, based on determinations propidium iodide (PI) binding through fluorocytometry for Taenia crassiceps cysticerci, significant variation in the results were found. This initial observation led to a series of experiments designed to explain the variation. These changes could be induced by the diameter of the needles in the syringes used for the mouse to mouse transfer of the cysts. Nuclei from cysts transferred through 27-gauge needles showed 30% less PI staining than those transferred through 21 gauge needles, after 2 months infections. Reduction in PI capture induced by 27-gauge needle was reversible when the cysts were maintained in their mice hosts during 5 months. Moreover, variation in PI binding to cysticercal DNA was also found when comparing parasites grown in male versus female mice. The use of agents that homogenize the chromatin structure during PI staining, allowed demonstrating that variation were entirely due to differences in the chromatin relaxation/compaction. Additional experiments demonstrated that the higher compaction is accompanied by a reduced ability of cysts to grow in the peritoneal cavity of BALB/cAnN mice. Furthermore, proteomic analysis also showed that these changes in chromatin relaxation/compaction resulted in different levels and patterns of protein expression. Our results strongly suggest that chromatin is involved in several well characterized phenomena of the T. crassiceps murine model, and open new avenues for a detailed approach to understand such a complex host-parasite relationship.
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6
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Kramer S. Developmental regulation of gene expression in the absence of transcriptional control: The case of kinetoplastids. Mol Biochem Parasitol 2012; 181:61-72. [PMID: 22019385 DOI: 10.1016/j.molbiopara.2011.10.002] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 10/03/2011] [Accepted: 10/04/2011] [Indexed: 11/25/2022]
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7
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Ersfeld K. Nuclear architecture, genome and chromatin organisation in Trypanosoma brucei. Res Microbiol 2011; 162:626-36. [PMID: 21392575 DOI: 10.1016/j.resmic.2011.01.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 01/29/2011] [Indexed: 11/29/2022]
Abstract
The nucleus of the human pathogen Trypanosoma brucei not only has unusual chromosomal composition, characterised by the presence of megabase, intermediate and minichromosomes, but also chromosome and gene organisation that is unique amongst eukaryotes. Here I provide an overview of current knowledge of nuclear structure, chromatin organisation and chromosome dynamics during interphase and mitosis. New technologies such as chromatin immunoprecipitation, in combination with new generation sequencing and proteomic analysis of subnuclear fractions, have led to novel insights into the organisation of the nucleus and chromatin. In particular, we are beginning to understand how universal mechanisms of chromatin modifications and nuclear position effects are deployed for parasite-specific functions and are centrally involved in genomic organisation and transcriptional regulation. These advances also have a major impact on progress in understanding the molecular basis of antigenic variation.
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Affiliation(s)
- Klaus Ersfeld
- Department of Biological Sciences and Hull York Medical School, University of Hull, Hull HU6 7RX, UK.
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8
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Eirín-López JM, Ausió J. Origin and evolution of chromosomal sperm proteins. Bioessays 2009; 31:1062-70. [PMID: 19708021 DOI: 10.1002/bies.200900050] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the eukaryotic cell, DNA compaction is achieved through its interaction with histones, constituting a nucleoprotein complex called chromatin. During metazoan evolution, the different structural and functional constraints imposed on the somatic and germinal cell lines led to a unique process of specialization of the sperm nuclear basic proteins (SNBPs) associated with chromatin in male germ cells. SNBPs encompass a heterogeneous group of proteins which, since their discovery in the nineteenth century, have been studied extensively in different organisms. However, the origin and controversial mechanisms driving the evolution of this group of proteins has only recently started to be understood. Here, we analyze in detail the histone hypothesis for the vertical parallel evolution of SNBPs, involving a "vertical" transition from a histone to a protamine-like and finally protamine types (H --> PL --> P), the last one of which is present in the sperm of organisms at the uppermost tips of the phylogenetic tree. In particular, the common ancestry shared by the protamine-like (PL)- and protamine (P)-types with histone H1 is discussed within the context of the diverse structural and functional constraints acting upon these proteins during bilaterian evolution.
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Affiliation(s)
- José M Eirín-López
- Departamento de Biología Celular y Molecular, Universidade da Coruña, Coruña, Spain
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9
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Abstract
Epigenetic regulation is important in many facets of eukaryotic biology. Recent work has suggested that the basic mechanisms underlying epigenetic regulation extend to eukaryotic parasites. The identification of post-translational histone modifications and chromatin-modifying enzymes is beginning to reveal both common and novel functions for chromatin in these parasites. In this Review, we compare the role of epigenetics in African trypanosomes and humans in several biological processes. We discuss how the study of trypanosome chromatin might help us to better understand the evolution of epigenetic processes.
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García-Salcedo JA, Gijón P, Nolan DP, Tebabi P, Pays E. A chromosomal SIR2 homologue with both histone NAD-dependent ADP-ribosyltransferase and deacetylase activities is involved in DNA repair in Trypanosoma brucei. EMBO J 2003; 22:5851-62. [PMID: 14592982 PMCID: PMC275410 DOI: 10.1093/emboj/cdg553] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
SIR2-like proteins have been implicated in a wide range of cellular events including chromosome silencing, chromosome segregation, DNA recombination and the determination of life span. We report here the molecular and functional characterization of a SIR2-related protein from the protozoan parasite Trypanosoma brucei, which we termed TbSIR2RP1. This protein is a chromosome-associated NAD-dependent enzyme which, in contrast to other known proteins of this family, catalyses both ADP-ribosylation and deacetylation of histones, particulary H2A and H2B. Under- or overexpression of TbSIR2RP1 decreased or increased, respectively, cellular resistance to DNA damage. Treatment of trypanosomal nuclei with a DNA alkylating agent resulted in a significant increase in the level of histone ADP-ribosylation and a concomitant increase in chromatin sensitivity to micrococcal nuclease. Both of these responses correlated with the level of TbSIR2RP1 expression. We propose that histone modification by TbSIR2RP1 is involved in DNA repair.
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Affiliation(s)
- José A García-Salcedo
- Institute of Molecular Biology and Medicine, Free University of Brussels, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
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11
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Doerig C, Chakrabarti D, Kappes B, Matthews K. The cell cycle in protozoan parasites. PROGRESS IN CELL CYCLE RESEARCH 2000; 4:163-83. [PMID: 10740824 DOI: 10.1007/978-1-4615-4253-7_15] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Research into cell cycle control in protozoan parasites, which are responsible for major public health problems in the developing world, has been hampered by the difficulties in performing classical genetic analysis with these organisms. Nevertheless, in a large part thanks to the data gathered in other eukaryotic systems and to the acquisition of the sequences of parasite genes homologous to cell cycle regulators, many molecular tools required for an in-depth study of the cell cycle in protozoan parasites have been collected over the past few years. Despite the considerable phylogenetic divergence between these organisms and other eukaryotes, and notwithstanding important specificities such as the apparent lack of checkpoints during cell cycle progression, available data indicate that the major families of cell cycle regulators appear to operate in protozoan parasites. Functional studies are now needed to define the precise role of these regulators in the life cycle of the parasites, and to possibly validate cell cycle control elements as potential targets for chemotherapy.
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Affiliation(s)
- C Doerig
- INSERM U313, Immunobiologie moléculaire et cellulaire des maladies parasitaires, Paris, France
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12
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Abstract
The mechanisms which control the expression of developmentally regulated genes in trypanosomatids remain unclear. The genes are grouped together into transcription units that are co-transcribed to yield polycistronic RNAs. Trans-splicing and polyadenylation give rise to mature, monocistronic mRNAs. It is difficult to imagine that expression of these genes is controlled at the level of transcription initiation because this would suggest that the genes are transcribed at the same rate. This is not the case, because at any given developmental stage in trypanosomes or Leishmania, genes transcribed from the same transcription unit are expressed at different levels within the cell. Consequently, these parasites must rely on post-transcriptional or post-translational mechanisms to generate the appropriate levels of gene product within the cell. There are no well-established examples of RNA polymerase II promoters in trypanosomes or Leishmania. However, the promoters for genes encoding the variant surface glycoprotein (VSG) and the procyclic acidic repetitive protein (PARP) have been identified and resemble ribosomal RNA polymerase I promoters. In higher eukaryotes where the mechanisms regulating transcription are clearer, there is increasing evidence that epigenetic factors, such as histones and modified bases, influence gene expression. Chemical modification of these factors can restructure chromatin and lead to gene activation or silencing. In trypanosomatids, an epigenetic mechanism for the control of developmentally expressed genes is a possibility. In this review, chromatin remodelling during the life and cell cycle of trypanosomes and Leishmania is explored, and the influence of epigenetic factors such as histones and modified bases on this process is discussed.
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Affiliation(s)
- S I Belli
- Molecular Parasitology Unit, Department of Cell and Molecular Biology, University of Technology, Sydney, Westbourne Street, Gore Hill, NSW 2065, Australia.
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Soto M, Quijada L, Alonso C, Requena JM. Molecular cloning and analysis of expression of the Leishmania infantum histone H4 genes. Mol Biochem Parasitol 1997; 90:439-47. [PMID: 9476792 DOI: 10.1016/s0166-6851(97)00178-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the present work, we describe the sequence, organization and expression of histone H4 genes in the protozoan parasite Leishmania infantum. The predicted L. infantum histone H4 is a polypeptide of 100 amino acids with a molecular mass of 11.5 kDa. Comparison of the amino acid sequence of Leishmania histone H4 with the rest of histone H4 sequences indicates that this is the most divergent sequence reported to date. The genomic distribution analysis of histone H4 genes indicates that there must be up to seven gene copies. A single size-class histone H4 mRNA of 0.6 kb was detected, whose level dramatically decreases from logarithmic to stationary phase. However, the Leishmania histone H4 mRNAs do not decrease in abundance following treatment with inhibitors of DNA synthesis, suggesting a regulation by a replication-independent mechanism.
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Affiliation(s)
- M Soto
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Spain
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Reverol L, Chirinos M, Henriquez DA. Presence of an unusually high concentration of an ubiquitinated histone-like protein in Trypanosoma cruzi. J Cell Biochem 1997; 66:433-40. [PMID: 9282321 DOI: 10.1002/(sici)1097-4644(19970915)66:4<433::aid-jcb2>3.0.co;2-m] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The conjugation of ubiquitin to histones H2A and H2B has been established in higher eukaryotes and has been related to changes in chromatin organization. In Trypanosoma cruzi, no condensation of chromatin occurs during mitosis. In order to determine the presence of histone ubiquitination in T. cruzi epimastigotes, histones were extracted from chromatin and analyzed by three electrophoretic systems: acid-urea, triton-acid-urea and sodium-dodecyl-sulphate polyacrylamide gel. The immunochemical detection of ubiquitin-histone conjugates by Western blotting showed a strong reaction with a slow migrating band of M(r) 19 kDa. The high percentage of ubiquitin-histone conjugates present in T. cruzi chromatin may be related to the inability of this parasite to condense chromatin into a 30 nm fiber.
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Affiliation(s)
- L Reverol
- Department of Cell Biology, Universidad Simón Bolívar, Caracas, Venezuela
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