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Ashraf K, Nabeel-Shah S, Garg J, Saettone A, Derynck J, Gingras AC, Lambert JP, Pearlman RE, Fillingham J. Proteomic Analysis of Histones H2A/H2B and Variant Hv1 in Tetrahymena thermophila Reveals an Ancient Network of Chaperones. Mol Biol Evol 2019; 36:1037-1055. [PMID: 30796450 PMCID: PMC6502085 DOI: 10.1093/molbev/msz039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Epigenetic information, which can be passed on independently of the DNA sequence, is stored in part in the form of histone posttranslational modifications and specific histone variants. Although complexes necessary for deposition have been identified for canonical and variant histones, information regarding the chromatin assembly pathways outside of the Opisthokonts remains limited. Tetrahymena thermophila, a ciliated protozoan, is particularly suitable to study and unravel the chromatin regulatory layers due to its unique physical separation of chromatin states in the form of two distinct nuclei present within the same cell. Using a functional proteomics pipeline, we carried out affinity purification followed by mass spectrometry of endogenously tagged T. thermophila histones H2A, H2B and variant Hv1.We identified a set of interacting proteins shared among the three analyzed histones that includes the FACT-complex, as well as H2A- or Hv1-specific chaperones. We find that putative subunits of T. thermophila versions of SWR- and INO80-complexes, as well as transcription-related histone chaperone Spt6Tt specifically copurify with Hv1. We also identified importin β6 and the T. thermophila ortholog of nucleoplasmin 1 (cNpl1Tt) as H2A–H2B interacting partners. Our results further implicate Poly [ADP-ribose] polymerases in histone metabolism. Molecular evolutionary analysis, reciprocal affinity purification coupled to mass spectrometry experiments, and indirect immunofluorescence studies using endogenously tagged Spt16Tt (FACT-complex subunit), cNpl1Tt, and PARP6Tt underscore the validity of our approach and offer mechanistic insights. Our results reveal a highly conserved regulatory network for H2A (Hv1)–H2B concerning their nuclear import and assembly into chromatin.
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Affiliation(s)
- Kanwal Ashraf
- Department of Biology, York University, Toronto, ON, Canada
| | - Syed Nabeel-Shah
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada.,Donnelly Centre, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jyoti Garg
- Department of Biology, York University, Toronto, ON, Canada
| | - Alejandro Saettone
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Joanna Derynck
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Anne-Claude Gingras
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Jean-Philippe Lambert
- Department of Molecular Medicine and Cancer Research Centre, Université Laval, Québec, QC, Canada.,CHU de Québec Research Center, CHUL, Québec, QC, Canada
| | | | - Jeffrey Fillingham
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
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Saettone A, Nabeel-Shah S, Garg J, Lambert JP, Pearlman RE, Fillingham J. Functional Proteomics of Nuclear Proteins in Tetrahymena thermophila: A Review. Genes (Basel) 2019; 10:E333. [PMID: 31052454 PMCID: PMC6562869 DOI: 10.3390/genes10050333] [Citation(s) in RCA: 8] [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: 03/27/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 12/14/2022] Open
Abstract
Identification and characterization of protein complexes and interactomes has been essential to the understanding of fundamental nuclear processes including transcription, replication, recombination, and maintenance of genome stability. Despite significant progress in elucidation of nuclear proteomes and interactomes of organisms such as yeast and mammalian systems, progress in other models has lagged. Protists, including the alveolate ciliate protozoa with Tetrahymena thermophila as one of the most studied members of this group, have a unique nuclear biology, and nuclear dimorphism, with structurally and functionally distinct nuclei in a common cytoplasm. These features have been important in providing important insights about numerous fundamental nuclear processes. Here, we review the proteomic approaches that were historically used as well as those currently employed to take advantage of the unique biology of the ciliates, focusing on Tetrahymena, to address important questions and better understand nuclear processes including chromatin biology of eukaryotes.
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Affiliation(s)
- Alejandro Saettone
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada.
| | - Syed Nabeel-Shah
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
| | - Jyoti Garg
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
| | - Jean-Philippe Lambert
- Department of Molecular Medicine and Cancer Research Centre, Université Laval, Quebec, QC, G1V 0A6, Canada.
- CHU de Québec Research Center, CHUL, 2705 Boulevard Laurier, Quebec, QC, G1V 4G2, Canada
| | - Ronald E Pearlman
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
| | - Jeffrey Fillingham
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada.
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Kaczanowski A, Kiersnowska M. Formation and degradation of large extrusion bodies in Tetrahymena thermophila: The role of intramacronuclear microtubules in chromatin segregation. Eur J Protistol 2018; 66:177-188. [DOI: 10.1016/j.ejop.2018.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 11/17/2022]
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Endo M, Sugai T. Amitotic division of the macronucleus in Tetrahymena thermophila: DNA distribution by genomic unit. Zoolog Sci 2011; 28:482-90. [PMID: 21728796 DOI: 10.2108/zsj.28.482] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The macronucleus of the ciliate Tetrahymena cell contains euchromatin and numerous heterochromatins called chromatin bodies. During cell division, a chromatin aggregate larger than chromatin body appears in the macronucleus. We observed chromatin aggregates in the dividing macronucleus in a living T. thermophila cell, and found that these were globular in morphology and homogeneous in size. To observe globular chromatin clearly, optimal conditions for making it compact were studied. Addition of Mg ion, benomyl and oryzalin, microtubule inhibitors, to cell suspension was effective. Globular chromatin appeared when the micronuclear anaphase began at the cell cortex, and disappeared long after cell separation. Using living cells with a small macronucleus at early log phase, we counted the number of globular chromatin per nucleus and measured the DNA content of globular chromatin in the macronucleus which was stained with Hoechst 33342 by using ImageJ. The number of globular chromatin per nucleus was reduced by half after division, indicating the globular chromatin is a distribution unit of DNA. A globular chromatin contained similar DNA content as that of the macronuclear genome. We developed methods for inducing and isolating a cell with an extremely small macronucleus with a DNA amount of one globular chromatin. These cells grew, divided, and give clones, suggesting that the macronuclear genome is not dispersed within the macronucleus and the globular chromatin may be a macronuclear genome. We named this globular chromatin "macronuclear genome unit" (MGU).
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Affiliation(s)
- Masaki Endo
- Department of Biology, College of Science, lbaraki University, 2-1-1, Bunkyo, Mito 310-8512, Japan
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Libusová L, Sulimenko T, Sulimenko V, Janisch R, Hozák P, Dráber P. Distinct localization of a beta-tubulin epitope in the Tetrahymena thermophila and Paramecium caudatum cortex. PROTOPLASMA 2005; 225:157-67. [PMID: 16228897 DOI: 10.1007/s00709-005-0097-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Accepted: 12/17/2004] [Indexed: 05/04/2023]
Abstract
Many of the highly organized microtubular arrangements in ciliates are located in the cortical area containing membrane vesicles and vacuoles. In Tetrahymena thermophila and Paramecium caudatum, immunofluorescence microscopy with the monoclonal antibody TU-06, directed against beta-tubulin, revealed distinct staining of this cortical region alone, while the cilia and other microtubular structures were unstained. The specificity of the antibody was confirmed by immunoblotting and by preabsorption of the antibody with purified tubulin. Double-label immunofluorescence with antibodies against gamma-tubulin, detyrosinated alpha-tubulin, and centrin showed that the TU-06 epitope is localized outside the basal body region. This was also confirmed by immunogold electron microscopy of thin sections. Proteolytic digestion of porcine brain beta-tubulin combined with a peptide scan of immobilized, overlapping peptides disclosed that the epitope was in the beta-tubulin region beta81-95, a region which is phylogenetically highly conserved. As known posttranslational modifications of beta-tubulin are located outside this area, the observed staining pattern cannot be interpreted as evidence of subcellular sequestration of modified tubulin. The limited distribution of the epitope could rather reflect the dependence of TU-06 epitope exposition on conformations of tubulin molecules in microtubule arrangements or on differential masking by interacting proteins.
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Affiliation(s)
- L Libusová
- Department of Biology of the Cytoskeleton, Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
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