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Doležalová A, Beránková D, Koláčková V, Hřibová E. Insight into chromatin compaction and spatial organization in rice interphase nuclei. FRONTIERS IN PLANT SCIENCE 2024; 15:1358760. [PMID: 38863533 PMCID: PMC11165205 DOI: 10.3389/fpls.2024.1358760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 05/13/2024] [Indexed: 06/13/2024]
Abstract
Chromatin organization and its interactions are essential for biological processes, such as DNA repair, transcription, and DNA replication. Detailed cytogenetics data on chromatin conformation, and the arrangement and mutual positioning of chromosome territories in interphase nuclei are still widely missing in plants. In this study, level of chromatin condensation in interphase nuclei of rice (Oryza sativa) and the distribution of chromosome territories (CTs) were analyzed. Super-resolution, stimulated emission depletion (STED) microscopy showed different levels of chromatin condensation in leaf and root interphase nuclei. 3D immuno-FISH experiments with painting probes specific to chromosomes 9 and 2 were conducted to investigate their spatial distribution in root and leaf nuclei. Six different configurations of chromosome territories, including their complete association, weak association, and complete separation, were observed in root meristematic nuclei, and four configurations were observed in leaf nuclei. The volume of CTs and frequency of their association varied between the tissue types. The frequency of association of CTs specific to chromosome 9, containing NOR region, is also affected by the activity of the 45S rDNA locus. Our data suggested that the arrangement of chromosomes in the nucleus is connected with the position and the size of the nucleolus.
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Affiliation(s)
| | | | | | - Eva Hřibová
- Institute of Experimental Botany of the Czech Academy of Science, Centre of Plants Structural and Functional Genomics, Olomouc, Czechia
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2
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Korsak S, Plewczynski D. LoopSage: An energy-based Monte Carlo approach for the loop extrusion modeling of chromatin. Methods 2024; 223:106-117. [PMID: 38295892 DOI: 10.1016/j.ymeth.2024.01.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/29/2023] [Accepted: 01/10/2024] [Indexed: 02/05/2024] Open
Abstract
The connection between the patterns observed in 3C-type experiments and the modeling of polymers remains unresolved. This paper presents a simulation pipeline that generates thermodynamic ensembles of 3D structures for topologically associated domain (TAD) regions by loop extrusion model (LEM). The simulations consist of two main components: a stochastic simulation phase, employing a Monte Carlo approach to simulate the binding positions of cohesins, and a dynamical simulation phase, utilizing these cohesins' positions to create 3D structures. In this approach, the system's total energy is the combined result of the Monte Carlo energy and the molecular simulation energy, which are iteratively updated. The structural maintenance of chromosomes (SMC) protein complexes are represented as loop extruders, while the CCCTC-binding factor (CTCF) locations on DNA sequence are modeled as energy minima on the Monte Carlo energy landscape. Finally, the spatial distances between DNA segments from ChIA-PET experiments are compared with the computer simulations, and we observe significant Pearson correlations between predictions and the real data. LoopSage model offers a fresh perspective on chromatin loop dynamics, allowing us to observe phase transition between sparse and condensed states in chromatin.
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Affiliation(s)
- Sevastianos Korsak
- Faculty of Mathematics and Information Science, Warsaw University of Technology, Warsaw, Poland; Center of New Technologies, University of Warsaw, Warsaw, Poland
| | - Dariusz Plewczynski
- Faculty of Mathematics and Information Science, Warsaw University of Technology, Warsaw, Poland; Center of New Technologies, University of Warsaw, Warsaw, Poland.
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3
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Caudai C, Salerno E. Complementing Hi-C information for 3D chromatin reconstruction by ChromStruct. FRONTIERS IN BIOINFORMATICS 2024; 3:1287168. [PMID: 38318534 PMCID: PMC10840501 DOI: 10.3389/fbinf.2023.1287168] [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: 09/01/2023] [Accepted: 12/20/2023] [Indexed: 02/07/2024] Open
Abstract
A multiscale method proposed elsewhere for reconstructing plausible 3D configurations of the chromatin in cell nuclei is recalled, based on the integration of contact data from Hi-C experiments and additional information coming from ChIP-seq, RNA-seq and ChIA-PET experiments. Provided that the additional data come from independent experiments, this kind of approach is supposed to leverage them to complement possibly noisy, biased or missing Hi-C records. When the different data sources are mutually concurrent, the resulting solutions are corroborated; otherwise, their validity would be weakened. Here, a problem of reliability arises, entailing an appropriate choice of the relative weights to be assigned to the different informational contributions. A series of experiments is presented that help to quantify the advantages and the limitations offered by this strategy. Whereas the advantages in accuracy are not always significant, the case of missing Hi-C data demonstrates the effectiveness of additional information in reconstructing the highly packed segments of the structure.
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Affiliation(s)
- Claudia Caudai
- Institute of Information Science and Technologies, National Research Council of Italy, Pisa, Italy
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4
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Chan B, Rubinstein M. Theory of chromatin organization maintained by active loop extrusion. Proc Natl Acad Sci U S A 2023; 120:e2222078120. [PMID: 37253009 PMCID: PMC10266055 DOI: 10.1073/pnas.2222078120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/13/2023] [Indexed: 06/01/2023] Open
Abstract
The active loop extrusion hypothesis proposes that chromatin threads through the cohesin protein complex into progressively larger loops until reaching specific boundary elements. We build upon this hypothesis and develop an analytical theory for active loop extrusion which predicts that loop formation probability is a nonmonotonic function of loop length and describes chromatin contact probabilities. We validate our model with Monte Carlo and hybrid Molecular Dynamics-Monte Carlo simulations and demonstrate that our theory recapitulates experimental chromatin conformation capture data. Our results support active loop extrusion as a mechanism for chromatin organization and provide an analytical description of chromatin organization that may be used to specifically modify chromatin contact probabilities.
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Affiliation(s)
- Brian Chan
- Department of Biomedical Engineering, Duke University, Durham, NC27708
| | - Michael Rubinstein
- Department of Biomedical Engineering, Duke University, Durham, NC27708
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC27708
- Department of Chemistry, Duke University, Durham, NC27708
- Department of Physics, Duke University, Durham, NC27708
- Institute for Chemical Reaction Design and Discovery (World Premier International Research Center Initiative-ICReDD), Hokkaido University, Sapporo001-0021, Japan
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5
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Korolev N, Zinchenko A, Soman A, Chen Q, Wong SY, Berezhnoy NV, Basak R, van der Maarel JRC, van Noort J, Nordenskiöld L. Reconstituted TAD-size chromatin fibers feature heterogeneous nucleosome clusters. Sci Rep 2022; 12:15558. [PMID: 36114220 PMCID: PMC9481575 DOI: 10.1038/s41598-022-19471-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/30/2022] [Indexed: 11/14/2022] Open
Abstract
Large topologically associated domains (TADs) contain irregularly spaced nucleosome clutches, and interactions between such clutches are thought to aid the compaction of these domains. Here, we reconstituted TAD-sized chromatin fibers containing hundreds of nucleosomes on native source human and lambda-phage DNA and compared their mechanical properties at the single-molecule level with shorter ‘601’ arrays with various nucleosome repeat lengths. Fluorescent imaging showed increased compaction upon saturation of the DNA with histones and increasing magnesium concentration. Nucleosome clusters and their structural fluctuations were visualized in confined nanochannels. Force spectroscopy revealed not only similar mechanical properties of the TAD-sized fibers as shorter fibers but also large rupture events, consistent with breaking the interactions between distant clutches of nucleosomes. Though the arrays of native human DNA, lambda-phage and ‘601’ DNA featured minor differences in reconstitution yield and nucleosome stability, the fibers’ global structural and mechanical properties were similar, including the interactions between nucleosome clutches. These single-molecule experiments quantify the mechanical forces that stabilize large TAD-sized chromatin domains consisting of disordered, dynamically interacting nucleosome clutches and their effect on the condensation of large chromatin domains.
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6
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Zhang M, Díaz-Celis C, Onoa B, Cañari-Chumpitaz C, Requejo KI, Liu J, Vien M, Nogales E, Ren G, Bustamante C. Molecular organization of the early stages of nucleosome phase separation visualized by cryo-electron tomography. Mol Cell 2022; 82:3000-3014.e9. [PMID: 35907400 DOI: 10.1016/j.molcel.2022.06.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 05/09/2022] [Accepted: 06/28/2022] [Indexed: 12/16/2022]
Abstract
It has been proposed that the intrinsic property of nucleosome arrays to undergo liquid-liquid phase separation (LLPS) in vitro is responsible for chromatin domain organization in vivo. However, understanding nucleosomal LLPS has been hindered by the challenge to characterize the structure of the resulting heterogeneous condensates. We used cryo-electron tomography and deep-learning-based 3D reconstruction/segmentation to determine the molecular organization of condensates at various stages of LLPS. We show that nucleosomal LLPS involves a two-step process: a spinodal decomposition process yielding irregular condensates, followed by their unfavorable conversion into more compact, spherical nuclei that grow into larger spherical aggregates through accretion of spinodal materials or by fusion with other spherical condensates. Histone H1 catalyzes more than 10-fold the spinodal-to-spherical conversion. We propose that this transition involves exposure of nucleosome hydrophobic surfaces causing modified inter-nucleosome interactions. These results suggest a physical mechanism by which chromatin may transition from interphase to metaphase structures.
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Affiliation(s)
- Meng Zhang
- Applied Science and Technology Graduate Group, University of California, Berkeley, CA, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - César Díaz-Celis
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Bibiana Onoa
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | | | - Katherinne I Requejo
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Michael Vien
- Department of Physics, University of California, Berkeley, CA, USA
| | - Eva Nogales
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA; Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Carlos Bustamante
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA; Department of Chemistry, University of California, Berkeley, CA, USA; Department of Physics, University of California, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA; Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Kavli Energy Nanoscience Institute, University of California, Berkeley, CA, USA.
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7
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Li Y, Agrawal V, Virk RKA, Roth E, Li WS, Eshein A, Frederick J, Huang K, Almassalha L, Bleher R, Carignano MA, Szleifer I, Dravid VP, Backman V. Analysis of three-dimensional chromatin packing domains by chromatin scanning transmission electron microscopy (ChromSTEM). Sci Rep 2022; 12:12198. [PMID: 35842472 PMCID: PMC9288481 DOI: 10.1038/s41598-022-16028-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/04/2022] [Indexed: 11/09/2022] Open
Abstract
Chromatin organization over multiple length scales plays a critical role in the regulation of transcription. Deciphering the interplay of these processes requires high-resolution, three-dimensional, quantitative imaging of chromatin structure in vitro. Herein, we introduce ChromSTEM, a method that utilizes high-angle annular dark-field imaging and tomography in scanning transmission electron microscopy combined with DNA-specific staining for electron microscopy. We utilized ChromSTEM for an in-depth quantification of 3D chromatin conformation with high spatial resolution and contrast, allowing for characterization of higher-order chromatin structure almost down to the level of the DNA base pair. Employing mass scaling analysis on ChromSTEM mass density tomograms, we observed that chromatin forms spatially well-defined higher-order domains, around 80 nm in radius. Within domains, chromatin exhibits a polymeric fractal-like behavior and a radially decreasing mass-density from the center to the periphery. Unlike other nanoimaging and analysis techniques, we demonstrate that our unique combination of this high-resolution imaging technique with polymer physics-based analysis enables us to (i) investigate the chromatin conformation within packing domains and (ii) quantify statistical descriptors of chromatin structure that are relevant to transcription. We observe that packing domains have heterogeneous morphological properties even within the same cell line, underlying the potential role of statistical chromatin packing in regulating gene expression within eukaryotic nuclei.
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Affiliation(s)
- Yue Li
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Vasundhara Agrawal
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Ranya K A Virk
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Eric Roth
- Department of Materials Sciences and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Wing Shun Li
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Adam Eshein
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Jane Frederick
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Kai Huang
- Shenzhen Bay Laboratory, Institute of Systems and Physical Biology, Shenzhen, 518132, China
| | - Luay Almassalha
- Medical Scientist Training Program, Feinberg School of Medicine, Northwestern University, Evanston, IL, 60611, USA
| | - Reiner Bleher
- Department of Materials Sciences and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Marcelo A Carignano
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Igal Szleifer
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA.,Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Vinayak P Dravid
- Department of Materials Sciences and Engineering, Northwestern University, Evanston, IL, 60208, USA.
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA.
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8
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Razin SV, Zhegalova IV, Kantidze OL. Domain Model of Eukaryotic Genome Organization: From DNA Loops Fixed on the Nuclear Matrix to TADs. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:667-680. [PMID: 36154886 DOI: 10.1134/s0006297922070082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/18/2022] [Accepted: 06/22/2022] [Indexed: 06/16/2023]
Abstract
The article reviews the development of ideas on the domain organization of eukaryotic genome, with special attention on the studies of DNA loops anchored to the nuclear matrix and their role in the emergence of the modern model of eukaryotic genome spatial organization. Critical analysis of results demonstrating that topologically associated chromatin domains are structural-functional blocks of the genome supports the notion that these blocks are fundamentally different from domains whose existence was proposed by the domain hypothesis of eukaryotic genome organization formulated in the 1980s. Based on the discussed evidence, it is concluded that the model postulating that eukaryotic genome is built from uniformly organized structural-functional blocks has proven to be untenable.
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Affiliation(s)
- Sergey V Razin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Irina V Zhegalova
- Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia
- Kharkevich Institute for Information Transmission Problems, Moscow, 127051, Russia
| | - Omar L Kantidze
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
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9
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Hübner B, von Otter E, Ahsan B, Wee ML, Henriksson S, Ludwig A, Sandin S. Ultrastructure and nuclear architecture of telomeric chromatin revealed by correlative light and electron microscopy. Nucleic Acids Res 2022; 50:5047-5063. [PMID: 35489064 PMCID: PMC9122609 DOI: 10.1093/nar/gkac309] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 04/07/2022] [Accepted: 04/19/2022] [Indexed: 11/25/2022] Open
Abstract
Telomeres, the ends of linear chromosomes, are composed of repetitive DNA sequences, histones and a protein complex called shelterin. How DNA is packaged at telomeres is an outstanding question in the field with significant implications for human health and disease. Here, we studied the architecture of telomeres and their spatial association with other chromatin domains in different cell types using correlative light and electron microscopy. To this end, the shelterin protein TRF1 or TRF2 was fused in tandem to eGFP and the peroxidase APEX2, which provided a selective and electron-dense label to interrogate telomere organization by transmission electron microscopy, electron tomography and scanning electron microscopy. Together, our work reveals, for the first time, ultrastructural insight into telomere architecture. We show that telomeres are composed of a dense and highly compacted mesh of chromatin fibres. In addition, we identify marked differences in telomere size, shape and chromatin compaction between cancer and non-cancer cells and show that telomeres are in direct contact with other heterochromatin regions. Our work resolves the internal architecture of telomeres with unprecedented resolution and advances our understanding of how telomeres are organized in situ.
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Affiliation(s)
- Barbara Hübner
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Eric von Otter
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Bilal Ahsan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Mei Ling Wee
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Sara Henriksson
- Umeå Centre for Electron Microscopy, Umeå University, Chemical Biological Centre (KBC) Building, Linnaeus väg 6, SE-90736 Umeå, Sweden
| | - Alexander Ludwig
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Sara Sandin
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
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10
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Ma OX, Chong WG, Lee JKE, Cai S, Siebert CA, Howe A, Zhang P, Shi J, Surana U, Gan L. Cryo-ET detects bundled triple helices but not ladders in meiotic budding yeast. PLoS One 2022; 17:e0266035. [PMID: 35421110 PMCID: PMC9009673 DOI: 10.1371/journal.pone.0266035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 03/13/2022] [Indexed: 11/19/2022] Open
Abstract
In meiosis, cells undergo two sequential rounds of cell division, termed meiosis I and meiosis II. Textbook models of the meiosis I substage called pachytene show that nuclei have conspicuous 100-nm-wide, ladder-like synaptonemal complexes and ordered chromatin loops. It remains unknown if these cells have any other large, meiosis-related intranuclear structures. Here we present cryo-ET analysis of frozen-hydrated budding yeast cells before, during, and after pachytene. We found no cryo-ET densities that resemble dense ladder-like structures or ordered chromatin loops. Instead, we found large numbers of 12-nm-wide triple-helices that pack into ordered bundles. These structures, herein called meiotic triple helices (MTHs), are present in meiotic cells, but not in interphase cells. MTHs are enriched in the nucleus but not enriched in the cytoplasm. Bundles of MTHs form at the same timeframe as synaptonemal complexes (SCs) in wild-type cells and in mutant cells that are unable to form SCs. These results suggest that in yeast, SCs coexist with previously unreported large, ordered assemblies.
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Affiliation(s)
- Olivia X. Ma
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Wen Guan Chong
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Joy K. E. Lee
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shujun Cai
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - C. Alistair Siebert
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Andrew Howe
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Peijun Zhang
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jian Shi
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Uttam Surana
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Proteos, Singapore
- Bioprocessing Technology Institute, A*STAR, Singapore, Singapore
- Biotransformation Innovation Platform, A*STAR, Singapore, Singapore
- Department of Pharmacology, National University of Singapore, Singapore, Singapore
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
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11
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Hammonds EF, Harwig MC, Paintsil EA, Tillison EA, Hill RB, Morrison EA. Histone H3 and H4 tails play an important role in nucleosome phase separation. Biophys Chem 2022; 283:106767. [PMID: 35158124 PMCID: PMC8963862 DOI: 10.1016/j.bpc.2022.106767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 11/28/2022]
Abstract
Chromatin organization and its dynamic regulation are crucial in governing the temporal and spatial accessibility of DNA for proper gene expression. Disordered chains of nucleosomes comprise the basis of eukaryotic chromatin, forming higher-level organization across a range of length scales. Models of chromatin organization involving phase separation driven by chromatin-associating proteins have been proposed. More recently, evidence has emerged that nucleosome arrays can phase separate in the absence of other protein factors, yet questions remain regarding the molecular basis of chromatin phase separation that governs this dynamic nuclear organization. Here, we break chromatin down into its most basic subunit, the nucleosome core particle, and investigate phase separation using turbidity assays in conjunction with differential interference contrast microscopy. We show that, at physiologically-relevant concentrations, this fundamental subunit of chromatin undergoes phase separation. Individually removing the H3 and H4 tails abrogates phase separation under the same conditions. Taking a reductionist approach to investigate H3 and H4 tail peptide interactions in-trans with DNA and nucleosome core particles supports the direct involvement of these tails in chromatin phase separation. These results provide insight into fundamental mechanisms underlying phase separation of chromatin, which starts at the level of the nucleosome core particle, and support that long-range inter-nucleosomal interactions are sufficient to drive phase separation at nuclear concentrations. Additionally, our data have implications for understanding crosstalk between histone tails and provide a lens through which to interpret the effect of histone post-translational modifications and sequence variants. STATEMENT OF SIGNIFICANCE: Emerging models propose that chromatin organization is based in phase separation, however, mechanisms that drive this dynamic nuclear organization are only beginning to be understood. Previous focus has been on phase separation driven by chromatin-associating proteins, but this has recently shifted to recognize a direct role of chromatin in phase separation. Here, we take a fundamental approach in understanding chromatin phase separation and present new findings that the basic subunit of chromatin, the nucleosome core particle, undergoes phase separation under physiological concentrations of nucleosome and monovalent salt. Furthermore, the histone H3 and H4 tails are involved in phase separation in a manner independent of histone-associating proteins. These data suggest that H3 and H4 tail epigenetic factors may modulate chromatin phase separation.
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Affiliation(s)
- Erin F Hammonds
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America
| | - Megan Cleland Harwig
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America
| | - Emeleeta A Paintsil
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America
| | - Emma A Tillison
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America; Medical Scientist Training Program, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America
| | - Emma A Morrison
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, United States of America.
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12
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Poulet A, Mishra LN, Téletchéa S, Hayes JJ, Jacob Y, Thiriet C, Duc C. Identification and characterization of histones in Physarum polycephalum evidence a phylogenetic vicinity of Mycetozoans to the animal kingdom. NAR Genom Bioinform 2021; 3:lqab107. [PMID: 34805990 PMCID: PMC8600027 DOI: 10.1093/nargab/lqab107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/12/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023] Open
Abstract
Physarum polycephalum belongs to Mycetozoans, a phylogenetic clade apart from the animal, plant and fungus kingdoms. Histones are nuclear proteins involved in genome organization and regulation and are among the most evolutionary conserved proteins within eukaryotes. Therefore, this raises the question of their conservation in Physarum and the position of this organism within the eukaryotic phylogenic tree based on histone sequences. We carried out a comprehensive study of histones in Physarum polycephalum using genomic, transcriptomic and molecular data. Our results allowed to identify the different isoforms of the core histones H2A, H2B, H3 and H4 which exhibit strong conservation of amino acid residues previously identified as subject to post-translational modifications. Furthermore, we also identified the linker histone H1, the most divergent histone, and characterized a large number of its PTMs by mass spectrometry. We also performed an in-depth investigation of histone genes and transcript structures. Histone proteins are highly conserved in Physarum and their characterization will contribute to a better understanding of the polyphyletic Mycetozoan group. Our data reinforce that P. polycephalum is evolutionary closer to animals than plants and located at the crown of the eukaryotic tree. Our study provides new insights in the evolutionary history of Physarum and eukaryote lineages.
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Affiliation(s)
- Axel Poulet
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT 06520-8103, USA
| | - Laxmi Narayan Mishra
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester 14620 NY, USA
| | - Stéphane Téletchéa
- Conception de protéines in silico, Université de Nantes, CNRS, UFIP, UMR 6286, Nantes, France
| | - Jeffrey J Hayes
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester 14620 NY, USA
| | - Yannick Jacob
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT 06520-8103, USA
| | - Christophe Thiriet
- Epigénétique et dynamique de la chromatine, Université de Nantes, CNRS, UFIP, UMR 6286, Nantes, France
| | - Céline Duc
- Epigénétique et dynamique de la chromatine, Université de Nantes, CNRS, UFIP, UMR 6286, Nantes, France
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13
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Hansen JC, Maeshima K, Hendzel MJ. The solid and liquid states of chromatin. Epigenetics Chromatin 2021; 14:50. [PMID: 34717733 PMCID: PMC8557566 DOI: 10.1186/s13072-021-00424-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 10/22/2021] [Indexed: 12/14/2022] Open
Abstract
The review begins with a concise description of the principles of phase separation. This is followed by a comprehensive section on phase separation of chromatin, in which we recount the 60 years history of chromatin aggregation studies, discuss the evidence that chromatin aggregation intrinsically is a physiologically relevant liquid-solid phase separation (LSPS) process driven by chromatin self-interaction, and highlight the recent findings that under specific solution conditions chromatin can undergo liquid-liquid phase separation (LLPS) rather than LSPS. In the next section of the review, we discuss how certain chromatin-associated proteins undergo LLPS in vitro and in vivo. Some chromatin-binding proteins undergo LLPS in purified form in near-physiological ionic strength buffers while others will do so only in the presence of DNA, nucleosomes, or chromatin. The final section of the review evaluates the solid and liquid states of chromatin in the nucleus. While chromatin behaves as an immobile solid on the mesoscale, nucleosomes are mobile on the nanoscale. We discuss how this dual nature of chromatin, which fits well the concept of viscoelasticity, contributes to genome structure, emphasizing the dominant role of chromatin self-interaction.
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Affiliation(s)
- Jeffrey C Hansen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA.
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, and Department of Genetics, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka, 411-8540, Japan.
| | - Michael J Hendzel
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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14
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Adhireksan Z, Sharma D, Lee PL, Bao Q, Padavattan S, Shum WK, Davey GE, Davey CA. Engineering nucleosomes for generating diverse chromatin assemblies. Nucleic Acids Res 2021; 49:e52. [PMID: 33590100 PMCID: PMC8136823 DOI: 10.1093/nar/gkab070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/09/2021] [Accepted: 02/04/2021] [Indexed: 01/01/2023] Open
Abstract
Structural characterization of chromatin is challenging due to conformational and compositional heterogeneity in vivo and dynamic properties that limit achievable resolution in vitro. Although the maximum resolution for solving structures of large macromolecular assemblies by electron microscopy has recently undergone profound increases, X-ray crystallographic approaches may still offer advantages for certain systems. One such system is compact chromatin, wherein the crystalline state recapitulates the crowded molecular environment within the nucleus. Here we show that nucleosomal constructs with cohesive-ended DNA can be designed that assemble into different types of circular configurations or continuous fibers extending throughout crystals. We demonstrate the utility of the method for characterizing nucleosome compaction and linker histone binding at near-atomic resolution but also advance its application for tackling further problems in chromatin structural biology and for generating novel types of DNA nanostructures. We provide a library of cohesive-ended DNA fragment expression constructs and a strategy for engineering DNA-based nanomaterials with a seemingly vast potential variety of architectures and histone chemistries.
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Affiliation(s)
- Zenita Adhireksan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
| | - Deepti Sharma
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
| | - Phoi Leng Lee
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
| | - Qiuye Bao
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Sivaraman Padavattan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Wayne K Shum
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
| | - Gabriela E Davey
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
| | - Curt A Davey
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, 636921, Singapore
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15
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Ghosh I, Atsuzawa K, Arai A, Ohmukai R, Kaneko Y. TEM observation of compacted DNA of Synechococcus elongatus PCC 7942 using DRAQ5 labeling with DAB photooxidation and osmium black. Microscopy (Oxf) 2021; 70:316-320. [PMID: 32986072 DOI: 10.1093/jmicro/dfaa058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/11/2020] [Accepted: 09/17/2020] [Indexed: 11/13/2022] Open
Abstract
To visualize the fine structure of compacted DNA of Synechococcus elongatus PCC 7942, which appears at a specific time in the regular light/dark cycle prior to cell division, ChromEM with some modifications was applied. After staining DNA with DRAQ5, the cells were fixed and irradiated by red laser in the presence of 3,3'-diaminobenzidine and subsequently fixed with OsO4. A system with He-Ne laser (633 nm) was set up for efficient irradiation of the bacterial cells in aqueous solution. The compacted DNA was visualized by transmission electron microscopy, in ultrathin sections as electron dense staining by osmium black.
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Affiliation(s)
- Ilika Ghosh
- Department of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
| | - Kimie Atsuzawa
- Comprehensive Analysis Center for Science, Saitama University, Saitama, 338-8570, Japan
| | - Aoi Arai
- Department of Natural Science, Graduate School of Education, Saitama University, Saitama, 338-8570, Japan
| | - Ryuzo Ohmukai
- Department of Natural Science, Faculty of Education, Saitama University, Saitama 338-8570, Japan
| | - Yasuko Kaneko
- Department of Natural Science, Faculty of Education; Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
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16
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Abstract
Genomic information is encoded on long strands of DNA, which are folded into chromatin and stored in a tiny nucleus. Nuclear chromatin is a negatively charged polymer composed of DNA, histones, and various nonhistone proteins. Because of its highly charged nature, chromatin structure varies greatly depending on the surrounding environment (e.g., cations, molecular crowding, etc.). New technologies to capture chromatin in living cells have been developed over the past 10 years. Our view on chromatin organization has drastically shifted from a regular and static one to a more variable and dynamic one. Chromatin forms numerous compact dynamic domains that act as functional units of the genome in higher eukaryotic cells and locally appear liquid-like. By changing DNA accessibility, these domains can govern various functions. Based on new evidences from versatile genomics and advanced imaging studies, we discuss the physical nature of chromatin in the crowded nuclear environment and how it is regulated.
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Affiliation(s)
- Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Shiori Iida
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
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17
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Zhou Z, Yan R, Jiang W, Irudayaraj JMK. Chromatin hierarchical branching visualized at the nanoscale by electron microscopy. NANOSCALE ADVANCES 2021; 3:1019-1028. [PMID: 34381959 PMCID: PMC8323808 DOI: 10.1039/d0na00359j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 11/12/2020] [Indexed: 06/13/2023]
Abstract
Chromatin is spatially organized in a hierarchical manner by virtue of single nucleosomes condensing into higher order chromatin structures, conferring various mechanical properties and biochemical signals. These higher order chromatin structures regulate genomic function by organization of the heterochromatin and euchromatin landscape. Less is known about its transition state from higher order heterochromatin to the lower order nucleosome form, and there is no information on its physical properties. We have developed a facile method of electron microscopy visualization to reveal the interphase chromatin in eukaryotic cells and its organization into hierarchical branching structures. We note that chromatin hierarchical branching can be distinguished at four levels, clearly indicating the stepwise transition from heterochromatin to euchromatin. The protein-DNA density across the chromatin fibers decreases during the transition from compacted heterochromatin to dispersed euchromatin. Moreover, the thickness of the chromatin ranges between 10 to 270 nm, and the controversial 30 nm chromatin fiber exists as a prominent intermediate structure. This study provides important insights into higher order chromatin organization which plays a key role in diseases such as cancer.
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Affiliation(s)
- Zhongwu Zhou
- Bindley Bioscience Center, Department of Agricultural and Biological Engineering, Purdue University West Lafayette IN 47907 USA
- The University of Texas at Austin NHB 4.120, 100 E. 24th St. Austin TX 78712 USA
| | - Rui Yan
- Markey Center for Structural Biology, Department of Biological Science, Purdue University West Lafayette IN 47907 USA
- Howard Hughes Medical Institute, Janelia Research Campus 19700 Helix Drive Asburn Virginia 20147 USA
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Science, Purdue University West Lafayette IN 47907 USA
| | - Joseph M K Irudayaraj
- Bindley Bioscience Center, Department of Agricultural and Biological Engineering, Purdue University West Lafayette IN 47907 USA
- Cancer Center at Illinois, Department of Bioengineering, College of Engineering, University of Illinois at Urbana-Champaign Urbana IL 61801 USA
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18
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Lobbia VR, Trueba Sanchez MC, van Ingen H. Beyond the Nucleosome: Nucleosome-Protein Interactions and Higher Order Chromatin Structure. J Mol Biol 2021; 433:166827. [PMID: 33460684 DOI: 10.1016/j.jmb.2021.166827] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 12/20/2022]
Abstract
The regulation of chromatin biology ultimately depends on the manipulation of its smallest subunit, the nucleosome. The proteins that bind and operate on the nucleosome do so, while their substrate is part of a polymer embedded in the dense nuclear environment. Their molecular interactions must in some way be tuned to deal with this complexity. Due to the rapid increase in the number of high-resolution structures of nucleosome-protein complexes and the increasing understanding of the cellular chromatin structure, it is starting to become clearer how chromatin factors operate in this complex environment. In this review, we analyze the current literature on the interplay between nucleosome-protein interactions and higher-order chromatin structure. We examine in what way nucleosomes-protein interactions can affect and can be affected by chromatin organization at the oligonucleosomal level. In addition, we review the characteristics of nucleosome-protein interactions that can cause phase separation of chromatin. Throughout, we hope to illustrate the exciting challenges in characterizing nucleosome-protein interactions beyond the nucleosome.
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Affiliation(s)
- Vincenzo R Lobbia
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Maria Cristina Trueba Sanchez
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Hugo van Ingen
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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19
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Strickfaden H, Tolsma TO, Sharma A, Underhill DA, Hansen JC, Hendzel MJ. Condensed Chromatin Behaves like a Solid on the Mesoscale In Vitro and in Living Cells. Cell 2020; 183:1772-1784.e13. [PMID: 33326747 DOI: 10.1016/j.cell.2020.11.027] [Citation(s) in RCA: 156] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/16/2020] [Accepted: 11/16/2020] [Indexed: 12/11/2022]
Abstract
The association of nuclear DNA with histones to form chromatin is essential for temporal and spatial control of eukaryotic genomes. In this study, we examined the physical state of condensed chromatin in vitro and in vivo. Our in vitro studies demonstrate that self-association of nucleosomal arrays under a wide range of solution conditions produces supramolecular condensates in which the chromatin is physically constrained and solid-like. By measuring DNA mobility in living cells, we show that condensed chromatin also exhibits solid-like behavior in vivo. Representative heterochromatin proteins, however, display liquid-like behavior and coalesce around the solid chromatin scaffold. Importantly, euchromatin and heterochromatin show solid-like behavior even under conditions that produce limited interactions between chromatin fibers. Our results reveal that condensed chromatin exists in a solid-like state whose properties resist external forces and create an elastic gel and provides a scaffold that supports liquid-liquid phase separation of chromatin binding proteins.
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Affiliation(s)
- Hilmar Strickfaden
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Thomas O Tolsma
- Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins, CO, USA
| | - Ajit Sharma
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - D Alan Underhill
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada; Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Jeffrey C Hansen
- Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins, CO, USA.
| | - Michael J Hendzel
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada; Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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20
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Kim Y, Yu H. Shaping of the 3D genome by the ATPase machine cohesin. Exp Mol Med 2020; 52:1891-1897. [PMID: 33268833 PMCID: PMC8080590 DOI: 10.1038/s12276-020-00526-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 01/07/2023] Open
Abstract
The spatial organization of the genome is critical for fundamental biological processes, including transcription, genome replication, and segregation. Chromatin is compacted and organized with defined patterns and proper dynamics during the cell cycle. Aided by direct visualization and indirect genome reconstruction tools, recent discoveries have advanced our understanding of how interphase chromatin is dynamically folded at the molecular level. Here, we review the current understanding of interphase genome organization with a focus on the major regulator of genome structure, the cohesin complex. We further discuss how cohesin harnesses the energy of ATP hydrolysis to shape the genome by extruding chromatin loops.
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Affiliation(s)
- Yoori Kim
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hongtao Yu
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- School of Life Sciences, Westlake University, 310024, Hangzhou, Zhejiang, China.
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21
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Adhireksan Z, Sharma D, Lee PL, Davey CA. Near-atomic resolution structures of interdigitated nucleosome fibres. Nat Commun 2020; 11:4747. [PMID: 32958761 PMCID: PMC7505979 DOI: 10.1038/s41467-020-18533-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/21/2020] [Indexed: 01/05/2023] Open
Abstract
Chromosome structure at the multi-nucleosomal level has remained ambiguous in spite of its central role in epigenetic regulation and genome dynamics. Recent investigations of chromatin architecture portray diverse modes of interaction within and between nucleosome chains, but how this is realized at the atomic level is unclear. Here we present near-atomic resolution crystal structures of nucleosome fibres that assemble from cohesive-ended dinucleosomes with and without linker histone. As opposed to adopting folded helical ‘30 nm’ structures, the fibres instead assume open zigzag conformations that are interdigitated with one another. Zigzag conformations obviate extreme bending of the linker DNA, while linker DNA size (nucleosome repeat length) dictates fibre configuration and thus fibre–fibre packing, which is supported by variable linker histone binding. This suggests that nucleosome chains have a predisposition to interdigitate with specific characteristics under condensing conditions, which rationalizes observations of local chromosome architecture and the general heterogeneity of chromatin structure. Crystal structures of nucleosome fibres assembled from cohesive-ended dinucleosomes with and without linker histone reveal open zigzag conformations that are interdigitated with one another, and suggest the role that linker DNA plays in observed variable fibre configurations and packing.
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Affiliation(s)
- Zenita Adhireksan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Deepti Sharma
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Phoi Leng Lee
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Curt A Davey
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore. .,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore.
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22
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Kantidze OL, Razin SV. Weak interactions in higher-order chromatin organization. Nucleic Acids Res 2020; 48:4614-4626. [PMID: 32313950 PMCID: PMC7229822 DOI: 10.1093/nar/gkaa261] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 12/20/2022] Open
Abstract
The detailed principles of the hierarchical folding of eukaryotic chromosomes have been revealed during the last two decades. Along with structures composing three-dimensional (3D) genome organization (chromatin compartments, topologically associating domains, chromatin loops, etc.), the molecular mechanisms that are involved in their establishment and maintenance have been characterized. Generally, protein-protein and protein-DNA interactions underlie the spatial genome organization in eukaryotes. However, it is becoming increasingly evident that weak interactions, which exist in biological systems, also contribute to the 3D genome. Here, we provide a snapshot of our current understanding of the role of the weak interactions in the establishment and maintenance of the 3D genome organization. We discuss how weak biological forces, such as entropic forces operating in crowded solutions, electrostatic interactions of the biomolecules, liquid-liquid phase separation, DNA supercoiling, and RNA environment participate in chromosome segregation into structural and functional units and drive intranuclear functional compartmentalization.
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Affiliation(s)
- Omar L Kantidze
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
| | - Sergey V Razin
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
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23
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24
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Maeshima K, Tamura S, Hansen JC, Itoh Y. Fluid-like chromatin: Toward understanding the real chromatin organization present in the cell. Curr Opin Cell Biol 2020; 64:77-89. [PMID: 32283330 DOI: 10.1016/j.ceb.2020.02.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/16/2020] [Accepted: 02/22/2020] [Indexed: 12/23/2022]
Abstract
Eukaryotic chromatin is a negatively charged polymer consisting of genomic DNA, histones, and various nonhistone proteins. Because of its highly charged character, the structure of chromatin varies greatly depending on the surrounding environment (i.e. cations etc.): from an extended 10-nm fiber, to a folded 30-nm fiber, to chromatin condensates/liquid-droplets. Over the last ten years, newly developed technologies have drastically shifted our view on chromatin from a static regular structure to a more irregular and dynamic one, locally like a fluid. Since no single imaging (or genomics) method can tell us everything and beautiful images (or models) can fool our minds, comprehensive analyses based on many technical approaches are important to capture actual chromatin organization inside the cell. Here we critically discuss our current view on chromatin and methodology used to support the view.
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Affiliation(s)
- Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan; Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka, 411-8540, Japan.
| | - Sachiko Tamura
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Jeffrey C Hansen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Yuji Itoh
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
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25
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Tonnemacher S, Eltsov M, Jakob B. Correlative Light and Electron Microscopy (CLEM) Analysis of Nuclear Reorganization Induced by Clustered DNA Damage Upon Charged Particle Irradiation. Int J Mol Sci 2020; 21:ijms21061911. [PMID: 32168789 PMCID: PMC7139895 DOI: 10.3390/ijms21061911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/28/2020] [Accepted: 03/09/2020] [Indexed: 01/12/2023] Open
Abstract
Chromatin architecture plays major roles in gene regulation as well as in the repair of DNA damaged by endogenous or exogenous factors, such as after radiation. Opening up the chromatin might provide the necessary accessibility for the recruitment and binding of repair factors, thus facilitating timely and correct repair. The observed formation of ionizing radiation-induced foci (IRIF) of factors, such as 53BP1, upon induction of DNA double-strand breaks have been recently linked to local chromatin decompaction. Using correlative light and electron microscopy (CLEM) in combination with DNA-specific contrasting for transmission electron microscopy or tomography, we are able to show that at the ultrastructural level, these DNA damage domains reveal a chromatin compaction and organization not distinguishable from regular euchromatin upon irradiation with carbon or iron ions. Low Density Areas (LDAs) at sites of particle-induced DNA damage, as observed after unspecific uranyl acetate (UA)-staining, are thus unlikely to represent pure chromatin decompaction. RNA-specific terbium-citrate (Tb) staining suggests rather a reduced RNA density contributing to the LDA phenotype. Our observations are discussed in the view of liquid-like phase separation as one of the mechanisms of regulating DNA repair.
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26
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Host AAA+ ATPase TER94 Plays Critical Roles in Building the Baculovirus Viral Replication Factory and Virion Morphogenesis. J Virol 2020; 94:JVI.01674-19. [PMID: 31896597 DOI: 10.1128/jvi.01674-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 12/19/2019] [Indexed: 12/21/2022] Open
Abstract
TER94 is a multifunctional AAA+ ATPase crucial for diverse cellular processes, especially protein quality control and chromatin dynamics in eukaryotic organisms. Many viruses, including coronavirus, herpesvirus, and retrovirus, coopt host cellular TER94 for optimal viral invasion and replication. Previous proteomics analysis identified the association of TER94 with the budded virions (BVs) of baculovirus, an enveloped insect large DNA virus. Here, the role of TER94 in the prototypic baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) life cycle was investigated. In virus-infected cells, TER94 accumulated in virogenic stroma (VS) at the early stage of infection and subsequently partially rearranged in the ring zone region. In the virions, TER94 was associated with the nucleocapsids of both BV and occlusion-derived virus (ODV). Inhibition of TER94 ATPase activity significantly reduced viral DNA replication and BV production. Electron/immunoelectron microscopy revealed that inhibition of TER94 resulted in the trapping of nucleocapsids within cytoplasmic vacuoles at the nuclear periphery for BV formation and blockage of ODV envelopment at a premature stage within infected nuclei, which appeared highly consistent with its pivotal function in membrane biogenesis. Further analyses showed that TER94 was recruited to the VS or subnuclear structures through interaction with viral early proteins LEF3 and helicase, whereas inhibition of TER94 activity blocked the proper localization of replication-related viral proteins and morphogenesis of VS, providing an explanation for its role in viral DNA replication. Taken together, these data indicated the crucial functions of TER94 at multiple steps of the baculovirus life cycle, including genome replication, BV formation, and ODV morphogenesis.IMPORTANCE TER94 constitutes an important AAA+ ATPase that associates with diverse cellular processes, including protein quality control, membrane fusion of the Golgi apparatus and endoplasmic reticulum network, nuclear envelope reformation, and DNA replication. To date, little is known regarding the role(s) of TER94 in the baculovirus life cycle. In this study, TER94 was found to play a crucial role in multiple steps of baculovirus infection, including viral DNA replication and BV and ODV formation. Further evidence showed that the membrane fission/fusion function of TER94 is likely to be exploited by baculovirus for virion morphogenesis. Moreover, TER94 could interact with the viral early proteins LEF3 and helicase to transport and further recruit viral replication-related proteins to establish viral replication factories. This study highlights the critical roles of TER94 as an energy-supplying chaperon in the baculovirus life cycle and enriches our knowledge regarding the biological function of this important host factor.
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27
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Shoaib M, Nair N, Sørensen CS. Chromatin Landscaping At Mitotic Exit Orchestrates Genome Function. Front Genet 2020; 11:103. [PMID: 32158468 PMCID: PMC7052122 DOI: 10.3389/fgene.2020.00103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 01/29/2020] [Indexed: 11/23/2022] Open
Abstract
Chromatin architecture is highly dynamic during different phases of cell cycle to accommodate DNA-based processes. This is particularly obvious during mitotic exit, where highly condensed rod-like chromatids need to be rapidly decondensed. Such chromatin structural transitions are tightly controlled and organized as any perturbance in this dynamic process can lead to genome dysfunction which may culminate in loss of cellular fitness. However, the mechanisms underlying cell cycle-dependent chromatin structural changes are not fully understood. In this mini review, we highlight our current knowledge of chromatin structural organization, focusing on mitotic exit. In this regard, we examine how nuclear processes are orchestrated during chromatin unfolding and compartmentalization and discuss the critical importance of cell cycle-controlled chromatin landscaping in maintaining genome integrity.
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Affiliation(s)
- Muhammad Shoaib
- Biotech Research and Innovation Centre (BRIC), Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nidhi Nair
- Biotech Research and Innovation Centre (BRIC), Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claus Storgaard Sørensen
- Biotech Research and Innovation Centre (BRIC), Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
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28
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Beseda T, Cápal P, Kubalová I, Schubert V, Doležel J, Šimková H. Mitotic chromosome organization: General rules meet species-specific variability. Comput Struct Biotechnol J 2020; 18:1311-1319. [PMID: 32612754 PMCID: PMC7305364 DOI: 10.1016/j.csbj.2020.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 10/31/2022] Open
Abstract
Research on the formation of mitotic chromosomes from interphase chromatin domains, ongoing for several decades, made significant progress in recent years. It was stimulated by the development of advanced microscopic techniques and implementation of chromatin conformation capture methods that provide new insights into chromosome ultrastructure. This review aims to summarize and compare several models of chromatin fiber folding to form mitotic chromosomes and discusses them in the light of the novel findings. Functional genomics studies in several organisms confirmed condensins and cohesins as the major players in chromosome condensation. Here we compare available data on the role of these proteins across lower and higher eukaryotes and point to differences indicating evolutionary different pathways to shape mitotic chromosomes. Moreover, we discuss a controversial phenomenon of the mitotic chromosome ultrastructure - chromosome cavities - and using our super-resolution microscopy data, we contribute to its elucidation.
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Affiliation(s)
- Tomáš Beseda
- Institute of Experimental Botany, Czech Acad. Sci., Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, CZ-77900 Olomouc, Czech Republic
| | - Petr Cápal
- Institute of Experimental Botany, Czech Acad. Sci., Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, CZ-77900 Olomouc, Czech Republic
| | - Ivona Kubalová
- The Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Corrensstrasse 3, D-06466 Seeland, Germany
| | - Veit Schubert
- The Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Corrensstrasse 3, D-06466 Seeland, Germany
| | - Jaroslav Doležel
- Institute of Experimental Botany, Czech Acad. Sci., Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, CZ-77900 Olomouc, Czech Republic
| | - Hana Šimková
- Institute of Experimental Botany, Czech Acad. Sci., Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, CZ-77900 Olomouc, Czech Republic
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29
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Chagin VO, Reinhart B, Becker A, Mortusewicz O, Jost KL, Rapp A, Leonhardt H, Cardoso MC. Processive DNA synthesis is associated with localized decompaction of constitutive heterochromatin at the sites of DNA replication and repair. Nucleus 2019; 10:231-253. [PMID: 31744372 PMCID: PMC6949026 DOI: 10.1080/19491034.2019.1688932] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 09/01/2019] [Accepted: 10/22/2019] [Indexed: 12/18/2022] Open
Abstract
Constitutive heterochromatin is considered as a functionally inert genome compartment, important for its architecture and stability. How such stable structure is maintained is not well understood. Here, we apply four different visualization schemes to label it and investigate its dynamics during DNA replication and repair. We show that replisomes assemble over the heterochromatin in a temporally ordered manner. Furthermore, heterochromatin undergoes transient decompaction locally at the active sites of DNA synthesis. Using selective laser microirradiation conditions that lead to damage repaired via processive DNA synthesis, we measured similarly local decompaction of heterochromatin. In both cases, we could not observe large-scale movement of heterochromatin to the domain surface. Instead, the processive DNA synthesis machinery assembled at the replication/repair sites. Altogether, our data are compatible with a progression of DNA replication/repair along the chromatin in a dynamic mode with localized and transient decompaction that does not globally remodels the whole heterochromatin compartment.
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Affiliation(s)
- Vadim O. Chagin
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Britta Reinhart
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Annette Becker
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | | | - K. Laurence Jost
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Alexander Rapp
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | | | - M. Cristina Cardoso
- Cell Biology & Epigenetics, Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
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30
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Chromatin Is Frequently Unknotted at the Megabase Scale. Biophys J 2019; 118:2268-2279. [PMID: 31818464 PMCID: PMC7202934 DOI: 10.1016/j.bpj.2019.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 11/20/2022] Open
Abstract
Knots in the human genome would greatly impact diverse cellular processes ranging from transcription to gene regulation. To date, it has not been possible to directly examine the genome in vivo for the presence of knots. Recently, methods for serial fluorescent in situ hybridization have made it possible to measure the three-dimensional position of dozens of consecutive genomic loci in vivo. However, the determination of whether genomic trajectories are knotted remains challenging because small errors in the localization of a single locus can transform an unknotted trajectory into a highly knotted trajectory and vice versa. Here, we use stochastic closure analysis to determine if a genomic trajectory is knotted in the setting of experimental noise. We analyze 4727 deposited genomic trajectories of a 2-Mb-long chromatin interval from human chromosome 21. For 243 of these trajectories, their knottedness could be reliably determined despite the possibility of localization errors. Strikingly, in each of these 243 cases, the trajectory was unknotted. We note a potential source of bias insofar as knotted contours may be more difficult to reliably resolve. Nevertheless, our data are consistent with a model in which, at the scales probed, the human genome is often free of knots.
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31
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Razin SV, Ulianov SV, Gavrilov AA. 3D Genomics. Mol Biol 2019; 53:802-812. [DOI: 10.1134/s0026893319060153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/01/2019] [Accepted: 06/03/2019] [Indexed: 08/30/2023]
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32
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Zhou Z, Li K, Yan R, Yu G, Gilpin CJ, Jiang W, Irudayaraj JMK. The transition structure of chromatin fibers at the nanoscale probed by cryogenic electron tomography. NANOSCALE 2019; 11:13783-13789. [PMID: 31211313 PMCID: PMC6688845 DOI: 10.1039/c9nr02042j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The naked DNA inside the nucleus interacts with proteins and RNAs forming a higher order chromatin structure to spatially and temporally control transcription in eukaryotic cells. The 30 nm chromatin fiber is one of the most important determinants of the regulation of eukaryotic transcription. However, the transition of chromatin from the 30 nm inactive higher order structure to the actively transcribed lower order nucleosomal arrays is unclear, which limits our understanding of eukaryotic transcription. Using a method to extract near-native eukaryotic chromatin, we revealed the chromatin structure at the transitional state from the 30 nm chromatin to multiple nucleosomal arrays by cryogenic electron tomography (cryo-ET). Reproducible electron microscopy images revealed that the transitional structure is a branching structure that the 30 nm chromatin hierarchically branches into lower order nucleosomal arrays, indicating chromatin compaction at different levels to control its accessibility during the interphase. We further observed that some of the chromatin fibers on the branching structure have a helix ribbon structure, while the others randomly twist together. Our finding of the chromatin helix ribbon structure on the extracted native chromatin revealed by cryo-ET indicates a complex higher order chromatin organization beyond the beads-on-a-string structure. The hierarchical branching and helix ribbon structure may provide mechanistic insights into how chromatin organization plays a central role in transcriptional regulation and other DNA-related biological processes during diseases such as cancer.
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Affiliation(s)
- Zhongwu Zhou
- Bindley Bioscience Center, Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA.
| | - Kunpeng Li
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, West Lafayette, IN 47907, USA
| | - Rui Yan
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, West Lafayette, IN 47907, USA
| | - Guimei Yu
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, West Lafayette, IN 47907, USA
| | - Christopher J Gilpin
- Life Science Microscopy Facility, Purdue University, West Lafayette, IN 47907, USA
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Science, Purdue University, West Lafayette, IN 47907, USA
| | - Joseph M K Irudayaraj
- Bindley Bioscience Center, Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA. and Department of Bioengineering, College of Engineering, 1103 Everitt Laboratory, 1406 W. Greet Street, Urbana, IL 61801, USA
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33
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Maeshima K, Ide S, Babokhov M. Dynamic chromatin organization without the 30-nm fiber. Curr Opin Cell Biol 2019; 58:95-104. [DOI: 10.1016/j.ceb.2019.02.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/08/2019] [Accepted: 02/14/2019] [Indexed: 12/24/2022]
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34
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H3K18Ac as a Marker of Cancer Progression and Potential Target of Anti-Cancer Therapy. Cells 2019; 8:cells8050485. [PMID: 31121824 PMCID: PMC6562857 DOI: 10.3390/cells8050485] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 02/07/2023] Open
Abstract
Acetylation and deacetylation are posttranslational modifications (PTMs) which affect the regulation of chromatin structure and its remodeling. Acetylation of histone 3 at lysine placed on position 18 (H3K18Ac) plays an important role in driving progression of many types of cancer, including breast, colon, lung, hepatocellular, pancreatic, prostate, and thyroid cancer. The aim of this review is to analyze and discuss the newest findings regarding the role of H3K18Ac and acetylation of other histones in carcinogenesis. We summarize the level of H3K18Ac in different cancer cell lines and analyze its association with patients’ outcomes, including overall survival (OS), progression-free survival (PFS), and disease-free survival (DFS). Finally, we describe future perspectives of cancer therapeutic strategies based on H3K18 modifications.
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35
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Parmar JJ, Woringer M, Zimmer C. How the Genome Folds: The Biophysics of Four-Dimensional Chromatin Organization. Annu Rev Biophys 2019; 48:231-253. [DOI: 10.1146/annurev-biophys-052118-115638] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The genetic information that instructs transcription and other cellular functions is carried by the chromosomes, polymers of DNA in complex with histones and other proteins. These polymers are folded inside nuclei five orders of magnitude smaller than their linear length, and many facets of this folding correlate with or are causally related to transcription and other cellular functions. Recent advances in sequencing and imaging-based techniques have enabled new views into several layers of chromatin organization. These experimental findings are accompanied by computational modeling efforts based on polymer physics that can provide mechanistic insights and quantitative predictions. Here, we review current knowledge of the main levels of chromatin organization, from the scale of nucleosomes to the entire nucleus, our current understanding of their underlying biophysical and molecular mechanisms, and some of their functional implications.
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Affiliation(s)
- Jyotsana J. Parmar
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
| | - Maxime Woringer
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
- Sorbonne Universités, CNRS, 75005 Paris, France
- Department of Molecular and Cell Biology, Li Ka Shing Center for Biomedical and Health Sciences, and CIRM Center of Excellence in Stem Cell Genomics, University of California, Berkeley, California 94720, USA
| | - Christophe Zimmer
- Unité Imagerie et Modélisation, CNRS UMR 3691, and C3BI (Center of Bioinformatics, Biostatistics and Integrative Biology), CNRS USR 3756, Institut Pasteur, 75015 Paris, France;, ,
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36
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de Wit H, Vallet A, Brutscher B, Koorsen G. NMR assignments of human linker histone H1x N-terminal domain and globular domain in the presence and absence of perchlorate. BIOMOLECULAR NMR ASSIGNMENTS 2019; 13:249-254. [PMID: 30868366 DOI: 10.1007/s12104-019-09886-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
Human linker histone H1 plays a seminal role in eukaryotic DNA packaging. H1 has a tripartite structure consisting of a central, conserved globular domain, which adopts a winged-helix fold, flanked by two variable N- and C-terminal domains. Here we present the backbone resonance assignments of the N-terminal domain and globular domain of human linker histone H1x in the presence and absence of the secondary structure stabilizer sodium perchlorate. Analysis of chemical shift changes between the two conditions is consistent with induction of transient secondary structural elements in the N-terminal domain of H1x in high ionic strength, which suggests that the N-terminal domain adopts significant alpha-helical conformations in the presence of DNA.
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Affiliation(s)
- Herna de Wit
- University of Johannesburg, PO Box 524, Auckland Park, Johannesburg, South Africa
| | - Alicia Vallet
- University Grenoble Alpes, CEA, CNRS, IBS, 38000, Grenoble, France
| | | | - Gerrit Koorsen
- University of Johannesburg, PO Box 524, Auckland Park, Johannesburg, South Africa.
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37
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Olins DE, Olins AL. Epichromatin and chromomeres: a 'fuzzy' perspective. Open Biol 2019; 8:rsob.180058. [PMID: 29875200 PMCID: PMC6030114 DOI: 10.1098/rsob.180058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 05/09/2018] [Indexed: 12/17/2022] Open
Abstract
'Epichromatin', the surface of chromatin beneath the interphase nuclear envelope (NE) or at the surface of mitotic chromosomes, was discovered by immunostaining with a specific bivalent mouse monoclonal anti-nucleosome antibody (mAb PL2-6). 'Chromomeres', punctate chromatin particles approximately 200-300 nm in diameter, identified throughout the interphase chromatin and along mitotic chromosomes, were observed by immunostaining with the monovalent papain-derived Fab fragments of bivalent PL2-6. The specific target for PL2-6 appears to include the nucleosome acidic patch. Thus, within the epichromatin and chromomeric regions, this epitope is 'exposed'. Considering that histones possess unstructured 'tails' (i.e. intrinsically disordered peptide regions, IDPR), our perception of these chromatin regions becomes more 'fuzzy' (less defined). We suggest that epichromatin cationic tails facilitate interactions with anionic components of NE membranes. We also suggest that the unstructured histone tails (especially, histone H1 tails), with their presumed promiscuous binding, establish multivalent binding that stabilizes each chromomere as a unit of chromatin higher order structure. We propose an 'unstructured stability' hypothesis, which postulates that the stability of epichromatin and chromomeres (as well as other nuclear chromatin structures) is a consequence of the collective contributions of numerous weak histone IDPR binding interactions arising from the multivalent nucleosome, analogous to antibody avidity.
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Affiliation(s)
- Donald E Olins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA
| | - Ada L Olins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA
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38
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Post-translational modifications and chromatin dynamics. Essays Biochem 2019; 63:89-96. [DOI: 10.1042/ebc20180067] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 12/21/2022]
Abstract
Abstract
The dynamic structure of chromatin is linked to gene regulation and many other biological functions. Consequently, it is of importance to understand the factors that regulate chromatin dynamics. While the in vivo analysis of chromatin has verified that histone post-translational modifications play a role in modulating DNA accessibility, the complex nuclear environment and multiplicity of modifications prevents clear conclusions as to how individual modifications influence chromatin dynamics in the cell. For this reason, in vitro analyses of model reconstituted nucleosomal arrays has been pivotal in understanding the dynamic nature of chromatin compaction and the affects that specific post-translational modifications can have on the higher order chromatin structure. In this mini-review, we briefly describe the dynamic chromatin structures that have been observed in vitro and the environmental conditions that give rise to these various conformational states. Our focus then turns to a discussion of the specific histone post-translational modifications that have been shown to alter formation of these higher order chromatin structures in vitro and how this may relate to the biological state and accessibility of chromatin in vivo.
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39
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Fritz AJ, Sehgal N, Pliss A, Xu J, Berezney R. Chromosome territories and the global regulation of the genome. Genes Chromosomes Cancer 2019; 58:407-426. [PMID: 30664301 DOI: 10.1002/gcc.22732] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/11/2019] [Accepted: 01/12/2019] [Indexed: 12/29/2022] Open
Abstract
Spatial positioning is a fundamental principle governing nuclear processes. Chromatin is organized as a hierarchy from nucleosomes to Mbp chromatin domains (CD) or topologically associating domains (TADs) to higher level compartments culminating in chromosome territories (CT). Microscopic and sequencing techniques have substantiated chromatin organization as a critical factor regulating gene expression. For example, enhancers loop back to interact with their target genes almost exclusively within TADs, distally located coregulated genes reposition into common transcription factories upon activation, and Mbp CDs exhibit dynamic motion and configurational changes in vivo. A longstanding question in the nucleus field is whether an interactive nuclear matrix provides a direct link between structure and function. The findings of nonrandom radial positioning of CT within the nucleus suggest the possibility of preferential interaction patterns among populations of CT. Sequential labeling up to 10 CT followed by application of computer imaging and geometric graph mining algorithms revealed cell-type specific interchromosomal networks (ICN) of CT that are altered during the cell cycle, differentiation, and cancer progression. It is proposed that the ICN correlate with the global level of genome regulation. These approaches also demonstrated that the large scale 3-D topology of CT is specific for each CT. The cell-type specific proximity of certain chromosomal regions in normal cells may explain the propensity of distinct translocations in cancer subtypes. Understanding how genes are dysregulated upon disruption of the normal "wiring" of the nucleus by translocations, deletions, and amplifications that are hallmarks of cancer, should enable more targeted therapeutic strategies.
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Affiliation(s)
- Andrew J Fritz
- Department of Biochemistry and University of Vermont Cancer Center, The University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Nitasha Sehgal
- Department of Biological Sciences, University at Buffalo, Buffalo, New York
| | - Artem Pliss
- Institute for Lasers, Photonics and Biophotonics and the Department of Chemistry, University at Buffalo, Buffalo, New York
| | - Jinhui Xu
- Department of Computer Science and Engineering, University at Buffalo, Buffalo, New York
| | - Ronald Berezney
- Department of Biological Sciences, University at Buffalo, Buffalo, New York
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40
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Schwartz U, Németh A, Diermeier S, Exler JH, Hansch S, Maldonado R, Heizinger L, Merkl R, Längst G. Characterizing the nuclease accessibility of DNA in human cells to map higher order structures of chromatin. Nucleic Acids Res 2019; 47:1239-1254. [PMID: 30496478 PMCID: PMC6379673 DOI: 10.1093/nar/gky1203] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/17/2018] [Accepted: 11/22/2018] [Indexed: 12/22/2022] Open
Abstract
Packaging of DNA into chromatin regulates DNA accessibility and consequently all DNA-dependent processes. The nucleosome is the basic packaging unit of DNA forming arrays that are suggested, by biochemical studies, to fold hierarchically into ordered higher-order structures of chromatin. This organization has been recently questioned using microscopy techniques, proposing an irregular structure. To address the principles of chromatin organization, we applied an in situ differential MNase-seq strategy and analyzed in silico the results of complete and partial digestions of human chromatin. We investigated whether different levels of chromatin packaging exist in the cell. We assessed the accessibility of chromatin within distinct domains of kb to Mb genomic regions, performed statistical analyses and computer modelling. We found no difference in MNase accessibility, suggesting no difference in fiber folding between domains of euchromatin and heterochromatin or between other sequence and epigenomic features of chromatin. Thus, our data suggests the absence of differentially organized domains of higher-order structures of chromatin. Moreover, we identified only local structural changes, with individual hyper-accessible nucleosomes surrounding regulatory elements, such as enhancers and transcription start sites. The regulatory sites per se are occupied with structurally altered nucleosomes, exhibiting increased MNase sensitivity. Our findings provide biochemical evidence that supports an irregular model of large-scale chromatin organization.
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Affiliation(s)
- Uwe Schwartz
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Attila Németh
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Sarah Diermeier
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Josef H Exler
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Stefan Hansch
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Rodrigo Maldonado
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
| | - Leonhard Heizinger
- Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany
| | - Rainer Merkl
- Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany
| | - Gernot Längst
- Department of Biochemistry III, University of Regensburg, University of Regensburg, 93040 Regensburg, Germany
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41
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de Jong BE, Brouwer TB, Kaczmarczyk A, Visscher B, van Noort J. Rigid Basepair Monte Carlo Simulations of One-Start and Two-Start Chromatin Fiber Unfolding by Force. Biophys J 2018; 115:1848-1859. [PMID: 30366627 PMCID: PMC6303278 DOI: 10.1016/j.bpj.2018.10.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 09/21/2018] [Accepted: 10/05/2018] [Indexed: 12/30/2022] Open
Abstract
The organization of chromatin in 30 nm fibers remains a topic of debate. Here, we quantify the mechanical properties of the linker DNA and evaluate the impact of these properties on chromatin fiber folding. We extended a rigid basepair DNA model to include (un)wrapping of nucleosomal DNA and (un)stacking of nucleosomes in one-start and two-start chromatin fibers. Monte Carlo simulations that mimic single-molecule force spectroscopy experiments of folded nucleosomal arrays reveal different stages of unfolding as a function of force and are largely consistent with a two-start folding for 167 and one-start folding for 197 nucleosome repeat length fibers. The major insight is that nucleosome unstacking and subsequent unwrapping is not necessary to obtain quantitative agreement with experimental force extension curves up to the overstretching plateau of folded chromatin fibers at 3-5 pN. Nucleosome stacking appears better accommodated in one-start than in two-start conformations, and we suggest that this difference can compensate the increased energy for bending the linker DNA. Overall, these simulations capture the dynamic structure of chromatin fibers while maintaining realistic physical properties of the linker DNA.
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Affiliation(s)
- Babette E de Jong
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Thomas B Brouwer
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Artur Kaczmarczyk
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Bert Visscher
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - John van Noort
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands.
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42
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Maeshima K, Tamura S, Shimamoto Y. Chromatin as a nuclear spring. Biophys Physicobiol 2018; 15:189-195. [PMID: 30349803 PMCID: PMC6194950 DOI: 10.2142/biophysico.15.0_189] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/30/2018] [Indexed: 12/15/2022] Open
Abstract
The nucleus in eukaryotic cells is the site for genomic functions such as RNA transcription, DNA replication, and DNA repair/recombination. However, the nucleus is subjected to various mechanical forces associated with diverse cellular activities, including contraction, migration, and adhesion. Although it has long been assumed that the lamina structure, underlying filamentous mesh-work of the nuclear envelope, plays an important role in resisting mechanical forces, the involvement of compact chromatin in mechanical resistance has also recently been suggested. However, it is still unclear how chromatin functions to cope with the stresses. To address this issue, we studied the mechanical responses of human cell nuclei by combining a force measurement microscopy setup with controlled biochemical manipulation of chromatin. We found that nuclei with condensed chromatin possess significant elastic rigidity, whereas the nuclei with a decondensed chromatin are considerably soft. Further analyses revealed that the linker DNA and nucleosome-nucleosome interactions via histone tails in the chromatin act together to generate a spring-like restoring force that resists nuclear deformation. The elastic restoring force is likely to be generated by condensed chromatin domains, consisting of interdigitated or "melted" 10-nm nucleosome fibers. Together with other recent studies, it is suggested that chromatin functions not only as a "memory device" to store, replicate, and express the genetic information for various cellular functions but also as a "nuclear spring" to resist and respond to mechanical forces.
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Affiliation(s)
- Kazuhiro Maeshima
- Biological Macromolecules Laboratory, Structural Biology Center, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Tamura
- Biological Macromolecules Laboratory, Structural Biology Center, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Yuta Shimamoto
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan.,Quantitative Mechanobiology Laboratory, Center for Frontier Research, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
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Cai S, Böck D, Pilhofer M, Gan L. The in situ structures of mono-, di-, and trinucleosomes in human heterochromatin. Mol Biol Cell 2018; 29:2450-2457. [PMID: 30091658 PMCID: PMC6233054 DOI: 10.1091/mbc.e18-05-0331] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The in situ three-dimensional organization of chromatin at the nucleosome and oligonucleosome levels is unknown. Here we use cryo-electron tomography to determine the in situ structures of HeLa nucleosomes, which have canonical core structures and asymmetric, flexible linker DNA. Subtomogram remapping suggests that sequential nucleosomes in heterochromatin follow irregular paths at the oligonucleosome level. This basic principle of higher-order repressive chromatin folding is compatible with the conformational variability of the two linker DNAs at the single-nucleosome level.
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Affiliation(s)
- Shujun Cai
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
| | - Désirée Böck
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Martin Pilhofer
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
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Gil RS, Vagnarelli P. Protein phosphatases in chromatin structure and function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:90-101. [PMID: 30036566 PMCID: PMC6227384 DOI: 10.1016/j.bbamcr.2018.07.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/29/2018] [Accepted: 07/18/2018] [Indexed: 12/19/2022]
Abstract
Chromatin structure and dynamics are highly controlled and regulated processes that play an essential role in many aspects of cell biology. The chromatin transition stages and the factors that control this process are regulated by post-translation modifications, including phosphorylation. While the role of protein kinases in chromatin dynamics has been quite well studied, the nature and regulation of the counteracting phosphatases represent an emerging field but are still at their infancy. In this review we summarize the current literature on phosphatases involved in the regulation of chromatin structure and dynamics, with emphases on the major knowledge gaps that should require attention and more investigation.
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Affiliation(s)
- Raquel Sales Gil
- Colleges of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK
| | - Paola Vagnarelli
- Colleges of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK.
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Zhou BR, Jiang J, Ghirlando R, Norouzi D, Sathish Yadav KN, Feng H, Wang R, Zhang P, Zhurkin V, Bai Y. Revisit of Reconstituted 30-nm Nucleosome Arrays Reveals an Ensemble of Dynamic Structures. J Mol Biol 2018; 430:3093-3110. [PMID: 29959925 DOI: 10.1016/j.jmb.2018.06.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 06/05/2018] [Accepted: 06/05/2018] [Indexed: 01/23/2023]
Abstract
It has long been suggested that chromatin may form a fiber with a diameter of ~30 nm that suppresses transcription. Despite nearly four decades of study, the structural nature of the 30-nm chromatin fiber and conclusive evidence of its existence in vivo remain elusive. The key support for the existence of specific 30-nm chromatin fiber structures is based on the determination of the structures of reconstituted nucleosome arrays using X-ray crystallography and single-particle cryo-electron microscopy coupled with glutaraldehyde chemical cross-linking. Here we report the characterization of these nucleosome arrays in solution using analytical ultracentrifugation, NMR, and small-angle X-ray scattering. We found that the physical properties of these nucleosome arrays in solution are not consistent with formation of just a few discrete structures of nucleosome arrays. In addition, we obtained a crystal of the nucleosome in complex with the globular domain of linker histone H5 that shows a new form of nucleosome packing and suggests a plausible alternative compact conformation for nucleosome arrays. Taken together, our results challenge the key evidence for the existence of a limited number of structures of reconstituted nucleosome arrays in solution by revealing that the reconstituted nucleosome arrays are actually best described as an ensemble of various conformations with a zigzagged arrangement of nucleosomes. Our finding has implications for understanding the structure and function of chromatin in vivo.
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Affiliation(s)
- Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiansheng Jiang
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Davood Norouzi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - K N Sathish Yadav
- Laboratory of Structural Biophysics, National Cancer Institute, Frederick, MD 21701, USA
| | - Hanqiao Feng
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rui Wang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ping Zhang
- Laboratory of Structural Biophysics, National Cancer Institute, Frederick, MD 21701, USA
| | - Victor Zhurkin
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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46
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Murayama Y. DNA entry, exit and second DNA capture by cohesin: insights from biochemical experiments. Nucleus 2018; 9:492-502. [PMID: 30205748 PMCID: PMC6244732 DOI: 10.1080/19491034.2018.1516486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/28/2018] [Accepted: 08/16/2018] [Indexed: 12/23/2022] Open
Abstract
Cohesin is a ring-shaped, multi-subunit ATPase assembly that is fundamental to the spatiotemporal organization of chromosomes. The ring establishes a variety of chromosomal structures including sister chromatid cohesion and chromatin loops. At the core of the ring is a pair of highly conserved SMC (Structural Maintenance of Chromosomes) proteins, which are closed by the flexible kleisin subunit. In common with other essential SMC complexes including condensin and the SMC5-6 complex, cohesin encircles DNA inside its cavity, with the aid of HEAT (Huntingtin, elongation factor 3, protein phosphatase 2A and TOR) repeat auxiliary proteins. Through this topological embrace, cohesin is thought to establish a series of intra- and interchromosomal interactions by tethering more than one DNA molecule. Recent progress in biochemical reconstitution of cohesin provides molecular insights into how this ring complex topologically binds and mediates DNA-DNA interactions. Here, I review these studies and discuss how cohesin mediates such chromosome interactions.
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Affiliation(s)
- Yasuto Murayama
- Chromosome Biochemistry Laboratory, Center for Frontier Research, National Institute of Genetics, Mishima, Shizuoka, Japan
- Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Shizuoka, Japan
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