1
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Chen P, Li G, Li W. Nucleosome Dynamics Derived at the Single-Molecule Level Bridges Its Structures and Functions. JACS AU 2024; 4:866-876. [PMID: 38559720 PMCID: PMC10976579 DOI: 10.1021/jacsau.3c00658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 04/04/2024]
Abstract
Nucleosome, the building block of chromatin, plays pivotal roles in all DNA-related processes. While cryogenic-electron microscopy (cryo-EM) has significantly advanced our understanding of nucleosome structures, the emerging field of single-molecule force spectroscopy is illuminating their dynamic properties. This technique is crucial for revealing how nucleosome behavior is influenced by chaperones, remodelers, histone variants, and post-translational modifications, particularly in their folding and unfolding mechanisms under tension. Such insights are vital for deciphering the complex interplay in nucleosome assembly and structural regulation, highlighting the nucleosome's versatility in response to DNA activities. In this Perspective, we aim to consolidate the latest advancements in nucleosome dynamics, with a special focus on the revelations brought forth by single-molecule manipulation. Our objective is to highlight the insights gained from studying nucleosome dynamics through this innovative approach, emphasizing the transformative impact of single-molecule manipulation techniques in the field of chromatin research.
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Affiliation(s)
- Ping Chen
- National
Laboratory of Biomacromolecules and Key Laboratory of Epigenetic Regulation
and Intervention, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P. R. China
- Department
of Immunology, School of Basic Medical Sciences, Beijing Key Laboratory
for Tumor Invasion and Metastasis, Capital
Medical University, Beijing 100069, P. R. China
| | - Guohong Li
- National
Laboratory of Biomacromolecules and Key Laboratory of Epigenetic Regulation
and Intervention, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P. R. China
- University
of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Wei Li
- National
Laboratory of Biomacromolecules and Key Laboratory of Epigenetic Regulation
and Intervention, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P. R. China
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2
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Tomkuvienė M, Meier M, Ikasalaitė D, Wildenauer J, Kairys V, Klimašauskas S, Manelytė L. Enhanced nucleosome assembly at CpG sites containing an extended 5-methylcytosine analogue. Nucleic Acids Res 2022; 50:6549-6561. [PMID: 35648439 PMCID: PMC9226530 DOI: 10.1093/nar/gkac444] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 05/05/2022] [Accepted: 05/16/2022] [Indexed: 02/01/2023] Open
Abstract
Methylation of cytosine to 5-methylcytosine (mC) at CpG sites is a prevalent reversible epigenetic mark in vertebrates established by DNA methyltransferases (MTases); the attached methyl groups can alter local structure of DNA and chromatin as well as binding of dedicated proteins. Nucleosome assembly on methylated DNA has been studied extensively, however little is known how the chromatin structure is affected by larger chemical variations in the major groove of DNA. Here, we studied the nucleosome formation in vitro on DNA containing an extended 5mC analog, 5-(6-azidohex-2-ynyl)cytosine (ahyC) installed at biological relevant CpG sites. We found that multiple ahyC residues on 80-Widom and Hsp70 promoter DNA fragments proved compatible with nucleosome assembly. Moreover, unlike mC, ahyC increases the affinity of histones to the DNA, partially altering nucleosome positioning, stability, and the action of chromatin remodelers. Based on molecular dynamics calculations, we suggest that these new features are due to increased DNA flexibility at ahyC-modified sites. Our findings provide new insights into the biophysical behavior of modified DNA and open new ways for directed design of synthetic nucleosomes.
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Affiliation(s)
- Miglė Tomkuvienė
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius LT-10257, Lithuania
| | - Markus Meier
- Biochemistry III, University of Regensburg, Regensburg, Bavaria, DE-93053, Germany
| | - Diana Ikasalaitė
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius LT-10257, Lithuania
| | - Julia Wildenauer
- Biochemistry III, University of Regensburg, Regensburg, Bavaria, DE-93053, Germany
| | - Visvaldas Kairys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius LT-10257, Lithuania
| | - Saulius Klimašauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius LT-10257, Lithuania
| | - Laura Manelytė
- Biochemistry III, University of Regensburg, Regensburg, Bavaria, DE-93053, Germany
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3
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Bosire R, Fadel L, Mocsár G, Nánási P, Sen P, Sharma AK, Naseem MU, Kovács A, Kugel J, Kroemer G, Vámosi G, Szabó G. Doxorubicin impacts chromatin binding of HMGB1, Histone H1 and retinoic acid receptor. Sci Rep 2022; 12:8087. [PMID: 35577872 PMCID: PMC9110345 DOI: 10.1038/s41598-022-11994-z] [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: 12/25/2021] [Accepted: 05/03/2022] [Indexed: 11/10/2022] Open
Abstract
Doxorubicin (Dox), a widely used anticancer DNA-binding drug, affects chromatin in multiple ways, and these effects contribute to both its efficacy and its dose-limiting side effects, especially cardiotoxicity. Here, we studied the effects of Dox on the chromatin binding of the architectural proteins high mobility group B1 (HMGB1) and the linker histone H1, and the transcription factor retinoic acid receptor (RARα) by fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS) in live cells. At lower doses, Dox increased the binding of HMGB1 to DNA while decreasing the binding of the linker histone H1. At higher doses that correspond to the peak plasma concentrations achieved during chemotherapy, Dox reduced the binding of HMGB1 as well. This biphasic effect is interpreted in terms of a hierarchy of competition between the ligands involved and Dox-induced local conformational changes of nucleosome-free DNA. Combined, FRAP and FCS mobility data suggest that Dox decreases the overall binding of RARα to DNA, an effect that was only partially overcome by agonist binding. The intertwined interactions described are likely to contribute to both the effects and side effects of Dox.
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Affiliation(s)
- Rosevalentine Bosire
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, Debrecen, Hungary
| | - Lina Fadel
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Gábor Mocsár
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter Nánási
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Pialy Sen
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Anshu Kumar Sharma
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Kovács
- Department of Radiation Therapy, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jennifer Kugel
- Department of Biochemistry, University of Colorado, Boulder, USA
| | - Guido Kroemer
- Centre de Recherche Des Cordeliers, Equipe Labellisée Par La Ligue Contre Le Cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France.,Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France.,Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
| | - György Vámosi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
| | - Gábor Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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4
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Isocyanide Substitution in Acridine Orange Shifts DNA Damage-Mediated Phototoxicity to Permeabilization of the Lysosomal Membrane in Cancer Cells. Cancers (Basel) 2021; 13:cancers13225652. [PMID: 34830806 PMCID: PMC8616321 DOI: 10.3390/cancers13225652] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/02/2021] [Accepted: 11/09/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Aside from tissue cell renewal, tumor cells are also produced every day. In ordinary conditions, immunologically controlled cell death mechanisms limit cancer development. There are several cell death processes used for how normal and tumor cells are eliminated at the end of their lifespan. In cancer therapy, cells dying via immunological death are more efficiently eradicated than cells dying by classical apoptosis. Photodynamic treatments with some photosensitizers target lysosomes. Lysosomal death diverts apoptosis to the immunologically more pertinent necrosis-like death pathways. Acridine orange (AO), a well-known photosensitizer, targets lysosomes as well. We have synthesized a new compound abbreviated as DM, a modified AO, and examined details of intracellular processes leading to photodynamic cell death. We have proven that DM targets lysosomes better than AO. Remarkably, with DM, we could visualize an abrupt nuclear DNA release from cells during the photodynamic process. Our work highlights which cellular events may enhance immunological cell death. Abstract In cancer therapy, immunogenic cell death eliminates tumor cells more efficiently than conventional apoptosis. During photodynamic therapy (PDT), some photosensitizer (PS) targeting lysosomes divert apoptosis to the immunologically more relevant necrosis-like cell death. Acridine orange (AO) is a PS targeting lysosome. We synthesized a new compound, 3-N,N-dimethylamino-6-isocyanoacridine (DM), a modified AO, aiming to target lysosomes better. To compare DM and AO, we studied optical properties, toxicity, cell internalization, and phototoxicity. In addition, light-mediated effects were monitored by the recently developed QUINESIn method on nuclei, and membrane stability, morphology, and function of lysosomes utilizing fluorescent probes by imaging cytometry in single cells. DM proved to be a better lysosomal marker at 405 nm excitation and lysed lysosomes more efficiently. AO injured DNA and histones more extensively than DM. Remarkably, DM’s optical properties helped visualize shockwaves of nuclear DNA released from cells during the PDT. The asymmetric polar modification of the AO leads to a new compound, DM, which has increased efficacy in targeting and disrupting lysosomes. Suitable AO modification may boost adaptive immune response making PDT more efficient.
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5
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Henn L, Szabó A, Imre L, Román Á, Ábrahám A, Vedelek B, Nánási P, Boros IM. Alternative linker histone permits fast paced nuclear divisions in early Drosophila embryo. Nucleic Acids Res 2020; 48:9007-9018. [PMID: 32710625 PMCID: PMC7498357 DOI: 10.1093/nar/gkaa624] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/16/2020] [Accepted: 07/14/2020] [Indexed: 01/09/2023] Open
Abstract
In most animals, the start of embryogenesis requires specific histones. In Drosophila linker histone variant BigH1 is present in early embryos. To uncover the specific role of this alternative linker histone at early embryogenesis, we established fly lines in which domains of BigH1 have been replaced partially or completely with that of H1. Analysis of the resulting Drosophila lines revealed that at normal temperature somatic H1 can substitute the alternative linker histone, but at low temperature the globular and C-terminal domains of BigH1 are essential for embryogenesis. In the presence of BigH1 nucleosome stability increases and core histone incorporation into nucleosomes is more rapid, while nucleosome spacing is unchanged. Chromatin formation in the presence of BigH1 permits the fast-paced nuclear divisions of the early embryo. We propose a model which explains how this specific linker histone ensures the rapid nucleosome reassembly required during quick replication cycles at the start of embryogenesis.
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Affiliation(s)
- László Henn
- Institute of Biochemistry, Biological Research Centre of Szeged, Szeged H-6726, Hungary
| | - Anikó Szabó
- Institute of Biochemistry, Biological Research Centre of Szeged, Szeged H-6726, Hungary.,Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary.,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary
| | - László Imre
- Department of Biophysics and Cell Biology, University of Debrecen, Debrecen H-4032 Hungary
| | - Ádám Román
- Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary
| | - Andrea Ábrahám
- Institute of Biochemistry, Biological Research Centre of Szeged, Szeged H-6726, Hungary.,Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary.,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary
| | - Balázs Vedelek
- Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary
| | - Péter Nánási
- Department of Biophysics and Cell Biology, University of Debrecen, Debrecen H-4032 Hungary
| | - Imre M Boros
- Institute of Biochemistry, Biological Research Centre of Szeged, Szeged H-6726, Hungary.,Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, Szeged H-6726, Hungary
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6
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Nánási P, Imre L, Firouzi Niaki E, Bosire R, Mocsár G, Türk-Mázló A, Ausio J, Szabó G. Doxorubicin induces large-scale and differential H2A and H2B redistribution in live cells. PLoS One 2020; 15:e0231223. [PMID: 32298286 PMCID: PMC7162453 DOI: 10.1371/journal.pone.0231223] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/18/2020] [Indexed: 01/10/2023] Open
Abstract
We observed prominent effects of doxorubicin (Dox), an anthracycline widely used in anti-cancer therapy, on the aggregation and intracellular distribution of both partners of the H2A-H2B dimer, with marked differences between the two histones. Histone aggregation, assessed by Laser Scanning Cytometry via the retention of the aggregates in isolated nuclei, was observed in the case of H2A. The dominant effect of the anthracycline on H2B was its massive accumulation in the cytoplasm of the Jurkat leukemia cells concomitant with its disappearance from the nuclei, detected by confocal microscopy and mass spectrometry. A similar effect of the anthracycline was observed in primary human lymphoid cells, and also in monocyte-derived dendritic cells that harbor an unusually high amount of H2B in their cytoplasm even in the absence of Dox treatment. The nucleo-cytoplasmic translocation of H2B was not affected by inhibitors of major biochemical pathways or the nuclear export inhibitor leptomycin B, but it was completely diminished by PYR-41, an inhibitor with pleiotropic effects on protein degradation pathways. Dox and PYR-41 acted synergistically according to isobologram analyses of cytotoxicity. These large-scale effects were detected already at Dox concentrations that may be reached in the typical clinical settings, therefore they can contribute both to the anti-cancer mechanism and to the side-effects of this anthracycline.
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Affiliation(s)
- Péter Nánási
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
| | - László Imre
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
| | - Erfaneh Firouzi Niaki
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
| | - Rosevalentine Bosire
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
| | - Gábor Mocsár
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
| | - Anett Türk-Mázló
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Juan Ausio
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Gábor Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Doctoral School of Molecular Cell and Immune Biology, Debrecen, Hungary
- * E-mail:
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7
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Interactions of Cisplatin and Daunorubicin at the Chromatin Level. Sci Rep 2020; 10:1107. [PMID: 31980698 PMCID: PMC6981277 DOI: 10.1038/s41598-020-57702-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/19/2019] [Indexed: 01/08/2023] Open
Abstract
Unexpectedly, the widely used anticancer agents Cisplatin (Cis-Pt) and Daunorubicin (Dauno) exhibited cell type- and concentration-dependent synergy or antagonism in vitro. We attempted to interpret these effects in terms of the changes elicited by the drugs in the chromatin, the target held primarily responsible for the cytotoxicity of both agents. We measured the effect of Cis-Pt on the levels of Dauno in different cell compartments, the effect of Cis-Pt on Dauno-induced nucleosome eviction, and assessed the influence of Dauno on DNA platination in flow- and laser scanning cytometry as well as in laser ablation-inductively coupled plasma-mass spectrometry assays. We show that the two drugs antagonize each other through a decrease of interstrand crosslinks upon co-treatment with Dauno, and also via the diminished Dauno uptake in the presence of Cis-Pt, and both effects are observed already at low Dauno concentrations. At high Dauno concentrations synergy becomes dominant because histone eviction by Dauno intercalation into the DNA is enhanced in the presence of co-treatment with Cis-Pt. These interactions may have an impact on the efficacy of combination treatment protocols, considering the long retention time of DNA adducts formed by both agents.
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8
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The influence of monovalent and divalent metal cations on the stability of the DNA-protein interaction in the nucleosome core particle. ADVANCES IN QUANTUM CHEMISTRY 2020. [DOI: 10.1016/bs.aiq.2020.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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Sharma D, De Falco L, Padavattan S, Rao C, Geifman-Shochat S, Liu CF, Davey CA. PARP1 exhibits enhanced association and catalytic efficiency with γH2A.X-nucleosome. Nat Commun 2019; 10:5751. [PMID: 31848352 PMCID: PMC6917767 DOI: 10.1038/s41467-019-13641-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/18/2019] [Indexed: 12/12/2022] Open
Abstract
The poly(ADP-ribose) polymerase, PARP1, plays a key role in maintaining genomic integrity by detecting DNA damage and mediating repair. γH2A.X is the primary histone marker for DNA double-strand breaks and PARP1 localizes to H2A.X-enriched chromatin damage sites, but the basis for this association is not clear. We characterize the kinetics of PARP1 binding to a variety of nucleosomes harbouring DNA double-strand breaks, which reveal that PARP1 associates faster with (γ)H2A.X- versus H2A-nucleosomes, resulting in a higher affinity for the former, which is maximal for γH2A.X-nucleosome that is also the activator eliciting the greatest poly-ADP-ribosylation catalytic efficiency. The enhanced activities with γH2A.X-nucleosome coincide with increased accessibility of the DNA termini resulting from the H2A.X-Ser139 phosphorylation. Indeed, H2A- and (γ)H2A.X-nucleosomes have distinct stability characteristics, which are rationalized by mutational analysis and (γ)H2A.X-nucleosome core crystal structures. This suggests that the γH2A.X epigenetic marker directly facilitates DNA repair by stabilizing PARP1 association and promoting catalysis. The poly(ADP-ribose) polymerases play a key role in maintaining genomic integrity by detecting DNA damage and mediating repair. Here the authors characterize the kinetics of PARP1 binding to a variety of nucleosomes harbouring DNA double-strand breaks.
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Affiliation(s)
- Deepti Sharma
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Louis De Falco
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Sivaraman Padavattan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.,Department of Biophysics, National Institute of Mental Health and Neurosciences, Bangalore, 560029, India
| | - Chang Rao
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Susana Geifman-Shochat
- 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
| | - Chuan-Fa Liu
- 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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10
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Krajewski WA. "Direct" and "Indirect" Effects of Histone Modifications: Modulation of Sterical Bulk as a Novel Source of Functionality. Bioessays 2019; 42:e1900136. [PMID: 31805213 DOI: 10.1002/bies.201900136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/17/2019] [Indexed: 12/26/2022]
Abstract
The chromatin-regulatory principles of histone post-translational modifications (PTMs) are discussed with a focus on the potential alterations in chromatin functional state due to steric and mechanical constraints imposed by bulky histone modifications such as ubiquitin and SUMO. In the classical view, PTMs operate as recruitment platforms for histone "readers," and as determinants of chromatin array compaction. Alterations of histone charges by "small" chemical modifications (e.g., acetylation, phosphorylation) could regulate nucleosome spontaneous dynamics without globally affecting nucleosome structure. These fluctuations in nucleosome wrapping can be exploited by chromatin-processing machinery. In contrast, ubiquitin and SUMO are comparable in size to histones, and it seems logical that these PTMs could conflict with canonical nucleosome organization. An experimentally testable hypothesis that by adding sterical bulk these PTMs can robustly alter nucleosome primary structure is proposed. The model presented here stresses the diversity of mechanisms by which histone PTMs regulate chromatin dynamics, primary structure and, hence, functionality.
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Affiliation(s)
- Wladyslaw A Krajewski
- N. K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Vavilova str. 26, Moscow, 119334, Russia
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11
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Intercalation of small molecules into DNA in chromatin is primarily controlled by superhelical constraint. PLoS One 2019; 14:e0224936. [PMID: 31747397 PMCID: PMC6867626 DOI: 10.1371/journal.pone.0224936] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/30/2019] [Indexed: 12/22/2022] Open
Abstract
The restricted access of regulatory factors to their binding sites on DNA wrapped around the nucleosomes is generally interpreted in terms of molecular shielding exerted by nucleosomal structure and internucleosomal interactions. Binding of proteins to DNA often includes intercalation of hydrophobic amino acids into the DNA. To assess the role of constrained superhelicity in limiting these interactions, we studied the binding of small molecule intercalators to chromatin in close to native conditions by laser scanning cytometry. We demonstrate that the nucleosome-constrained superhelical configuration of DNA is the main barrier to intercalation. As a result, intercalating compounds are virtually excluded from the nucleosome-occupied regions of the chromatin. Binding of intercalators to extranucleosomal regions is limited to a smaller degree, in line with the existence of net supercoiling in the regions comprising linker and nucleosome free DNA. Its relaxation by inducing as few as a single nick per ~50 kb increases intercalation in the entire chromatin loop, demonstrating the possibility for long-distance effects of regulatory potential.
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12
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Demidov O, Aksenova V, Dasso M, Arnaoutov A. The cell nucleus. A study in Burgundy. Nucleus 2019; 10:213-217. [PMID: 31405317 PMCID: PMC6949021 DOI: 10.1080/19491034.2019.1649835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Wilhelm Bernhard’s revolutionary microscopy techniques helped him put forward the hypothesis of specialized compartmentalization of the nucleus. He also described for the first time the nuclear bodies and peri-chromatin fibrils, and demonstrated that these granules contain an RNA component. The tradition of biennial workshops, named after this great scientist, continues, and this year it took place in the heart of Burgundy, in Dijon, France (May 20–24, 2019, organized by INSERM UMR1231, UBFC), where well-fed participants emphasized the importance of viewing the cell nucleus as a hub of specialized colloidal compartments that orchestrate replication, transcription and nuclear transport.
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Affiliation(s)
- Oleg Demidov
- a INSERM UMR1231, Laboratory of Excellence LipSTIC, University of Burgundy Franche-Comté , Dijon , France.,b Insitutute of Cytology, Russian Academy of Sciences and Petrov Institute of Oncology , Saint-Petersburg , Russia
| | - Vasilisa Aksenova
- c Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH , Bethesda , MD , USA
| | - Mary Dasso
- c Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH , Bethesda , MD , USA
| | - Alexei Arnaoutov
- c Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH , Bethesda , MD , USA
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13
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Hegedüs É, Kókai E, Nánási P, Imre L, Halász L, Jossé R, Antunovics Z, Webb MR, El Hage A, Pommier Y, Székvölgyi L, Dombrádi V, Szabó G. Endogenous single-strand DNA breaks at RNA polymerase II promoters in Saccharomyces cerevisiae. Nucleic Acids Res 2019; 46:10649-10668. [PMID: 30445637 PMCID: PMC6237785 DOI: 10.1093/nar/gky743] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 08/16/2018] [Indexed: 12/12/2022] Open
Abstract
Molecular combing and gel electrophoretic studies revealed endogenous nicks with free 3'OH ends at ∼100 kb intervals in the genomic DNA (gDNA) of unperturbed and G1-synchronized Saccharomyces cerevisiae cells. Analysis of the distribution of endogenous nicks by Nick ChIP-chip indicated that these breaks accumulated at active RNA polymerase II (RNAP II) promoters, reminiscent of the promoter-proximal transient DNA breaks of higher eukaryotes. Similar periodicity of endogenous nicks was found within the ribosomal rDNA cluster, involving every ∼10th of the tandemly repeated 9.1 kb units of identical sequence. Nicks were mapped by Southern blotting to a few narrow regions within the affected units. Three of them were overlapping the RNAP II promoters, while the ARS-containing IGS2 region was spared of nicks. By using a highly sensitive reverse-Southwestern blot method to map free DNA ends with 3'OH, nicks were shown to be distinct from other known rDNA breaks and linked to the regulation of rDNA silencing. Nicks in rDNA and the rest of the genome were typically found at the ends of combed DNA molecules, occasionally together with R-loops, comprising a major pool of vulnerable sites that are connected with transcriptional regulation.
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Affiliation(s)
- Éva Hegedüs
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Endre Kókai
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter Nánási
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Imre
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Halász
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Rozenn Jossé
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (CCR-NCI), NIH, Bethesda, MD, USA
| | - Zsuzsa Antunovics
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | | | - Aziz El Hage
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (CCR-NCI), NIH, Bethesda, MD, USA
| | - Lóránt Székvölgyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Viktor Dombrádi
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gábor Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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