1
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Ivanov M, Posysoev M, Lyubartsev AP. Coarse-Grained Modeling Using Neural Networks Trained on Structural Data. J Chem Theory Comput 2023; 19:6704-6717. [PMID: 37712507 PMCID: PMC10569054 DOI: 10.1021/acs.jctc.3c00516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Indexed: 09/16/2023]
Abstract
We propose a method of bottom-up coarse-graining, in which interactions within a coarse-grained model are determined by an artificial neural network trained on structural data obtained from multiple atomistic simulations. The method uses ideas of the inverse Monte Carlo approach, relating changes in the neural network weights with changes in average structural properties, such as radial distribution functions. As a proof of concept, we demonstrate the method on a system interacting by a Lennard-Jones potential modeled by a simple linear network and a single-site coarse-grained model of methanol-water solutions. In the latter case, we implement a nonlinear neural network with intermediate layers trained by atomistic simulations carried out at different methanol concentrations. We show that such a network acts as a transferable potential at the coarse-grained resolution for a wide range of methanol concentrations, including those not included in the training set.
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Affiliation(s)
- Mikhail Ivanov
- Department of Materials and
Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Maksim Posysoev
- Department of Materials and
Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Alexander P. Lyubartsev
- Department of Materials and
Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
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2
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Shi D, Huang Y, Bai C. Studies of the Mechanism of Nucleosome Dynamics: A Review on Multifactorial Regulation from Computational and Experimental Cases. Polymers (Basel) 2023; 15:polym15071763. [PMID: 37050377 PMCID: PMC10096840 DOI: 10.3390/polym15071763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 04/05/2023] Open
Abstract
The nucleosome, which organizes the long coil of genomic DNA in a highly condensed, polymeric way, is thought to be the basic unit of chromosomal structure. As the most important protein–DNA complex, its structural and dynamic features have been successively revealed in recent years. However, its regulatory mechanism, which is modulated by multiple factors, still requires systemic discussion. This study summarizes the regulatory factors of the nucleosome’s dynamic features from the perspective of histone modification, DNA methylation, and the nucleosome-interacting factors (transcription factors and nucleosome-remodeling proteins and cations) and focuses on the research exploring the molecular mechanism through both computational and experimental approaches. The regulatory factors that affect the dynamic features of nucleosomes are also discussed in detail, such as unwrapping, wrapping, sliding, and stacking. Due to the complexity of the high-order topological structures of nucleosomes and the comprehensive effects of regulatory factors, the research on the functional modulation mechanism of nucleosomes has encountered great challenges. The integration of computational and experimental approaches, the construction of physical modes for nucleosomes, and the application of deep learning techniques will provide promising opportunities for further exploration.
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Affiliation(s)
- Danfeng Shi
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Yuxin Huang
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
| | - Chen Bai
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong (Shenzhen), Shenzhen 518172, China
- Chenzhu (MoMeD) Biotechnology Co., Ltd., Hangzhou 310005, China
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3
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Portillo-Ledesma S, Li Z, Schlick T. Genome modeling: From chromatin fibers to genes. Curr Opin Struct Biol 2023; 78:102506. [PMID: 36577295 PMCID: PMC9908845 DOI: 10.1016/j.sbi.2022.102506] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/01/2022] [Accepted: 11/06/2022] [Indexed: 12/27/2022]
Abstract
The intricacies of the 3D hierarchical organization of the genome have been approached by many creative modeling studies. The specific model/simulation technique combination defines and restricts the system and phenomena that can be investigated. We present the latest modeling developments and studies of the genome, involving models ranging from nucleosome systems and small polynucleosome arrays to chromatin fibers in the kb-range, chromosomes, and whole genomes, while emphasizing gene folding from first principles. Clever combinations allow the exploration of many interesting phenomena involved in gene regulation, such as nucleosome structure and dynamics, nucleosome-nucleosome stacking, polynucleosome array folding, protein regulation of chromatin architecture, mechanisms of gene folding, loop formation, compartmentalization, and structural transitions at the chromosome and genome levels. Gene-level modeling with full details on nucleosome positions, epigenetic factors, and protein binding, in particular, can in principle be scaled up to model chromosomes and cells to study fundamental biological regulation.
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Affiliation(s)
- Stephanie Portillo-Ledesma
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, 10003, NY, USA
| | - Zilong Li
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, 10003, NY, USA
| | - Tamar Schlick
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, 10003, NY, USA; Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, 10012, NY, USA; New York University-East China Normal University Center for Computational Chemistry, New York University Shanghai, Room 340, Geography Building, 3663 North Zhongshan Road, Shanghai, 200122, China; Simons Center for Computational Physical Chemistry, 24 Waverly Place, Silver Building, New York University, New York, 10003, NY, USA.
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4
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Williams MR, Xiaokang Y, Hathaway NA, Kireev D. A simulation model of heterochromatin formation at submolecular detail. iScience 2022; 25:104590. [PMID: 35800764 PMCID: PMC9254115 DOI: 10.1016/j.isci.2022.104590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/16/2021] [Accepted: 06/08/2022] [Indexed: 11/15/2022] Open
Abstract
Heterochromatin is a physical state of the chromatin fiber that maintains gene repression during cell development. Although evidence exists on molecular mechanisms involved in heterochromatin formation, a detailed structural mechanism of heterochromatin formation needs a better understanding. We made use of a simple Monte Carlo simulation model with explicit representation of key molecular events to observe molecular self-organization leading to heterochromatin formation. Our simulations provide a structural interpretation of several important traits of the heterochromatinization process. In particular, this study provides a depiction of how small amounts of HP1 are able to induce a highly condensed chromatin state through HP1 dimerization and bridging of sequence-remote nucleosomes. It also elucidates structural roots of a yet poorly understood phenomenon of a nondeterministic nature of heterochromatin formation and subsequent gene repression. Experimental chromatin in vivo assay provides an unbiased estimate of time scale of repressive response to a heterochromatin-triggering event.
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Affiliation(s)
- Michael R. Williams
- Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina, Chapel Hill, NC 27513, USA
| | - Yan Xiaokang
- Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina, Chapel Hill, NC 27513, USA
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, Chapel Hill, NC 27599, USA
| | - Nathaniel A. Hathaway
- Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina, Chapel Hill, NC 27513, USA
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, Chapel Hill, NC 27599, USA
| | - Dmitri Kireev
- Center for Integrative Chemical Biology and Drug Discovery, University of North Carolina, Chapel Hill, NC 27513, USA
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
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5
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Wang H, Yang J, Zhang Y, Qian J, Wang J. Reconstruct high-resolution 3D genome structures for diverse cell-types using FLAMINGO. Nat Commun 2022; 13:2645. [PMID: 35551182 PMCID: PMC9098643 DOI: 10.1038/s41467-022-30270-2] [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: 08/19/2021] [Accepted: 04/22/2022] [Indexed: 11/30/2022] Open
Abstract
High-resolution reconstruction of spatial chromosome organizations from chromatin contact maps is highly demanded, but is hindered by extensive pairwise constraints, substantial missing data, and limited resolution and cell-type availabilities. Here, we present FLAMINGO, a computational method that addresses these challenges by compressing inter-dependent Hi-C interactions to delineate the underlying low-rank structures in 3D space, based on the low-rank matrix completion technique. FLAMINGO successfully generates 5 kb- and 1 kb-resolution spatial conformations for all chromosomes in the human genome across multiple cell-types, the largest resources to date. Compared to other methods using various experimental metrics, FLAMINGO consistently demonstrates superior accuracy in recapitulating observed structures with raises in scalability by orders of magnitude. The reconstructed 3D structures efficiently facilitate discoveries of higher-order multi-way interactions, imply biological interpretations of long-range QTLs, reveal geometrical properties of chromatin, and provide high-resolution references to understand structural variabilities. Importantly, FLAMINGO achieves robust predictions against high rates of missing data and significantly boosts 3D structure resolutions. Moreover, FLAMINGO shows vigorous cross cell-type structure predictions that capture cell-type specific spatial configurations via integration of 1D epigenomic signals. FLAMINGO can be widely applied to large-scale chromatin contact maps and expand high-resolution spatial genome conformations for diverse cell-types. High-resolution reconstruction of spatial chromosome organisation is in demand. Here the authors report FLAMINGO, for reconstructing high-resolution 3D Genome Organisation from HiC data which they use to generate both 5 kb and 1 kb-resolution 3D chromosomal structures for the human genome.
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Affiliation(s)
- Hao Wang
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Jiaxin Yang
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Yu Zhang
- Center for Immunobiology, Department of Investigative Medicine, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, MI, 49007, USA
| | - Jianliang Qian
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Mathematics, Michigan State University, East Lansing, MI, 48824, USA.
| | - Jianrong Wang
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA.
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6
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Latham AP, Zhang B. On the stability and layered organization of protein-DNA condensates. Biophys J 2022; 121:1727-1737. [PMID: 35364104 PMCID: PMC9117872 DOI: 10.1016/j.bpj.2022.03.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/02/2021] [Accepted: 03/24/2022] [Indexed: 11/17/2022] Open
Abstract
Multi-component phase separation is emerging as a key mechanism for the formation of biological condensates that play essential roles in signal sensing and transcriptional regulation. The molecular factors that dictate these condensates' stability and spatial organization are not fully understood, and it remains challenging to predict their microstructures. Using a near-atomistic, chemically accurate force field, we studied the phase behavior of chromatin regulators that are crucial for heterochromatin organization and their interactions with DNA. Our computed phase diagrams recapitulated previous experimental findings on different proteins. They revealed a strong dependence of condensate stability on the protein-DNA mixing ratio as a result of balancing protein-protein interactions and charge neutralization. Notably, a layered organization was observed in condensates formed by mixing HP1, histone H1, and DNA. This layered organization may be of biological relevance, as it enables cooperative DNA packaging between the two chromatin regulators: histone H1 softens the DNA to facilitate the compaction induced by HP1 droplets. Our study supports near-atomistic models as a valuable tool for characterizing the structure and stability of biological condensates.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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7
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Zunke C, Bewerunge J, Platten F, Egelhaaf SU, Godec A. First-passage statistics of colloids on fractals: Theory and experimental realization. SCIENCE ADVANCES 2022; 8:eabk0627. [PMID: 35061533 PMCID: PMC8782457 DOI: 10.1126/sciadv.abk0627] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 11/29/2021] [Indexed: 05/30/2023]
Abstract
In nature and technology, particle dynamics frequently occur in complex environments, for example in restricted geometries or crowded media. These dynamics have often been modeled invoking a fractal structure of the medium although the fractal structure was only indirectly inferred through the dynamics. Moreover, systematic studies have not yet been performed. Here, colloidal particles moving in a laser speckle pattern are used as a model system. In this case, the experimental observations can be reliably traced to the fractal structure of the underlying medium with an adjustable fractal dimension. First-passage time statistics reveal that the particles explore the speckle in a self-similar, fractal manner at least over four decades in time and on length scales up to 20 times the particle radius. The requirements for fractal diffusion to be applicable are laid out, and methods to extract the fractal dimension are established.
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Affiliation(s)
- Christoph Zunke
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Jörg Bewerunge
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Florian Platten
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
- Institute of Biological Information Processing, Biomacromolecular Systems and Processes (IBI-4), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Stefan U. Egelhaaf
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Aljaž Godec
- Mathematical bioPhysics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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8
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Wei J, Tian H, Zhou R, Shao Y, Song F, Gao YQ. Topological Constraints with Optimal Length Promote the Formation of Chromosomal Territories at Weakened Degree of Phase Separation. J Phys Chem B 2021; 125:9092-9101. [PMID: 34351763 DOI: 10.1021/acs.jpcb.1c03523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is generally agreed that the nuclei of eukaryotic cells at interphase are partitioned into disjointed territories, with distinct regions occupied by certain chromosomes. However, the underlying mechanism for such territorialization is still under debate. Here we model chromosomes as coarse-grained block copolymers and to investigate the effect of loop domains (LDs) on the formation of compartments and territories based on dissipative particle dynamics. A critical length of LDs, which depends sensitively on the length of polymeric blocks, is obtained to minimize the degree of phase separation. This also applies to the two-polymer system: The critical length not only maximizes the degree of territorialization but also minimizes the degree of phase separation. Interestingly, by comparing with experimental data, we find the critical length for LDs and the corresponding length of blocks to be respectively very close to the mean length of topologically associating domains (TADs) and chromosomal segments with different densities of CpG islands for human chromosomes. The results indicate that topological constraints with optimal length can contribute to the formation of territories by weakening the degree of phase separation, which likely promotes the chromosomal flexibility in response to genetic regulations.
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Affiliation(s)
- Jiachen Wei
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,Shenzhen Bay Laboratory, 5F, No. 9 Duxue Road, Nanshan District, 518055 Shenzhen, Guangdong, China
| | - Hao Tian
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
| | - Rui Zhou
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
| | - Yingfeng Shao
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi Qin Gao
- Shenzhen Bay Laboratory, 5F, No. 9 Duxue Road, Nanshan District, 518055 Shenzhen, Guangdong, China.,Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China.,Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing 100871, China
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9
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Jerkovic I, Cavalli G. Understanding 3D genome organization by multidisciplinary methods. Nat Rev Mol Cell Biol 2021; 22:511-528. [PMID: 33953379 DOI: 10.1038/s41580-021-00362-w] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2021] [Indexed: 02/03/2023]
Abstract
Understanding how chromatin is folded in the nucleus is fundamental to understanding its function. Although 3D genome organization has been historically difficult to study owing to a lack of relevant methodologies, major technological breakthroughs in genome-wide mapping of chromatin contacts and advances in imaging technologies in the twenty-first century considerably improved our understanding of chromosome conformation and nuclear architecture. In this Review, we discuss methods of 3D genome organization analysis, including sequencing-based techniques, such as Hi-C and its derivatives, Micro-C, DamID and others; microscopy-based techniques, such as super-resolution imaging coupled with fluorescence in situ hybridization (FISH), multiplex FISH, in situ genome sequencing and live microscopy methods; and computational and modelling approaches. We describe the most commonly used techniques and their contribution to our current knowledge of nuclear architecture and, finally, we provide a perspective on up-and-coming methods that open possibilities for future major discoveries.
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Affiliation(s)
- Ivana Jerkovic
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS, University of Montpellier, Montpellier, France.
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10
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Lin X, Qi Y, Latham AP, Zhang B. Multiscale modeling of genome organization with maximum entropy optimization. J Chem Phys 2021; 155:010901. [PMID: 34241389 PMCID: PMC8253599 DOI: 10.1063/5.0044150] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/28/2021] [Indexed: 12/15/2022] Open
Abstract
Three-dimensional (3D) organization of the human genome plays an essential role in all DNA-templated processes, including gene transcription, gene regulation, and DNA replication. Computational modeling can be an effective way of building high-resolution genome structures and improving our understanding of these molecular processes. However, it faces significant challenges as the human genome consists of over 6 × 109 base pairs, a system size that exceeds the capacity of traditional modeling approaches. In this perspective, we review the progress that has been made in modeling the human genome. Coarse-grained models parameterized to reproduce experimental data via the maximum entropy optimization algorithm serve as effective means to study genome organization at various length scales. They have provided insight into the principles of whole-genome organization and enabled de novo predictions of chromosome structures from epigenetic modifications. Applications of these models at a near-atomistic resolution further revealed physicochemical interactions that drive the phase separation of disordered proteins and dictate chromatin stability in situ. We conclude with an outlook on the opportunities and challenges in studying chromosome dynamics.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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11
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Nitsch S, Zorro Shahidian L, Schneider R. Histone acylations and chromatin dynamics: concepts, challenges, and links to metabolism. EMBO Rep 2021. [PMID: 34159701 DOI: 10.5252/embr.202152774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023] Open
Abstract
In eukaryotic cells, DNA is tightly packed with the help of histone proteins into chromatin. Chromatin architecture can be modified by various post-translational modifications of histone proteins. For almost 60 years now, studies on histone lysine acetylation have unraveled the contribution of this acylation to an open chromatin state with increased DNA accessibility, permissive for gene expression. Additional complexity emerged from the discovery of other types of histone lysine acylations. The acyl group donors are products of cellular metabolism, and distinct histone acylations can link the metabolic state of a cell with chromatin architecture and contribute to cellular adaptation through changes in gene expression. Currently, various technical challenges limit our full understanding of the actual impact of most histone acylations on chromatin dynamics and of their biological relevance. In this review, we summarize the state of the art and provide an overview of approaches to overcome these challenges. We further discuss the concept of subnuclear metabolic niches that could regulate local CoA availability and thus couple cellular metabolisms with the epigenome.
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Affiliation(s)
- Sandra Nitsch
- Institute of Functional Epigenetics (IFE), Helmholtz Zentrum München, Neuherberg, Germany
| | - Lara Zorro Shahidian
- Institute of Functional Epigenetics (IFE), Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), University of Cantabria, Santander, Spain
| | - Robert Schneider
- Institute of Functional Epigenetics (IFE), Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Faculty of Biology, Ludwig-Maximilians Universität München, Planegg-Martinsried, Germany
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12
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Nitsch S, Zorro Shahidian L, Schneider R. Histone acylations and chromatin dynamics: concepts, challenges, and links to metabolism. EMBO Rep 2021; 22:e52774. [PMID: 34159701 PMCID: PMC8406397 DOI: 10.15252/embr.202152774] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/08/2021] [Accepted: 05/31/2021] [Indexed: 01/17/2023] Open
Abstract
In eukaryotic cells, DNA is tightly packed with the help of histone proteins into chromatin. Chromatin architecture can be modified by various post-translational modifications of histone proteins. For almost 60 years now, studies on histone lysine acetylation have unraveled the contribution of this acylation to an open chromatin state with increased DNA accessibility, permissive for gene expression. Additional complexity emerged from the discovery of other types of histone lysine acylations. The acyl group donors are products of cellular metabolism, and distinct histone acylations can link the metabolic state of a cell with chromatin architecture and contribute to cellular adaptation through changes in gene expression. Currently, various technical challenges limit our full understanding of the actual impact of most histone acylations on chromatin dynamics and of their biological relevance. In this review, we summarize the state of the art and provide an overview of approaches to overcome these challenges. We further discuss the concept of subnuclear metabolic niches that could regulate local CoA availability and thus couple cellular metabolisms with the epigenome.
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Affiliation(s)
- Sandra Nitsch
- Institute of Functional Epigenetics (IFE)Helmholtz Zentrum MünchenNeuherbergGermany
| | - Lara Zorro Shahidian
- Institute of Functional Epigenetics (IFE)Helmholtz Zentrum MünchenNeuherbergGermany
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC)University of CantabriaSantanderSpain
| | - Robert Schneider
- Institute of Functional Epigenetics (IFE)Helmholtz Zentrum MünchenNeuherbergGermany
- German Center for Diabetes Research (DZD)NeuherbergGermany
- Faculty of BiologyLudwig‐Maximilians Universität MünchenPlanegg‐MartinsriedGermany
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13
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Farr SE, Woods EJ, Joseph JA, Garaizar A, Collepardo-Guevara R. Nucleosome plasticity is a critical element of chromatin liquid-liquid phase separation and multivalent nucleosome interactions. Nat Commun 2021; 12:2883. [PMID: 34001913 PMCID: PMC8129070 DOI: 10.1038/s41467-021-23090-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/23/2021] [Indexed: 12/19/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) is an important mechanism that helps explain the membraneless compartmentalization of the nucleus. Because chromatin compaction and LLPS are collective phenomena, linking their modulation to the physicochemical features of nucleosomes is challenging. Here, we develop an advanced multiscale chromatin model-integrating atomistic representations, a chemically-specific coarse-grained model, and a minimal model-to resolve individual nucleosomes within sub-Mb chromatin domains and phase-separated systems. To overcome the difficulty of sampling chromatin at high resolution, we devise a transferable enhanced-sampling Debye-length replica-exchange molecular dynamics approach. We find that nucleosome thermal fluctuations become significant at physiological salt concentrations and destabilize the 30-nm fiber. Our simulations show that nucleosome breathing favors stochastic folding of chromatin and promotes LLPS by simultaneously boosting the transient nature and heterogeneity of nucleosome-nucleosome contacts, and the effective nucleosome valency. Our work puts forward the intrinsic plasticity of nucleosomes as a key element in the liquid-like behavior of nucleosomes within chromatin, and the regulation of chromatin LLPS.
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Affiliation(s)
- Stephen E Farr
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Esmae J Woods
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Jerelle A Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
- Department of Genetics, University of Cambridge, Cambridge, UK.
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14
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Jooß K, Schachner LF, Watson R, Gillespie ZB, Howard SA, Cheek MA, Meiners MJ, Sobh A, Licht JD, Keogh MC, Kelleher NL. Separation and Characterization of Endogenous Nucleosomes by Native Capillary Zone Electrophoresis-Top-Down Mass Spectrometry. Anal Chem 2021; 93:5151-5160. [PMID: 33749242 PMCID: PMC8040852 DOI: 10.1021/acs.analchem.0c04975] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We report a novel platform [native capillary zone electrophoresis-top-down mass spectrometry (nCZE-TDMS)] for the separation and characterization of whole nucleosomes, their histone subunits, and post-translational modifications (PTMs). As the repeating unit of chromatin, mononucleosomes (Nucs) are an ∼200 kDa complex of DNA and histone proteins involved in the regulation of key cellular processes central to human health and disease. Unraveling the covalent modification landscape of histones and their defined stoichiometries within Nucs helps to explain epigenetic regulatory mechanisms. In nCZE-TDMS, online Nuc separation is followed by a three-tier tandem MS approach that measures the intact mass of Nucs, ejects and detects the constituent histones, and fragments to sequence the histone. The new platform was optimized with synthetic Nucs to significantly reduce both sample requirements and cost compared to direct infusion. Limits of detection were in the low-attomole range, with linearity of over ∼3 orders of magnitude. The nCZE-TDMS platform was applied to endogenous Nucs from two cell lines distinguished by overexpression or knockout of histone methyltransferase NSD2/MMSET, where analysis of constituent histones revealed changes in histone abundances over the course of the CZE separation. We are confident the nCZE-TDMS platform will help advance nucleosome-level research in the fields of chromatin and epigenetics.
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Affiliation(s)
- Kevin Jooß
- Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Luis F Schachner
- Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Rachel Watson
- EpiCypher Incorporated, Durham, North Carolina 27709, United States
| | | | - Sarah A Howard
- EpiCypher Incorporated, Durham, North Carolina 27709, United States
| | - Marcus A Cheek
- EpiCypher Incorporated, Durham, North Carolina 27709, United States
| | | | - Amin Sobh
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida 32610, United States
| | - Jonathan D Licht
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, Florida 32610, United States
| | | | - Neil L Kelleher
- Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, United States
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15
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Decoding the protein composition of whole nucleosomes with Nuc-MS. Nat Methods 2021; 18:303-308. [PMID: 33589837 PMCID: PMC7954958 DOI: 10.1038/s41592-020-01052-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 12/21/2020] [Indexed: 01/30/2023]
Abstract
Current proteomic approaches disassemble and digest nucleosome particles, blurring readouts of the 'histone code'. To preserve nucleosome-level information, we developed Nuc-MS, which displays the landscape of histone variants and their post-translational modifications (PTMs) in a single mass spectrum. Combined with immunoprecipitation, Nuc-MS quantified nucleosome co-occupancy of histone H3.3 with variant H2A.Z (sixfold over bulk) and the co-occurrence of oncogenic H3.3K27M with euchromatic marks (for example, a >15-fold enrichment of dimethylated H3K79me2). Nuc-MS is highly concordant with chromatin immunoprecipitation-sequencing (ChIP-seq) and offers a new readout of nucleosome-level biology.
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16
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Kohestani H, Wereszczynski J. Effects of H2A.B incorporation on nucleosome structures and dynamics. Biophys J 2021; 120:1498-1509. [PMID: 33609493 DOI: 10.1016/j.bpj.2021.01.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 12/31/2020] [Accepted: 01/12/2021] [Indexed: 01/20/2023] Open
Abstract
The H2A.B histone variant is an epigenetic regulator involved in transcriptional upregulation, DNA synthesis, and splicing that functions by replacing the canonical H2A histone in the nucleosome core particle. Introduction of H2A.B results in less compact nucleosome states with increased DNA unwinding and accessibility at the nucleosomal entry and exit sites. Despite being well characterized experimentally, the molecular mechanisms by which H2A.B incorporation alters nucleosome stability and dynamics remain poorly understood. To study the molecular mechanisms of H2A.B, we have performed a series of conventional and enhanced sampling molecular dynamics simulation of H2A.B- and canonical H2A-containing nucleosomes. Results of conventional simulations show that H2A.B weakens protein-protein and protein-DNA interactions at specific locations throughout the nucleosome. These weakened interactions result in significantly more DNA opening from both the entry and exit sites in enhanced sampling simulations. Furthermore, free energy profiles show that H2A.B-containing nucleosomes have significantly broader free wells and that H2A.B allows for sampling of states with increased DNA breathing, which are shown to be stable on the hundreds of nanoseconds timescale with further conventional simulations. Together, our results show the molecular mechanisms by which H2A.B creates less compacted nucleosome states as a means of increasing genetic accessibility and gene transcription.
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Affiliation(s)
- Havva Kohestani
- Department of Biology, Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois
| | - Jeff Wereszczynski
- Department of Physics, Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois.
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17
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Ding X, Lin X, Zhang B. Stability and folding pathways of tetra-nucleosome from six-dimensional free energy surface. Nat Commun 2021; 12:1091. [PMID: 33597548 PMCID: PMC7889939 DOI: 10.1038/s41467-021-21377-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 01/22/2021] [Indexed: 01/01/2023] Open
Abstract
The three-dimensional organization of chromatin is expected to play critical roles in regulating genome functions. High-resolution characterization of its structure and dynamics could improve our understanding of gene regulation mechanisms but has remained challenging. Using a near-atomistic model that preserves the chemical specificity of protein-DNA interactions at residue and base-pair resolution, we studied the stability and folding pathways of a tetra-nucleosome. Dynamical simulations performed with an advanced sampling technique uncovered multiple pathways that connect open chromatin configurations with the zigzag crystal structure. Intermediate states along the simulated folding pathways resemble chromatin configurations reported from in situ experiments. We further determined a six-dimensional free energy surface as a function of the inter-nucleosome distances via a deep learning approach. The zigzag structure can indeed be seen as the global minimum of the surface. However, it is not favored by a significant amount relative to the partially unfolded, in situ configurations. Chemical perturbations such as histone H4 tail acetylation and thermal fluctuations can further tilt the energetic balance to stabilize intermediate states. Our study provides insight into the connection between various reported chromatin configurations and has implications on the in situ relevance of the 30 nm fiber. The three-dimensional organization of chromatin plays critical roles in regulating genome function. Here the authors apply a near atomistic model to study the structure and dynamics of the chromatin folding unit - the tetra-nucleosome - to provide insight into how chromatin folds.
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Affiliation(s)
- Xinqiang Ding
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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18
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Huertas J, Cojocaru V. Breaths, Twists, and Turns of Atomistic Nucleosomes. J Mol Biol 2020; 433:166744. [PMID: 33309853 DOI: 10.1016/j.jmb.2020.166744] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/02/2020] [Accepted: 12/02/2020] [Indexed: 02/07/2023]
Abstract
Gene regulation programs establish cellular identity and rely on dynamic changes in the structural packaging of genomic DNA. The DNA is packaged in chromatin, which is formed from arrays of nucleosomes displaying different degree of compaction and different lengths of inter-nucleosomal linker DNA. The nucleosome represents the repetitive unit of chromatin and is formed by wrapping 145-147 basepairs of DNA around an octamer of histone proteins. Each of the four histones is present twice and has a structured core and intrinsically disordered terminal tails. Chromatin dynamics are triggered by inter- and intra-nucleosome motions that are controlled by the DNA sequence, the interactions between the histone core and the DNA, and the conformations, positions, and DNA interactions of the histone tails. Understanding chromatin dynamics requires studying all these features at the highest possible resolution. For this, molecular dynamics simulations can be used as a powerful complement or alternative to experimental approaches, from which it is often very challenging to characterize the structural features and atomic interactions controlling nucleosome motions. Molecular dynamics simulations can be performed at different resolutions, by coarse graining the molecular system with varying levels of details. Here we review the successes and the remaining challenges of the application of atomic resolution simulations to study the structure and dynamics of nucleosomes and their complexes with interacting partners.
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Affiliation(s)
- Jan Huertas
- In Silico Biomolecular Structure and Dynamics Group, Hubrecht Institute, Utrecht, the Netherlands; Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany
| | - Vlad Cojocaru
- In Silico Biomolecular Structure and Dynamics Group, Hubrecht Institute, Utrecht, the Netherlands; Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany.
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19
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Melters DP, Dalal Y. Nano-Surveillance: Tracking Individual Molecules in a Sea of Chromatin. J Mol Biol 2020; 433:166720. [PMID: 33221335 PMCID: PMC8770095 DOI: 10.1016/j.jmb.2020.11.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/06/2020] [Accepted: 11/16/2020] [Indexed: 01/12/2023]
Abstract
Chromatin is the epigenomic platform for diverse nuclear processes such as DNA repair, replication, transcription, telomere, and centromere function. In cancer cells, mutations in key processes result in DNA amplification, chromosome translocations, and chromothripsis, severely distorting the natural chromatin state. In normal and diseased states, dozens of chromatin effectors alter the physical integrity and dynamics of chromatin at the level of both single nucleosomes and arrays of nucleosomes folded into 3-dimensional shapes. Integrating these length scales, from the 10 nm sized nucleosome to mitotic chromosomes, whilst jostling within the crowded environment of the cell, cannot yet be achieved by a single technology. In this review, we discuss tools that have proven powerful in the investigation of nucleosome and chromatin fiber dynamics. We also provide a deeper focus into atomic force microscopy (AFM) applications that can bridge diverse length and time scales. Using time course AFM, we observe that chromatin condensation by H1.5 is dynamic, whereas using nano-indentation force spectroscopy we observe that both histone variants and nucleosome binding partners alter material properties of individual nucleosomes. Finally, we demonstrate how high-speed AFM can visualize plasmid DNA dynamics, intermittent nucleosome-nucleosome contacts, and changes in nucleosome phasing along a contiguous chromatin fiber. Altogether, the development of innovative technologies holds the promise of revealing the secret lives of nucleosomes, potentially bridging the gaps in our understanding of how chromatin works within living cells and tissues.
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Affiliation(s)
- Daniël P Melters
- National Cancer Institute, Center for Cancer Research, Laboratory of Receptor Biology and Gene Expression, Bethesda, MD, United States.
| | - Yamini Dalal
- National Cancer Institute, Center for Cancer Research, Laboratory of Receptor Biology and Gene Expression, Bethesda, MD, United States.
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20
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Johnstone CP, Wang NB, Sevier SA, Galloway KE. Understanding and Engineering Chromatin as a Dynamical System across Length and Timescales. Cell Syst 2020; 11:424-448. [PMID: 33212016 DOI: 10.1016/j.cels.2020.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/22/2020] [Accepted: 09/29/2020] [Indexed: 12/20/2022]
Abstract
Connecting the molecular structure and function of chromatin across length and timescales remains a grand challenge to understanding and engineering cellular behaviors. Across five orders of magnitude, dynamic processes constantly reshape chromatin structures, driving spaciotemporal patterns of gene expression and cell fate. Through the interplay of structure and function, the genome operates as a highly dynamic feedback control system. Recent experimental techniques have provided increasingly detailed data that revise and augment the relatively static, hierarchical view of genomic architecture with an understanding of how dynamic processes drive organization. Here, we review how novel technologies from sequencing, imaging, and synthetic biology refine our understanding of chromatin structure and function and enable chromatin engineering. Finally, we discuss opportunities to use these tools to enhance understanding of the dynamic interrelationship of chromatin structure and function.
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Affiliation(s)
| | - Nathan B Wang
- Department of Chemical Engineering, MIT, 25 Ames St., Cambridge, MA 02139, USA
| | - Stuart A Sevier
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA; Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA, USA.
| | - Kate E Galloway
- Department of Chemical Engineering, MIT, 25 Ames St., Cambridge, MA 02139, USA.
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21
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Schlick T. Multiscale Genome Organization: Dazzling Subject and Inventive Methods. Biophys J 2020; 118:E1-E3. [PMID: 32305070 PMCID: PMC7161524 DOI: 10.1016/j.bpj.2020.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 01/20/2023] Open
Affiliation(s)
- Tamar Schlick
- Department of Chemistry, Courant Institute of Mathematical Sciences, New York University, New York, New York.
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