1
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Kobayashi W, Sappler AH, Bollschweiler D, Kümmecke M, Basquin J, Arslantas EN, Ruangroengkulrith S, Hornberger R, Duderstadt K, Tachibana K. Nucleosome-bound NR5A2 structure reveals pioneer factor mechanism by DNA minor groove anchor competition. Nat Struct Mol Biol 2024; 31:757-766. [PMID: 38409506 PMCID: PMC11102866 DOI: 10.1038/s41594-024-01239-0] [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: 06/02/2023] [Accepted: 01/31/2024] [Indexed: 02/28/2024]
Abstract
Gene expression during natural and induced reprogramming is controlled by pioneer transcription factors that initiate transcription from closed chromatin. Nr5a2 is a key pioneer factor that regulates zygotic genome activation in totipotent embryos, pluripotency in embryonic stem cells and metabolism in adult tissues, but the mechanism of its pioneer activity remains poorly understood. Here, we present a cryo-electron microscopy structure of human NR5A2 bound to a nucleosome. The structure shows that the conserved carboxy-terminal extension (CTE) loop of the NR5A2 DNA-binding domain competes with a DNA minor groove anchor of the nucleosome and releases entry-exit site DNA. Mutational analysis showed that NR5A2 D159 of the CTE is dispensable for DNA binding but required for stable nucleosome association and persistent DNA 'unwrapping'. These findings suggest that NR5A2 belongs to an emerging class of pioneer factors that can use DNA minor groove anchor competition to destabilize nucleosomes and facilitate gene expression during reprogramming.
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Affiliation(s)
- Wataru Kobayashi
- Department of Totipotency, Max Planck Institute of Biochemistry (MPIB), Munich, Germany
| | - Anna H Sappler
- Structure and Dynamics of Molecular Machines, MPIB, Munich, Germany
| | | | - Maximilian Kümmecke
- Department of Totipotency, Max Planck Institute of Biochemistry (MPIB), Munich, Germany
| | - Jérôme Basquin
- Department of Structural Cell Biology, Crystallization Facility, MPIB, Munich, Germany
| | - Eda Nur Arslantas
- Department of Totipotency, Max Planck Institute of Biochemistry (MPIB), Munich, Germany
| | | | - Renate Hornberger
- Department of Totipotency, Max Planck Institute of Biochemistry (MPIB), Munich, Germany
| | - Karl Duderstadt
- Structure and Dynamics of Molecular Machines, MPIB, Munich, Germany
- Department of Bioscience, Technical University of Munich, Garching, Germany
| | - Kikuë Tachibana
- Department of Totipotency, Max Planck Institute of Biochemistry (MPIB), Munich, Germany.
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2
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Lian T, Guan R, Zhou BR, Bai Y. Structural mechanism of synergistic targeting of the CX3CR1 nucleosome by PU.1 and C/EBPα. Nat Struct Mol Biol 2024; 31:633-643. [PMID: 38267599 DOI: 10.1038/s41594-023-01189-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 11/23/2023] [Indexed: 01/26/2024]
Abstract
Pioneer transcription factors are vital for cell fate changes. PU.1 and C/EBPα work together to regulate hematopoietic stem cell differentiation. However, how they recognize in vivo nucleosomal DNA targets remains elusive. Here we report the structures of the nucleosome containing the mouse genomic CX3CR1 enhancer DNA and its complexes with PU.1 alone and with both PU.1 and the C/EBPα DNA binding domain. Our structures reveal that PU.1 binds the DNA motif at the exit linker, shifting 17 bp of DNA into the core region through interactions with H2A, unwrapping ~20 bp of nucleosomal DNA. C/EBPα binding, aided by PU.1's repositioning, unwraps ~25 bp of entry DNA. The PU.1 Q218H mutation, linked to acute myeloid leukemia, disrupts PU.1-H2A interactions. PU.1 and C/EBPα jointly displace linker histone H1 and open the H1-condensed nucleosome array. Our study unveils how two pioneer factors can work cooperatively to open closed chromatin by altering DNA positioning in the nucleosome.
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Affiliation(s)
- Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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3
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Onoa B, Díaz-Celis C, Cañari-Chumpitaz C, Lee A, Bustamante C. Real-Time Multistep Asymmetrical Disassembly of Nucleosomes and Chromatosomes Visualized by High-Speed Atomic Force Microscopy. ACS CENTRAL SCIENCE 2024; 10:122-137. [PMID: 38292612 PMCID: PMC10823521 DOI: 10.1021/acscentsci.3c00735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 10/30/2023] [Accepted: 11/30/2023] [Indexed: 02/01/2024]
Abstract
During replication, expression, and repair of the eukaryotic genome, cellular machinery must access the DNA wrapped around histone proteins forming nucleosomes. These octameric protein·DNA complexes are modular, dynamic, and flexible and unwrap or disassemble either spontaneously or by the action of molecular motors. Thus, the mechanism of formation and regulation of subnucleosomal intermediates has gained attention genome-wide because it controls DNA accessibility. Here, we imaged nucleosomes and their more compacted structure with the linker histone H1 (chromatosomes) using high-speed atomic force microscopy to visualize simultaneously the changes in the DNA and the histone core during their disassembly when deposited on mica. Furthermore, we trained a neural network and developed an automatic algorithm to track molecular structural changes in real time. Our results show that nucleosome disassembly is a sequential process involving asymmetrical stepwise dimer ejection events. The presence of H1 restricts DNA unwrapping, significantly increases the nucleosomal lifetime, and affects the pathway in which heterodimer asymmetrical dissociation occurs. We observe that tetrasomes are resilient to disassembly and that the tetramer core (H3·H4)2 can diffuse along the nucleosome positioning sequence. Tetrasome mobility might be critical to the proper assembly of nucleosomes and can be relevant during nucleosomal transcription, as tetrasomes survive RNA polymerase passage. These findings are relevant to understanding nucleosome intrinsic dynamics and their modification by DNA-processing enzymes.
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Affiliation(s)
- Bibiana Onoa
- Jason
L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of
California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences, QB3, University of California, Berkeley, California 94720, United States
| | - César Díaz-Celis
- Jason
L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of
California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences, QB3, University of California, Berkeley, California 94720, United States
| | - Cristhian Cañari-Chumpitaz
- Jason
L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of
California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences, QB3, University of California, Berkeley, California 94720, United States
| | - Antony Lee
- Laboratoire
Photonique Numérique et Nanosciences, LP2N UMR 5298, Université de Bordeaux, Institut d’Optique,
CNRS, F-33400 Talence, France
| | - Carlos Bustamante
- Jason
L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, California 94720, United States
- Howard
Hughes Medical Institute, University of
California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences, QB3, University of California, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute, University
of California, Berkeley, California 94720, United States
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4
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Lian T, Guan R, Zhou BR, Bai Y. Structural mechanism of synergistic targeting of the CX3CR1 nucleosome by PU.1 and C/EBPα. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554718. [PMID: 37790476 PMCID: PMC10542146 DOI: 10.1101/2023.08.25.554718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Pioneer transcription factors are vital for cell fate changes. PU.1 and C/EBPα work together to regulate hematopoietic stem cell differentiation. However, how they recognize in vivo nucleosomal DNA targets remain elusive. Here we report the structures of the nucleosome containing the mouse genomic CX3CR1 enhancer DNA and its complexes with PU.1 alone and with both PU.1 and the C/EBPα DNA binding domain. Our structures reveal that PU.1 binds the DNA motif at the exit linker, shifting 17 bp of DNA into the core region through interactions with H2A, unwrapping ~20 bp of nucleosomal DNA. C/EBPα binding, aided by PU.1's repositioning, unwraps ~25 bp entry DNA. The PU.1 Q218H mutation, linked to acute myeloid leukemia, disrupts PU.1-H2A interactions. PU.1 and C/EBPα jointly displace linker histone H1 and open the H1-condensed nucleosome array. Our study unveils how two pioneer factors can work cooperatively to open closed chromatin by altering DNA positioning in the nucleosome.
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Affiliation(s)
- Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- These authors equally contributed to this work
| | - Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- These authors equally contributed to this work
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular 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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5
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Are extraordinary nucleosome structures more ordinary than we thought? Chromosoma 2023:10.1007/s00412-023-00791-w. [PMID: 36917245 DOI: 10.1007/s00412-023-00791-w] [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: 01/23/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/16/2023]
Abstract
The nucleosome is a DNA-protein assembly that is the basic unit of chromatin. A nucleosome can adopt various structures. In the canonical nucleosome structure, 145-147 bp of DNA is wrapped around a histone heterooctamer. The strong histone-DNA interactions cause the DNA to be inaccessible for nuclear processes such as transcription. Therefore, the canonical nucleosome structure has to be altered into different, non-canonical structures to increase DNA accessibility. While it is recognised that non-canonical structures do exist, these structures are not well understood. In this review, we discuss both the evidence for various non-canonical nucleosome structures in the nucleus and the factors that are believed to induce these structures. The wide range of non-canonical structures is likely to regulate the amount of accessible DNA, and thus have important nuclear functions.
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6
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Morioka S, Sato S, Horikoshi N, Kujirai T, Tomita T, Baba Y, Kakuta T, Ogoshi T, Puppulin L, Sumino A, Umeda K, Kodera N, Kurumizaka H, Shibata M. High-Speed Atomic Force Microscopy Reveals Spontaneous Nucleosome Sliding of H2A.Z at the Subsecond Time Scale. NANO LETTERS 2023; 23:1696-1704. [PMID: 36779562 DOI: 10.1021/acs.nanolett.2c04346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nucleosome dynamics, such as nucleosome sliding and DNA unwrapping, are important for gene regulation in eukaryotic chromatin. H2A.Z, a variant of histone H2A that is highly evolutionarily conserved, participates in gene regulation by forming unstable multipositioned nucleosomes in vivo and in vitro. However, the subsecond dynamics of this unstable nucleosome have not been directly visualized under physiological conditions. Here, we used high-speed atomic force microscopy (HS-AFM) to directly visualize the subsecond dynamics of human H2A.Z.1-nucleosomes. HS-AFM videos show nucleosome sliding along 4 nm of DNA within 0.3 s in any direction. This sliding was also visualized in an H2A.Z.1 mutant, in which the C-terminal half was replaced by the corresponding canonical H2A amino acids, indicating that the interaction between the N-terminal region of H2A.Z.1 and the DNA is responsible for nucleosome sliding. These results may reveal the relationship between nucleosome dynamics and gene regulation by histone H2A.Z.
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Affiliation(s)
- Shin Morioka
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Shoko Sato
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Naoki Horikoshi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takuya Tomita
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Yudai Baba
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Takahiro Kakuta
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Tomoki Ogoshi
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Leonardo Puppulin
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Ayumi Sumino
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Kenichi Umeda
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Noriyuki Kodera
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Mikihiro Shibata
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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7
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Takizawa Y, Kurumizaka H. Chromatin structure meets cryo-EM: Dynamic building blocks of the functional architecture. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2022; 1865:194851. [PMID: 35952957 DOI: 10.1016/j.bbagrm.2022.194851] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/04/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Chromatin is a dynamic molecular complex composed of DNA and proteins that package the DNA in the nucleus of eukaryotic cells. The basic structural unit of chromatin is the nucleosome core particle, composed of ~150 base pairs of genomic DNA wrapped around a histone octamer containing two copies each of four histones, H2A, H2B, H3, and H4. Individual nucleosome core particles are connected by short linker DNAs, forming a nucleosome array known as a beads-on-a-string fiber. Higher-order structures of chromatin are closely linked to nuclear events such as replication, transcription, recombination, and repair. Recently, a variety of chromatin structures have been determined by single-particle cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET), and their structural details have provided clues about the chromatin architecture functions in the cell. In this review, we highlight recent cryo-EM structural studies of a fundamental chromatin unit to clarify the functions of chromatin.
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Affiliation(s)
- Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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8
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MacCarthy CM, Huertas J, Ortmeier C, Vom Bruch H, Tan DS, Reinke D, Sander A, Bergbrede T, Jauch R, Schöler HR, Cojocaru V. OCT4 interprets and enhances nucleosome flexibility. Nucleic Acids Res 2022; 50:10311-10327. [PMID: 36130732 PMCID: PMC9561370 DOI: 10.1093/nar/gkac755] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 07/28/2022] [Accepted: 08/24/2022] [Indexed: 01/06/2023] Open
Abstract
Pioneer transcription factors are proteins that induce cellular identity transitions by binding to inaccessible regions of DNA in nuclear chromatin. They contribute to chromatin opening and recruit other factors to regulatory DNA elements. The structural features and dynamics modulating their interaction with nucleosomes are still unresolved. From a combination of experiments and molecular simulations, we reveal here how the pioneer factor and master regulator of pluripotency, Oct4, interprets and enhances nucleosome structural flexibility. The magnitude of Oct4’s impact on nucleosome dynamics depends on the binding site position and the mobility of the unstructured tails of nucleosomal histone proteins. Oct4 uses both its DNA binding domains to propagate and stabilize open nucleosome conformations, one for specific sequence recognition and the other for nonspecific interactions with nearby regions of DNA. Our findings provide a structural basis for the versatility of transcription factors in engaging with nucleosomes and have implications for understanding how pioneer factors induce chromatin dynamics.
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Affiliation(s)
- Caitlin M MacCarthy
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Jan Huertas
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Yusuf Hamied Department of Chemistry, University of Cambridge, UK
| | - Claudia Ortmeier
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Hermann Vom Bruch
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Daisylyn Senna Tan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Deike Reinke
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Astrid Sander
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Ralf Jauch
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Hans R Schöler
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Medical Faculty, University of Münster, Germany
| | - Vlad Cojocaru
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Computational Structural Biology Group, University of Utrecht, The Netherlands.,STAR-UBB Institute, Babeş-Bolyai University, Cluj-Napoca, Romania
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9
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Xu Y, Dang S. Recent Technical Advances in Sample Preparation for Single-Particle Cryo-EM. Front Mol Biosci 2022; 9:892459. [PMID: 35813814 PMCID: PMC9263182 DOI: 10.3389/fmolb.2022.892459] [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: 03/09/2022] [Accepted: 05/12/2022] [Indexed: 11/25/2022] Open
Abstract
Cryo-sample preparation is a vital step in the process of obtaining high-resolution structures of macromolecules by using the single-particle cryo–electron microscopy (cryo-EM) method; however, cryo-sample preparation is commonly hampered by high uncertainty and low reproducibility. Specifically, the existence of air-water interfaces during the sample vitrification process could cause protein denaturation and aggregation, complex disassembly, adoption of preferred orientations, and other serious problems affecting the protein particles, thereby making it challenging to pursue high-resolution 3D reconstruction. Therefore, sample preparation has emerged as a critical research topic, and several new methods for application at various preparation stages have been proposed to overcome the aforementioned hurdles. Here, we summarize the methods developed for enhancing the quality of cryo-samples at distinct stages of sample preparation, and we offer insights for developing future strategies based on diverse viewpoints. We anticipate that cryo-sample preparation will no longer be a limiting step in the single-particle cryo-EM field as increasing numbers of methods are developed in the near future, which will ultimately benefit the entire research community.
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Affiliation(s)
- Yixin Xu
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
| | - Shangyu Dang
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
- *Correspondence: Shangyu Dang,
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10
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Abstract
CryoEM has become the method of choice for determining the structure of large macromolecular complexes in multiple conformations, at resolutions where unambiguous atomic models can be built. Two effects that have limited progress in single-particle cryoEM are (i) beam-induced movement during image acquisition and (ii) protein adsorption and denaturation at the air-water interface during specimen preparation. While beam-induced movement now appears to have been resolved by all-gold specimen support grids with very small holes, surface effects at the air-water interface are a persistent problem. Strategies to overcome these effects include the use of alternative support films and new techniques for specimen deposition. We examine the future potential of recording perfect images of biological samples for routine structure determination at atomic resolution.
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11
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Kurumizaka H, Kujirai T, Takizawa Y. Contributions of Histone Variants in Nucleosome Structure and Function. J Mol Biol 2020; 433:166678. [PMID: 33065110 DOI: 10.1016/j.jmb.2020.10.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/08/2020] [Accepted: 10/08/2020] [Indexed: 11/19/2022]
Abstract
Chromatin compacts genomic DNA in eukaryotes. The primary chromatin unit is the nucleosome core particle, composed of four pairs of the core histones, H2A, H2B, H3, and H4, and 145-147 base pairs of DNA. Since replication, recombination, repair, and transcription take place in chromatin, the structure and dynamics of the nucleosome must be versatile. These nucleosome characteristics underlie the epigenetic regulation of genomic DNA. In higher eukaryotes, many histone variants have been identified as non-allelic isoforms, which confer nucleosome diversity. In this article, we review the manifold types of nucleosomes produced by histone variants, which play important roles in the epigenetic regulation of chromatin.
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Affiliation(s)
- Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
| | - Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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12
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Bai Y, Zhou BR. Structures of Native-like Nucleosomes: One Step Closer toward Understanding the Structure and Function of Chromatin. J Mol Biol 2020; 433:166648. [PMID: 32920051 DOI: 10.1016/j.jmb.2020.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 02/08/2023]
Abstract
Genomic DNA in eukaryotes is organized into chromatin through association with core histone proteins to form nucleosomes. To understand the structure and function of chromatin, we must determine the structures of nucleosomes containing native DNA sequences. However, to date, our knowledge of nucleosome structures is mainly based on the crystallographic studies of the nucleosomes containing non-native DNA sequences. Here, we discuss the technical issues related to the determination of the nucleosome structures and review the few structural studies on native-like nucleosomes. We show how an antibody fragment-aided single-particle cryo-EM can be a useful method to determine the structures of nucleosomes containing genomic DNA. Finally, we provide a perspective for future structural studies of some native-like nucleosomes that play critical roles in chromatin functions.
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Affiliation(s)
- Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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13
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Soman A, Liew CW, Teo HL, Berezhnoy NV, Olieric V, Korolev N, Rhodes D, Nordenskiöld L. The human telomeric nucleosome displays distinct structural and dynamic properties. Nucleic Acids Res 2020; 48:5383-5396. [PMID: 32374876 PMCID: PMC7261157 DOI: 10.1093/nar/gkaa289] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/01/2020] [Accepted: 05/05/2020] [Indexed: 12/21/2022] Open
Abstract
Telomeres protect the ends of our chromosomes and are key to maintaining genomic integrity during cell division and differentiation. However, our knowledge of telomeric chromatin and nucleosome structure at the molecular level is limited. Here, we aimed to define the structure, dynamics as well as properties in solution of the human telomeric nucleosome. We first determined the 2.2 Å crystal structure of a human telomeric nucleosome core particle (NCP) containing 145 bp DNA, which revealed the same helical path for the DNA as well as symmetric stretching in both halves of the NCP as that of the 145 bp ‘601’ NCP. In solution, the telomeric nucleosome exhibited a less stable and a markedly more dynamic structure compared to NCPs containing DNA positioning sequences. These observations provide molecular insights into how telomeric DNA forms nucleosomes and chromatin and advance our understanding of the unique biological role of telomeres.
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Affiliation(s)
- Aghil Soman
- School of Biological Sciences, Nanyang Technology University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Chong Wai Liew
- NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Hsiang Ling Teo
- NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Nikolay V Berezhnoy
- School of Biological Sciences, Nanyang Technology University, 60 Nanyang Drive, Singapore 637551, Singapore.,Singapore Centre for Environmental Sciences Engineering (SCELSE), Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Vincent Olieric
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Nikolay Korolev
- School of Biological Sciences, Nanyang Technology University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Daniela Rhodes
- School of Biological Sciences, Nanyang Technology University, 60 Nanyang Drive, Singapore 637551, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore.,School of Chemical and Biomolecular Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore
| | - Lars Nordenskiöld
- School of Biological Sciences, Nanyang Technology University, 60 Nanyang Drive, Singapore 637551, Singapore
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14
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Joppe M, D’Imprima E, Salustros N, Paithankar KS, Vonck J, Grininger M, Kühlbrandt W. The resolution revolution in cryoEM requires high-quality sample preparation: a rapid pipeline to a high-resolution map of yeast fatty acid synthase. IUCRJ 2020; 7:220-227. [PMID: 32148850 PMCID: PMC7055384 DOI: 10.1107/s2052252519017366] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 12/31/2019] [Indexed: 06/10/2023]
Abstract
Single-particle electron cryo-microscopy (cryoEM) has undergone a 'resolution revolution' that makes it possible to characterize megadalton (MDa) complexes at atomic resolution without crystals. To fully exploit the new opportunities in molecular microscopy, new procedures for the cloning, expression and purification of macromolecular complexes need to be explored. Macromolecular assemblies are often unstable, and invasive construct design or inadequate purification conditions and sample-preparation methods can result in disassembly or denaturation. The structure of the 2.6 MDa yeast fatty acid synthase (FAS) has been studied by electron microscopy since the 1960s. Here, a new, streamlined protocol for the rapid production of purified yeast FAS for structure determination by high-resolution cryoEM is reported. Together with a companion protocol for preparing cryoEM specimens on a hydrophilized graphene layer, the new protocol yielded a 3.1 Å resolution map of yeast FAS from 15 000 automatically picked particles within a day. The high map quality enabled a complete atomic model of an intact fungal FAS to be built.
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Affiliation(s)
- Mirko Joppe
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt am Main, Germany
| | - Edoardo D’Imprima
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Nina Salustros
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Karthik S. Paithankar
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Martin Grininger
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt am Main, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
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15
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Bendandi A, Dante S, Zia SR, Diaspro A, Rocchia W. Chromatin Compaction Multiscale Modeling: A Complex Synergy Between Theory, Simulation, and Experiment. Front Mol Biosci 2020; 7:15. [PMID: 32158765 PMCID: PMC7051991 DOI: 10.3389/fmolb.2020.00015] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/27/2020] [Indexed: 12/24/2022] Open
Abstract
Understanding the mechanisms that trigger chromatin compaction, its patterns, and the factors they depend on, is a fundamental and still open question in Biology. Chromatin compacts and reinforces DNA and is a stable but dynamic structure, to make DNA accessible to proteins. In recent years, computational advances have provided larger amounts of data and have made large-scale simulations more viable. Experimental techniques for the extraction and reconstitution of chromatin fibers have improved, reinvigorating theoretical and experimental interest in the topic and stimulating debate on points previously considered as certainties regarding chromatin. A great assortment of approaches has emerged, from all-atom single-nucleosome or oligonucleosome simulations to various degrees of coarse graining, to polymer models, to fractal-like structures and purely topological models. Different fiber-start patterns have been studied in theory and experiment, as well as different linker DNA lengths. DNA is a highly charged macromolecule, making ionic and electrostatic interactions extremely important for chromatin topology and dynamics. Indeed, the repercussions of varying ionic concentration have been extensively examined at the computational level, using all-atom, coarse-grained, and continuum techniques. The presence of high-curvature AT-rich segments in DNA can cause conformational variations, attesting to the fact that the role of DNA is both structural and electrostatic. There have been some tentative attempts to describe the force fields governing chromatin conformational changes and the energy landscapes of these transitions, but the intricacy of the system has hampered reaching a consensus. The study of chromatin conformations is an intrinsically multiscale topic, influenced by a wide range of biological and physical interactions, spanning from the atomic to the chromosome level. Therefore, powerful modeling techniques and carefully planned experiments are required for an overview of the most relevant phenomena and interactions. The topic provides fertile ground for interdisciplinary studies featuring a synergy between theoretical and experimental scientists from different fields and the cross-validation of respective results, with a multi-scale perspective. Here, we summarize some of the most representative approaches, and focus on the importance of electrostatics and solvation, often overlooked aspects of chromatin modeling.
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Affiliation(s)
- Artemi Bendandi
- Physics Department, University of Genoa, Genoa, Italy
- Nanophysics & NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Silvia Dante
- Nanophysics & NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Syeda Rehana Zia
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Alberto Diaspro
- Physics Department, University of Genoa, Genoa, Italy
- Nanophysics & NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Walter Rocchia
- Concept Lab, Istituto Italiano di Tecnologia, Genoa, Italy
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16
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17
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Makowski MM, Gaullier G, Luger K. Picking a nucleosome lock: Sequence- and structure-specific recognition of the nucleosome. J Biosci 2020; 45:13. [PMID: 31965991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The nucleosome presents a formidable barrier to DNA-templated transcription by the RNA polymerase II machinery. Overcoming this transcriptional barrier in a locus-specific manner requires sequence-specific recognition of nucleosomal DNA by 'pioneer' transcription factors (TFs). Cell fate decisions, in turn, depend on the coordinated action of pioneer TFs at cell lineage-specific gene regulatory elements. Although it is already appreciated that pioneer factors play a critical role in cell differentiation, our understanding of the structural and biochemical mechanisms by which they act is still rapidly expanding. Recent research has revealed novel insight into modes of nucleosome-TF binding and uncovered kinetic principles by which nucleosomal DNA compaction affects both TF binding and residence time. Here, we review progress and argue that these structural and kinetic studies suggest new models of gene regulation by pioneer TFs.
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Affiliation(s)
- Matthew M Makowski
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
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18
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Li S, Zheng EB, Zhao L, Liu S. Nonreciprocal and Conditional Cooperativity Directs the Pioneer Activity of Pluripotency Transcription Factors. Cell Rep 2019; 28:2689-2703.e4. [PMID: 31484078 PMCID: PMC6750763 DOI: 10.1016/j.celrep.2019.07.103] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/24/2019] [Accepted: 07/26/2019] [Indexed: 01/02/2023] Open
Abstract
Cooperative binding of transcription factors (TFs) to chromatin orchestrates gene expression programming and cell fate specification. However, the biophysical principles of TF cooperativity remain incompletely understood. Here we use single-molecule fluorescence microscopy to study the partnership between Sox2 and Oct4, two core members of the pluripotency gene regulatory network. We find that the ability of Sox2 to target DNA inside nucleosomes is strongly affected by the translational and rotational positioning of its binding motif. In contrast, Oct4 can access nucleosomal sites with equal capacities. Furthermore, the Sox2-Oct4 pair displays nonreciprocal cooperativity, with Oct4 modulating interaction of Sox2 with the nucleosome but not vice versa. Such cooperativity is conditional upon the composite motif's residing at specific nucleosomal locations. These results reveal that pioneer factors possess distinct chromatin-binding properties and suggest that the same set of TFs can differentially regulate gene activities on the basis of their motif positions in the nucleosomal context.
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Affiliation(s)
- Sai Li
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065, USA
| | - Eric Bo Zheng
- Laboratory of Evolutionary Genetics and Genomics, The Rockefeller University, New York, NY 10065, USA
| | - Li Zhao
- Laboratory of Evolutionary Genetics and Genomics, The Rockefeller University, New York, NY 10065, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065, USA.
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19
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Linking chromatin composition and structural dynamics at the nucleosome level. Curr Opin Struct Biol 2019; 56:46-55. [DOI: 10.1016/j.sbi.2018.11.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 01/31/2023]
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20
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Atomic resolution cryo-EM structure of a native-like CENP-A nucleosome aided by an antibody fragment. Nat Commun 2019; 10:2301. [PMID: 31127102 PMCID: PMC6534667 DOI: 10.1038/s41467-019-10247-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 04/26/2019] [Indexed: 12/20/2022] Open
Abstract
Genomic DNA in eukaryotes is organized into chromatin through association with core histones to form nucleosomes, each distinguished by their DNA sequences and histone variants. Here, we used a single-chain antibody fragment (scFv) derived from the anti-nucleosome antibody mAb PL2-6 to stabilize human CENP-A nucleosome containing a native α-satellite DNA and solved its structure by the cryo-electron microscopy (cryo-EM) to 2.6 Å resolution. In comparison, the corresponding cryo-EM structure of the free CENP-A nucleosome could only reach 3.4 Å resolution. We find that scFv binds to a conserved acidic patch on the histone H2A-H2B dimer without perturbing the nucleosome structure. Our results provide an atomic resolution cryo-EM structure of a nucleosome and insight into the structure and function of the CENP-A nucleosome. The scFv approach is applicable to the structural determination of other native-like nucleosomes with distinct DNA sequences. CENP-A histone variants replace histones H3 at centromeres. Here the authors use a single-chain antibody fragment (scFv) to stabilize human CENP-A nucleosome containing a native α-satellite DNA and solved its structure by cryo-EM to 2.6 Å resolution, providing insight into the structure and function of the CENP-A nucleosome.
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21
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D'Imprima E, Floris D, Joppe M, Sánchez R, Grininger M, Kühlbrandt W. Protein denaturation at the air-water interface and how to prevent it. eLife 2019; 8:42747. [PMID: 30932812 PMCID: PMC6443348 DOI: 10.7554/elife.42747] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/27/2019] [Indexed: 12/19/2022] Open
Abstract
Electron cryo-microscopy analyzes the structure of proteins and protein complexes in vitrified solution. Proteins tend to adsorb to the air-water interface in unsupported films of aqueous solution, which can result in partial or complete denaturation. We investigated the structure of yeast fatty acid synthase at the air-water interface by electron cryo-tomography and single-particle image processing. Around 90% of complexes adsorbed to the air-water interface are partly denatured. We show that the unfolded regions face the air-water interface. Denaturation by contact with air may happen at any stage of specimen preparation. Denaturation at the air-water interface is completely avoided when the complex is plunge-frozen on a substrate of hydrophilized graphene.
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Affiliation(s)
- Edoardo D'Imprima
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Davide Floris
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Mirko Joppe
- Buchmann Institute for Molecular Life Sciences, Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Frankfurt, Germany
| | - Ricardo Sánchez
- Sofja Kovalevskaja Group, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Martin Grininger
- Buchmann Institute for Molecular Life Sciences, Institute of Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Frankfurt, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
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22
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Zhou K, Gaullier G, Luger K. Nucleosome structure and dynamics are coming of age. Nat Struct Mol Biol 2018; 26:3-13. [PMID: 30532059 DOI: 10.1038/s41594-018-0166-x] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 11/07/2018] [Indexed: 11/09/2022]
Abstract
Since the first high-resolution structure of the nucleosome was reported in 1997, the available information on chromatin structure has increased very rapidly. Here, we review insights derived from cutting-edge biophysical and structural approaches applied to the study of nucleosome dynamics and nucleosome-binding factors, with a focus on the experimental advances driving the research. In addition, we highlight emerging challenges in nucleosome structural biology.
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Affiliation(s)
- Keda Zhou
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Guillaume Gaullier
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Karolin Luger
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.
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