1
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Mei J, Xu K, Huang Y, Zhang J, Qian Q, Dong J, Tong F, Yu W, Miao M. Cloning and characterization of the histone variant gene H2A.Z in Bombyx mori. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2024; 116:e22136. [PMID: 39016052 DOI: 10.1002/arch.22136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 06/30/2024] [Accepted: 07/09/2024] [Indexed: 07/18/2024]
Abstract
H2A.Z, the most evolutionarily conserved variant of histone H2A, plays a pivotal role in chromatin remodeling and contributes significantly to gene transcription and genome stability. However, the role of H2A.Z in the silkworm (Bombyx mori) remains unclear. In this study, we cloned the BmH2A.Z from B. mori. The open reading frame of BmH2A.Z is 390 bp, encoding 129 amino acids, with a confirmed molecular weight of 13.4 kDa through prokaryotic expression analysis. Sequence analysis revealed that BmH2A.Z has a conserved H2A.Z domain and is closely related to the systemic evolution of other known H2A.Zs. The expression profile of BmH2A.Z at various developmental stages of the B. mori exhibited the highest expression level in the 1st instar, followed by the grain stage and the 2nd instar, and the lowest expression level in the moth. The highest transcript level of BmH2A.Z was observed in the head, with relatively lower levels detected in the blood than in the other tissues under consideration. In addition, the upregulation of BmH2A.Z resulted in the amplified expression of B. mori nucleopolyhedrovirus (BmNPV) genes, thus facilitating the proliferation of BmNPV. This study establishes a foundation for investigating the role of BmH2A.Z in B. mori and its participation in virus-host interactions.
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Affiliation(s)
- Jun Mei
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Kunling Xu
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Yuyi Huang
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Jingwei Zhang
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Qitao Qian
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Jia Dong
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Fudan Tong
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Wei Yu
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Meng Miao
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
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2
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Eustermann S, Patel AB, Hopfner KP, He Y, Korber P. Energy-driven genome regulation by ATP-dependent chromatin remodellers. Nat Rev Mol Cell Biol 2024; 25:309-332. [PMID: 38081975 DOI: 10.1038/s41580-023-00683-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2023] [Indexed: 03/28/2024]
Abstract
The packaging of DNA into chromatin in eukaryotes regulates gene transcription, DNA replication and DNA repair. ATP-dependent chromatin remodelling enzymes (re)arrange nucleosomes at the first level of chromatin organization. Their Snf2-type motor ATPases alter histone-DNA interactions through a common DNA translocation mechanism. Whether remodeller activities mainly catalyse nucleosome dynamics or accurately co-determine nucleosome organization remained unclear. In this Review, we discuss the emerging mechanisms of chromatin remodelling: dynamic remodeller architectures and their interactions, the inner workings of the ATPase cycle, allosteric regulation and pathological dysregulation. Recent mechanistic insights argue for a decisive role of remodellers in the energy-driven self-organization of chromatin, which enables both stability and plasticity of genome regulation - for example, during development and stress. Different remodellers, such as members of the SWI/SNF, ISWI, CHD and INO80 families, process (epi)genetic information through specific mechanisms into distinct functional outputs. Combinatorial assembly of remodellers and their interplay with histone modifications, histone variants, DNA sequence or DNA-bound transcription factors regulate nucleosome mobilization or eviction or histone exchange. Such input-output relationships determine specific nucleosome positions and compositions with distinct DNA accessibilities and mediate differential genome regulation. Finally, remodeller genes are often mutated in diseases characterized by genome dysregulation, notably in cancer, and we discuss their physiological relevance.
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Affiliation(s)
- Sebastian Eustermann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Avinash B Patel
- Department of Molecular Biosciences, Robert H. Lurie Comprehensive Cancer Center, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
| | - Karl-Peter Hopfner
- Gene Center and Department of Biochemistry, Faculty of Chemistry and Pharmacy, LMU Munich, Munich, Germany
| | - Yuan He
- Department of Molecular Biosciences, Robert H. Lurie Comprehensive Cancer Center, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA.
| | - Philipp Korber
- Biomedical Center (BMC), Molecular Biology, Faculty of Medicine, LMU Munich, Martinsried, Germany.
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3
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Sotomayor-Lugo F, Iglesias-Barrameda N, Castillo-Aleman YM, Casado-Hernandez I, Villegas-Valverde CA, Bencomo-Hernandez AA, Ventura-Carmenate Y, Rivero-Jimenez RA. The Dynamics of Histone Modifications during Mammalian Zygotic Genome Activation. Int J Mol Sci 2024; 25:1459. [PMID: 38338738 PMCID: PMC10855761 DOI: 10.3390/ijms25031459] [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: 12/29/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
Mammalian fertilization initiates the reprogramming of oocytes and sperm, forming a totipotent zygote. During this intricate process, the zygotic genome undergoes a maternal-to-zygotic transition (MZT) and subsequent zygotic genome activation (ZGA), marking the initiation of transcriptional control and gene expression post-fertilization. Histone modifications are pivotal in shaping cellular identity and gene expression in many mammals. Recent advances in chromatin analysis have enabled detailed explorations of histone modifications during ZGA. This review delves into conserved and unique regulatory strategies, providing essential insights into the dynamic changes in histone modifications and their variants during ZGA in mammals. The objective is to explore recent advancements in leading mechanisms related to histone modifications governing this embryonic development phase in depth. These considerations will be useful for informing future therapeutic approaches that target epigenetic regulation in diverse biological contexts. It will also contribute to the extensive areas of evolutionary and developmental biology and possibly lay the foundation for future research and discussion on this seminal topic.
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Affiliation(s)
| | | | | | | | | | | | | | - Rene Antonio Rivero-Jimenez
- Abu Dhabi Stem Cells Center, Abu Dhabi P.O. Box 4600, United Arab Emirates; (F.S.-L.); (N.I.-B.); (Y.M.C.-A.); (I.C.-H.); (C.A.V.-V.); (A.A.B.-H.); (Y.V.-C.)
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4
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Arenas-Mena C, Akin S. Widespread priming of transcriptional regulatory elements by incipient accessibility or RNA polymerase II pause in early embryos of the sea urchin Strongylocentrotus purpuratus. Genetics 2023; 225:iyad145. [PMID: 37551428 PMCID: PMC10789315 DOI: 10.1093/genetics/iyad145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 05/17/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023] Open
Abstract
Transcriptional regulatory elements (TREs) are the primary nodes that control developmental gene regulatory networks. In embryo stages, larvae, and adult differentiated red spherule cells of the sea urchin Strongylocentrotus purpuratus, transcriptionally engaged TREs are detected by Precision Run-On Sequencing (PRO-seq), which maps genome-wide at base pair resolution the location of paused or elongating RNA polymerase II (Pol II). In parallel, TRE accessibility is estimated by the Assay for Transposase-Accessible Chromatin using Sequencing (ATAC-seq). Our analysis identifies surprisingly early and widespread TRE accessibility in 4-cell cleavage embryos that is not necessarily followed by concurrent or subsequent transcription. TRE transcriptional differences identified by PRO-seq provide more contrast among embryonic stages than ATAC-seq accessibility differences, in agreement with the apparent excess of accessible but inactive TREs during embryogenesis. Global TRE accessibility reaches a maximum around the 20-hour late blastula stage, which coincides with the consolidation of major embryo regionalizations and peak histone variant H2A.Z expression. A transcriptional potency model based on labile nucleosome TRE occupancy driven by DNA sequences and the prevalence of histone variants is proposed in order to explain the basal accessibility of transcriptionally inactive TREs during embryogenesis. However, our results would not reconcile well with labile nucleosome models based on simple A/T sequence enrichment. In addition, a large number of distal TREs become transcriptionally disengaged during developmental progression, in support of an early Pol II paused model for developmental gene regulation that eventually resolves in transcriptional activation or silencing. Thus, developmental potency in early embryos may be facilitated by incipient accessibility and transcriptional pause at TREs.
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Affiliation(s)
- Cesar Arenas-Mena
- Department of Biology, College of Staten Island, City University of New York (CUNY), 2800 Victory Boulevard, Staten Island, NY, 10314, USA
- PhD Programs in Biology and Biochemistry at the City University of New York (CUNY), Graduate Center, 365 Fifth Avenue, New York, NY, 10016, USA
| | - Serhat Akin
- Department of Biology, College of Staten Island, City University of New York (CUNY), 2800 Victory Boulevard, Staten Island, NY, 10314, USA
- PhD Program in Biology at the City University of New York (CUNY), Graduate Center, 365 Fifth Avenue, New York, NY, 10016, USA
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5
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Jamge B, Lorković ZJ, Axelsson E, Osakabe A, Shukla V, Yelagandula R, Akimcheva S, Kuehn AL, Berger F. Histone variants shape chromatin states in Arabidopsis. eLife 2023; 12:RP87714. [PMID: 37467143 PMCID: PMC10393023 DOI: 10.7554/elife.87714] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023] Open
Abstract
How different intrinsic sequence variations and regulatory modifications of histones combine in nucleosomes remain unclear. To test the importance of histone variants in the organization of chromatin we investigated how histone variants and histone modifications assemble in the Arabidopsis thaliana genome. We showed that a limited number of chromatin states divide euchromatin and heterochromatin into several subdomains. We found that histone variants are as significant as histone modifications in determining the composition of chromatin states. Particularly strong associations were observed between H2A variants and specific combinations of histone modifications. To study the role of H2A variants in organizing chromatin states we determined the role of the chromatin remodeler DECREASED IN DNA METHYLATION (DDM1) in the organization of chromatin states. We showed that the loss of DDM1 prevented the exchange of the histone variant H2A.Z to H2A.W in constitutive heterochromatin, resulting in significant effects on the definition and distribution of chromatin states in and outside of constitutive heterochromatin. We thus propose that dynamic exchanges of histone variants control the organization of histone modifications into chromatin states, acting as molecular landmarks.
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Affiliation(s)
- Bhagyshree Jamge
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
- Vienna BioCenterViennaAustria
| | - Zdravko J Lorković
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
| | - Elin Axelsson
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
| | - Akihisa Osakabe
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-kuTokyoJapan
- PRESTO, Japan Science and Technology Agency, HonchoKawaguchiJapan
| | - Vikas Shukla
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
- Vienna BioCenterViennaAustria
| | - Ramesh Yelagandula
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
- Institute of Molecular Biotechnology, IMBA, Dr. Bohr-Gasse 3ViennaAustria
| | - Svetlana Akimcheva
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
| | - Annika Luisa Kuehn
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
| | - Frédéric Berger
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenterViennaAustria
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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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Donovan BT, Luo Y, Meng Z, Poirier MG. The nucleosome unwrapping free energy landscape defines distinct regions of transcription factor accessibility and kinetics. Nucleic Acids Res 2023; 51:1139-1153. [PMID: 36688297 PMCID: PMC9943653 DOI: 10.1093/nar/gkac1267] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 11/27/2022] [Accepted: 01/16/2023] [Indexed: 01/24/2023] Open
Abstract
Transcription factors (TF) require access to target sites within nucleosomes to initiate transcription. The target site position within the nucleosome significantly influences TF occupancy, but how is not quantitatively understood. Using ensemble and single-molecule fluorescence measurements, we investigated the targeting and occupancy of the transcription factor, Gal4, at different positions within the nucleosome. We observe a dramatic decrease in TF occupancy to sites extending past 30 base pairs (bp) into the nucleosome which cannot be explained by changes in the TF dissociation rate or binding site orientation. Instead, the nucleosome unwrapping free energy landscape is the primary determinant of Gal4 occupancy by reducing the Gal4 binding rate. The unwrapping free energy landscape defines two distinct regions of accessibility and kinetics with a boundary at 30 bp into the nucleosome where the inner region is over 100-fold less accessible. The Gal4 binding rate in the inner region no longer depends on its concentration because it is limited by the nucleosome unwrapping rate, while the frequency of nucleosome rewrapping decreases because Gal4 exchanges multiple times before the nucleosome rewraps. Our findings highlight the importance of the nucleosome unwrapping free energy landscape on TF occupancy and dynamics that ultimately influences transcription initiation.
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Affiliation(s)
- Benjamin T Donovan
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Yi Luo
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Zhiyuan Meng
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Michael G Poirier
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA
- Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43214, USA
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8
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Long J, Carter B, Johnson ET, Ogas J. Contribution of the histone variant H2A.Z to expression of responsive genes in plants. Semin Cell Dev Biol 2023; 135:85-92. [PMID: 35474148 PMCID: PMC9588091 DOI: 10.1016/j.semcdb.2022.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 11/19/2022]
Abstract
The histone variant H2A.Z plays a critical role in chromatin-based processes such as transcription, replication, and repair in eukaryotes. Although many H2A.Z-associated processes and features are conserved in plants and animals, a distinguishing feature of plant chromatin is the enrichment of H2A.Z in the bodies of genes that exhibit dynamic expression, particularly in response to differentiation and the environment. Recent work sheds new light on the plant machinery that enables dynamic changes in H2A.Z enrichment and identifies additional chromatin-based pathways that contribute to transcriptional properties of H2A.Z-enriched chromatin. In particular, analysis of a variety of responsive loci reveals a repressive role for H2A.Z in expression of responsive genes and identifies roles for SWR1 and INO80 chromatin remodelers in enabling dynamic regulation of H2A.Z levels and transcription. These studies lay the groundwork for understanding how this ancient histone variant is harnessed by plants to enable responsive and dynamic gene expression (Graphical Abstract).
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Affiliation(s)
- Jiaxin Long
- Department of Biochemistry, Purdue University, West Lafayette, IN 47906, USA
| | - Benjamin Carter
- Laboratory of Epigenome Biology, Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Emily T Johnson
- Department of Biochemistry, Purdue University, West Lafayette, IN 47906, USA
| | - Joe Ogas
- Department of Biochemistry, Purdue University, West Lafayette, IN 47906, USA.
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9
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Li S, Wei T, Panchenko AR. Histone variant H2A.Z modulates nucleosome dynamics to promote DNA accessibility. Nat Commun 2023; 14:769. [PMID: 36765119 PMCID: PMC9918499 DOI: 10.1038/s41467-023-36465-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 02/02/2023] [Indexed: 02/12/2023] Open
Abstract
Nucleosomes, containing histone variants H2A.Z, are important for gene transcription initiation and termination, chromosome segregation and DNA double-strand break repair, among other functions. However, the underlying mechanisms of how H2A.Z influences nucleosome stability, dynamics and DNA accessibility are not well understood, as experimental and computational evidence remains inconclusive. Our modeling efforts of human nucleosome stability and dynamics, along with comparisons with experimental data show that the incorporation of H2A.Z results in a substantial decrease of the energy barrier for DNA unwrapping. This leads to the spontaneous DNA unwrapping of about forty base pairs from both ends, nucleosome gapping and increased histone plasticity, which otherwise is not observed for canonical nucleosomes. We demonstrate that both N- and C-terminal tails of H2A.Z play major roles in these events, whereas the H3.3 variant exerts a negligible impact in modulating the DNA end unwrapping. In summary, our results indicate that H2A.Z deposition makes nucleosomes more mobile and DNA more accessible to transcriptional machinery and other chromatin components.
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Affiliation(s)
- Shuxiang Li
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada
| | - Tiejun Wei
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada
| | - Anna R Panchenko
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada. .,Department of Biology and Molecular Sciences, Queen's University, Kingston, ON, Canada. .,School of Computing, Queen's University, Kingston, ON, Canada. .,Ontario Institute of Cancer Research, Toronto, Canada.
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10
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Obermeyer S, Stöckl R, Schnekenburger T, Kapoor H, Stempfl T, Schwartz U, Grasser KD. TFIIS Is Crucial During Early Transcript Elongation for Transcriptional Reprogramming in Response to Heat Stress. J Mol Biol 2023; 435:167917. [PMID: 36502880 DOI: 10.1016/j.jmb.2022.167917] [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: 10/31/2022] [Revised: 12/01/2022] [Accepted: 12/04/2022] [Indexed: 12/13/2022]
Abstract
In addition to the stage of transcriptional initiation, the production of mRNAs is regulated during elongation. Accordingly, the synthesis of mRNAs by RNA polymerase II (RNAPII) in the chromatin context is modulated by various transcript elongation factors. TFIIS is an elongation factor that stimulates the transcript cleavage activity of RNAPII to reactivate stalled elongation complexes at barriers to transcription including nucleosomes. Since Arabidopsis tfIIs mutants grow normally under standard conditions, we have exposed them to heat stress (HS), revealing that tfIIs plants are highly sensitive to elevated temperatures. Transcriptomic analyses demonstrate that particularly HS-induced genes are expressed at lower levels in tfIIs than in wildtype. Mapping the distribution of elongating RNAPII uncovered that in tfIIs plants RNAPII accumulates at the +1 nucleosome of genes that are upregulated upon HS. The promoter-proximal RNAPII accumulation in tfIIs under HS conditions conforms to that observed upon inhibition of the RNAPII transcript cleavage activity. Further analysis of the RNAPII accumulation downstream of transcriptional start sites illustrated that RNAPII stalling occurs at +1 nucleosomes that are depleted in the histone variant H2A.Z upon HS. Therefore, assistance of early transcript elongation by TFIIS is required for reprogramming gene expression to establish plant thermotolerance.
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Affiliation(s)
- Simon Obermeyer
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Richard Stöckl
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Tobias Schnekenburger
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Henna Kapoor
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Thomas Stempfl
- Center of Excellence for Fluorescent Bioanalytics (KFB), University of Regensburg, Am Biopark 9, D-93053 Regensburg, Germany
| | - Uwe Schwartz
- NGS Analysis Centre, Biology and Pre-Clinical Medicine, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Klaus D Grasser
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany.
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11
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Kravatsky YV, Chechetkin VR, Tchurikov NA, Kravatskaya GI. Genome-Wide Study of Colocalization between Genomic Stretches: A Method and Applications to the Regulation of Gene Expression. BIOLOGY 2022; 11:1422. [PMID: 36290327 PMCID: PMC9598420 DOI: 10.3390/biology11101422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
In this paper, we describe a method for the study of colocalization effects between stretch-stretch and stretch-point genome tracks based on a set of indices varying within the (-1, +1) interval. The indices combine the distances between the centers of neighboring stretches and their lengths. The extreme boundaries of the interval correspond to the complete colocalization of the genome tracks or its complete absence. We also obtained the relevant criteria of statistical significance for such indices using the complete permutation test. The method is robust with respect to strongly inhomogeneous positioning and length distribution of the genome tracks. On the basis of this approach, we created command-line software, the Genome Track Colocalization Analyzer. The software was tested, compared with other available packages, and applied to particular problems related to gene expression. The package, Genome Track Colocalization Analyzer (GTCA), is freely available to the users. GTCA complements our previous software, the Genome Track Analyzer, intended for the search for pairwise correlations between point-like genome tracks (also freely available). The corresponding details are provided in Data Availability Statement at the end of the text.
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Affiliation(s)
- Yuri V. Kravatsky
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Str., 32, 119991 Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir R. Chechetkin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Str., 32, 119991 Moscow, Russia
| | - Nickolai A. Tchurikov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Str., 32, 119991 Moscow, Russia
| | - Galina I. Kravatskaya
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Str., 32, 119991 Moscow, Russia
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12
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Carcamo CC, Poyton MF, Ranjan A, Park G, Louder RK, Feng XA, Kim JM, Dzu T, Wu C, Ha T. ATP binding facilitates target search of SWR1 chromatin remodeler by promoting one-dimensional diffusion on DNA. eLife 2022; 11:e77352. [PMID: 35876491 PMCID: PMC9365391 DOI: 10.7554/elife.77352] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 07/22/2022] [Indexed: 12/01/2022] Open
Abstract
One-dimensional (1D) target search is a well-characterized phenomenon for many DNA-binding proteins but is poorly understood for chromatin remodelers. Herein, we characterize the 1D scanning properties of SWR1, a conserved yeast chromatin remodeler that performs histone exchange on +1 nucleosomes adjacent to a nucleosome-depleted region (NDR) at gene promoters. We demonstrate that SWR1 has a kinetic binding preference for DNA of NDR length as opposed to gene-body linker length DNA. Using single and dual color single-particle tracking on DNA stretched with optical tweezers, we directly observe SWR1 diffusion on DNA. We found that various factors impact SWR1 scanning, including ATP which promotes diffusion through nucleotide binding rather than ATP hydrolysis. A DNA-binding subunit, Swc2, plays an important role in the overall diffusive behavior of the complex, as the subunit in isolation retains similar, although faster, scanning properties as the whole remodeler. ATP-bound SWR1 slides until it encounters a protein roadblock, of which we tested dCas9 and nucleosomes. The median diffusion coefficient, 0.024 μm2/s, in the regime of helical sliding, would mediate rapid encounter of NDR-flanking nucleosomes at length scales found in cellular chromatin.
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Affiliation(s)
- Claudia C Carcamo
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins UniversityBaltimoreUnited States
| | - Matthew F Poyton
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins UniversityBaltimoreUnited States
| | - Anand Ranjan
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Giho Park
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Robert K Louder
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Xinyu A Feng
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins UniversityBaltimoreUnited States
| | - Jee Min Kim
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Thuc Dzu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Carl Wu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins UniversityBaltimoreUnited States
- Howard Hughes Medical InstituteBaltimoreUnited States
- Johns Hopkins University, Department of Biomedical EngineeringBaltimoreUnited States
- Johns Hopkins University, Department of BiophysicsBaltimoreUnited States
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13
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Zananiri R, Mangapuram Venkata S, Gaydar V, Yahalom D, Malik O, Rudnizky S, Kleifeld O, Kaplan A, Henn A. Auxiliary ATP binding sites support DNA unwinding by RecBCD. Nat Commun 2022; 13:1806. [PMID: 35379800 PMCID: PMC8980037 DOI: 10.1038/s41467-022-29387-1] [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: 09/01/2017] [Accepted: 03/13/2022] [Indexed: 12/22/2022] Open
Abstract
The RecBCD helicase initiates double-stranded break repair in bacteria by processively unwinding DNA with a rate approaching ∼1,600 bp·s−1, but the mechanism enabling such a fast rate is unknown. Employing a wide range of methodologies — including equilibrium and time-resolved binding experiments, ensemble and single-molecule unwinding assays, and crosslinking followed by mass spectrometry — we reveal the existence of auxiliary binding sites in the RecC subunit, where ATP binds with lower affinity and distinct chemical interactions as compared to the known catalytic sites. The essentiality and functionality of these sites are demonstrated by their impact on the survival of E.coli after exposure to damage-inducing radiation. We propose a model by which RecBCD achieves its optimized unwinding rate, even when ATP is scarce, by using the auxiliary binding sites to increase the flux of ATP to its catalytic sites. RecBCD is a remarkably fast DNA helicase. Using a battery of biophysical methods, Zananiri et. al reveal additional, non-catalytic ATP binding sites that increase the ATP flux to the catalytic sites that allows fast unwinding when ATP is scarce.
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14
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Pnueli L, Melamed P. Epigenetic repression of gonadotropin gene expression via a GnRH-mediated DNA delivery system. Gene Ther 2022; 29:294-303. [PMID: 35301447 DOI: 10.1038/s41434-022-00325-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 02/08/2022] [Accepted: 02/18/2022] [Indexed: 11/09/2022]
Abstract
The reproductive axis is activated by gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gonadotropes to secrete hormones that drive gonadal function and steroidogenesis. Thus repression of this axis, which is conserved across mammals and sexes, can reduce steroid levels and/or prevent reproduction. Steroid-dependent pathologies, including various cancers, are commonly treated with GnRH super-analogs which have long-term side-effects, while humane solutions for controlling reproduction in domestic and wild animal populations are lacking. GnRH-conjugated toxins are undergoing clinical trials for GnRHR-expressing cancer cells, and have been examined for gonadotrope ablation in animals, but showed low and/or transient effects and administration of toxins has many potential complications. Here we exploit GnRH targeting to gonadotropes to deliver DNA encoding an effector that induces gonadotropin gene repressive epigenetic modifications which are perpetuated over time. Several layers of specificity are endowed through targeting to GnRHR-expressing cells and due to local cleavage of the peptide packaging the DNA; the DNA-encoded effector is expressed and directed to the target genes by the DNA binding domain of a highly specific transcription factor. This design has multiple advantages over existing methods of shutting down the reproductive axis, and its modular design should allow adaptation for broad applications.
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Affiliation(s)
- Lilach Pnueli
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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15
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Zaurin R, Ferrari R, Nacht AS, Carbonell J, Le Dily F, Font-Mateu J, de Llobet Cucalon LI, Vidal E, Lioutas A, Beato M, Vicent GP. A set of accessible enhancers enables the initial response of breast cancer cells to physiological progestin concentrations. Nucleic Acids Res 2021; 49:12716-12731. [PMID: 34850111 PMCID: PMC8682742 DOI: 10.1093/nar/gkab1125] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/20/2021] [Accepted: 10/26/2021] [Indexed: 11/14/2022] Open
Abstract
Here, we report that in T47D breast cancer cells 50 pM progestin is sufficient to activate cell cycle entry and the progesterone gene expression program. At this concentration, equivalent to the progesterone blood levels found around the menopause, progesterone receptor (PR) binds only to 2800 genomic sites, which are accessible to ATAC cleavage prior to hormone exposure. These highly accessible sites (HAs) are surrounded by well-organized nucleosomes and exhibit breast enhancer features, including estrogen receptor alpha (ERα), higher FOXA1 and BRD4 (bromodomain containing 4) occupancy. Although HAs are enriched in RAD21 and CTCF, PR binding is the driving force for the most robust interactions with hormone-regulated genes. HAs show higher frequency of 3D contacts among themselves than with other PR binding sites, indicating colocalization in similar compartments. Gene regulation via HAs is independent of classical coregulators and ATP-activated remodelers, relying mainly on MAP kinase activation that enables PR nuclear engagement. HAs are also preferentially occupied by PR and ERα in breast cancer xenografts derived from MCF-7 cells as well as from patients, indicating their potential usefulness as targets for therapeutic intervention.
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Affiliation(s)
- Roser Zaurin
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Roberto Ferrari
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Ana Silvina Nacht
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Jose Carbonell
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Francois Le Dily
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Jofre Font-Mateu
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Lara Isabel de Llobet Cucalon
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Enrique Vidal
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Antonios Lioutas
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain
| | - Miguel Beato
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Barcelona Institute for Science and Technology (BIST), Barcelona, 08003, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, 08003, Spain
| | - Guillermo P Vicent
- Center for Genomic Regulation (CRG), Barcelona, 08003, Spain.,Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Científicas (IBMB-CSIC), Barcelona, 08003, Spain
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16
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What makes a histone variant a variant: Changing H2A to become H2A.Z. PLoS Genet 2021; 17:e1009950. [PMID: 34871303 PMCID: PMC8675926 DOI: 10.1371/journal.pgen.1009950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 12/16/2021] [Accepted: 11/16/2021] [Indexed: 01/01/2023] Open
Abstract
Chromatin structure and underlying DNA accessibility is modulated by the incorporation of histone variants. H2A.Z, a variant of the H2A core histone family, plays a distinct and essential role in a diverse set of biological functions including gene regulation and maintenance of heterochromatin-euchromatin boundaries. Although it is currently unclear how the replacement of H2A with H2A.Z can regulate gene expression, the variance in their amino acid sequence likely contributes to their functional differences. To tease apart regions of H2A.Z that confer its unique identity, a set of plasmids expressing H2A-H2A.Z hybrids from the native H2A.Z promoter were examined for their ability to recapitulate H2A.Z function. First, we found that the H2A.Z M6 region was necessary and sufficient for interaction with the SWR1-C chromatin remodeler. Remarkably, the combination of only 9 amino acid changes, the H2A.Z M6 region, K79 and L81 (two amino acids in the α2-helix), were sufficient to fully rescue growth phenotypes of the htz1Δ mutant. Furthermore, combining three unique H2A.Z regions (K79 and L81, M6, C-terminal tail) was sufficient for expression of H2A.Z-dependent heterochromatin-proximal genes and GAL1 derepression. Surprisingly, hybrid constructs that restored the transcription of H2A.Z-dependent genes, did not fully recapitulate patterns of H2A.Z-specific enrichment at the tested loci. This suggested that H2A.Z function in transcription regulation may be at least partially independent of its specific localization in chromatin. Together, this work has identified three regions that can confer specific H2A.Z-identity to replicative H2A, furthering our understanding of what makes a histone variant a variant. Chromatin structure in eukaryotes is integral to all aspects of genome function. Many essential biological processes depend on chromatin remodeling for regulating access to DNA such as transcription, replication, and DNA repair. One highly conserved method of chromatin remodeling is the replacement of the replicative histones with a histone variant. Unlike replicative histones, which are distributed equally in chromatin during DNA replication, histone variants can be transcribed and deposited throughout the cell cycle at specific locations. Once incorporated, small differences in a histone variant’s protein sequence and structure can result in unique chromatin neighbourhoods with distinct character and function from the replicative histone. Therefore, to better understand the role of a histone variant, it is important to define how its protein sequence contributes to its unique identity. Here, using a hybrid gene approach in budding yeast, we systematically determine which amino acids contribute to H2A.Z unique identity as a histone variant.
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17
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Khamis H, Rudnizky S, Melamed P, Kaplan A. Single molecule characterization of the binding kinetics of a transcription factor and its modulation by DNA sequence and methylation. Nucleic Acids Res 2021; 49:10975-10987. [PMID: 34606618 PMCID: PMC8565314 DOI: 10.1093/nar/gkab843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/04/2021] [Accepted: 09/24/2021] [Indexed: 12/14/2022] Open
Abstract
The interaction of transcription factors with their response elements in DNA is emerging as a highly complex process, whose characterization requires measuring the full distribution of binding and dissociation times in a well-controlled assay. Here, we present a single-molecule assay that exploits the thermal fluctuations of a DNA hairpin to detect the association and dissociation of individual, unlabeled transcription factors. We demonstrate this new approach by following the binding of Egr1 to its consensus motif and the three binding sites found in the promoter of the Lhb gene, and find that both association and dissociation are modulated by the 9 bp core motif and the sequences around it. In addition, CpG methylation modulates the dissociation kinetics in a sequence and position-dependent manner, which can both stabilize or destabilize the complex. Together, our findings show how variations in sequence and methylation patterns synergistically extend the spectrum of a protein's binding properties, and demonstrate how the proposed approach can provide new insights on the function of transcription factors.
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Affiliation(s)
- Hadeel Khamis
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
- Faculty of Physics, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Sergei Rudnizky
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
- Faculty of Biomedical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
- Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
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18
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Colino-Sanguino Y, Clark SJ, Valdes-Mora F. The H2A.Z-nuclesome code in mammals: emerging functions. Trends Genet 2021; 38:273-289. [PMID: 34702577 DOI: 10.1016/j.tig.2021.10.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 12/12/2022]
Abstract
H2A.Z is a histone variant that provides specific structural and docking-side properties to the nucleosome, resulting in diverse and specialised molecular and cellular functions. In this review, we discuss the latest studies uncovering new functional aspects of mammalian H2A.Z in gene transcription, including pausing and elongation of RNA polymerase II (RNAPII) and enhancer activity; DNA repair; DNA replication; and 3D chromatin structure. We also review the recently described role of H2A.Z in embryonic development, cell differentiation, neurodevelopment, and brain function. In conclusion, our cumulative knowledge of H2A.Z over the past 40 years, in combination with the implementation of novel molecular technologies, is unravelling an unexpected and complex role of histone variants in gene regulation and disease.
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Affiliation(s)
- Yolanda Colino-Sanguino
- Cancer Epigenetics Biology and Therapeutics, Precision Medicine Theme, Children's Cancer Institute, Sydney, NSW, Australia; School of Children and Women Health, University of NSW Sydney, Sydney, NSW, Australia.
| | - Susan J Clark
- Epigenetics Research Laboratory, Genomics and Epigenetics Division, Garvan Institute of Medical Research, Sydney, NSW, Australia; St. Vincent's Clinical School, University of NSW Sydney, Sydney, NSW, Australia
| | - Fatima Valdes-Mora
- Cancer Epigenetics Biology and Therapeutics, Precision Medicine Theme, Children's Cancer Institute, Sydney, NSW, Australia; School of Children and Women Health, University of NSW Sydney, Sydney, NSW, Australia.
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19
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Single-molecule studies of helicases and translocases in prokaryotic genome-maintenance pathways. DNA Repair (Amst) 2021; 108:103229. [PMID: 34601381 DOI: 10.1016/j.dnarep.2021.103229] [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: 05/03/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022]
Abstract
Helicases involved in genomic maintenance are a class of nucleic-acid dependent ATPases that convert the energy of ATP hydrolysis into physical work to execute irreversible steps in DNA replication, repair, and recombination. Prokaryotic helicases provide simple models to understand broadly conserved molecular mechanisms involved in manipulating nucleic acids during genome maintenance. Our understanding of the catalytic properties, mechanisms of regulation, and roles of prokaryotic helicases in DNA metabolism has been assembled through a combination of genetic, biochemical, and structural methods, further refined by single-molecule approaches. Together, these investigations have constructed a framework for understanding the mechanisms that maintain genomic integrity in cells. This review discusses recent single-molecule insights into molecular mechanisms of prokaryotic helicases and translocases.
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20
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Abstract
The world of long non-coding RNAs (lncRNAs) has opened up massive new prospects in understanding the regulation of gene expression. Not only are there seemingly almost infinite numbers of lncRNAs in the mammalian cell, but they have highly diverse mechanisms of action. In the nucleus, some are chromatin-associated, transcribed from transcriptional enhancers (eRNAs) and/or direct changes in the epigenetic landscape with profound effects on gene expression. The pituitary gonadotrope is responsible for activation of reproduction through production and secretion of appropriate levels of the gonadotropic hormones. As such, it exemplifies a cell whose function is defined through changes in developmental and temporal patterns of gene expression, including those that are hormonally induced. Roles for diverse distal regulatory elements and eRNAs in gonadotrope biology have only just begun to emerge. Here, we will present an overview of the different kinds of lncRNAs that alter gene expression, and what is known about their roles in regulating some of the key gonadotrope genes. We will also review various screens that have detected differentially expressed pituitary lncRNAs associated with changes in reproductive state and those whose expression is found to play a role in gonadotrope-derived nonfunctioning pituitary adenomas. We hope to shed light on this exciting new field, emphasize the open questions, and encourage research to illuminate the roles of lncRNAs in various endocrine systems.
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Affiliation(s)
- Tal Refael
- Faculty of Biology, Technion Israel Institute of Technology, Haifa 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion Israel Institute of Technology, Haifa 32000, Israel
- Correspondence: Philippa Melamed, PhD, Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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21
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Pnueli L, Shalev D, Refael T, David C, Boehm U, Melamed P. Proliferating primary pituitary cells as a model for studying regulation of gonadotrope chromatin and gene expression. Mol Cell Endocrinol 2021; 533:111349. [PMID: 34090968 DOI: 10.1016/j.mce.2021.111349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/20/2021] [Accepted: 05/29/2021] [Indexed: 12/27/2022]
Abstract
The chromatin organization of the gonadotropin gene promoters in the pituitary gonadotropes plays a major role in determining how these gene are activated, but is difficult to study because of the low numbers of these cells in the pituitary gland. Here, we set out to create a cell model to study gonadotropin chromatin, and found that by optimizing cell culture conditions, we can maintain stable proliferating cultures of primary non-transformed gonadotrope cells over weeks to months. Although expression of the gonadotropin genes drops very low, these cells are enriched in gonadotrope markers and respond to GnRH. Furthermore, >85% of the cells contained Lhb and/or Fshb mature transcripts; though these were virtually restricted to the nuclei. The gonadotropes were harvested initially due to expression of dTOMATO, following activation of Cre recombinase by the Gnrhr promoter. Over 6 mo in culture, a similar proportion of the recombined DNA was maintained (i.e. cells derived from the original gonadotropes or having acquired Gnrhr-promoter activity), together with cells of a distinct origin. The cells are enriched with markers of proliferating pituitary and stem cells, including Sox2, suggesting that multipotent precursor cells might have proliferated and differentiated into gonadotrope-like cells. These cell cultures offer a new and versatile methodology for research in gonadotrope differentiation and function, and can provide enough primary cells for chromatin immunoprecipitation and epigenetic analysis, while our initial studies also indicate a possible regulatory mechanism that might be involved in the nuclear export of gonadotropin gene mRNAs.
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Affiliation(s)
- Lilach Pnueli
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Dor Shalev
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Tal Refael
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Cfir David
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Ulrich Boehm
- Department of Experimental Pharmacology, Center for Molecular Signaling, Saarland University School of Medicine, Homburg, Germany
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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22
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OsARP6 Is Involved in Internode Elongation by Regulating Cell-Cycle-Related Genes. Biomolecules 2021; 11:biom11081100. [PMID: 34439766 PMCID: PMC8393719 DOI: 10.3390/biom11081100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 11/17/2022] Open
Abstract
The SWR1 complex (SWR1-C) is important for the deposition of histone variant H2A.Z into chromatin to regulate gene expression. Characterization of SWR1-C subunits in Arabidopsis thaliana has revealed their role in variety of developmental processes. Oryza sativa actin related protein 6 (OsARP6) is a subunit of rice SWR1-C. Its role in rice plant development is unknown. Here, we examined the subcellular localization, expression patterns, and loss of function phenotypes for this protein and found that OsARP6 is a nuclear localized protein, and is broadly expressed. OsARP6 interacted with OsPIE1, a central ATPase subunit of rice SWR1-C. The osarp6 knockout mutants displayed pleiotropic phenotypic alterations in vegetative and reproductive traits, including semi-dwarf phenotype, lower tillers number, short leaf length, changes in spikelet morphology, and seed abortion. Microscopic thin sectioning of the top internode revealed that the dwarf phenotype of osarp6 was due to reduced number of cells rather than reduced cell length. The altered transcript level of genes involved in cell division suggested that OsARP6 affects cell cycle regulation. In addition, H2A.Z levels were reduced at the promoters and transcription start sites (TSS) of the regulated genes in osarp6 plants. Together, these results suggest that OsARP6 is involved in rice plant development, and H2A.Z deposition.
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23
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Rudnizky S, Khamis H, Ginosar Y, Goren E, Melamed P, Kaplan A. Extended and dynamic linker histone-DNA Interactions control chromatosome compaction. Mol Cell 2021; 81:3410-3421.e4. [PMID: 34192510 DOI: 10.1016/j.molcel.2021.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/01/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023]
Abstract
Chromatosomes play a fundamental role in chromatin regulation, but a detailed understanding of their structure is lacking, partially due to their complex dynamics. Using single-molecule DNA unzipping with optical tweezers, we reveal that linker histone interactions with DNA are remarkably extended, with the C-terminal domain binding both DNA linkers as far as approximately ±140 bp from the dyad. In addition to a symmetrical compaction of the nucleosome core governed by globular domain contacts at the dyad, the C-terminal domain compacts the nucleosome's entry and exit. These interactions are dynamic, exhibit rapid binding and dissociation, are sensitive to phosphorylation of a specific residue, and are crucial to determining the symmetry of the chromatosome's core. Extensive unzipping of the linker DNA, which mimics its invasion by motor proteins, shifts H1 into an asymmetric, off-dyad configuration and triggers nucleosome decompaction, highlighting the plasticity of the chromatosome structure and its potential regulatory role.
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Affiliation(s)
- Sergei Rudnizky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Hadeel Khamis
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel; Faculty of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Yuval Ginosar
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Efrat Goren
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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24
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Cole L, Kurscheid S, Nekrasov M, Domaschenz R, Vera DL, Dennis JH, Tremethick DJ. Multiple roles of H2A.Z in regulating promoter chromatin architecture in human cells. Nat Commun 2021; 12:2524. [PMID: 33953180 PMCID: PMC8100287 DOI: 10.1038/s41467-021-22688-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 03/25/2021] [Indexed: 01/02/2023] Open
Abstract
Chromatin accessibility of a promoter is fundamental in regulating transcriptional activity. The histone variant H2A.Z has been shown to contribute to this regulation, but its role has remained poorly understood. Here, we prepare high-depth maps of the position and accessibility of H2A.Z-containing nucleosomes for all human Pol II promoters in epithelial, mesenchymal and isogenic cancer cell lines. We find that, in contrast to the prevailing model, many different types of active and inactive promoter structures are observed that differ in their nucleosome organization and sensitivity to MNase digestion. Key aspects of an active chromatin structure include positioned H2A.Z MNase resistant nucleosomes upstream or downstream of the TSS, and a MNase sensitive nucleosome at the TSS. Furthermore, the loss of H2A.Z leads to a dramatic increase in the accessibility of transcription factor binding sites. Collectively, these results suggest that H2A.Z has multiple and distinct roles in regulating gene expression dependent upon its location in a promoter.
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Affiliation(s)
- Lauren Cole
- College of Arts and Sciences, Department of Biological Sciences, Florida State University, Tallahassee, FL, USA
| | - Sebastian Kurscheid
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Maxim Nekrasov
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Renae Domaschenz
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Daniel L Vera
- College of Arts and Sciences, Department of Biological Sciences, Florida State University, Tallahassee, FL, USA
- Department of Genetics, Blavatnik Institute, Paul F. Glenn Center for Biology of Aging Research, Harvard Medical School, Boston, MA, USA
| | - Jonathan H Dennis
- College of Arts and Sciences, Department of Biological Sciences, Florida State University, Tallahassee, FL, USA.
| | - David J Tremethick
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australia.
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25
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Dai L, Xiao X, Pan L, Shi L, Xu N, Zhang Z, Feng X, Ma L, Dou S, Wang P, Zhu B, Li W, Zhou Z. Recognition of the inherently unstable H2A nucleosome by Swc2 is a major determinant for unidirectional H2A.Z exchange. Cell Rep 2021; 35:109183. [PMID: 34038732 DOI: 10.1016/j.celrep.2021.109183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 12/24/2022] Open
Abstract
The multisubunit chromatin remodeler SWR1/SRCAP/p400 replaces the nucleosomal H2A-H2B dimer with the free-form H2A.Z-H2B dimer, but the mechanism governing the unidirectional H2A-to-H2A.Z exchange remains elusive. Here, we perform single-molecule force spectroscopy to dissect the disassembly/reassembly processes of the H2A nucleosome and H2A.Z nucleosome. We find that the N-terminal 1-135 residues of yeast SWR1 complex protein 2 (previously termed Swc2-Z) facilitate the disassembly of nucleosomes containing H2A but not H2A.Z. The Swc2-mediated nucleosome disassembly/reassembly requires the inherently unstable H2A nucleosome, whose instability is conferred by three H2A α2-helical residues, Gly47, Pro49, and Ile63, as they selectively weaken the structural rigidity of the H2A-H2B dimer. It also requires Swc2-ZN (residues 1-37) that directly anchors to the H2A nucleosome and functions in the SWR1-catalyzed H2A.Z replacement in vitro and yeast H2A.Z deposition in vivo. Our findings provide mechanistic insights into how the SWR1 complex discriminates between the H2A nucleosome and H2A.Z nucleosome, establishing a simple paradigm for the governance of unidirectional H2A.Z exchange.
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Affiliation(s)
- Linchang Dai
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xue Xiao
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lu Pan
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Liuxin Shi
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ning Xu
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhuqiang Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaoli Feng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lu Ma
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shuoxing Dou
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pengye Wang
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Bing Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Li
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.
| | - Zheng Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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26
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Abstract
Eukaryotic nucleosomes organize chromatin by wrapping 147 bp of DNA around a histone core particle comprising two molecules each of histone H2A, H2B, H3 and H4. The DNA entering and exiting the particle may be bound by the linker histone H1. Whereas deposition of bulk histones is confined to S-phase, paralogs of the common histones, known as histone variants, are available to carry out functions throughout the cell cycle and accumulate in post-mitotic cells. Histone variants confer different structural properties on nucleosomes by wrapping more or less DNA or by altering nucleosome stability. They carry out specialized functions in DNA repair, chromosome segregation and regulation of transcription initiation, or perform tissue-specific roles. In this Cell Science at a Glance article and the accompanying poster, we briefly examine new insights into histone origins and discuss variants from each of the histone families, focusing on how structural differences may alter their functions. Summary: Histone variants change the structural properties of nucleosomes by wrapping more or less DNA, altering nucleosome stability or carrying out specialized functions.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
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27
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Basu A, Bobrovnikov DG, Ha T. DNA mechanics and its biological impact. J Mol Biol 2021; 433:166861. [PMID: 33539885 DOI: 10.1016/j.jmb.2021.166861] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 02/06/2023]
Abstract
Almost all nucleoprotein interactions and DNA manipulation events involve mechanical deformations of DNA. Extraordinary progresses in single-molecule, structural, and computational methods have characterized the average mechanical properties of DNA, such as bendability and torsional rigidity, in high resolution. Further, the advent of sequencing technology has permitted measuring, in high-throughput, how such mechanical properties vary with sequence and epigenetic modifications along genomes. We review these recent technological advancements, and discuss how they have contributed to the emerging idea that variations in the mechanical properties of DNA play a fundamental role in regulating, genome-wide, diverse processes involved in chromatin organization.
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Affiliation(s)
- Aakash Basu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Dmitriy G Bobrovnikov
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA
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28
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Histone variant H2A.B-H2B dimers are spontaneously exchanged with canonical H2A-H2B in the nucleosome. Commun Biol 2021; 4:191. [PMID: 33580188 PMCID: PMC7881002 DOI: 10.1038/s42003-021-01707-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/11/2021] [Indexed: 01/07/2023] Open
Abstract
H2A.B is an evolutionarily distant histone H2A variant that accumulates on DNA repair sites, DNA replication sites, and actively transcribing regions in genomes. In cells, H2A.B exchanges rapidly in chromatin, but the mechanism has remained enigmatic. In the present study, we found that the H2A.B-H2B dimer incorporated within the nucleosome exchanges with the canonical H2A-H2B dimer without assistance from additional factors, such as histone chaperones and nucleosome remodelers. High-speed atomic force microscopy revealed that the H2A.B nucleosome, but not the canonical H2A nucleosome, transiently forms an intermediate "open conformation", in which two H2A.B-H2B dimers may be detached from the H3-H4 tetramer and bind to the DNA regions near the entry/exit sites. Mutational analyses revealed that the H2A.B C-terminal region is responsible for the adoption of the open conformation and the H2A.B-H2B exchange in the nucleosome. These findings provide mechanistic insights into the histone exchange of the H2A.B nucleosome.
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29
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Gamarra N, Narlikar GJ. Collaboration through chromatin: motors of transcription and chromatin structure. J Mol Biol 2021; 433:166876. [PMID: 33556407 DOI: 10.1016/j.jmb.2021.166876] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 01/09/2023]
Abstract
Packaging of the eukaryotic genome into chromatin places fundamental physical constraints on transcription. Clarifying how transcription operates within these constraints is essential to understand how eukaryotic gene expression programs are established and maintained. Here we review what is known about the mechanisms of transcription on chromatin templates. Current models indicate that transcription through chromatin is accomplished by the combination of an inherent nucleosome disrupting activity of RNA polymerase and the action of ATP-dependent chromatin remodeling motors. Collaboration between these two types of molecular motors is proposed to occur at all stages of transcription through diverse mechanisms. Further investigation of how these two motors combine their basic activities is essential to clarify the interdependent relationship between genome structure and transcription.
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Affiliation(s)
- Nathan Gamarra
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States; TETRAD Graduate Program, University of California, San Francisco, San Francisco, United States
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
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30
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Morgan A, LeGresley S, Fischer C. Remodeler Catalyzed Nucleosome Repositioning: Influence of Structure and Stability. Int J Mol Sci 2020; 22:ijms22010076. [PMID: 33374740 PMCID: PMC7793527 DOI: 10.3390/ijms22010076] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/04/2020] [Accepted: 12/16/2020] [Indexed: 02/06/2023] Open
Abstract
The packaging of the eukaryotic genome into chromatin regulates the storage of genetic information, including the access of the cell’s DNA metabolism machinery. Indeed, since the processes of DNA replication, translation, and repair require access to the underlying DNA, several mechanisms, both active and passive, have evolved by which chromatin structure can be regulated and modified. One mechanism relies upon the function of chromatin remodeling enzymes which couple the free energy obtained from the binding and hydrolysis of ATP to the mechanical work of repositioning and rearranging nucleosomes. Here, we review recent work on the nucleosome mobilization activity of this essential family of molecular machines.
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31
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Shalev D, Melamed P. The role of the hypothalamus and pituitary epigenomes in central activation of the reproductive axis at puberty. Mol Cell Endocrinol 2020; 518:111031. [PMID: 32956708 DOI: 10.1016/j.mce.2020.111031] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 08/02/2020] [Accepted: 09/08/2020] [Indexed: 12/19/2022]
Abstract
Puberty is programmed through a multifactorial gene network which works to activate the pulsatile secretion of the gonadotropin releasing hormone (GnRH), and subsequently elevate circulating levels of the pituitary gonadotropins that stimulate gonadal activity. Although this developmental transition normally occurs at a limited age-range in individuals of the same genetic background and environment, pubertal onset can occur prematurely or be delayed following changes in ambient conditions, or due to genetic variations or mutations, many of which have remained elusive due to their location in distal regulatory elements. Growing evidence is pointing to a pivotal role for the epigenome in regulating key genes in the reproductive hypothalamus and pituitary at this time, which might mediate some of the plasticity of pubertal timing. This review will address epigenetic mechanisms which have been demonstrated in the KNDy neurons that increase the output of pulsatile GnRH, and those involved in activation of the GnRH gene and its receptor, and describes how GnRH utilizes epigenetic mechanisms to stimulate transcription of the pituitary gonadotropin genes in the context of the chromatin landscape.
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Affiliation(s)
- Dor Shalev
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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32
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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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33
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Tafessu A, Banaszynski LA. Establishment and function of chromatin modification at enhancers. Open Biol 2020; 10:200255. [PMID: 33050790 PMCID: PMC7653351 DOI: 10.1098/rsob.200255] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 09/22/2020] [Indexed: 12/17/2022] Open
Abstract
How a single genome can give rise to distinct cell types remains a fundamental question in biology. Mammals are able to specify and maintain hundreds of cell fates by selectively activating unique subsets of their genome. This is achieved, in part, by enhancers-genetic elements that can increase transcription of both nearby and distal genes. Enhancers can be identified by their unique chromatin signature, including transcription factor binding and the enrichment of specific histone post-translational modifications, histone variants, and chromatin-associated cofactors. How each of these chromatin features contributes to enhancer function remains an area of intense study. In this review, we provide an overview of enhancer-associated chromatin states, and the proteins and enzymes involved in their establishment. We discuss recent insights into the effects of the enhancer chromatin state on ongoing transcription versus their role in the establishment of new transcription programmes, such as those that occur developmentally. Finally, we highlight the role of enhancer chromatin in new conceptual advances in gene regulation such as condensate formation.
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Affiliation(s)
| | - Laura A. Banaszynski
- UT Southwestern Medical Center, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Obstetrics and Gynecology, Children's Research Institute, Hamon Center for Regenerative Science and Medicine, Dallas, TX 75390-8511, USA
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34
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Bar-Sadeh B, Rudnizky S, Pnueli L, Bentley GR, Stöger R, Kaplan A, Melamed P. Unravelling the role of epigenetics in reproductive adaptations to early-life environment. Nat Rev Endocrinol 2020; 16:519-533. [PMID: 32620937 DOI: 10.1038/s41574-020-0370-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/11/2020] [Indexed: 11/08/2022]
Abstract
Reproductive function adjusts in response to environmental conditions in order to optimize success. In humans, this plasticity includes age of pubertal onset, hormone levels and age at menopause. These reproductive characteristics vary across populations with distinct lifestyles and following specific childhood events, and point to a role for the early-life environment in shaping adult reproductive trajectories. Epigenetic mechanisms respond to external signals, exert long-term effects on gene expression and have been shown in animal and cellular studies to regulate normal reproductive function, strongly implicating their role in these adaptations. Moreover, human cohort data have revealed differential DNA methylation signatures in proxy tissues that are associated with reproductive phenotypic variation, although the cause-effect relationships are difficult to discern, calling for additional complementary approaches to establish functionality. In this Review, we summarize how adult reproductive function can be shaped by childhood events. We discuss why the influence of the childhood environment on adult reproductive function is an important consideration in understanding how reproduction is regulated and necessitates consideration by clinicians treating women with diverse life histories. The resolution of the molecular mechanisms responsible for human reproductive plasticity could also lead to new approaches for intervention by targeting these epigenetic modifications.
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Affiliation(s)
- Ben Bar-Sadeh
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Sergei Rudnizky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Lilach Pnueli
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Reinhard Stöger
- Department of Biological Sciences, University of Nottingham, Nottingham, UK
| | - Ariel Kaplan
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
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35
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Abstract
Nucleosome dynamics and properties are central to all forms of genomic activities. Among the core histones, H3 variants play a pivotal role in modulating nucleosome structure and function. Here, we focus on the impact of H3 variants on various facets of development. The deposition of the replicative H3 variant following DNA replication is essential for the transmission of the epigenomic information encoded in posttranscriptional modifications. Through this process, replicative H3 maintains cell fate while, in contrast, the replacement H3.3 variant opposes cell differentiation during early embryogenesis. In later steps of development, H3.3 and specialized H3 variants are emerging as new, important regulators of terminal cell differentiation, including neurons and gametes. The specific pathways that regulate the dynamics of the deposition of H3.3 are paramount during reprogramming events that drive zygotic activation and the initiation of a new cycle of development.
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Affiliation(s)
- Benjamin Loppin
- Laboratoire de Biologie et de Modélisation de la Cellule, CNRS UMR 5239, Ecole Normale Supérieure de Lyon, University of Lyon, F-69007 Lyon, France;
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), 1030 Vienna, Austria;
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36
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Patty BJ, Hainer SJ. Non-Coding RNAs and Nucleosome Remodeling Complexes: An Intricate Regulatory Relationship. BIOLOGY 2020; 9:E213. [PMID: 32784701 PMCID: PMC7465399 DOI: 10.3390/biology9080213] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/30/2020] [Accepted: 08/06/2020] [Indexed: 12/17/2022]
Abstract
Eukaryotic genomes are pervasively transcribed, producing both coding and non-coding RNAs (ncRNAs). ncRNAs are diverse and a critical family of biological molecules, yet much remains unknown regarding their functions and mechanisms of regulation. ATP-dependent nucleosome remodeling complexes, in modifying chromatin structure, play an important role in transcriptional regulation. Recent findings show that ncRNAs regulate nucleosome remodeler activities at many levels and that ncRNAs are regulatory targets of nucleosome remodelers. Further, a series of recent screens indicate this network of regulatory interactions is more expansive than previously appreciated. Here, we discuss currently described regulatory interactions between ncRNAs and nucleosome remodelers and contextualize their biological functions.
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Affiliation(s)
| | - Sarah J. Hainer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA;
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37
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Sato S, Tanaka N, Arimura Y, Kujirai T, Kurumizaka H. The N-terminal and C-terminal halves of histone H2A.Z independently function in nucleosome positioning and stability. Genes Cells 2020; 25:538-546. [PMID: 32500630 PMCID: PMC7496805 DOI: 10.1111/gtc.12791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/28/2020] [Accepted: 05/08/2020] [Indexed: 01/21/2023]
Abstract
Nucleosome positioning and stability affect gene regulation in eukaryotic chromatin. Histone H2A.Z is an evolutionally conserved histone variant that forms mobile and unstable nucleosomes in vivo and in vitro. In the present study, we reconstituted nucleosomes containing human H2A.Z.1 mutants, in which the N‐terminal or C‐terminal half of H2A.Z.1 was replaced by the corresponding canonical H2A region. We found that the N‐terminal portion of H2A.Z.1 is involved in flexible nucleosome positioning, whereas the C‐terminal portion leads to weak H2A.Z.1‐H2B association in the nucleosome. These results indicate that the N‐terminal and C‐terminal portions are independently responsible for the H2A.Z.1 nucleosome characteristics.
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Affiliation(s)
- Shoko Sato
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Naoki Tanaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Yasuhiro Arimura
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan.,Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan.,Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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38
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Kujirai T, Kurumizaka H. Transcription through the nucleosome. Curr Opin Struct Biol 2020; 61:42-49. [DOI: 10.1016/j.sbi.2019.10.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 11/28/2022]
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39
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Lei B, Berger F. H2A Variants in Arabidopsis: Versatile Regulators of Genome Activity. PLANT COMMUNICATIONS 2020; 1:100015. [PMID: 33404536 PMCID: PMC7747964 DOI: 10.1016/j.xplc.2019.100015] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/13/2019] [Accepted: 12/11/2019] [Indexed: 05/16/2023]
Abstract
The eukaryotic nucleosome prevents access to the genome. Convergently evolving histone isoforms, also called histone variants, form diverse families that are enriched over distinct features of plant genomes. Among the diverse families of plant histone variants, H2A.Z exclusively marks genes. Here we review recent research progress on the genome-wide distribution patterns and deposition of H2A.Z in plants as well as its association with histone modifications and roles in plant chromatin regulation. We also discuss some hypotheses that explain the different findings about the roles of H2A.Z in plants.
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40
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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41
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Chen Z, Gabizon R, Brown AI, Lee A, Song A, Díaz-Celis C, Kaplan CD, Koslover EF, Yao T, Bustamante C. High-resolution and high-accuracy topographic and transcriptional maps of the nucleosome barrier. eLife 2019; 8:48281. [PMID: 31364986 PMCID: PMC6744274 DOI: 10.7554/elife.48281] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/30/2019] [Indexed: 12/16/2022] Open
Abstract
Nucleosomes represent mechanical and energetic barriers that RNA Polymerase II (Pol II) must overcome during transcription. A high-resolution description of the barrier topography, its modulation by epigenetic modifications, and their effects on Pol II nucleosome crossing dynamics, is still missing. Here, we obtain topographic and transcriptional (Pol II residence time) maps of canonical, H2A.Z, and monoubiquitinated H2B (uH2B) nucleosomes at near base-pair resolution and accuracy. Pol II crossing dynamics are complex, displaying pauses at specific loci, backtracking, and nucleosome hopping between wrapped states. While H2A.Z widens the barrier, uH2B heightens it, and both modifications greatly lengthen Pol II crossing time. Using the dwell times of Pol II at each nucleosomal position we extract the energetics of the barrier. The orthogonal barrier modifications of H2A.Z and uH2B, and their effects on Pol II dynamics rationalize their observed enrichment in +1 nucleosomes and suggest a mechanism for selective control of gene expression.
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Affiliation(s)
- Zhijie Chen
- Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Ronen Gabizon
- Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, United States
| | - Aidan I Brown
- Department of Physics, University of California, San Diego, San Diego, United States
| | - Antony Lee
- Department of Physics, University of California, Berkeley, Berkeley, United States
| | - Aixin Song
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - César Díaz-Celis
- Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, San Diego, United States
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Carlos Bustamante
- Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.,Department of Physics, University of California, Berkeley, Berkeley, United States.,Jason L Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, United States.,Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Chemistry, University of California, Berkeley, Berkeley, United States.,Kavli Energy Nanoscience Institute, University of California, Berkeley, Berkeley, United States
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42
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Talbert PB, Meers MP, Henikoff S. Old cogs, new tricks: the evolution of gene expression in a chromatin context. Nat Rev Genet 2019; 20:283-297. [PMID: 30886348 DOI: 10.1038/s41576-019-0105-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sophisticated gene-regulatory mechanisms probably evolved in prokaryotes billions of years before the emergence of modern eukaryotes, which inherited the same basic enzymatic machineries. However, the epigenomic landscapes of eukaryotes are dominated by nucleosomes, which have acquired roles in genome packaging, mitotic condensation and silencing parasitic genomic elements. Although the molecular mechanisms by which nucleosomes are displaced and modified have been described, just how transcription factors, histone variants and modifications and chromatin regulators act on nucleosomes to regulate transcription is the subject of considerable ongoing study. We explore the extent to which these transcriptional regulatory components function in the context of the evolutionarily ancient role of chromatin as a barrier to processes acting on DNA and how chromatin proteins have diversified to carry out evolutionarily recent functions that accompanied the emergence of differentiation and development in multicellular eukaryotes.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Michael P Meers
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
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43
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Rudnizky S, Khamis H, Malik O, Squires AH, Meller A, Melamed P, Kaplan A. Single-molecule DNA unzipping reveals asymmetric modulation of a transcription factor by its binding site sequence and context. Nucleic Acids Res 2019; 46:1513-1524. [PMID: 29253225 PMCID: PMC5815098 DOI: 10.1093/nar/gkx1252] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 12/11/2017] [Indexed: 12/31/2022] Open
Abstract
Most functional transcription factor (TF) binding sites deviate from their ‘consensus’ recognition motif, although their sites and flanking sequences are often conserved across species. Here, we used single-molecule DNA unzipping with optical tweezers to study how Egr-1, a TF harboring three zinc fingers (ZF1, ZF2 and ZF3), is modulated by the sequence and context of its functional sites in the Lhb gene promoter. We find that both the core 9 bp bound to Egr-1 in each of the sites, and the base pairs flanking them, modulate the affinity and structure of the protein–DNA complex. The effect of the flanking sequences is asymmetric, with a stronger effect for the sequence flanking ZF3. Characterization of the dissociation time of Egr-1 revealed that a local, mechanical perturbation of the interactions of ZF3 destabilizes the complex more effectively than a perturbation of the ZF1 interactions. Our results reveal a novel role for ZF3 in the interaction of Egr-1 with other proteins and the DNA, providing insight on the regulation of Lhb and other genes by Egr-1. Moreover, our findings reveal the potential of small changes in DNA sequence to alter transcriptional regulation, and may shed light on the organization of regulatory elements at promoters.
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Affiliation(s)
- Sergei Rudnizky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Hadeel Khamis
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Faculty of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Omri Malik
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Allison H Squires
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Amit Meller
- Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.,Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Philippa Melamed
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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44
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Torres ES, Deal RB. The histone variant H2A.Z and chromatin remodeler BRAHMA act coordinately and antagonistically to regulate transcription and nucleosome dynamics in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:144-162. [PMID: 30742338 PMCID: PMC7259472 DOI: 10.1111/tpj.14281] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/28/2018] [Accepted: 12/18/2018] [Indexed: 05/17/2023]
Abstract
Plants adapt to environmental changes by regulating transcription and chromatin organization. The histone H2A variant H2A.Z and the SWI2/SNF2 ATPase BRAHMA (BRM) have overlapping roles in positively and negatively regulating environmentally responsive genes in Arabidopsis, but the extent of this overlap was uncharacterized. Both factors have been associated with various changes in nucleosome positioning and stability in different contexts, but their specific roles in transcriptional regulation and chromatin organization need further characterization. We show that H2A.Z and BRM co-localize at thousands of sites, where they interact both cooperatively and antagonistically in transcriptional repression and activation of genes involved in development and responses to environmental stimuli. We identified eight classes of genes that show distinct relationships between H2A.Z and BRM with respect to their roles in transcription. These include activating and silencing transcription both redundantly and antagonistically. We found that H2A.Z contributes to a range of different nucleosome properties, while BRM stabilizes nucleosomes where it binds and destabilizes or repositions flanking nucleosomes. We also found that, at many genes regulated by both BRM and H2A.Z, both factors overlap with binding sites of the light-regulated transcription factor FAR1-Related Sequence 9 (FRS9) and that a subset of these FRS9 binding sites are dependent on H2A.Z and BRM for accessibility. Collectively, we comprehensively characterized the antagonistic and cooperative contributions of H2A.Z and BRM to transcriptional regulation, and illuminated several interrelated roles in chromatin organization. The variability observed in their individual functions implies that both BRM and H2A.Z have more context-dependent roles than previously assumed.
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Affiliation(s)
- E. Shannon Torres
- Department of Biology, Emory University, Atlanta, GA 30322
- Graduate Program in Genetics and Molecular Biology of the Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 30322
| | - Roger B. Deal
- Department of Biology, Emory University, Atlanta, GA 30322
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45
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The base pair-scale diffusion of nucleosomes modulates binding of transcription factors. Proc Natl Acad Sci U S A 2019; 116:12161-12166. [PMID: 31147470 DOI: 10.1073/pnas.1815424116] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The structure of promoter chromatin determines the ability of transcription factors (TFs) to bind to DNA and therefore has a profound effect on the expression levels of genes. However, the role of spontaneous nucleosome movements in this process is not fully understood. Here, we developed a single-molecule optical tweezers assay capable of simultaneously characterizing the base pair-scale diffusion of a nucleosome on DNA and the binding of a TF, using the luteinizing hormone β subunit gene (Lhb) promoter and Egr-1 as a model system. Our results demonstrate that nucleosomes undergo confined diffusion, and that the incorporation of the histone variant H2A.Z serves to partially relieve this confinement, inducing a different type of nucleosome repositioning. The increase in diffusion leads to exposure of a TF's binding site and facilitates its association with the DNA, which, in turn, biases the subsequent movement of the nucleosome. Our findings suggest the use of mobile nucleosomes as a general transcriptional regulatory mechanism.
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46
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Braadland PR, Urbanucci A. Chromatin reprogramming as an adaptation mechanism in advanced prostate cancer. Endocr Relat Cancer 2019; 26:R211-R235. [PMID: 30844748 DOI: 10.1530/erc-18-0579] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/13/2022]
Abstract
Tumor evolution is based on the ability to constantly mutate and activate different pathways under the selective pressure of targeted therapies. Epigenetic alterations including those of the chromatin structure are associated with tumor initiation, progression and drug resistance. Many cancers, including prostate cancer, present enlarged nuclei, and chromatin appears altered and irregular. These phenotypic changes are likely to result from epigenetic dysregulation. High-throughput sequencing applied to bulk samples and now to single cells has made it possible to study these processes in unprecedented detail. It is therefore timely to review the impact of chromatin relaxation and increased DNA accessibility on prostate cancer growth and drug resistance, and their effects on gene expression. In particular, we focus on the contribution of chromatin-associated proteins such as the bromodomain-containing proteins to chromatin relaxation. We discuss the consequence of this for androgen receptor transcriptional activity and briefly summarize wider gain-of-function effects on other oncogenic transcription factors and implications for more effective prostate cancer treatment.
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Affiliation(s)
- Peder Rustøen Braadland
- Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Alfonso Urbanucci
- Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
- Centre for Molecular Medicine Norway, Nordic European Molecular Biology Laboratory Partnership, Forskningsparken, University of Oslo, Oslo, Norway
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47
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Zananiri R, Malik O, Rudnizky S, Gaydar V, Kreiserman R, Henn A, Kaplan A. Synergy between RecBCD subunits is essential for efficient DNA unwinding. eLife 2019; 8:e40836. [PMID: 30601118 PMCID: PMC6338465 DOI: 10.7554/elife.40836] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/01/2019] [Indexed: 12/12/2022] Open
Abstract
The subunits of the bacterial RecBCD act in coordination, rapidly and processively unwinding DNA at the site of a double strand break. RecBCD is able to displace DNA-binding proteins, suggesting that it generates high forces, but the specific role of each subunit in the force generation is unclear. Here, we present a novel optical tweezers assay that allows monitoring the activity of RecBCD's individual subunits, when they are part of an intact full complex. We show that RecBCD and its subunits are able to generate forces up to 25-40 pN without a significant effect on their velocity. Moreover, the isolated RecD translocates fast but is a weak helicase with limited processivity. Experiments at a broad range of [ATP] and forces suggest that RecD unwinds DNA as a Brownian ratchet, rectified by ATP binding, and that the presence of the other subunits shifts the ratchet equilibrium towards the post-translocation state.
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Affiliation(s)
- Rani Zananiri
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Omri Malik
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
- Russell Berrie Nanotechnology InstituteTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Sergei Rudnizky
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Vera Gaydar
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Roman Kreiserman
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
- Faculty of PhysicsTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Arnon Henn
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Ariel Kaplan
- Faculty of BiologyTechnion – Israel Institute of TechnologyHaifaIsrael
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48
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Feldman A, Saleh A, Pnueli L, Qiao S, Shlomi T, Boehm U, Melamed P. Sensitivity of pituitary gonadotropes to hyperglycemia leads to epigenetic aberrations and reduced follicle‐stimulating hormone levels. FASEB J 2018; 33:1020-1032. [DOI: 10.1096/fj.201800943r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Alona Feldman
- Faculty of BiologyTechnion–Israel Institute of Technology Haifa Israel
| | - Ayah Saleh
- Faculty of BiologyTechnion–Israel Institute of Technology Haifa Israel
| | - Lilach Pnueli
- Faculty of BiologyTechnion–Israel Institute of Technology Haifa Israel
| | - Sen Qiao
- Experimental PharmacologyCenter for Molecular Signaling (PZMS)Saarland University School of Medicine Homburg Germany
| | - Tomer Shlomi
- Faculty of BiologyTechnion–Israel Institute of Technology Haifa Israel
- Department of Computer ScienceTechnion–Israel Institute of Technology Haifa Israel
| | - Ulrich Boehm
- Experimental PharmacologyCenter for Molecular Signaling (PZMS)Saarland University School of Medicine Homburg Germany
| | - Philippa Melamed
- Faculty of BiologyTechnion–Israel Institute of Technology Haifa Israel
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49
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Kang J, Kim YW, Kim A. Histone variants H3.3 and H2A.Z are incorporated into the β-globin locus during transcription activation via different mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:S1874-9399(18)30082-8. [PMID: 29879504 DOI: 10.1016/j.bbagrm.2018.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/21/2018] [Accepted: 05/31/2018] [Indexed: 12/13/2022]
Abstract
Histone variants H3.3 and H2A.Z are often enriched in enhancers and transcriptionally active genes. However, the incorporation dynamics of these variants and the mechanisms of their incorporation are unclear. Here, we examined the distribution of H3.3 and H2A.Z in the human β-globin locus and analyzed their incorporation dynamics during transcription activation. Locus control region hypersensitive sites (LCR HSs), acting as enhancers, and active globin genes were enriched by H3.3 and H2A.Z in erythroid K562 cells, but inactive globin genes were not. Both variants were dynamically incorporated into the β-globin locus after transcription induction in MEL/ch11 cells, and prior to gene transcription the LCR HSs became enriched with the variants. In the activated β-globin gene, H3.3 was highly incorporated during transcription, whereas H2A.Z incorporation appeared to precede it. To further explore the relationship between gene transcription and variant incorporation, we deleted the LCR HS3 enhancer or the β-globin proximal promoter from the β-globin locus using the CRISPR-Cas9 genome editing system. H2A.Z was incorporated into the β-globin gene in the locus lacking promoter, even though the β-globin gene transcription was abolished by these deletions. However, H3.3 incorporation was reduced in the untranscribed β-globin gene. These results suggest that H3.3 and H2A.Z are systematically incorporated into the LCR enhancer and β-globin gene as part of transcription activation, but that their incorporation is carried out via different mechanisms.
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Affiliation(s)
- Jin Kang
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 46241, Republic of Korea
| | - Yea Woon Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 46241, Republic of Korea
| | - AeRi Kim
- Department of Molecular Biology, College of Natural Sciences, Pusan National University, Busan 46241, Republic of Korea.
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50
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Malik O, Khamis H, Rudnizky S, Kaplan A. The mechano-chemistry of a monomeric reverse transcriptase. Nucleic Acids Res 2018; 45:12954-12962. [PMID: 29165701 PMCID: PMC5728418 DOI: 10.1093/nar/gkx1168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/08/2017] [Indexed: 01/28/2023] Open
Abstract
Retroviral reverse transcriptase catalyses the synthesis of an integration-competent dsDNA molecule, using as a substrate the viral RNA. Using optical tweezers, we follow the Murine Leukemia Virus reverse transcriptase as it performs strand-displacement polymerization on a template under mechanical force. Our results indicate that reverse transcriptase functions as a Brownian ratchet, with dNTP binding as the rectifying reaction of the ratchet. We also found that reverse transcriptase is a relatively passive enzyme, able to polymerize on structured templates by exploiting their thermal breathing. Finally, our results indicate that the enzyme enters the recently characterized backtracking state from the pre-translocation complex.
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Affiliation(s)
- Omri Malik
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Hadeel Khamis
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Faculty of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Sergei Rudnizky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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