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Fetian T, Grover A, Arndt KM. Histone H2B ubiquitylation: Connections to transcription and effects on chromatin structure. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195018. [PMID: 38331024 PMCID: PMC11098702 DOI: 10.1016/j.bbagrm.2024.195018] [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: 10/06/2023] [Revised: 01/30/2024] [Accepted: 02/05/2024] [Indexed: 02/10/2024]
Abstract
Nucleosomes are major determinants of eukaryotic genome organization and regulation. Many studies, incorporating a diversity of experimental approaches, have been focused on identifying and discerning the contributions of histone post-translational modifications to DNA-centered processes. Among these, monoubiquitylation of H2B (H2Bub) on K120 in humans or K123 in budding yeast is a critical histone modification that has been implicated in a wide array of DNA transactions. H2B is co-transcriptionally ubiquitylated and deubiquitylated via the concerted action of an extensive network of proteins. In addition to altering the chemical and physical properties of the nucleosome, H2Bub is important for the proper control of gene expression and for the deposition of other histone modifications. In this review, we discuss the molecular mechanisms underlying the ubiquitylation cycle of H2B and how it connects to the regulation of transcription and chromatin structure.
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Affiliation(s)
- Tasniem Fetian
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States of America
| | - Aakash Grover
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States of America
| | - Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States of America.
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2
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Garcia J, Paul S, Shukla S, Zhong Y, Beauchemin K, Bartholomew B. Conformational switching of Arp5 subunit differentially regulates INO80 chromatin remodeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593625. [PMID: 38766108 PMCID: PMC11100795 DOI: 10.1101/2024.05.10.593625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The INO80 chromatin remodeler is a versatile enzyme capable of several functions, including spacing nucleosomes equal distances apart, precise positioning of nucleosomes based on DNA shape/sequence and exchanging histone dimers. Within INO80, the Arp5 subunit plays a central role in INO80 remodeling, evidenced by its interactions with the histone octamer, nucleosomal and extranucleosomal DNA, and its necessity in linking INO80's ATPase activity to nucleosome movement. Our investigation reveals that the grappler domain of Arp5 interacts with the acidic pocket of nucleosomes through two distinct mechanisms: an arginine anchor or a hydrophobic/acidic patch. These two modes of binding serve distinct functions within INO80 as shown in vivo by mutations in these regions resulting in varying phenotypes and in vitro by diverse effects on nucleosome mobilization. Our findings suggest that the hydrophobic/acidic patch of Arp5 is likely important for dimer exchange by INO80, while the arginine anchor is crucial for mobilizing nucleosomes.
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Affiliation(s)
- Jeison Garcia
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
- Department of Internal Medicine, Division of Medical Genetics. McGovern Medical School, UT Health Science Center at Houston, TX 77030
- These authors contributed equally
| | - Somnath Paul
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
- These authors contributed equally
| | - Shagun Shukla
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
- These authors contributed equally
| | - Yuan Zhong
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
| | - Karissa Beauchemin
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Blaine Bartholomew
- Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, Houston, TX 77054
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3
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Langenbacher AD, Lu F, Tsang L, Huang ZYS, Keer B, Tian Z, Eide A, Pellegrini M, Nakano H, Nakano A, Chen JN. Rtf1-dependent transcriptional pausing regulates cardiogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.13.562296. [PMID: 37873297 PMCID: PMC10592831 DOI: 10.1101/2023.10.13.562296] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
During heart development, a well-characterized network of transcription factors initiates cardiac gene expression and defines the precise timing and location of cardiac progenitor specification. However, our understanding of the post-initiation transcriptional events that regulate cardiac gene expression is still incomplete. The PAF1C component Rtf1 is a transcription regulatory protein that modulates pausing and elongation of RNA Pol II, as well as cotranscriptional histone modifications. Here we report that Rtf1 is essential for cardiogenesis in fish and mammals, and that in the absence of Rtf1 activity, cardiac progenitors arrest in an immature state. We found that Rtf1's Plus3 domain, which confers interaction with the transcriptional pausing and elongation regulator Spt5, was necessary for cardiac progenitor formation. ChIP-seq analysis further revealed changes in the occupancy of RNA Pol II around the transcription start site (TSS) of cardiac genes in rtf1 morphants reflecting a reduction in transcriptional pausing. Intriguingly, inhibition of pause release in rtf1 morphants and mutants restored the formation of cardiac cells and improved Pol II occupancy at the TSS of key cardiac genes. Our findings highlight the crucial role that transcriptional pausing plays in promoting normal gene expression levels in a cardiac developmental context.
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Affiliation(s)
- Adam D. Langenbacher
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Fei Lu
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Luna Tsang
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Zi Yi Stephanie Huang
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Benjamin Keer
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Zhiyu Tian
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Alette Eide
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Haruko Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jau-Nian Chen
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles, California, United States of America
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4
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Jia H, Dantuluri S, Margulies S, Smith V, Lever R, Allers T, Koh J, Chen S, Maupin-Furlow JA. RecJ3/4-aRNase J form a Ubl-associated nuclease complex functioning in survival against DNA damage in Haloferax volcanii. mBio 2023; 14:e0085223. [PMID: 37458473 PMCID: PMC10470531 DOI: 10.1128/mbio.00852-23] [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: 04/05/2023] [Accepted: 06/02/2023] [Indexed: 09/02/2023] Open
Abstract
Nucleases are strictly regulated and often localized in the cell to avoid the uncontrolled degradation of DNA and RNA. Here, a new type of nuclease complex, composed of RecJ3, RecJ4, and aRNase J, was identified through its ATP-dependent association with the ubiquitin-like SAMP1 and AAA-ATPase Cdc48a. The complex was discovered in Haloferax volcanii, an archaeon lacking an RNA exosome. Genetic analysis revealed aRNase J to be essential and RecJ3, RecJ4, and Cdc48a to function in the recovery from DNA damage including genotoxic agents that generate double-strand breaks. The RecJ3:RecJ4:aRNase J complex (isolated in 2:2:1 stoichiometry) functioned primarily as a 3'-5' exonuclease in hydrolyzing RNA and ssDNA, with the mechanism non-processive for ssDNA. aRNase J could also be purified as a homodimer that catalyzed endoribonuclease activity and, thus, was not restricted to the 5'-3' exonuclease activity typical of aRNase J homologs. Moreover, RecJ3 and RecJ4 could be purified as a 560-kDa subcomplex in equimolar subunit ratio with nuclease activities mirroring the full RecJ3/4-aRNase J complex. These findings prompted reconstitution assays that suggested RecJ3/4 could suppress, alter, and/or outcompete the nuclease activities of aRNase J. Based on the phenotypic results, this control mechanism of aRNase J by RecJ3/4 is not necessary for cell growth but instead appears important for DNA repair. IMPORTANCE Nucleases are critical for various cellular processes including DNA replication and repair. Here, a dynamic type of nuclease complex is newly identified in the archaeon Haloferax volcanii, which is missing the canonical RNA exosome. The complex, composed of RecJ3, RecJ4, and aRNase J, functions primarily as a 3'-5' exonuclease and was discovered through its ATP-dependent association with the ubiquitin-like SAMP1 and Cdc48a. aRNase J alone forms a homodimer that has endonuclease function and, thus, is not restricted to 5'-3' exonuclease activity typical of other aRNase J enzymes. RecJ3/4 appears to suppress, alter, and/or outcompete the nuclease activities of aRNase J. While aRNase J is essential for growth, RecJ3/4, Cdc48a, and SAMPs are important for recovery against DNA damage. These biological distinctions may correlate with the regulated nuclease activity of aRNase J in the RecJ3/4-aRNaseJ complex.
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Affiliation(s)
- Huiyong Jia
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
| | - Swathi Dantuluri
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
| | - Shae Margulies
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
| | - Victoria Smith
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Rebecca Lever
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jin Koh
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA
| | - Sixue Chen
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA
- Genetics Institute, University of Florida, Gainesville, Florida, USA
- Department of Biology, College of Liberal Arts and Sciences, University of Florida, Gainesville, Florida, USA
| | - Julie A. Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, Florida, USA
- Genetics Institute, University of Florida, Gainesville, Florida, USA
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5
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Ellison MA, Namjilsuren S, Shirra M, Blacksmith M, Schusteff R, Kerr E, Fang F, Xiang Y, Shi Y, Arndt K. Spt6 directly interacts with Cdc73 and is required for Paf1 complex occupancy at active genes in Saccharomyces cerevisiae. Nucleic Acids Res 2023; 51:4814-4830. [PMID: 36928138 PMCID: PMC10250246 DOI: 10.1093/nar/gkad180] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 03/18/2023] Open
Abstract
The Paf1 complex (Paf1C) is a conserved transcription elongation factor that regulates transcription elongation efficiency, facilitates co-transcriptional histone modifications, and impacts molecular processes linked to RNA synthesis, such as polyA site selection. Coupling of the activities of Paf1C to transcription elongation requires its association with RNA polymerase II (Pol II). Mutational studies in yeast identified Paf1C subunits Cdc73 and Rtf1 as important mediators of Paf1C association with Pol II on active genes. While the interaction between Rtf1 and the general elongation factor Spt5 is relatively well-understood, the interactions involving Cdc73 have not been fully elucidated. Using a site-specific protein cross-linking strategy in yeast cells, we identified direct interactions between Cdc73 and two components of the Pol II elongation complex, the elongation factor Spt6 and the largest subunit of Pol II. Both of these interactions require the tandem SH2 domain of Spt6. We also show that Cdc73 and Spt6 can interact in vitro and that rapid depletion of Spt6 dissociates Paf1 from chromatin, altering patterns of Paf1C-dependent histone modifications genome-wide. These results reveal interactions between Cdc73 and the Pol II elongation complex and identify Spt6 as a key factor contributing to the occupancy of Paf1C at active genes in Saccharomyces cerevisiae.
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Affiliation(s)
- Mitchell A Ellison
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | | - Margaret K Shirra
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Matthew S Blacksmith
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Rachel A Schusteff
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Eleanor M Kerr
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Fei Fang
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Yufei Xiang
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Yi Shi
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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6
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Fetian T, McShane BM, Horan NL, Shodja DN, True JD, Mosley AL, Arndt KM. Paf1 complex subunit Rtf1 stimulates H2B ubiquitylation by interacting with the highly conserved N-terminal helix of Rad6. Proc Natl Acad Sci U S A 2023; 120:e2220041120. [PMID: 37216505 PMCID: PMC10235976 DOI: 10.1073/pnas.2220041120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/05/2023] [Indexed: 05/24/2023] Open
Abstract
Histone modifications coupled to transcription elongation play important roles in regulating the accuracy and efficiency of gene expression. The monoubiquitylation of a conserved lysine in H2B (K123 in Saccharomyces cerevisiae; K120 in humans) occurs cotranscriptionally and is required for initiating a histone modification cascade on active genes. H2BK123 ubiquitylation (H2BK123ub) requires the RNA polymerase II (RNAPII)-associated Paf1 transcription elongation complex (Paf1C). Through its histone modification domain (HMD), the Rtf1 subunit of Paf1C directly interacts with the ubiquitin conjugase Rad6, leading to the stimulation of H2BK123ub in vivo and in vitro. To understand the molecular mechanisms that target Rad6 to its histone substrate, we identified the site of interaction for the HMD on Rad6. Using in vitro cross-linking followed by mass spectrometry, we localized the primary contact surface for the HMD to the highly conserved N-terminal helix of Rad6. Using a combination of genetic, biochemical, and in vivo protein cross-linking experiments, we characterized separation-of-function mutations in S. cerevisiae RAD6 that greatly impair the Rad6-HMD interaction and H2BK123 ubiquitylation but not other Rad6 functions. By employing RNA-sequencing as a sensitive approach for comparing mutant phenotypes, we show that mutating either side of the proposed Rad6-HMD interface yields strikingly similar transcriptome profiles that extensively overlap with those of a mutant that lacks the site of ubiquitylation in H2B. Our results fit a model in which a specific interface between a transcription elongation factor and a ubiquitin conjugase guides substrate selection toward a highly conserved chromatin target during active gene expression.
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Affiliation(s)
- Tasniem Fetian
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA15260
| | - Brendan M. McShane
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA15260
| | - Nicole L. Horan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA15260
| | - Donya N. Shodja
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA15260
| | - Jason D. True
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN46202
| | - Amber L. Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN46202
| | - Karen M. Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA15260
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7
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Langenbacher AD, Lu F, Crisman L, Huang ZYS, Chapski DJ, Vondriska TM, Wang Y, Gao C, Chen JN. Rtf1 Transcriptionally Regulates Neonatal and Adult Cardiomyocyte Biology. J Cardiovasc Dev Dis 2023; 10:221. [PMID: 37233188 PMCID: PMC10219292 DOI: 10.3390/jcdd10050221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/16/2023] [Accepted: 05/18/2023] [Indexed: 05/27/2023] Open
Abstract
The PAF1 complex component Rtf1 is an RNA Polymerase II-interacting transcription regulatory protein that promotes transcription elongation and the co-transcriptional monoubiquitination of histone 2B. Rtf1 plays an essential role in the specification of cardiac progenitors from the lateral plate mesoderm during early embryogenesis, but its requirement in mature cardiac cells is unknown. Here, we investigate the importance of Rtf1 in neonatal and adult cardiomyocytes using knockdown and knockout approaches. We demonstrate that loss of Rtf1 activity in neonatal cardiomyocytes disrupts cell morphology and results in a breakdown of sarcomeres. Similarly, Rtf1 ablation in mature cardiomyocytes of the adult mouse heart leads to myofibril disorganization, disrupted cell-cell junctions, fibrosis, and systolic dysfunction. Rtf1 knockout hearts eventually fail and exhibit structural and gene expression defects resembling dilated cardiomyopathy. Intriguingly, we observed that loss of Rtf1 activity causes a rapid change in the expression of key cardiac structural and functional genes in both neonatal and adult cardiomyocytes, suggesting that Rtf1 is continuously required to support expression of the cardiac gene program.
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Affiliation(s)
- Adam D Langenbacher
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90025, USA
| | - Fei Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90025, USA
| | - Lauren Crisman
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90025, USA
| | - Zi Yi Stephanie Huang
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90025, USA
| | - Douglas J Chapski
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90025, USA
| | - Thomas M Vondriska
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90025, USA
| | - Yibin Wang
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90025, USA
- Signature Research Program in Cardiovascular and Metabolic Diseases, Duke-NUS School of Medicine and National Heart Center of Singapore, Singapore 169857, Singapore
| | - Chen Gao
- Departments of Anesthesiology, Medicine, and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90025, USA
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jau-Nian Chen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90025, USA
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8
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Kujirai T, Ehara H, Sekine SI, Kurumizaka H. Structural Transition of the Nucleosome during Transcription Elongation. Cells 2023; 12:1388. [PMID: 37408222 DOI: 10.3390/cells12101388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 07/07/2023] Open
Abstract
In eukaryotes, genomic DNA is tightly wrapped in chromatin. The nucleosome is a basic unit of chromatin, but acts as a barrier to transcription. To overcome this impediment, the RNA polymerase II elongation complex disassembles the nucleosome during transcription elongation. After the RNA polymerase II passage, the nucleosome is rebuilt by transcription-coupled nucleosome reassembly. Nucleosome disassembly-reassembly processes play a central role in preserving epigenetic information, thus ensuring transcriptional fidelity. The histone chaperone FACT performs key functions in nucleosome disassembly, maintenance, and reassembly during transcription in chromatin. Recent structural studies of transcribing RNA polymerase II complexed with nucleosomes have provided structural insights into transcription elongation on chromatin. Here, we review the structural transitions of the nucleosome during transcription.
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Affiliation(s)
- 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
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Haruhiko Ehara
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Shun-Ichi Sekine
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, 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
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
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9
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Chen JJ, Stermer D, Tanny JC. Decoding histone ubiquitylation. Front Cell Dev Biol 2022; 10:968398. [PMID: 36105353 PMCID: PMC9464978 DOI: 10.3389/fcell.2022.968398] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Histone ubiquitylation is a critical part of both active and repressed transcriptional states, and lies at the heart of DNA damage repair signaling. The histone residues targeted for ubiquitylation are often highly conserved through evolution, and extensive functional studies of the enzymes that catalyze the ubiquitylation and de-ubiquitylation of histones have revealed key roles linked to cell growth and division, development, and disease in model systems ranging from yeast to human cells. Nonetheless, the downstream consequences of these modifications have only recently begun to be appreciated on a molecular level. Here we review the structure and function of proteins that act as effectors or “readers” of histone ubiquitylation. We highlight lessons learned about how ubiquitin recognition lends specificity and function to intermolecular interactions in the context of transcription and DNA repair, as well as what this might mean for how we think about histone modifications more broadly.
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10
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Ehara H, Kujirai T, Shirouzu M, Kurumizaka H, Sekine SI. Structural basis of nucleosome disassembly and reassembly by RNAPII elongation complex with FACT. Science 2022; 377:eabp9466. [PMID: 35981082 DOI: 10.1126/science.abp9466] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
During gene transcription, RNA polymerase II (RNAPII) traverses nucleosomes in chromatin, but its mechanism has remained elusive. Using cryo-electron microscopy, we obtained structures of the RNAPII elongation complex (EC) passing through a nucleosome, in the presence of transcription elongation factors Spt6, Spn1, Elf1, Spt4/5, and Paf1C and the histone chaperone FACT. The structures show snapshots of EC progression on DNA, mediating downstream nucleosome disassembly followed by its reassembly upstream of the EC, facilitated by FACT. FACT dynamically adapts to successively occurring subnucleosome intermediates, forming an interface with the EC. Spt6, Spt4/5, and Paf1C form a "cradle" at the EC DNA-exit site, and support the upstream nucleosome reassembly. These structures explain the mechanism by which the EC traverses nucleosomes while maintaining the chromatin structure and epigenetic information.
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Affiliation(s)
- Haruhiko Ehara
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Tomoya Kujirai
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama 230-0045, Japan.,Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Mikako Shirouzu
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Hitoshi Kurumizaka
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama 230-0045, Japan.,Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Shun-Ichi Sekine
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama 230-0045, Japan
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11
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Heldrich J, Milano CR, Markowitz TE, Ur S, Vale-Silva L, Corbett K, Hochwagen A. Two pathways drive meiotic chromosome axis assembly in Saccharomyces cerevisiae. Nucleic Acids Res 2022; 50:4545-4556. [PMID: 35412621 PMCID: PMC9071447 DOI: 10.1093/nar/gkac227] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/18/2022] [Accepted: 03/24/2022] [Indexed: 12/16/2022] Open
Abstract
Successful meiotic recombination, and thus fertility, depends on conserved axis proteins that organize chromosomes into arrays of anchored chromatin loops and provide a protected environment for DNA exchange. Here, we show that the stereotypic chromosomal distribution of axis proteins in Saccharomyces cerevisiae is the additive result of two independent pathways: a cohesin-dependent pathway, which was previously identified and mediates focal enrichment of axis proteins at gene ends, and a parallel cohesin-independent pathway that recruits axis proteins to broad genomic islands with high gene density. These islands exhibit elevated markers of crossover recombination as well as increased nucleosome density, which we show is a direct consequence of the underlying DNA sequence. A predicted PHD domain in the center of the axis factor Hop1 specifically mediates cohesin-independent axis recruitment. Intriguingly, other chromosome organizers, including cohesin, condensin, and topoisomerases, are differentially depleted from the same regions even in non-meiotic cells, indicating that these DNA sequence-defined chromatin islands exert a general influence on the patterning of chromosome structure.
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Affiliation(s)
- Jonna Heldrich
- Department of Biology, New York University, New York, NY 10003, USA
| | - Carolyn R Milano
- Department of Biology, New York University, New York, NY 10003, USA
| | | | - Sarah N Ur
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Kevin D Corbett
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
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12
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Wang Z, Song A, Xu H, Hu S, Tao B, Peng L, Wang J, Li J, Yu J, Wang L, Li Z, Chen X, Wang M, Chi Y, Wu J, Xu Y, Zheng H, Chen FX. Coordinated regulation of RNA polymerase II pausing and elongation progression by PAF1. SCIENCE ADVANCES 2022; 8:eabm5504. [PMID: 35363521 PMCID: PMC11093130 DOI: 10.1126/sciadv.abm5504] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Pleiotropic transcription regulator RNA polymerase II (Pol II)-associated factor 1 (PAF1) governs multiple transcriptional steps and the deposition of several epigenetic marks. However, it remains unclear how ultimate transcriptional outcome is determined by PAF1 and whether it relates to PAF1-controlled epigenetic marks. We use rapid degradation systems and reveal direct PAF1 functions in governing pausing partially by recruiting Integrator-PP2A (INTAC), in addition to ensuring elongation. Following acute PAF1 degradation, most destabilized polymerase undergoes effective release, which presumably relies on skewed balance between INTAC and P-TEFb, resulting in hyperphosphorylated substrates including SPT5. Impaired Pol II progression during elongation, along with altered pause release frequency, determines the final transcriptional outputs. Moreover, PAF1 degradation causes a cumulative decline in histone modifications. These epigenetic alterations in chromatin likely further influence the production of transcripts from PAF1 target genes.
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Affiliation(s)
- Zhenning Wang
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Aixia Song
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Hao Xu
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Shibin Hu
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Bolin Tao
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Linna Peng
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Jingwen Wang
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Radiation Oncology, Shanghai, China
| | - Jiabei Li
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Jiali Yu
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Li Wang
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Ze Li
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Xizi Chen
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Mengyun Wang
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Radiation Oncology, Shanghai, China
| | - Yayun Chi
- Department of Breast Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Jiong Wu
- Department of Breast Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Hai Zheng
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Fei Xavier Chen
- Fudan University Shanghai Cancer Center, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Radiation Oncology, Shanghai, China
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13
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Francette AM, Tripplehorn SA, Arndt KM. The Paf1 Complex: A Keystone of Nuclear Regulation Operating at the Interface of Transcription and Chromatin. J Mol Biol 2021; 433:166979. [PMID: 33811920 PMCID: PMC8184591 DOI: 10.1016/j.jmb.2021.166979] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/21/2021] [Accepted: 03/24/2021] [Indexed: 12/14/2022]
Abstract
The regulation of transcription by RNA polymerase II is closely intertwined with the regulation of chromatin structure. A host of proteins required for the disassembly, reassembly, and modification of nucleosomes interacts with Pol II to aid its movement and counteract its disruptive effects on chromatin. The highly conserved Polymerase Associated Factor 1 Complex, Paf1C, travels with Pol II and exerts control over transcription elongation and chromatin structure, while broadly impacting the transcriptome in both single cell and multicellular eukaryotes. Recent studies have yielded exciting new insights into the mechanisms by which Paf1C regulates transcription elongation, epigenetic modifications, and post-transcriptional steps in eukaryotic gene expression. Importantly, these functional studies are now supported by an extensive foundation of high-resolution structural information, providing intimate views of Paf1C and its integration into the larger Pol II elongation complex. As a global regulatory factor operating at the interface between chromatin and transcription, the impact of Paf1C is broad and its influence reverberates into other domains of nuclear regulation, including genome stability, telomere maintenance, and DNA replication.
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Affiliation(s)
- Alex M Francette
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Sarah A Tripplehorn
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States.
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14
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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 PMCID: PMC8989640 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] [Track Full Text] [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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15
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16
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Farr SE, Woods EJ, Joseph JA, Garaizar A, Collepardo-Guevara R. Nucleosome plasticity is a critical element of chromatin liquid-liquid phase separation and multivalent nucleosome interactions. Nat Commun 2021; 12:2883. [PMID: 34001913 PMCID: PMC8129070 DOI: 10.1038/s41467-021-23090-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/23/2021] [Indexed: 12/19/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) is an important mechanism that helps explain the membraneless compartmentalization of the nucleus. Because chromatin compaction and LLPS are collective phenomena, linking their modulation to the physicochemical features of nucleosomes is challenging. Here, we develop an advanced multiscale chromatin model-integrating atomistic representations, a chemically-specific coarse-grained model, and a minimal model-to resolve individual nucleosomes within sub-Mb chromatin domains and phase-separated systems. To overcome the difficulty of sampling chromatin at high resolution, we devise a transferable enhanced-sampling Debye-length replica-exchange molecular dynamics approach. We find that nucleosome thermal fluctuations become significant at physiological salt concentrations and destabilize the 30-nm fiber. Our simulations show that nucleosome breathing favors stochastic folding of chromatin and promotes LLPS by simultaneously boosting the transient nature and heterogeneity of nucleosome-nucleosome contacts, and the effective nucleosome valency. Our work puts forward the intrinsic plasticity of nucleosomes as a key element in the liquid-like behavior of nucleosomes within chromatin, and the regulation of chromatin LLPS.
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Affiliation(s)
- Stephen E Farr
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Esmae J Woods
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Jerelle A Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
- Department of Genetics, University of Cambridge, Cambridge, UK.
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17
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Viktorovskaya O, Chuang J, Jain D, Reim NI, López-Rivera F, Murawska M, Spatt D, Churchman LS, Park PJ, Winston F. Essential histone chaperones collaborate to regulate transcription and chromatin integrity. Genes Dev 2021; 35:698-712. [PMID: 33888559 PMCID: PMC8091981 DOI: 10.1101/gad.348431.121] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/30/2021] [Indexed: 12/15/2022]
Abstract
Histone chaperones are critical for controlling chromatin integrity during transcription, DNA replication, and DNA repair. Three conserved and essential chaperones, Spt6, Spn1/Iws1, and FACT, associate with elongating RNA polymerase II and interact with each other physically and/or functionally; however, there is little understanding of their individual functions or their relationships with each other. In this study, we selected for suppressors of a temperature-sensitive spt6 mutation that disrupts the Spt6-Spn1 physical interaction and that also causes both transcription and chromatin defects. This selection identified novel mutations in FACT. Surprisingly, suppression by FACT did not restore the Spt6-Spn1 interaction, based on coimmunoprecipitation, ChIP, and mass spectrometry experiments. Furthermore, suppression by FACT bypassed the complete loss of Spn1. Interestingly, the FACT suppressor mutations cluster along the FACT-nucleosome interface, suggesting that they alter FACT-nucleosome interactions. In agreement with this observation, we showed that the spt6 mutation that disrupts the Spt6-Spn1 interaction caused an elevated level of FACT association with chromatin, while the FACT suppressors reduced the level of FACT-chromatin association, thereby restoring a normal Spt6-FACT balance on chromatin. Taken together, these studies reveal previously unknown regulation between histone chaperones that is critical for their essential in vivo functions.
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Affiliation(s)
- Olga Viktorovskaya
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - James Chuang
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Dhawal Jain
- Department of Biomedical Informatics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Natalia I Reim
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Francheska López-Rivera
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Magdalena Murawska
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Dan Spatt
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - L Stirling Churchman
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Peter J Park
- Department of Biomedical Informatics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Fred Winston
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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18
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Bhargava P. Regulatory networking of the three RNA polymerases helps the eukaryotic cells cope with environmental stress. Curr Genet 2021; 67:595-603. [PMID: 33778898 DOI: 10.1007/s00294-021-01179-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 01/25/2023]
Abstract
Environmental stress influences the cellular physiology in multiple ways. Transcription by all the three RNA polymerases (Pols I, II, or III) in eukaryotes is a highly regulated process. With latest advances in technology, which have made many extensive genome-wide studies possible, it is increasingly recognized that all the cellular processes may be interconnected. A comprehensive view of the current research observations brings forward an interesting possibility that Pol II-associated factors may be directly involved in the regulation of expression from the Pol III-transcribed genes and vice versa, thus enabling a cross-talk between the two polymerases. An equally important cross-talk between the Pol I and Pol II/III has also been documented. Collectively, these observations lead to a change in the current perception that looks at the transcription of a set of genes transcribed by the three Pols in isolation. Emergence of an inclusive perspective underscores that all stress signals may converge on common mechanisms of transcription regulation, requiring an extensive cross-talk between the regulatory partners. Of the three RNA polymerases, Pol III turns out as the hub of these cross-talks, an essential component of the cellular stress-response under which the majority of the cellular transcriptional activity is shut down or re-aligned.
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Affiliation(s)
- Purnima Bhargava
- Centre for Cellular and Molecular Biology, (Council of Scientific and Industrial Research), Uppal Road, Hyderabad, 500007, India.
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19
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Formosa T, Winston F. The role of FACT in managing chromatin: disruption, assembly, or repair? Nucleic Acids Res 2020; 48:11929-11941. [PMID: 33104782 PMCID: PMC7708052 DOI: 10.1093/nar/gkaa912] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/20/2022] Open
Abstract
FACT (FAcilitates Chromatin Transcription) has long been considered to be a transcription elongation factor whose ability to destabilize nucleosomes promotes RNAPII progression on chromatin templates. However, this is just one function of this histone chaperone, as FACT also functions in DNA replication. While broadly conserved among eukaryotes and essential for viability in many organisms, dependence on FACT varies widely, with some differentiated cells proliferating normally in its absence. It is therefore unclear what the core functions of FACT are, whether they differ in different circumstances, and what makes FACT essential in some situations but not others. Here, we review recent advances and propose a unifying model for FACT activity. By analogy to DNA repair, we propose that the ability of FACT to both destabilize and assemble nucleosomes allows it to monitor and restore nucleosome integrity as part of a system of chromatin repair, in which disruptions in the packaging of DNA are sensed and returned to their normal state. The requirement for FACT then depends on the level of chromatin disruption occurring in the cell, and the cell's ability to tolerate packaging defects. The role of FACT in transcription would then be just one facet of a broader system for maintaining chromatin integrity.
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Affiliation(s)
- Tim Formosa
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Fred Winston
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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20
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Histone chaperone FACT FAcilitates Chromatin Transcription: mechanistic and structural insights. Curr Opin Struct Biol 2020; 65:26-32. [DOI: 10.1016/j.sbi.2020.05.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/12/2020] [Accepted: 05/28/2020] [Indexed: 12/31/2022]
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21
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Hainer SJ, Kaplan CD. Specialized RSC: Substrate Specificities for a Conserved Chromatin Remodeler. Bioessays 2020; 42:e2000002. [PMID: 32490565 PMCID: PMC7329613 DOI: 10.1002/bies.202000002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/11/2020] [Indexed: 01/16/2023]
Abstract
The remodel the structure of chromatin (RSC) nucleosome remodeling complex is a conserved chromatin regulator with roles in chromatin organization, especially over nucleosome depleted regions therefore functioning in gene expression. Recent reports in Saccharomyces cerevisiae have identified specificities in RSC activity toward certain types of nucleosomes. RSC has now been shown to preferentially evict nucleosomes containing the histone variant H2A.Z in vitro. Furthermore, biochemical activities of distinct RSC complexes has been found to differ when their nucleosome substrate is partially unraveled. Mammalian BAF complexes, the homologs of yeast RSC and SWI/SNF complexes, are also linked to nucleosomes with H2A.Z, but this relationship may be complex and extent of conservation remains to be determined. The interplay of remodelers with specific nucleosome substrates and regulation of remodeler outcomes by nucleosome composition are tantalizing questions given the wave of structural data emerging for RSC and other SWI/SNF family remodelers.
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Affiliation(s)
- Sarah J Hainer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
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22
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Abstract
In eukaryotes, DNA is highly compacted within the nucleus into a structure known as chromatin. Modulation of chromatin structure allows for precise regulation of gene expression, and thereby controls cell fate decisions. Specific chromatin organization is established and preserved by numerous factors to generate desired cellular outcomes. In embryonic stem (ES) cells, chromatin is precisely regulated to preserve their two defining characteristics: self-renewal and pluripotent state. This action is accomplished by a litany of nucleosome remodelers, histone variants, epigenetic marks, and other chromatin regulatory factors. These highly dynamic regulatory factors come together to precisely define a chromatin state that is conducive to ES cell maintenance and development, where dysregulation threatens the survival and fitness of the developing organism.
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Affiliation(s)
- David C Klein
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Sarah J Hainer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States.
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23
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Campbell JB, Edwards MJ, Ozersky SA, Duina AA. Evidence that dissociation of Spt16 from transcribed genes is partially dependent on RNA Polymerase II termination. Transcription 2019; 10:195-206. [PMID: 31809228 PMCID: PMC6948958 DOI: 10.1080/21541264.2019.1685837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
FACT (FAcilitates Chromatin Transactions) is a highly conserved histone chaperone complex in eukaryotic cells that can interact and manipulate nucleosomes in order to promote a variety of DNA-based processes and to maintain the integrity of chromatin throughout the genome. Whereas key features of the physical interactions that occur between FACT and nucleosomes in vitro have been elucidated in recent years, less is known regarding FACT functional dynamics in vivo. Using the Saccharomyces cerevisiae system, we now provide evidence that at least at some genes dissociation of the FACT subunit Spt16 from their 3′ ends is partially dependent on RNA Polymerase II (Pol II) termination. Combined with other studies, our results are consistent with a two-phase mechanism for FACT dissociation from genes, one that occurs upstream from Pol II dissociation and is Pol II termination-independent and the other that occurs further downstream and is dependent on Pol II termination.
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Affiliation(s)
| | | | | | - Andrea A Duina
- Biology Department, Hendrix College, Conway, Arkansas, USA
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