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Banko P, Okimune KI, Nagy SK, Hamasaki A, Morishita R, Onouchi H, Takasuka TE. In vitro co-expression chromatin assembly and remodeling platform for plant histone variants. Sci Rep 2024; 14:936. [PMID: 38195981 PMCID: PMC10776871 DOI: 10.1038/s41598-024-51460-6] [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: 05/03/2023] [Accepted: 01/05/2024] [Indexed: 01/11/2024] Open
Abstract
Histone variants play a central role in shaping the chromatin landscape in plants, yet, how their distinct combinations affect nucleosome properties and dynamics is still largely elusive. To address this, we developed a novel chromatin assembly platform for Arabidopsis thaliana, using wheat germ cell-free protein expression. Four canonical histones and five reported histone variants were used to assemble twelve A. thaliana nucleosome combinations. Seven combinations were successfully reconstituted and confirmed by supercoiling and micrococcal nuclease (MNase) assays. The effect of the remodeling function of the CHR11-DDR4 complex on these seven combinations was evaluated based on the nucleosome repeat length and nucleosome spacing index obtained from the MNase ladders. Overall, the current study provides a novel method to elucidate the formation and function of a diverse range of nucleosomes in plants.
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Affiliation(s)
- Petra Banko
- Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Kei-Ichi Okimune
- Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
- Graduate School of Global Food Resources, Hokkaido University, Sapporo, 060-0809, Japan
| | - Szilvia K Nagy
- Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
- Department of Molecular Biology, Institute of Biochemistry and Molecular Biology, Semmelweis University, Budapest, 1094, Hungary
| | | | - Ryo Morishita
- CellFree Sciences Co., Ltd, Matsuyama, 790-8577, Japan
| | - Hitoshi Onouchi
- Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Taichi E Takasuka
- Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
- Graduate School of Global Food Resources, Hokkaido University, Sapporo, 060-0809, Japan.
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2
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Bomber ML, Wang J, Liu Q, Barnett KR, Layden HM, Hodges E, Stengel KR, Hiebert SW. Human SMARCA5 is continuously required to maintain nucleosome spacing. Mol Cell 2023; 83:507-522.e6. [PMID: 36630954 PMCID: PMC9974918 DOI: 10.1016/j.molcel.2022.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 12/07/2022] [Accepted: 12/16/2022] [Indexed: 01/12/2023]
Abstract
Genetic models suggested that SMARCA5 was required for DNA-templated events including transcription, DNA replication, and DNA repair. We engineered a degron tag into the endogenous alleles of SMARCA5, a catalytic component of the imitation switch complexes in three different human cell lines to define the effects of rapid degradation of this key regulator. Degradation of SMARCA5 was associated with a rapid increase in global nucleosome repeat length, which may allow greater chromatin compaction. However, there were few changes in nascent transcription within the first 6 h of degradation. Nevertheless, we demonstrated a requirement for SMARCA5 to control nucleosome repeat length at G1/S and during the S phase. SMARCA5 co-localized with CTCF and H2A.Z, and we found a rapid loss of CTCF DNA binding and disruption of nucleosomal phasing around CTCF binding sites. This spatiotemporal analysis indicates that SMARCA5 is continuously required for maintaining nucleosomal spacing.
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Affiliation(s)
- Monica L Bomber
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jing Wang
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Qi Liu
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kelly R Barnett
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Hillary M Layden
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Emily Hodges
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kristy R Stengel
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA.
| | - Scott W Hiebert
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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3
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Bhat JA, Balliano AJ, Hayes JJ. Histone protein surface accessibility dictates direction of RSC-dependent nucleosome mobilization. Nucleic Acids Res 2022; 50:10376-10384. [PMID: 36161493 PMCID: PMC9561379 DOI: 10.1093/nar/gkac790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/23/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022] Open
Abstract
Chromatin remodeling enzymes use energy derived from ATP hydrolysis to mobilize nucleosomes and alter their structure to facilitate DNA access. The Remodels the Structure of Chromatin (RSC) complex has been extensively studied, yet aspects of how this complex functionally interacts with nucleosomes remain unclear. We introduce a steric mapping approach to determine how RSC activity depends on interaction with specific surfaces within the nucleosome. We find that blocking SHL + 4.5/–4.5 via streptavidin binding to the H2A N-terminal tail domains results in inhibition of RSC nucleosome mobilization. However, restriction enzyme assays indicate that remodeling-dependent exposure of an internal DNA site near the nucleosome dyad is not affected. In contrast, occlusion of both protein faces of the nucleosome by streptavidin attachment near the acidic patch completely blocks both remodeling-dependent nucleosome mobilization and internal DNA site exposure. However, we observed partial inhibition when only one protein surface is occluded, consistent with abrogation of one of two productive RSC binding orientations. Our results indicate that nucleosome mobilization requires RSC access to the trailing but not the leading protein surface, and reveals a mechanism by which RSC and related complexes may drive unidirectional movement of nucleosomes to regulate cis-acting DNA sequences in vivo.
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Affiliation(s)
- Javeed Ahmad Bhat
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Angela J Balliano
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jeffrey J Hayes
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA
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4
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Hannan Parker A, Wilkinson SW, Ton J. Epigenetics: a catalyst of plant immunity against pathogens. THE NEW PHYTOLOGIST 2022; 233:66-83. [PMID: 34455592 DOI: 10.1111/nph.17699] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/20/2021] [Indexed: 05/11/2023]
Abstract
The plant immune system protects against pests and diseases. The recognition of stress-related molecular patterns triggers localised immune responses, which are often followed by longer-lasting systemic priming and/or up-regulation of defences. In some cases, this induced resistance (IR) can be transmitted to following generations. Such transgenerational IR is gradually reversed in the absence of stress at a rate that is proportional to the severity of disease experienced in previous generations. This review outlines the mechanisms by which epigenetic responses to pathogen infection shape the plant immune system across expanding time scales. We review the cis- and trans-acting mechanisms by which stress-inducible epigenetic changes at transposable elements (TEs) regulate genome-wide defence gene expression and draw particular attention to one regulatory model that is supported by recent evidence about the function of AGO1 and H2A.Z in transcriptional control of defence genes. Additionally, we explore how stress-induced mobilisation of epigenetically controlled TEs acts as a catalyst of Darwinian evolution by generating (epi)genetic diversity at environmentally responsive genes. This raises questions about the long-term evolutionary consequences of stress-induced diversification of the plant immune system in relation to the long-held dichotomy between Darwinian and Lamarckian evolution.
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Affiliation(s)
- Adam Hannan Parker
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
| | - Samuel W Wilkinson
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jurriaan Ton
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
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5
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Clapier CR. Sophisticated Conversations between Chromatin and Chromatin Remodelers, and Dissonances in Cancer. Int J Mol Sci 2021; 22:5578. [PMID: 34070411 PMCID: PMC8197500 DOI: 10.3390/ijms22115578] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 01/13/2023] Open
Abstract
The establishment and maintenance of genome packaging into chromatin contribute to define specific cellular identity and function. Dynamic regulation of chromatin organization and nucleosome positioning are critical to all DNA transactions-in particular, the regulation of gene expression-and involve the cooperative action of sequence-specific DNA-binding factors, histone modifying enzymes, and remodelers. Remodelers are molecular machines that generate various chromatin landscapes, adjust nucleosome positioning, and alter DNA accessibility by using ATP binding and hydrolysis to perform DNA translocation, which is highly regulated through sophisticated structural and functional conversations with nucleosomes. In this review, I first present the functional and structural diversity of remodelers, while emphasizing the basic mechanism of DNA translocation, the common regulatory aspects, and the hand-in-hand progressive increase in complexity of the regulatory conversations between remodelers and nucleosomes that accompanies the increase in challenges of remodeling processes. Next, I examine how, through nucleosome positioning, remodelers guide the regulation of gene expression. Finally, I explore various aspects of how alterations/mutations in remodelers introduce dissonance into the conversations between remodelers and nucleosomes, modify chromatin organization, and contribute to oncogenesis.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences & Howard Hughes Medical Institute, Huntsman Cancer Institute, University of Utah School of Medicine, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
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6
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Li D, Wang Q, Gong NN, Kurolap A, Feldman HB, Boy N, Brugger M, Grand K, McWalter K, Guillen Sacoto MJ, Wakeling E, Hurst J, March ME, Bhoj EJ, Nowaczyk MJM, Gonzaga-Jauregui C, Mathew M, Dava-Wala A, Siemon A, Bartholomew D, Huang Y, Lee H, Martinez-Agosto JA, Schwaibold EMC, Brunet T, Choukair D, Pais LS, White SM, Christodoulou J, Brown D, Lindstrom K, Grebe T, Tiosano D, Kayser MS, Tan TY, Deardorff MA, Song Y, Hakonarson H. Pathogenic variants in SMARCA5, a chromatin remodeler, cause a range of syndromic neurodevelopmental features. SCIENCE ADVANCES 2021; 7:7/20/eabf2066. [PMID: 33980485 PMCID: PMC8115915 DOI: 10.1126/sciadv.abf2066] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 03/23/2021] [Indexed: 05/17/2023]
Abstract
Intellectual disability encompasses a wide spectrum of neurodevelopmental disorders, with many linked genetic loci. However, the underlying molecular mechanism for more than 50% of the patients remains elusive. We describe pathogenic variants in SMARCA5, encoding the ATPase motor of the ISWI chromatin remodeler, as a cause of a previously unidentified neurodevelopmental disorder, identifying 12 individuals with de novo or dominantly segregating rare heterozygous variants. Accompanying phenotypes include mild developmental delay, frequent postnatal short stature and microcephaly, and recurrent dysmorphic features. Loss of function of the SMARCA5 Drosophila ortholog Iswi led to smaller body size, reduced sensory dendrite complexity, and tiling defects in larvae. In adult flies, Iswi neural knockdown caused decreased brain size, aberrant mushroom body morphology, and abnormal locomotor function. Iswi loss of function was rescued by wild-type but not mutant SMARCA5. Our results demonstrate that SMARCA5 pathogenic variants cause a neurodevelopmental syndrome with mild facial dysmorphia.
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Affiliation(s)
- Dong Li
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
| | - Qin Wang
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Naihua N Gong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alina Kurolap
- The Genetics Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Hagit Baris Feldman
- The Genetics Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nikolas Boy
- Division of Child Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Melanie Brugger
- Institute of Human Genetics, Technical University Munich, Munich, Germany
- Institute of Human Genetics, University Hospital LMU Munich, Goethestr. 29, Munich, Germany
| | - Katheryn Grand
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | | | | | - Emma Wakeling
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Jane Hurst
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Michael E March
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elizabeth J Bhoj
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Małgorzata J M Nowaczyk
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | | | - Mariam Mathew
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Ashita Dava-Wala
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Amy Siemon
- Department of Pediatrics and Clinical Genetics, Nationwide Children's Hospital, Columbus, OH, USA
| | - Dennis Bartholomew
- Department of Pediatrics and Clinical Genetics, Nationwide Children's Hospital, Columbus, OH, USA
| | - Yue Huang
- Department of Human Genetics; Division of Medical Genetics, Department of Pediatrics; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Hane Lee
- Department of Pathology and Laboratory Medicine; Department of Human Genetics; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Julian A Martinez-Agosto
- Department of Human Genetics; Division of Medical Genetics, Department of Pediatrics; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Eva M C Schwaibold
- Department of Pathology and Laboratory Medicine; Department of Human Genetics; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Theresa Brunet
- Institute of Human Genetics, Technical University Munich, Munich, Germany
| | - Daniela Choukair
- Division of Paediatric Endocrinology and Diabetes, Department of Paediatrics, University Hospital Heidelberg, Heidelberg, Germany
| | - Lynn S Pais
- Broad Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | - Susan M White
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - John Christodoulou
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Dana Brown
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Kristin Lindstrom
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Theresa Grebe
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, AZ, USA
- College of Medicine, University of Arizona, Phoenix, 475 N. 5th Street, Phoenix, AZ, USA
| | - Dov Tiosano
- Pediatric Endocrinology Unit, Ruth Rappaport Children's Hospital, Rambam Healthcare Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel
| | - Matthew S Kayser
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Tiong Yang Tan
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Matthew A Deardorff
- Departments of Pathology and Pediatrics, Children's Hospital Los Angeles, and University of Southern California, Los Angeles, CA, USA
| | - Yuanquan Song
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
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7
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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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8
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Nucleosome Positioning and Spacing: From Mechanism to Function. J Mol Biol 2021; 433:166847. [PMID: 33539878 DOI: 10.1016/j.jmb.2021.166847] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 01/16/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023]
Abstract
Eukaryotes associate their genomes with histone proteins, forming nucleosome particles. Nucleosomes regulate and protect the genetic information. They often assemble into evenly spaced arrays of nucleosomes. These regular nucleosome arrays cover significant portions of the genome, in particular over genes. The presence of these evenly spaced nucleosome arrays is highly conserved throughout the entire eukaryotic domain. Here, we review the mechanisms behind the establishment of this primary structure of chromatin with special emphasis on the biogenesis of evenly spaced nucleosome arrays. We highlight the roles that transcription, nucleosome remodelers, DNA sequence, and histone density play towards the formation of evenly spaced nucleosome arrays and summarize our current understanding of their cellular functions. We end with key unanswered questions that remain to be explored to obtain an in-depth understanding of the biogenesis and function of the nucleosome landscape.
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9
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Lehmann LC, Bacic L, Hewitt G, Brackmann K, Sabantsev A, Gaullier G, Pytharopoulou S, Degliesposti G, Okkenhaug H, Tan S, Costa A, Skehel JM, Boulton SJ, Deindl S. Mechanistic Insights into Regulation of the ALC1 Remodeler by the Nucleosome Acidic Patch. Cell Rep 2020; 33:108529. [PMID: 33357431 PMCID: PMC7116876 DOI: 10.1016/j.celrep.2020.108529] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/08/2020] [Accepted: 11/24/2020] [Indexed: 01/09/2023] Open
Abstract
Upon DNA damage, the ALC1/CHD1L nucleosome remodeling enzyme (remodeler) is activated by binding to poly(ADP-ribose). How activated ALC1 recognizes the nucleosome, as well as how this recognition is coupled to remodeling, is unknown. Here, we show that remodeling by ALC1 requires a wild-type acidic patch on the entry side of the nucleosome. The cryo-electron microscopy structure of a nucleosome-ALC1 linker complex reveals a regulatory linker segment that binds to the acidic patch. Mutations within this interface alter the dynamics of ALC1 recruitment to DNA damage and impede the ATPase and remodeling activities of ALC1. Full activation requires acidic patch-linker segment interactions that tether the remodeler to the nucleosome and couple ATP hydrolysis to nucleosome mobilization. Upon DNA damage, such a requirement may be used to modulate ALC1 activity via changes in the nucleosome acidic patches.
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Affiliation(s)
- Laura C Lehmann
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Luka Bacic
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Graeme Hewitt
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Klaus Brackmann
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Anton Sabantsev
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Guillaume Gaullier
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Sofia Pytharopoulou
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden
| | - Gianluca Degliesposti
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | | | - Song Tan
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Alessandro Costa
- Macromolecular Machines Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - J Mark Skehel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Simon J Boulton
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
| | - Sebastian Deindl
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75124 Uppsala, Sweden.
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10
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Bhardwaj SK, Hailu SG, Olufemi L, Brahma S, Kundu S, Hota SK, Persinger J, Bartholomew B. Dinucleosome specificity and allosteric switch of the ISW1a ATP-dependent chromatin remodeler in transcription regulation. Nat Commun 2020; 11:5913. [PMID: 33219211 PMCID: PMC7680125 DOI: 10.1038/s41467-020-19700-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/27/2020] [Indexed: 01/22/2023] Open
Abstract
Over the last 3 decades ATP-dependent chromatin remodelers have been thought to recognize chromatin at the level of single nucleosomes rather than higher-order organization of more than one nucleosome. We show the yeast ISW1a remodeler has such higher-order structural specificity, as manifested by large allosteric changes that activate the nucleosome remodeling and spacing activities of ISW1a when bound to dinucleosomes. Although the ATPase domain of Isw1 docks at the SHL2 position when ISW1a is bound to either mono- or di-nucleosomes, there are major differences in the interactions of the catalytic subunit Isw1 with the acidic pocket of nucleosomes and the accessory subunit Ioc3 with nucleosomal DNA. By mutational analysis and uncoupling of ISW1a's dinucleosome specificity, we find that dinucleosome recognition is required by ISW1a for proper chromatin organization at promoters; as well as transcription regulation in combination with the histone acetyltransferase NuA4 and histone H2A.Z exchanger SWR1.
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Affiliation(s)
- Saurabh K Bhardwaj
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA
- Worldwide Research and Development, Pfizer Inc, Houston, USA
| | - Solomon G Hailu
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA
- EpiCypher, Inc., Durham, USA
| | - Lola Olufemi
- National Institute of Neurological Disorders and Stroke, Bethesda, USA
| | - Sandipan Brahma
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, USA
| | - Soumyadipta Kundu
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA
- ZS Associates, Evanston, USA
| | - Swetansu K Hota
- University of California-San Francisco, Gladstone Institutes, San Francisco, USA
| | - Jim Persinger
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA
| | - Blaine Bartholomew
- The University of Texas MD Anderson Cancer Center, Department of Epigenetics & Molecular Carcinogenesis, Science Park, Smithville, TX, 78957, USA.
- Center for Cancer Epigenetics, MD Anderson Cancer Center, Houston, USA.
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11
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Genome-wide chromatin accessibility is restricted by ANP32E. Nat Commun 2020; 11:5063. [PMID: 33033242 PMCID: PMC7546623 DOI: 10.1038/s41467-020-18821-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 09/16/2020] [Indexed: 12/11/2022] Open
Abstract
Genome-wide chromatin state underlies gene expression potential and cellular function. Epigenetic features and nucleosome positioning contribute to the accessibility of DNA, but widespread regulators of chromatin state are largely unknown. Our study investigates how coordination of ANP32E and H2A.Z contributes to genome-wide chromatin state in mouse fibroblasts. We define H2A.Z as a universal chromatin accessibility factor, and demonstrate that ANP32E antagonizes H2A.Z accumulation to restrict chromatin accessibility genome-wide. In the absence of ANP32E, H2A.Z accumulates at promoters in a hierarchical manner. H2A.Z initially localizes downstream of the transcription start site, and if H2A.Z is already present downstream, additional H2A.Z accumulates upstream. This hierarchical H2A.Z accumulation coincides with improved nucleosome positioning, heightened transcription factor binding, and increased expression of neighboring genes. Thus, ANP32E dramatically influences genome-wide chromatin accessibility through subtle refinement of H2A.Z patterns, providing a means to reprogram chromatin state and to hone gene expression levels. Chromatin state underlies cellular function, and transcription factor binding patterns along with epigenetic marks define chromatin state. Here the authors show that the histone chaperone ANP32E functions through regulation of H2A.Z to restrict genome-wide chromatin accessibility and to inhibit gene transcriptional activation.
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12
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Olson NM, Kroc S, Johnson JA, Zahid H, Ycas PD, Chan A, Kimbrough JR, Kalra P, Schönbrunn E, Pomerantz WCK. NMR Analyses of Acetylated H2A.Z Isoforms Identify Differential Binding Interactions with the Bromodomain of the NURF Nucleosome Remodeling Complex. Biochemistry 2020; 59:1871-1880. [PMID: 32356653 DOI: 10.1021/acs.biochem.0c00159] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Gene specific recruitment of bromodomain-containing proteins to chromatin is affected by post-translational acetylation of lysine on histones. Whereas interactions of the bromodomain with acetylation patterns of native histones (H2A, H2B, H3, and H4) have been well characterized, the motif for recognition for histone variants H2A.Z I and H2A.Z II by bromodomains has yet to be fully investigated. Elucidating these molecular mechanisms is crucial for understanding transcriptional regulation in cellular processes involved in both development and disease. Here, we have used protein-observed fluorine NMR to fully characterize the affinities of H2A.Z I and II acetylation patterns for BPTF's bromodomain and found the diacetylated mark of lysine 7 and 13 on H2A.Z II to have the strongest interaction with K7ac preferentially engaging the binding site. We further examined the selectivity of H2A.Z histones against a variety of bromodomains, revealing that the bromodomain of CECR2 binds with the highest affinity and specificity for acetylated H2A.Z I over isoform II. These results support a possible role for different H2A.Z transcriptional activation mechanisms that involve recruitment of chromatin remodeling complexes.
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Affiliation(s)
- Noelle M Olson
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Samantha Kroc
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Jorden A Johnson
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Huda Zahid
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Peter D Ycas
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Alice Chan
- Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, Florida 33612, United States
| | - Jennifer R Kimbrough
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Prakriti Kalra
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Ernst Schönbrunn
- Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, Florida 33612, United States
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
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13
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Dao HT, Dul BE, Dann GP, Liszczak GP, Muir TW. A basic motif anchoring ISWI to nucleosome acidic patch regulates nucleosome spacing. Nat Chem Biol 2020; 16:134-142. [PMID: 31819269 PMCID: PMC6982587 DOI: 10.1038/s41589-019-0413-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 10/22/2019] [Indexed: 12/15/2022]
Abstract
Recent studies have implicated the nucleosome acidic patch in the activity of ATP-dependent chromatin remodeling machines. We used a photocrosslinking-based nucleosome profiling technology (photoscanning) to identify a conserved basic motif within the catalytic subunit of ISWI remodelers, SNF2h, which engages this nucleosomal epitope. This region of SNF2h is essential for chromatin remodeling activity in a reconstituted biochemical system and in cells. Our studies suggest that the basic motif in SNF2h plays a critical role in anchoring the remodeler to the nucleosomal surface. We also examine the functional consequences of several cancer-associated histone mutations that map to the nucleosome acidic patch. Kinetic studies using physiologically relevant heterotypic nucleosomal substrates ('Janus' nucleosomes) indicate that these cancer-associated mutations can disrupt regularly spaced chromatin structure by inducing ISWI-mediated unidirectional nucleosome sliding. These results indicate a potential mechanistic link between oncogenic histones and alterations to the chromatin landscape.
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Affiliation(s)
- Hai T Dao
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Barbara E Dul
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Geoffrey P Dann
- Department of Chemistry, Princeton University, Princeton, NJ, USA
- Department of Biochemistry and Biophysics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Glen P Liszczak
- Department of Chemistry, Princeton University, Princeton, NJ, USA
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Tom W Muir
- Department of Chemistry, Princeton University, Princeton, NJ, USA.
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14
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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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15
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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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16
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Cakiroglu A, Clapier CR, Ehrensberger AH, Darbo E, Cairns BR, Luscombe NM, Svejstrup JQ. Genome-wide reconstitution of chromatin transactions reveals that RSC preferentially disrupts H2AZ-containing nucleosomes. Genome Res 2019; 29:988-998. [PMID: 31097474 PMCID: PMC6581049 DOI: 10.1101/gr.243139.118] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 05/08/2019] [Indexed: 12/03/2022]
Abstract
Chromatin transactions are typically studied in vivo, or in vitro using artificial chromatin lacking the epigenetic complexity of the natural material. Attempting to bridge the gap between these approaches, we established a system for isolating the yeast genome as a library of mononucleosomes harboring the natural epigenetic signature, suitable for biochemical manipulation. Combined with deep sequencing, this library was used to investigate the stability of individual nucleosomes and, as proof of principle, the nucleosome preference of the chromatin remodeling complex, RSC. This approach uncovered a distinct preference of RSC for nucleosomes derived from regions with a high density of histone variant H2AZ, and this preference is indeed markedly diminished using nucleosomes from cells lacking H2AZ. The preference for H2AZ remodeling/nucleosome ejection can also be reconstituted with recombinant nucleosome arrays. Together, our data indicate that, despite being separated from their genomic context, individual nucleosomes can retain their original identity as promoter- or transcription start site (TSS)-nucleosomes. Besides shedding new light on substrate preference of the chromatin remodeler RSC, the simple experimental system outlined here should be generally applicable to the study of chromatin transactions.
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Affiliation(s)
- Aylin Cakiroglu
- Bioinformatics and Computational Biology Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Cedric R Clapier
- Department of Oncological Sciences, Huntsman Cancer Institute, and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Andreas H Ehrensberger
- Bioinformatics and Computational Biology Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Elodie Darbo
- Bioinformatics and Computational Biology Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Bradley R Cairns
- Department of Oncological Sciences, Huntsman Cancer Institute, and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Nicholas M Luscombe
- Bioinformatics and Computational Biology Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
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17
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Gamarra N, Johnson SL, Trnka MJ, Burlingame AL, Narlikar GJ. The nucleosomal acidic patch relieves auto-inhibition by the ISWI remodeler SNF2h. eLife 2018; 7:35322. [PMID: 29664398 PMCID: PMC5976439 DOI: 10.7554/elife.35322] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 04/16/2018] [Indexed: 12/12/2022] Open
Abstract
ISWI family chromatin remodeling motors use sophisticated autoinhibition mechanisms to control nucleosome sliding. Yet how the different autoinhibitory domains are regulated is not well understood. Here we show that an acidic patch formed by histones H2A and H2B of the nucleosome relieves the autoinhibition imposed by the AutoN and the NegC regions of the human ISWI remodeler SNF2h. Further, by single molecule FRET we show that the acidic patch helps control the distance travelled per translocation event. We propose a model in which the acidic patch activates SNF2h by providing a landing pad for the NegC and AutoN auto-inhibitory domains. Interestingly, the INO80 complex is also strongly dependent on the acidic patch for nucleosome sliding, indicating that this substrate feature can regulate remodeling enzymes with substantially different mechanisms. We therefore hypothesize that regulating access to the acidic patch of the nucleosome plays a key role in coordinating the activities of different remodelers in the cell. Every human cell contains nearly two meters of DNA, which is carefully packaged to form a dense structure known as chromatin. The building block of chromatin is the nucleosome, a unit composed of a short section of DNA tightly wound up around a spool-like core of proteins called histones. The tight structure of the nucleosome prevents the cell from accessing and ‘reading’ the genes in the packaged DNA, effectively switching off these genes. So the exact placement of nucleosomes helps manage which genes are turned on. Changing the position of the nucleosomes can ‘free’ the DNA and make genes available to the cell. Enzymes called chromatin remodelers move nucleosomes around – for example, they can make the histone core slide on the DNA strand. However, it is still unclear how these enzymes recognize nucleosomes. Previous research indicates that many proteins bind to nucleosomes by using a surface on the histone proteins called the acidic patch. Could chromatin remodelers also work by interacting with this acidic patch? To address this further, Gamarra et al. investigate how a chromatin remodeler enzyme known as SNF2h interacts with a nucleosome. By default, SNF2h is inactive because two of its regions called AutoN and NegC act as brakes. The experiments show that the acidic patch helps to bypass this inactivation and switches on SNF2h. Gamarra et al. propose that, when SNF2h docks on to the nucleosome, the patch provides a landing pad for the AutoN and NegC modules; this interaction activates the enzyme, which can then start remodeling the nucleosome. However, another type of chromatin remodeler also uses the patch to interact with nucleosomes but it does not have the AutoN and NegC regions. This suggests that chromatin remodelers work with the acidic patch in different ways. Overall, the findings deepen our understanding of how DNA is packaged in cells, and how this process may go wrong and cause disease.
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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
| | - Stephanie L Johnson
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Michael J Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, 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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18
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Morgan AM, LeGresley SE, Briggs K, Al-Ani G, Fischer CJ. Effects of nucleosome stability on remodeler-catalyzed repositioning. Phys Rev E 2018; 97:032422. [PMID: 29776169 DOI: 10.1103/physreve.97.032422] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Indexed: 06/08/2023]
Abstract
Chromatin remodelers are molecular motors that play essential roles in the regulation of nucleosome positioning and chromatin accessibility. These machines couple the energy obtained from the binding and hydrolysis of ATP to the mechanical work of manipulating chromatin structure through processes that are not completely understood. Here we present a quantitative analysis of nucleosome repositioning by the imitation switch (ISWI) chromatin remodeler and demonstrate that nucleosome stability significantly impacts the observed activity. We show how DNA damage induced changes in the affinity of DNA wrapping within the nucleosome can affect ISWI repositioning activity and demonstrate how assay-dependent limitations can bias studies of nucleosome repositioning. Together, these results also suggest that some of the diversity seen in chromatin remodeler activity can be attributed to the variations in the thermodynamics of interactions between the remodeler, the histones, and the DNA, rather than reflect inherent properties of the remodeler itself.
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Affiliation(s)
- Aaron M Morgan
- Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA
| | - Sarah E LeGresley
- Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA
| | - Koan Briggs
- Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA
| | - Gada Al-Ani
- Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA
| | - Christopher J Fischer
- Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA
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19
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Shukla A, Bhargava P. Regulation of tRNA gene transcription by the chromatin structure and nucleosome dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:295-309. [PMID: 29313808 DOI: 10.1016/j.bbagrm.2017.11.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/19/2023]
Abstract
The short, non-coding genes transcribed by the RNA polymerase (pol) III, necessary for survival of a cell, need to be repressed under the stress conditions in vivo. The pol III-transcribed genes have adopted several novel chromatin-based regulatory mechanisms to their advantage. In the budding yeast, the sub-nucleosomal size tRNA genes are found in the nucleosome-free regions, flanked by positioned nucleosomes at both the ends. With their chromosomes-wide distribution, all tRNA genes have a different chromatin context. A single nucleosome dynamics controls the accessibility of the genes for transcription. This dynamics operates under the influence of several chromatin modifiers in a gene-specific manner, giving the scope for differential regulation of even the isogenes within a tRNA gene family. The chromatin structure around the pol III-transcribed genes provides a context conducive for steady-state transcription as well as gene-specific transcriptional regulation upon signaling from the environmental cues. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
- Ashutosh Shukla
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India
| | - Purnima Bhargava
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India.
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20
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Perell GT, Mishra NK, Sudhamalla B, Ycas PD, Islam K, Pomerantz WCK. Specific Acetylation Patterns of H2A.Z Form Transient Interactions with the BPTF Bromodomain. Biochemistry 2017; 56:4607-4615. [PMID: 28771339 PMCID: PMC5779092 DOI: 10.1021/acs.biochem.7b00648] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Post-translational lysine acetylation of histone tails affects both chromatin accessibility and recruitment of multifunctional bromodomain-containing proteins for modulating transcription. The bromodomain- and PHD finger-containing transcription factor (BPTF) regulates transcription but has also been implicated in high gene expression levels in a variety of cancers. In this report, the histone variant H2A.Z, which replaces H2A in chromatin, is evaluated for its affinity for BPTF with a specific recognition pattern of acetylated lysine residues of the N-terminal tail region. Although BPTF immunoprecipitates H2A.Z-containing nucleosomes, a direct interaction with its bromodomain has not been reported. Using protein-observed fluorine nuclear magnetic resonance (PrOF NMR) spectroscopy, we identified a diacetylation of H2A.Z on lysine residues 4 and 11, with the highest affinity for BPTF with a Kd of 780 μM. A combination of subsequent 1H NMR Carr-Purcell-Meiboom-Gill experiments and photo-cross-linking further confirmed the specificity of the diacetylation pattern at lysines 4 and 11. Because of an adjacent PHD domain, this transient interaction may contribute to a higher-affinity bivalent interaction. Further evaluation of specificity toward a set of bromodomains, including two BET bromodomains (Brd4 and BrdT) and two Plasmodium falciparum bromodomains, resulted in one midmicromolar affinity binder, PfGCN5 (Kd = 650 μM). With these biochemical experiments, we have identified a direct interaction of histone H2A.Z with bromodomains with a specific acetylation pattern that further supports the role of H2A.Z in epigenetic regulation.
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Affiliation(s)
- Gabriella T. Perell
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Neeraj K. Mishra
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Babu Sudhamalla
- Department of Chemistry, University of Pittsburgh, 1307 Chevron Science Center, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Peter D. Ycas
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Kabirul Islam
- Department of Chemistry, University of Pittsburgh, 1307 Chevron Science Center, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - William C. K. Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
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21
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ISWI chromatin remodellers sense nucleosome modifications to determine substrate preference. Nature 2017; 548:607-611. [PMID: 28767641 DOI: 10.1038/nature23671] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 07/25/2017] [Indexed: 12/16/2022]
Abstract
ATP-dependent chromatin remodellers regulate access to genetic information by controlling nucleosome positions in vivo. However, the mechanism by which remodellers discriminate between different nucleosome substrates is poorly understood. Many chromatin remodelling proteins possess conserved protein domains that interact with nucleosomal features. Here we used a quantitative high-throughput approach, based on the use of a DNA-barcoded mononucleosome library, to profile the biochemical activity of human ISWI family remodellers in response to a diverse set of nucleosome modifications. We show that accessory (non-ATPase) subunits of ISWI remodellers can distinguish between differentially modified nucleosomes, directing remodelling activity towards specific nucleosome substrates according to their modification state. Unexpectedly, we show that the nucleosome acidic patch is necessary for maximum activity of all ISWI remodellers evaluated. This dependence also extends to CHD and SWI/SNF family remodellers, suggesting that the acidic patch may be generally required for chromatin remodelling. Critically, remodelling activity can be regulated by modifications neighbouring the acidic patch, signifying that it may act as a tunable interaction hotspot for ATP-dependent chromatin remodellers and, by extension, many other chromatin effectors that engage this region of the nucleosome surface.
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22
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Clapier CR, Kasten MM, Parnell TJ, Viswanathan R, Szerlong H, Sirinakis G, Zhang Y, Cairns BR. Regulation of DNA Translocation Efficiency within the Chromatin Remodeler RSC/Sth1 Potentiates Nucleosome Sliding and Ejection. Mol Cell 2017; 62:453-461. [PMID: 27153540 DOI: 10.1016/j.molcel.2016.03.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/29/2016] [Accepted: 03/30/2016] [Indexed: 11/30/2022]
Abstract
The RSC chromatin remodeler slides and ejects nucleosomes, utilizing a catalytic subunit (Sth1) with DNA translocation activity, which can pump DNA around the nucleosome. A central question is whether and how DNA translocation is regulated to achieve sliding versus ejection. Here, we report the regulation of DNA translocation efficiency by two domains residing on Sth1 (Post-HSA and Protrusion 1) and by actin-related proteins (ARPs) that bind Sth1. ARPs facilitated sliding and ejection by improving "coupling"-the amount of DNA translocation by Sth1 relative to ATP hydrolysis. We also identified and characterized Protrusion 1 mutations that promote "coupling," and Post-HSA mutations that improve ATP hydrolysis; notably, the strongest mutations conferred efficient nucleosome ejection without ARPs. Taken together, sliding-to-ejection involves a continuum of DNA translocation efficiency, consistent with higher magnitudes of ATPase and coupling activities (involving ARPs and Sth1 domains), enabling the simultaneous rupture of multiple histone-DNA contacts facilitating ejection.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Margaret M Kasten
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Timothy J Parnell
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ramya Viswanathan
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Heather Szerlong
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - George Sirinakis
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Bradley R Cairns
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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23
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Clapier CR, Iwasa J, Cairns BR, Peterson CL. Mechanisms of action and regulation of ATP-dependent chromatin-remodelling complexes. Nat Rev Mol Cell Biol 2017; 18:407-422. [PMID: 28512350 DOI: 10.1038/nrm.2017.26] [Citation(s) in RCA: 693] [Impact Index Per Article: 99.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells utilize diverse ATP-dependent nucleosome-remodelling complexes to carry out histone sliding, ejection or the incorporation of histone variants, suggesting that different mechanisms of action are used by the various chromatin-remodelling complex subfamilies. However, all chromatin-remodelling complex subfamilies contain an ATPase-translocase 'motor' that translocates DNA from a common location within the nucleosome. In this Review, we discuss (and illustrate with animations) an alternative, unifying mechanism of chromatin remodelling, which is based on the regulation of DNA translocation. We propose the 'hourglass' model of remodeller function, in which each remodeller subfamily utilizes diverse specialized proteins and protein domains to assist in nucleosome targeting or to differentially detect nucleosome epitopes. These modules converge to regulate a common DNA translocation mechanism, to inform the conserved ATPase 'motor' on whether and how to apply DNA translocation, which together achieve the various outcomes of chromatin remodelling: nucleosome assembly, chromatin access and nucleosome editing.
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Affiliation(s)
- Cedric R Clapier
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Bradley R Cairns
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Craig L Peterson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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24
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Wang G, Zhao J, Vasquez KM. Detection of cis- and trans-acting Factors in DNA Structure-Induced Genetic Instability Using In silico and Cellular Approaches. Front Genet 2016; 7:135. [PMID: 27532010 PMCID: PMC4969553 DOI: 10.3389/fgene.2016.00135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 07/15/2016] [Indexed: 11/13/2022] Open
Abstract
Sequences that can adopt alternative DNA structures (i.e., non-B DNA) are very abundant in mammalian genomes, and recent studies have revealed many important biological functions of non-B DNA structures in chromatin remodeling, DNA replication, transcription, and genetic instability. Here, we provide results from an in silico web-based search engine coupled with cell-based experiments to characterize the roles of non-B DNA conformations in genetic instability in eukaryotes. The purpose of this article is to illustrate strategies that can be used to identify and interrogate the biological roles of non-B DNA structures, particularly on genetic instability. We have included unpublished data using a short H-DNA-forming sequence from the human c-MYC promoter region as an example, and identified two different mechanisms of H-DNA-induced genetic instability in yeast and mammalian cells: a DNA replication-related model of mutagenesis; and a replication-independent cleavage model. Further, we identified candidate proteins involved in H-DNA-induced genetic instability by using a yeast genetic screen. A combination of in silico and cellular methods, as described here, should provide further insight into the contributions of non-B DNA structures in biological functions, genetic evolution, and disease development.
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Affiliation(s)
- Guliang Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute Austin, TX, USA
| | - Junhua Zhao
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute Austin, TX, USA
| | - Karen M Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute Austin, TX, USA
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25
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Melters DP, Nye J, Zhao H, Dalal Y. Chromatin Dynamics in Vivo: A Game of Musical Chairs. Genes (Basel) 2015; 6:751-76. [PMID: 26262644 PMCID: PMC4584328 DOI: 10.3390/genes6030751] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/17/2015] [Accepted: 07/28/2015] [Indexed: 01/30/2023] Open
Abstract
Histones are a major component of chromatin, the nucleoprotein complex fundamental to regulating transcription, facilitating cell division, and maintaining genome integrity in almost all eukaryotes. In addition to canonical, replication-dependent histones, replication-independent histone variants exist in most eukaryotes. In recent years, steady progress has been made in understanding how histone variants assemble, their involvement in development, mitosis, transcription, and genome repair. In this review, we will focus on the localization of the major histone variants H3.3, CENP-A, H2A.Z, and macroH2A, as well as how these variants have evolved, their structural differences, and their functional significance in vivo.
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Affiliation(s)
- Daniël P Melters
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
| | - Jonathan Nye
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
| | - Haiqing Zhao
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA.
| | - Yamini Dalal
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
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26
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Brysbaert G, Lensink MF, Blossey R. Regulatory motifs on ISWI chromatin remodelers: molecular mechanisms and kinetic proofreading. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:064108. [PMID: 25563573 DOI: 10.1088/0953-8984/27/6/064108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Recently, kinetic proofreading scenarios have been proposed for the regulation of chromatin remodeling, first on purely theoretical grounds (Blossey and Schiessel 2008 HFSP J. 2 167-70) and deduced from experiments on the ISWI/ACF system (Narlikar 2010 Curr. Opin. Chem. Biol. 14 660). In the kinetic proofreading scenario of chromatin remodeling, the combination of the recognition of a histone tail state and ATP-hydrolysis in the remodeler motor act together to select (i.e. proofread) a nucleosomal substrate. ISWI remodelers have recently been shown to have an additional level of regulation as they contain auto-inhibitory motifs which need to be inactivated through an interaction with the nucleosome. In this paper we show that the auto-regulatory effect enhances substrate recognition in kinetic proofreading. We further report some suggestive additional insights into the molecular mechanism underlying ISWI-autoregulation.
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Affiliation(s)
- Guillaume Brysbaert
- Interdisciplinary Research Institute, Université des Sciences et des Technologies de Lille (USTL), CNRS USR3078, 50 Avenue Halley, 59568 Villeneuve d'Ascq, France
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27
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Disruption of hSWI/SNF complexes in T cells by WAS mutations distinguishes X-linked thrombocytopenia from Wiskott-Aldrich syndrome. Blood 2014; 124:3409-19. [PMID: 25253772 DOI: 10.1182/blood-2014-07-587642] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Wiskott-Aldrich syndrome (WAS), an immunodeficiency disorder, and X-linked thrombocytopenia (XLT), a bleeding disorder, both arise from nonsynonymous mutations in WAS, which encodes a hematopoietic-specific WASp. Intriguingly, XLT evolves into WAS in some patients but not in others; yet the biological basis for this cross-phenotype (CP) effect remains unclear. Using human T-helper (TH) cells expressing different disease-causing WAS mutations, we demonstrated that hSWI/SNF-like complexes require nuclear-WASp to execute their chromatin-remodeling activity at promoters of WASp-target, immune function genes during TH1 differentiation. Hot-spot WAS mutations Thr45Met and Arg86Cys, which result in XLT-to-WAS disease progression, impair recruitment of hBRM- but not BRG1-enriched BAF complexes to IFNG and TBX21 promoters. Moreover, promoter enrichment of histone H2A.Z and its catalyzing enzyme EP400 are both impaired. Consequently, activation of Notch signaling, a hBRM-regulated event, and its downstream effector NF-κB are both compromised, along with decreased accessibility of nucleosomal DNA and inefficient transcription-elongation of WASp-target TH1 genes. In contrast, patient mutations Ala236Gly and Arg477Lys that manifest in XLT without progressing to WAS do not disrupt chromatin remodeling or transcriptional reprogramming of TH1 genes. Our study defines an indispensable relationship between nuclear-WASp- and hSWI/SNF-complexes in gene activation and reveals molecular distinctions in TH cells that might contribute to disease severity in the XLT/WAS clinical spectrum.
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28
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Karbassi E, Vondriska TM. How the proteome packages the genome for cardiovascular development. Proteomics 2014; 14:2115-26. [PMID: 25074278 DOI: 10.1002/pmic.201400131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/24/2014] [Accepted: 07/28/2014] [Indexed: 11/09/2022]
Abstract
The devastating impact of congenital heart defects has made mechanisms of vertebrate heart and vascular development an active area of study. Because myocyte death is a common feature of acquired cardiovascular diseases and the adult heart does not regenerate, the need exists to understand whether features of the developing heart and vasculature-which are more plastic-can be exploited therapeutically in the disease setting. We know that a core network of transcription factors governs commitment to the cardiovascular lineage, and recent studies using genetic loss-of-function approaches and unbiased genomic studies have revealed the role for various chromatin modulatory events. We reason that chromatin structure itself is a causal feature that influences transcriptome complexity along a developmental continuum, and the purpose of this article is to highlight the areas in which 'omics technologies have the potential to reveal new principles of phenotypic plasticity in development. We review the major mechanisms of chromatin structural regulation, highlighting what is known about their actions to control cardiovascular differentiation. We discuss emergent mechanisms of regulation that have been identified on the basis of genomic and proteomic studies of cardiac nuclei and identify current challenges to an integrated understanding of chromatin structure and cardiovascular phenotype.
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Affiliation(s)
- Elaheh Karbassi
- Departments of Anesthesiology, Medicine and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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29
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Talbert PB, Henikoff S. Environmental responses mediated by histone variants. Trends Cell Biol 2014; 24:642-50. [PMID: 25150594 DOI: 10.1016/j.tcb.2014.07.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 01/19/2023]
Abstract
Fluctuations in the ambient environment can trigger chromatin disruptions, involving replacement of nucleosomes or exchange of their histone subunits. Unlike canonical histones, which are available only during S-phase, replication-independent histone variants are present throughout the cell cycle and are adapted for chromatin repair. The H2A.Z variant mediates responses to environmental perturbations including fluctuations in temperature and seasonal variation. Phosphorylation of histone H2A.X rapidly marks double-strand DNA breaks for chromatin repair, which is mediated by both H2A and H3 histone variants. Other histones are used as weapons in conflicts between parasites and their hosts, which suggests broad involvement of histone variants in environmental responses beyond chromatin repair.
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Affiliation(s)
- Paul B Talbert
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Seattle, WA 98109, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Seattle, WA 98109, USA.
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30
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Abstract
Eukaryotic gene regulation involves a balance between packaging of the genome into nucleosomes and enabling access to regulatory proteins and RNA polymerase. Nucleosomes, consisting of DNA wrapped around a core of histone proteins, are integral components of gene regulation that restrict access to both regulatory sequences and the underlying template. In this review, Weber and Henikoff consider how histone variants and their interacting partners are involved in transcriptional regulation through the creation of unique chromatin states. Eukaryotic gene regulation involves a balance between packaging of the genome into nucleosomes and enabling access to regulatory proteins and RNA polymerase. Nucleosomes are integral components of gene regulation that restrict access to both regulatory sequences and the underlying template. Whereas canonical histones package the newly replicated genome, they can be replaced with histone variants that alter nucleosome structure, stability, dynamics, and, ultimately, DNA accessibility. Here we consider how histone variants and their interacting partners are involved in transcriptional regulation through the creation of unique chromatin states.
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Affiliation(s)
- Christopher M Weber
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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31
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Weber CM, Ramachandran S, Henikoff S. Nucleosomes are context-specific, H2A.Z-modulated barriers to RNA polymerase. Mol Cell 2014; 53:819-30. [PMID: 24606920 DOI: 10.1016/j.molcel.2014.02.014] [Citation(s) in RCA: 263] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/04/2013] [Accepted: 01/28/2014] [Indexed: 01/03/2023]
Abstract
Nucleosomes are barriers to transcription in vitro; however, their effects on RNA polymerase in vivo are unknown. Here we describe a simple and general strategy to comprehensively map the positions of elongating and arrested RNA polymerase II (RNAPII) at nucleotide resolution. We find that the entry site of the first (+1) nucleosome is a barrier to RNAPII for essentially all genes, including those undergoing regulated pausing farther upstream. In contrast to the +1 nucleosome, gene body nucleosomes are low barriers and cause RNAPII stalling both at the entry site and near the dyad axis. The extent of the +1 nucleosome barrier correlates with nucleosome occupancy but anticorrelates with enrichment of histone variant H2A.Z. Importantly, depletion of H2A.Z from a nucleosome position results in a higher barrier to RNAPII. Our results suggest that nucleosomes present significant, context-specific barriers to RNAPII in vivo that can be tuned by the incorporation of H2A.Z.
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Affiliation(s)
- Christopher M Weber
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Srinivas Ramachandran
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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32
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Regulation of ISWI chromatin remodelling activity. Chromosoma 2014; 123:91-102. [PMID: 24414837 DOI: 10.1007/s00412-013-0447-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/20/2013] [Accepted: 11/25/2013] [Indexed: 12/22/2022]
Abstract
The packaging of the eukaryotic genome into chromatin facilitates the storage of the genetic information within the nucleus, but prevents the access to the underlying DNA sequences. Structural changes in chromatin are mediated by several mechanisms. Among them, ATP-dependent remodelling complexes belonging to ISWI family provides one of the best examples that eukaryotic cells evolved to finely regulate these changes. ISWI-containing complexes use the energy derived from ATP hydrolysis to rearrange nucleosomes on chromatin in order to favour specific nuclear reactions. The combination of regulatory nuclear factors associated with the ATPase subunit as well as its modulation by specific histone modifications, specializes the nuclear function of each ISWI-containing complex. Here we review the different ways by which ISWI enzymatic activity can be modulated and regulated in the nucleus of eukaryotic cells.
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33
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Hu Y, Zhu N, Wang X, Yi Q, Zhu D, Lai Y, Zhao Y. Analysis of rice Snf2 family proteins and their potential roles in epigenetic regulation. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 70:33-42. [PMID: 23770592 DOI: 10.1016/j.plaphy.2013.05.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/02/2013] [Indexed: 05/24/2023]
Abstract
Snf2 family proteins are ATP-dependent chromatin remodeling factors that control many aspects of DNA events such as transcription, replication, homologous recombination and DNA repair. In animals several members in this family have been revealed to control gene expression in concert with other epigenetic mechanisms including histone modification, histone variants and DNA methylation. Their function in regulating genome expression in plant has hardly been disclosed before except in Arabidopsis. Here we identified 40 members of this family in the rice (Oryza Sativa) genome and constructed a phylogenetic tree together with Arabidopsis 41 Snf2 proteins. Sequence alignment of the Snf2 helicase regions revealed conserved motifs and blocks in most proteins. Expression profile analysis indicates that many rice Snf2 family genes show a tissue-specific expression pattern and some of them respond to abiotic stresses including drought, salt and cold. The results provide a basis for further analysis of their roles in epigenetic regulation to control rice development.
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Affiliation(s)
- Yongfeng Hu
- Jingchu University of Technology, 448000 Jingmen, China.
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34
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The variant histone H2A.V of Drosophila--three roles, two guises. Chromosoma 2013; 122:245-58. [PMID: 23553272 DOI: 10.1007/s00412-013-0409-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/19/2013] [Accepted: 03/21/2013] [Indexed: 12/15/2022]
Abstract
Histone variants play important roles in eukaryotic genome organization, the control of gene expression, cell division and DNA repair. Unlike other organisms that employ several H2A variants for different functions, the parsimonious fruit fly Drosophila melanogaster gets along with just a single H2A variant, H2A.V. Remarkably, H2A.V unites within one molecule features and functions of two different mammalian H2A variants, H2A.Z and H2A.X. Accordingly, H2A.V is involved in diverse functions, as an element of a class of active promoter structure, as a foundation for heterochromatin assembly and as a DNA damage sensor. Here, we comprehensively review the current knowledge of this fascinating histone variant.
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35
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Deng X, Berletch JB, Ma W, Nguyen DK, Hiatt JB, Noble WS, Shendure J, Disteche CM. Mammalian X upregulation is associated with enhanced transcription initiation, RNA half-life, and MOF-mediated H4K16 acetylation. Dev Cell 2013; 25:55-68. [PMID: 23523075 DOI: 10.1016/j.devcel.2013.01.028] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 01/07/2013] [Accepted: 01/13/2013] [Indexed: 12/13/2022]
Abstract
X upregulation in mammals increases levels of expressed X-linked transcripts to compensate for autosomal biallelic expression. Here, we present molecular mechanisms that enhance X expression at transcriptional and posttranscriptional levels. Active mouse X-linked promoters are enriched in the initiation form of RNA polymerase II (PolII-S5p) and in specific histone marks, including histone H4 acetylated at lysine 16 (H4K16ac) and histone variant H2AZ. The H4K16 acetyltransferase males absent on the first (MOF), known to mediate the Drosophila X upregulation, is also enriched on the mammalian X. Depletion of MOF or male-specific lethal 1 (MSL1) in mouse ES cells causes a specific decrease in PolII-S5p and in expression of a subset of X-linked genes. Analyses of RNA half-life data sets show increased stability of mammalian X-linked transcripts. Both ancestral X-linked genes, defined as those conserved on chicken autosomes, and newly acquired X-linked genes are upregulated by similar mechanisms but to a different extent, suggesting that subsets of genes are distinctly regulated depending on their evolutionary history.
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Affiliation(s)
- Xinxian Deng
- Department of Pathology, School of Medicine, University of Washington, Seattle, WA 98195, USA
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36
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Hu G, Cui K, Northrup D, Liu C, Wang C, Tang Q, Ge K, Levens D, Crane-Robinson C, Zhao K. H2A.Z facilitates access of active and repressive complexes to chromatin in embryonic stem cell self-renewal and differentiation. Cell Stem Cell 2013; 12:180-92. [PMID: 23260488 PMCID: PMC3570599 DOI: 10.1016/j.stem.2012.11.003] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 09/29/2012] [Accepted: 11/08/2012] [Indexed: 10/27/2022]
Abstract
Chromatin modifications have been implicated in the self-renewal and differentiation of embryonic stem cells (ESCs). However, the function of histone variant H2A.Z in ESCs remains unclear. We show that H2A.Z is highly enriched at promoters and enhancers and is required for both efficient self-renewal and differentiation of murine ESCs. H2A.Z deposition leads to an abnormal nucleosome structure, decreased nucleosome occupancy, and increased chromatin accessibility. In self-renewing ESCs, knockdown of H2A.Z compromises OCT4 binding to its target genes and leads to decreased binding of MLL complexes to active genes and of PRC2 complex to repressed genes. During differentiation of ESCs, inhibition of H2A.Z also compromises RA-induced RARα binding, activation of differentiation markers, and the repression of pluripotency genes. We propose that H2A.Z mediates such contrasting activities by acting as a general facilitator that generates access for a variety of complexes, both activating and repressive.
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Affiliation(s)
- Gangqing Hu
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Kairong Cui
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Daniel Northrup
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Chengyu Liu
- Transgenic Mouse Facility, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chaochen Wang
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Qingsong Tang
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Kai Ge
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Levens
- Laboratory of Pathology, National Cancer Institute, Bethesda, MD 20892, USA
| | - Colyn Crane-Robinson
- Biophysics Laboratories, St. Michael’s Building, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Keji Zhao
- Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
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37
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Abstract
In the eukaryotic nucleus, processes of DNA metabolism such as transcription, DNA replication, and repair occur in the context of DNA packaged into nucleosomes and higher order chromatin structures. In order to overcome the barrier presented by chromatin structures to the protein machinery carrying out these processes, the cell relies on a class of enzymes called chromatin remodeling complexes which catalyze ATP-dependent restructuring and repositioning of nucleosomes. Chromatin remodelers are large multi-subunit complexes which all share a common SF2 helicase ATPase domain in their catalytic subunit, and are classified into four different families-SWI/SNF, ISWI, CHD, INO80-based on the arrangement of other domains in their catalytic subunit as well as their non-catalytic subunit composition. A large body of structural, biochemical, and biophysical evidence suggests chromatin remodelers operate as histone octamer-anchored directional DNA translocases in order to disrupt DNA-histone interactions and catalyze nucleosome sliding. Remodeling mechanisms are family-specific and depend on factors such as how the enzyme engages with nucleosomal and linker DNA, features of DNA loop intermediates, specificity for mono- or oligonucleosomal substrates, and ability to remove histones and exchange histone variants. Ultimately, the biological function of chromatin remodelers and their genomic targeting in vivo is regulated by each complex's subunit composition, association with chromatin modifiers and histone chaperones, and affinity for chromatin signals such as histone posttranslational modifications.
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38
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Bönisch C, Hake SB. Histone H2A variants in nucleosomes and chromatin: more or less stable? Nucleic Acids Res 2012; 40:10719-41. [PMID: 23002134 PMCID: PMC3510494 DOI: 10.1093/nar/gks865] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In eukaryotes, DNA is organized together with histones and non-histone proteins into a highly complex nucleoprotein structure called chromatin, with the nucleosome as its monomeric subunit. Various interconnected mechanisms regulate DNA accessibility, including replacement of canonical histones with specialized histone variants. Histone variant incorporation can lead to profound chromatin structure alterations thereby influencing a multitude of biological processes ranging from transcriptional regulation to genome stability. Among core histones, the H2A family exhibits highest sequence divergence, resulting in the largest number of variants known. Strikingly, H2A variants differ mostly in their C-terminus, including the docking domain, strategically placed at the DNA entry/exit site and implicated in interactions with the (H3–H4)2-tetramer within the nucleosome and in the L1 loop, the interaction interface of H2A–H2B dimers. Moreover, the acidic patch, important for internucleosomal contacts and higher-order chromatin structure, is altered between different H2A variants. Consequently, H2A variant incorporation has the potential to strongly regulate DNA organization on several levels resulting in meaningful biological output. Here, we review experimental evidence pinpointing towards outstanding roles of these highly variable regions of H2A family members, docking domain, L1 loop and acidic patch, and close by discussing their influence on nucleosome and higher-order chromatin structure and stability.
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Affiliation(s)
- Clemens Bönisch
- Department of Molecular Biology, Center for Integrated Protein Science Munich, Adolf-Butenandt-Institute, Ludwig-Maximilians-University Munich, 80336 Munich, Germany.
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39
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Histone variant H2A.Bbd is associated with active transcription and mRNA processing in human cells. Mol Cell 2012; 47:596-607. [PMID: 22795134 DOI: 10.1016/j.molcel.2012.06.011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 02/20/2012] [Accepted: 06/07/2012] [Indexed: 12/22/2022]
Abstract
Variation in chromatin composition and organization often reflects differences in genome function. Histone variants, for example, replace canonical histones to contribute to regulation of numerous nuclear processes including transcription, DNA repair, and chromosome segregation. Here we focus on H2A.Bbd, a rapidly evolving variant found in mammals but not in invertebrates. We report that in human cells, nucleosomes bearing H2A.Bbd form unconventional chromatin structures enriched within actively transcribed genes and characterized by shorter DNA protection and nucleosome spacing. Analysis of transcriptional profiles from cells depleted for H2A.Bbd demonstrated widespread changes in gene expression with a net downregulation of transcription and disruption of normal mRNA splicing patterns. In particular, we observed changes in exon inclusion rates and increased presence of intronic sequences in mRNA products upon H2A.Bbd depletion. Taken together, our results indicate that H2A.Bbd is involved in formation of a specific chromatin structure that facilitates both transcription and initial mRNA processing.
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40
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New insights into nucleosome and chromatin structure: an ordered state or a disordered affair? Nat Rev Mol Cell Biol 2012; 13:436-47. [PMID: 22722606 DOI: 10.1038/nrm3382] [Citation(s) in RCA: 473] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The compaction of genomic DNA into chromatin has profound implications for the regulation of key processes such as transcription, replication and DNA repair. Nucleosomes, the repeating building blocks of chromatin, vary in the composition of their histone protein components. This is the result of the incorporation of variant histones and post-translational modifications of histone amino acid side chains. The resulting changes in nucleosome structure, stability and dynamics affect the compaction of nucleosomal arrays into higher-order structures. It is becoming clear that chromatin structures are not nearly as uniform and regular as previously assumed. This implies that chromatin structure must also be viewed in the context of specific biological functions.
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41
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Alkhatib SG, Landry JW. The nucleosome remodeling factor. FEBS Lett 2011; 585:3197-207. [PMID: 21920360 PMCID: PMC4839296 DOI: 10.1016/j.febslet.2011.09.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 09/02/2011] [Accepted: 09/02/2011] [Indexed: 12/19/2022]
Abstract
An essential component of the chromatin remodeling machinery is NURF (Nucleosome Remodeling Factor), the founding member of the ISWI family of chromatin remodeling complexes. In vertebrates and invertebrates alike, NURF has many important functions in chromatin biology including regulating transcription, establishing boundary elements, and promoting higher order chromatin structure. Since NURF is essential to many aspects of chromatin biology, knowledge of its function is required to fully understand how the genome is regulated. This review will summarize what is currently known of its biological functions, conservation in the most prominent model organisms, biochemical functions as a nucleosome remodeling enzyme, and its possible relevance to human cancer.
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Affiliation(s)
- Suehyb G. Alkhatib
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, United States
| | - Joseph W. Landry
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, United States
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42
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Erdel F, Rippe K. Chromatin remodelling in mammalian cells by ISWI-type complexes--where, when and why? FEBS J 2011; 278:3608-18. [PMID: 21810179 DOI: 10.1111/j.1742-4658.2011.08282.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The specific location of nucleosomes on DNA has important inhibitory or activating roles in the regulation of DNA-dependent processes as it affects the DNA accessibility. Nucleosome positions depend on the ATP-coupled activity of chromatin-remodelling complexes that translocate nucleosomes or evict them from the DNA. The mammalian cell harbors numerous different remodelling complexes that possess distinct activities. These can translate a variety of signals into certain patterns of nucleosome positions with specific functions. Although chromatin remodellers have been extensively studied in vitro, much less is known about how they operate in their cellular environment. Here, we review the cellular activities of the mammalian imitation switch proteins and discuss mechanisms by which they are targeted to sites where their activity is needed.
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Affiliation(s)
- Fabian Erdel
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, Heidelberg, Germany
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43
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Erdel F, Krug J, Längst G, Rippe K. Targeting chromatin remodelers: signals and search mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:497-508. [PMID: 21704204 DOI: 10.1016/j.bbagrm.2011.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 06/02/2011] [Accepted: 06/06/2011] [Indexed: 12/26/2022]
Abstract
Chromatin remodeling complexes are ATP-driven molecular machines that change chromatin structure by translocating nucleosomes along the DNA, evicting nucleosomes, or changing the nucleosomal histone composition. They are highly abundant in the cell and numerous different complexes exist that display distinct activity patterns. Here we review chromatin-associated signals that are recognized by remodelers. It is discussed how these regulate the remodeling reaction via changing the nucleosome substrate/product binding affinity or the catalytic translocation rate. Finally, we address the question of how chromatin remodelers operate in the cell nucleus to find specifically marked nucleosome substrates via a diffusion driven target location mechanism, and estimate the search times of this process. This article is part of a Special Issue entitled:Snf2/Swi2 ATPase structure and function.
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Affiliation(s)
- Fabian Erdel
- Research Group Genome Organization & Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Loss of H2A.Z Is Not Sufficient to Determine Transcriptional Activity of Snf2-Related CBP Activator Protein or p400 Complexes. Int J Cell Biol 2011; 2011:715642. [PMID: 21785598 PMCID: PMC3140016 DOI: 10.1155/2011/715642] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 04/01/2011] [Indexed: 12/04/2022] Open
Abstract
The p400 and SRCAP (Snf2-related CBP activator protein) complexes remodel chromatin by catalyzing deposition of histone H2A.Z into nucleosomes. This remodeling activity has been proposed as a basis for regulation of transcription by these complexes. Transcript levels of p21 or Sp1 mRNAs after knockdown of p400 or SRCAP reveals that each regulates transcription of these promoters differently. In this study, we asked whether deposition of H2A.Z within specific nucleosomes by p400 or SRCAP dictates transcriptional activity. Our data indicates that nucleosome density at specific p21 or Sp1 promoter positions is not altered by the loss of either remodeling complex. However, knockdown of SRCAP or p400 reduces deposition of H2A.Z∼50% into all p21 and Sp1 promoter nucleosomes. Thus, H2A.Z deposition is not targeted to specific nucleosomes. These results indicate that the deposition of H2A.Z by the p400 or SRCAP complexes is not sufficient to determine how each regulates transcription. This conclusion is further supported by studies that demonstrate a SRCAPΔATP
mutant unable to deposit H2A.Z has similar transcriptional activity as wild-type SRCAP.
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TbISWI regulates multiple polymerase I (Pol I)-transcribed loci and is present at Pol II transcription boundaries in Trypanosoma brucei. EUKARYOTIC CELL 2011; 10:964-76. [PMID: 21571922 DOI: 10.1128/ec.05048-11] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The unicellular eukaryote Trypanosoma brucei is unusual in having very little transcriptional control. The bulk of the T. brucei genome is constitutively transcribed by RNA polymerase II (Pol II) as extensive polycistronic transcription units. Exceptions to this rule include several RNA Pol I transcription units such as the VSG expression sites (ESs), which are mono-allelically expressed. TbISWI, a member of the SWI2/SNF2 related chromatin remodeling ATPases, plays a role in repression of Pol I-transcribed ESs in both bloodstream- and procyclic-form T. brucei. We show that TbISWI binds both active and silent ESs but is depleted from the ES promoters themselves. TbISWI knockdown results in an increase in VSG transcripts from the silent VSG ESs. In addition to its role in the repression of the silent ESs, TbISWI also contributes to the downregulation of the Pol I-transcribed procyclin loci, as well as nontranscribed VSG basic copy arrays and minichromosomes. We also show that TbISWI is enriched at a number of strand switch regions which form the boundaries between Pol II transcription units. These strand switch regions are the presumed sites of Pol II transcription initiation and termination and are enriched in modified histones and histone variants. Our results indicate that TbISWI is a versatile chromatin remodeler that regulates transcription at multiple Pol I loci and is particularly abundant at many Pol II transcription boundaries in T. brucei.
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Sirinakis G, Clapier CR, Gao Y, Viswanathan R, Cairns BR, Zhang Y. The RSC chromatin remodelling ATPase translocates DNA with high force and small step size. EMBO J 2011; 30:2364-72. [PMID: 21552204 DOI: 10.1038/emboj.2011.141] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 04/04/2011] [Indexed: 11/09/2022] Open
Abstract
ATP-dependent chromatin remodelling complexes use the energy of ATP hydrolysis to reposition and reconfigure nucleosomes. Despite their diverse functions, all remodellers share highly conserved ATPase domains, many shown to translocate DNA. Understanding remodelling requires biophysical knowledge of the DNA translocation process: how the ATPase moves DNA and generates force, and how translocation and force generation are coupled on nucleosomes. Here, we characterize the real-time activity of a minimal RSC translocase 'motor' on bare DNA, using high-resolution optical tweezers and a 'tethered' translocase system. We observe on dsDNA a processivity of ∼35 bp, a speed of ∼25 bp/s, and a step size of 2.0 (±0.4, s.e.m.) bp. Surprisingly, the motor is capable of moving against high force, up to 30 pN, making it one of the most force-resistant motors known. We also provide evidence for DNA 'buckling' at initiation. These observations reveal the ATPase as a powerful DNA translocating motor capable of disrupting DNA-histone interactions by mechanical force.
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Affiliation(s)
- George Sirinakis
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, USA
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H2A.Z nucleosomes enriched over active genes are homotypic. Nat Struct Mol Biol 2010; 17:1500-7. [PMID: 21057526 PMCID: PMC3051840 DOI: 10.1038/nsmb.1926] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 09/09/2010] [Indexed: 02/07/2023]
Abstract
Nucleosomes that contain the histone variant H2A.Z are enriched around transcriptional start sites, but the mechanistic basis for this enrichment is unknown. A single octameric nucleosome can contain two H2A.Z histones (homotypic) or one H2A.Z and one canonical H2A (heterotypic). To elucidate the function of H2A.Z, we generated high-resolution maps of homotypic and heterotypic Drosophila H2A.Z (H2Av) nucleosomes. Although homotypic and heterotypic H2A.Z nucleosomes mapped throughout most of the genome, homotypic nucleosomes were enriched and heterotypic nucleosomes were depleted downstream of active promoters and intron-exon junctions. The distribution of homotypic H2A.Z nucleosomes resembled that of classical active chromatin and showed evidence of disruption during transcriptional elongation. Both homotypic H2A.Z nucleosomes and classical active chromatin were depleted downstream of paused polymerases. Our results suggest that H2A.Z enrichment patterns result from intrinsic structural differences between heterotypic and homotypic H2A.Z nucleosomes that follow disruption during transcriptional elongation.
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Cruickshank MN, Besant P, Ulgiati D. The impact of histone post-translational modifications on developmental gene regulation. Amino Acids 2010; 39:1087-105. [PMID: 20204433 DOI: 10.1007/s00726-010-0530-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 02/12/2010] [Indexed: 02/06/2023]
Abstract
Eukaryotic genomic DNA is orderly compacted to fit into the nucleus and to inhibit accessibility of specific sequences. DNA is manipulated in many different ways by bound RNA and proteins within the composite material known as chromatin. All of the biological processes that require access to genomic DNA (such as replication, recombination and transcription) therefore are dependent on the precise characteristics of chromatin in eukaryotes. This distinction underlies a fundamental property of eukaryotic versus prokaryotic gene regulation such that chromatin structure must be regulated to precisely repress or relieve repression of particular regions of the genome in an appropriate spatio-temporal manner. As well as playing a key role in structuring genomic DNA, histones are subject to site-specific modifications that can influence the organization of chromatin structure. This review examines the molecular processes regulating site-specific histone acetylation, methylation and phosphorylation with an emphasis on how these processes underpin differentiation-regulated transcription.
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Affiliation(s)
- Mark N Cruickshank
- Biochemistry and Molecular Biology, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
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Abstract
Histones wrap DNA to form nucleosome particles that compact eukaryotic genomes. Variant histones have evolved crucial roles in chromosome segregation, transcriptional regulation, DNA repair, sperm packaging and other processes. 'Universal' histone variants emerged early in eukaryotic evolution and were later displaced for bulk packaging roles by the canonical histones (H2A, H2B, H3 and H4), the synthesis of which is coupled to DNA replication. Further specializations of histone variants have evolved in some lineages to perform additional tasks. Differences among histone variants in their stability, DNA wrapping, specialized domains that regulate access to DNA, and post-translational modifications, underlie the diverse functions that histones have acquired in evolution.
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Abstract
As environmental temperatures rise, plants seek help from their core molecular mechanisms to adapt. One molecule that comes to the rescue, regulating gene expression, is the chromatin protein H2A.Z.
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