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Aljahani A, Mauksch C, Oudelaar AM. The relationship between nucleosome positioning and higher-order genome folding. Curr Opin Cell Biol 2024; 89:102398. [PMID: 38991477 DOI: 10.1016/j.ceb.2024.102398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/23/2024] [Accepted: 06/18/2024] [Indexed: 07/13/2024]
Abstract
Eukaryotic genomes are organized into 3D structures, which range from small-scale nucleosome arrays to large-scale chromatin domains. These structures have an important role in the regulation of transcription and other nuclear processes. Despite advances in our understanding of the properties, functions, and underlying mechanisms of genome structures, there are many open questions about the interplay between these structures across scales. In particular, it is not well understood if and how 1D features of nucleosome arrays influence large-scale 3D genome folding patterns. In this review, we discuss recent studies that address these questions and summarize our current understanding of the relationship between nucleosome positioning and higher-order genome folding.
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Affiliation(s)
- Abrar Aljahani
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany; University of Göttingen, Göttingen, Germany
| | - Clemens Mauksch
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany; University of Göttingen, Göttingen, Germany
| | - A Marieke Oudelaar
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany.
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Wakim JG, Spakowitz AJ. Physical modeling of nucleosome clustering in euchromatin resulting from interactions between epigenetic reader proteins. Proc Natl Acad Sci U S A 2024; 121:e2317911121. [PMID: 38900792 PMCID: PMC11214050 DOI: 10.1073/pnas.2317911121] [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: 10/14/2023] [Accepted: 04/15/2024] [Indexed: 06/22/2024] Open
Abstract
Euchromatin is an accessible phase of genetic material containing genes that encode proteins with increased expression levels. The structure of euchromatin in vitro has been described as a 30-nm fiber formed from ordered nucleosome arrays. However, recent advances in microscopy have revealed an in vivo euchromatin architecture that is much more disordered, characterized by variable-length linker DNA and sporadic nucleosome clusters. In this work, we develop a theoretical model to elucidate factors contributing to the disordered in vivo architecture of euchromatin. We begin by developing a 1D model of nucleosome positioning that captures the interactions between bound epigenetic reader proteins to predict the distribution of DNA linker lengths between adjacent nucleosomes. We then use the predicted linker lengths to construct 3D chromatin configurations consistent with the physical properties of DNA within the nucleosome array, and we evaluate the distribution of nucleosome cluster sizes in those configurations. Our model reproduces experimental cluster-size distributions, which are dramatically influenced by the local pattern of epigenetic marks and the concentration of reader proteins. Based on our model, we attribute the disordered arrangement of euchromatin to the heterogeneous binding of reader proteins and subsequent short-range interactions between bound reader proteins on adjacent nucleosomes. By replicating experimental results with our physics-based model, we propose a mechanism for euchromatin organization in the nucleus that impacts gene regulation and the maintenance of epigenetic marks.
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Affiliation(s)
- Joseph G. Wakim
- Department of Chemical Engineering, Stanford University, Stanford, CA94305
| | - Andrew J. Spakowitz
- Department of Chemical Engineering, Stanford University, Stanford, CA94305
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305
- Biophysics Program, Stanford University, Stanford, CA94305
- Department of Applied Physics, Stanford University, Stanford, CA94305
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3
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Serra-Cardona A, Hua X, McNutt SW, Zhou H, Toda T, Jia S, Chu F, Zhang Z. The PCNA-Pol δ complex couples lagging strand DNA synthesis to parental histone transfer for epigenetic inheritance. SCIENCE ADVANCES 2024; 10:eadn5175. [PMID: 38838138 PMCID: PMC11152121 DOI: 10.1126/sciadv.adn5175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 05/01/2024] [Indexed: 06/07/2024]
Abstract
Inheritance of epigenetic information is critical for maintaining cell identity. The transfer of parental histone H3-H4 tetramers, the primary carrier of epigenetic modifications on histone proteins, represents a crucial yet poorly understood step in the inheritance of epigenetic information. Here, we show the lagging strand DNA polymerase, Pol δ, interacts directly with H3-H4 and that the interaction between Pol δ and the sliding clamp PCNA regulates parental histone transfer to lagging strands, most likely independent of their roles in DNA synthesis. When combined, mutations at Pol δ and Mcm2 that compromise parental histone transfer result in a greater reduction in nucleosome occupancy at nascent chromatin than mutations in either alone. Last, PCNA contributes to nucleosome positioning on nascent chromatin. On the basis of these results, we suggest that the PCNA-Pol δ complex couples lagging strand DNA synthesis to parental H3-H4 transfer, facilitating epigenetic inheritance.
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Affiliation(s)
- Albert Serra-Cardona
- Institute for Cancer Genetics, Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10019, USA
| | - Xu Hua
- Institute for Cancer Genetics, Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10019, USA
| | - Seth W. McNutt
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Hui Zhou
- Institute for Cancer Genetics, Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10019, USA
| | - Takenori Toda
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Feixia Chu
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Zhiguo Zhang
- Institute for Cancer Genetics, Department of Pediatrics and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10019, USA
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Karri S, Yang Y, Zhou J, Dickinson Q, Jia J, Huang Y, Wang Z, Gan H, Yu C. Defective transfer of parental histone decreases frequency of homologous recombination by increasing free histone pools in budding yeast. Nucleic Acids Res 2024; 52:5138-5151. [PMID: 38554108 PMCID: PMC11109958 DOI: 10.1093/nar/gkae205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/27/2024] [Accepted: 03/08/2024] [Indexed: 04/01/2024] Open
Abstract
Recycling of parental histones is an important step in epigenetic inheritance. During DNA replication, DNA polymerase epsilon subunit DPB3/DPB4 and DNA replication helicase subunit MCM2 are involved in the transfer of parental histones to the leading and lagging strands, respectively. Single Dpb3 deletion (dpb3Δ) or Mcm2 mutation (mcm2-3A), which each disrupts one parental histone transfer pathway, leads to the other's predominance. However, the biological impact of the two histone transfer pathways on chromatin structure and DNA repair remains elusive. In this study, we used budding yeast Saccharomyces cerevisiae to determine the genetic and epigenetic outcomes from disruption of parental histone H3-H4 tetramer transfer. We found that a dpb3Δ mcm2-3A double mutant did not exhibit the asymmetric parental histone patterns caused by a single dpb3Δ or mcm2-3A mutation, suggesting that the processes by which parental histones are transferred to the leading and lagging strands are independent. Surprisingly, the frequency of homologous recombination was significantly lower in dpb3Δ, mcm2-3A and dpb3Δ mcm2-3A mutants, likely due to the elevated levels of free histones detected in the mutant cells. Together, these findings indicate that proper transfer of parental histones during DNA replication is essential for maintaining chromatin structure and that lower homologous recombination activity due to parental histone transfer defects is detrimental to cells.
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Affiliation(s)
- Srinivasu Karri
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Yi Yang
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Jiaqi Zhou
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Quinn Dickinson
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Jing Jia
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Yuxin Huang
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Zhiquan Wang
- Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Haiyun Gan
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Chuanhe Yu
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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Dennis AF, Xu Z, Clark DJ. Examining chromatin heterogeneity through PacBio long-read sequencing of M.EcoGII methylated genomes: an m6A detection efficiency and calling bias correcting pipeline. Nucleic Acids Res 2024; 52:e45. [PMID: 38634798 PMCID: PMC11109960 DOI: 10.1093/nar/gkae288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/23/2024] [Accepted: 04/04/2024] [Indexed: 04/19/2024] Open
Abstract
Recent studies have combined DNA methyltransferase footprinting of genomic DNA in nuclei with long-read sequencing, resulting in detailed chromatin maps for multi-kilobase stretches of genomic DNA from one cell. Theoretically, nucleosome footprints and nucleosome-depleted regions can be identified using M.EcoGII, which methylates adenines in any sequence context, providing a high-resolution map of accessible regions in each DNA molecule. Here, we report PacBio long-read sequence data for budding yeast nuclei treated with M.EcoGII and a bioinformatic pipeline which corrects for three key challenges undermining this promising method. First, detection of m6A in individual DNA molecules by the PacBio software is inefficient, resulting in false footprints predicted by random gaps of seemingly unmethylated adenines. Second, there is a strong bias against m6A base calling as AT content increases. Third, occasional methylation occurs within nucleosomes, breaking up their footprints. After correcting for these issues, our pipeline calculates a correlation coefficient-based score indicating the extent of chromatin heterogeneity within the cell population for every gene. Although the population average is consistent with that derived using other techniques, we observe a wide range of heterogeneity in nucleosome positions at the single-molecule level, probably reflecting cellular chromatin dynamics.
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Affiliation(s)
- Allison F Dennis
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhuwei Xu
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - David J Clark
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Tian C, Zhang Q, Jia J, Zhou J, Zhang Z, Karri S, Jiang J, Dickinson Q, Yao Y, Tang X, Huang Y, Guo T, He Z, Liu Z, Gao Y, Yang X, Wu Y, Chan KM, Zhang D, Han J, Yu C, Gan H. DNA polymerase delta governs parental histone transfer to DNA replication lagging strand. Proc Natl Acad Sci U S A 2024; 121:e2400610121. [PMID: 38713623 PMCID: PMC11098083 DOI: 10.1073/pnas.2400610121] [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: 01/17/2024] [Accepted: 04/01/2024] [Indexed: 05/09/2024] Open
Abstract
Chromatin replication is intricately intertwined with the recycling of parental histones to the newly duplicated DNA strands for faithful genetic and epigenetic inheritance. The transfer of parental histones occurs through two distinct pathways: leading strand deposition, mediated by the DNA polymerase ε subunits Dpb3/Dpb4, and lagging strand deposition, facilitated by the MCM helicase subunit Mcm2. However, the mechanism of the facilitation of Mcm2 transferring parental histones to the lagging strand while moving along the leading strand remains unclear. Here, we show that the deletion of Pol32, a nonessential subunit of major lagging-strand DNA polymerase δ, results in a predominant transfer of parental histone H3-H4 to the leading strand during replication. Biochemical analyses further demonstrate that Pol32 can bind histone H3-H4 both in vivo and in vitro. The interaction of Pol32 with parental histone H3-H4 is disrupted through the mutation of the histone H3-H4 binding domain within Mcm2. Our findings identify the DNA polymerase δ subunit Pol32 as a critical histone chaperone downstream of Mcm2, mediating the transfer of parental histones to the lagging strand during DNA replication.
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Affiliation(s)
- Congcong Tian
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
| | - Qin Zhang
- Department of Biotherapy, Cancer Center and State Laboratory of Biotherapy, and Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, Sichuan Province610041, China
| | - Jing Jia
- Hormel Institute, University of Minnesota, Austin, MN55912
| | - Jiaqi Zhou
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
| | - Ziwei Zhang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
| | | | - Jiuhang Jiang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong510642, China
| | | | - Yuan Yao
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
| | - Xiaorong Tang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
- Cancer Centre, Faculty of Health Sciences, University of Macau, Macau, China
| | - Yuxin Huang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong510642, China
| | - Ting Guo
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
- School of Life Sciences, Henan University, Kaifeng475004, China
- Shenzhen Research Institute of Henan University, Shenzhen518000, China
| | - Ziwei He
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, Chinese University of Hong Kong, Shenzhen518172, China
| | - Zheng Liu
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, Chinese University of Hong Kong, Shenzhen518172, China
| | - Yuan Gao
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Xinran Yang
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
| | - Yuchun Wu
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
- Pathology and Pathophysiology Basic Medical School, Qingdao University, Qindao266000, China
| | - Kui Ming Chan
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong Special Administration Region, China
- Key Laboratory of Biochip Technology, Biotech and Health Centre, Shenzhen Research Institute of City University of Hong Kong, Shenzhen518172, China
| | - Daoqin Zhang
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA94305
| | - Junhong Han
- Department of Biotherapy, Cancer Center and State Laboratory of Biotherapy, and Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, Sichuan Province610041, China
| | - Chuanhe Yu
- Hormel Institute, University of Minnesota, Austin, MN55912
| | - Haiyun Gan
- Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen518055, China
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7
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Marinov GK, Chen X, Swaffer MP, Xiang T, Grossman AR, Greenleaf WJ. Genome-wide distribution of 5-hydroxymethyluracil and chromatin accessibility in the Breviolum minutum genome. Genome Biol 2024; 25:115. [PMID: 38711126 PMCID: PMC11071213 DOI: 10.1186/s13059-024-03261-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 04/28/2024] [Indexed: 05/08/2024] Open
Abstract
BACKGROUND In dinoflagellates, a unique and extremely divergent genomic and nuclear organization has evolved. The highly unusual features of dinoflagellate nuclei and genomes include permanently condensed liquid crystalline chromosomes, primarily packaged by proteins other than histones, genes organized in very long unidirectional gene arrays, a general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. While most of these fascinating properties are originally identified in the 1970s and 1980s, they have not yet been investigated using modern genomic tools. RESULTS In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the Symbiodiniaceae dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, often coincides with the boundaries between gene arrays, and is generally correlated with decreased chromatin accessibility, the latter otherwise being largely uniform along the genome. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays. CONCLUSIONS Our results provide the first window into the 5-hmU and chromatin accessibility landscapes in dinoflagellates.
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Affiliation(s)
- Georgi K Marinov
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
| | - Xinyi Chen
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthew P Swaffer
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA.
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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Tonsager AJ, Zukowski A, Radebaugh CA, Weirich A, Stargell LA, Ramachandran S. THE HISTONE CHAPERONE SPN1 PRESERVES SUBNUCLEOSOMAL STRUCTURES AT PROMOTERS AND NUCLEOSOME POSITIONING IN OPEN READING FRAMES. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.14.585010. [PMID: 38559248 PMCID: PMC10979989 DOI: 10.1101/2024.03.14.585010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Spn1 is a multifunctional histone chaperone essential for life in eukaryotes. While previous work has elucidated regions of the protein important for its many interactions, it is unknown how these domains contribute to the maintenance of chromatin structure. Here, we employ digestion by micrococcal nuclease followed by single-stranded library preparation and sequencing (MNase-SSP) to characterize chromatin structure in yeast expressing wild-type or mutants of Spn1. We mapped nucleosome and subnucleosomal protections genome-wide, and surprisingly, we observed a genome-wide loss of subnucleosomal protection over nucleosome-depleted regions (NDRs) in the Spn1-K192N-containing strain, indicating critical functions of Spn1 in maintaining normal chromatin architecture in promoter regions. Additionally, alterations in nucleosome and hexasome positioning were observed in markedly different mutant Spn1 strains, demonstrating that multiple functions of Spn1 are required to maintain proper chromatin structure in open reading frames, particularly at higher expressed and longer genes. Taken together, our results reveal a previously unknown role of Spn1 in the maintenance of NDR architecture and deepen our understanding of Spn1-dependent chromatin maintenance over transcribed regions.
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Affiliation(s)
- Andrew J. Tonsager
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | | | - Catherine A. Radebaugh
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | | | - Laurie A. Stargell
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, U80045, USA
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Karri S, Dickinson Q, Jia J, Gan H, Wang Z, Deng Y, Yu C. The Role of Hexokinases in Epigenetic Regulation: Altered Hexokinase Expression and Chromatin Stability in Yeast. RESEARCH SQUARE 2024:rs.3.rs-3899124. [PMID: 38352584 PMCID: PMC10862943 DOI: 10.21203/rs.3.rs-3899124/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Background . Human hexokinase 2 ( HK2 ) plays an important role in regulating Warburg effect, which metabolizes glucose to lactate acid even in the presence of ample oxygen and provides intermediate metabolites to support cancer cell proliferation and tumor growth. HK2 overexpression has been observed in various types of cancers and targeting HK2 -driven Warburg effect has been suggested as a potential cancer therapeutic strategy. Given that epigenetic enzymes utilize metabolic intermediates as substrates or co-factors to carry out post-translational modification of DNA and histones in cells, we hypothesized that altering HK2 expression-mediated cellular glycolysis rates could impact the epigenome and, consequently, genome stability in yeast. To test this hypothesis, we established genetic models with different yeast hexokinase 2 ( HXK2) expression in Saccharomyces cerevisiae yeast cells and investigated the effect of HXK2 -dependent metabolism on parental nucleosome transfer, a key DNA replication-coupled epigenetic inheritance process, and chromatin stability. Results . By comparing the growth of mutant yeast cells carrying single deletion of hxk1Δ , hxk2Δ , or double-loss of hxk1Δ hxk2Δ to wild-type cells, we demonstrated that HXK2 is the dominant HXK in yeast cell growth. Surprisingly, manipulating HXK2 expression in yeast, whether through overexpression or deletion, had only a marginal impact on parental nucleosome assembly, but a noticeable trend with decrease chromatin instability. However, targeting yeast cells with 2-deoxy-D-glucose (2-DG), a HK2 inhibitor that has been proposed as an anti-cancer treatment, significantly increased chromatin instability. Conclusion . Our findings suggest that in yeast cells lacking HXK2 , alternative HXK s such as HXK1 or glucokinase 1 ( GLK1 ) play a role in supporting glycolysis at a level that adequately maintain epigenomic stability. While our study demonstrated an increase in epigenetic instability with 2-DG treatment, the observed effect seemed to occur independently of Hxk2-mediated glycolysis inhibition. Thus, additional research is needed to identify the molecular mechanism through which 2-DG influences chromatin stability.
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Park S, Athreya A, Carrizo GE, Benning NA, Mitchener MM, Bhanu NV, Garcia BA, Zhang B, Muir TW, Pearce EL, Ha T. Electrostatic encoding of genome organization principles within single native nucleosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570828. [PMID: 38106048 PMCID: PMC10723453 DOI: 10.1101/2023.12.08.570828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The eukaryotic genome, first packed into nucleosomes of about 150 bp around the histone core, is organized into euchromatin and heterochromatin, corresponding to the A and B compartments, respectively. Here, we asked if individual nucleosomes in vivo know where to go. That is, do mono-nucleosomes by themselves contain A/B compartment information, associated with transcription activity, in their biophysical properties? We purified native mono-nucleosomes to high monodispersity and used physiological concentrations of biological polyamines to determine their condensability. The chromosomal regions known to partition into A compartments have low condensability and vice versa. In silico chromatin polymer simulations using condensability as the only input showed that biophysical information needed to form compartments is all contained in single native nucleosomes and no other factors are needed. Condensability is also strongly anticorrelated with gene expression, and especially so near the promoter region and in a cell type dependent manner. Therefore, individual nucleosomes in the promoter know whether the gene is on or off, and that information is contained in their biophysical properties. Comparison with genetic and epigenetic features suggest that nucleosome condensability is a very meaningful axis onto which to project the high dimensional cellular chromatin state. Analysis of condensability using various condensing agents including those that are protein-based suggests that genome organization principle encoded into individual nucleosomes is electrostatic in nature. Polyamine depletion in mouse T cells, by either knocking out ornithine decarboxylase (ODC) or inhibiting ODC, results in hyperpolarized condensability, suggesting that when cells cannot rely on polyamines to translate biophysical properties of nucleosomes to control gene expression and 3D genome organization, they accentuate condensability contrast, which may explain dysfunction known to occur with polyamine deficiency.
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Affiliation(s)
- Sangwoo Park
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Advait Athreya
- Computational and Systems Biology Program, MIT, Cambridge, MA, 02139, USA
| | - Gustavo Ezequiel Carrizo
- Department of Oncology, The Bloomberg–Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nils A. Benning
- Department of Biology, Johns Hopkins University. Baltimore, MD 21218, USA
| | | | - Natarajan V. Bhanu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine St. Louis, St. Louis, MO 63110, USA
| | - Benjamin A. Garcia
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine St. Louis, St. Louis, MO 63110, USA
| | - Bin Zhang
- Department of Chemistry, MIT, Cambridge, MA 02139, USA
| | - Tom W. Muir
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Erika L. Pearce
- Department of Oncology, The Bloomberg–Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Biochemistry and Molecular Biology Department, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Boston, MA 02115, USA
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Biswas A, Basu A. The impact of the sequence-dependent physical properties of DNA on chromatin dynamics. Curr Opin Struct Biol 2023; 83:102698. [PMID: 37696706 DOI: 10.1016/j.sbi.2023.102698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 07/07/2023] [Accepted: 08/14/2023] [Indexed: 09/13/2023]
Abstract
The local mechanical properties of DNA depend on local sequence. Here we review recent genomic, structural, and computational efforts at deciphering the "mechanical code", i.e., the mapping between sequence and mechanics. We then discuss works that suggest how evolution has exploited the mechanical code to control the energetics of DNA-deforming biological processes such as nucleosome organization, transcription factor binding, DNA supercoiling, gene regulation, and 3D chromatin organization. As a whole, these recent works suggest that DNA sequence in diverse organisms can encode regulatory information governing diverse processes via the mechanical code.
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Affiliation(s)
- Aditi Biswas
- Department of Biosciences, Durham University, Durham, UK
| | - Aakash Basu
- Department of Biosciences, Durham University, Durham, UK.
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12
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Nikitina T, Guiblet WM, Cui F, Zhurkin VB. Histone N-tails modulate sequence-specific positioning of nucleosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.30.569460. [PMID: 38076910 PMCID: PMC10705531 DOI: 10.1101/2023.11.30.569460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
The precise mechanisms governing sequence-dependent positioning of nucleosomes on DNA remain unknown in detail. Existing algorithms, taking into account the sequence-dependent deformability of DNA and its interactions with the histone globular domains, predict rotational setting of only 65% of human nucleosomes mapped in vivo. To uncover novel factors responsible for the nucleosome positioning, we analyzed potential involvement of the histone N-tails in this process. To this aim, we reconstituted the H2A/H4 N-tailless nucleosomes on human BRCA1 DNA (~100 kb) and compared their positions and sequences with those of the wild-type nucleosomes. In the case of H2A tailless nucleosomes, the AT content of DNA sequences is changed locally at superhelical location (SHL) ±4, while maintaining the same rotational setting as their wild-type counterparts. Conversely, the H4 tailless nucleosomes display widespread changes of the AT content near SHL ±1 and SHL ±2, where the H4 N-tails interact with DNA. Furthermore, a substantial number of H4 tailless nucleosomes exhibit rotational setting opposite to that of the wild-type nucleosomes. Thus, our findings strongly suggest that the histone N-tails are operative in selection of nucleosome positions, which may have wide-ranging implications for epigenetic modulation of chromatin states.
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Affiliation(s)
- Tatiana Nikitina
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, US
| | - Wilfried M. Guiblet
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, US
| | - Feng Cui
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA
| | - Victor B. Zhurkin
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, US
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13
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Dennis AF, Xu Z, Clark DJ. Examining chromatin heterogeneity through PacBio long-read sequencing of M.EcoGII methylated genomes: an m 6A detection efficiency and calling bias correcting pipeline. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569045. [PMID: 38076871 PMCID: PMC10705563 DOI: 10.1101/2023.11.28.569045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Recent studies have combined DNA methyltransferase footprinting of genomic DNA in nuclei with long-read sequencing, resulting in detailed chromatin maps for multi-kilobase stretches of genomic DNA from one cell. Theoretically, nucleosome footprints and nucleosome-depleted regions can be identified using M.EcoGII, which methylates adenines in any sequence context, providing a high-resolution map of accessible regions in each DNA molecule. Here we report PacBio long-read sequence data for budding yeast nuclei treated with M.EcoGII and a bioinformatic pipeline which corrects for three key challenges undermining this promising method. First, detection of m6A in individual DNA molecules by the PacBio software is inefficient, resulting in false footprints predicted by random gaps of seemingly unmethylated adenines. Second, there is a strong bias against m6A base calling as AT content increases. Third, occasional methylation occurs within nucleosomes, breaking up their footprints. After correcting for these issues, our pipeline calculates a correlation coefficient-based score indicating the extent of chromatin heterogeneity within the cell population for every gene. Although the population average is consistent with that derived using other techniques, we observe a wide range of heterogeneity in nucleosome positions at the single-molecule level, probably reflecting cellular chromatin dynamics.
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Affiliation(s)
| | | | - David J. Clark
- Division of Developmental Biology, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
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14
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Lu Y, Wang S, Jiao Y. The Effects of Deregulated Ribosomal Biogenesis in Cancer. Biomolecules 2023; 13:1593. [PMID: 38002277 PMCID: PMC10669593 DOI: 10.3390/biom13111593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/04/2023] [Accepted: 10/22/2023] [Indexed: 11/26/2023] Open
Abstract
Ribosomes are macromolecular ribonucleoprotein complexes assembled from RNA and proteins. Functional ribosomes arise from the nucleolus, require ribosomal RNA processing and the coordinated assembly of ribosomal proteins (RPs), and are frequently hyperactivated to support the requirement for protein synthesis during the self-biosynthetic and metabolic activities of cancer cells. Studies have provided relevant information on targeted anticancer molecules involved in ribosome biogenesis (RiBi), as increased RiBi is characteristic of many types of cancer. The association between unlimited cell proliferation and alterations in specific steps of RiBi has been highlighted as a possible critical driver of tumorigenesis and metastasis. Thus, alterations in numerous regulators and actors involved in RiBi, particularly in cancer, significantly affect the rate and quality of protein synthesis and, ultimately, the transcriptome to generate the associated proteome. Alterations in RiBi in cancer cells activate nucleolar stress response-related pathways that play important roles in cancer-targeted interventions and immunotherapies. In this review, we focus on the association between alterations in RiBi and cancer. Emphasis is placed on RiBi deregulation and its secondary consequences, including changes in protein synthesis, loss of RPs, adaptive transcription and translation, nucleolar stress regulation, metabolic changes, and the impaired ribosome biogenesis checkpoint.
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Affiliation(s)
| | - Shizhuo Wang
- Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang 110055, China;
| | - Yisheng Jiao
- Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang 110055, China;
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15
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Marinov GK, Chen X, Swaffer MP, Xiang T, Grossman AR, Greenleaf WJ. Genome-wide distribution of 5-hydroxymethyluracil and chromatin accessibility in the Breviolum minutum genome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558303. [PMID: 37781619 PMCID: PMC10541103 DOI: 10.1101/2023.09.18.558303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
In dinoflagellates, a unique and extremely divergent genomic and nuclear organization has evolved. The highly unusual features of dinoflagellate nuclei and genomes include permanently condensed liquid crystalline chromosomes, primarily packaged by proteins other than histones, genes organized in very long unidirectional gene arrays, a general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. While most of these fascinating properties were originally identified in the 1970s and 1980s, they have not yet been investigated using modern genomic tools. In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the Symbiodiniaceae dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, often coincides with the boundaries between gene arrays, and is generally correlated with decreased chromatin accessibility, the latter otherwise being largely uniform along the genome. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays.
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Affiliation(s)
- Georgi K Marinov
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Xinyi Chen
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
| | | | - Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University, Stanford, California 94305, USA
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, California 94305, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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16
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Yadav M, Zuiddam M, Schiessel H. The role of transcript regions and amino acid choice in nucleosome positioning. NAR Genom Bioinform 2023; 5:lqad080. [PMID: 37705829 PMCID: PMC10495542 DOI: 10.1093/nargab/lqad080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/19/2023] [Accepted: 08/30/2023] [Indexed: 09/15/2023] Open
Abstract
Eukaryotic DNA is organized and compacted in a string of nucleosomes, DNA-wrapped protein cylinders. The positions of nucleosomes along DNA are not random but show well-known base pair sequence preferences that result from the sequence-dependent elastic and geometric properties of the DNA double helix. Here, we focus on DNA around transcription start sites, which are known to typically attract nucleosomes in multicellular life forms through their high GC content. We aim to understand how these GC signals, as observed in genome-wide averages, are produced and encoded through different genomic regions (mainly 5' UTRs, coding exons, and introns). Our study uses a bioinformatics approach to decompose the genome-wide GC signal into between-region and within-region signals. We find large differences in GC signal contributions between vertebrates and plants and, remarkably, even between closely related species. Introns contribute most to the GC signal in vertebrates, while in plants the exons dominate. Further, we find signal strengths stronger on DNA than on mRNA, suggesting a biological function of GC signals along the DNA itself, as is the case for nucleosome positioning. Finally, we make the surprising discovery that both the choice of synonymous codons and amino acids contribute to the nucleosome positioning signal.
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Affiliation(s)
- Manish Yadav
- Cluster of Excellence Physics of Life, TU Dresden, 01062 Dresden, Germany
| | - Martijn Zuiddam
- Institute Lorentz for Theoretical Physics, Leiden University, Leiden, the Netherlands
| | - Helmut Schiessel
- Cluster of Excellence Physics of Life, TU Dresden, 01062 Dresden, Germany
- Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany
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17
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Smerdon MJ, Wyrick JJ, Delaney S. A half century of exploring DNA excision repair in chromatin. J Biol Chem 2023; 299:105118. [PMID: 37527775 PMCID: PMC10498010 DOI: 10.1016/j.jbc.2023.105118] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/03/2023] Open
Abstract
DNA in eukaryotic cells is packaged into the compact and dynamic structure of chromatin. This packaging is a double-edged sword for DNA repair and genomic stability. Chromatin restricts the access of repair proteins to DNA lesions embedded in nucleosomes and higher order chromatin structures. However, chromatin also serves as a signaling platform in which post-translational modifications of histones and other chromatin-bound proteins promote lesion recognition and repair. Similarly, chromatin modulates the formation of DNA damage, promoting or suppressing lesion formation depending on the chromatin context. Therefore, the modulation of DNA damage and its repair in chromatin is crucial to our understanding of the fate of potentially mutagenic and carcinogenic lesions in DNA. Here, we survey many of the landmark findings on DNA damage and repair in chromatin over the last 50 years (i.e., since the beginning of this field), focusing on excision repair, the first repair mechanism studied in the chromatin landscape. For example, we highlight how the impact of chromatin on these processes explains the distinct patterns of somatic mutations observed in cancer genomes.
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Affiliation(s)
- Michael J Smerdon
- Biochemistry and Biophysics, School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
| | - John J Wyrick
- Genetics and Cell Biology, School of Molecular Biosciences, Washington State University, Pullman, Washington, USA
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, Rhode Island, USA
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18
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Tan ZY, Cai S, Noble AJ, Chen JK, Shi J, Gan L. Heterogeneous non-canonical nucleosomes predominate in yeast cells in situ. eLife 2023; 12:RP87672. [PMID: 37503920 PMCID: PMC10382156 DOI: 10.7554/elife.87672] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023] Open
Abstract
Nuclear processes depend on the organization of chromatin, whose basic units are cylinder-shaped complexes called nucleosomes. A subset of mammalian nucleosomes in situ (inside cells) resembles the canonical structure determined in vitro 25 years ago. Nucleosome structure in situ is otherwise poorly understood. Using cryo-electron tomography (cryo-ET) and 3D classification analysis of budding yeast cells, here we find that canonical nucleosomes account for less than 10% of total nucleosomes expected in situ. In a strain in which H2A-GFP is the sole source of histone H2A, class averages that resemble canonical nucleosomes both with and without GFP densities are found ex vivo (in nuclear lysates), but not in situ. These data suggest that the budding yeast intranuclear environment favors multiple non-canonical nucleosome conformations. Using the structural observations here and the results of previous genomics and biochemical studies, we propose a model in which the average budding yeast nucleosome's DNA is partially detached in situ.
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Affiliation(s)
- Zhi Yang Tan
- Department of Biological Sciences and Center for BioImaging Sciences, National University of SingaporeSingaporeSingapore
| | - Shujun Cai
- Department of Biological Sciences and Center for BioImaging Sciences, National University of SingaporeSingaporeSingapore
| | - Alex J Noble
- National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology CenterNew YorkUnited States
| | - Jon K Chen
- Department of Biological Sciences and Center for BioImaging Sciences, National University of SingaporeSingaporeSingapore
| | - Jian Shi
- Department of Biological Sciences and Center for BioImaging Sciences, National University of SingaporeSingaporeSingapore
| | - Lu Gan
- Department of Biological Sciences and Center for BioImaging Sciences, National University of SingaporeSingaporeSingapore
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19
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Yague-Sanz C, Migeot V, Larochelle M, Bachand F, Wéry M, Morillon A, Hermand D. Chromatin remodeling by Pol II primes efficient Pol III transcription. Nat Commun 2023; 14:3587. [PMID: 37328480 PMCID: PMC10276017 DOI: 10.1038/s41467-023-39387-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 06/09/2023] [Indexed: 06/18/2023] Open
Abstract
The packaging of the genetic material into chromatin imposes the remodeling of this barrier to allow efficient transcription. RNA polymerase II activity is coupled with several histone modification complexes that enforce remodeling. How RNA polymerase III (Pol III) counteracts the inhibitory effect of chromatin is unknown. We report here a mechanism where RNA Polymerase II (Pol II) transcription is required to prime and maintain nucleosome depletion at Pol III loci and contributes to efficient Pol III recruitment upon re-initiation of growth from stationary phase in Fission yeast. The Pcr1 transcription factor participates in the recruitment of Pol II, which affects local histone occupancy through the associated SAGA complex and a Pol II phospho-S2 CTD / Mst2 pathway. These data expand the central role of Pol II in gene expression beyond mRNA synthesis.
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Affiliation(s)
- Carlo Yague-Sanz
- URPHYM-GEMO, The University of Namur, rue de Bruxelles, 61, Namur, 5000, Belgium
| | - Valérie Migeot
- URPHYM-GEMO, The University of Namur, rue de Bruxelles, 61, Namur, 5000, Belgium
| | - Marc Larochelle
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, QC, J1E 4K8, Canada
| | - François Bachand
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, QC, J1E 4K8, Canada
| | - Maxime Wéry
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, PSL Research University, Université Pierre et Marie Curie, CNRS UMR 3244, Paris, France
| | - Antonin Morillon
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, PSL Research University, Université Pierre et Marie Curie, CNRS UMR 3244, Paris, France
| | - Damien Hermand
- URPHYM-GEMO, The University of Namur, rue de Bruxelles, 61, Namur, 5000, Belgium.
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20
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Gvozdenov Z, Barcutean Z, Struhl K. Functional analysis of a random-sequence chromosome reveals a high level and the molecular nature of transcriptional noise in yeast cells. Mol Cell 2023; 83:1786-1797.e5. [PMID: 37137302 PMCID: PMC10247422 DOI: 10.1016/j.molcel.2023.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/18/2023] [Accepted: 04/10/2023] [Indexed: 05/05/2023]
Abstract
We measure transcriptional noise in yeast by analyzing chromatin structure and transcription of an 18-kb region of DNA whose sequence was randomly generated. Nucleosomes fully occupy random-sequence DNA, but nucleosome-depleted regions (NDRs) are much less frequent, and there are fewer well-positioned nucleosomes and shorter nucleosome arrays. Steady-state levels of random-sequence RNAs are comparable to yeast mRNAs, although transcription and decay rates are higher. Transcriptional initiation from random-sequence DNA occurs at numerous sites, indicating very low intrinsic specificity of the RNA Pol II machinery. In contrast, poly(A) profiles of random-sequence RNAs are roughly comparable to those of yeast mRNAs, suggesting limited evolutionary restraints on poly(A) site choice. Random-sequence RNAs show higher cell-to-cell variability than yeast mRNAs, suggesting that functional elements limit variability. These observations indicate that transcriptional noise occurs at high levels in yeast, and they provide insight into how chromatin and transcription patterns arise from the evolved yeast genome.
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Affiliation(s)
- Zlata Gvozdenov
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Zeno Barcutean
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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21
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Bohm KA, Morledge-Hampton B, Stevison S, Mao P, Roberts SA, Wyrick JJ. Genome-wide maps of rare and atypical UV photoproducts reveal distinct patterns of damage formation and mutagenesis in yeast chromatin. Proc Natl Acad Sci U S A 2023; 120:e2216907120. [PMID: 36853943 PMCID: PMC10013872 DOI: 10.1073/pnas.2216907120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/03/2023] [Indexed: 03/01/2023] Open
Abstract
Ultraviolet (UV) light induces different classes of mutagenic photoproducts in DNA, namely cyclobutane pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and atypical thymine-adenine photoproducts (TA-PPs). CPD formation is modulated by nucleosomes and transcription factors (TFs), which has important ramifications for Ultraviolet (UV) mutagenesis. How chromatin affects the formation of 6-4PPs and TA-PPs is unclear. Here, we use UV damage endonuclease-sequencing (UVDE-seq) to map these UV photoproducts across the yeast genome. Our results indicate that nucleosomes, the fundamental building block of chromatin, have opposing effects on photoproduct formation. Nucleosomes induce CPDs and 6-4PPs at outward rotational settings in nucleosomal DNA but suppress TA-PPs at these settings. Our data also indicate that DNA binding by different classes of yeast TFs causes lesion-specific hotspots of 6-4PPs or TA-PPs. For example, DNA binding by the TF Rap1 generally suppresses CPD and 6-4PP formation but induces a TA-PP hotspot. Finally, we show that 6-4PP formation is strongly induced at the binding sites of TATA-binding protein (TBP), which is correlated with higher mutation rates in UV-exposed yeast. These results indicate that the formation of 6-4PPs and TA-PPs is modulated by chromatin differently than CPDs and that this may have important implications for UV mutagenesis.
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Affiliation(s)
- Kaitlynne A. Bohm
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
| | | | - Scott Stevison
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
| | - Peng Mao
- Department of Internal Medicine, University of New Mexico Comprehensive Cancer Center, Albuquerque, NM87131
| | - Steven A. Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
- Center for Reproductive Biology, Washington State University, Pullman, WA99164
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
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22
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The Hypersaline Archaeal Histones HpyA and HstA Are DNA Binding Proteins That Defy Categorization According to Commonly Used Functional Criteria. mBio 2023; 14:e0344922. [PMID: 36779711 PMCID: PMC10128011 DOI: 10.1128/mbio.03449-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Histone proteins are found across diverse lineages of Archaea, many of which package DNA and form chromatin. However, previous research has led to the hypothesis that the histone-like proteins of high-salt-adapted archaea, or halophiles, function differently. The sole histone protein encoded by the model halophilic species Halobacterium salinarum, HpyA, is nonessential and expressed at levels too low to enable genome-wide DNA packaging. Instead, HpyA mediates the transcriptional response to salt stress. Here we compare the features of genome-wide binding of HpyA to those of HstA, the sole histone of another model halophile, Haloferax volcanii. hstA, like hpyA, is a nonessential gene. To better understand HpyA and HstA functions, protein-DNA binding data (chromatin immunoprecipitation sequencing [ChIP-seq]) of these halophilic histones are compared to publicly available ChIP-seq data from DNA binding proteins across all domains of life, including transcription factors (TFs), nucleoid-associated proteins (NAPs), and histones. These analyses demonstrate that HpyA and HstA bind the genome infrequently in discrete regions, which is similar to TFs but unlike NAPs, which bind a much larger genomic fraction. However, unlike TFs that typically bind in intergenic regions, HpyA and HstA binding sites are located in both coding and intergenic regions. The genome-wide dinucleotide periodicity known to facilitate histone binding was undetectable in the genomes of both species. Instead, TF-like and histone-like binding sequence preferences were detected for HstA and HpyA, respectively. Taken together, these data suggest that halophilic archaeal histones are unlikely to facilitate genome-wide chromatin formation and that their function defies categorization as a TF, NAP, or histone. IMPORTANCE Most cells in eukaryotic species-from yeast to humans-possess histone proteins that pack and unpack DNA in response to environmental cues. These essential proteins regulate genes necessary for important cellular processes, including development and stress protection. Although the histone fold domain originated in the domain of life Archaea, the function of archaeal histone-like proteins is not well understood relative to those of eukaryotes. We recently discovered that, unlike histones of eukaryotes, histones in hypersaline-adapted archaeal species do not package DNA and can act as transcription factors (TFs) to regulate stress response gene expression. However, the function of histones across species of hypersaline-adapted archaea still remains unclear. Here, we compare hypersaline histone function to a variety of DNA binding proteins across the tree of life, revealing histone-like behavior in some respects and specific transcriptional regulatory function in others.
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23
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Karri S, Yang Y, Zhou J, Dickson Q, Wang Z, Gan H, Yu C. Defective transfer of parental histone decreases frequency of homologous recombination in budding yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.10.523501. [PMID: 36711718 PMCID: PMC9882084 DOI: 10.1101/2023.01.10.523501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Recycling of parental histones is an important step in epigenetic inheritance. During DNA replication, DNA polymerase epsilon subunit DPB3/DPB4 and DNA replication helicase subunit MCM2 are involved in the transfer of parental histones to the leading and lagging DNA strands, respectively. Single Dpb3 deletion ( dpb3Δ ) or Mcm2 mutation ( mcm2-3A ), which each disrupt one parental histone transfer pathway, leads to the other's predominance. However, the impact of the two histone transfer pathways on chromatin structure and DNA repair remains elusive. In this study, we used budding yeast Saccharomyces cerevisiae to determine the genetic and epigenetic outcomes from disruption of parental histone H3-H4 tetramer transfer. We found that a dpb3Δ / mcm2-3A double mutant did not exhibit the single dpb3Δ and mcm2-3A mutants' asymmetric parental histone patterns, suggesting that the processes by which parental histones are transferred to the leading and lagging strands are independent. Surprisingly, the frequency of homologous recombination was significantly lower in dpb3Δ, mcm2-3A , and dpb3Δ / mcm2-3A mutants relative to the wild-type strain, likely due to the elevated levels of free histones detected in the mutant cells. Together, these findings indicate that proper transfer of parental histones to the leading and lagging strands during DNA replication is essential for maintaining chromatin structure and that high levels of free histones due to parental histone transfer defects are detrimental to cells.
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24
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Khan SR, Sakib S, Rahman MS, Samee MAH. DeepBend: An interpretable model of DNA bendability. iScience 2023; 26:105945. [PMID: 36866046 PMCID: PMC9971889 DOI: 10.1016/j.isci.2023.105945] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 12/05/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023] Open
Abstract
The bendability of genomic DNA impacts chromatin packaging and protein-DNA binding. However, we do not have a comprehensive understanding of the motifs influencing DNA bendability. Recent high-throughput technologies such as Loop-Seq offer an opportunity to address this gap but the lack of accurate and interpretable machine learning models still remains. Here we introduce DeepBend, a convolutional neural network model with convolutions designed to directly capture the motifs underlying DNA bendability and their periodic occurrences or relative arrangements that modulate bendability. DeepBend consistently performs on par with alternative models while giving an extra edge through mechanistic interpretations. Besides confirming the known motifs of DNA bendability, DeepBend also revealed several novel motifs and showed how the spatial patterns of motif occurrences influence bendability. DeepBend's genome-wide prediction of bendability further showed how bendability is linked to chromatin conformation and revealed the motifs controlling the bendability of topologically associated domains and their boundaries.
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Affiliation(s)
- Samin Rahman Khan
- Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Sadman Sakib
- Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - M. Sohel Rahman
- Bangladesh University of Engineering and Technology, Dhaka, Bangladesh,Corresponding author
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25
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Basu A, Bobrovnikov DG, Cieza B, Arcon JP, Qureshi Z, Orozco M, Ha T. Deciphering the mechanical code of the genome and epigenome. Nat Struct Mol Biol 2022; 29:1178-1187. [PMID: 36471057 PMCID: PMC10142808 DOI: 10.1038/s41594-022-00877-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/18/2022] [Indexed: 12/12/2022]
Abstract
Diverse DNA-deforming processes are impacted by the local mechanical and structural properties of DNA, which in turn depend on local sequence and epigenetic modifications. Deciphering this mechanical code (that is, this dependence) has been challenging due to the lack of high-throughput experimental methods. Here we present a comprehensive characterization of the mechanical code. Utilizing high-throughput measurements of DNA bendability via loop-seq, we quantitatively established how the occurrence and spatial distribution of dinucleotides, tetranucleotides and methylated CpG impact DNA bendability. We used our measurements to develop a physical model for the sequence and methylation dependence of DNA bendability. We validated the model by performing loop-seq on mouse genomic sequences around transcription start sites and CTCF-binding sites. We applied our model to test the predictions of all-atom molecular dynamics simulations and to demonstrate that sequence and epigenetic modifications can mechanically encode regulatory information in diverse contexts.
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Affiliation(s)
- Aakash Basu
- Department of Biosciences, Durham University, Durham, UK. .,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Dmitriy G Bobrovnikov
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Basilio Cieza
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Juan Pablo Arcon
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Zan Qureshi
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, Barcelona, Spain.,Department of Biochemistry and Biomedicine, Universitat de Barcelona, Barcelona, Spain
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA. .,Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA. .,Howard Hughes Medical Institute, Baltimore, MD, USA.
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26
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Mansisidor AR, Risca VI. Chromatin accessibility: methods, mechanisms, and biological insights. Nucleus 2022; 13:236-276. [PMID: 36404679 PMCID: PMC9683059 DOI: 10.1080/19491034.2022.2143106] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/23/2022] [Accepted: 10/30/2022] [Indexed: 11/22/2022] Open
Abstract
Access to DNA is a prerequisite to the execution of essential cellular processes that include transcription, replication, chromosomal segregation, and DNA repair. How the proteins that regulate these processes function in the context of chromatin and its dynamic architectures is an intensive field of study. Over the past decade, genome-wide assays and new imaging approaches have enabled a greater understanding of how access to the genome is regulated by nucleosomes and associated proteins. Additional mechanisms that may control DNA accessibility in vivo include chromatin compaction and phase separation - processes that are beginning to be understood. Here, we review the ongoing development of accessibility measurements, we summarize the different molecular and structural mechanisms that shape the accessibility landscape, and we detail the many important biological functions that are linked to chromatin accessibility.
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Affiliation(s)
- Andrés R. Mansisidor
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
| | - Viviana I. Risca
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
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27
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Saleh MM, Hundley HA, Zentner GE. Involvement of the SAGA and TFIID coactivator complexes in transcriptional dysregulation caused by the separation of core and tail Mediator modules. G3 (BETHESDA, MD.) 2022; 12:jkac290. [PMID: 36331351 PMCID: PMC9713439 DOI: 10.1093/g3journal/jkac290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 09/28/2022] [Indexed: 02/17/2024]
Abstract
Regulation of RNA polymerase II transcription requires the concerted efforts of several multisubunit coactivator complexes, which interact with the RNA polymerase II preinitiation complex to stimulate transcription. We previously showed that separation of the Mediator core from Mediator's tail module results in modest overactivation of genes annotated as highly dependent on TFIID for expression. However, it is unclear if other coactivators are involved in this phenomenon. Here, we show that the overactivation of certain genes by Mediator core/tail separation is blunted by disruption of the Spt-Ada-Gcn5-Acetyl transferase complex through the removal of its structural Spt20 subunit, though this downregulation does not appear to completely depend on reduced Spt-Ada-Gcn5-Acetyl transferase association with the genome. Consistent with the enrichment of TFIID-dependent genes among genes overactivated by Mediator core/tail separation, depletion of the essential TFIID subunit Taf13 suppressed the overactivation of these genes when Med16 was simultaneously removed. As with Spt-Ada-Gcn5-Acetyl transferase, this effect did not appear to be fully dependent on the reduced genomic association of TFIID. Given that the observed changes in gene expression could not be clearly linked to alterations in Spt-Ada-Gcn5-Acetyl transferase or TFIID occupancy, our data may suggest that the Mediator core/tail connection is important for the modulation of Spt-Ada-Gcn5-Acetyl transferase and/or TFIID conformation and/or function at target genes.
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Affiliation(s)
- Moustafa M Saleh
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Heather A Hundley
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Gabriel E Zentner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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28
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DNA Sequence-Dependent Properties of Nucleosome Positioning in Regions of Distinct Chromatin States in Mouse Embryonic Stem Cells. Int J Mol Sci 2022; 23:ijms232214488. [PMID: 36430966 PMCID: PMC9693356 DOI: 10.3390/ijms232214488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/18/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022] Open
Abstract
Chromatin architecture is orchestrated, and plays crucial roles during the developmental process by regulating gene expression. In embryonic stem cells (ESCs), three types of chromatin states, including active, repressive and poised states, were previously identified and characterized with specific chromatin modification marks and different transcription activity, but it is largely unknown how nucleosomes are organized in these chromatin states. In this study, by using a DNA deformation energy model, we investigated the sequence-dependent nucleosome organization within the chromatin states in mouse ESCs. The results revealed that: (1) compared with poised genes, active genes are characterized with a higher level of nucleosome occupancy around their transcription start sites (TSS) and transcription termination sites (TTS), and both types of genes do not have a nucleosome-depleted region at their TTS, contrasting with the MNase-seq based result; (2) based on our previous DNA bending energy model, we developed an improved model capable of predicting both rotational positioning and nucleosome occupancy determined by a chemical mapping approach; (3) DNA bending-energy-based analyses demonstrated that the fragile nucleosomes positioned at both gene ends could be explained largely by enhanced rotational positioning signals encoded in DNA, but nucleosome phasing around the TSS of active genes was not determined by sequence preference; (4) the nucleosome occupancy landscape around the binding sites of some developmentally important transcription factors known to bind with different chromatin contexts, was also successfully predicted; (5) the difference of nucleosome occupancy around the TSS between CpG-rich and CpG-poor promoters was partly captured by our sequence-dependent model. Taken together, by developing an improved deformation-energy-based model, we revealed some sequence-dependent properties of the nucleosome arrangements in regions of distinct chromatin states in mouse ESCs.
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29
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Henikoff S, Ahmad K. In situ tools for chromatin structural epigenomics. Protein Sci 2022; 31:e4458. [PMID: 36170035 PMCID: PMC9601787 DOI: 10.1002/pro.4458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/19/2022] [Accepted: 09/22/2022] [Indexed: 12/14/2022]
Abstract
Technological progress over the past 15 years has fueled an explosion in genome-wide chromatin profiling tools that take advantage of low-cost short-read sequencing technologies to map particular chromatin features. Here, we survey the recent development of epigenomic tools that provide precise positions of chromatin proteins genome-wide in intact cells or nuclei. Some profiling tools are based on tethering Micrococcal Nuclease to chromatin proteins of interest in situ, whereas others similarly tether Tn5 transposase to integrate DNA sequencing adapters (tagmentation) and so eliminate the need for library preparation. These in situ cleavage and tagmentation tools have gained in popularity over the past few years, with many protocol enhancements and adaptations for single-cell and spatial chromatin profiling. The application of experimental and computational tools to address problems in gene regulation, eukaryotic development, and human disease are helping to define the emerging field of chromatin structural epigenomics.
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Affiliation(s)
- Steven Henikoff
- Fred Hutchinson Cancer CenterSeattleWashingtonUSA
- Howard Hughes Medical InstituteChevy ChaseMarylandUSA
| | - Kami Ahmad
- Fred Hutchinson Cancer CenterSeattleWashingtonUSA
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30
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Kondalaji SG, Bowman GD. In Vitro Mapping of Nucleosome Positions at Base-Pair Resolution Using Ortho-Phenanthroline. Curr Protoc 2022; 2:e518. [PMID: 35943282 PMCID: PMC9373710 DOI: 10.1002/cpz1.518] [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] [Indexed: 06/15/2023]
Abstract
The positions of nucleosomes along genomic DNA play a role in defining patterns of gene expression and chromatin organization. Determination of nucleosome positions in vivo and in vitro, as revealed by the locations of histones on DNA, has provided insight into mechanisms of nucleosome sliding, spacing, assembly, and disassembly. Here, we describe methods for the in vitro determination of histone-DNA contacts at base-pair (bp) resolution. The protocol involves the labeling of histones with ortho-phenanthroline (OP), site-specific cleavage of nucleosomal DNA, and processing and analysis of the resulting DNA fragments. This methodology provides an efficient and high-resolution means for studying kinetics and behavior of enzymes that alter nucleosome structure and/or positioning, and can be used to identify preferred distributions of nucleosomes on natural DNA sequences. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Cysteine-specific chemical modification of folded histones with ortho-phenanthroline (OP) Basic Protocol 2: Nucleosome sliding assay adapted for OP mapping of histone-DNA contacts Basic Protocol 3: OP-mediated cleavage, processing, and analysis of DNA fragments using a sequencing gel Support Protocol 1: Preparation of dideoxy sequencing ladders Support Protocol 2: Preparation and running of a denaturing DNA sequencing gel.
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Affiliation(s)
| | - Gregory D Bowman
- T. C. Jenkins Department of Biophysics, Johns Hopkins
University, Baltimore, Maryland 21218
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31
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Kadam S, Bameta T, Padinhateeri R. Nucleosome sliding can influence the spreading of histone modifications. Phys Rev E 2022; 106:024408. [PMID: 36110002 DOI: 10.1103/physreve.106.024408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Nucleosomes are the fundamental building blocks of chromatin that not only help in the folding of chromatin, but also in carrying epigenetic information. It is known that nucleosome sliding is responsible for dynamically organizing chromatin structure and the resulting gene regulation. Since sliding can move two neighboring nucleosomes physically close or away, can it play a role in the spreading of histone modifications? We investigate this by simulating a stochastic model that couples nucleosome dynamics with the kinetics of histone modifications. We show that the sliding of nucleosomes can affect the modification pattern as well as the time it takes to modify a given region of chromatin. Exploring different nucleosome densities and modification kinetic parameters, we show that nucleosome sliding can be important for creating histone modification domains. Our model predicts that nucleosome density coupled with sliding dynamics can create an asymmetric histone modification profile around regulatory regions. We also compute the probability distribution of modified nucleosomes and relaxation kinetics of modifications. Our predictions are comparable with known experimental results.
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Affiliation(s)
- Shantanu Kadam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Tripti Bameta
- Department of Medical Oncology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai 410210, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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32
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Huang Y, Wang B, Liu J. NucleoMap: A computational tool for identifying nucleosomes in ultra-high resolution contact maps. PLoS Comput Biol 2022; 18:e1010265. [PMID: 35834552 PMCID: PMC9321407 DOI: 10.1371/journal.pcbi.1010265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 07/26/2022] [Accepted: 05/30/2022] [Indexed: 11/18/2022] Open
Abstract
Although poorly positioned nucleosomes are ubiquitous in the eukaryotic genome, they are difficult to identify with existing nucleosome identification methods. Recently available enhanced high-throughput chromatin conformation capture techniques such as Micro-C, DNase Hi-C, and Hi-CO characterize nucleosome-level chromatin proximity, probing the positions of mono-nucleosomes and the spacing between nucleosome pairs at the same time, enabling nucleosome profiling in poorly positioned regions. Here we develop a novel computational approach, NucleoMap, to identify nucleosome positioning from ultra-high resolution chromatin contact maps. By integrating nucleosome read density, contact distances, and binding preferences, NucleoMap precisely locates nucleosomes in both prokaryotic and eukaryotic genomes and outperforms existing nucleosome identification methods in both precision and recall. We rigorously characterize genome-wide association in eukaryotes between the spatial organization of mono-nucleosomes and their corresponding histone modifications, protein binding activities, and higher-order chromatin functions. We also find evidence of two tetra-nucleosome folding structures in human embryonic stem cells and analyze their association with multiple structural and functional regions. Based on the identified nucleosomes, nucleosome contact maps are constructed, reflecting the inter-nucleosome distances and preserving the contact distance profiles in original contact maps.
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Affiliation(s)
- Yuanhao Huang
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bingjiang Wang
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jie Liu
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Computer Science & Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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33
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Hsieh LJ, Gourdet MA, Moore CM, Muñoz EN, Gamarra N, Ramani V, Narlikar GJ. A hexasome is the preferred substrate for the INO80 chromatin remodeling complex, allowing versatility of function. Mol Cell 2022; 82:2098-2112.e4. [PMID: 35597239 PMCID: PMC9351570 DOI: 10.1016/j.molcel.2022.04.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 12/10/2021] [Accepted: 04/20/2022] [Indexed: 10/18/2022]
Abstract
The critical role of the INO80 chromatin remodeling complex in transcription is commonly attributed to its nucleosome sliding activity. Here, we have found that INO80 prefers to mobilize hexasomes over nucleosomes. INO80's preference for hexasomes reaches up to ∼60 fold when flanking DNA overhangs approach ∼18-bp linkers in yeast gene bodies. Correspondingly, deletion of INO80 significantly affects the positions of hexasome-sized particles within yeast genes in vivo. Our results raise the possibility that INO80 promotes nucleosome sliding by dislodging an H2A-H2B dimer, thereby making a nucleosome transiently resemble a hexasome. We propose that this mechanism allows INO80 to rapidly mobilize nucleosomes at promoters and hexasomes within gene bodies. Rapid repositioning of hexasomes that are generated in the wake of transcription may mitigate spurious transcription. More generally, such versatility may explain how INO80 regulates chromatin architecture during the diverse processes of transcription, replication, and repair.
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Affiliation(s)
- Laura J Hsieh
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Muryam A Gourdet
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Camille M Moore
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Elise N Muñoz
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Nathan Gamarra
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Vijay Ramani
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
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34
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Sun DA, Bredeson JV, Bruce HS, Patel NH. Identification and classification of cis-regulatory elements in the amphipod crustacean Parhyale hawaiensis. Development 2022; 149:275484. [PMID: 35608283 DOI: 10.1242/dev.200793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/21/2022] [Indexed: 12/13/2022]
Abstract
Emerging research organisms enable the study of biology that cannot be addressed using classical 'model' organisms. New data resources can accelerate research in such animals. Here, we present new functional genomic resources for the amphipod crustacean Parhyale hawaiensis, facilitating the exploration of gene regulatory evolution using this emerging research organism. We use Omni-ATAC-seq to identify accessible chromatin genome-wide across a broad time course of Parhyale embryonic development. This time course encompasses many major morphological events, including segmentation, body regionalization, gut morphogenesis and limb development. In addition, we use short- and long-read RNA-seq to generate an improved Parhyale genome annotation, enabling deeper classification of identified regulatory elements. We discover differential accessibility, predict nucleosome positioning, infer transcription factor binding, cluster peaks based on accessibility dynamics, classify biological functions and correlate gene expression with accessibility. Using a Minos transposase reporter system, we demonstrate the potential to identify novel regulatory elements using this approach. This work provides a platform for the identification of novel developmental regulatory elements in Parhyale, and offers a framework for performing such experiments in other emerging research organisms.
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Affiliation(s)
- Dennis A Sun
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jessen V Bredeson
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | | | - Nipam H Patel
- Marine Biological Laboratory, Woods Hole, MA 02543, USA.,Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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35
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Heldrich J, Milano CR, Markowitz TE, Ur S, Vale-Silva L, Corbett K, Hochwagen A. Two pathways drive meiotic chromosome axis assembly in Saccharomyces cerevisiae. Nucleic Acids Res 2022; 50:4545-4556. [PMID: 35412621 PMCID: PMC9071447 DOI: 10.1093/nar/gkac227] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/18/2022] [Accepted: 03/24/2022] [Indexed: 12/16/2022] Open
Abstract
Successful meiotic recombination, and thus fertility, depends on conserved axis proteins that organize chromosomes into arrays of anchored chromatin loops and provide a protected environment for DNA exchange. Here, we show that the stereotypic chromosomal distribution of axis proteins in Saccharomyces cerevisiae is the additive result of two independent pathways: a cohesin-dependent pathway, which was previously identified and mediates focal enrichment of axis proteins at gene ends, and a parallel cohesin-independent pathway that recruits axis proteins to broad genomic islands with high gene density. These islands exhibit elevated markers of crossover recombination as well as increased nucleosome density, which we show is a direct consequence of the underlying DNA sequence. A predicted PHD domain in the center of the axis factor Hop1 specifically mediates cohesin-independent axis recruitment. Intriguingly, other chromosome organizers, including cohesin, condensin, and topoisomerases, are differentially depleted from the same regions even in non-meiotic cells, indicating that these DNA sequence-defined chromatin islands exert a general influence on the patterning of chromosome structure.
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Affiliation(s)
- Jonna Heldrich
- Department of Biology, New York University, New York, NY 10003, USA
| | - Carolyn R Milano
- Department of Biology, New York University, New York, NY 10003, USA
| | | | - Sarah N Ur
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Kevin D Corbett
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
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36
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Liu J, Zhou D, Jin W. Prediction of nucleosome dynamic interval based on long short-term memory network (LSTM). J Bioinform Comput Biol 2022; 20:2250009. [DOI: 10.1142/s0219720022500093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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37
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Trotta E. GC content strongly influences the role of poly(dA) in the intrinsic nucleosome positioning in Saccharomyces cerevisiae. Yeast 2022; 39:262-271. [PMID: 35348238 PMCID: PMC9541940 DOI: 10.1002/yea.3701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 11/08/2022] Open
Abstract
The nucleosome is the basic structural element of genomic DNA packaging and plays a role in transcription, replication, and recombination. Poly(dA) tracts are considered major sequence determinants of nucleosome positioning, although their role is not well understood. Here, we show that the homopolymeric character and the low GC content of poly(dA)s play different roles in nucleosome formation. We found that the inherent low GC content of poly(dA) alone can account for the deep and anisotropic nucleosome depletion at structurally and functionally important regions of promoters and origins of replication. We also show that the level of nucleosome occupancy at poly(dA) is strongly related to the local nucleotide background and its high frequency of occurrence in Saccharomyces cerevisiae does not appear merely to be associated with its intrinsic nucleosome-excluding properties. In addition, we show that the GC content alone can predict more than 60% of the in vitro nucleosome map, providing further evidence that the intrinsic nucleosome positioning is more greatly determined by GC content than poly(dA) stretches. Our results are consistent with a model in which poly(dA) stretches act at two distinct levels: first, by its low GC content, which intrinsically contributes to hinder nucleosome formation, and second, by its contiguous runs of dA that selectively drive the recruitment of non-histone proteins with structural and functional roles.
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Affiliation(s)
- Edoardo Trotta
- Institute of Translational Pharmacology, Consiglio Nazionale delle Ricerche (CNR), Rome, Italy
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38
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Ahmad K, Henikoff S, Ramachandran S. Managing the Steady State Chromatin Landscape by Nucleosome Dynamics. Annu Rev Biochem 2022; 91:183-195. [PMID: 35303789 DOI: 10.1146/annurev-biochem-032620-104508] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gene regulation arises out of dynamic competition between nucleosomes, transcription factors, and other chromatin proteins for the opportunity to bind genomic DNA. The timescales of nucleosome assembly and binding of factors to DNA determine the outcomes of this competition at any given locus. Here, we review how these properties of chromatin proteins and the interplay between the dynamics of different factors are critical for gene regulation. We discuss how molecular structures of large chromatin-associated complexes, kinetic measurements, and high resolution mapping of protein-DNA complexes in vivo set the boundary conditions for chromatin dynamics, leading to models of how the steady state behaviors of regulatory elements arise. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Kami Ahmad
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA;
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA; .,Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics and RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado, USA
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39
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Nucleosome positioning on large tandem DNA repeats of the ’601’ sequence engineered in Saccharomyces cerevisiae. J Mol Biol 2022; 434:167497. [DOI: 10.1016/j.jmb.2022.167497] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 12/13/2022]
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40
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Marinov GK, Shipony Z, Kundaje A, Greenleaf WJ. Single-Molecule Multikilobase-Scale Profiling of Chromatin Accessibility Using m6A-SMAC-Seq and m6A-CpG-GpC-SMAC-Seq. Methods Mol Biol 2022; 2458:269-298. [PMID: 35103973 PMCID: PMC9531602 DOI: 10.1007/978-1-0716-2140-0_15] [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] [Indexed: 06/14/2023]
Abstract
A hallmark feature of active cis-regulatory elements (CREs) in eukaryotes is their nucleosomal depletion and, accordingly, higher accessibility to enzymatic treatment. This property has been the basis of a number of sequencing-based assays for genome-wide identification and tracking the activity of CREs across different biological conditions, such as DNAse-seq, ATAC-seq , NOMeseq, and others. However, the fragmentation of DNA inherent to many of these assays and the limited read length of short-read sequencing platforms have so far not allowed the simultaneous measurement of the chromatin accessibility state of CREs located distally from each other. The combination of labeling accessible DNA with DNA modifications and nanopore sequencing has made it possible to develop such assays. Here, we provide a detailed protocol for carrying out the SMAC-seq assay (Single-Molecule long-read Accessible Chromatin mapping sequencing), in its m6A-SMAC-seq and m6A-CpG-GpC-SMAC-seq variants, together with methods for data processing and analysis, and discuss key experimental and analytical considerations for working with SMAC-seq datasets.
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Affiliation(s)
| | - Zohar Shipony
- Department of Genetics, Stanford University, Stanford, CA, USA.
| | - Anshul Kundaje
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University, Stanford, CA, USA
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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Li K, Carroll M, Vafabakhsh R, Wang XA, Wang JP. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3142-3154. [PMID: 35288750 PMCID: PMC8989542 DOI: 10.1093/nar/gkac162] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/16/2022] [Accepted: 02/23/2022] [Indexed: 11/16/2022] Open
Abstract
DNA mechanical properties play a critical role in every aspect of DNA-dependent biological processes. Recently a high throughput assay named loop-seq has been developed to quantify the intrinsic bendability of a massive number of DNA fragments simultaneously. Using the loop-seq data, we develop a software tool, DNAcycP, based on a deep-learning approach for intrinsic DNA cyclizability prediction. We demonstrate DNAcycP predicts intrinsic DNA cyclizability with high fidelity compared to the experimental data. Using an independent dataset from in vitro selection for enrichment of loopable sequences, we further verified the predicted cyclizability score, termed C-score, can well distinguish DNA fragments with different loopability. We applied DNAcycP to multiple species and compared the C-scores with available high-resolution chemical nucleosome maps. Our analyses showed that both yeast and mouse genomes share a conserved feature of high DNA bendability spanning nucleosome dyads. Additionally, we extended our analysis to transcription factor binding sites and surprisingly found that the cyclizability is substantially elevated at CTCF binding sites in the mouse genome. We further demonstrate this distinct mechanical property is conserved across mammalian species and is inherent to CTCF binding DNA motif.
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Affiliation(s)
- Keren Li
- Department of Statistics, Northwestern University, 633 Clark Street, Evanston, IL 60208, USA
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL 60208, USA
| | - Matthew Carroll
- Weinberg College IT Solutions (WITS), Northwestern University, 633 Clark Street, Evanston, IL 60208, USA
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Xiaozhong A Wang
- Correspondence may also be addressed to Xiaozhong A. Wang. Tel: +1 847 467 4897;
| | - Ji-Ping Wang
- To whom correspondence should be addressed. Tel: +1 847 467 6896;
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42
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Stark B, Poon GM, Wyrick JJ. Molecular mechanism of UV damage modulation in nucleosomes. Comput Struct Biotechnol J 2022; 20:5393-5400. [PMID: 36212527 PMCID: PMC9529667 DOI: 10.1016/j.csbj.2022.08.071] [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: 05/28/2022] [Revised: 08/31/2022] [Accepted: 08/31/2022] [Indexed: 12/02/2022] Open
Abstract
Exposure to ultraviolet (UV) light causes the formation of mutagenic cyclobutane pyrimidine dimers (CPDs) in cellular DNA. Previous studies have revealed that CPD formation in nucleosomes, the building blocks of chromatin, shows a striking ∼10 base pair (bp) periodic pattern. CPD formation is suppressed at positions where the DNA minor groove faces toward the histone octamer (minor-in) and elevated CPD formation at positions where the minor groove faces away from the histone octamer (minor-out). However, the molecular mechanism underlying this nucleosome photofootprint is unclear. Here, we analyzed ∼180 high-resolution nucleosome structures to characterize whether differences in DNA mobility or conformation are responsible for the CPD modulation in nucleosomes. Our results indicate that differences in DNA mobility cannot explain CPD modulation in nucleosome. Instead, we find that the sharp DNA bending around the histone octamer results in DNA conformations with structural parameters more susceptible to UV damage formation at minor-out positions and more resistant to CPD formation at minor-in positions. This analysis reveals the molecular mechanism responsible for periodic modulation of CPD formation and UV mutagenesis in nucleosomal DNA.
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43
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Mapping nucleosome and chromatin architectures: A survey of computational methods. Comput Struct Biotechnol J 2022; 20:3955-3962. [PMID: 35950186 PMCID: PMC9340519 DOI: 10.1016/j.csbj.2022.07.037] [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: 03/08/2022] [Revised: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 11/21/2022] Open
Abstract
With ever-growing genomic sequencing data, the data variabilities and the underlying biases of the sequencing technologies pose significant computational challenges ranging from the need for accurately detecting the nucleosome positioning or chromatin interaction to the need for developing normalization methods to eliminate systematic biases. This review mainly surveys the computational methods for mapping the higher-resolution nucleosome and higher-order chromatin architectures. While a detailed discussion of the underlying algorithms is beyond the scope of our survey, we have discussed the methods and tools that can detect the nucleosomes in the genome, then demonstrated the computational methods for identifying 3D chromatin domains and interactions. We further illustrated computational approaches for integrating multi-omics data with Hi-C data and the advance of single-cell (sc)Hi-C data analysis. Our survey provides a comprehensive and valuable resource for biomedical scientists interested in studying nucleosome organization and chromatin structures as well as for computational scientists who are interested in improving upon them.
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44
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Reb1, Cbf1, and Pho4 bias histone sliding and deposition away from their binding sites. Mol Cell Biol 2021; 42:e0047221. [PMID: 34898278 DOI: 10.1128/mcb.00472-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In transcriptionally active genes, nucleosome positions in promoters are regulated by nucleosome displacing factors (NDFs) and chromatin remodeling enzymes. Depletion of NDFs or the RSC chromatin remodeler shrinks or abolishes the nucleosome depleted regions (NDRs) in promoters, which can suppress gene activation and result in cryptic transcription. Despite their vital cellular functions, how the action of chromatin remodelers may be directly affected by site-specific binding factors like NDFs is poorly understood. Here we demonstrate that two NDFs, Reb1 and Cbf1, can direct both Chd1 and RSC chromatin remodeling enzymes in vitro, stimulating repositioning of the histone core away from their binding sites. Interestingly, although the Pho4 transcription factor had a much weaker effect on nucleosome positioning, both NDFs and Pho4 were able to similarly redirect positioning of hexasomes. In chaperone-mediated nucleosome assembly assays, Reb1 but not Pho4 showed an ability to block deposition of the histone H3/H4 tetramer, but Reb1 did not block addition of the H2A/H2B dimer to hexasomes. Our in vitro results show that NDFs bias the action of remodelers to increase the length of the free DNA in the vicinity of their binding sites. These results suggest that NDFs could directly affect NDR architecture through chromatin remodelers.
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45
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Kim M, Bae S, Oh I, Yoo J, Kim JS. Sequence-dependent twist-bend coupling in DNA minicircles. NANOSCALE 2021; 13:20186-20196. [PMID: 34847218 DOI: 10.1039/d1nr04672a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Looping of double-stranded DNA molecules with 100-200 base pairs into minicircles, catenanes, and rotaxanes has been suggested as a potential tool for DNA nanotechnologies. However, sharp DNA bending into a minicircle with a diameter of several to ten nanometers occurs with alterations in the DNA helical structure and may lead to defective kink formation that hampers the use of DNA minicircles, catenanes, and rotaxanes in nanoscale DNA applications. Here, we investigated local variations of a helical twist in sharply bent DNA using microsecond-long all-atom molecular dynamics simulations of six different DNA minicircles, focusing on the sequence dependence of the coupling between DNA bending and its helical twist. Twist angles between consecutive base pairs were analyzed at different locations relative to the direction of DNA bending and, among 10 unique dinucleotide steps, we identified four dinucleotide steps with strong twist-bend coupling, the pyrimidine-purine dinucleotide steps of TA/TA, CG/CG, and CA/TG and the purine-purine dinucleotide step of GA/TC. This work suggests the sequence-dependent structural responses of DNA to strong mechanical deformation, providing new molecular-level insights into the structure and stability of sharply bent DNA minicircles for nanoscale applications.
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Affiliation(s)
- Minjung Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Sehui Bae
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Inrok Oh
- LG Chem Ltd, LG Science Park, Seoul 07796, Republic of Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jun Soo Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
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46
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Xu B, Li X, Gao X, Jia Y, Liu J, Li F, Zhang Z. DeNOPA: decoding nucleosome positions sensitively with sparse ATAC-seq data. Brief Bioinform 2021; 23:6454261. [PMID: 34875002 DOI: 10.1093/bib/bbab469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/09/2021] [Accepted: 10/13/2021] [Indexed: 12/25/2022] Open
Abstract
As the basal bricks, the dynamics and arrangement of nucleosomes orchestrate the higher architecture of chromatin in a fundamental way, thereby affecting almost all nuclear biology processes. Thanks to its rather simple protocol, assay for transposase-accessible chromatin using sequencing (ATAC)-seq has been rapidly adopted as a major tool for chromatin-accessible profiling at both bulk and single-cell levels; however, to picture the arrangement of nucleosomes per se remains a challenge with ATAC-seq. In the present work, we introduce a novel ATAC-seq analysis toolkit, named decoding nucleosome organization profile based on ATAC-seq data (deNOPA), to predict nucleosome positions. Assessments showed that deNOPA outperformed state-of-the-art tools with ultra-sparse ATAC-seq data, e.g. no more than 0.5 fragment per base pair. The remarkable performance of deNOPA was fueled by the short fragment reads, which compose nearly half of sequenced reads in the ATAC-seq libraries and are commonly discarded by state-of-the-art nucleosome positioning tools. However, we found that the short fragment reads enrich information on nucleosome positions and that the linker regions were predicted by reads from both short and long fragments using Gaussian smoothing. Last, using deNOPA, we showed that the dynamics of nucleosome organization may not directly couple with chromatin accessibility in the cis-regulatory regions when human cells respond to heat shock stimulation. Our deNOPA provides a powerful tool with which to analyze the dynamics of chromatin at nucleosome position level with ultra-sparse ATAC-seq data.
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Affiliation(s)
- Bingxiang Xu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, P.R. China.,School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Xiaoli Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Xiaomeng Gao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Yan Jia
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China
| | - Jing Liu
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Feifei Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China
| | - Zhihua Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, and China National Center for Bioinformation, Beijing 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, P.R. China.,School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, P.R. China
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47
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Jacobs RQ, Huffines AK, Laiho M, Schneider DA. The small-molecule BMH-21 directly inhibits transcription elongation and DNA occupancy of RNA polymerase I in vivo and in vitro. J Biol Chem 2021; 298:101450. [PMID: 34838819 PMCID: PMC8683726 DOI: 10.1016/j.jbc.2021.101450] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022] Open
Abstract
Cancer cells are dependent upon an abundance of ribosomes to maintain rapid cell growth and proliferation. The rate-limiting step of ribosome biogenesis is ribosomal RNA (rRNA) synthesis by RNA polymerase I (Pol I). Therefore, a goal of the cancer therapeutic field is to develop and characterize Pol I inhibitors. Here, we elucidate the mechanism of Pol I inhibition by a first-in-class small-molecule BMH-21. To characterize the effects of BMH-21 on Pol I transcription, we leveraged high-resolution in vitro transcription assays and in vivo native elongating transcript sequencing (NET-seq). We find that Pol I transcription initiation, promoter escape, and elongation are all inhibited by BMH-21 in vitro. In particular, the transcription elongation phase is highly sensitive to BMH-21 treatment, as it causes a decrease in transcription elongation rate and an increase in paused Pols on the ribosomal DNA (rDNA) template. In vivo NET-seq experiments complement these findings by revealing a reduction in Pol I occupancy on the template and an increase in sequence-specific pausing upstream of G-rich rDNA sequences after BMH-21 treatment. Collectively, these data reveal the mechanism of action of BMH-21, which is a critical step forward in the development of this compound and its derivatives for clinical use.
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Affiliation(s)
- Ruth Q Jacobs
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Abigail K Huffines
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Marikki Laiho
- Department of Radiation Oncology and Molecular Radiation Sciences and Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - David A Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA.
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48
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Bae S, Kim JS. Potential of Mean Force for DNA Wrapping Around a Cationic Nanoparticle. J Chem Theory Comput 2021; 17:7952-7961. [PMID: 34792353 DOI: 10.1021/acs.jctc.1c00797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Sharp bending and wrapping of DNA around proteins and nanoparticles (NPs) has been of extensive research interest. Here, we present the potential of mean force (PMF) for wrapping a DNA double helix around a cationic NP using coarse-grained models of a double-stranded DNA and a cationic NP. Starting from a NP wrapped around by DNA, the PMF was calculated along the distance between the center of the NP and one end of the DNA molecule. A relationship between the distance and the extent of DNA wrapping is used to calculate the PMF as a function of DNA wrapping around a NP. In particular, the PMF was compared for two DNA sequences of (AT)25/(AT)25 and (AC)25/(GT)25, for which the persistence lengths are different by ∼10 nm. The simulation results provide solid evidence of the thermodynamic preference for complex formation of a cationic NP with more flexible DNA over the less flexible DNA. Furthermore, we estimated the elastic energy of DNA bending, which was in good order-of-magnitude agreement with the theoretical prediction of elastic rods. This work suggests that the variation of sequence-dependent DNA flexibility can be utilized in DNA nanotechnologies, in which the position and dynamics of NPs are regulated on large-scale DNA structures, or the structural transformation of DNA is triggered by the sequence-dependent binding of NPs.
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Affiliation(s)
- Sehui Bae
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jun Soo Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
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49
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Yoo J, Park S, Maffeo C, Ha T, Aksimentiev A. DNA sequence and methylation prescribe the inside-out conformational dynamics and bending energetics of DNA minicircles. Nucleic Acids Res 2021; 49:11459-11475. [PMID: 34718725 PMCID: PMC8599915 DOI: 10.1093/nar/gkab967] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 09/27/2021] [Accepted: 10/11/2021] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic genome and methylome encode DNA fragments' propensity to form nucleosome particles. Although the mechanical properties of DNA possibly orchestrate such encoding, the definite link between 'omics' and DNA energetics has remained elusive. Here, we bridge the divide by examining the sequence-dependent energetics of highly bent DNA. Molecular dynamics simulations of 42 intact DNA minicircles reveal that each DNA minicircle undergoes inside-out conformational transitions with the most likely configuration uniquely prescribed by the nucleotide sequence and methylation of DNA. The minicircles' local geometry consists of straight segments connected by sharp bends compressing the DNA's inward-facing major groove. Such an uneven distribution of the bending stress favors minimum free energy configurations that avoid stiff base pair sequences at inward-facing major grooves. Analysis of the minicircles' inside-out free energy landscapes yields a discrete worm-like chain model of bent DNA energetics that accurately account for its nucleotide sequence and methylation. Experimentally measuring the dependence of the DNA looping time on the DNA sequence validates the model. When applied to a nucleosome-like DNA configuration, the model quantitatively reproduces yeast and human genomes' nucleosome occupancy. Further analyses of the genome-wide chromatin structure data suggest that DNA bending energetics is a fundamental determinant of genome architecture.
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Affiliation(s)
- Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Sangwoo Park
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Christopher Maffeo
- Department of Physics and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
- Howard Hughes Medical Institute, Baltimore, MD 21218, USA
| | - Aleksei Aksimentiev
- Department of Physics and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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50
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Abstract
Transcription factors (TFs) are essential mediators of epigenetic regulation and modifiers of penetrance. Studies from the past decades have revealed a sub-class of TF that is capable of remodeling closed chromatin states through targeting nucleosomal motifs. This pioneer factor (PF) class of chromatin remodeler is ATP independent in its roles in epigenetic initiation, with nucleosome-motif recognition and association with repressive chromatin regions. Increasing evidence suggests that the fundamental properties of PFs can be coopted in human cancers. We explore the role of PFs in the larger context of tissue-specific epigenetic regulation. Moreover, we highlight an emerging class of chimeric PF derived from translocation partners in human disease and PFs associated with rare tumors. In the age of site-directed genome editing and targeted protein degradation, increasing our understanding of PFs will provide access to next-generation therapy for human disease driven from altered transcriptional circuitry.
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