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Patel R, Loverde SM. Unveiling the Conformational Dynamics of the Histone Tails Using Markov State Modeling. J Chem Theory Comput 2025; 21:4921-4938. [PMID: 40289377 PMCID: PMC12080106 DOI: 10.1021/acs.jctc.5c00196] [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: 02/03/2025] [Revised: 04/21/2025] [Accepted: 04/22/2025] [Indexed: 04/30/2025]
Abstract
Biomolecules predominantly exert their function by altering conformational dynamics. The nucleosome core particle (NCP) is the fundamental unit of chromatin. DNA with ∼146 base pairs wraps around the histone octamer to form a nucleosome. The histone octamer is composed of two copies of each histone protein (H3, H4, H2A, and H2B) with a globular core and disordered N-terminal tails. Epigenetic modifications of the histone N-terminal tails play a critical role in regulating the chromatin structure and biological processes such as transcription and DNA repair. Here, we report all-atom molecular dynamics (MD) simulations of the nucleosome at microsecond time scales to construct Markov state models (MSMs) to elucidate distinct conformations of the histone tails. We employ time-lagged independent component analysis (tICA) to capture their essential slow dynamics, with k-means clustering used to discretize the conformational space. MSMs unveil distinct states and transition probabilities to characterize the dynamics and kinetics of the tails. Next, we focus on the H2B tail, which is one of the least studied tails. We show that acetylation increases secondary structure formation with increased transition rates. These findings will aid in understanding the functional implications of tail conformations for nucleosome stability and gene regulation.
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Affiliation(s)
- Rutika Patel
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, United States
| | - Sharon M. Loverde
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, United States
- Ph.D.
Program in Chemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Ph.D.
Program in Physics, The Graduate Center
of the City University of New York, New York, New York 10016, United States
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2
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Patel R, Loverde SM. Unveiling the Conformational Dynamics of the Histone Tails Using Markov State Modeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.01.16.633411. [PMID: 39896498 PMCID: PMC11785091 DOI: 10.1101/2025.01.16.633411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/04/2025]
Abstract
Biomolecules predominantly exert their function through altering conformational dynamics. The nucleosome core particle (NCP) is the fundamental unit of chromatin. DNA with ~146 base pairs wrap around the histone octamer to form a nucleosome. The histone octamer is comprised of two copies of each histone protein (H3, H4, H2A, and H2B) with a globular core and disordered N-terminal tails. Epigenetic modifications of the histone N-terminal tails play a critical role in the regulation of chromatin structure and biological processes such as transcription and DNA repair. Here, we report all-atomistic molecular dynamics (MD) simulations of the nucleosome at microsecond timescales to construct Markov state models (MSMs) to elucidate distinct conformations of the histone tails. We employ the time-lagged independent component analysis (tICA) to capture their essential slow dynamics, with k-means clustering used to discretize the conformational space. MSMs unveil distinct states and transition probabilities to characterize the dynamics and kinetics of the tails. Next, we focus on the H2B tail, one of the least studied tails. We show that acetylation increases secondary structure formation, with an increase in transition rates. These findings will aid in understanding the functional implications of tail conformations in nucleosome stability and gene regulation.
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Affiliation(s)
- Rutika Patel
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016
- Department of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York, 10314, United States
| | - Sharon M. Loverde
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016
- Department of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York, 10314, United States
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016
- Ph.D. Program in Physics, The Graduate Center of the City University of New York, New York, NY, 10016
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3
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Patel R, Onyema A, Tang PK, Loverde SM. Conformational Dynamics of the Nucleosomal Histone H2B Tails Revealed by Molecular Dynamics Simulations. J Chem Inf Model 2024; 64:4709-4726. [PMID: 38865599 PMCID: PMC11200259 DOI: 10.1021/acs.jcim.4c00059] [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: 01/11/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/14/2024]
Abstract
Epigenetic modifications of histone N-terminal tails play a critical role in regulating the chromatin structure and biological processes such as transcription and DNA repair. One of the key post-translational modifications (PTMs) is the acetylation of lysine residues on histone tails. Epigenetic modifications are ubiquitous in the development of diseases, such as cancer and neurological disorders. Histone H2B tails are critical regulators of nucleosome dynamics, biological processes, and certain diseases. Here, we report all-atomistic molecular dynamics (MD) simulations of the nucleosome to demonstrate that acetylation of the histone tails changes their conformational space and interaction with DNA. We perform simulations of H2B tails, critical regulators of gene regulation, in both the lysine-acetylated (ACK) and unacetylated wild type (WT) states. To explore the effects of salt concentration, we use two different NaCl concentrations to perform simulations at microsecond time scales. Salt can modulate the effects of electrostatic interactions between the DNA phosphate backbone and histone tails. Upon acetylation, H2B tails shift their secondary structure helical propensity. The number of contacts between the DNA and the H2B tail decreases. We characterize the conformational dynamics of the H2B tails by principal component analysis (PCA). The ACK tails become more compact at increased salt concentrations, but conformations from the WT tails display the most contacts with DNA at both salt concentrations. Mainly, H2B acetylation may increase the DNA accessibility for regulatory proteins to bind, which can aid in gene regulation and NCP stability.
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Affiliation(s)
- Rutika Patel
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New
York, New York 10314, United States
| | - Augustine Onyema
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New
York, New York 10314, United States
| | - Phu K. Tang
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New
York, New York 10314, United States
| | - Sharon M. Loverde
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New
York, New York 10314, United States
- Ph.D.
Program in Chemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Ph.D.
Program in Physics, The Graduate Center
of the City University of New York, New York, New York 10016, United States
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4
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Gillet N, Dumont E, Bignon E. DNA damage and repair in the nucleosome: insights from computational methods. Biophys Rev 2024; 16:345-356. [PMID: 39099841 PMCID: PMC11297232 DOI: 10.1007/s12551-024-01183-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 03/05/2024] [Indexed: 08/06/2024] Open
Abstract
Cellular DNA is constantly exposed to endogenous or exogenous factors that can induce lesions. Several types of lesions have been described that can result from UV/ionizing irradiations, oxidative stress, or free radicals, among others. In order to overcome the deleterious effects of such damages, i.e., mutagenicity or cytotoxicity, cells possess a highly complex DNA repair machinery, involving repair enzymes targeting specific types of lesions through dedicated cellular pathways. In addition, DNA is highly compacted in the nucleus, the first level of compaction consisting of ~ 147 DNA base pairs wrapped around a core of histones, the so-called nucleosome core particle. In this complex environment, the DNA structure is highly constrained, and fine-tuned mechanisms involving remodeling processes are required to expose the DNA to repair enzymes and to facilitate the damage removal. However, these nucleosome-specific mechanisms remain poorly understood, and computational methods emerged only recently as powerful tools to investigate DNA damages in such complex systems as the nucleosome. In this mini-review, we summarize the latest advances brought out by computational approaches in the field, opening new exciting perspectives for the study of DNA damage and repair in the nucleosome context.
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Affiliation(s)
- Natacha Gillet
- ENS de Lyon, CNRS, Université Claude Bernard Lyon 1, Laboratoire de Chimie UMR 5182, 69342 Lyon, France
| | - Elise Dumont
- Institut de Chimie de Nice, UMR 7272, Université Côte d’Azur, CNRS, 06108 Nice, France
- Institut Universitaire de France, 5 Rue Descartes, 75005 Paris, France
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5
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Wang H, Liu B, Chen H, Xu P, Xue H, Yuan J. Dynamic changes of DNA methylation induced by benzo(a)pyrene in cancer. Genes Environ 2023; 45:21. [PMID: 37391844 DOI: 10.1186/s41021-023-00278-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/07/2023] [Indexed: 07/02/2023] Open
Abstract
Benzo(a)pyrene (BaP), the earliest and most significant carcinogen among polycyclic aromatic hydrocarbons (PAHs), has been found in foods, tobacco smoke, and automobiles exhaust, etc. Exposure to BaP induced DNA damage directly, or oxidative stress-related damage, resulting in cell apoptosis and carcinogenesis in human respiratory system, digestive system, reproductive system, etc. Moreover, BaP triggered genome-wide epigenetic alterations by methylation, which might cause disturbances in regulation of gene expression, and thereby induced cancer. It has been proved that BaP reduced genome-wide DNA methylation, and activated proto-oncogene by hypomethylation in the promoter region, but silenced tumor suppressor genes by promoter hypermethylation, resulting in cancer initiation and progression. Here we summarized the changes in DNA methylation in BaP exposure, and revealed the methylation of DNA plays a role in cancer development.
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Affiliation(s)
- Huizeng Wang
- Department of Laboratory Medicine, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, 010050, China
| | - Bingchun Liu
- Stem Cell Research Center, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, 010050, China
| | - Hong Chen
- Department of Laboratory Medicine, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, 010050, China
| | - Peixin Xu
- Department of Laboratory Medicine, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, 010050, China
| | - Huiting Xue
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, 010010, China.
| | - Jianlong Yuan
- Department of Laboratory Medicine, the Affiliated Hospital of Inner Mongolia Medical University, Hohhot, 010050, China.
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6
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Rioux KL, Delaney S. Ionic strength modulates excision of uracil by SMUG1 from nucleosome core particles. DNA Repair (Amst) 2023; 125:103482. [PMID: 36931160 PMCID: PMC10073303 DOI: 10.1016/j.dnarep.2023.103482] [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: 12/20/2022] [Revised: 03/04/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023]
Abstract
Ionic strength affects many cellular processes including the packaging of genetic material in eukaryotes. For example, chromatin fibers are compacted in high ionic strength environments as are the minimal unit of packaging in chromatin, nucleosome core particles (NCPs). Furthermore, ionic strength is known to modulate several aspects of NCP dynamics including transient unwrapping of DNA from the histone protein core, nucleosome gaping, and intra- and internucleosomal interactions of the N-terminal histone tails. Changes in NCP structure may also impact interactions of transcriptional, repair, and other cellular machinery with nucleosomal DNA. One repair process, base excision repair (BER), is impacted by NCP structure and may be further influenced by changes in ionic strength. Here we examine the effects of ionic strength on the initiation of BER using biochemical assays. Using a population of NCPs containing uracil (U) at dozens of geometric locations, excision of U by single-strand selective monofunctional uracil DNA glycosylase (SMUG1) is assessed at higher and lower ionic strengths. SMUG1 has increased excision activity in the lower ionic strength conditions. On duplex DNA, however, SMUG1 activity is largely unaffected by ionic strength except at short incubation times, suggesting that changes in SMUG1 activity are likely due to alterations in NCP structure and dynamics. These results allow us to further understand the cellular role of SMUG1 in a changing ionic environment and broadly contribute to the understanding of BER on chromatin and genomic stability.
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Affiliation(s)
- Katelyn L Rioux
- Department of Chemistry, Brown University, Providence, RI, USA
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, RI, USA.
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7
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Histone variants H3.3 and H2A.Z/H3.3 facilitate excision of uracil from nucleosome core particles. DNA Repair (Amst) 2022; 116:103355. [PMID: 35717761 PMCID: PMC9262417 DOI: 10.1016/j.dnarep.2022.103355] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/31/2022] [Accepted: 06/08/2022] [Indexed: 11/20/2022]
Abstract
At the most fundamental level of chromatin organization, DNA is packaged as nucleosome core particles (NCPs) where DNA is wound around a core of histone proteins. This ubiquitous sequestration of DNA within NCPs presents a significant barrier to many biological processes, including DNA repair. We previously demonstrated that histone variants from the H2A family facilitate excision of uracil (U) lesions by DNA base excision repair (BER) glycosylases. Here, we consider how the histone variant H3.3 and double-variant H2A.Z/H3.3 modulate the BER enzymes uracil DNA glycosylase (UDG) and single-strand selective monofunctional uracil DNA glycosylase (SMUG1). Using an NCP model system with U:G base pairs at a wide variety of geometric positions we generate the global repair profile for both glycosylases. Enhanced excision of U by UDG and SMUG1 is observed with the H3.3 variant. We demonstrate that these H3.3-containing NCPs form two species: (1) octasomes, which contain the full complement of eight histone proteins and (2) hexasomes which are sub-nucleosomal particles that contain six histones. Both the octasome and hexasome species facilitate excision activity of UDG and SMUG1, with the largest impacts observed at sterically-occluded lesion sites and in terminal regions of DNA of the hexasome that do not closely interact with histones. For the double-variant H2A.Z/H3.3 NCPs, which exist as octasomes, the global repair profile reveals that UDG but not SMUG1 has increased U excision activity. The enhanced glycosylase activity reveals potential functions for these histone variants to facilitate BER in packaged DNA and contributes to our understanding of DNA repair in chromatin and its significance regarding mutagenesis and genomic integrity.
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8
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Bignon E, Gillet N, Jiang T, Morell C, Dumont E. A Dynamic View of the Interaction of Histone Tails with Clustered Abasic Sites in a Nucleosome Core Particle. J Phys Chem Lett 2021; 12:6014-6019. [PMID: 34165307 DOI: 10.1021/acs.jpclett.1c01058] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Apurinic/apyrimidinic sites are the most common forms of DNA damage under physiological conditions, yet their structural and dynamical behavior within nucleosome core particles has just begun to be investigated and is dramatically different from that of abasic sites in B-DNA. Clusters of two or more abasic sites are repaired even less efficiently and hence constitute hot spots of high mutagenicity notably due to enhanced double-strand break formation. On the basis of an X-ray structure of a 146 bp DNA wrapped onto a histone core, we investigate the structural behavior of two bistranded abasic sites positioned at mutational hot spots during microsecond-range molecular dynamics simulations. Our simulations allow us to probe interactions of histone tails at clustered abasic site locations, with a definitive assignment of the key residues involved in the NCP-catalyzed formation of DNA-protein cross-linking in line with recent experimental findings, and pave the way for a systematic assessment of the response of histone tails to DNA lesions.
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Affiliation(s)
- Emmanuelle Bignon
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Laboratoire de Chimie, F69342 Lyon, France
- Université de Lyon, Institut des Sciences Analytiques, UMR 5280 CNRS, Université Claude Bernard Lyon 1, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Natacha Gillet
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Laboratoire de Chimie, F69342 Lyon, France
| | - Tao Jiang
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Laboratoire de Chimie, F69342 Lyon, France
| | - Christophe Morell
- Université de Lyon, Institut des Sciences Analytiques, UMR 5280 CNRS, Université Claude Bernard Lyon 1, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Elise Dumont
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Laboratoire de Chimie, F69342 Lyon, France
- Institut Universitaire de France, 5 rue Descartes, 75005 Paris, France
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9
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Ohtomo H, Kurita JI, Sakuraba S, Li Z, Arimura Y, Wakamori M, Tsunaka Y, Umehara T, Kurumizaka H, Kono H, Nishimura Y. The N-terminal Tails of Histones H2A and H2B Adopt Two Distinct Conformations in the Nucleosome with Contact and Reduced Contact to DNA. J Mol Biol 2021; 433:167110. [PMID: 34153285 DOI: 10.1016/j.jmb.2021.167110] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 11/28/2022]
Abstract
The nucleosome comprises two histone dimers of H2A-H2B and one histone tetramer of (H3-H4)2, wrapped around by ~145 bp of DNA. Detailed core structures of nucleosomes have been established by X-ray and cryo-EM, however, histone tails have not been visualized. Here, we have examined the dynamic structures of the H2A and H2B tails in 145-bp and 193-bp nucleosomes using NMR, and have compared them with those of the H2A and H2B tail peptides unbound and bound to DNA. Whereas the H2A C-tail adopts a single but different conformation in both nucleosomes, the N-tails of H2A and H2B adopt two distinct conformations in each nucleosome. To clarify these conformations, we conducted molecular dynamics (MD) simulations, which suggest that the H2A N-tail can locate stably in either the major or minor grooves of nucleosomal DNA. While the H2B N-tail, which sticks out between two DNA gyres in the nucleosome, was considered to adopt two different orientations, one toward the entry/exit side and one on the opposite side. Then, the H2A N-tail minor groove conformation was obtained in the H2B opposite side and the H2B N-tail interacts with DNA similarly in both sides, though more varied conformations are obtained in the entry/exit side. Collectively, the NMR findings and MD simulations suggest that the minor groove conformer of the H2A N-tail is likely to contact DNA more strongly than the major groove conformer, and the H2A N-tail reduces contact with DNA in the major groove when the H2B N-tail is located in the entry/exit side.
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Affiliation(s)
- Hideaki Ohtomo
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Jun-Ichi Kurita
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Shun Sakuraba
- Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology (QST), 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Zhenhai Li
- Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology (QST), 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Yasuhiro Arimura
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Masatoshi Wakamori
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research (BDR), 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Yasuo Tsunaka
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Takashi Umehara
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research (BDR), 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hidetoshi Kono
- Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology (QST), 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
| | - Yoshifumi Nishimura
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan; Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8258, Japan.
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10
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Ghoneim M, Fuchs HA, Musselman CA. Histone Tail Conformations: A Fuzzy Affair with DNA. Trends Biochem Sci 2021; 46:564-578. [PMID: 33551235 DOI: 10.1016/j.tibs.2020.12.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 12/13/2022]
Abstract
The core histone tails are critical in chromatin structure and signaling. Studies over the past several decades have provided a wealth of information on the histone tails and their interaction with chromatin factors. However, the conformation of the histone tails in a chromatin relevant context has remained elusive. Only recently has enough evidence emerged to start to build a structural model of the tails in the context of nucleosomes and nucleosome arrays. Here, we review these studies and propose that the histone tails adopt a high-affinity fuzzy complex with DNA, characterized by robust but dynamic association. Furthermore, we discuss how these DNA-bound conformational ensembles promote distinct chromatin structure and signaling, and that their fuzzy nature is important in transitioning between functional states.
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Affiliation(s)
- Mohamed Ghoneim
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Harrison A Fuchs
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Catherine A Musselman
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
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11
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Caffrey PJ, Delaney S. Nucleosome Core Particles Lacking H2B or H3 Tails Are Altered Structurally and Have Differential Base Excision Repair Fingerprints. Biochemistry 2021; 60:210-218. [PMID: 33426868 DOI: 10.1021/acs.biochem.0c00877] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A recently discovered post-translational modification of histone proteins is the irreversible proteolytic clipping of the histone N-terminal tail domains. This modification is involved in the regulation of various biological processes, including the DNA damage response. In this work, we used chemical footprinting to characterize the structural alterations to nucleosome core particles (NCPs) that result from a lack of a histone H2B or H3 tail. We also examine the influence of these histone tails on excision of the mutagenic lesion 1,N6-ethenoadenine (εA) by the repair enzyme alkyladenine DNA glycosylase. We found that the absence of the H2B or H3 tail results in altered DNA periodicity relative to that of native NCPs. We correlated these structural alterations to εA excision by utilizing a global analysis of 21 εA sites in NCPs and unincorporated duplex DNA. In comparison to native NCPs, there is enhanced excision of εA in tailless H2B NCPs in regions that undergo DNA unwrapping. This enhanced excision is not observed for tailless H3 NCPs; rather, excision is inhibited in more static areas of the NCP not prone to unwrapping. Our results support in vivo observations of alkylation damage profiles and the potential role of tail clipping as a mechanism for overcoming physical obstructions caused by packaging in NCPs but also reveal the potential inhibition of repair by tail clipping in some locations. Taken together, these results further our understanding of how base excision repair can be facilitated or diminished by histone tail removal and contribute to our understanding of the underlying mechanism that leads to mutational hot spots.
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Affiliation(s)
- Paul J Caffrey
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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12
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Huertas J, Cojocaru V. Breaths, Twists, and Turns of Atomistic Nucleosomes. J Mol Biol 2020; 433:166744. [PMID: 33309853 DOI: 10.1016/j.jmb.2020.166744] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/02/2020] [Accepted: 12/02/2020] [Indexed: 02/07/2023]
Abstract
Gene regulation programs establish cellular identity and rely on dynamic changes in the structural packaging of genomic DNA. The DNA is packaged in chromatin, which is formed from arrays of nucleosomes displaying different degree of compaction and different lengths of inter-nucleosomal linker DNA. The nucleosome represents the repetitive unit of chromatin and is formed by wrapping 145-147 basepairs of DNA around an octamer of histone proteins. Each of the four histones is present twice and has a structured core and intrinsically disordered terminal tails. Chromatin dynamics are triggered by inter- and intra-nucleosome motions that are controlled by the DNA sequence, the interactions between the histone core and the DNA, and the conformations, positions, and DNA interactions of the histone tails. Understanding chromatin dynamics requires studying all these features at the highest possible resolution. For this, molecular dynamics simulations can be used as a powerful complement or alternative to experimental approaches, from which it is often very challenging to characterize the structural features and atomic interactions controlling nucleosome motions. Molecular dynamics simulations can be performed at different resolutions, by coarse graining the molecular system with varying levels of details. Here we review the successes and the remaining challenges of the application of atomic resolution simulations to study the structure and dynamics of nucleosomes and their complexes with interacting partners.
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Affiliation(s)
- Jan Huertas
- In Silico Biomolecular Structure and Dynamics Group, Hubrecht Institute, Utrecht, the Netherlands; Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany
| | - Vlad Cojocaru
- In Silico Biomolecular Structure and Dynamics Group, Hubrecht Institute, Utrecht, the Netherlands; Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany.
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13
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Bignon E, Claerbout VEP, Jiang T, Morell C, Gillet N, Dumont E. Nucleosomal embedding reshapes the dynamics of abasic sites. Sci Rep 2020; 10:17314. [PMID: 33057206 PMCID: PMC7560594 DOI: 10.1038/s41598-020-73997-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/31/2020] [Indexed: 12/16/2022] Open
Abstract
Apurinic/apyrimidinic (AP) sites are the most common DNA lesions, which benefit from a most efficient repair by the base excision pathway. The impact of losing a nucleobase on the conformation and dynamics of B-DNA is well characterized. Yet AP sites seem to present an entirely different chemistry in nucleosomal DNA, with lifetimes reduced up to 100-fold, and the much increased formation of covalent DNA-protein cross-links leading to strand breaks, refractory to repair. We report microsecond range, all-atom molecular dynamics simulations that capture the conformational dynamics of AP sites and their tetrahydrofuran analogs at two symmetrical positions within a nucleosome core particle, starting from a recent crystal structure. Different behaviours between the deoxyribo-based and tetrahydrofuran-type abasic sites are evidenced. The two solvent-exposed lesion sites present contrasted extrahelicities, revealing the crucial role of the position of a defect around the histone core. Our all-atom simulations also identify and quantify the frequency of several spontaneous, non-covalent interactions between AP and positively-charged residues from the histones H2A and H2B tails that prefigure DNA-protein cross-links. Such an in silico mapping of DNA-protein cross-links gives important insights for further experimental studies involving mutagenesis and truncation of histone tails to unravel mechanisms of DPCs formation.
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Affiliation(s)
- Emmanuelle Bignon
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France. .,Institut des Sciences Analytiques, UMR 5280, Université de Lyon 1 (UCBL) CNRS, Lyon, France.
| | - Victor E P Claerbout
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - Tao Jiang
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - Christophe Morell
- Institut des Sciences Analytiques, UMR 5280, Université de Lyon 1 (UCBL) CNRS, Lyon, France
| | - Natacha Gillet
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - Elise Dumont
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France. .,Institut Universitaire de France, 5 rue Descartes, 75005, Paris, France.
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14
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Yoo J, Winogradoff D, Aksimentiev A. Molecular dynamics simulations of DNA-DNA and DNA-protein interactions. Curr Opin Struct Biol 2020; 64:88-96. [PMID: 32682257 DOI: 10.1016/j.sbi.2020.06.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/03/2020] [Accepted: 06/08/2020] [Indexed: 12/12/2022]
Abstract
The all-atom molecular dynamics method can characterize the molecular-level interactions in DNA and DNA-protein systems with unprecedented resolution. Recent advances in computational technologies have allowed the method to reveal the unbiased behavior of such systems at the microseconds time scale, whereas enhanced sampling approaches have matured enough to characterize the interaction free energy with quantitative precision. Here, we describe recent progress toward increasing the realism of such simulations by refining the accuracy of the molecular dynamics force field, and we highlight recent application of the method to systems of outstanding biological interest.
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Affiliation(s)
- Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea; Center for Self-assembly and Complexity, Institute for Basic Science, Pohang 37673, Republic of Korea.
| | - David Winogradoff
- Department of Physics and the Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, 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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15
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Caffrey PJ, Kher R, Bian K, Li D, Delaney S. Comparison of the Base Excision and Direct Reversal Repair Pathways for Correcting 1, N6-Ethenoadenine in Strongly Positioned Nucleosome Core Particles. Chem Res Toxicol 2020; 33:1888-1896. [PMID: 32293880 PMCID: PMC7374743 DOI: 10.1021/acs.chemrestox.0c00089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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1,N6-ethenoadenine (εA) is a
mutagenic lesion and biomarker observed in numerous cancerous tissues.
Two pathways are responsible for its repair: base excision repair
(BER) and direct reversal repair (DRR). Alkyladenine DNA glycosylase
(AAG) is the primary enzyme that excises εA in BER, generating
stable intermediates that are processed by downstream enzymes. For
DRR, the Fe(II)/α-ketoglutarate-dependent ALKBH2 enzyme repairs
εA by direct conversion of εA to A. While the molecular
mechanism of each enzyme is well understood on unpackaged duplex DNA,
less is known about their actions on packaged DNA. The nucleosome
core particle (NCP) forms the minimal packaging unit of DNA in eukaryotic
organisms and is composed of 145–147 base pairs wrapped around
a core of eight histone proteins. In this work, we investigated the
activity of AAG and ALKBH2 on εA lesions globally distributed
at positions throughout a strongly positioned NCP. Overall, we examined
the repair of εA at 23 unique locations in packaged DNA. We
observed a strong correlation between rotational positioning of εA
and AAG activity but not ALKBH2 activity. ALKBH2 was more effective
than AAG at repairing occluded εA lesions, but only AAG was
capable of full repair of any εA in the NCP. However, notable
exceptions to these trends were observed, highlighting the complexity
of the NCP as a substrate for DNA repair. Modeling of binding of the
repair enzymes to NCPs revealed that some of these observations can
be explained by steric interference caused by DNA packaging. Specifically,
interactions between ALKBH2 and the histone proteins obstruct binding
to DNA, which leads to diminished activity. Taken together, these
results support in vivo observations of alkylation
damage profiles and contribute to our understanding of mutational
hotspots.
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Affiliation(s)
- Paul J Caffrey
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Raadhika Kher
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Ke Bian
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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16
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Cai Y, Geacintov NE, Broyde S. Variable impact of conformationally distinct DNA lesions on nucleosome structure and dynamics: Implications for nucleotide excision repair. DNA Repair (Amst) 2019; 87:102768. [PMID: 32018112 DOI: 10.1016/j.dnarep.2019.102768] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/14/2019] [Accepted: 12/08/2019] [Indexed: 12/26/2022]
Abstract
The packaging of DNA in nucleosomes presents a barrier for biological transactions including replication, transcription and repair. However, despite years of research, how the DNA is freed from the histone proteins and thereby allows the molecular machines to access the DNA remains poorly understood. We are interested in global genomic nucleotide excision repair (GG-NER). It is established that the histones are obstacles to this process, and DNA lesions are repaired less efficiently in nucleosomes than in free DNA. In the present study, we utilized molecular dynamics simulations to elucidate the nature of the distortions and dynamics imposed in the nucleosome by a set of three structually different lesions that vary in GG-NER efficiencies in free DNA, and in nucleosomes [Shafirovich, Geacintov, et. al, 2019]. Two of these are bulky lesions derived from metabolic activation of the environmental carcinogen benzo[a]pyrene, the 10R (+)-cis-anti-B[a]P-N2-dG and the stereoisomeric 10S (+)-trans-anti-B[a]P-N2-dG, which respectively adopt base-displaced/intercalated and minor groove-aligned conformations in DNA. The third is a non-bulky lesion, the 5'R-8-cyclo-2'-deoxyguanosine cross-link, produced by reactive oxygen and nitrogen species; cyclopurine lesions are highly mutagenic. These adducts are placed near the dyad axis, and rotationally with the lesion-containing strand facing towards or away from the histones. While each lesion has distinct conformational characteristics that are retained in the nucleosome, a spectrum of structural and dynamic disturbances, from slight to substantial, are displayed that depend on the lesion's structure and position in the nucleosome. We hypothesize that these intrinsic structural and dynamic distinctions provide different signals to initiate the cascade of chromatin-opening processes, including acetylation and other post translational modifications, remodeling by ATP-dependent complexes and spontaneous unwrapping that regulate the rate of access to the lesion; this may translate ultimately into varying GG-NER efficiencies, including repair resistance when signals for access are too weak.
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Affiliation(s)
- Yuqin Cai
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Nicholas E Geacintov
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Suse Broyde
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA.
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17
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Hu X, Chen W, Li S, Sun J, Du K, Xia Q, Feng F. Diiron Dithiolate Complex Induced Helical Structure of Histone and Application in Photochemical Hydrogen Generation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:19691-19699. [PMID: 31117424 DOI: 10.1021/acsami.9b01866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Very-lysine-rich calf thymus histone proteins form disordered structure and hydrophobic interaction-driven aggregates in weakly acidic solution. We reported that the conjugation of diiron dithiolate complex to the lysine residues induced formation of helical conformation and condensed nanoassemblies with a high loading capacity up to 18.7 wt %. The incorporated diiron dithiolate complex showed photocatalytic activity for hydrogen evolution in aqueous solutions, with a turnover number (based on [FeFe] catalyst moiety) up to 359 that was more than 6 times that of the free catalyst. The increase of helical conformation in proteins was well correlated to the increasing enhancement of photocatalytic activity. We demonstrated that the [FeFe]-hydrogenase-mimic biohybrid system based on the photocatalyst-induced protein conformational conversion and reassembly is efficient for hydrogen generation regardless of the relatively large size.
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Affiliation(s)
- Xiantao Hu
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Weijian Chen
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Shuyi Li
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Jian Sun
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Ke Du
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Qiuyu Xia
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Fude Feng
- Key Laboratory of High Performance Polymer Material and Technology of Ministry of Education, Department of Polymer Science & Engineering, School of Chemistry & Chemical Engineering , Nanjing University , Nanjing 210023 , China
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18
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Fu I, Smith DJ, Broyde S. Rotational and translational positions determine the structural and dynamic impact of a single ribonucleotide incorporated in the nucleosome. DNA Repair (Amst) 2018; 73:155-163. [PMID: 30522887 DOI: 10.1016/j.dnarep.2018.11.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 12/13/2022]
Abstract
Ribonucleotides misincorporated by replicative DNA polymerases are by far the most common DNA lesion. The presence of ribonucleotides in DNA is associated with genome instability, causing replication stress, chromosome fragility, gross chromosomal rearrangements, and other mutagenic events. Furthermore, nucleosome and chromatin assembly as well as nucleosome positioning are affected by the presence of ribonucleotides. Notably, nucleosome formation is significantly reduced by a single ribonucleotide. Single ribonucleotides are primarily removed from DNA by the ribonucleotide excision repair (RER) pathway via the RNase H2 enzyme, which incises the DNA backbone on the 5'-side of the ribonucleotide. While the structural implications of a single ribonucleotide in free duplex DNA have been well studied, how a single ribonucleotide embedded in nucleosomal DNA impacts nucleosome structure and dynamics, and the possible consequent impact on RER, have not been explored. We have carried out 3.5 μs molecular dynamics simulations of a single ribonucleotide incorporated at various translational and rotational positions in a nucleosome core particle. We find that the presence of the 2'-OH group on the ribose impacts the local conformation and dynamics of both the ribonucleotide and nearby DNA nucleotides as well as their interactions with histones; the nature of these disturbances depends on the rotational and translational setting, including whether the ribose faces toward or away from the histones. The ribonucleotide's preferred C3'-endo pucker is stabilized by interactions with the histones, and furthermore the ribonucleotide can cause dynamic local duplex disturbance involving an abnormal C3'-endo population of the adjacent deoxyribose pucker, minor groove opening, ruptured Watson-Crick pairing, and duplex unwinding that are governed by translation-dependent histone-nucleotide interactions. Possible effects of these disturbances on RER are considered.
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Affiliation(s)
- Iwen Fu
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, United States.
| | - Duncan J Smith
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, United States.
| | - Suse Broyde
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, United States.
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19
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Abstract
The base excision repair (BER) pathway removes modified nucleobases that can be deleterious to an organism. BER is initiated by a glycosylase, which finds and removes these modified nucleobases. Most of the characterization of glycosylase activity has been conducted in the context of DNA oligomer substrates. However, DNA within eukaryotic organisms exists in a packaged environment with the basic unit of organization being the nucleosome core particle (NCP). The NCP is a complex substrate for repair in which a variety of factors can influence glycosylase activity. In this Review, we focus on the geometric positioning of modified nucleobases in an NCP and the consequences on glycosylase activity and initiating BER.
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Affiliation(s)
- Erin E Kennedy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, United States
| | - Paul J Caffrey
- Department of Chemistry, Brown University, Providence, RI 02912, United States
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, RI 02912, United States.
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20
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Cai Y, Fu I, Geacintov NE, Zhang Y, Broyde S. Synergistic effects of H3 and H4 nucleosome tails on structure and dynamics of a lesion-containing DNA: Binding of a displaced lesion partner base to the H3 tail for GG-NER recognition. DNA Repair (Amst) 2018; 65:73-78. [PMID: 29631253 PMCID: PMC5911426 DOI: 10.1016/j.dnarep.2018.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/29/2018] [Accepted: 02/26/2018] [Indexed: 02/06/2023]
Abstract
How DNA lesions in nucleosomes are recognized for global genome nucleotide excision repair (GG-NER) remains poorly understood, and the roles that histone tails may play remains to be established. Histone H3 and H4 N-terminal tails are of particular interest as their acetylation states are important in regulating nucleosomal functions in transcription, replication and repair. In particular the H3 tail has been the focus of recent attention as a site for the interaction with XPC, the GG-NER lesion recognition factor. Here we have investigated how the structure and dynamics of the DNA lesion cis-B[a]P-dG, derived from the environmental carcinogen benzo[a]pyrene (B[a]P), is impacted by the presence of flanking H3 and H4 tails. This lesion is well-repaired by GG-NER, and adopts a base-displaced/intercalated conformation in which the lesion partner C is displaced into the major groove. We used molecular dynamics simulations to obtain structural and dynamic characterizations for this lesion positioned in nucleosomal DNA so that it is bracketed by the H3 and H4 tails. The H4 tail was studied in unacetylated and acetylated states, while the H3 tail was unacetylated, its state when it binds XPC (Kakumu, Nakanishi et al., 2017). Our results reveal that upon acetylation, the H4 tail is released from the DNA surface; the H3 tail then forms a pocket that induces flipping and capture of the displaced lesion partner base C. This reveals synergistic effects of the behavior of the two tails. We hypothesize that the dual capability of the H3 tail to sense the displaced lesion partner base and to bind XPC could foster recognition of this lesion by XPC for initiation of GG-NER in nucleosomes.
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Affiliation(s)
- Yuqin Cai
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Iwen Fu
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Nicholas E Geacintov
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA
| | - Yingkai Zhang
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003, USA; NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
| | - Suse Broyde
- Department of Biology, New York University, 100 Washington Square East, New York, NY, 10003, USA.
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21
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Bilotti K, Kennedy EE, Li C, Delaney S. Human OGG1 activity in nucleosomes is facilitated by transient unwrapping of DNA and is influenced by the local histone environment. DNA Repair (Amst) 2017; 59:1-8. [PMID: 28892740 DOI: 10.1016/j.dnarep.2017.08.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 12/17/2022]
Abstract
If unrepaired, damage to genomic DNA can cause mutations and/or be cytotoxic. Single base lesions are repaired via the base excision repair (BER) pathway. The first step in BER is the recognition and removal of the nucleobase lesion by a glycosylase enzyme. For example, human oxoguanine glycosylase 1 (hOGG1) is responsible for removal of the prototypic oxidatively damaged nucleobase, 8-oxo-7,8-dihydroguanine (8-oxoG). To date, most studies of glycosylases have used free duplex DNA substrates. However, cellular DNA is packaged as repeating nucleosome units, with 145 base pair segments of DNA wrapped around histone protein octamers. Previous studies revealed inhibition of hOGG1 at the nucleosome dyad axis and in the absence of chromatin remodelers. In this study, we reveal that even in the absence of chromatin remodelers or external cofactors, hOGG1 can initiate BER at positions off the dyad axis and that this activity is facilitated by spontaneous and transient unwrapping of DNA from the histones. Additionally, we find that solution accessibility as determined by hydroxyl radical footprinting is not fully predictive of glycosylase activity and that histone tails can suppress hOGG1 activity. We therefore suggest that local nuances in the nucleosome environment and histone-DNA interactions can impact glycosylase activity.
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Affiliation(s)
- Katharina Bilotti
- Department of Chemistry, Brown University, Providence, RI 02912, United States
| | - Erin E Kennedy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, United States
| | - Chuxuan Li
- Department of Chemistry, Brown University, Providence, RI 02912, United States
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, RI 02912, United States.
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