1
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Forni D, Pozzoli U, Mozzi A, Cagliani R, Sironi M. Depletion of CpG dinucleotides in bacterial genomes may represent an adaptation to high temperatures. NAR Genom Bioinform 2024; 6:lqae088. [PMID: 39071851 PMCID: PMC11282364 DOI: 10.1093/nargab/lqae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/17/2024] [Accepted: 07/18/2024] [Indexed: 07/30/2024] Open
Abstract
Dinucleotide biases have been widely investigated in the genomes of eukaryotes and viruses, but not in bacteria. We assembled a dataset of bacterial genomes (>15 000), which are representative of the genetic diversity in the kingdom Eubacteria, and we analyzed dinucleotide biases in relation to different traits. We found that TpA dinucleotides are the most depleted and that CpG dinucleotides show the widest dispersion. The abundances of both dinucleotides vary with genomic G + C content and show a very strong phylogenetic signal. After accounting for G + C content and phylogenetic inertia, we analyzed different bacterial lifestyle traits. We found that temperature preferences associate with the abundance of CpG dinucleotides, with thermophiles/hyperthemophiles being particularly depleted. Conversely, the TpA dinucleotide displays a bias that only depends on genomic G + C composition. Using predictions of intrinsic cyclizability we also show that CpG depletion may associate with higher DNA bendability in both thermophiles/hyperthermophiles and mesophiles, and that the former are predicted to have significantly more flexible genomes than the latter. We suggest that higher bendability is advantageous at high temperatures because it facilitates DNA positive supercoiling and that, through modulation of DNA mechanical properties, local or global CpG depletion controls genome organization, most likely not only in bacteria.
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Affiliation(s)
- Diego Forni
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, 23842 Bosisio Parini, Italy
| | - Uberto Pozzoli
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, 23842 Bosisio Parini, Italy
| | - Alessandra Mozzi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, 23842 Bosisio Parini, Italy
| | - Rachele Cagliani
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, 23842 Bosisio Parini, Italy
| | - Manuela Sironi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, 23842 Bosisio Parini, Italy
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2
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Rekvig OP. The greatest contribution to medical science is the transformation from studying symptoms to studying their causes-the unrelenting legacy of Robert Koch and Louis Pasteur-and a causality perspective to approach a definition of SLE. Front Immunol 2024; 15:1346619. [PMID: 38361929 PMCID: PMC10867267 DOI: 10.3389/fimmu.2024.1346619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/10/2024] [Indexed: 02/17/2024] Open
Abstract
The basic initiative related to this study is derived from the fact that systemic lupus erythematosus (SLE) is a unique and fertile system science subject. We are, however, still far from understanding its nature. It may be fair to indicate that we are spending more time and resources on studying the complexity of classified SLE than studying the validity of classification criteria. This study represents a theoretical analysis of current instinctual SLE classification criteria based on "the causality principle." The discussion has its basis on the radical scientific traditions introduced by Robert Koch and Louis Pasteur. They announced significant changes in our thinking of disease etiology through the implementation of the modern version of "the causality principle." They influenced all aspects of today's medical concepts and research: the transformation of medical science from studies of symptoms to study their causes, relevant for monosymptomatic diseases as for syndromes. Their studies focused on bacteria as causes of infectious diseases and on how the immune system adapts to control and prevent contagious spreading. This is the most significant paradigm shift in the modern history of medicine and resulted in radical changes in our view of the immune system. They described acquired post-infection immunity and active immunization by antigen-specific vaccines. The paradigm "transformation" has a great theoretical impact also on current studies of autoimmune diseases like SLE: symptoms and their cause(s). In this study, the evolution of SLE classification and diagnostic criteria is discussed from "the causality principle" perspective, and if contemporary SLE classification criteria are as useful as believed today for SLE research. This skepticism is based on the fact that classification criteria are not selected based on cogent causal strategies. The SLE classification criteria do not harmonize with Koch's and Pasteur's causality principle paradigms and not with Witebsky's Koch-derived postulates for autoimmune and infectious diseases. It is not established whether the classification criteria can separate SLE as a "one disease entity" from "SLE-like non-SLE disorders"-the latter in terms of SLE imitations. This is discussed here in terms of weight, rank, and impact of the classification criteria: Do they all originate from "one basic causal etiology"? Probably not.
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Affiliation(s)
- Ole Petter Rekvig
- Section for Autoimmunity, Fürst Medical Laboratory, Oslo, Norway
- Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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3
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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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4
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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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5
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Sharma R, Patelli AS, Bruin LD, Maddocks JH. cgNA+web : A visual interface to the cgNA+ sequence-dependent statistical mechanics model of double-stranded nucleic acids. J Mol Biol 2023. [DOI: 10.1016/j.jmb.2023.167978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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6
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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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7
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Rekvig OP. The Anti-DNA Antibodies: Their Specificities for Unique DNA Structures and Their Unresolved Clinical Impact-A System Criticism and a Hypothesis. Front Immunol 2022; 12:808008. [PMID: 35087528 PMCID: PMC8786728 DOI: 10.3389/fimmu.2021.808008] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022] Open
Abstract
Systemic lupus erythematosus (SLE) is diagnosed and classified by criteria, or by experience, intuition and traditions, and not by scientifically well-defined etiology(ies) or pathogenicity(ies). One central criterion and diagnostic factor is founded on theoretical and analytical approaches based on our imperfect definition of the term “The anti-dsDNA antibody”. “The anti-dsDNA antibody” holds an archaic position in SLE as a unique classification criterium and pathogenic factor. In a wider sense, antibodies to unique transcriptionally active or silent DNA structures and chromatin components may have individual and profound nephritogenic impact although not considered yet – not in theoretical nor in descriptive or experimental contexts. This hypothesis is contemplated here. In this analysis, our state-of-the-art conception of these antibodies is probed and found too deficient with respect to their origin, structural DNA specificities and clinical/pathogenic impact. Discoveries of DNA structures and functions started with Miescher’s Nuclein (1871), via Chargaff, Franklin, Watson and Crick, and continues today. The discoveries have left us with a DNA helix that presents distinct structures expressing unique operations of DNA. All structures are proven immunogenic! Unique autoimmune antibodies are described against e.g. ssDNA, elongated B DNA, bent B DNA, Z DNA, cruciform DNA, or individual components of chromatin. In light of the massive scientific interest in anti-DNA antibodies over decades, it is an unexpected observation that the spectrum of DNA structures has been known for decades without being implemented in clinical immunology. This leads consequently to a critical analysis of historical and contemporary evidence-based data and of ignored and one-dimensional contexts and hypotheses: i.e. “one antibody - one disease”. In this study radical viewpoints on the impact of DNA and chromatin immunity/autoimmunity are considered and discussed in context of the pathogenesis of lupus nephritis.
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Affiliation(s)
- Ole Petter Rekvig
- Section of Autoimmunity, Fürst Medical Laboratory, Oslo, Norway.,Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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8
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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: 16] [Impact Index Per Article: 8.0] [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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9
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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: 3] [Impact Index Per Article: 1.0] [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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10
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Loop-seq: A high-throughput technique to measure the mesoscale mechanical properties of DNA. Methods Enzymol 2021; 661:305-326. [PMID: 34776217 DOI: 10.1016/bs.mie.2021.08.011] [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] [Indexed: 12/12/2022]
Abstract
The local mechanical properties of the DNA polymer influence molecular processes in biology that require mechanical deformations of DNA. Lack of suitable high-throughput experimental techniques had precluded measuring how these properties might vary with sequence along the vast lengths of genomes. Here, we present a detailed protocol for a recently developed experimental technique called loop-seq, which measures at least one local mechanical property of DNA-its propensity to cyclize-in genome-scale throughput. Loop-seq has been used to obtain experimentally derived genome-wide maps of a physical property of DNA. Such measurements have revealed that diverse DNA-deforming processes involved in chromatin organization at various genomic loci are regulated by the genetically encoded, sequence-dependent variations in the mechanical properties of DNA.
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11
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Basu A, Bobrovnikov DG, Ha T. DNA mechanics and its biological impact. J Mol Biol 2021; 433:166861. [PMID: 33539885 DOI: 10.1016/j.jmb.2021.166861] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 02/06/2023]
Abstract
Almost all nucleoprotein interactions and DNA manipulation events involve mechanical deformations of DNA. Extraordinary progresses in single-molecule, structural, and computational methods have characterized the average mechanical properties of DNA, such as bendability and torsional rigidity, in high resolution. Further, the advent of sequencing technology has permitted measuring, in high-throughput, how such mechanical properties vary with sequence and epigenetic modifications along genomes. We review these recent technological advancements, and discuss how they have contributed to the emerging idea that variations in the mechanical properties of DNA play a fundamental role in regulating, genome-wide, diverse processes involved in chromatin organization.
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Affiliation(s)
- Aakash Basu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Dmitriy G Bobrovnikov
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA
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12
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Marzec M. Uncovering the Mechanical Code of DNA Using 'Loop-seq'. Trends Genet 2021; 37:494-495. [PMID: 33622494 DOI: 10.1016/j.tig.2021.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 11/18/2022]
Abstract
DNA mechanical properties play a critical role in different biological processes. Basu and coworkers described a method that measures DNA mechanics on the genome scale. Access to a high-throughput tool for measuring DNA mechanics opens up new possibilities to investigate this phenomenon with respect to establishing the chromatin regulatory landscape.
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Affiliation(s)
- Marek Marzec
- University of Silesia in Katowice, Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, Jagiellonska 28, 40-032 Katowice, Poland.
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13
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Basu A, Bobrovnikov DG, Qureshi Z, Kayikcioglu T, Ngo TTM, Ranjan A, Eustermann S, Cieza B, Morgan MT, Hejna M, Rube HT, Hopfner KP, Wolberger C, Song JS, Ha T. Measuring DNA mechanics on the genome scale. Nature 2021; 589:462-467. [PMID: 33328628 PMCID: PMC7855230 DOI: 10.1038/s41586-020-03052-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 10/21/2020] [Indexed: 12/21/2022]
Abstract
Mechanical deformations of DNA such as bending are ubiquitous and have been implicated in diverse cellular functions1. However, the lack of high-throughput tools to measure the mechanical properties of DNA has limited our understanding of how DNA mechanics influence chromatin transactions across the genome. Here we develop 'loop-seq'-a high-throughput assay to measure the propensity for DNA looping-and determine the intrinsic cyclizabilities of 270,806 50-base-pair DNA fragments that span Saccharomyces cerevisiae chromosome V, other genomic regions, and random sequences. We found sequence-encoded regions of unusually low bendability within nucleosome-depleted regions upstream of transcription start sites (TSSs). Low bendability of linker DNA inhibits nucleosome sliding into the linker by the chromatin remodeller INO80, which explains how INO80 can define nucleosome-depleted regions in the absence of other factors2. Chromosome-wide, nucleosomes were characterized by high DNA bendability near dyads and low bendability near linkers. This contrast increases for deeper gene-body nucleosomes but disappears after random substitution of synonymous codons, which suggests that the evolution of codon choice has been influenced by DNA mechanics around gene-body nucleosomes. Furthermore, we show that local DNA mechanics affect transcription through TSS-proximal nucleosomes. Overall, this genome-scale map of DNA mechanics indicates a 'mechanical code' with broad functional implications.
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Affiliation(s)
- Aakash Basu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Dmitriy G Bobrovnikov
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zan Qureshi
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Tunc Kayikcioglu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Thuy T M Ngo
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Anand Ranjan
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Sebastian Eustermann
- Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
- Gene Center, Ludwig-Maximilians-Universität, Munich, Germany
| | - Basilio Cieza
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Michael T Morgan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Miroslav Hejna
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - H Tomas Rube
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Karl-Peter Hopfner
- Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
- Gene Center, Ludwig-Maximilians-Universität, Munich, Germany
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jun S Song
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Cancer Center at Illinois, University of Illinois, Urbana, IL, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 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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14
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Jeong J, Kim HD. Determinants of cyclization-decyclization kinetics of short DNA with sticky ends. Nucleic Acids Res 2020; 48:5147-5156. [PMID: 32282905 PMCID: PMC7229855 DOI: 10.1093/nar/gkaa207] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 03/17/2020] [Accepted: 03/25/2020] [Indexed: 12/16/2022] Open
Abstract
Cyclization of DNA with sticky ends is commonly used to measure DNA bendability as a function of length and sequence, but how its kinetics depend on the rotational positioning of the sticky ends around the helical axis is less clear. Here, we measured cyclization (looping) and decyclization (unlooping) rates (kloop and kunloop) of DNA with sticky ends over three helical periods (100-130 bp) using single-molecule fluorescence resonance energy transfer (FRET). kloop showed a nontrivial undulation as a function of DNA length whereas kunloop showed a clear oscillation with a period close to the helical turn of DNA (∼10.5 bp). The oscillation of kunloop was almost completely suppressed in the presence of gaps around the sticky ends. We explain these findings by modeling double-helical DNA as a twisted wormlike chain with a finite width, intrinsic curvature, and stacking interaction between the end base pairs. We also discuss technical issues for converting the FRET-based cyclization/decyclization rates to an equilibrium quantity known as the J factor that is widely used to characterize DNA bending mechanics.
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Affiliation(s)
- Jiyoun Jeong
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430, USA
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430, USA
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15
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De Bruin L, Maddocks JH. cgDNAweb: a web interface to the cgDNA sequence-dependent coarse-grain model of double-stranded DNA. Nucleic Acids Res 2019; 46:W5-W10. [PMID: 29905876 PMCID: PMC6030996 DOI: 10.1093/nar/gky351] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 05/09/2018] [Indexed: 12/13/2022] Open
Abstract
The sequence-dependent statistical mechanical properties of fragments of double-stranded DNA is believed to be pertinent to its biological function at length scales from a few base pairs (or bp) to a few hundreds of bp, e.g. indirect read-out protein binding sites, nucleosome positioning sequences, phased A-tracts, etc. In turn, the equilibrium statistical mechanics behaviour of DNA depends upon its ground state configuration, or minimum free energy shape, as well as on its fluctuations as governed by its stiffness (in an appropriate sense). We here present cgDNAweb, which provides browser-based interactive visualization of the sequence-dependent ground states of double-stranded DNA molecules, as predicted by the underlying cgDNA coarse-grain rigid-base model of fragments with arbitrary sequence. The cgDNAweb interface is specifically designed to facilitate comparison between ground state shapes of different sequences. The server is freely available at cgDNAweb.epfl.ch with no login requirement.
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Affiliation(s)
- Lennart De Bruin
- Instituut-Lorentz for Theoretical Physics, Leiden University, P.O. Box 9506, 2300 RA Leiden, The Netherlands
| | - John H Maddocks
- Institut de Mathématiques, Station 8, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
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16
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Harrison RM, Romano F, Ouldridge TE, Louis AA, Doye JPK. Identifying Physical Causes of Apparent Enhanced Cyclization of Short DNA Molecules with a Coarse-Grained Model. J Chem Theory Comput 2019; 15:4660-4672. [PMID: 31282669 PMCID: PMC6694408 DOI: 10.1021/acs.jctc.9b00112] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
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DNA
cyclization is a powerful technique to gain insight into the nature
of DNA bending. While the wormlike chain model provides a good description
of small to moderate bending fluctuations, it is expected to break
down for large bending. Recent cyclization experiments on strongly
bent shorter molecules indeed suggest enhanced flexibility over and
above that expected from the wormlike chain. Here, we use a coarse-grained
model of DNA to investigate the subtle thermodynamics of DNA cyclization
for molecules ranging from 30 to 210 base pairs. As the molecules
get shorter, we find increasing deviations between our computed equilibrium j-factor and the classic wormlike chain predictions of Shimada
and Yamakawa for a torsionally aligned looped molecule. These deviations
are due to sharp kinking, first at nicks, and only subsequently in
the body of the duplex. At the shortest lengths, substantial fraying
at the ends of duplex domains is the dominant method of relaxation.
We also estimate the dynamic j-factor measured in
recent FRET experiments. We find that the dynamic j-factor is systematically larger than its equilibrium counterpart—with
the deviation larger for shorter molecules—because not all
the stress present in the fully cyclized state is present in the transition
state. These observations are important for the interpretation of
recent cyclization experiments, suggesting that measured anomalously
high j-factors may not necessarily indicate non-WLC
behavior in the body of duplexes.
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Affiliation(s)
- Ryan M Harrison
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry , University of Oxford , South Parks Road , Oxford OX1 3QZ , United Kingdom
| | - Flavio Romano
- Dipartimento di Scienze Molecolari e Nanosistemi , Universitá Ca' Foscari Venezia , I-30123 Venezia , Italy
| | - Thomas E Ouldridge
- Imperial College Centre for Synthetic Biology and Department of Bioengineering , Imperial College London , 180 Queen's Road , London SW7 2AZ , United Kingdom
| | - Ard A Louis
- Rudolf Peierls Centre for Theoretical Physics, Department of Physics , University of Oxford , 1 Keble Road , Oxford OX1 3NP , United Kingdom
| | - Jonathan P K Doye
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry , University of Oxford , South Parks Road , Oxford OX1 3QZ , United Kingdom
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17
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Abstract
The elasticity of the DNA double helix varies with the underlying base pair sequence. This allows one to put mechanical cues into sequences that in turn influence the packaging of DNA into nucleosomes, DNA-wrapped protein cylinders. Nucleosomes dictate a broad range of biological processes, ranging from gene regulation, recombination, and replication to chromosome condensation. Here we map base pair sequences onto graphs and use shortest paths algorithms to determine which DNA stretches are easiest or hardest to bend inside a nucleosome. We further demonstrate how genetic and mechanical information can be multiplexed by studying paths through graphs of synonymous codons. Using this method we find that nucleosomes can be placed by mechanical cues nearly everywhere on the genome of baker's yeast (Saccharomyces cerevisiae).
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Affiliation(s)
- Martijn Zuiddam
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands
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18
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Wondergem JAJ, Schiessel H, Tompitak M. Performing SELEX experimentsin silico. J Chem Phys 2017; 147:174101. [DOI: 10.1063/1.5001394] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- J. A. J. Wondergem
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - H. Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - M. Tompitak
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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19
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Alexandrov LB, Rasmussen KØ, Bishop AR, Alexandrov BS. Evaluating the role of coherent delocalized phonon-like modes in DNA cyclization. Sci Rep 2017; 7:9731. [PMID: 28851939 PMCID: PMC5575098 DOI: 10.1038/s41598-017-09537-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 07/27/2017] [Indexed: 12/11/2022] Open
Abstract
The innate flexibility of a DNA sequence is quantified by the Jacobson-Stockmayer's J-factor, which measures the propensity for DNA loop formation. Recent studies of ultra-short DNA sequences revealed a discrepancy of up to six orders of magnitude between experimentally measured and theoretically predicted J-factors. These large differences suggest that, in addition to the elastic moduli of the double helix, other factors contribute to loop formation. Here, we develop a new theoretical model that explores how coherent delocalized phonon-like modes in DNA provide single-stranded "flexible hinges" to assist in loop formation. We combine the Czapla-Swigon-Olson structural model of DNA with our extended Peyrard-Bishop-Dauxois model and, without changing any of the parameters of the two models, apply this new computational framework to 86 experimentally characterized DNA sequences. Our results demonstrate that the new computational framework can predict J-factors within an order of magnitude of experimental measurements for most ultra-short DNA sequences, while continuing to accurately describe the J-factors of longer sequences. Further, we demonstrate that our computational framework can be used to describe the cyclization of DNA sequences that contain a base pair mismatch. Overall, our results support the conclusion that coherent delocalized phonon-like modes play an important role in DNA cyclization.
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Affiliation(s)
- Ludmil B Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
- University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, 87102, USA
| | - Kim Ø Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
| | - Boian S Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America.
- University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, 87102, USA.
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20
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Tompitak M, Barkema GT, Schiessel H. Benchmarking and refining probability-based models for nucleosome-DNA interaction. BMC Bioinformatics 2017; 18:157. [PMID: 28270095 PMCID: PMC5341481 DOI: 10.1186/s12859-017-1569-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 02/24/2017] [Indexed: 01/30/2023] Open
Abstract
Background In investigations of nucleosome positioning preferences, a model that assigns an affinity to a given sequence is necessary to make predictions. One important class of models, which treats a nucleosome sequence as a Markov chain, has been applied with success when informed with experimentally measured nucleosomal sequence preferences. Results We find that we can also use such models as a fast approximative scheme for computationally expensive biophysical models, vastly increasing their reach. Employing these models in this way also allows us to benchmark them for the first time. Doing so for the approximative in silico models indirectly tells us about the accuracy we can expect of them when applied to real data. Conclusion We find that models presented in the literature should perform well, but this performance depends on factors such as the order of the Markov model, the preprocessing of the probability distributions on which the model is based, and the size and quality of the sequence ensemble from which those distributions are calculated. Electronic supplementary material The online version of this article (doi:10.1186/s12859-017-1569-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marco Tompitak
- Lorentz Institute, Leiden University, Niels Bohrweg 2, Leiden, 2333CA, The Netherlands.
| | - Gerard T Barkema
- Institute for Theoretical Physics, Utrecht University, Princetonplein 5, Utrecht, 3584CC, The Netherlands
| | - Helmut Schiessel
- Lorentz Institute, Leiden University, Niels Bohrweg 2, Leiden, 2333CA, The Netherlands
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21
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Multiplexing Genetic and Nucleosome Positioning Codes: A Computational Approach. PLoS One 2016; 11:e0156905. [PMID: 27272176 PMCID: PMC4896621 DOI: 10.1371/journal.pone.0156905] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/20/2016] [Indexed: 11/19/2022] Open
Abstract
Eukaryotic DNA is strongly bent inside fundamental packaging units: the nucleosomes. It is known that their positions are strongly influenced by the mechanical properties of the underlying DNA sequence. Here we discuss the possibility that these mechanical properties and the concomitant nucleosome positions are not just a side product of the given DNA sequence, e.g. that of the genes, but that a mechanical evolution of DNA molecules might have taken place. We first demonstrate the possibility of multiplexing classical and mechanical genetic information using a computational nucleosome model. In a second step we give evidence for genome-wide multiplexing in Saccharomyces cerevisiae and Schizosacharomyces pombe. This suggests that the exact positions of nucleosomes play crucial roles in chromatin function.
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Alexandrov LB, Bishop AR, Rasmussen KØ, Alexandrov BS. The role of structural parameters in DNA cyclization. BMC Bioinformatics 2016; 17:68. [PMID: 26846597 PMCID: PMC4743258 DOI: 10.1186/s12859-016-0897-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/20/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The intrinsic bendability of DNA plays an important role with relevance for myriad of essential cellular mechanisms. The flexibility of a DNA fragment can be experimentally and computationally examined by its propensity for cyclization, quantified by the Jacobson-Stockmayer J factor. In this study, we use a well-established coarse-grained three-dimensional model of DNA and seven distinct sets of experimentally and computationally derived conformational parameters of the double helix to evaluate the role of structural parameters in calculating DNA cyclization. RESULTS We calculate the cyclization rates of 86 DNA sequences with previously measured J factors and lengths between 57 and 325 bp as well as of 20,000 randomly generated DNA sequences with lengths between 350 and 4000 bp. Our comparison with experimental data is complemented with analysis of simulated data. CONCLUSIONS Our data demonstrate that all sets of parameters yield very similar results for longer DNA fragments, regardless of the nucleotide sequence, which are in agreement with experimental measurements. However, for DNA fragments shorter than 100 bp, all sets of parameters performed poorly yielding results with several orders of magnitude difference from the experimental measurements. Our data show that DNA cyclization rates calculated using conformational parameters based on nucleosome packaging data are most similar to the experimental measurements. Overall, our study provides a comprehensive large-scale assessment of the role of structural parameters in calculating DNA cyclization rates.
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Affiliation(s)
- Ludmil B Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA. .,Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Kim Ø Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
| | - Boian S Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
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