1
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Kabir A, Bhattarai M, Peterson S, Najman-Licht Y, Rasmussen KØ, Shehu A, Bishop AR, Alexandrov B, Usheva A. DNA breathing integration with deep learning foundational model advances genome-wide binding prediction of human transcription factors. Nucleic Acids Res 2024:gkae783. [PMID: 39271116 DOI: 10.1093/nar/gkae783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 08/21/2024] [Accepted: 08/29/2024] [Indexed: 09/15/2024] Open
Abstract
It was previously shown that DNA breathing, thermodynamic stability, as well as transcriptional activity and transcription factor (TF) bindings are functionally correlated. To ascertain the precise relationship between TF binding and DNA breathing, we developed the multi-modal deep learning model EPBDxDNABERT-2, which is based on the Extended Peyrard-Bishop-Dauxois (EPBD) nonlinear DNA dynamics model. To train our EPBDxDNABERT-2, we used chromatin immunoprecipitation sequencing (ChIP-Seq) data comprising 690 ChIP-seq experimental results encompassing 161 distinct TFs and 91 human cell types. EPBDxDNABERT-2 significantly improves the prediction of over 660 TF-DNA, with an increase in the area under the receiver operating characteristic (AUROC) metric of up to 9.6% when compared to the baseline model that does not leverage DNA biophysical properties. We expanded our analysis to in vitro high-throughput Systematic Evolution of Ligands by Exponential enrichment (HT-SELEX) dataset of 215 TFs from 27 families, comparing EPBD with established frameworks. The integration of the DNA breathing features with DNABERT-2 foundational model, greatly enhanced TF-binding predictions. Notably, EPBDxDNABERT-2, trained on a large-scale multi-species genomes, with a cross-attention mechanism, improved predictive power shedding light on the mechanisms underlying disease-related non-coding variants discovered in genome-wide association studies.
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Affiliation(s)
- Anowarul Kabir
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
- Department of Computer Science, George Mason University, 4400 University Dr, 22030 VA, USA
| | - Manish Bhattarai
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
| | - Selma Peterson
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
| | | | - Kim Ø Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
| | - Amarda Shehu
- Department of Computer Science, George Mason University, 4400 University Dr, 22030 VA, USA
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
| | - Boian Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544 NM, USA
| | - Anny Usheva
- Department of Surgery, Brown University, 69 Brown St Box 1822, 02912 RI, USA
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2
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Smirnov E, Molínová P, Chmúrčiaková N, Vacík T, Cmarko D. Non-canonical DNA structures in the human ribosomal DNA. Histochem Cell Biol 2023; 160:499-515. [PMID: 37750997 DOI: 10.1007/s00418-023-02233-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 09/27/2023]
Abstract
Non-canonical structures (NCS) refer to the various forms of DNA that differ from the B-conformation described by Watson and Crick. It has been found that these structures are usual components of the genome, actively participating in its essential functions. The present review is focused on the nine kinds of NCS appearing or likely to appear in human ribosomal DNA (rDNA): supercoiling structures, R-loops, G-quadruplexes, i-motifs, DNA triplexes, cruciform structures, DNA bubbles, and A and Z DNA conformations. We discuss the conditions of their generation, including their sequence specificity, distribution within the locus, dynamics, and beneficial and detrimental role in the cell.
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Affiliation(s)
- Evgeny Smirnov
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic.
| | - Pavla Molínová
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Nikola Chmúrčiaková
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Tomáš Vacík
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Dušan Cmarko
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
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3
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Kabir A, Bhattarai M, Rasmussen KØ, Shehu A, Usheva A, Bishop AR, Alexandrov B. Examining DNA breathing with pyDNA-EPBD. Bioinformatics 2023; 39:btad699. [PMID: 37991847 PMCID: PMC10681863 DOI: 10.1093/bioinformatics/btad699] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/23/2023] [Accepted: 11/21/2023] [Indexed: 11/24/2023] Open
Abstract
MOTIVATION The two strands of the DNA double helix locally and spontaneously separate and recombine in living cells due to the inherent thermal DNA motion. This dynamics results in transient openings in the double helix and is referred to as "DNA breathing" or "DNA bubbles." The propensity to form local transient openings is important in a wide range of biological processes, such as transcription, replication, and transcription factors binding. However, the modeling and computer simulation of these phenomena, have remained a challenge due to the complex interplay of numerous factors, such as, temperature, salt content, DNA sequence, hydrogen bonding, base stacking, and others. RESULTS We present pyDNA-EPBD, a parallel software implementation of the Extended Peyrard-Bishop-Dauxois (EPBD) nonlinear DNA model that allows us to describe some features of DNA dynamics in detail. The pyDNA-EPBD generates genomic scale profiles of average base-pair openings, base flipping probability, DNA bubble probability, and calculations of the characteristically dynamic length indicating the number of base pairs statistically significantly affected by a single point mutation using the Markov Chain Monte Carlo algorithm. AVAILABILITY AND IMPLEMENTATION pyDNA-EPBD is supported across most operating systems and is freely available at https://github.com/lanl/pyDNA_EPBD. Extensive documentation can be found at https://lanl.github.io/pyDNA_EPBD/.
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Affiliation(s)
- Anowarul Kabir
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, United States
- Department of Computer Science, George Mason University, Fairfax, VA 22030, United States
| | - Manish Bhattarai
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, United States
| | - Kim Ø Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, United States
| | - Amarda Shehu
- Department of Computer Science, George Mason University, Fairfax, VA 22030, United States
| | - Anny Usheva
- Department of Surgery, Brown University, Providence, RI 02912, United States
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, United States
| | - Boian Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, United States
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4
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Genthon A, Dvirnas A, Ambjörnsson T. Equilibrium melting probabilities of a DNA molecule with a defect: An exact solution of the Poland-Scheraga model. J Chem Phys 2023; 159:145102. [PMID: 37815110 DOI: 10.1063/5.0168915] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/20/2023] [Indexed: 10/11/2023] Open
Abstract
In this study we derive analytically the equilibrium melting probabilities for basepairs of a DNA molecule with a defect site. We assume that the defect is characterized by a change in the Watson-Crick basepair energy of the defect basepair, and in the associated two stacking energies for the defect, as compared to the remaining parts of the DNA. The defect site could, for instance, occur due to DNA basepair mismatching, cross-linking, or by the chemical modifications when attaching fluorescent labels, such as fluorescent-quencher pairs, to DNA. Our exact solution of the Poland-Scheraga model for DNA melting provides the probability that the labeled basepair, and its neighbors, are open at different temperatures. Our work is of direct importance, for instance, for studies where fluorophore-quencher pairs are used for studying single basepair fluctuations of designed DNA molecules.
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Affiliation(s)
- Arthur Genthon
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Albertas Dvirnas
- Computational Biology and Biological Physics, Centre for Environmental and Climate Science, Lund University, SE-223 62 Lund, Sweden
| | - Tobias Ambjörnsson
- Computational Biology and Biological Physics, Centre for Environmental and Climate Science, Lund University, SE-223 62 Lund, Sweden
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5
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Kabir A, Bhattarai M, Rasmussen KØ, Shehu A, Usheva A, Bishop AR, Alexandrov BS. Examining DNA Breathing with pyDNA-EPBD. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.09.557010. [PMID: 37745370 PMCID: PMC10515784 DOI: 10.1101/2023.09.09.557010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Motivation The two strands of the DNA double helix locally and spontaneously separate and recombine in living cells due to the inherent thermal DNA motion.This dynamics results in transient openings in the double helix and is referred to as "DNA breathing" or "DNA bubbles." The propensity to form local transient openings is important in a wide range of biological processes, such as transcription, replication, and transcription factors binding. However, the modeling and computer simulation of these phenomena, have remained a challenge due to the complex interplay of numerous factors, such as, temperature, salt content, DNA sequence, hydrogen bonding, base stacking, and others. Results We present pyDNA-EPBD, a parallel software implementation of the Extended Peyrard-Bishop- Dauxois (EPBD) nonlinear DNA model that allows us to describe some features of DNA dynamics in detail. The pyDNA-EPBD generates genomic scale profiles of average base-pair openings, base flipping probability, DNA bubble probability, and calculations of the characteristically dynamic length indicating the number of base pairs statistically significantly affected by a single point mutation using the Markov Chain Monte Carlo (MCMC) algorithm.
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Affiliation(s)
- Anowarul Kabir
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544, NM, 87102
- George Mason University, 4400 University Dr, Fairfax, VA 22030
| | - Manish Bhattarai
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544, NM, 87102
| | - Kim Ø. Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544, NM, 87102
| | - Amarda Shehu
- George Mason University, 4400 University Dr, Fairfax, VA 22030
| | - Anny Usheva
- Brown University, 69 Brown St Box 1822, Providence, RI 02912
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544, NM, 87102
| | - Boian S Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87544, NM, 87102
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6
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Bubble Relaxation Dynamics in Homopolymer DNA Sequences. Molecules 2023; 28:molecules28031041. [PMID: 36770707 PMCID: PMC9920605 DOI: 10.3390/molecules28031041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/11/2023] [Accepted: 01/15/2023] [Indexed: 01/22/2023] Open
Abstract
Understanding the inherent timescales of large bubbles in DNA is critical to a thorough comprehension of its physicochemical characteristics, as well as their potential role on helix opening and biological function. In this work, we employ the coarse-grained Peyrard-Bishop-Dauxois model of DNA to study relaxation dynamics of large bubbles in homopolymer DNA, using simulations up to the microsecond time scale. By studying energy autocorrelation functions of relatively large bubbles inserted into thermalised DNA molecules, we extract characteristic relaxation times from the equilibration process for both adenine-thymine (AT) and guanine-cytosine (GC) homopolymers. Bubbles of different amplitudes and widths are investigated through extensive statistics and appropriate fittings of their relaxation. Characteristic relaxation times increase with bubble amplitude and width. We show that, within the model, relaxation times are two orders of magnitude longer in GC sequences than in AT sequences. Overall, our results confirm that large bubbles leave a lasting impact on the molecule's dynamics, for times between 0.5-500 ns depending on the homopolymer type and bubble shape, thus clearly affecting long-time evolutions of the molecule.
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7
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Barbero-Aparicio JA, Cuesta-Lopez S, García-Osorio CI, Pérez-Rodríguez J, García-Pedrajas N. Nonlinear physics opens a new paradigm for accurate transcription start site prediction. BMC Bioinformatics 2022; 23:565. [PMID: 36585618 PMCID: PMC9801560 DOI: 10.1186/s12859-022-05129-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 12/27/2022] [Indexed: 12/31/2022] Open
Abstract
There is evidence that DNA breathing (spontaneous opening of the DNA strands) plays a relevant role in the interactions of DNA with other molecules, and in particular in the transcription process. Therefore, having physical models that can predict these openings is of interest. However, this source of information has not been used before either in transcription start sites (TSSs) or promoter prediction. In this article, one such model is used as an additional information source that, when used by a machine learning (ML) model, improves the results of current methods for the prediction of TSSs. In addition, we provide evidence on the validity of the physical model, as it is able by itself to predict TSSs with high accuracy. This opens an exciting avenue of research at the intersection of statistical mechanics and ML, where ML models in bioinformatics can be improved using physical models of DNA as feature extractors.
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Affiliation(s)
- José Antonio Barbero-Aparicio
- grid.23520.360000 0000 8569 1592Departamento de Informática, Universidad de Burgos, Avda. de Cantabria s/n, 09006 Burgos, Spain
| | - Santiago Cuesta-Lopez
- grid.23520.360000 0000 8569 1592Universidad de Burgos, Hospital del Rey, s/n, 09001 Burgos, Spain ,ICAMCyL Foundation, Internacional Center for Advanced Materials and Raw Materials of Castilla y León, León Technology Park, main building, first floor, offices 106-108, C/Julia Morros s/n, Armunia, 24009 León, Spain
| | - César Ignacio García-Osorio
- grid.23520.360000 0000 8569 1592Departamento de Informática, Universidad de Burgos, Avda. de Cantabria s/n, 09006 Burgos, Spain
| | - Javier Pérez-Rodríguez
- grid.449008.10000 0004 1795 4150Departamento de Métodos Cuantitativos, Universidad de Loyola Andalucía, Escritor Castilla Aguayo, 4, 14004 Córdoba, Spain
| | - Nicolás García-Pedrajas
- grid.411901.c0000 0001 2183 9102Department of Computing and Numerical Analysis, University of Córdoba, Edificio Albert Einstein, Campus de Rabanales, 14071 Córdoba, Spain
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8
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Zoli M. Non-linear Hamiltonian models for DNA. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2022; 51:431-447. [PMID: 35976412 DOI: 10.1007/s00249-022-01614-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Nucleic acids' physical properties have been investigated by theoretical methods based both on fully atomistic representations and on coarse-grained models, e.g., the worm-like-chain, taken from polymer physics. In this review article, I discuss an intermediate (mesoscopic) approach and show how to build a three-dimensional Hamiltonian model which accounts for the main interactions responsible for the stability of the helical molecules. While the 3D mesoscopic model yields a sufficiently detailed description of the helix at the level of the base pair, it also allows one to predict the thermodynamical and structural properties of molecules in solution. Relying on the idea that the base pair fluctuations can be conceived as trajectories, I have built over the past years a computational method based on the time-dependent path integral formalism to derive the partition function. While the main features of the method are presented, I focus here in particular on a newly developed statistical method to set the maximum amplitude of the base pair fluctuations, a key parameter of the theory. Some applications to the calculation of DNA flexibility properties are discussed together with the available experimental data.
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Affiliation(s)
- Marco Zoli
- School of Science and Technology, University of Camerino, 62032, Camerino, Italy.
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9
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Hillebrand M, Kalosakas G, Bishop AR, Skokos C. Bubble lifetimes in DNA gene promoters and their mutations affecting transcription. J Chem Phys 2021; 155:095101. [PMID: 34496591 DOI: 10.1063/5.0060335] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Relative lifetimes of inherent double stranded DNA openings with lengths up to ten base pairs are presented for different gene promoters and corresponding mutants that either increase or decrease transcriptional activity in the framework of the Peyrard-Bishop-Dauxois model. Extensive microcanonical simulations are used with energies corresponding to physiological temperature. The bubble lifetime profiles along the DNA sequences demonstrate a significant reduction of the average lifetime at the mutation sites when the mutated promoter decreases transcription, while a corresponding enhancement of the bubble lifetime is observed in the case of mutations leading to increased transcription. The relative difference in bubble lifetimes between the mutated and wild type promoters at the position of mutation varies from 20% to more than 30% as the bubble length decreases.
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Affiliation(s)
- M Hillebrand
- Nonlinear Dynamics and Chaos Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
| | - G Kalosakas
- Department of Materials Science, University of Patras, GR-26504 Rio, Greece
| | - A R Bishop
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Ch Skokos
- Nonlinear Dynamics and Chaos Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
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10
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Caprara D, Ripanti F, Capocefalo A, Ceccarini M, Petrillo C, Postorino P. Exploiting SERS sensitivity to monitor DNA aggregation properties. Int J Biol Macromol 2020; 170:88-93. [PMID: 33358955 DOI: 10.1016/j.ijbiomac.2020.12.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/19/2020] [Accepted: 12/05/2020] [Indexed: 01/11/2023]
Abstract
In the last decades, DNA has been considered far more than the system carrying the essential genetic instructions. Indeed, because of the remarkable properties of the base-pairing specificity and thermoreversibility of the interactions, DNA plays a central role in the design of innovative architectures at the nanoscale. Here, combining complementary DNA strands with a custom-made solution of silver nanoparticles, we realize plasmonic aggregates to exploit the sensitivity of Surface Enhanced Raman Spectroscopy (SERS) for the identification/detection of the distinctive features of DNA hybridization, both in solution and on dried samples. Moreover, SERS allows monitoring the DNA aggregation process by following the temperature variation of a specific spectroscopic marker associated with the Watson-Crick hydrogen bond formation. This temperature-dependent behavior enables us to precisely reconstruct the melting profile of the selected DNA sequences by spectroscopic measurements only.
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Affiliation(s)
- Debora Caprara
- Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | | | - Angela Capocefalo
- Istituto dei Sistemi Complessi-CNR c/o Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Marina Ceccarini
- National Centre for Rare Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Caterina Petrillo
- Physics and Geology Department, University of Perugia, Via A. Pascoli, 06123 Perugia, Italy
| | - Paolo Postorino
- Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
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11
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Hillebrand M, Kalosakas G, Skokos C, Bishop AR. Distributions of bubble lifetimes and bubble lengths in DNA. Phys Rev E 2020; 102:062114. [PMID: 33465959 DOI: 10.1103/physreve.102.062114] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/18/2020] [Indexed: 01/05/2023]
Abstract
We investigate the distribution of bubble lifetimes and bubble lengths in DNA at physiological temperature, by performing extensive molecular dynamics simulations with the Peyrard-Bishop-Dauxois (PBD) model, as well as an extended version (ePBD) having a sequence-dependent stacking interaction, emphasizing the effect of the sequences' guanine-cytosine (GC)/adenine-thymine (AT) content on these distributions. For both models we find that base pair-dependent (GC vs AT) thresholds for considering complementary nucleotides to be separated are able to reproduce the observed dependence of the melting temperature on the GC content of the DNA sequence. Using these thresholds for base pair openings, we obtain bubble lifetime distributions for bubbles of lengths up to ten base pairs as the GC content of the sequences is varied, which are accurately fitted with stretched exponential functions. We find that for both models the average bubble lifetime decreases with increasing either the bubble length or the GC content. In addition, the obtained bubble length distributions are also fitted by appropriate stretched exponential functions and our results show that short bubbles have similar likelihoods for any GC content, but longer ones are substantially more likely to occur in AT-rich sequences. We also show that the ePBD model permits more, longer-lived, bubbles than the PBD system.
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Affiliation(s)
- M Hillebrand
- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
| | - G Kalosakas
- Department of Materials Science, University of Patras, GR-26504 Rio, Greece
| | - Ch Skokos
- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
| | - A R Bishop
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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12
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Gabriele VR, Shvonski A, Hoffman CS, Giersig M, Herczynski A, Naughton MJ, Kempa K. Towards spectrally selective catastrophic response. Phys Rev E 2020; 101:062415. [PMID: 32688591 DOI: 10.1103/physreve.101.062415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/28/2020] [Indexed: 11/07/2022]
Abstract
We study the large-amplitude response of classical molecules to electromagnetic radiation, showing the universality of the transition from linear to nonlinear response and breakup at sufficiently large amplitudes. We demonstrate that a range of models, from the simple harmonic oscillator to the successful Peyrard-Bishop-Dauxois type models of DNA, which include realistic effects of the environment (including damping and dephasing due to thermal fluctuations), lead to characteristic universal behavior: formation of domains of dissociation in driving force amplitude-frequency space, characterized by the presence of local boundary minima. We demonstrate that by simply following the progression of the resonance maxima in this space, while gradually increasing intensity of the radiation, one must necessarily arrive at one of these minima, i.e., a point where the ultrahigh spectral selectivity is retained. We show that this universal property, applicable to other oscillatory systems, is a consequence of the fact that these models belong to the fold catastrophe universality class of Thom's catastrophe theory. This in turn implies that for most biostructures, including DNA, high spectral sensitivity near the onset of the denaturation processes can be expected. Such spectrally selective molecular denaturation could find important applications in biology and medicine.
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Affiliation(s)
- V R Gabriele
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - A Shvonski
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - C S Hoffman
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - M Giersig
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany.,International Academy of Optoelectronics at Zhaoqing, South China Normal University, 526238 Guangdong, People's Republic of China
| | - A Herczynski
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - M J Naughton
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - K Kempa
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
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13
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Chetverikov AP, Ebeling W, Lakhno VD, Velarde MG. Discrete-breather-assisted charge transport along DNA-like molecular wires. Phys Rev E 2019; 100:052203. [PMID: 31869988 DOI: 10.1103/physreve.100.052203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Indexed: 06/10/2023]
Abstract
Mobile discrete breathers (MDBs) are here suggested as localized excitations underlying the trapping and transport of charged particles (electron or hole) along a DNA-like molecular wire with anchored ends such as attached to two electrodes. For illustration the Peyrard-Bishop-Dauxois-Holstein (PBDH) model is used. MDBs are excited by imposing appropriate disturbances to velocities or space positions of adjacent nucleotide pairs or lattice units of the wire. They can be directed either towards or away from the wire hence transverse to it. Numerical computer simulations show that a rather stable quasiparticle MDB + electron is possible when just a few of the nucleotide pairs near one of the fixed ends of the wire are excited. For the process to be effective, the charge, e.g., the electron, must be initially placed around the disturbed region of the molecule. Once the MDB + electron quasiparticle is formed it may be transported to quite a long distance up to ca. 60-70 nm in real space. Our findings show that such process does not demand intervention of an externally applied electric field and hence it may be considered as alternative to the polaron transport process.
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Affiliation(s)
- A P Chetverikov
- Faculty of Physics, Saratov National Research State University, Astrakhanskaya, 83, Saratov-410012, Russia
- Institute of Mathematical Problems of Biology-Branch of Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Professor Vitkevich St., 1, Pushchino-142290, Moscow Region, Russia
| | - W Ebeling
- Institut für Physik, Humboldt Universität Berlin, Newtonstrasse 15, Berlin-12489, Germany
| | - V D Lakhno
- Institute of Mathematical Problems of Biology-Branch of Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Professor Vitkevich St., 1, Pushchino-142290, Moscow Region, Russia
| | - M G Velarde
- Instituto Pluridisciplinar, Universidad Complutense, Paseo Juan XXIII, 1, Madrid-28040, Spain
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14
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Hillebrand M, Kalosakas G, Schwellnus A, Skokos C. Heterogeneity and chaos in the Peyrard-Bishop-Dauxois DNA model. Phys Rev E 2019; 99:022213. [PMID: 30934325 DOI: 10.1103/physreve.99.022213] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Indexed: 06/09/2023]
Abstract
We discuss the effect of heterogeneity on the chaotic properties of the Peyrard-Bishop-Dauxois nonlinear model of DNA. Results are presented for the maximum Lyapunov exponent and the deviation vector distribution. Different compositions of adenine-thymine (AT) and guanine-cytosine (GC) base pairs are examined for various energies up to the melting point of the corresponding sequence. We also consider the effect of the alternation index, which measures the heterogeneity of the DNA chain through the number of alternations between different types (AT or GC) of base pairs, on the chaotic behavior of the system. Biological gene promoter sequences have been also investigated, showing no distinct behavior of the maximum Lyapunov exponent.
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Affiliation(s)
- M Hillebrand
- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
| | - G Kalosakas
- Department of Materials Science, University of Patras, GR-26504 Rio, Greece
| | - A Schwellnus
- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
| | - Ch Skokos
- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, South Africa
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, D-01187 Dresden, Germany
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15
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Mishra A, Siwach P, Misra P, Jayaram B, Bansal M, Olson WK, Thayer KM, Beveridge DL. Toward a Universal Structural and Energetic Model for Prokaryotic Promoters. Biophys J 2018; 115:1180-1189. [PMID: 30172386 DOI: 10.1016/j.bpj.2018.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/28/2018] [Accepted: 08/02/2018] [Indexed: 01/04/2023] Open
Abstract
With almost no consensus promoter sequence in prokaryotes, recruitment of RNA polymerase (RNAP) to precise transcriptional start sites (TSSs) has remained an unsolved puzzle. Uncovering the underlying mechanism is critical for understanding the principle of gene regulation. We attempted to search the hidden code in ∼16,500 promoters of 12 prokaryotes representing two kingdoms in their structure and energetics. Twenty-eight fundamental parameters of DNA structure including backbone angles, basepair axis, and interbasepair and intrabasepair parameters were used, and information was extracted from x-ray crystallography data. Three parameters (solvation energy, hydrogen-bond energy, and stacking energy) were selected for creating energetics profiles using in-house programs. DNA of promoter regions was found to be inherently designed to undergo a change in every parameter undertaken for the study, in all prokaryotes. The change starts from some distance upstream of TSSs and continues past some distance from TSS, hence giving a signature state to promoter regions. These signature states might be the universal hidden codes recognized by RNAP. This observation was reiterated when randomly selected promoter sequences (with little sequence conservation) were subjected to structure generation; all developed into very similar three-dimensional structures quite distinct from those of conventional B-DNA and coding sequences. Fine structural details at important motifs (viz. -11, -35, and -75 positions relative to TSS) of promoters reveal novel to our knowledge and pointed insights for RNAP interaction at these locations; it could be correlated with how some particular structural changes at the -11 region may allow insertion of RNAP amino acids in interbasepair space as well as facilitate the flipping out of bases from the DNA duplex.
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Affiliation(s)
- Akhilesh Mishra
- Supercomputing Facility for Bioinformatics & Computational Biology; Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, India
| | - Priyanka Siwach
- Supercomputing Facility for Bioinformatics & Computational Biology; Department of Biotechnology, Chaudhary Devi Lal University, Sirsa, Haryana, India
| | - Pallavi Misra
- Supercomputing Facility for Bioinformatics & Computational Biology
| | - Bhyravabhotla Jayaram
- Supercomputing Facility for Bioinformatics & Computational Biology; Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, India; Department of Chemistry, Indian Institute of Technology, Delhi, India.
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Wilma K Olson
- Department of Chemistry & Chemical Biology and BioMaPS Institute for Quantitative Biology, Rutgers, Piscataway, New Jersey
| | - Kelly M Thayer
- Department of Chemistry, Vassar College, Poughkeepsie, New York
| | - David L Beveridge
- Departments of Chemistry, Molecular Biology, and Biochemistry and Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
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16
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Sanstead PJ, Tokmakoff A. Direct Observation of Activated Kinetics and Downhill Dynamics in DNA Dehybridization. J Phys Chem B 2018; 122:3088-3100. [PMID: 29504399 DOI: 10.1021/acs.jpcb.8b01445] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We have studied two model DNA oligonucleotide sequences that display contrasting degrees of heterogeneous melting using an optical temperature jump to trigger dehybridization and a nonlinear infrared (IR) spectroscopy probe to track the response of the helix ensemble. This approach offers base-sensitive structural insight through the unique vibrational fingerprint characteristic of each nucleobase as well as time resolution capable of following unfolding across nanoseconds to milliseconds. We observe predissociation unzipping of the helical termini, loss of final dimer contacts, and rehybridization of the dissociated strands all in a single measurement. Complete dissociation of the dimer is found to be well described by Arrhenius kinetics for both sequences, with dissociation barriers in the range of 160-190 kJ/mol. A sequence with terminal adenine-thymine (AT) base pairs and a guanine-cytosine core returns a large-amplitude fast response ranging from 70 to 170 ns, originating only from the AT base pairs. Variable temperature jump ( T-jump) experiments in which the final temperature ( Tf) is fixed and the initial temperature ( Ti) is varied such that different starting ensembles all evolve on the same final free-energy surface were employed to explore the features of the underlying potential that dictates hybridization. These experiments reveal that the unzipping of the AT termini is an essentially barrierless process and that both activated and downhill events are necessary to describe the dehybridization mechanism. Although our results are largely consistent with the classic nucleation-zipper picture, new insights regarding the nature of base pair zippering refine the mechanistic details of the fastest DNA hybridization dynamics.
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Affiliation(s)
- Paul J Sanstead
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute , The University of Chicago , 929 East 57th Street , Chicago , Illinois 60637 , United States
| | - Andrei Tokmakoff
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute , The University of Chicago , 929 East 57th Street , Chicago , Illinois 60637 , United States
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17
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Drobotenko MI, Dzhimak SS, Svidlov AA, Basov AA, Lyasota OM, Baryshev MG. A Mathematical Model for Basepair Opening in a DNA Double Helix. Biophysics (Nagoya-shi) 2018. [DOI: 10.1134/s0006350918020069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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18
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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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19
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González-Jiménez M, Ramakrishnan G, Harwood T, Lapthorn AJ, Kelly SM, Ellis EM, Wynne K. Observation of coherent delocalized phonon-like modes in DNA under physiological conditions. Nat Commun 2016; 7:11799. [PMID: 27248361 PMCID: PMC4895446 DOI: 10.1038/ncomms11799] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/28/2016] [Indexed: 01/10/2023] Open
Abstract
Underdamped terahertz-frequency delocalized phonon-like modes have long been suggested to play a role in the biological function of DNA. Such phonon modes involve the collective motion of many atoms and are prerequisite to understanding the molecular nature of macroscopic conformational changes and related biochemical phenomena. Initial predictions were based on simple theoretical models of DNA. However, such models do not take into account strong interactions with the surrounding water, which is likely to cause phonon modes to be heavily damped and localized. Here we apply state-of-the-art femtosecond optical Kerr effect spectroscopy, which is currently the only technique capable of taking low-frequency (GHz to THz) vibrational spectra in solution. We are able to demonstrate that phonon modes involving the hydrogen bond network between the strands exist in DNA at physiologically relevant conditions. In addition, the dynamics of the solvating water molecules is slowed down by about a factor of 20 compared with the bulk.
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Affiliation(s)
| | | | - Thomas Harwood
- Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Adrian J. Lapthorn
- School of Chemistry, WestCHEM, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sharon M. Kelly
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, UK
| | - Elizabeth M. Ellis
- Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Klaas Wynne
- School of Chemistry, WestCHEM, University of Glasgow, Glasgow G12 8QQ, UK
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20
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Reiter-Schad M, Werner E, Tegenfeldt JO, Mehlig B, Ambjörnsson T. How nanochannel confinement affects the DNA melting transition within the Poland-Scheraga model. J Chem Phys 2015; 143:115101. [DOI: 10.1063/1.4930220] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Michaela Reiter-Schad
- Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE-223 62 Lund, Sweden
| | - Erik Werner
- Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Göteborg, Sweden
| | - Jonas O. Tegenfeldt
- Division of Solid State Physics, Department of Physics and NanoLund, Lund University, Box 118, SE-221 00 Lund, Sweden
| | - Bernhard Mehlig
- Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Göteborg, Sweden
| | - Tobias Ambjörnsson
- Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE-223 62 Lund, Sweden
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21
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Zrimec J, Lapanje A. Fast Prediction of DNA Melting Bubbles Using DNA Thermodynamic Stability. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2015; 12:1137-1145. [PMID: 26451825 DOI: 10.1109/tcbb.2015.2396057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
DNA melting bubbles are the basis of many DNA-protein interactions, such as those in regulatory DNA regions driving gene expression, DNA replication and bacterial horizontal gene transfer. Bubble formation is affected by DNA duplex stability and thermally induced duplex destabilization (TIDD). Although prediction of duplex stability with the nearest neighbor (NN) method is much faster than prediction of TIDD with the Peyrard-Bishop-Dauxois (PBD) model, PBD predicted TIDD defines regulatory DNA regions with higher accuracy and detail. Here, we considered that PBD predicted TIDD is inherently related to the intrinsic duplex stabilities of destabilization regions. We show by regression modeling that NN duplex stabilities can be used to predict TIDD almost as accurately as is predicted with PBD. Predicted TIDD is in fact ascribed to non-linear transformation of NN duplex stabilities in destabilization regions as well as effects of neighboring regions relative to destabilization size. Since the prediction time of our models is over six orders of magnitude shorter than that of PBD, the models present an accessible tool for researchers. TIDD can be predicted on our webserver at http://tidd.immt.eu.
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22
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Unravelling the Role of the F55 Regulator in the Transition from Lysogeny to UV Induction of Sulfolobus Spindle-Shaped Virus 1. J Virol 2015; 89:6453-61. [PMID: 25878101 DOI: 10.1128/jvi.00363-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/03/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Sulfolobus spindle-shaped virus 1 represents a model for studying virus-host interaction in harsh environments, and it is so far the only member of the family Fuselloviridae that shows a UV-inducible life cycle. Although the virus has been extensively studied, mechanisms underpinning the maintenance of lysogeny as well as those regulating the UV induction have received little attention. Recently, a novel SSV1 transcription factor, F55, was identified. This factor was able to bind in vitro to several sequences derived from the early and UV-inducible promoters of the SSV1 genome. The location of these binding sites together with the differential affinity of F55 for these sequences led to the hypothesis that this protein might be involved in the maintenance of the SSV1 lysogeny. Here, we report an in vivo survey of the molecular events occurring at the UV-inducible region of the SSV1 genome, with a focus on the binding profile of F55 before and after the UV irradiation. The binding of F55 to the target promoters correlates with transcription repression, whereas its dissociation is paralleled by transcription activation. Therefore, we propose that F55 acts as a molecular switch for the transcriptional regulation of the early viral genes. IMPORTANCE Functional genomic studies of SSV1 proteins have been hindered by the lack of similarity with other characterized proteins. As a result, few insights into their in vivo roles have been gained throughout the last 3 decades. Here, we report the first in vivo investigation of an SSV1 transcription regulator, F55, that plays a key role in the transition from the lysogenic to the induced state of SSV1. We show that F55 regulates the expression of the UV-inducible as well as the early genes. Moreover, the differential affinity of this transcription factor for these targets allows a fine-tuned and temporal coordinated regulation of transcription of viral genes.
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23
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A statistical thermodynamic model for investigating the stability of DNA sequences from oligonucleotides to genomes. Biophys J 2015; 106:2465-73. [PMID: 24896126 DOI: 10.1016/j.bpj.2014.04.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 03/20/2014] [Accepted: 04/17/2014] [Indexed: 12/12/2022] Open
Abstract
We describe the development and testing of a simple statistical mechanics methodology for duplex DNA applicable to sequences of any composition and extensible to genomes. The microstates of a DNA sequence are modeled in terms of blocks of basepairs that are assumed to be fully closed (paired) or open. This approach generates an ensemble of bubblelike microstates that are used to calculate the corresponding partition function. The energies of the microstates are calculated as additive contributions from hydrogen bonding, basepair stacking, and solvation terms parameterized from a comprehensive series of molecular dynamics simulations including solvent and ions. Thermodynamic properties and nucleotide stability constants for DNA sequences follow directly from the partition function. The methodology was tested by comparing computed free energies per basepair with the experimental melting temperatures of 60 oligonucleotides, yielding a correlation coefficient of -0.96. The thermodynamic stability of genic/nongenic regions was tested in terms of nucleotide stability constants versus sequence for the Escherichia coli K-12 genome. It showed clear differentiation of the genes from promoters and captures genic regions with a sensitivity of 0.94. The statistical thermodynamic model presented here provides a seemingly new handle on the challenging problem of interpreting genomic sequences.
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24
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Mendonca A, Chang EH, Liu W, Yuan C. Hydroxymethylation of DNA influences nucleosomal conformation and stability in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1323-9. [DOI: 10.1016/j.bbagrm.2014.09.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 09/04/2014] [Accepted: 09/08/2014] [Indexed: 12/18/2022]
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25
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Mesoscopic model and free energy landscape for protein-DNA binding sites: analysis of cyanobacterial promoters. PLoS Comput Biol 2014; 10:e1003835. [PMID: 25275384 PMCID: PMC4183373 DOI: 10.1371/journal.pcbi.1003835] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/26/2014] [Indexed: 01/23/2023] Open
Abstract
The identification of protein binding sites in promoter sequences is a key problem to understand and control regulation in biochemistry and biotechnological processes. We use a computational method to analyze promoters from a given genome. Our approach is based on a physical model at the mesoscopic level of protein-DNA interaction based on the influence of DNA local conformation on the dynamics of a general particle along the chain. Following the proposed model, the joined dynamics of the protein particle and the DNA portion of interest, only characterized by its base pair sequence, is simulated. The simulation output is analyzed by generating and analyzing the Free Energy Landscape of the system. In order to prove the capacity of prediction of our computational method we have analyzed nine promoters of Anabaena PCC 7120. We are able to identify the transcription starting site of each of the promoters as the most populated macrostate in the dynamics. The developed procedure allows also to characterize promoter macrostates in terms of thermo-statistical magnitudes (free energy and entropy), with valuable biological implications. Our results agree with independent previous experimental results. Thus, our methods appear as a powerful complementary tool for identifying protein binding sites in promoter sequences. Binding of specific proteins to particular sites in the DNA sequence is a fundamental issue for gene regulation in molecular biology and genetic engineering. A deep understanding of cell physiology requires the analysis of a plethora of genes involving characterization of their promoter architectures that determine their regulation and gene transcription. In order to locate the promoter elements of a given gene, experimental determination of its transcription start site (TSS) is required. This is an expensive, time-consuming task that, depending on our requirements, could be simplified using computational analysis as a first approach. Nevertheless, most computational methods lack a physical basis on the protein-DNA interaction mechanism. We adopt here this strategy, by using a simple model for protein-DNA interaction to find TSS in a bunch of cyanobacteria promoters. We make use of physical tools to characterize these TSS and to relate them with biological properties as the relative strength of the promoter. Our study shows how a model based on a coarse-grained description of a biomolecule can give valuable insight on its biological function.
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26
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Meyer S, Beslon G. Torsion-mediated interaction between adjacent genes. PLoS Comput Biol 2014; 10:e1003785. [PMID: 25188032 PMCID: PMC4154641 DOI: 10.1371/journal.pcbi.1003785] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 06/26/2014] [Indexed: 11/17/2022] Open
Abstract
DNA torsional stress is generated by virtually all biomolecular processes involving the double helix, in particular transcription where a significant level of stress propagates over several kilobases. If another promoter is located in this range, this stress may strongly modify its opening properties, and hence facilitate or hinder its transcription. This mechanism implies that transcribed genes distant of a few kilobases are not independent, but coupled by torsional stress, an effect for which we propose the first quantitative and systematic model. In contrast to previously proposed mechanisms of transcriptional interference, the suggested coupling is not mediated by the transcription machineries, but results from the universal mechanical features of the double-helix. The model shows that the effect likely affects prokaryotes as well as eukaryotes, but with different consequences owing to their different basal levels of torsion. It also depends crucially on the relative orientation of the genes, enhancing the expression of eukaryotic divergent pairs while reducing that of prokaryotic convergent ones. To test the in vivo influence of the torsional coupling, we analyze the expression of isolated gene pairs in the Drosophila melanogaster genome. Their orientation and distance dependence is fully consistent with the model, suggesting that torsional gene coupling may constitute a widespread mechanism of (co)regulation in eukaryotes.
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Affiliation(s)
- Sam Meyer
- Université de Lyon, INSA Lyon, INRIA, LIRIS, CNRS UMR5205, Lyon, France
| | - Guillaume Beslon
- Université de Lyon, INSA Lyon, INRIA, LIRIS, CNRS UMR5205, Lyon, France
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27
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Zoli M. Twist versus nonlinear stacking in short DNA molecules. J Theor Biol 2014; 354:95-104. [DOI: 10.1016/j.jtbi.2014.03.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/02/2014] [Accepted: 03/19/2014] [Indexed: 10/25/2022]
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28
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Sedighi A, Li PCH, Pekcevik IC, Gates BD. A proposed mechanism of the influence of gold nanoparticles on DNA hybridization. ACS NANO 2014; 8:6765-6777. [PMID: 24965286 DOI: 10.1021/nn500790m] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A combination of gold nanoparticles (AuNPs) and nucleic acids has been used in biosensing applications. However, there is a poor fundamental understanding of how gold nanoparticle surfaces influence the DNA hybridization process. Here, we measured the rate constants of the hybridization and dehybridization of DNA on gold nanoparticle surfaces to enable the determination of activation parameters using transition state theory. We show that the target bases need to be detached from the gold nanoparticle surfaces before zipping. This causes a shift of the rate-limiting step of hybridization to the mismatch-sensitive zipping step. Furthermore, our results propose that the binding of gold nanoparticles to the single-stranded DNA segments (commonly known as bubbles) in the duplex DNA stabilizes the bubbles and accelerates the dehybridization process. We employ the proposed mechanism of DNA hybridization/dehybridization to explain the ability of 5 nm diameter gold nanoparticles to help discriminate between single base-pair mismatched DNA molecules when performed in a NanoBioArray chip. The mechanistic insight into the DNA-gold nanoparticle hybridization/dehybridization process should lead to the development of new biosensors.
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Affiliation(s)
- Abootaleb Sedighi
- Department of Chemistry, Simon Fraser University , Burnaby, British Columbia V5A 1S6, Canada
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29
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Abstract
The interplay between bending of the molecule axis and appearance of disruptions in circular DNA molecules, with ∼100 base pairs, is addressed. Three minicircles with different radii and almost equal contents of AT and GC pairs are investigated. The DNA sequences are modeled by a mesoscopic Hamiltonian which describes the essential interactions in the helix at the level of the base pair and incorporates twisting and bending degrees of freedom. Helix unwinding and bubble formation patterns are consistently computed by a path integral method that sums over a large number of molecule configurations compatible with the model potential. The path ensembles are determined, as a function of temperature, by minimizing the free energy of the system. Fluctuational openings appear along the helix to release the stress due to the bending of the molecule backbone. In agreement with the experimental findings, base pair disruptions are found with larger probability in the smallest minicircle of 66 bps whose bending angle is ∼6°. For this minicircle, a sizeable untwisting is obtained with the helical repeat showing a step-like increase at T = 315 K. The method can be generalized to determine the bubble probability profiles of open ends linear sequences.
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Affiliation(s)
- Marco Zoli
- School of Science and Technology - CNISM, Università di Camerino, I-62032 Camerino, Italy.
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30
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Xiong D, Liu R, Xiao F, Gao X. ProMT: effective human promoter prediction using Markov chain model based on DNA structural properties. IEEE Trans Nanobioscience 2014; 13:374-83. [PMID: 24919203 DOI: 10.1109/tnb.2014.2327586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The core promoters play significant and extensive roles for the initiation and regulation of DNA transcription. The identification of core promoters is one of the most challenging problems yet. Due to the diverse nature of core promoters, the results obtained through existing computational approaches are not satisfactory. None of them considered the potential influence on performance of predictive approach resulted by the interference between neighboring TSSs in TSS clusters. In this paper, we sufficiently considered this main factor and proposed an approach to locate potential TSS clusters according to the correlation of regional profiles of DNA and TSS clusters. On this basis, we further presented a novel computational approach (ProMT) for promoter prediction using Markov chain model and predictive TSS clusters based on structural properties of DNA. Extensive experiments demonstrated that ProMT can significantly improve the predictive performance. Therefore, considering interference between neighboring TSSs is essential for a wider range of promoter prediction.
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31
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Talukder S, Sen S, Chakraborti P, Metzler R, Banik SK, Chaudhury P. Breathing dynamics based parameter sensitivity analysis of hetero-polymeric DNA. J Chem Phys 2014; 140:125101. [PMID: 24697480 DOI: 10.1063/1.4869112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the parameter sensitivity of hetero-polymeric DNA within the purview of DNA breathing dynamics. The degree of correlation between the mean bubble size and the model parameters is estimated for this purpose for three different DNA sequences. The analysis leads us to a better understanding of the sequence dependent nature of the breathing dynamics of hetero-polymeric DNA. Out of the 14 model parameters for DNA stability in the statistical Poland-Scheraga approach, the hydrogen bond interaction ε(hb)(AT) for an AT base pair and the ring factor ξ turn out to be the most sensitive parameters. In addition, the stacking interaction ε(st)(TA-TA) for an TA-TA nearest neighbor pair of base-pairs is found to be the most sensitive one among all stacking interactions. Moreover, we also establish that the nature of stacking interaction has a deciding effect on the DNA breathing dynamics, not the number of times a particular stacking interaction appears in a sequence. We show that the sensitivity analysis can be used as an effective measure to guide a stochastic optimization technique to find the kinetic rate constants related to the dynamics as opposed to the case where the rate constants are measured using the conventional unbiased way of optimization.
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Affiliation(s)
- Srijeeta Talukder
- Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009, India
| | - Shrabani Sen
- Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009, India
| | - Prantik Chakraborti
- Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700 009, India
| | - Ralf Metzler
- Institute for Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany and Physics Department, Tampere University of Technology, FI-33101 Tampere, Finland
| | - Suman K Banik
- Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700 009, India
| | - Pinaki Chaudhury
- Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009, India
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32
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Single-molecule FRET and linear dichroism studies of DNA breathing and helicase binding at replication fork junctions. Proc Natl Acad Sci U S A 2013; 110:17320-5. [PMID: 24062430 DOI: 10.1073/pnas.1314862110] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA "breathing" is a thermally driven process in which base-paired DNA sequences transiently adopt local conformations that depart from their most stable structures. Polymerases and other proteins of genome expression require access to single-stranded DNA coding templates located in the double-stranded DNA "interior," and it is likely that fluctuations of the sugar-phosphate backbones of dsDNA that result in mechanistically useful local base pair opening reactions can be exploited by such DNA regulatory proteins. Such motions are difficult to observe in bulk measurements, both because they are infrequent and because they often occur on microsecond time scales that are not easy to access experimentally. We report single-molecule fluorescence experiments with polarized light, in which tens-of-microseconds rotational motions of internally labeled iCy3/iCy5 donor-acceptor Förster resonance energy transfer fluorophore pairs that have been rigidly inserted into the backbones of replication fork constructs are simultaneously detected using single-molecule Förster resonance energy transfer and single-molecule fluorescence-detected linear dichroism signals. Our results reveal significant local motions in the ∼100-μs range, a reasonable time scale for DNA breathing fluctuations of potential relevance for DNA-protein interactions. Moreover, we show that both the magnitudes and the relaxation times of these backbone breathing fluctuations are significantly perturbed by interactions of the fork construct with a nonprocessive, weakly binding bacteriophage T4-coded helicase hexamer initiation complex, suggesting that these motions may play a fundamental role in the initial binding, assembly, and function of the processive helicase-primase (primosome) component of the bacteriophage T4-coded DNA replication complex.
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Kanayama N, Takarada T, Fujita M, Maeda M. DNA Terminal Breathing Regulated by Metal Ions for Colloidal Logic Gates. Chemistry 2013; 19:10794-8. [DOI: 10.1002/chem.201301995] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Indexed: 02/07/2023]
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Mekler V, Severinov K. Cooperativity and interaction energy threshold effects in recognition of the -10 promoter element by bacterial RNA polymerase. Nucleic Acids Res 2013; 41:7276-85. [PMID: 23771146 PMCID: PMC3753650 DOI: 10.1093/nar/gkt541] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
RNA polymerase (RNAP) melts promoter DNA to form transcription-competent open promoter complex (RPo). Interaction of the RNAP σ subunit with non-template strand bases of a conserved -10 element (consensus sequence T-12A-11T-10A-9A-8T-7) is an important source of energy-driving localized promoter melting. Here, we used an RNAP molecular beacon assay to investigate interdependencies of RNAP interactions with -10 element nucleotides. The results reveal a strong cooperation between RNAP interactions with individual -10 element non-template strand nucleotides and indicate that recognition of the -10 element bases occurs only when free energy of the overall RNAP -10 element binding reaches a certain threshold level. The threshold-like mode of the -10 element recognition may be related to the energetic cost of attaining a conformation of the -10 element that is recognizable by RNAP. The RNAP interaction with T/A-12 base pair was found to be strongly stimulated by RNAP interactions with other -10 element bases and with promoter spacer between the -10 and -35 promoter elements. The data also indicate that unmelted -10 promoter element can impair RNAP interactions with promoter DNA upstream of the -11 position. We suggest that cooperativity and threshold effects are important factors guiding the dynamics and selectivity of RPo formation.
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Affiliation(s)
- Vladimir Mekler
- Department of Molecular Biology and Biochemistry, Waksman Institute of Microbiology Rutgers, State University of New Jersey, Piscataway, NJ 08854, USA and Institutes of Molecular Genetics and Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
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Datta S, Mukhopadhyay S. A composite method based on formal grammar and DNA structural features in detecting human polymerase II promoter region. PLoS One 2013; 8:e54843. [PMID: 23437045 PMCID: PMC3577817 DOI: 10.1371/journal.pone.0054843] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/17/2012] [Indexed: 11/25/2022] Open
Abstract
An important step in understanding gene regulation is to identify the promoter regions where the transcription factor binding takes place. Predicting a promoter region de novo has been a theoretical goal for many researchers for a long time. There exists a number of in silico methods to predict the promoter region de novo but most of these methods are still suffering from various shortcomings, a major one being the selection of appropriate features of promoter region distinguishing them from non-promoters. In this communication, we have proposed a new composite method that predicts promoter sequences based on the interrelationship between structural profiles of DNA and primary sequence elements of the promoter regions. We have shown that a Context Free Grammar (CFG) can formalize the relationships between different primary sequence features and by utilizing the CFG, we demonstrate that an efficient parser can be constructed for extracting these relationships from DNA sequences to distinguish the true promoter sequences from non-promoter sequences. Along with CFG, we have extracted the structural features of the promoter region to improve upon the efficiency of our prediction system. Extensive experiments performed on different datasets reveals that our method is effective in predicting promoter sequences on a genome-wide scale and performs satisfactorily as compared to other promoter prediction techniques.
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Affiliation(s)
- Sutapa Datta
- Department of Biophysics, Molecular Biology and Bioinformatics and Distributed Information Centre for Bioinformatics, University of Calcutta, Kolkata, West Bengal, India.
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37
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Bergues-Pupo AE, Bergues JM, Falo F. Modeling the interaction of DNA with alternating fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:022703. [PMID: 23496544 DOI: 10.1103/physreve.87.022703] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Indexed: 05/22/2023]
Abstract
We study the influence of a terahertz field on thermal properties of DNA molecules. A Peyrard-Bishop-Dauxois model with the inclusion of a solvent interaction term is considered. The terahertz field is included as a sinusoidal driven force in the equation of motion. We show how under certain field and system parameters, the melting transition and bubble formation are modified.
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Affiliation(s)
- A E Bergues-Pupo
- Departamento de Física, Universidad de Oriente, 90500 Santiago de Cuba, Cuba
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38
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Specificity and heterogeneity of terahertz radiation effect on gene expression in mouse mesenchymal stem cells. Sci Rep 2013; 3:1184. [PMID: 23378916 PMCID: PMC3560359 DOI: 10.1038/srep01184] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/14/2013] [Indexed: 12/13/2022] Open
Abstract
We report that terahertz (THz) irradiation of mouse mesenchymal stem cells (mMSCs) with a single-frequency (SF) 2.52 THz laser or pulsed broadband (centered at 10 THz) source results in irradiation specific heterogenic changes in gene expression. The THz effect depends on irradiation parameters such as the duration and type of THz source, and on the degree of stem cell differentiation. Our microarray survey and RT-PCR experiments demonstrate that prolonged broadband THz irradiation drives mMSCs toward differentiation, while 2-hour irradiation (regardless of THz sources) affects genes transcriptionally active in pluripotent stem cells. The strictly controlled experimental environment indicates minimal temperature changes and the absence of any discernable response to heat shock and cellular stress genes imply a non-thermal response. Computer simulations of the core promoters of two pluripotency markers reveal association between gene upregulation and propensity for DNA breathing. We propose that THz radiation has potential for non-contact control of cellular gene expression.
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Abstract
Modelling DNA is useful for understanding its properties better but it is also challenging because many of these properties involve hundreds of base pairs or more, or time scales which are much longer than the time scales accessible to molecular dynamics. It is therefore necessary to develop models at a mesoscale, which include enough details to describe the properties of interest, for instance the biological sequence, while staying sufficiently simple and realistic.We discuss here two examples: a dynamical model to study the mechanical denaturation of DNA, which probes the sequence on various scales, and a model for the self assembly of DNA which describes the formation of hairpins and allows us to study its kinetics.
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40
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Nowak-Lovato K, Alexandrov LB, Banisadr A, Bauer AL, Bishop AR, Usheva A, Mu F, Hong-Geller E, Rasmussen KØ, Hlavacek WS, Alexandrov BS. Binding of nucleoid-associated protein fis to DNA is regulated by DNA breathing dynamics. PLoS Comput Biol 2013; 9:e1002881. [PMID: 23341768 PMCID: PMC3547798 DOI: 10.1371/journal.pcbi.1002881] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/29/2012] [Indexed: 12/23/2022] Open
Abstract
Physicochemical properties of DNA, such as shape, affect protein-DNA recognition. However, the properties of DNA that are most relevant for predicting the binding sites of particular transcription factors (TFs) or classes of TFs have yet to be fully understood. Here, using a model that accurately captures the melting behavior and breathing dynamics (spontaneous local openings of the double helix) of double-stranded DNA, we simulated the dynamics of known binding sites of the TF and nucleoid-associated protein Fis in Escherichia coli. Our study involves simulations of breathing dynamics, analysis of large published in vitro and genomic datasets, and targeted experimental tests of our predictions. Our simulation results and available in vitro binding data indicate a strong correlation between DNA breathing dynamics and Fis binding. Indeed, we can define an average DNA breathing profile that is characteristic of Fis binding sites. This profile is significantly enriched among the identified in vivo E. coli Fis binding sites. To test our understanding of how Fis binding is influenced by DNA breathing dynamics, we designed base-pair substitutions, mismatch, and methylation modifications of DNA regions that are known to interact (or not interact) with Fis. The goal in each case was to make the local DNA breathing dynamics either closer to or farther from the breathing profile characteristic of a strong Fis binding site. For the modified DNA segments, we found that Fis-DNA binding, as assessed by gel-shift assay, changed in accordance with our expectations. We conclude that Fis binding is associated with DNA breathing dynamics, which in turn may be regulated by various nucleotide modifications. Cellular transcription factors (TFs) are proteins that regulate gene expression, and thereby cellular activity and fate, by binding to specific DNA segments. The physicochemical determinants of protein-DNA binding specificity are not completely understood. Here, we report that the propensity of transient opening and re-closing of the double helix, resulting from thermal fluctuations, aka “DNA breathing” or “DNA bubbles,” can be associated with binding affinity in the case of Fis, a well-studied nucleoid-associated protein in Escherichia coli. We found that a particular breathing profile is characteristic of high-affinity Fis binding sites and that DNA fragments known to bind Fis in vivo are statistically enriched for this profile. Furthermore, we used simulations of DNA breathing dynamics to guide design of gel-shift experiments aimed at testing the idea that local breathing influences Fis binding. As a result, we show that via nucleotide modifications but without modifying nucleotides that directly contact Fis, we were able to transform a low-affinity Fis binding site into a high-affinity site and vice versa. The nucleotide modifications were designed only based on DNA breathing simulations. Our study suggests that strong Fis-DNA binding depends on DNA breathing - a novel physicochemical characteristic that could be used for prediction and rational design of TF binding sites.
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Affiliation(s)
- Kristy Nowak-Lovato
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Ludmil B. Alexandrov
- Cancer Genome Project, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Afsheen Banisadr
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Amy L. Bauer
- X-Theoretical Design Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Alan R. Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Anny Usheva
- Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Fangping Mu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Elizabeth Hong-Geller
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Kim Ø. Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - William S. Hlavacek
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
- * E-mail: (WSH); (BSA)
| | - Boian S. Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
- * E-mail: (WSH); (BSA)
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Tapia-Rojo R, Prada-Gracia D, Mazo JJ, Falo F. Mesoscopic model for free-energy-landscape analysis of DNA sequences. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:021908. [PMID: 23005786 DOI: 10.1103/physreve.86.021908] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 07/21/2012] [Indexed: 06/01/2023]
Abstract
A mesoscopic model which allows us to identify and quantify the strength of binding sites in DNA sequences is proposed. The model is based on the Peyrard-Bishop-Dauxois model for the DNA chain coupled to a Brownian particle which explores the sequence interacting more importantly with open base pairs of the DNA chain. We apply the model to promoter sequences of different organisms. The free energy landscape obtained for these promoters shows a complex structure that is strongly connected to their biological behavior. The analysis method used is able to quantify free energy differences of sites within genome sequences.
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Affiliation(s)
- R Tapia-Rojo
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
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42
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Mechanism of homology recognition in DNA recombination from dual-molecule experiments. Mol Cell 2012; 46:616-24. [PMID: 22560720 DOI: 10.1016/j.molcel.2012.03.029] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 02/21/2012] [Accepted: 03/30/2012] [Indexed: 11/24/2022]
Abstract
In E. coli homologous recombination, a filament of RecA protein formed on DNA searches and pairs a homologous sequence within a second DNA molecule with remarkable speed and fidelity. Here, we directly probe the strength of the two-molecule interactions involved in homology search and recognition using dual-molecule manipulation, combining magnetic and optical tweezers. We find that the filament's secondary DNA-binding site interacts with a single strand of the incoming double-stranded DNA during homology sampling. Recognition requires opening of the helix and is strongly promoted by unwinding torsional stress. Recognition is achieved upon binding of both strands of the incoming dsDNA to each of two ssDNA-binding sites in the filament. The data indicate a physical picture for homology recognition in which the fidelity of the search process is governed by the distance between the DNA-binding sites.
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43
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Hernández-Lemus E, Nicasio-Collazo LA, Castañeda-Priego R. Hysteresis in pressure-driven DNA denaturation. PLoS One 2012; 7:e33789. [PMID: 22496765 PMCID: PMC3322130 DOI: 10.1371/journal.pone.0033789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 02/17/2012] [Indexed: 12/22/2022] Open
Abstract
In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.
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Affiliation(s)
- Enrique Hernández-Lemus
- Computational Genomics Department, National Institute of Genomic Medicine, México, D.F., México
- Center for Complexity Sciences, National Autonomous University of México, México, D.F., México
| | | | - Ramón Castañeda-Priego
- Division of Sciences and Engineering, University of Guanajuato, León, Guanajuato, México
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44
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Kalosakas G. Charge transport in DNA: dependence of diffusion coefficient on temperature and electron-phonon coupling constant. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:051905. [PMID: 22181442 DOI: 10.1103/physreve.84.051905] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 10/14/2011] [Indexed: 05/31/2023]
Abstract
The diffusion coefficient is calculated for a charge propagating along a double-stranded DNA, while it interacts with the nonlinear fluctuational openings of base pairs. The latter structural dynamics of DNA is described by the Peyrard-Bishop-Dauxois model [T. Dauxois, M. Peyrard, and A. R. Bishop, Phys Rev. E 47 R44 (1993)], which represents essential anharmonicities of base-pair stretchings. The dependence of the diffusion coefficient on the temperature and the electron-phonon coupling constant is presented. The diffusion coefficient decreases when either the temperature or the electron-phonon coupling increases. Analytical expressions are provided that describe the temperature dependence of the diffusion coefficient. The variation of the parameters of these expressions with the electron-phonon coupling constant is also discussed. These results quantitatively demonstrate how DNA structural nonlinear dynamics affects macroscopic charge transport properties.
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45
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Poccia N, Bianconi A. The Physics of Life and Quantum Complex Matter: A Case of Cross-Fertilization. Life (Basel) 2011; 1:3-6. [PMID: 26791661 PMCID: PMC4187125 DOI: 10.3390/life1010003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 08/31/2011] [Indexed: 12/03/2022] Open
Abstract
Progress in the science of complexity, from the Big Bang to the coming of humankind, from chemistry and biology to geosciences and medicine, and from materials engineering to energy sciences, is leading to a shift of paradigm in the physical sciences. The focus is on the understanding of the non-equilibrium process in fine tuned systems. Quantum complex materials such as high temperature superconductors and living matter are both non-equilibrium and fine tuned systems. These topics have been subbjects of scientific discussion in the Rome Symposium on the “Quantum Physics of Living Matter”.
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Affiliation(s)
- Nicola Poccia
- Department of Physics, Sapienza University of Rome, P. le A. Moro 2, 00185 Roma, Italy.
| | - Antonio Bianconi
- Department of Physics, Sapienza University of Rome, P. le A. Moro 2, 00185 Roma, Italy.
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46
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Shigaev A, Ponomarev O, Lakhno V. A new approach to microscopic modeling of a hole transfer in heteropolymer DNA. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.07.080] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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47
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Mishra H, Singh N, Misra K, Lahiri T. An ANN-GA model based promoter prediction in Arabidopsis thaliana using tilling microarray data. Bioinformation 2011; 6:240-3. [PMID: 21887014 PMCID: PMC3159145 DOI: 10.6026/97320630006240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 05/09/2011] [Indexed: 11/23/2022] Open
Abstract
Identification of promoter region is an important part of gene annotation. Identification of promoters in eukaryotes is important as promoters modulate various
metabolic functions and cellular stress responses. In this work, a novel approach utilizing intensity values of tilling microarray data for a model eukaryotic plant
Arabidopsis thaliana, was used to specify promoter region from non-promoter region. A feed-forward back propagation neural network model supported by
genetic algorithm was employed to predict the class of data with a window size of 41. A dataset comprising of 2992 data vectors representing both promoter and
non-promoter regions, chosen randomly from probe intensity vectors for whole genome of Arabidopsis thaliana generated through tilling microarray technique
was used. The classifier model shows prediction accuracy of 69.73% and 65.36% on training and validation sets, respectively. Further, a concept of distance based
class membership was used to validate reliability of classifier, which showed promising results. The study shows the usability of micro-array probe intensities to
predict the promoter regions in eukaryotic genomes.
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Affiliation(s)
- Hrishikesh Mishra
- Division of Applied Sciences and Indo-Russian Centre for Biotechnology, Indian Institute of Information Technology, Allahabad, India
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48
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Calistri E, Livi R, Buiatti M. Evolutionary trends of GC/AT distribution patterns in promoters. Mol Phylogenet Evol 2011; 60:228-35. [PMID: 21554969 DOI: 10.1016/j.ympev.2011.04.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 03/25/2011] [Accepted: 04/17/2011] [Indexed: 11/18/2022]
Abstract
Nucleotide distributions in genomes is known not to be random, showing the presence of specific motifs, long and short range correlations, periodicities, etc. Particularly, motifs are critical for the recognition by specific proteins affecting chromosome organization, transcription and DNA replication but little is known about the possible functional effects of nucleotide distributions on the conformational landscape of DNA, putatively leading to differential selective pressures throughout evolution. Promoter sequences have a fundamental role in the regulation of gene activity and a vast literature suggests that their conformational landscapes may be a critical factor in gene expression dynamics. On these grounds, with the aim of investigating the putative existence of phylogenetic patterns of promoter base distributions, we analyzed GC/AT ratios along the 1000 nucleotide sequences upstream of TSS in wide sets of promoters belonging to organisms ranging from bacteria to pluricellular eukaryotes. The data obtained showed very clear phylogenetic trends throughout evolution of promoter sequence base distributions. Particularly, in all cases either GC-rich or AT-rich monotone gradients were observed: the former being present in eukaryotes, the latter in bacteria along with strand biases. Moreover, within eukaryotes, GC-rich gradients increased in length from unicellular organisms to plants, to vertebrates and, within them, from ancestral to more recent species. Finally, results were thoroughly discussed with particular attention to the possible correlation between nucleotide distribution patterns, evolution, and the putative existence of differential selection pressures, deriving from structural and/or functional constraints, between and within prokaryotes and eukaryotes.
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Affiliation(s)
- Elisa Calistri
- Dipartimento di Biologia Evoluzionistica, Universita' degli Studi di Firenze, via Romana 19, 50125 Firenze, Italy.
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Mechanics of the IL2RA gene activation revealed by modeling and atomic force microscopy. PLoS One 2011; 6:e18811. [PMID: 21533205 PMCID: PMC3076448 DOI: 10.1371/journal.pone.0018811] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 03/16/2011] [Indexed: 01/22/2023] Open
Abstract
Transcription implies recruitment of RNA polymerase II and transcription factors (TFs) by DNA melting near transcription start site (TSS). Combining atomic force microscopy and computer modeling, we investigate the structural and dynamical properties of the IL2RA promoter and identify an intrinsically negative supercoil in the PRRII region (containing Elf-1 and HMGA1 binding sites), located upstream of a curved DNA region encompassing TSS. Conformational changes, evidenced by time-lapse studies, result in the progressive positioning of curvature apex towards the TSS, likely facilitating local DNA melting. In vitro assays confirm specific binding of the General Transcription Factors (GTFs) TBP and TFIIB over TATA-TSS position, where an inhibitory nucleosome prevented preinitiation complex (PIC) formation and uncontrolled DNA melting. These findings represent a substantial advance showing, first, that the structural properties of the IL2RA promoter are encoded in the DNA sequence and second, that during the initiation process DNA conformation is dynamic and not static.
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50
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Apostolaki A, Kalosakas G. Targets of DNA-binding proteins in bacterial promoter regions present enhanced probabilities for spontaneous thermal openings. Phys Biol 2011; 8:026006. [DOI: 10.1088/1478-3975/8/2/026006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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