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Sengupta S, Bhattacharjee SM, Mishra G. Large bubble drives circular DNA melting. Phys Chem Chem Phys 2024. [PMID: 39027987 DOI: 10.1039/d4cp01536c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
We investigate the melting transition of non-supercoiled circular DNA of different lengths, employing Brownian dynamics simulations. In the absence of supercoiling, we find that melting of circular DNA is driven by a large bubble, which agrees with the previous predictions of circular DNA melting in the presence of supercoiling. By analyzing sector-wise changes in average base-pair distance, our study reveals that the melting behavior of circular DNA closely resembles that of linear DNA. Additionally, we find a marked difference in the thermal stability of circular DNA over linear DNA at very short length scales, an effect that diminishes as the length of circular DNA increases. The stability of smaller circular DNA is linked to the occurrence of transient small bubbles, characterized by a lower probability of growth.
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Affiliation(s)
- Souradeep Sengupta
- Department of Physics, Ashoka University, Sonipat, Haryana - 131029, India.
| | | | - Garima Mishra
- Department of Physics, Ashoka University, Sonipat, Haryana - 131029, India.
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2
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Liu ZX, Zhang S, Zhu HZ, Chen ZH, Yang Y, Li LQ, Lei Y, Liu Y, Li DY, Sun A, Li CP, Tan SQ, Wang GL, Shen JY, Jin S, Gao C, Liu JJG. Hydrolytic endonucleolytic ribozyme (HYER) is programmable for sequence-specific DNA cleavage. Science 2024; 383:eadh4859. [PMID: 38301022 DOI: 10.1126/science.adh4859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 12/27/2023] [Indexed: 02/03/2024]
Abstract
Ribozymes are catalytic RNAs with diverse functions including self-splicing and polymerization. This work aims to discover natural ribozymes that behave as hydrolytic and sequence-specific DNA endonucleases, which could be repurposed as DNA manipulation tools. Focused on bacterial group II-C introns, we found that many systems without intron-encoded protein propagate multiple copies in their resident genomes. These introns, named HYdrolytic Endonucleolytic Ribozymes (HYERs), cleaved RNA, single-stranded DNA, bubbled double-stranded DNA (dsDNA), and plasmids in vitro. HYER1 generated dsDNA breaks in the mammalian genome. Cryo-electron microscopy analysis revealed a homodimer structure for HYER1, where each monomer contains a Mg2+-dependent hydrolysis pocket and captures DNA complementary to the target recognition site (TRS). Rational designs including TRS extension, recruiting sequence insertion, and heterodimerization yielded engineered HYERs showing improved specificity and flexibility for DNA manipulation.
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Affiliation(s)
- Zi-Xian Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shouyue Zhang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Han-Zhou Zhu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhi-Hang Chen
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yun Yang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Long-Qi Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Lei
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yun Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dan-Yuan Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ao Sun
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Cheng-Ping Li
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shun-Qing Tan
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Gao-Li Wang
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jie-Yi Shen
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shuai Jin
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Caixia Gao
- New Cornerstone Science Laboratory, Center for Genome Editing, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jun-Jie Gogo Liu
- Beijing Advanced Innovation Center for Structural Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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3
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Biere N, Kreft D, Walhorn V, Schwarzbich S, Glaser T, Anselmetti D. Dinuclear complex-induced DNA melting. J Nanobiotechnology 2023; 21:26. [PMID: 36691056 PMCID: PMC9869567 DOI: 10.1186/s12951-023-01784-8] [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: 09/16/2022] [Accepted: 01/15/2023] [Indexed: 01/24/2023] Open
Abstract
Dinuclear copper complexes have been designed for molecular recognition in order to selectively bind to two neighboring phosphate moieties in the backbone of double strand DNA. Associated biophysical, biochemical and cytotoxic effects on DNA were investigated in previous works, where atomic force microscopy (AFM) in ambient conditions turned out to be a particular valuable asset, since the complexes influence the macromechanical properties and configurations of the strands. To investigate and scrutinize these effects in more depth from a structural point of view, cutting-edge preparation methods and scanning force microscopy under ultra-high vacuum (UHV) conditions were employed to yield submolecular resolution images. DNA strand mechanics and interactions could be resolved on the single base pair level, including the amplified formation of melting bubbles. Even the interaction of singular complex molecules could be observed. To better assess the results, the appearance of treated DNA is also compared to the behavior of untreated DNA in UHV on different substrates. Finally, we present data from a statistical simulation reasoning about the nanomechanics of strand dissociation. This sort of quantitative experimental insights paralleled by statistical simulations impressively shade light on the rationale for strand dissociations of this novel DNA interaction process, that is an important nanomechanistic key and novel approach for the development of new chemotherapeutic agents.
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Affiliation(s)
- Niklas Biere
- grid.7491.b0000 0001 0944 9128Experimental Biophysics & Applied Nanoscience, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Dennis Kreft
- grid.7491.b0000 0001 0944 9128Experimental Biophysics & Applied Nanoscience, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Volker Walhorn
- grid.7491.b0000 0001 0944 9128Experimental Biophysics & Applied Nanoscience, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Sabrina Schwarzbich
- grid.7491.b0000 0001 0944 9128Lehrstuhl für Anorganische Chemie I, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany
| | - Thorsten Glaser
- grid.7491.b0000 0001 0944 9128Lehrstuhl für Anorganische Chemie I, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany
| | - Dario Anselmetti
- grid.7491.b0000 0001 0944 9128Experimental Biophysics & Applied Nanoscience, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
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4
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Majumdar D. Elasticity of a DNA chain dotted with bubbles under force. Phys Rev E 2021; 103:052412. [PMID: 34134228 DOI: 10.1103/physreve.103.052412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 05/04/2021] [Indexed: 11/07/2022]
Abstract
The flexibility and the extension along the direction of the force are shown to be related to the bubble number fluctuation and the average number of bubbles, respectively, when the strands of the DNA are subjected to a force along the same direction, here called a stretching force. The force-temperature phase diagram shows the existence of a tricritical point, where the first-order force-induced zipping transition becomes continuous. On the other hand, when the forces are being applied in opposite directions, here called an unzipping force, the transition remains first order, with the possibility of vanishing of the low-temperature reentrant phase for a semiflexible DNA. Moreover, we found that the bulk elasticity changes only if an external force penetrates the bound phase and affects the bubble states.
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Affiliation(s)
- Debjyoti Majumdar
- Institute of Physics, Bhubaneswar, Odisha 751005, India and Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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5
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Prokhorov VV, Barinov NA, Prusakov KA, Dubrovin EV, Frank-Kamenetskii MD, Klinov DV. Anomalous Laterally Stressed Kinetically Trapped DNA Surface Conformations. NANO-MICRO LETTERS 2021; 13:130. [PMID: 34138333 PMCID: PMC8141082 DOI: 10.1007/s40820-021-00626-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
DNA kinking is inevitable for the highly anisotropic 1D-1D electrostatic interaction with the one-dimensionally periodically charged surface. The double helical structure of the DNA kinetically trapped on positively charged monomolecular films comprising the lamellar templates is strongly laterally stressed and extremely perturbed at the nanometer scale. The DNA kinetic trapping is not a smooth 3D-> 2D conformational flattening but is a complex nonlinear in-plane mechanical response (bending, tensile and unzipping) driven by the physics beyond the scope of the applicability of the linear worm-like chain approximation. Up to now, the DNA molecule adsorbed on a surface was believed to always preserve its native structure. This belief implies a negligible contribution of lateral surface forces during and after DNA adsorption although their impact has never been elucidated. High-resolution atomic force microscopy was used to observe that stiff DNA molecules kinetically trapped on monomolecular films comprising one-dimensional periodically charged lamellar templates as a single layer or as a sublayer are oversaturated by sharp discontinuous kinks and can also be locally melted and supercoiled. We argue that kink/anti-kink pairs are induced by an overcritical lateral bending stress (> 30 pNnm) inevitable for the highly anisotropic 1D-1D electrostatic interaction of DNA and underlying rows of positive surface charges. In addition, the unexpected kink-inducing mechanical instability in the shape of the template-directed DNA confined between the positively charged lamellar sides is observed indicating the strong impact of helicity. The previously reported anomalously low values of the persistence length of the surface-adsorbed DNA are explained by the impact of the surface-induced low-scale bending. The sites of the local melting and supercoiling are convincingly introduced as other lateral stress-induced structural DNA anomalies by establishing a link with DNA high-force mechanics. The results open up the study in the completely unexplored area of the principally anomalous kinetically trapped DNA surface conformations in which the DNA local mechanical response to the surface-induced spatially modulated lateral electrostatic stress is essentially nonlinear. The underlying rich and complex in-plane nonlinear physics acts at the nanoscale beyond the scope of applicability of the worm-like chain approximation.
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Affiliation(s)
- Valery V Prokhorov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow, 119435, Russian Federation.
- A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Leninsky prospect 31, Moscow, 199071, Russian Federation.
| | - Nikolay A Barinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow, 119435, Russian Federation
| | - Kirill A Prusakov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow, 119435, Russian Federation
- Moscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudny, 141700, Moscow, Russian Federation
| | - Evgeniy V Dubrovin
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow, 119435, Russian Federation
- Lomonosov Moscow State University, Leninskie gory, 1-2, Moscow, 119991, Russian Federation
| | | | - Dmitry V Klinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow, 119435, Russian Federation.
- Moscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudny, 141700, Moscow, Russian Federation.
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6
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Xu W, Dunlap D, Finzi L. Energetics of twisted DNA topologies. Biophys J 2021; 120:3242-3252. [PMID: 33974883 DOI: 10.1016/j.bpj.2021.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 03/30/2021] [Accepted: 05/05/2021] [Indexed: 11/30/2022] Open
Abstract
Our goal is to review the main theoretical models used to calculate free energy changes associated with common, torsion-induced conformational changes in DNA and provide the resulting equations hoping to facilitate quantitative analysis of both in vitro and in vivo studies. This review begins with a summary of work regarding the energy change of the negative supercoiling-induced B- to L-DNA transition, followed by a discussion of the energetics associated with the transition to Z-form DNA. Finally, it describes the energy changes associated with the formation of DNA curls and plectonemes, which can regulate DNA-protein interactions and promote cross talk between distant DNA elements, respectively. The salient formulas and parameters for each scenario are summarized in table format to facilitate comparison and provide a concise, user-friendly resource.
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Affiliation(s)
- Wenxuan Xu
- Emory University, Department of Physics, Atlanta, Georgia
| | - David Dunlap
- Emory University, Department of Physics, Atlanta, Georgia
| | - Laura Finzi
- Emory University, Department of Physics, Atlanta, Georgia.
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7
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Jiang J. Non-monotonic Effects of Intrinsic Stiffness and Concentration of Polyelectrolytes on the Electro-Sorption. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02472] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jian Jiang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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8
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Ott K, Martini L, Lipfert J, Gerland U. Dynamics of the Buckling Transition in Double-Stranded DNA and RNA. Biophys J 2020; 118:1690-1701. [PMID: 32367807 PMCID: PMC7136337 DOI: 10.1016/j.bpj.2020.01.049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/11/2019] [Accepted: 01/07/2020] [Indexed: 10/24/2022] Open
Abstract
DNA under torsional strain undergoes a buckling transition that is the fundamental step in plectoneme nucleation and supercoil dynamics, which are critical for the processing of genomic information. Despite its importance, quantitative models of the buckling transition, in particular to also explain the surprising two-orders-of-magnitude difference between the buckling times for RNA and DNA revealed by single-molecule tweezers experiments, are currently lacking. Additionally, little is known about the configurations of the DNA during the buckling transition because they are not directly observable experimentally. Here, we use a discrete worm-like chain model and Brownian dynamics to simulate the DNA/RNA buckling transition. Our simulations are in good agreement with experimentally determined parameters of the buckling transition. The simulations show that the buckling time strongly and exponentially depends on the bending stiffness, which accounts for more than half the measured difference between DNA and RNA. Analyzing the microscopic conformations of the chain revealed by our simulations, we find clear evidence for a solenoid-shaped transition state and a curl intermediate. The curl intermediate features a single loop and becomes increasingly populated at low forces. Taken together, the simulations suggest that the worm-like chain model can account semiquantitatively for the buckling dynamics of both DNA and RNA.
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Affiliation(s)
- Katharina Ott
- Physics of Complex Biosystems, Physics Department, Technical University of Munich, Garching, Germany
| | - Linda Martini
- Physics of Complex Biosystems, Physics Department, Technical University of Munich, Garching, Germany
| | - Jan Lipfert
- Department of Physics and Center for NanoScience, LMU Munich, Munich, Germany
| | - Ulrich Gerland
- Physics of Complex Biosystems, Physics Department, Technical University of Munich, Garching, Germany.
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9
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Zoli M. First-passage probability: a test for DNA Hamiltonian parameters. Phys Chem Chem Phys 2020; 22:26901-26909. [DOI: 10.1039/d0cp04046k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A method is developed to chose the set of input parameters for DNA mesoscopic Hamiltonian models.
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Affiliation(s)
- Marco Zoli
- School of Science and Technology
- University of Camerino
- I-62032 Camerino
- Italy
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10
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Gu Z, Song W, Chen SH, Li B, Li W, Zhou R. Defect-assisted protein HP35 denaturation on graphene. NANOSCALE 2019; 11:19362-19369. [PMID: 31099814 DOI: 10.1039/c9nr01143a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Structural defects in nanomaterials can alter their physical and chemical properties including magnetization, electronic and thermal conductivities, light absorption, and emission capabilities. Here, we investigated the potential impact of these defects on their biological effects through molecular dynamics simulations. By modeling the interaction between a graphene nanosheet and a widely used model protein, the chicken villin headpiece subdomain (HP35), we observed severe protein denaturation upon contact with defective graphene, while the protein remained intact on ideal graphene. The enhanced toxicity of defective graphene was due to the stronger attraction of the surface residues of HP35 from the defect edges (represented by carboxyl groups in our simulations) than from the ideal graphene. Upon binding to defective graphene, the contacting residues were restrained near the defective sites, which acted as "anchors" for the adsorbed protein. The "anchors" subsequently caused the protein to expose its aromatic and hydrophobic core residues to the graphene surface, via strong π-π stacking and hydrophobic interactions, thus leading to the unfolding of the protein. These findings not only highlight the importance of defects in nanomaterials' impact on biological systems, but also provide insights into fine-tuning the potential biological properties of nanomaterials through defect engineering.
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Affiliation(s)
- Zonglin Gu
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
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11
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Cencini M, Pigolotti S. Energetic funnel facilitates facilitated diffusion. Nucleic Acids Res 2019; 46:558-567. [PMID: 29216364 PMCID: PMC5778461 DOI: 10.1093/nar/gkx1220] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/24/2017] [Indexed: 01/25/2023] Open
Abstract
Transcription factors (TFs) are able to associate to their binding sites on DNA faster than the physical limit posed by diffusion. Such high association rates can be achieved by alternating between three-dimensional diffusion and one-dimensional sliding along the DNA chain, a mechanism-dubbed facilitated diffusion. By studying a collection of TF binding sites of Escherichia coli from the RegulonDB database and of Bacillus subtilis from DBTBS, we reveal a funnel in the binding energy landscape around the target sequences. We show that such a funnel is linked to the presence of gradients of AT in the base composition of the DNA region around the binding sites. An extensive computational study of the stochastic sliding process along the energetic landscapes obtained from the database shows that the funnel can significantly enhance the probability of TFs to find their target sequences when sliding in their proximity. We demonstrate that this enhancement leads to a speed-up of the association process.
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Affiliation(s)
- Massimo Cencini
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via dei Taurini 19, 00185 Rome, Italy
| | - Simone Pigolotti
- Biological Complexity Unit, Okinawa Institute of Science and Technology and Graduate University, Onna, Okinawa 904-0495, Japan.,Max Planck Institute for the Physics of Complex Systems, Nöthnitzerstraße 38, 01187 Dresden, Germany.,Departament de Fisica, Universitat Politecnica de Catalunya Edif. GAIA, Rambla Sant Nebridi 22, 08222 Terrassa, Barcelona, Spain
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12
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Paulsen T, Shibata Y, Kumar P, Dillon L, Dutta A. Small extrachromosomal circular DNAs, microDNA, produce short regulatory RNAs that suppress gene expression independent of canonical promoters. Nucleic Acids Res 2019; 47:4586-4596. [PMID: 30828735 PMCID: PMC6511871 DOI: 10.1093/nar/gkz155] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/20/2019] [Accepted: 02/25/2019] [Indexed: 01/17/2023] Open
Abstract
Interest in extrachromosomal circular DNA (eccDNA) molecules has increased recently because of their widespread presence in normal cells across every species ranging from yeast to humans, their increased levels in cancer cells and their overlap with oncogenic and drug-resistant genes. However, the majority of eccDNA (microDNA) in mammalian tissues and cell lines are too small to carry protein coding genes. We have tested functional capabilities of microDNA by creating artificial microDNA molecules mimicking known microDNA sequences and have discovered that they express functional small regulatory RNA including microRNA and novel si-like RNA. MicroDNA are transcribed in vitro and in vivo independent of a canonical promoter sequence. MicroDNA that carry miRNA genes form transcripts that are processed by the endogenous RNA-interference pathway into mature miRNA molecules, which repress a luciferase reporter gene as well as endogenous mRNA targets of the miRNA. Further, microDNA that contain sequences of exons repress the endogenous gene from which the microDNA were derived through the formation of novel si-like RNA. We also show that endogenous microDNA associate with RNA polymerases subunits, POLR2H and POLR3F. Together, these results suggest that microDNA may modulate gene expression through the production of both known and novel regulatory small RNA.
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Affiliation(s)
- Teressa Paulsen
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yoshiyuki Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Pankaj Kumar
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Laura Dillon
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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13
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Silva-Santos AR, Alves CP, Monteiro G, Azevedo AM, Prazeres DMF. Multimodal chromatography of supercoiled minicircles: A closer look into DNA-ligand interactions. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2018.11.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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14
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Lerner LK, Sale JE. Replication of G Quadruplex DNA. Genes (Basel) 2019; 10:genes10020095. [PMID: 30700033 PMCID: PMC6409989 DOI: 10.3390/genes10020095] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 01/03/2023] Open
Abstract
A cursory look at any textbook image of DNA replication might suggest that the complex machine that is the replisome runs smoothly along the chromosomal DNA. However, many DNA sequences can adopt non-B form secondary structures and these have the potential to impede progression of the replisome. A picture is emerging in which the maintenance of processive DNA replication requires the action of a significant number of additional proteins beyond the core replisome to resolve secondary structures in the DNA template. By ensuring that DNA synthesis remains closely coupled to DNA unwinding by the replicative helicase, these factors prevent impediments to the replisome from causing genetic and epigenetic instability. This review considers the circumstances in which DNA forms secondary structures, the potential responses of the eukaryotic replisome to these impediments in the light of recent advances in our understanding of its structure and operation and the mechanisms cells deploy to remove secondary structure from the DNA. To illustrate the principles involved, we focus on one of the best understood DNA secondary structures, G quadruplexes (G4s), and on the helicases that promote their resolution.
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Affiliation(s)
- Leticia Koch Lerner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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15
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Brouns T, De Keersmaecker H, Konrad SF, Kodera N, Ando T, Lipfert J, De Feyter S, Vanderlinden W. Free Energy Landscape and Dynamics of Supercoiled DNA by High-Speed Atomic Force Microscopy. ACS NANO 2018; 12:11907-11916. [PMID: 30346700 DOI: 10.1021/acsnano.8b06994] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
DNA supercoiling fundamentally constrains and regulates the storage and use of genetic information. While the equilibrium properties of supercoiled DNA are relatively well understood, the dynamics of supercoils are much harder to probe. Here we use atomic force microscopy (AFM) imaging to demonstrate that positively supercoiled DNA plasmids, in contrast to their negatively supercoiled counterparts, preserve their plectonemic geometry upon adsorption under conditions that allow for dynamics and equilibration on the surface. Our results are in quantitative agreement with a physical polymer model for supercoiled plasmids that takes into account the known mechanical properties and torque-induced melting of DNA. We directly probe supercoil dynamics using high-speed AFM imaging with subsecond time and ∼nanometer spatial resolution. From our recordings we quantify self-diffusion, branch point flexibility, and slithering dynamics and demonstrate that reconfiguration of molecular extensions is predominantly governed by the bending flexibility of plectoneme arms. We expect that our methodology can be an asset to probe protein-DNA interactions and topochemical reactions on physiological relevant DNA length and supercoiling scales by high-resolution AFM imaging.
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Affiliation(s)
- Tine Brouns
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Herlinde De Keersmaecker
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Sebastian F Konrad
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
| | - Noriyuki Kodera
- Nano-Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi , Kanazawa , 920-1192 , Japan
| | - Toshio Ando
- Nano-Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi , Kanazawa , 920-1192 , Japan
| | - Jan Lipfert
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
| | - Steven De Feyter
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Willem Vanderlinden
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
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16
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Coronel L, Suma A, Micheletti C. Dynamics of supercoiled DNA with complex knots: large-scale rearrangements and persistent multi-strand interlocking. Nucleic Acids Res 2018; 46:7533-7541. [PMID: 29931074 PMCID: PMC6125635 DOI: 10.1093/nar/gky523] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/22/2018] [Accepted: 05/24/2018] [Indexed: 02/04/2023] Open
Abstract
Knots and supercoiling are both introduced in bacterial plasmids by catalytic processes involving DNA strand passages. While the effects on plasmid organization has been extensively studied for knotting and supercoiling taken separately, much less is known about their concurrent action. Here, we use molecular dynamics simulations and oxDNA, an accurate mesoscopic DNA model, to study the kinetic and metric changes introduced by complex (five-crossing) knots and supercoiling in 2 kbp-long DNA rings. We find several unexpected results. First, the conformational ensemble is dominated by two distinct states, differing in branchedness and knot size. Secondly, fluctuations between these states are as fast as the metric relaxation of unknotted rings. In spite of this, certain boundaries of knotted and plectonemically-wound regions can persist over much longer timescales. These pinned regions involve multiple strands that are interlocked by the cooperative action of topological and supercoiling constraints. Their long-lived character may be relevant for the simplifying action of topoisomerases.
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Affiliation(s)
- Lucia Coronel
- SISSA - Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
| | - Antonio Suma
- SISSA - Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA
| | - Cristian Micheletti
- SISSA - Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
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17
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Hunt EA, Evans TC, Tanner NA. Single-stranded binding proteins and helicase enhance the activity of prokaryotic argonautes in vitro. PLoS One 2018; 13:e0203073. [PMID: 30157272 PMCID: PMC6114923 DOI: 10.1371/journal.pone.0203073] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022] Open
Abstract
Prokaryotic argonautes are a unique class of nucleic acid-guided endonucleases putatively involved in cellular defense against foreign genetic elements. While their eukaryotic homologs and Cas protein counterparts require single-stranded RNAs as guides, some prokaryotic argonautes are able to utilize short single-stranded DNAs as guides for sequence-specific endonuclease activity. Many complications currently prevent the use of prokaryotic argonautes for in vivo gene-editing applications; however, they do exhibit potential as a new class of in vitro molecular tools if certain challenges can be overcome, specifically the limitations on substrate accessibility which leads to unequal levels of activity across a broad palate of substrates and the inability to act on double-stranded DNA substrates. Here we demonstrate the use of accessory factors, including thermostable single-stranded DNA binding proteins and UvrD-like helicase, in conjunction with prokaryotic argonautes to significantly improve enzymatic activity and enable functionality with a broader range of substrates, including linear double-stranded DNA substrates. We also demonstrate the use of Thermus thermophilus argonaute with accessory factors as a programmable restriction enzyme to generate long, unique single-stranded overhangs from linear double-stranded substrates compatible with downstream ligation.
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Affiliation(s)
- Eric A. Hunt
- New England Biolabs, Inc., Ipswich, Massachusetts, United States of America
| | - Thomas C. Evans
- New England Biolabs, Inc., Ipswich, Massachusetts, United States of America
| | - Nathan A. Tanner
- New England Biolabs, Inc., Ipswich, Massachusetts, United States of America
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18
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Probing hyper-negatively supercoiled mini-circles with nucleases and DNA binding proteins. PLoS One 2018; 13:e0202138. [PMID: 30114256 PMCID: PMC6095550 DOI: 10.1371/journal.pone.0202138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/28/2018] [Indexed: 02/08/2023] Open
Abstract
It is well accepted that the introduction of negative supercoils locally unwinds the DNA double helix, influencing thus the activity of proteins. Despite the use of recent methods of molecular dynamics simulations to model the DNA supercoiling-induced DNA deformation, the precise extent and location of unpaired bases induced by the negative supercoiling have never been investigated at the nucleotide level. Our goals in this study were to use radiolabeled double-stranded DNA mini-circles (dsMCs) to locate the unpaired bases on dsMCs whose topology ranged from relaxed to hyper-negatively supercoiled states, and to characterize the binding of proteins involved in the DNA metabolism. Our results show that the Nuclease SI is nearly ten times more active on hyper-negatively supercoiled than relaxed DNA. The structural changes responsible for this stimulation of activity were mapped for the first time with a base pair resolution and shown to be subtle and distributed along the entire sequence. As divalent cations modify the DNA topology, our binding studies were conducted with or without magnesium. Without magnesium, the dsMCs topoisomers mostly differ by their twist. Under these conditions, the Escherichia coli topoisomerase I weakly binds relaxed dsMCs and exhibits a stronger binding on negatively and hyper-negatively supercoiled dsMCs than relaxed dsMCs, with no significant difference in the binding activity among the supercoiled topoisomers. For the human replication protein A (hRPA), the more negatively supercoiled is the DNA, the better the binding, illustrating the twist-dependent binding activity for this protein. The presence of magnesium permits the dsMCs to writhe upon introduction of negative supercoiling and greatly modifies the binding properties of the hRPA and Escherichia coli SSB on dsMCs, indicating a magnesium-dependent DNA binding behavior. Finally, our experiments that probe the topology of the DNA in the hRPA-dsMC complexes show that naked and hRPA-bound dsMCs have the same topology.
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19
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Zoli M. End-to-end distance and contour length distribution functions of DNA helices. J Chem Phys 2018; 148:214902. [DOI: 10.1063/1.5021639] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Marco Zoli
- School of Science and Technology, University of Camerino, I-62032 Camerino, Italy
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20
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Sheppard EC, Morrish RB, Dillon MJ, Leyland R, Chahwan R. Epigenomic Modifications Mediating Antibody Maturation. Front Immunol 2018. [PMID: 29535729 PMCID: PMC5834911 DOI: 10.3389/fimmu.2018.00355] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Epigenetic modifications, such as histone modifications, DNA methylation status, and non-coding RNAs (ncRNA), all contribute to antibody maturation during somatic hypermutation (SHM) and class-switch recombination (CSR). Histone modifications alter the chromatin landscape and, together with DNA primary and tertiary structures, they help recruit Activation-Induced Cytidine Deaminase (AID) to the immunoglobulin (Ig) locus. AID is a potent DNA mutator, which catalyzes cytosine-to-uracil deamination on single-stranded DNA to create U:G mismatches. It has been shown that alternate chromatin modifications, in concert with ncRNAs and potentially DNA methylation, regulate AID recruitment and stabilize DNA repair factors. We, hereby, assess the combination of these distinct modifications and discuss how they contribute to initiating differential DNA repair pathways at the Ig locus, which ultimately leads to enhanced antibody–antigen binding affinity (SHM) or antibody isotype switching (CSR). We will also highlight how misregulation of epigenomic regulation during DNA repair can compromise antibody development and lead to a number of immunological syndromes and cancer.
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Affiliation(s)
- Emily C Sheppard
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | | | - Michael J Dillon
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | | | - Richard Chahwan
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
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21
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Liebl K, Zacharias M. Unwinding Induced Melting of Double-Stranded DNA Studied by Free Energy Simulations. J Phys Chem B 2017; 121:11019-11030. [PMID: 29064703 DOI: 10.1021/acs.jpcb.7b07701] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
DNA unwinding plays a major role in many biological processes, such as replication, transcription, and repair. It can lead to local melting and strand separation and can serve as a key mechanism to promote access to the separate strands of a double-stranded DNA. While DNA unwinding has been investigated extensively by DNA cyclization and single-molecule studies on a length-scale of kilo base pairs, it is neither fully understood at the base pair level nor at the level of molecular interactions. By employing a torque acting on the termini of DNA oligonucleotides during molecular dynamics free energy simulations, we locally unwind the central part of a DNA beyond an elastic (harmonic) regime. The simulations reproduce experimental results on the twist elasticity in the harmonic regime (characterized by a mostly quadratic free energy change with respect to changes in twist) and a deformation up to 7° was found as a limit of the harmonic response. Beyond this limit the free energy increase per twist change dropped dramatically coupled to local base pair disruptions and significant deformation of the nucleic acid backbone structure. Restriction of the DNA bending flexibility resulted in a stiffer harmonic response and an earlier onset of the anharmonic response. Whereas local melting with a complete disruption of base pairing and flipping of nucleotides was observed in case of an AT rich central segment strong backbone changes and changes in the stacking arrangements were observed in case of a GC rich segment. Unrestrained MD simulations starting from locally melted DNA reformed regular B-DNA after 50-300 ns simulation time. The simulations may have important implications for understanding DNA recognition processes coupled with significant structural alterations.
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Affiliation(s)
- Korbinian Liebl
- Physik-Department T38, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany
| | - Martin Zacharias
- Physik-Department T38, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany
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22
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Fosado YAG, Michieletto D, Marenduzzo D. Dynamical Scaling and Phase Coexistence in Topologically Constrained DNA Melting. PHYSICAL REVIEW LETTERS 2017; 119:118002. [PMID: 28949232 DOI: 10.1103/physrevlett.119.118002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Indexed: 06/07/2023]
Abstract
There is a long-standing experimental observation that the melting of topologically constrained DNA, such as circular closed plasmids, is less abrupt than that of linear molecules. This finding points to an important role of topology in the physics of DNA denaturation, which is, however, poorly understood. Here, we shed light on this issue by combining large-scale Brownian dynamics simulations with an analytically solvable phenomenological Landau mean field theory. We find that the competition between melting and supercoiling leads to phase coexistence of denatured and intact phases at the single-molecule level. This coexistence occurs in a wide temperature range, thereby accounting for the broadening of the transition. Finally, our simulations show an intriguing topology-dependent scaling law governing the growth of denaturation bubbles in supercoiled plasmids, which can be understood within the proposed mean field theory.
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Affiliation(s)
- Y A G Fosado
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - D Michieletto
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - D Marenduzzo
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
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23
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Wang Q, Irobalieva RN, Chiu W, Schmid MF, Fogg JM, Zechiedrich L, Pettitt BM. Influence of DNA sequence on the structure of minicircles under torsional stress. Nucleic Acids Res 2017; 45:7633-7642. [PMID: 28609782 PMCID: PMC5737869 DOI: 10.1093/nar/gkx516] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/26/2017] [Accepted: 06/01/2017] [Indexed: 01/09/2023] Open
Abstract
The sequence dependence of the conformational distribution of DNA under various levels of torsional stress is an important unsolved problem. Combining theory and coarse-grained simulations shows that the DNA sequence and a structural correlation due to topology constraints of a circle are the main factors that dictate the 3D structure of a 336 bp DNA minicircle under torsional stress. We found that DNA minicircle topoisomers can have multiple bend locations under high torsional stress and that the positions of these sharp bends are determined by the sequence, and by a positive mechanical correlation along the sequence. We showed that simulations and theory are able to provide sequence-specific information about individual DNA minicircles observed by cryo-electron tomography (cryo-ET). We provided a sequence-specific cryo-ET tomogram fitting of DNA minicircles, registering the sequence within the geometric features. Our results indicate that the conformational distribution of minicircles under torsional stress can be designed, which has important implications for using minicircle DNA for gene therapy.
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Affiliation(s)
- Qian Wang
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Rossitza N. Irobalieva
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Wah Chiu
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F. Schmid
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jonathan M. Fogg
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston TX, 77030, USA
| | - Lynn Zechiedrich
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston TX, 77030, USA
| | - B. Montgomery Pettitt
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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24
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Krajina BA, Spakowitz AJ. Large-Scale Conformational Transitions in Supercoiled DNA Revealed by Coarse-Grained Simulation. Biophys J 2017; 111:1339-1349. [PMID: 27705758 DOI: 10.1016/j.bpj.2016.07.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/26/2016] [Accepted: 07/28/2016] [Indexed: 02/07/2023] Open
Abstract
Topological constraints, such as those associated with DNA supercoiling, play an integral role in genomic regulation and organization in living systems. However, physical understanding of the principles that underlie DNA organization at biologically relevant length scales remains a formidable challenge. We develop a coarse-grained simulation approach for predicting equilibrium conformations of supercoiled DNA. Our methodology enables the study of supercoiled DNA molecules at greater length scales and supercoiling densities than previously explored by simulation. With this approach, we study the conformational transitions that arise due to supercoiling across the full range of supercoiling densities that are commonly explored by living systems. Simulations of ring DNA molecules with lengths at the scale of topological domains in the Escherichia coli chromosome (∼10 kilobases) reveal large-scale conformational transitions elicited by supercoiling. The conformational transitions result in three supercoiling conformational regimes that are governed by a competition among chiral coils, extended plectonemes, and branched hyper-supercoils. These results capture the nonmonotonic relationship of size versus degree of supercoiling observed in experimental sedimentation studies of supercoiled DNA, and our results provide a physical explanation of the conformational transitions underlying this behavior. The length scales and supercoiling regimes investigated here coincide with those relevant to transcription-coupled remodeling of supercoiled topological domains, and we discuss possible implications of these findings in terms of the interplay between transcription and topology in bacterial chromosome organization.
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Affiliation(s)
- Brad A Krajina
- Department of Chemical Engineering, Stanford University, Stanford, California
| | - Andrew J Spakowitz
- Department of Chemical Engineering, Stanford University, Stanford, California; Department of Applied Physics, Stanford University, Stanford, California; Department of Materials Science and Engineering, Stanford University, Stanford, California; Biophysics Program, Stanford University, Stanford, California.
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25
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Japaridze A, Muskhelishvili G, Benedetti F, Gavriilidou AFM, Zenobi R, De Los Rios P, Longo G, Dietler G. Hyperplectonemes: A Higher Order Compact and Dynamic DNA Self-Organization. NANO LETTERS 2017; 17:1938-1948. [PMID: 28191853 DOI: 10.1021/acs.nanolett.6b05294] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Bacterial chromosome has a compact structure that dynamically changes its shape in response to bacterial growth rate and growth phase. Determining how chromatin remains accessible to DNA binding proteins, and transcription machinery is crucial to understand the link between genetic regulation, DNA structure, and topology. Here, we study very large supercoiled dsDNA using high-resolution characterization, theoretical modeling, and molecular dynamics calculations. We unveil a new type of highly ordered DNA organization forming in the presence of attractive DNA-DNA interactions, which we call hyperplectonemes. We demonstrate that their formation depends on DNA size, supercoiling, and bacterial physiology. We compare structural, nanomechanic, and dynamic properties of hyperplectonemes bound by three highly abundant nucleoid-associated proteins (FIS, H-NS, and HU). In all these cases, the negative supercoiling of DNA determines molecular dynamics, modulating their 3D shape. Overall, our findings provide a mechanistic insight into the critical role of DNA topology in genetic regulation.
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Affiliation(s)
- Aleksandre Japaridze
- Laboratory of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Georgi Muskhelishvili
- Jacobs University , D-28759 Bremen, Germany
- Agricultural University of Georgia , 0159 Tbilisi, Georgia
| | - Fabrizio Benedetti
- Center for Integrative Genomics, University of Lausanne , 1015 Lausanne, Switzerland
- Vital-IT, SIB Swiss Institute of Bioinformatics , 1015 Lausanne, Switzerland
| | - Agni F M Gavriilidou
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich , 8093 Zurich, Switzerland
| | - Renato Zenobi
- Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich , 8093 Zurich, Switzerland
| | - Paolo De Los Rios
- Vital-IT, SIB Swiss Institute of Bioinformatics , 1015 Lausanne, Switzerland
- Laboratoire de Biophysique Statistique, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Giovanni Longo
- Laboratory of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche , Rome, Italy
| | - Giovanni Dietler
- Laboratory of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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26
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Takahashi S, Motooka S, Kawasaki S, Kurita H, Mizuno T, Matsuura SI, Hanaoka F, Mizuno A, Oshige M, Katsura S. Direct single-molecule observations of DNA unwinding by SV40 large tumor antigen under a negative DNA supercoil state. J Biomol Struct Dyn 2017; 36:32-44. [PMID: 27928933 DOI: 10.1080/07391102.2016.1269689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Superhelices, which are induced by the twisting and coiling of double-helical DNA in chromosomes, are thought to affect transcription, replication, and other DNA metabolic processes. In this study, we report the effects of negative supercoiling on the unwinding activity of simian virus 40 large tumor antigen (SV40 TAg) at a single-molecular level. The supercoiling density of linear DNA templates was controlled using magnetic tweezers and monitored using a fluorescent microscope in a flow cell. SV40 TAg-mediated DNA unwinding under relaxed and negative supercoil states was analyzed by the direct observation of both single- and double-stranded regions of single DNA molecules. Increased negative superhelicity stimulated SV40 TAg-mediated DNA unwinding more strongly than a relaxed state; furthermore, negative superhelicity was associated with an increased probability of SV40 TAg-mediated DNA unwinding. These results suggest that negative superhelicity helps to regulate the initiation of DNA replication.
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Affiliation(s)
- Shunsuke Takahashi
- a Department of Environmental Engineering Science, Graduate School of Science and Technology , Gunma University , Kiryu , Japan.,f Japan Society for the Promotion of Science
| | - Shinya Motooka
- a Department of Environmental Engineering Science, Graduate School of Science and Technology , Gunma University , Kiryu , Japan
| | - Shohei Kawasaki
- a Department of Environmental Engineering Science, Graduate School of Science and Technology , Gunma University , Kiryu , Japan
| | - Hirofumi Kurita
- b Department of Environmental and Life Sciences, Graduate School of Engineering , Toyohashi University of Technology , Toyohashi , Japan
| | - Takeshi Mizuno
- c Cellular Dynamics Laboratory , RIKEN, Wako , Saitama , Japan
| | - Shun-Ichi Matsuura
- d Research Institute for Chemical Process Technology , National Institute of Advanced Industrial Science and Technology (AIST) , Sendai , Japan
| | - Fumio Hanaoka
- e Faculty of Science, Institute for Biomolecular Science , Gakushuin University , Tokyo , Japan
| | - Akira Mizuno
- b Department of Environmental and Life Sciences, Graduate School of Engineering , Toyohashi University of Technology , Toyohashi , Japan
| | - Masahiko Oshige
- a Department of Environmental Engineering Science, Graduate School of Science and Technology , Gunma University , Kiryu , Japan
| | - Shinji Katsura
- a Department of Environmental Engineering Science, Graduate School of Science and Technology , Gunma University , Kiryu , Japan
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27
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Singh A, Singh N. DNA melting in the presence of molecular crowders. Phys Chem Chem Phys 2017; 19:19452-19460. [DOI: 10.1039/c7cp03624h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the opening of double stranded DNA (dsDNA) in the presence of molecular crowders using the Peyrard–Bishop–Dauxois (PBD) model.
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Affiliation(s)
- Amar Singh
- Department of Physics
- BITS Pilani
- Pilani Campus
- India
| | - Navin Singh
- Department of Physics
- BITS Pilani
- Pilani Campus
- India
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28
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Fosado YAG, Michieletto D, Allan J, Brackley CA, Henrich O, Marenduzzo D. A single nucleotide resolution model for large-scale simulations of double stranded DNA. SOFT MATTER 2016; 12:9458-9470. [PMID: 27845464 DOI: 10.1039/c6sm01859a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The computational modelling of DNA is becoming crucial in light of new advances in DNA nano-technology, single-molecule experiments and in vivo DNA tampering. Here we present a mesoscopic model for double stranded DNA (dsDNA) at the single nucleotide level which retains the characteristic helical structure, while being able to simulate large molecules - up to a million base pairs - for time-scales which are relevant to physiological processes. This is made possible by an efficient and highly-parallelised implementation of the model which we discuss here. The model captures the main characteristics of DNA, such as the different persistence lengths for double and single strands, pitch, torsional rigidity and the presence of major and minor grooves. The model constitutes a starting point for the future implementation of further features, such as sequence specificity and electrostatic repulsion. We show that the behaviour of the presented model compares favourably with single molecule experiments where dsDNA is manipulated by external forces or torques. We finally present some results on the kinetics of denaturation of linear DNA and supercoiling of closed dsDNA molecules.
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Affiliation(s)
- Y A G Fosado
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK
| | - D Michieletto
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK
| | - J Allan
- Institute of Genetics and Molecular Medicine, MRC Human Genetics Unit, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - C A Brackley
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK
| | - O Henrich
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK and EPCC, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK
| | - D Marenduzzo
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, Scotland, UK
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29
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Ghosh SK, Cherstvy AG, Petrov EP, Metzler R. Interactions of rod-like particles on responsive elastic sheets. SOFT MATTER 2016; 12:7908-19. [PMID: 27492050 DOI: 10.1039/c6sm01522k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
What are the physical laws of the mutual interactions of objects bound to cell membranes, such as various membrane proteins or elongated virus particles? To rationalise this, we here investigate by extensive computer simulations mutual interactions of rod-like particles adsorbed on the surface of responsive elastic two-dimensional sheets. Specifically, we quantify sheet deformations as a response to adhesion of such filamentous particles. We demonstrate that tip-to-tip contacts of rods are favoured for relatively soft sheets, while side-by-side contacts are preferred for stiffer elastic substrates. These attractive orientation-dependent substrate-mediated interactions between the rod-like particles on responsive sheets can drive their aggregation and self-assembly. The optimal orientation of the membrane-bound rods is established via responding to the elastic energy profiles created around the particles. We unveil the phase diagramme of attractive-repulsive rod-rod interactions in the plane of their separation and mutual orientation. Applications of our results to other systems featuring membrane-associated particles are also discussed.
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Affiliation(s)
- Surya K Ghosh
- TIMC-IMAG Laboratory, Universite Grenoble Alpes, CNRS UMR, 5525 Grenoble, France
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30
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Abstract
We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 - d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5.
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31
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Romanello M, Schiavone D, Frey A, Sale JE. Histone H3.3 promotes IgV gene diversification by enhancing formation of AID-accessible single-stranded DNA. EMBO J 2016; 35:1452-64. [PMID: 27220848 PMCID: PMC4883027 DOI: 10.15252/embj.201693958] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/25/2016] [Indexed: 11/30/2022] Open
Abstract
Immunoglobulin diversification is driven by activation‐induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single‐stranded DNA (ssDNA), the enzymatic substrate of AID. Here, we report that chicken DT40 cells lacking variant histone H3.3 exhibit reduced IgV sequence diversification. We show that this results from impairment of the ability of AID to access the IgV genes due to reduced formation of ssDNA during IgV transcription. Loss of H3.3 also diminishes IgV R‐loop formation. However, reducing IgV R‐loops by RNase HI overexpression in wild‐type cells does not affect IgV diversification, showing that these structures are not necessary intermediates for AID access. Importantly, the reduction in the formation of AID‐accessible ssDNA in cells lacking H3.3 is independent of any effect on the level of transcription or the kinetics of RNAPII elongation, suggesting the presence of H3.3 in the nucleosomes of the IgV genes increases the chances of the IgV DNA becoming single‐stranded, thereby creating an effective AID substrate.
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Affiliation(s)
- Marina Romanello
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Davide Schiavone
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Alexander Frey
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Julian E Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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32
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Shi C, Shang F, Zhou M, Zhang P, Wang Y, Ma C. Triggered isothermal PCR by denaturation bubble-mediated strand exchange amplification. Chem Commun (Camb) 2016; 52:11551-4. [DOI: 10.1039/c6cc05906f] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Here, we introduced the concept of strand exchange amplification (SEA) mediated by denaturation bubbles.
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Affiliation(s)
- Chao Shi
- College of Life Sciences
- Qingdao University
- Qingdao
- P. R. China
| | - Fanjin Shang
- Key Laboratory of Sensor Analysis of Tumor Marker
- Ministry of Education
- College of Chemistry and Molecular Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Meiling Zhou
- Key Laboratory of Sensor Analysis of Tumor Marker
- Ministry of Education
- College of Chemistry and Molecular Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Pansong Zhang
- College of Chemical Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
- P. R. China
| | - Yifan Wang
- Key Laboratory of Sensor Analysis of Tumor Marker
- Ministry of Education
- College of Chemistry and Molecular Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Cuiping Ma
- Key Laboratory of Sensor Analysis of Tumor Marker
- Ministry of Education
- College of Chemistry and Molecular Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
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33
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Sicard F, Destainville N, Manghi M. DNA denaturation bubbles: free-energy landscape and nucleation/closure rates. J Chem Phys 2015; 142:034903. [PMID: 25612729 DOI: 10.1063/1.4905668] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The issue of the nucleation and slow closure mechanisms of non-superhelical stress-induced denaturation bubbles in DNA is tackled using coarse-grained MetaDynamics and Brownian simulations. A minimal mesoscopic model is used where the double helix is made of two interacting bead-spring rotating strands with a prescribed torsional modulus in the duplex state. We demonstrate that timescales for the nucleation (respectively, closure) of an approximately 10 base-pair bubble, in agreement with experiments, are associated with the crossing of a free-energy barrier of 22 kBT (respectively, 13 kBT) at room temperature T. MetaDynamics allows us to reconstruct accurately the free-energy landscape, to show that the free-energy barriers come from the difference in torsional energy between the bubble and duplex states, and thus to highlight the limiting step, a collective twisting, that controls the nucleation/closure mechanism, and to access opening time scales on the millisecond range. Contrary to small breathing bubbles, those more than 4 base-pair bubbles are of biological relevance, for example, when a pre-existing state of denaturation is required by specific DNA-binding proteins.
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Affiliation(s)
- François Sicard
- Université de Toulouse, UPS, Laboratoire de Physique Théorique (IRSAMC), F-31062 Toulouse, France
| | - Nicolas Destainville
- Université de Toulouse, UPS, Laboratoire de Physique Théorique (IRSAMC), F-31062 Toulouse, France
| | - Manoel Manghi
- Université de Toulouse, UPS, Laboratoire de Physique Théorique (IRSAMC), F-31062 Toulouse, France
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34
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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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35
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Wang Q, Myers CG, Pettitt BM. Twist-induced defects of the P-SSP7 genome revealed by modeling the cryo-EM density. J Phys Chem B 2015; 119:4937-43. [PMID: 25793549 DOI: 10.1021/acs.jpcb.5b00865] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We consider the consequences of assuming that DNA inside of phages can be approximated as a strongly nonlinear persistence length polymer. Recent cryo-EM experiments find a hole in the density map of P-SSP7 phage, located in the DNA segment filling the portal channel of the phage. We use experimentally derived structural constraints with coarse-grained simulation techniques to consider contrasting model interpretations of reconstructed density in the portal channel. The coarse-grained DNA models used are designed to capture the effects of torsional strain and electrostatic environment. Our simulation results are consistent with the interpretation that the vacancy or hole in the experimental density map is due to DNA strain leading to strand separation. We further demonstrate that a moderate negative twisting strain is able to account for the strand separation. This effect of nonlinear persistence length may be important in other aspects of phage DNA packing.
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Affiliation(s)
- Qian Wang
- †Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-0304, United States
| | - Christopher G Myers
- ‡Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, Texas 77030, United States
| | - B Montgomery Pettitt
- †Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-0304, United States.,‡Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, Texas 77030, United States
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36
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Pal T, Sadhukhan P, Bhattacharjee SM. Efimov-like phase of a three-stranded DNA and the renormalization-group limit cycle. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:042105. [PMID: 25974437 DOI: 10.1103/physreve.91.042105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Indexed: 06/04/2023]
Abstract
A three-stranded DNA with short range base pairings only is known to exhibit a classical analog of the quantum Efimov effect, viz., a three-chain bound state at the two-chain melting point where no two are bound. By using a nonperturbative renormalization-group method for a rigid duplex DNA and a flexible third strand, with base pairings and strand exchange, we show that the Efimov-DNA is associated with a limit cycle type behavior of the flow of an effective three-chain interaction. The analysis also shows that thermally generated bubbles play an essential role in producing the effect. A toy model for the flow equations shows the limit cycle in an extended three-dimensional parameter space of the two-chain coupling and a complex three-chain interaction.
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Affiliation(s)
- Tanmoy Pal
- Institute of Physics, Bhubaneswar 751005, India
| | | | - Somendra M Bhattacharjee
- Institute of Physics, Bhubaneswar 751005, India
- Department of Physics, Ramakrishna Mission Vivekananda University, Belur Math, West Bengal 711202, India
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37
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Takahashi S, Motooka S, Usui T, Kawasaki S, Miyata H, Kurita H, Mizuno T, Matsuura SI, Mizuno A, Oshige M, Katsura S. Direct single-molecule observations of local denaturation of a DNA double helix under a negative supercoil state. Anal Chem 2015; 87:3490-7. [PMID: 25697222 DOI: 10.1021/acs.analchem.5b00044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Effects of a negative supercoil on the local denaturation of the DNA double helix were studied at the single-molecule level. The local denaturation in λDNA and λDNA containing the SV40 origin of DNA replication (SV40ori-λDNA) was directly observed by staining single-stranded DNA regions with a fusion protein comprising the ssDNA binding domain of a 70-kDa subunit of replication protein A and an enhanced yellow fluorescent protein (RPA-YFP) followed by staining the double-stranded DNA regions with YOYO-1. The local denaturation of λDNA and SV40ori-λDNA under a negative supercoil state was observed as single bright spots at the single-stranded regions. When negative supercoil densities were gradually increased to 0, -0.045, and -0.095 for λDNA and 0, -0.047, and -0.1 for SV40ori-λDNA, single bright spots at the single-stranded regions were frequently induced under higher negative supercoil densities of -0.095 for λDNA and -0.1 for SV40ori-λDNA. However, single bright spots of the single-stranded regions were rarely observed below a negative supercoil density of -0.045 and -0.047 for λDNA and SV40ori-λDNA, respectively. The probability of occurrence of the local denaturation increased with negative superhelicity for both λDNA and SV40ori-λDNA.
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Affiliation(s)
- Shunsuke Takahashi
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Shinya Motooka
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Tomohiro Usui
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Shohei Kawasaki
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Hidefumi Miyata
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Hirofumi Kurita
- ‡Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology, Aichi 441-8580, Japan
| | - Takeshi Mizuno
- §Cellular Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Shun-ichi Matsuura
- ∥Research Center for Compact Chemical System, National Institute of Advanced Industrial Science and Technology (AIST), Miyagi 983-8551, Japan
| | - Akira Mizuno
- ‡Department of Environmental and Life Sciences, Graduate School of Engineering, Toyohashi University of Technology, Aichi 441-8580, Japan
| | - Masahiko Oshige
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
| | - Shinji Katsura
- †Department of Environmental Engineering Science, Graduate School of Science and Technology, Gunma University, Gunma 376-8515, Japan
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38
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39
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Coexistence of twisted, plectonemic, and melted DNA in small topological domains. Biophys J 2014; 106:1174-81. [PMID: 24606941 DOI: 10.1016/j.bpj.2014.01.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/13/2014] [Accepted: 01/13/2014] [Indexed: 01/19/2023] Open
Abstract
DNA responds to small changes in force and torque by over- or undertwisting, forming plectonemes, and/or melting bubbles. Although transitions between either twisted and plectonemic conformations or twisted and melted conformations have been described as first-order phase transitions, we report here a broadening of these transitions when the size of a topological domain spans several kilobasepairs. Magnetic tweezers measurements indicate the coexistence of three conformations at subpicoNewton force and linking number densities ∼-0.06. We present a statistical physics model for DNA domains of several kilobasepairs by calculating the full partition function that describes this three-state coexistence. Real-time analysis of short DNA tethers at constant force and torque shows discrete levels of extension, representing discontinuous changes in the size of the melting bubble, which should reflect the underlying DNA sequence. Our results provide a comprehensive picture of the structure of underwound DNA at low force and torque and could have important consequences for various biological processes, in particular those that depend on local DNA melting, such as the initiation of replication and transcription.
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40
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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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41
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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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42
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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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43
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Jeon JH, Sung W. An effective mesoscopic model of double-stranded DNA. J Biol Phys 2014; 40:1-14. [PMID: 24306264 PMCID: PMC3923960 DOI: 10.1007/s10867-013-9333-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 10/11/2013] [Indexed: 11/26/2022] Open
Abstract
Watson and Crick's epochal presentation of the double helix structure in 1953 has paved the way to intense exploration of DNA's vital functions in cells. Also, recent advances of single molecule techniques have made it possible to probe structures and mechanics of constrained DNA at length scales ranging from nanometers to microns. There have been a number of atomistic scale quantum chemical calculations or molecular level simulations, but they are too computationally demanding or analytically unfeasible to describe the DNA conformation and mechanics at mesoscopic levels. At micron scales, on the other hand, the wormlike chain model has been very instrumental in describing analytically the DNA mechanics but lacks certain molecular details that are essential in describing the hybridization, nano-scale confinement, and local denaturation. To fill this fundamental gap, we present a workable and predictive mesoscopic model of double-stranded DNA where the nucleotides beads constitute the basic degrees of freedom. With the inter-strand stacking given by an interaction between diagonally opposed monomers, the model explains with analytical simplicity the helix formation and produces a generalized wormlike chain model with the concomitant large bending modulus given in terms of the helical structure and stiffness. It also explains how the helical conformation undergoes overstretch transition to the ladder-like conformation at a force plateau, in agreement with the experiment.
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Affiliation(s)
- Jae-Hyung Jeon
- />Department of Physics and PCTP, Pohang University of Science and Technology, Pohang, 790-784 Republic of Korea
| | - Wokyung Sung
- />Department of Physics and PCTP, Pohang University of Science and Technology, Pohang, 790-784 Republic of Korea
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44
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Bohr J, Olsen KW. Total positive curvature of circular DNA. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:052714. [PMID: 24329303 DOI: 10.1103/physreve.88.052714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 08/15/2013] [Indexed: 06/03/2023]
Abstract
The properties of double-stranded DNA and other chiral molecules depend on the local geometry, i.e., on curvature and torsion, yet the paths of closed chain molecules are globally restricted by topology. When both of these characteristics are to be incorporated in the description of circular chain molecules, e.g., plasmids, it is shown to have implications for the total positive curvature integral. For small circular micro-DNAs it follows as a consequence of Fenchel's inequality that there must exist a minimum length for the circular plasmids to be double stranded. It also follows that all circular micro-DNAs longer than the minimum length must be concave, a result that is consistent with typical atomic force microscopy images of plasmids. Predictions for the total positive curvature of circular micro-DNAs are given as a function of length, and comparisons with circular DNAs from the literature are presented.
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Affiliation(s)
- Jakob Bohr
- DTU Nanotech, Building 345Ø, Ørsteds Plads, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Kasper W Olsen
- DTU Nanotech, Building 345Ø, Ørsteds Plads, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
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45
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Cerreta A, Vobornik D, Dietler G. Fine DNA structure revealed by constant height frequency modulation AFM imaging. Eur Polym J 2013. [DOI: 10.1016/j.eurpolymj.2013.03.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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46
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47
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Manghi M, Destainville N, Palmeri J. Mesoscopic models for DNA stretching under force: New results and comparison with experiments. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:110. [PMID: 23099534 DOI: 10.1140/epje/i2012-12110-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 09/21/2012] [Accepted: 09/26/2012] [Indexed: 06/01/2023]
Abstract
Single-molecule experiments on double-stranded B-DNA stretching have revealed one or two structural transitions, when increasing the external force. They are characterized by a sudden increase of DNA contour length and a decrease of the bending rigidity. The nature and the critical forces of these transitions depend on DNA base sequence, loading rate, salt conditions and temperature. It has been proposed that the first transition, at forces of 60-80 pN, is a transition from B to S-DNA, viewed as a stretched duplex DNA, while the second one, at stronger forces, is a strand peeling resulting in single-stranded DNAs (ssDNA), similar to thermal denaturation. But due to experimental conditions these two transitions can overlap, for instance for poly(dA-dT). In an attempt to propose a coherent picture compatible with this variety of experimental observations, we derive an analytical formula using a coupled discrete worm-like chain-Ising model. Our model takes into account bending rigidity, discreteness of the chain, linear and non-linear (for ssDNA) bond stretching. In the limit of zero force, this model simplifies into a coupled model already developed by us for studying thermal DNA melting, establishing a connection with previous fitting parameter values for denaturation profiles. Our results are summarized as follows: i) ssDNA is fitted, using an analytical formula, over a nano-Newton range with only three free parameters, the contour length, the bending modulus and the monomer size; ii) a surprisingly good fit on this force range is possible only by choosing a monomer size of 0.2 nm, almost 4 times smaller than the ssDNA nucleobase length; iii) mesoscopic models are not able to fit B to ssDNA (or S to ss) transitions; iv) an analytical formula for fitting B to S transitions is derived in the strong force approximation and for long DNAs, which is in excellent agreement with exact transfer matrix calculations; v) this formula fits perfectly well poly(dG-dC) and λ-DNA force-extension curves with consistent parameter values; vi) a coherent picture, where S to ssDNA transitions are much more sensitive to base-pair sequence than the B to S one, emerges. This relatively simple model might allow one to further study quantitatively the influence of salt concentration and base-pairing interactions on DNA force-induced transitions.
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Affiliation(s)
- Manoel Manghi
- Laboratoire de Physique Théorique (IRSAMC), Université de Toulouse, UPS, F-31062, Toulouse, France.
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48
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Matek C, Ouldridge TE, Levy A, Doye JPK, Louis AA. DNA cruciform arms nucleate through a correlated but asynchronous cooperative mechanism. J Phys Chem B 2012; 116:11616-25. [PMID: 22931199 DOI: 10.1021/jp3080755] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Inverted repeat (IR) sequences in DNA can form noncanonical cruciform structures to relieve torsional stress. We use Monte Carlo simulations of a recently developed coarse-grained model of DNA to demonstrate that the nucleation of a cruciform can proceed through a cooperative mechanism. First, a twist-induced denaturation bubble must diffuse so that its midpoint is near the center of symmetry of the IR sequence. Second, bubble fluctuations must be large enough to allow one of the arms to form a small number of hairpin bonds. Once the first arm is partially formed, the second arm can rapidly grow to a similar size. Because bubbles can twist back on themselves, they need considerably fewer bases to resolve torsional stress than the final cruciform state does. The initially stabilized cruciform therefore continues to grow, which typically proceeds synchronously, reminiscent of the S-type mechanism of cruciform formation. By using umbrella sampling techniques, we calculate, for different temperatures and superhelical densities, the free energy as a function of the number of bonds in each cruciform arm along the correlated but asynchronous nucleation pathways we observed in direct simulations.
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Affiliation(s)
- Christian Matek
- Rudolph Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK
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49
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Alexandrov BS, Fukuyo Y, Lange M, Horikoshi N, Gelev V, Rasmussen KØ, Bishop AR, Usheva A. DNA breathing dynamics distinguish binding from nonbinding consensus sites for transcription factor YY1 in cells. Nucleic Acids Res 2012; 40:10116-23. [PMID: 22904068 PMCID: PMC3488223 DOI: 10.1093/nar/gks758] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The genome-wide mapping of the major gene expression regulators, the transcription factors (TFs) and their DNA binding sites, is of great importance for describing cellular behavior and phenotypic diversity. Presently, the methods for prediction of genomic TF binding produce a large number of false positives, most likely due to insufficient description of the physiochemical mechanisms of protein–DNA binding. Growing evidence suggests that, in the cell, the double-stranded DNA (dsDNA) is subject to local transient strands separations (breathing) that contribute to genomic functions. By using site-specific chromatin immunopecipitations, gel shifts, BIOBASE data, and our model that accurately describes the melting behavior and breathing dynamics of dsDNA we report a specific DNA breathing profile found at YY1 binding sites in cells. We find that the genomic flanking sequence variations and SNPs, may exert long-range effects on DNA dynamics and predetermine YY1 binding. The ubiquitous TF YY1 has a fundamental role in essential biological processes by activating, initiating or repressing transcription depending upon the sequence context it binds. We anticipate that consensus binding sequences together with the related DNA dynamics profile may significantly improve the accuracy of genomic TF binding sites and TF binding-related functional SNPs.
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Affiliation(s)
- Boian S Alexandrov
- Harvard Medical School, Department of Medicine, Endocrinology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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Zoli M. Anharmonic stacking in supercoiled DNA. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:195103. [PMID: 22495298 DOI: 10.1088/0953-8984/24/19/195103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Multistep denaturation in a short circular DNA molecule is analyzed by a mesoscopic Hamiltonian model which accounts for the helicoidal geometry. Computation of melting profiles by the path integral method suggests that stacking anharmonicity stabilizes the double helix against thermal disruption of the hydrogen bonds. Twisting is essential in the model to capture the importance of nonlinear effects on the thermodynamical properties. In a ladder model with zero twist, anharmonic stacking scarcely affects the thermodynamics. Moderately untwisted helices, with respect to the equilibrium conformation, show an energetic advantage against the overtwisted ones. Accordingly moderately untwisted helices better sustain local fluctuational openings and make more unlikely the thermally driven complete strand separation.
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Affiliation(s)
- Marco Zoli
- School of Science and Technology-CNISM, University of Camerino, Camerino, Italy.
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