1
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Ohkuma T, Hagita K, Murashima T, Deguchi T. Miscibility and exchange chemical potential of ring polymers in symmetric ring-ring blends. SOFT MATTER 2023; 19:3818-3827. [PMID: 37191220 DOI: 10.1039/d3sm00108c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Generally, differences of polymer topologies may affect polymer miscibility even with the same repeated units. In this study, the topological effect of ring polymers on miscibility was investigated by comparing symmetric ring-ring and linear-linear polymer blends. To elucidate the topological effect of ring polymers on mixing free energy, the exchange chemical potential of binary blends was numerically evaluated as a function of composition ϕ by performing semi-grand canonical Monte Carlo and molecular dynamics simulations of a bead-spring model. For ring-ring blends, an effective miscibility parameter was evaluated by comparing the exchange chemical potential with that of the Flory-Huggins model for linear-linear polymer blends. It was confirmed that in the mixed states satisfying χN > 0, ring-ring blends are more miscible and stable than the linear-linear blends with the same molecular weight. Furthermore, we investigated finite molecular weight dependence on the miscibility parameter, which reflected the statistical probability of interchain interactions in the blends. The simulation results revealed that the molecular weight dependence on the miscibility parameter was smaller in ring-ring blends. The effect of the ring polymers on miscibility was verified to be consistent with the change in the interchain radial distribution function. In ring-ring blends, it was indicated that the topology affected miscibility by reducing the effect of the direct interaction between the components of the blends.
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Affiliation(s)
- Takahiro Ohkuma
- Digital Engineering Division, Bridgestone Corporation, Kodaira, 187-8531, Japan.
| | - Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20, Hashirimizu, Yokosuka, 239-8686, Japan
| | - Takahiro Murashima
- Department of Physics, Tohoku University, 6-3, Aramaki-aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Tetsuo Deguchi
- Department of Physics, Faculty of Core Research, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan
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2
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Hagita K, Murashima T, Sakata N, Shimokawa K, Deguchi T, Uehara E, Fujiwara S. Molecular Dynamics of Topological Barriers on the Crystallization Behavior of Ring Polyethylene Melts with Trefoil Knots. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20, Hashirimizu, Yokosuka239-8686, Japan
| | - Takahiro Murashima
- Department of Physics, Tohoku University, 6-3, Aramaki-aza-Aoba, Aoba-ku, Sendai980-8578, Japan
| | - Naoki Sakata
- Department of Mathematics, Saitama University, 255, Shimo-Okubo, Sakura-ku, Saitama338-8570, Japan
- Department of Physics, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo112-8610, Japan
| | - Koya Shimokawa
- Department of Mathematics, Saitama University, 255, Shimo-Okubo, Sakura-ku, Saitama338-8570, Japan
- Department of Mathematics, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo112-8610, Japan
| | - Tetsuo Deguchi
- Department of Physics, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo112-8610, Japan
| | - Erica Uehara
- Department of Physics, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo112-8610, Japan
| | - Susumu Fujiwara
- Faculty of Materials Science and Engineering, Kyoto Institute of Technology, Matsugasaki,
Sakyo-ku, Kyoto606-8585, Japan
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3
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Nie X, Xiong C, Zhou X, Liu Y. Phase transition of DNA knotting in spherical space. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:385101. [PMID: 35820412 DOI: 10.1088/1361-648x/ac808f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Knots have been discovered in various biological systems, such as DNA. The knotting probability of DNA in free space depends non-monotonically on its bending rigidity and has a prominent peak. The current work aims to understand the underlying mechanism of the non-monotonic dependence of DNA knotting probability on bending rigidity. Monte Carlo simulations are performed on a closed DNA molecule confined in spherical space described by a worm-like chain model and a flexible kink model, respectively. The closed DNA's contour length and the spherical space radius both increase knotting probability, but also alter the unimodal dependence of knotting probability on bending rigidity. This is generalized using universal phase diagrams based on the two models. Under the flexible kink model, the total knotting probability of closed DNA is obviously increased at a relatively high excited energy. This supports the expectation that the entropy effect of knot size favours knot formation at a relatively low bending rigidity. In a given spherical space, the increasing contour length of closed DNA described by the worm-like chain model results in a visible shift in the knotting probability distribution. At the same time, the gyration radius of non-trivial closed DNA becomes comparable to that of trivial closed DNA, so that their ratio is not anti-correlated with average knot length. For closed DNA of various contour lengths, the relationship between average knot length and bending rigidity has a universal behaviour: the average knot length decreases to a local minimum at a bending rigidity of ∼5 and then gradually increases to a constant value. The existence of the local minimum is determined by the cut-off distance in repulsive Lennard-Jones potential. The bending rigidity corresponding to the beginning of the constant average knot length is consistent with that at the peak in the knotting distribution. At this point, the knot-size effect balances with the fragment free-energy effect and, at an even greater bending rigidity, knot length breathes around the average knot length value.
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Affiliation(s)
- Xiaolin Nie
- School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550025, People's Republic of China
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
| | - Caiyun Xiong
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
| | - Xun Zhou
- School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550025, People's Republic of China
| | - Yanhui Liu
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, Guizhou University, Guiyang 550025, People's Republic of China
- Kechuang Industrial Development Company Limited, Gui'an New Area, Guiyang 550025, People's Republic of China
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4
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Michieletto D, Fosado YAG, Melas E, Baiesi M, Tubiana L, Orlandini E. Dynamic and facilitated binding of topoisomerase accelerates topological relaxation. Nucleic Acids Res 2022; 50:4659-4668. [PMID: 35474478 PMCID: PMC9071436 DOI: 10.1093/nar/gkac260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 03/28/2022] [Accepted: 04/21/2022] [Indexed: 12/24/2022] Open
Abstract
How type 2 Topoisomerase (TopoII) proteins relax and simplify the topology of DNA molecules is one of the most intriguing open questions in genome and DNA biophysics. Most of the existing models neglect the dynamics of TopoII which is expected of proteins searching their targets via facilitated diffusion. Here, we show that dynamic binding of TopoII speeds up the topological relaxation of knotted substrates by enhancing the search of the knotted arc. Intriguingly, this in turn implies that the timescale of topological relaxation is virtually independent of the substrate length. We then discover that considering binding biases due to facilitated diffusion on looped substrates steers the sampling of the topological space closer to the boundaries between different topoisomers yielding an optimally fast topological relaxation. We discuss our findings in the context of topological simplification in vitro and in vivo.
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Affiliation(s)
| | | | - Elias Melas
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - Marco Baiesi
- Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy,INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy
| | - Luca Tubiana
- Physics Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy,INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, I-38123 Trento, Italy,Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Enzo Orlandini
- Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy,INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy
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5
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Roca J, Dyson S, Segura J, Valdés A, Martínez-García B. Keeping intracellular DNA untangled: A new role for condensin? Bioessays 2021; 44:e2100187. [PMID: 34761394 DOI: 10.1002/bies.202100187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/25/2022]
Abstract
The DNA-passage activity of topoisomerase II accidentally produces DNA knots and interlinks within and between chromatin fibers. Fortunately, these unwanted DNA entanglements are actively removed by some mechanism. Here we present an outline on DNA knot formation and discuss recent studies that have investigated how intracellular DNA knots are removed. First, although topoisomerase II is able to minimize DNA entanglements in vitro to below equilibrium values, it is unclear whether such capacity performs equally in vivo in chromatinized DNA. Second, DNA supercoiling could bias topoisomerase II to untangle the DNA. However, experimental evidence indicates that transcriptional supercoiling of intracellular DNA boosts knot formation. Last, cohesin and condensin could tighten DNA entanglements via DNA loop extrusion (LE) and force their dissolution by topoisomerase II. Recent observations indicate that condensin activity promotes the removal of DNA knots during interphase and mitosis. This activity might facilitate the spatial organization and dynamics of chromatin.
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Affiliation(s)
- Joaquim Roca
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Silvia Dyson
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Joana Segura
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Antonio Valdés
- Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Belén Martínez-García
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
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6
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Rusková R, Račko D. Channels with Helical Modulation Display Stereospecific Sensitivity for Chiral Superstructures. Polymers (Basel) 2021; 13:3726. [PMID: 34771282 PMCID: PMC8588256 DOI: 10.3390/polym13213726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/23/2021] [Accepted: 10/23/2021] [Indexed: 01/03/2023] Open
Abstract
By means of coarse-grained molecular dynamics simulations, we explore chiral sensitivity of confining spaces modelled as helical channels to chiral superstructures represented by polymer knots. The simulations show that helical channels exhibit stereosensitivity to chiral knots localized on linear chains by effect of external pulling force and also to knots embedded on circular chains. The magnitude of the stereoselective effect is stronger for torus knots, the effect is weaker in the case of twist knots, and amphichiral knots do exhibit no chiral effects. The magnitude of the effect can be tuned by the so-far investigated radius of the helix, the pitch of the helix and the strength of the pulling force. The model is aimed to simulate and address a range of practical situations that may occur in experimental settings such as designing of nanotechnological devices for the detection of topological state of molecules, preparation of new gels with tailor made stereoselective properties, or diffusion of knotted DNA in biological conditions.
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Affiliation(s)
- Renáta Rusková
- Polymer Institute, Slovak Academy of Sciences, Dúbravská Cesta 3, 84541 Bratislava, Slovakia;
- Department of Plastics, Rubber and Fibres (IPM FCFT), Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 81237 Bratislava, Slovakia
| | - Dušan Račko
- Polymer Institute, Slovak Academy of Sciences, Dúbravská Cesta 3, 84541 Bratislava, Slovakia;
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7
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Tsutsui M, Yokota K, Arima A, Washio T, Baba Y, Kawai T. Detecting Single Molecule Deoxyribonucleic Acid in a Cell Using a Three-Dimensionally Integrated Nanopore. SMALL METHODS 2021; 5:e2100542. [PMID: 34928053 DOI: 10.1002/smtd.202100542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/11/2021] [Indexed: 06/14/2023]
Abstract
Amplification-free genome analysis can revolutionize biology and medicine by uncovering genetic variations among individuals. Here, the authors report on a 3D-integrated nanopore for electrolysis to in situ detection of single-molecule DNA in a cell by ionic current measurements. It consists of a SiO2 multipore sheet and a SiNx nanopore membrane stacked vertically on a Si wafer. Single cell lysis is demonstrated by 106 V m-1 -level electrostatic field focused at the multinanopore. The intracellular molecules are then directly detected as they move through a sensing zone, wherein the authors find telegraphic current signatures reflecting folding degrees of freedom of the millimeter-long polynucleotides threaded through the SiNx nanopore. The present device concept may enable on-chip single-molecule sequencing to multi-omics analyses at a single-cell level.
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Affiliation(s)
- Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa, 761-0395, Japan
| | - Akihide Arima
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Institute of Nano-Life-Systems, Nagoya, Aichi, 464-8603, Japan
| | - Takashi Washio
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Yoshinobu Baba
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Institute of Nano-Life-Systems, Nagoya, Aichi, 464-8603, Japan
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Institute of Nano-Life-Systems, Nagoya, Aichi, 464-8603, Japan
- Institute of Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba, 263-8555, Japan
| | - Tomoji Kawai
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
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8
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Li Q, Apostolidou D, Marszalek PE. Reconstruction of mechanical unfolding and refolding pathways of proteins with atomic force spectroscopy and computer simulations. Methods 2021; 197:39-53. [PMID: 34020035 DOI: 10.1016/j.ymeth.2021.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/14/2021] [Accepted: 05/15/2021] [Indexed: 12/29/2022] Open
Abstract
Most proteins in proteomes are large, typically consist of more than one domain and are structurally complex. This often makes studying their mechanical unfolding pathways challenging. Proteins composed of tandem repeat domains are a subgroup of multi-domain proteins that, when stretched, display a saw-tooth pattern in their mechanical unfolding force extension profiles due to their repetitive structure. However, the assignment of force peaks to specific repeats undergoing mechanical unraveling is complicated because all repeats are similar and they interact with their neighbors and form a contiguous tertiary structure. Here, we describe in detail a combination of experimental and computational single-molecule force spectroscopy methods that proved useful for examining the mechanical unfolding and refolding pathways of ankyrin repeat proteins. Specifically, we explain and delineate the use of atomic force microscope-based single molecule force spectroscopy (SMFS) to record the mechanical unfolding behavior of ankyrin repeat proteins and capture their unusually strong refolding propensity that is responsible for generating impressive refolding force peaks. We also describe Coarse Grain Steered Molecular Dynamic (CG-SMD) simulations which complement the experimental observations and provide insights in understanding the unfolding and refolding of these proteins. In addition, we advocate the use of novel coiled-coils-based mechanical polypeptide probes which we developed to demonstrate the vectorial character of folding and refolding of these repeat proteins. The combination of AFM-based SMFS on native and CC-equipped proteins with CG-SMD simulations is powerful not only for ankyrin repeat polypeptides, but also for other repeat proteins and more generally to various multidomain, non-repetitive proteins with complex topologies.
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Affiliation(s)
- Qing Li
- Department of Mechanical Engineering and Materials Science, Duke University, 27708 Durham, NC, United States
| | - Dimitra Apostolidou
- Department of Mechanical Engineering and Materials Science, Duke University, 27708 Durham, NC, United States
| | - Piotr E Marszalek
- Department of Mechanical Engineering and Materials Science, Duke University, 27708 Durham, NC, United States.
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9
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Scalvini B, Sheikhhassani V, Woodard J, Aupič J, Dame RT, Jerala R, Mashaghi A. Topology of Folded Molecular Chains: From Single Biomolecules to Engineered Origami. TRENDS IN CHEMISTRY 2020. [DOI: 10.1016/j.trechm.2020.04.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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10
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Valdés A, Coronel L, Martínez-García B, Segura J, Dyson S, Díaz-Ingelmo O, Micheletti C, Roca J. Transcriptional supercoiling boosts topoisomerase II-mediated knotting of intracellular DNA. Nucleic Acids Res 2020; 47:6946-6955. [PMID: 31165864 PMCID: PMC6649788 DOI: 10.1093/nar/gkz491] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/09/2019] [Accepted: 05/22/2019] [Indexed: 12/04/2022] Open
Abstract
Recent studies have revealed that the DNA cross-inversion mechanism of topoisomerase II (topo II) not only removes DNA supercoils and DNA replication intertwines, but also produces small amounts of DNA knots within the clusters of nucleosomes that conform to eukaryotic chromatin. Here, we examine how transcriptional supercoiling of intracellular DNA affects the occurrence of these knots. We show that although (−) supercoiling does not change the basal DNA knotting probability, (+) supercoiling of DNA generated in front of the transcribing complexes increases DNA knot formation over 25-fold. The increase of topo II-mediated DNA knotting occurs both upon accumulation of (+) supercoiling in topoisomerase-deficient cells and during normal transcriptional supercoiling of DNA in TOP1 TOP2 cells. We also show that the high knotting probability (Pkn ≥ 0.5) of (+) supercoiled DNA reflects a 5-fold volume compaction of the nucleosomal fibers in vivo. Our findings indicate that topo II-mediated DNA knotting could be inherent to transcriptional supercoiling of DNA and other chromatin condensation processes and establish, therefore, a new crucial role of topoisomerase II in resetting the knotting–unknotting homeostasis of DNA during chromatin dynamics.
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Affiliation(s)
- Antonio Valdés
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
| | - Lucia Coronel
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - Belén Martínez-García
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
| | - Joana Segura
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
| | - Sílvia Dyson
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
| | - Ofelia Díaz-Ingelmo
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
| | - Cristian Micheletti
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - Joaquim Roca
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona 08028, Spain
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11
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Schvartzman JB, Hernández P, Krimer DB, Dorier J, Stasiak A. Closing the DNA replication cycle: from simple circular molecules to supercoiled and knotted DNA catenanes. Nucleic Acids Res 2019; 47:7182-7198. [PMID: 31276584 PMCID: PMC6698734 DOI: 10.1093/nar/gkz586] [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: 04/30/2019] [Revised: 06/20/2019] [Accepted: 07/02/2019] [Indexed: 01/28/2023] Open
Abstract
Due to helical structure of DNA, massive amounts of positive supercoils are constantly introduced ahead of each replication fork. Positive supercoiling inhibits progression of replication forks but various mechanisms evolved that permit very efficient relaxation of that positive supercoiling. Some of these mechanisms lead to interesting topological situations where DNA supercoiling, catenation and knotting coexist and influence each other in DNA molecules being replicated. Here, we first review fundamental aspects of DNA supercoiling, catenation and knotting when these qualitatively different topological states do not coexist in the same circular DNA but also when they are present at the same time in replicating DNA molecules. We also review differences between eukaryotic and prokaryotic cellular strategies that permit relaxation of positive supercoiling arising ahead of the replication forks. We end our review by discussing very recent studies giving a long-sought answer to the question of how slow DNA topoisomerases capable of relaxing just a few positive supercoils per second can counteract the introduction of hundreds of positive supercoils per second ahead of advancing replication forks.
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Affiliation(s)
- Jorge B Schvartzman
- Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Pablo Hernández
- Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Dora B Krimer
- Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Julien Dorier
- SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Andrzej Stasiak
- SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland.,Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
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12
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Kumar Sharma R, Agrawal I, Dai L, Doyle PS, Garaj S. Complex DNA knots detected with a nanopore sensor. Nat Commun 2019; 10:4473. [PMID: 31578328 PMCID: PMC6775256 DOI: 10.1038/s41467-019-12358-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 08/27/2019] [Indexed: 01/15/2023] Open
Abstract
Equilibrium knots are common in biological polymers-their prevalence, size distribution, structure, and dynamics have been extensively studied, with implications to fundamental biological processes and DNA sequencing technologies. Nanopore microscopy is a high-throughput single-molecule technique capable of detecting the shape of biopolymers, including DNA knots. Here we demonstrate nanopore sensors that map the equilibrium structure of DNA knots, without spurious knot tightening and sliding. We show the occurrence of both tight and loose knots, reconciling previous contradictory results from different experimental techniques. We evidence the occurrence of two quantitatively different modes of knot translocation through the nanopores, involving very different tension forces. With large statistics, we explore the complex knots and, for the first time, reveal the existence of rare composite knots. We use parametrized complexity, in concert with simulations, to test the theoretical assumptions of the models, further asserting the relevance of nanopores in future investigation of knots.
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Affiliation(s)
- Rajesh Kumar Sharma
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
- Singapore-MIT Alliance for Research and Technology Centre, 1 CREATE Way, Singapore, 138602, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Ishita Agrawal
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Liang Dai
- Department of Physics, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Patrick S Doyle
- Singapore-MIT Alliance for Research and Technology Centre, 1 CREATE Way, Singapore, 138602, Singapore.
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA.
| | - Slaven Garaj
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore.
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore.
- Department of Physics, National University of Singapore, Singapore, Science Drive 3, Singapore, 117551, Singapore.
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13
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Niewieczerzał S, Sulkowska JI. Supercoiling in a Protein Increases its Stability. PHYSICAL REVIEW LETTERS 2019; 123:138102. [PMID: 31697559 DOI: 10.1103/physrevlett.123.138102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Indexed: 06/10/2023]
Abstract
The supercoiling motif is the most complex type of nontrivial topology found in proteins with at least one disulfide bond and, to the best of our knowledge, it has not been studied before. We show that a protein from extremophilic species with such a motif can fold; however, the supercoiling changes a smooth landscape observed in reduced conditions into a two-state folding process in the oxidative conditions, with a deep intermediate state. The protein takes advantage of the hairpinlike motif to overcome the topological barrier and thus to supercoil. We find that the depth of the supercoiling motif, i.e., the length of the threaded terminus, has a crucial impact on the folding rates of the studied protein. We show that fluctuations of the minimal surface area can be used to measure local stability, and we find that supercoiling introduces stability into the protein. We suggest that the supercoiling motif enables the studied protein to live in physically extreme conditions, which are detrimental to most life on Earth.
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Affiliation(s)
- Szymon Niewieczerzał
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Joanna I Sulkowska
- Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
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14
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Ziraldo R, Hanke A, Levene SD. Kinetic pathways of topology simplification by Type-II topoisomerases in knotted supercoiled DNA. Nucleic Acids Res 2019; 47:69-84. [PMID: 30476194 PMCID: PMC6326819 DOI: 10.1093/nar/gky1174] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/02/2018] [Indexed: 11/13/2022] Open
Abstract
The topological state of covalently closed, double-stranded DNA is defined by the knot type $K$ and the linking-number difference $\Delta Lk$ relative to unknotted relaxed DNA. DNA topoisomerases are essential enzymes that control the topology of DNA in all cells. In particular, type-II topoisomerases change both $K$ and $\Delta Lk$ by a duplex-strand-passage mechanism and have been shown to simplify the topology of DNA to levels below thermal equilibrium at the expense of ATP hydrolysis. It remains a key question how small enzymes are able to preferentially select strand passages that result in topology simplification in much larger DNA molecules. Using numerical simulations, we consider the non-equilibrium dynamics of transitions between topological states $(K,\Delta Lk)$ in DNA induced by type-II topoisomerases. For a biological process that delivers DNA molecules in a given topological state $(K,\Delta Lk)$ at a constant rate we fully characterize the pathways of topology simplification by type-II topoisomerases in terms of stationary probability distributions and probability currents on the network of topological states $(K,\Delta Lk)$. In particular, we observe that type-II topoisomerase activity is significantly enhanced in DNA molecules that maintain a supercoiled state with constant torsional tension. This is relevant for bacterial cells in which torsional tension is maintained by enzyme-dependent homeostatic mechanisms such as DNA-gyrase activity.
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Affiliation(s)
- Riccardo Ziraldo
- Department of Bioengineering, University of Texas at Dallas, TX 75080, USA
| | - Andreas Hanke
- Department of Physics and Astronomy, University of Texas Rio Grande Valley, Brownsville, TX 78520, USA
| | - Stephen D Levene
- Department of Bioengineering, University of Texas at Dallas, TX 75080, USA.,Department of Biological Sciences, University of Texas at Dallas, Richardson, TX 75080, USA.,Department of Physics, University of Texas at Dallas, Richardson, TX 75080, USA
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15
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Valdés A, Segura J, Dyson S, Martínez-García B, Roca J. DNA knots occur in intracellular chromatin. Nucleic Acids Res 2019; 46:650-660. [PMID: 29149297 PMCID: PMC5778459 DOI: 10.1093/nar/gkx1137] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/28/2017] [Indexed: 01/12/2023] Open
Abstract
In vivo DNA molecules are narrowly folded within chromatin fibers and self-interacting chromatin domains. Therefore, intra-molecular DNA entanglements (knots) might occur via DNA strand passage activity of topoisomerase II. Here, we assessed the presence of such DNA knots in a variety of yeast circular minichromosomes. We found that small steady state fractions of DNA knots are common in intracellular chromatin. These knots occur irrespective of DNA replication and cell proliferation, though their abundance is reduced during DNA transcription. We found also that in vivo DNA knotting probability does not scale proportionately with chromatin length: it reaches a value of ∼0.025 in domains of ∼20 nucleosomes but tends to level off in longer chromatin fibers. These figures suggest that, while high flexibility of nucleosomal fibers and clustering of nearby nucleosomes facilitate DNA knotting locally, some mechanism minimizes the scaling of DNA knot formation throughout intracellular chromatin. We postulate that regulation of topoisomerase II activity and the fractal architecture of chromatin might be crucial to prevent a potentially massive and harmful self-entanglement of DNA molecules in vivo.
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Affiliation(s)
- Antonio Valdés
- Molecular Biology Institute of Barcelona (IBMB); Spanish National Research Council (CSIC); Barcelona 08028; Spain
| | - Joana Segura
- Molecular Biology Institute of Barcelona (IBMB); Spanish National Research Council (CSIC); Barcelona 08028; Spain
| | - Sílvia Dyson
- Molecular Biology Institute of Barcelona (IBMB); Spanish National Research Council (CSIC); Barcelona 08028; Spain
| | - Belén Martínez-García
- Molecular Biology Institute of Barcelona (IBMB); Spanish National Research Council (CSIC); Barcelona 08028; Spain
| | - Joaquim Roca
- Molecular Biology Institute of Barcelona (IBMB); Spanish National Research Council (CSIC); Barcelona 08028; Spain
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16
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Suma A, Poppleton E, Matthies M, Šulc P, Romano F, Louis AA, Doye JPK, Micheletti C, Rovigatti L. TacoxDNA: A user-friendly web server for simulations of complex DNA structures, from single strands to origami. J Comput Chem 2019; 40:2586-2595. [PMID: 31301183 DOI: 10.1002/jcc.26029] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/20/2019] [Accepted: 06/22/2019] [Indexed: 12/11/2022]
Abstract
Simulations of nucleic acids at different levels of structural details are increasingly used to complement and interpret experiments in different fields, from biophysics to medicine and materials science. However, the various structural models currently available for DNA and RNA and their accompanying suites of computational tools can be very rarely used in a synergistic fashion. The tacoxDNA webserver and standalone software package presented here are a step toward a long-sought interoperability of nucleic acids models. The webserver offers a simple interface for converting various common input formats of DNA structures and setting up molecular dynamics (MD) simulations. Users can, for instance, design DNA rings with different topologies, such as knots, with and without supercoiling, by simply providing an XYZ coordinate file of the DNA centre-line. More complex DNA geometries, as designable in the cadnano, CanDo and Tiamat tools, can also be converted to all-atom or oxDNA representations, which can then be used to run MD simulations. Though the latter are currently geared toward the native and LAMMPS oxDNA representations, the open-source package is designed to be further expandable. TacoxDNA is available at http://tacoxdna.sissa.it. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Antonio Suma
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122.,SISSA-Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea, 265, 34136, Trieste, Italy
| | - Erik Poppleton
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, 1001, South McAllister Avenue, Tempe, Arizona 85281
| | - Michael Matthies
- Center for Advancing Electronics Dresden (cfaed), Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Petr Šulc
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, 1001, South McAllister Avenue, Tempe, Arizona 85281
| | - Flavio Romano
- Dipartimento di Scienze Molecolari e Nanosistemi, Universitá Ca Foscari di Venezia, Via Torino, 155, 30172, Venezia Mestre, Italy
| | - Ard A Louis
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP, UK
| | - Jonathan P K Doye
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Cristian Micheletti
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea, 265, 34136, Trieste, Italy
| | - Lorenzo Rovigatti
- Dipartimento di Fisica, Sapienza Universitá di Roma, Piazzale A. Moro, 2, 00185, Rome, Italy.,CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Rome, Italy
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17
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Orlandini E, Marenduzzo D, Michieletto D. Synergy of topoisomerase and structural-maintenance-of-chromosomes proteins creates a universal pathway to simplify genome topology. Proc Natl Acad Sci U S A 2019; 116:8149-8154. [PMID: 30962387 PMCID: PMC6486742 DOI: 10.1073/pnas.1815394116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Topological entanglements severely interfere with important biological processes. For this reason, genomes must be kept unknotted and unlinked during most of a cell cycle. Type II topoisomerase (TopoII) enzymes play an important role in this process but the precise mechanisms yielding systematic disentanglement of DNA in vivo are not clear. Here we report computational evidence that structural-maintenance-of-chromosomes (SMC) proteins-such as cohesins and condensins-can cooperate with TopoII to establish a synergistic mechanism to resolve topological entanglements. SMC-driven loop extrusion (or diffusion) induces the spatial localization of essential crossings, in turn catalyzing the simplification of knots and links by TopoII enzymes even in crowded and confined conditions. The mechanism we uncover is universal in that it does not qualitatively depend on the specific substrate, whether DNA or chromatin, or on SMC processivity; we thus argue that this synergy may be at work across organisms and throughout the cell cycle.
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Affiliation(s)
- Enzo Orlandini
- Dipartimento di Fisica e Astronomia "Galileo Galilei," Sezione Istituto Nazionale di Fisica Nucleare, Università degli Studi di Padova, I-35131 Padova, Italy
| | - Davide Marenduzzo
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - Davide Michieletto
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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18
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Najafi S. Topological entanglement of interlocked knotted-unknotted polymer rings. SOFT MATTER 2019; 15:1916-1921. [PMID: 30734820 DOI: 10.1039/c8sm02530d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Topological entanglements in biopolymers could drive them to certain internal statics and dynamics with important implications for biological functions. In this study, by means of molecular dynamics simulations, we demonstrate that the minimal crossing pattern of a braid plays a major role in its structural and dynamical properties; the braid consists of a knotted ring and an interlocked entwined unknotted polymer ring. In particular, we show that depending on the bending rigidity of the chains, the conformational energy of the braid can be either lower or higher than the unlocked polymer rings. Additionally, we find that a non-identical crossing pattern in the braid could distinctly enforce concerted internal conformational fluctuations between the interlocked rings.
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Affiliation(s)
- Saeed Najafi
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
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19
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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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20
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A ring-polymer model shows how macromolecular crowding controls chromosome-arm organization in Escherichia coli. Sci Rep 2017; 7:11896. [PMID: 28928399 PMCID: PMC5605704 DOI: 10.1038/s41598-017-10421-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/08/2017] [Indexed: 12/21/2022] Open
Abstract
Macromolecular crowding influences various cellular processes such as macromolecular association and transcription, and is a key determinant of chromosome organization in bacteria. The entropy of crowders favors compaction of long chain molecules such as chromosomes. To what extent is the circular bacterial chromosome, often viewed as consisting of “two arms”, organized entropically by crowding? Using computer simulations, we examine how a ring polymer is organized in a crowded and cylindrically-confined space, as a coarse-grained bacterial chromosome. Our results suggest that in a wide parameter range of biological relevance crowding is essential for separating the two arms in the way observed with Escherichia coli chromosomes at fast-growth rates, in addition to maintaining the chromosome in an organized collapsed state. Under different conditions, however, the ring polymer is centrally condensed or adsorbed onto the cylindrical wall with the two arms laterally collapsed onto each other. We discuss the relevance of our results to chromosome-membrane interactions.
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21
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Topological transformations in proteins: effects of heating and proximity of an interface. Sci Rep 2017; 7:39851. [PMID: 28051124 PMCID: PMC5209716 DOI: 10.1038/srep39851] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 11/28/2016] [Indexed: 01/04/2023] Open
Abstract
Using a structure-based coarse-grained model of proteins, we study the mechanism of unfolding of knotted proteins through heating. We find that the dominant mechanisms of unfolding depend on the temperature applied and are generally distinct from those identified for folding at its optimal temperature. In particular, for shallowly knotted proteins, folding usually involves formation of two loops whereas unfolding through high-temperature heating is dominated by untying of single loops. Untying the knots is found to generally precede unfolding unless the protein is deeply knotted and the heating temperature exceeds a threshold value. We then use a phenomenological model of the air-water interface to show that such an interface can untie shallow knots, but it can also make knots in proteins that are natively unknotted.
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22
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Model of DNA topology simplification has come full (supercoiled) circle after two decades of research. Phys Life Rev 2016; 18:154-157. [DOI: 10.1016/j.plrev.2016.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 11/23/2022]
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23
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Rieger FC, Virnau P. A Monte Carlo Study of Knots in Long Double-Stranded DNA Chains. PLoS Comput Biol 2016; 12:e1005029. [PMID: 27631891 PMCID: PMC5025000 DOI: 10.1371/journal.pcbi.1005029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/21/2016] [Indexed: 11/26/2022] Open
Abstract
We determine knotting probabilities and typical sizes of knots in double-stranded DNA for chains of up to half a million base pairs with computer simulations of a coarse-grained bead-stick model: Single trefoil knots and composite knots which include at least one trefoil as a prime factor are shown to be common in DNA chains exceeding 250,000 base pairs, assuming physiologically relevant salt conditions. The analysis is motivated by the emergence of DNA nanopore sequencing technology, as knots are a potential cause of erroneous nucleotide reads in nanopore sequencing devices and may severely limit read lengths in the foreseeable future. Even though our coarse-grained model is only based on experimental knotting probabilities of short DNA strands, it reproduces the correct persistence length of DNA. This indicates that knots are not only a fine gauge for structural properties, but a promising tool for the design of polymer models.
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Affiliation(s)
- Florian C. Rieger
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
- Graduate School Materials Science in Mainz, Mainz, Germany
| | - Peter Virnau
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
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24
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Rawdon EJ, Dorier J, Racko D, Millett KC, Stasiak A. How topoisomerase IV can efficiently unknot and decatenate negatively supercoiled DNA molecules without causing their torsional relaxation. Nucleic Acids Res 2016; 44:4528-38. [PMID: 27106058 PMCID: PMC4889953 DOI: 10.1093/nar/gkw311] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/12/2016] [Indexed: 12/13/2022] Open
Abstract
Freshly replicated DNA molecules initially form multiply interlinked right-handed catenanes. In bacteria, these catenated molecules become supercoiled by DNA gyrase before they undergo a complete decatenation by topoisomerase IV (Topo IV). Topo IV is also involved in the unknotting of supercoiled DNA molecules. Using Metropolis Monte Carlo simulations, we investigate the shapes of supercoiled DNA molecules that are either knotted or catenated. We are especially interested in understanding how Topo IV can unknot right-handed knots and decatenate right-handed catenanes without acting on right-handed plectonemes in negatively supercoiled DNA molecules. To this end, we investigate how the topological consequences of intersegmental passages depend on the geometry of the DNA-DNA juxtapositions at which these passages occur. We observe that there are interesting differences between the geometries of DNA-DNA juxtapositions in the interwound portions and in the knotted or catenated portions of the studied molecules. In particular, in negatively supercoiled, multiply interlinked, right-handed catenanes, we detect specific regions where DNA segments belonging to two freshly replicated sister DNA molecules form left-handed crossings. We propose that, due to its geometrical preference to act on left-handed crossings, Topo IV can specifically unknot supercoiled DNA, as well as decatenate postreplicative catenanes, without causing their torsional relaxation.
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Affiliation(s)
- Eric J Rawdon
- Department of Mathematics, University of St. Thomas, Saint Paul, MN 55105, USA
| | - Julien Dorier
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland Vital-IT, SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Dusan Racko
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland Polymer Institute of the Slovak Academy of Sciences, 842 36 Bratislava, Slovakia
| | - Kenneth C Millett
- Department of Mathematics, University of California, Santa Barbara, CA 93106, USA
| | - Andrzej Stasiak
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
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25
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Liu Z, Chan HS. Consistent rationalization of type-2 topoisomerases' unknotting, decatenating, supercoil-relaxing actions and their scaling relation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:354103. [PMID: 26291958 DOI: 10.1088/0953-8984/27/35/354103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
How type-2 topoisomerases discern global topology from local properties of DNA is not known precisely but the hypothesis that the enzymes selectively pass double-helix strands at hook-like juxtapositions is promising. Building upon an investigation of unknotting and decatenating using an improved wormlike DNA model, here we focus primarily on the enzymes' action in narrowing the distribution of linking number (Lk) in supercoiled DNA. Consistent with experiments, with selective passage at a hooked juxtaposition, the simulated narrowing factor RLk diminishes with decreasing DNA circle size but approaches an asymptotic RLk ≈ 1.7-1.8 for circle size ≳3.5 kb. For the larger DNA circles, we found that (RLk - 1) ≈ 0.42log10RK ≈ 0.68log10RL and thus RK ≈ (RL)(1.6) holds for the computed RLk and knot and catenane reduction factors RK and RL attained by selective passage at different juxtaposition geometries. Remarkably, this general scaling relation is essentially identical to that observed experimentally for several type-2 topoisomerases from a variety of organisms, indicating that the different disentangling powers of the topoisomerases likely arise from variations in the hooked geometries they select. Taken together, our results suggest strongly that type-2 topoisomerases recognize not only the curvature of the G-segment but also that of the T-segment.
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Affiliation(s)
- Zhirong Liu
- College of Chemistry and Molecular Engineering, Center for Quantitative Biology, and Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People's Republic of China
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26
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Adenylylation of Gyrase and Topo IV by FicT Toxins Disrupts Bacterial DNA Topology. Cell Rep 2015; 12:1497-507. [PMID: 26299961 DOI: 10.1016/j.celrep.2015.07.056] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 07/21/2015] [Accepted: 07/27/2015] [Indexed: 01/10/2023] Open
Abstract
Toxin-antitoxin (TA) modules are ubiquitous molecular switches controlling bacterial growth via the release of toxins that inhibit cell proliferation. Most of these toxins interfere with protein translation, but a growing variety of other mechanisms hints at a diversity that is not yet fully appreciated. Here, we characterize a group of FIC domain proteins as toxins of the conserved and abundant FicTA family of TA modules, and we reveal that they act by suspending control of cellular DNA topology. We show that FicTs are enzymes that adenylylate DNA gyrase and topoisomerase IV, the essential bacterial type IIA topoisomerases, at their ATP-binding site. This modification inactivates both targets by blocking their ATPase activity, and, consequently, causes reversible growth arrest due to the knotting, catenation, and relaxation of cellular DNA. Our results give insight into the regulation of DNA topology and highlight the remarkable plasticity of FIC domain proteins.
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27
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Racko D, Benedetti F, Dorier J, Burnier Y, Stasiak A. Generation of supercoils in nicked and gapped DNA drives DNA unknotting and postreplicative decatenation. Nucleic Acids Res 2015; 43:7229-36. [PMID: 26150424 PMCID: PMC4551925 DOI: 10.1093/nar/gkv683] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/23/2015] [Indexed: 01/01/2023] Open
Abstract
Due to the helical structure of DNA the process of DNA replication is topologically complex. Freshly replicated DNA molecules are catenated with each other and are frequently knotted. For proper functioning of DNA it is necessary to remove all of these entanglements. This is done by DNA topoisomerases that pass DNA segments through each other. However, it has been a riddle how DNA topoisomerases select the sites of their action. In highly crowded DNA in living cells random passages between contacting segments would only increase the extent of entanglement. Using molecular dynamics simulations we observed that in actively supercoiled DNA molecules the entanglements resulting from DNA knotting or catenation spontaneously approach sites of nicks and gaps in the DNA. Type I topoisomerases, that preferentially act at sites of nick and gaps, are thus naturally provided with DNA–DNA juxtapositions where a passage results in an error-free DNA unknotting or DNA decatenation.
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Affiliation(s)
- Dusan Racko
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland SIB Swiss Institute of Bioinformatics, 1015-Lausanne, Switzerland Polymer Institute of the Slovak Academy of Sciences, 842 36 Bratislava, Slovakia
| | - Fabrizio Benedetti
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland SIB Swiss Institute of Bioinformatics, 1015-Lausanne, Switzerland
| | - Julien Dorier
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland Vital-IT, SIB Swiss Institute of Bioinformatics, 1015-Lausanne, Switzerland
| | - Yannis Burnier
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne (EPFL), 1015-Lausanne, Switzerland
| | - Andrzej Stasiak
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland SIB Swiss Institute of Bioinformatics, 1015-Lausanne, Switzerland
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28
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Cebrián J, Castán A, Martínez V, Kadomatsu-Hermosa MJ, Parra C, Fernández-Nestosa MJ, Schaerer C, Hernández P, Krimer DB, Schvartzman JB. Direct Evidence for the Formation of Precatenanes during DNA Replication. J Biol Chem 2015; 290:13725-35. [PMID: 25829493 PMCID: PMC4447951 DOI: 10.1074/jbc.m115.642272] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/30/2015] [Indexed: 11/06/2022] Open
Abstract
The dynamics of DNA topology during replication are still poorly understood. Bacterial plasmids are negatively supercoiled. This underwinding facilitates strand separation of the DNA duplex during replication. Leading the replisome, a DNA helicase separates the parental strands that are to be used as templates. This strand separation causes overwinding of the duplex ahead. If this overwinding persists, it would eventually impede fork progression. In bacteria, DNA gyrase and topoisomerase IV act ahead of the fork to keep DNA underwound. However, the processivity of the DNA helicase might overcome DNA gyrase and topoisomerase IV. It was proposed that the overwinding that builds up ahead of the fork could force it to swivel and diffuse this positive supercoiling behind the fork where topoisomerase IV would also act to maintain replicating the DNA underwound. Putative intertwining of sister duplexes in the replicated region are called precatenanes. Fork swiveling and the formation of precatenanes, however, are still questioned. Here, we used classical genetics and high resolution two-dimensional agarose gel electrophoresis to examine the torsional tension of replication intermediates of three bacterial plasmids with the fork stalled at different sites before termination. The results obtained indicated that precatenanes do form as replication progresses before termination.
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Affiliation(s)
- Jorge Cebrián
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Alicia Castán
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Víctor Martínez
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Maridian J Kadomatsu-Hermosa
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Cristina Parra
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - María José Fernández-Nestosa
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Christian Schaerer
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Pablo Hernández
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Dora B Krimer
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Jorge B Schvartzman
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
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Colomb W, Sarkar SK. Extracting physics of life at the molecular level: A review of single-molecule data analyses. Phys Life Rev 2015; 13:107-37. [PMID: 25660417 DOI: 10.1016/j.plrev.2015.01.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 12/31/2022]
Abstract
Studying individual biomolecules at the single-molecule level has proved very insightful recently. Single-molecule experiments allow us to probe both the equilibrium and nonequilibrium properties as well as make quantitative connections with ensemble experiments and equilibrium thermodynamics. However, it is important to be careful about the analysis of single-molecule data because of the noise present and the lack of theoretical framework for processes far away from equilibrium. Biomolecular motion, whether it is free in solution, on a substrate, or under force, involves thermal fluctuations in varying degrees, which makes the motion noisy. In addition, the noise from the experimental setup makes it even more complex. The details of biologically relevant interactions, conformational dynamics, and activities are hidden in the noisy single-molecule data. As such, extracting biological insights from noisy data is still an active area of research. In this review, we will focus on analyzing both fluorescence-based and force-based single-molecule experiments and gaining biological insights at the single-molecule level. Inherently nonequilibrium nature of biological processes will be highlighted. Simulated trajectories of biomolecular diffusion will be used to compare and validate various analysis techniques.
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Affiliation(s)
- Warren Colomb
- Department of Physics, Colorado School of Mines, Golden, CO 80401, United States
| | - Susanta K Sarkar
- Department of Physics, Colorado School of Mines, Golden, CO 80401, United States.
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30
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Brackley CA, Allan J, Keszenman-Pereyra D, Marenduzzo D. Topological constraints strongly affect chromatin reconstitution in silico. Nucleic Acids Res 2015; 43:63-73. [PMID: 25432958 PMCID: PMC4288149 DOI: 10.1093/nar/gku1085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022] Open
Abstract
The fundamental building block of chromatin, and of chromosomes, is the nucleosome, a composite material made up from DNA wrapped around a histone octamer. In this study we provide the first computer simulations of chromatin self-assembly, starting from DNA and histone proteins, and use these to understand the constraints which are imposed by the topology of DNA molecules on the creation of a polynucleosome chain. We take inspiration from the in vitro chromatin reconstitution protocols which are used in many experimental studies. Our simulations indicate that during self-assembly, nucleosomes can fall into a number of topological traps (or local folding defects), and this may eventually lead to the formation of disordered structures, characterised by nucleosome clustering. Remarkably though, by introducing the action of topological enzymes such as type I and II topoisomerase, most of these defects can be avoided and the result is an ordered 10-nm chromatin fibre. These findings provide new insight into the biophysics of chromatin formation, both in the context of reconstitution in vitro and in terms of the topological constraints which must be overcome during de novo nucleosome formation in vivo, e.g. following DNA replication or repair.
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Affiliation(s)
- C A Brackley
- SUPA, School of Physics & Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - J Allan
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - D Keszenman-Pereyra
- Edinburgh Genomics, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - D Marenduzzo
- SUPA, School of Physics & Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
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31
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Medalion S, Rabin Y. Effect of knots on binding of intercalators to DNA. J Chem Phys 2014; 140:205101. [DOI: 10.1063/1.4875804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
Bacteriophages initiate infection by releasing their double-stranded DNA into the cytosol of their bacterial host. However, what controls and sets the timescales of DNA ejection? Here we provide evidence from stochastic simulations which shows that the topology and organization of DNA packed inside the capsid plays a key role in determining these properties. Even with similar osmotic pressure pushing out the DNA, we find that spatially ordered DNA spools have a much lower effective friction than disordered entangled states. Such spools are only found when the tendency of nearby DNA strands to align locally is accounted for. This topological or conformational friction also depends on DNA knot type in the packing geometry and slows down or arrests the ejection of twist knots and very complex knots. We also find that the family of (2, 2k+1) torus knots unravel gradually by simplifying their topology in a stepwise fashion. Finally, an analysis of DNA trajectories inside the capsid shows that the knots formed throughout the ejection process mirror those found in gel electrophoresis experiments for viral DNA molecules extracted from the capsids.
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Abstract
DNA topology changes dynamically during DNA replication. Supercoiling, precatenation, catenation and knotting interplay throughout the process that is finely regulated by DNA topoisomerases. In the present article, we provide an overview of theoretical and experimental approaches to understand the interplay between various manifestations of topological constraints acting on replicating DNA molecules. Data discussed reveal that DNA entanglements (supercoils and catenanes) play an active role in preventing the formation of deleterious knots.
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34
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Kim N, Petingi L, Schlick T. Network Theory Tools for RNA Modeling. WSEAS TRANSACTIONS ON MATHEMATICS 2013; 9:941-955. [PMID: 25414570 PMCID: PMC4235620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An introduction into the usage of graph or network theory tools for the study of RNA molecules is presented. By using vertices and edges to define RNA secondary structures as tree and dual graphs, we can enumerate, predict, and design RNA topologies. Graph connectivity and associated Laplacian eigenvalues relate to biological properties of RNA and help understand RNA motifs as well as build, by computational design, various RNA target structures. Importantly, graph theoretical representations of RNAs reduce drastically the conformational space size and therefore simplify modeling and prediction tasks. Ongoing challenges remain regarding general RNA design, representation of RNA pseudoknots, and tertiary structure prediction. Thus, developments in network theory may help advance RNA biology.
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Affiliation(s)
- Namhee Kim
- New York University Department of Chemistry Courant Institute of Mathematical Sciences 251 Mercer Street New York, NY 10012, USA
| | - Louis Petingi
- College of Staten Island City University of New York Department of Computer Science 2800 Victory Boulevard Staten Island, NY 10314, USA
| | - Tamar Schlick
- New York University Department of Chemistry Courant Institute of Mathematical Sciences 251 Mercer Street New York, NY 10012, USA
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35
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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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36
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Crossing-sign discrimination and knot-reduction for a lattice model of strand passage. Biochem Soc Trans 2013; 41:576-81. [DOI: 10.1042/bst20120333] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
By performing strand-passages on DNA, type II topoisomerases are known to resolve topological constraints that impede normal cellular functions. The full details of this enzyme–DNA interaction mechanism are, however, not completely understood. To better understand this mechanism, researchers have proposed and studied a variety of random polygon models of enzyme-induced strand-passage. In the present article, we review results from one such model having the feature that it is amenable to combinatorial and asymptotic analysis (as polygon length goes to infinity). The polygons studied, called Θ-SAPs, are on the simple-cubic lattice and contain a specific strand-passage structure, called Θ, at a fixed site. Another feature of this model is the availability of Monte Carlo methods that facilitate the estimation of crossing-sign-dependent knot-transition probabilities. From such estimates, it has been possible to investigate how knot-reduction depends on the crossing-sign and the local juxtaposition geometry at the strand-passage site. A strong relationship between knot-reduction and a crossing-sign-dependent crossing-angle has been observed for this model. In the present article, we review these results and present heuristic geometrical arguments to explain this crossing-sign and angle-dependence. Finally, we discuss potential implications for other models of type II topoisomerase action on DNA.
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37
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López V, Martínez-Robles ML, Hernández P, Krimer DB, Schvartzman JB. Topo IV is the topoisomerase that knots and unknots sister duplexes during DNA replication. Nucleic Acids Res 2011; 40:3563-73. [PMID: 22187153 PMCID: PMC3333868 DOI: 10.1093/nar/gkr1237] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
DNA topology plays a crucial role in all living cells. In prokaryotes, negative supercoiling is required to initiate replication and either negative or positive supercoiling assists decatenation. The role of DNA knots, however, remains a mystery. Knots are very harmful for cells if not removed efficiently, but DNA molecules become knotted in vivo. If knots are deleterious, why then does DNA become knotted? Here, we used classical genetics, high-resolution 2D agarose gel electrophoresis and atomic force microscopy to show that topoisomerase IV (Topo IV), one of the two type-II DNA topoisomerases in bacteria, is responsible for the knotting and unknotting of sister duplexes during DNA replication. We propose that when progression of the replication forks is impaired, sister duplexes become loosely intertwined. Under these conditions, Topo IV inadvertently makes the strand passages that lead to the formation of knots and removes them later on to allow their correct segregation.
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Affiliation(s)
| | | | | | | | - Jorge B. Schvartzman
- *To whom correspondence should be addressed. Tel: +34 91 837 3112 (ext. 4232); Fax: +34 91 536 0432;
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38
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Alonso-Sarduy L, Roduit C, Dietler G, Kasas S. Human topoisomerase II-DNA interaction study by using atomic force microscopy. FEBS Lett 2011; 585:3139-45. [PMID: 21907712 DOI: 10.1016/j.febslet.2011.08.051] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 08/24/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022]
Abstract
Type II topoisomerases (Topo II) are unique enzymes that change the DNA topology by catalyzing the passage of two double-strands across each other by using the energy from ATP hydrolysis. In vitro, human Topo II relaxes positive supercoiled DNA around 10-fold faster than negative supercoiled DNA. By using atomic force microscopy (AFM) we found that human Topo II binds preferentially to DNA cross-overs. Around 50% of the DNA crossings, where Topo II was bound to, presented an angle in the range of 80-90°, suggesting a favored binding geometry in the chiral discrimination by Topo II. Our studies with AFM also helped us visualize the dynamics of the unknotting action of Topo II in knotted molecules.
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Affiliation(s)
- Livan Alonso-Sarduy
- Laboratoire de Physique de la Matière Vivante, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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