1
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Liu M, Pan H, Kaur P, Wang LJ, Jin M, Detwiler AC, Opresko PL, Tao YJ, Wang H, Riehn R. Assembly path dependence of telomeric DNA compaction by TRF1, TIN2, and SA1. Biophys J 2023; 122:1822-1832. [PMID: 37081787 PMCID: PMC10209029 DOI: 10.1016/j.bpj.2023.04.014] [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: 09/28/2022] [Revised: 03/10/2023] [Accepted: 04/12/2023] [Indexed: 04/22/2023] Open
Abstract
Telomeres, complexes of DNA and proteins, protect ends of linear chromosomes. In humans, the two shelterin proteins TRF1 and TIN2, along with cohesin subunit SA1, were proposed to mediate telomere cohesion. Although the ability of the TRF1-TIN2 and TRF1-SA1 systems to compact telomeric DNA by DNA-DNA bridging has been reported, the function of the full ternary TRF1-TIN2-SA1 system has not been explored in detail. Here, we quantify the compaction of nanochannel-stretched DNA by the ternary system, as well as its constituents, and obtain estimates of the relative impact of its constituents and their interactions. We find that TRF1, TIN2, and SA1 work synergistically to cause a compaction of the DNA substrate, and that maximal compaction occurs if all three proteins are present. By altering the sequence with which DNA substrates are exposed to proteins, we establish that compaction by TRF1 and TIN2 can proceed through binding of TRF1 to DNA, followed by compaction as TIN2 recognizes the previously bound TRF1. We further establish that SA1 alone can also lead to a compaction, and that compaction in a combined system of all three proteins can be understood as an additive effect of TRF1-TIN2 and SA1-based compaction. Atomic force microscopy of intermolecular aggregation confirms that a combination of TRF1, TIN2, and SA1 together drive strong intermolecular aggregation as it would be required during chromosome cohesion.
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Affiliation(s)
- Ming Liu
- Department of Physics, NC State University, Raleigh, North Carolina
| | - Hai Pan
- Department of Physics, NC State University, Raleigh, North Carolina
| | - Parminder Kaur
- Department of Physics, NC State University, Raleigh, North Carolina
| | - Lucia J Wang
- Department of Physics, NC State University, Raleigh, North Carolina
| | - Miao Jin
- Department of BioSciences, Rice University, Houston, Texas
| | - Ariana C Detwiler
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Yizhi Jane Tao
- Department of BioSciences, Rice University, Houston, Texas
| | - Hong Wang
- Department of Physics, NC State University, Raleigh, North Carolina
| | - Robert Riehn
- Department of Physics, NC State University, Raleigh, North Carolina.
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2
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Chen J, Sun L, Wang S, Tian F, Zhu H, Zhang R, Dai L. Crowding-induced polymer trapping in a channel. Phys Rev E 2021; 104:054502. [PMID: 34942690 DOI: 10.1103/physreve.104.054502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 10/20/2021] [Indexed: 11/07/2022]
Abstract
In this work, we report an intriguing phenomenon: crowding-induced polymer trapping in a channel. Using Langevin dynamics simulations and analytical calculations, we find that for a polymer confined in a channel, crowding particles can push a polymer into the channel corner through inducing an effective polymer-corner attraction due to the depletion effect. This phenomenon is referred to as polymer trapping. The occurrence of polymer trapping requires a minimum volume fraction of crowders, ϕ^{*}, which scales as ϕ^{*}∼(a_{c}/L_{p})^{1/3} for a_{c}≫a_{m} and ϕ^{*}∼(a_{c}/L_{p})^{1/3}(a_{c}/a_{m})^{1/2} for a_{c}≪a_{m}, where a_{c} is the crowder diameter, a_{m} is the monomer diameter, and L_{p} is the polymer persistence length. For DNA, ϕ^{*} is estimated to be around 0.25 for crowders with a_{c}=2nm. We find that ϕ^{*} also strongly depends on the shape of the channel cross section, and ϕ^{*} is much smaller for a triangle channel than a square channel. The polymer trapping leads to a nearly fully stretched polymer conformation along a channel corner, which may have practical applications, such as full stretching of DNA for the nanochannel-based genome mapping technology.
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Affiliation(s)
- Jialu Chen
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Liang Sun
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Simin Wang
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Fujia Tian
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Haoqi Zhu
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Ruiqin Zhang
- Department of Physics, City University of Hong Kong, Hong Kong, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong, China
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3
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Chen W, Wei S. Compressive deformations of ring polymers in a confining channel. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.124340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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4
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Bucci G, Gadelrab K, Spakowitz AJ. Free Energy and Dynamics of Annihilation of Topological Defects in Nanoconfined DNA. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Giovanna Bucci
- Robert Bosch LLC, 384 Santa Trinita Ave, Sunnyvale, California 94085, United States
| | - Karim Gadelrab
- Robert Bosch LLC, 1 Kendall Square, Suite 7-101, Cambridge, Massachusetts 02139, United States
| | - Andrew J. Spakowitz
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- Biophysics Program, Stanford University, Stanford, California 94305, United States
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5
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Milchev A, Binder K. Adsorption of Semiflexible Polymers in Cylindrical Tubes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11759-11770. [PMID: 34581575 DOI: 10.1021/acs.langmuir.1c01715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Conformations of wormlike chains in cylindrical pores with attractive walls are explored for varying pore radius and strength of the attractive wall potential by molecular dynamics simulations of a coarse-grained model. Local quantities such as the fraction of monomeric units bound to the surface and the bond-orientational order parameter as well as the radial density distribution are studied, as well as the global chain extensions parallel to the cylinder axis and perpendicular to the cylinder surface. A nonmonotonic convergence of these properties to their counterparts for adsorption on a planar substrate is observed due to the conflict between pore surface curvature and chain stiffness. Also the interpretation of partially adsorbed chains in terms of trains, loops, and tails is discussed.
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Affiliation(s)
- A Milchev
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - K Binder
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
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6
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Teng Y, Andersen NT, Chen JZY. Statistical Properties of a Slit-Confined Wormlike Chain of Finite Length. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00759] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yue Teng
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Nigel T. Andersen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Jeff Z. Y. Chen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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7
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Milchev A, Binder K. Cylindrical confinement of solutions containing semiflexible macromolecules: surface-induced nematic order versus phase separation. SOFT MATTER 2021; 17:3443-3454. [PMID: 33646224 DOI: 10.1039/d1sm00172h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Solutions of semiflexible polymers confined in cylindrical pores with repulsive walls are studied by Molecular Dynamics simulations for a wide range of polymer concentrations. Both the case where both lengths are of the same order and the case when the persistence length by far exceeds the contour length are considered, and the enhancement of nematic order along the cylinder axis is characterized. With increasing density the character of the surface effect changes from depletion to the formation of a layered structure. For binary 50 : 50 mixtures of the two types of polymers an interplay between surface enrichment of the stiffer component and the isotropic-nematic transition is found, and a phase separated structure with cylindrical symmetry occurs, with the isotropic phase located around the cylinder axis. For melt densities the mixed nematic phase forms at the wall a layer with a screw-like structure of a tilted smectic phase. The observed behavior is tentatively interpreted in terms of the competition of the chain orientational entropy with entropy of mixing and excluded volume due to the wall.
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Affiliation(s)
- Andrey Milchev
- Institute for Physical Chemistry, Bulgarian Academia of Sciences, 1113, Sofia, Bulgaria.
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8
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Polson JM, Hastie CG. Free energy of a knotted polymer confined to narrow cylindrical and conical channels. Phys Rev E 2020; 102:052502. [PMID: 33327190 DOI: 10.1103/physreve.102.052502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/16/2020] [Indexed: 06/12/2023]
Abstract
Monte Carlo simulations are used to study the conformational behavior of a semiflexible polymer confined to cylindrical and conical channels. The channels are sufficiently narrow that the conditions for the Odijk regime are marginally satisfied. For cylindrical confinement, we examine polymers with a single knot of topology 3_{1}, 4_{1}, or 5_{1}, as well as unknotted polymers that are capable of forming S loops. We measure the variation of the free energy F with the end-to-end polymer extension length X and examine the effect of varying the polymer topology, persistence length P, and cylinder diameter D on the free-energy functions. Similarly, we characterize the behavior of the knot span along the channel. We find that increasing the knot complexity increases the typical size of the knot. In the regime of low X, where the knot/S-loop size is large, the conformational behavior is independent of polymer topology. In addition, the scaling properties of the free energy and knot span are in agreement with predictions from a theoretical model constructed using known properties of interacting polymers in the Odijk regime. We also examine the variation of F with the position of a knot in conical channels for various values of the cone angle α. The free energy decreases as the knot moves in a direction where the cone widens, and it also decreases with increasing α and with increasing knot complexity. The behavior is in agreement with predictions from a theoretical model in which the dominant contribution to the change in F is the change in the size of the hairpins as the knot moves to the wider region of the channel.
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Affiliation(s)
- James M Polson
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island, C1A 4P3, Canada
| | - Cameron G Hastie
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island, C1A 4P3, Canada
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9
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Bhandari AB, Dorfman KD. Limitations of the equivalent neutral polymer assumption for theories describing nanochannel-confined DNA. Phys Rev E 2020; 101:012501. [PMID: 32069627 PMCID: PMC7040977 DOI: 10.1103/physreve.101.012501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Indexed: 11/07/2022]
Abstract
The prevailing theories describing DNA confinement in a nanochannel are predicated on the assumption that wall-DNA electrostatic interactions are sufficiently short-ranged such that the problem can be mapped to an equivalent neutral polymer confined by hard walls with an appropriately reduced effective channel size. To determine when this hypothesis is valid, we leveraged a recently reported experimental data set for the fractional extension of DNA molecules in a 250-nm-wide poly(dimethyl siloxane) (PDMS) nanochannel with buffer ionic strengths between 0.075 and 48 mM. Evaluating these data in the context of the weakly correlated telegraph model of DNA confinement reveals that, at ionic strengths greater than 0.3 mM, the average fractional extension of the DNA molecules agree with theoretical predictions with a mean absolute error of 0.04. In contrast, experiments at ionic strengths below 0.3 mM produce average fractional extensions that are systematically smaller than the theoretical predictions with a larger mean absolute error of 0.15. The deviations between experiment and theory display a correlation coefficient of 0.82 with the decay length for the DNA-wall electrostatics, linking the deviations with a breakdown in approximating the DNA with an equivalent neutral polymer.
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Affiliation(s)
- Aditya Bikram Bhandari
- Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Kevin D. Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
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10
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Chuang HM, Reifenberger JG, Bhandari AB, Dorfman KD. Extension distribution for DNA confined in a nanochannel near the Odijk regime. J Chem Phys 2019; 151:114903. [PMID: 31542006 DOI: 10.1063/1.5121305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
DNA confinement in a nanochannel typically is understood via mapping to the confinement of an equivalent neutral polymer by hard walls. This model has proven to be effective for confinement in relatively large channels where hairpin formation is frequent. An analysis of existing experimental data for Escherichia coli DNA extension in channels smaller than the persistence length, combined with an additional dataset for λ-DNA confined in a 34 nm wide channel, reveals a breakdown in this approach as the channel size approaches the Odijk regime of strong confinement. In particular, the predicted extension distribution obtained from the asymptotic solution to the weakly correlated telegraph model for a confined wormlike chain deviates significantly from the experimental distribution obtained for DNA confinement in the 34 nm channel, and the discrepancy cannot be resolved by treating the alignment fluctuations or the effective channel size as fitting parameters. We posit that the DNA-wall electrostatic interactions, which are sensible throughout a significant fraction of the channel cross section in the Odijk regime, are the source of the disagreement between theory and experiment. Dimensional analysis of the wormlike chain propagator in channel confinement reveals the importance of a dimensionless parameter, reflecting the magnitude of the DNA-wall electrostatic interactions relative to thermal energy, which has not been considered explicitly in the prevailing theories for DNA confinement in a nanochannel.
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Affiliation(s)
- Hui-Min Chuang
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Jeffrey G Reifenberger
- Bionano Genomics, Inc., 9640 Towne Centre Drive, Suite 100, San Diego, California 92121, USA
| | - Aditya Bikram Bhandari
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Kevin D Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
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11
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Liang Q, Jiang Y, Chen JZY. Orientationally ordered states of a wormlike chain in spherical confinement. Phys Rev E 2019; 100:032502. [PMID: 31640076 DOI: 10.1103/physreve.100.032502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Indexed: 06/10/2023]
Abstract
One of the basic characteristics of a linear dsDNA molecule is its persistence length, typically of order 50 nm. The DNA chain inflicts a large energy penalty if it is bent sharply at that length scale. Viruses of bacteria, known as bacteriophages, typically have a dimension of a few tens of nanometers. Yet, it is known that a bacteriophage actively packages viral DNA inside the capsid and ejects it afterwards. Here, adopting a commonly used polymer model known as the wormlike chain, we answer an idealized question: Placing a linear DNA molecule inside a spherical cavity, what ordered states can we derive from known tools in statistical physics? Solving the model in a rigorous field-theory framework, we report a universal phase diagram for four orientationally ordered and disordered states, in terms of two relevant physical parameters.
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Affiliation(s)
- Qin Liang
- Faculty of Mathematics and Computational Science, Xiangtan University, Xiangtan, Hunan 411105, China
- School of Chemistry, Beihang University, Beijing 100191, China
| | - Ying Jiang
- School of Chemistry, Beihang University, Beijing 100191, China
| | - Jeff Z Y Chen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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12
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Lee S, Lee Y, Kim Y, Wang C, Park J, Jung GY, Chen Y, Chang R, Ikeda S, Sugiyama H, Jo K. Nanochannel-Confined TAMRA-Polypyrrole Stained DNA Stretching by Varying the Ionic Strength from Micromolar to Millimolar Concentrations. Polymers (Basel) 2018; 11:E15. [PMID: 30959999 PMCID: PMC6401831 DOI: 10.3390/polym11010015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/17/2018] [Accepted: 12/17/2018] [Indexed: 12/19/2022] Open
Abstract
Large DNA molecules have been utilized as a model system to investigate polymer physics. However, DNA visualization via intercalating dyes has generated equivocal results due to dye-induced structural deformation, particularly unwanted unwinding of the double helix. Thus, the contour length increases and the persistence length changes so unpredictably that there has been a controversy. In this paper, we used TAMRA-polypyrrole to stain single DNA molecules. Since this staining did not change the contour length of B-form DNA, we utilized TAMRA-polypyrrole stained DNA as a tool to measure the persistence length by changing the ionic strength. Then, we investigated DNA stretching in nanochannels by varying the ionic strength from 0.06 mM to 47 mM to evaluate several polymer physics theories proposed by Odijk, de Gennes and recent papers to deal with these regimes.
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Affiliation(s)
- Seonghyun Lee
- Department of Chemistry and Integrated Biotechnology, Sogang University, Seoul 04107, Korea.
| | - Yelin Lee
- Department of Chemistry and Integrated Biotechnology, Sogang University, Seoul 04107, Korea.
| | - Yongkyun Kim
- Department of Chemistry and Integrated Biotechnology, Sogang University, Seoul 04107, Korea.
| | - Cong Wang
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea.
| | - Jungyul Park
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea.
| | - Gun Young Jung
- School of Material Science and Engineering, GIST, Gwangju 61005, Korea.
| | - Yenglong Chen
- Institute of Physics, Academia Sinica and Department of Chemical Engineering, National Tsing-Hua University and Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
| | - Rakwoo Chang
- Department of Chemistry, Kwangwoon University, Seoul 01897, Korea.
| | - Shuji Ikeda
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8501, Japan.
| | - Hiroshi Sugiyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8501, Japan.
| | - Kyubong Jo
- Department of Chemistry and Integrated Biotechnology, Sogang University, Seoul 04107, Korea.
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13
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Polson JM. Free Energy of a Folded Semiflexible Polymer Confined to a Nanochannel of Various Geometries. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- James M. Polson
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island C1A 4P3, Canada
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14
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Chen JZY. Self-Avoiding Wormlike Chain Confined in a Cylindrical Tube: Scaling Behavior. PHYSICAL REVIEW LETTERS 2018; 121:037801. [PMID: 30085819 DOI: 10.1103/physrevlett.121.037801] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/27/2018] [Indexed: 05/27/2023]
Abstract
Within a confining tube section, the multithreads of a strongly confined, backfolding polymer exert the excluded-volume repulsions on each other and produce physical properties that are very different from those of a confined ideal chain. The conformational properties of a such confined wormlike chain are of fundamental interest and are also practically useful in understanding the DNA confinement problems. Here, the excluded-volume effects are added to the standard wormlike-chain model by a self-consistent field theory. The numerical solutions are examined in light of their scaling properties.
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Affiliation(s)
- Jeff Z Y Chen
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3GI, Canada
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15
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Bernier S, Huang A, Reisner W, Bhattacharya A. Evolution of Nested Folding States in Compression of a Strongly Confined Semiflexible Chain. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02748] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Simon Bernier
- Department of Physics, McGill University, 3600 rue university, Montreal, Quebec H3A 2T8, Canada
| | - Aiqun Huang
- Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816, United States
| | - Walter Reisner
- Department of Physics, McGill University, 3600 rue university, Montreal, Quebec H3A 2T8, Canada
| | - Aniket Bhattacharya
- Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816, United States
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16
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Ödman D, Werner E, Dorfman KD, Doering CR, Mehlig B. Distribution of label spacings for genome mapping in nanochannels. BIOMICROFLUIDICS 2018; 12:034115. [PMID: 30018694 PMCID: PMC6019347 DOI: 10.1063/1.5038417] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/06/2018] [Indexed: 05/27/2023]
Abstract
In genome mapping experiments, long DNA molecules are stretched by confining them to very narrow channels, so that the locations of sequence-specific fluorescent labels along the channel axis provide large-scale genomic information. It is difficult, however, to make the channels narrow enough so that the DNA molecule is fully stretched. In practice, its conformations may form hairpins that change the spacings between internal segments of the DNA molecule, and thus the label locations along the channel axis. Here, we describe a theory for the distribution of label spacings that explains the heavy tails observed in distributions of label spacings in genome mapping experiments.
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Affiliation(s)
- D Ödman
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
| | - E Werner
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
| | - K D Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - C R Doering
- Center for the Study of Complex Systems, University of Michigan, Ann Arbor, Michigan 48109-1042, USA
| | - B Mehlig
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
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17
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Werner E, Jain A, Muralidhar A, Frykholm K, St Clere Smithe T, Fritzsche J, Westerlund F, Dorfman KD, Mehlig B. Hairpins in the conformations of a confined polymer. BIOMICROFLUIDICS 2018; 12:024105. [PMID: 29576836 PMCID: PMC5844772 DOI: 10.1063/1.5018787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 02/21/2018] [Indexed: 06/01/2023]
Abstract
If a semiflexible polymer confined to a narrow channel bends around by 180°, the polymer is said to exhibit a hairpin. The equilibrium extension statistics of the confined polymer are well understood when hairpins are vanishingly rare or when they are plentiful. Here, we analyze the extension statistics in the intermediate situation via experiments with DNA coated by the protein RecA, which enhances the stiffness of the DNA molecule by approximately one order of magnitude. We find that the extension distribution is highly non-Gaussian, in good agreement with Monte-Carlo simulations of confined discrete wormlike chains. We develop a simple model that qualitatively explains the form of the extension distribution. The model shows that the tail of the distribution at short extensions is determined by conformations with one hairpin.
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Affiliation(s)
- E Werner
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 96 Göteborg, Sweden
| | - A Jain
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | - A Muralidhar
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | - K Frykholm
- Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden
| | - T St Clere Smithe
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 96 Göteborg, Sweden
| | - J Fritzsche
- Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden
| | - F Westerlund
- Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden
| | - K D Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | - B Mehlig
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 96 Göteborg, Sweden
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18
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Reifenberger JG, Cao H, Dorfman KD. Odijk excluded volume interactions during the unfolding of DNA confined in a nanochannel. Macromolecules 2018; 51:1172-1180. [PMID: 29479117 PMCID: PMC5823525 DOI: 10.1021/acs.macromol.7b02466] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report experimental data on the unfolding of human and E. coli genomic DNA molecules shortly after injection into a 45 nm nanochannel. The unfolding dynamics are deterministic, consistent with previous experiments and modeling in larger channels, and do not depend on the biological origin of the DNA. The measured entropic unfolding force per friction per unit contour length agrees with that predicted by combining the Odijk excluded volume with numerical calculations of the Kirkwood diffusivity of confined DNA. The time scale emerging from our analysis has implications for genome mapping in nanochannels, especially as the technology moves towards longer DNA, by setting a lower bound for the delay time before making a measurement.
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Affiliation(s)
| | - Han Cao
- BioNano Genomics Inc., 9640 Towne Centre Drive, Suite 100, San Diego, CA 92121
| | - Kevin D. Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota – Twin Cities, 421 Washington Ave SE, Minneapolis, Minnesota 55455, USA
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Dorfman KD. The Statistical Segment Length of DNA: Opportunities for Biomechanical Modeling in Polymer Physics and Next-Generation Genomics. J Biomech Eng 2018; 140:2653367. [PMID: 28857114 PMCID: PMC5816256 DOI: 10.1115/1.4037790] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/16/2017] [Indexed: 12/28/2022]
Abstract
The development of bright bisintercalating dyes for deoxyribonucleic acid (DNA) in the 1990s, most notably YOYO-1, revolutionized the field of polymer physics in the ensuing years. These dyes, in conjunction with modern molecular biology techniques, permit the facile observation of polymer dynamics via fluorescence microscopy and thus direct tests of different theories of polymer dynamics. At the same time, they have played a key role in advancing an emerging next-generation method known as genome mapping in nanochannels. The effect of intercalation on the bending energy of DNA as embodied by a change in its statistical segment length (or, alternatively, its persistence length) has been the subject of significant controversy. The precise value of the statistical segment length is critical for the proper interpretation of polymer physics experiments and controls the phenomena underlying the aforementioned genomics technology. In this perspective, we briefly review the model of DNA as a wormlike chain and a trio of methods (light scattering, optical or magnetic tweezers, and atomic force microscopy (AFM)) that have been used to determine the statistical segment length of DNA. We then outline the disagreement in the literature over the role of bisintercalation on the bending energy of DNA, and how a multiscale biomechanical approach could provide an important model for this scientifically and technologically relevant problem.
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Affiliation(s)
- Kevin D. Dorfman
- Department of Chemical Engineering and
Materials Science,
University of Minnesota—Twin Cities,
421 Washington Ave SE,
Minneapolis, MN 55455
e-mail:
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Polson JM, Tremblett AF, McLure ZRN. Free Energy of a Folded Polymer under Cylindrical Confinement. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b02114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- James M. Polson
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island C1A 4P3, Canada
| | - Aidan F. Tremblett
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island C1A 4P3, Canada
| | - Zakary R. N. McLure
- Department of Physics, University of Prince Edward Island, 550 University Ave., Charlottetown, Prince Edward Island C1A 4P3, Canada
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