1
|
Zheng CC, Chen YL, Dong HL, Zhang XH, Tan ZJ. Effect of ethanol on the elasticities of double-stranded RNA and DNA revealed by magnetic tweezers and simulations. J Chem Phys 2024; 161:075101. [PMID: 39145565 DOI: 10.1063/5.0211869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 07/29/2024] [Indexed: 08/16/2024] Open
Abstract
The elasticities of double-stranded (ds) DNA and RNA, which are critical to their biological functions and applications in materials science, can be significantly modulated by solution conditions such as ions and temperature. However, there is still a lack of a comprehensive understanding of the role of solvents in the elasticities of dsRNA and dsDNA in a comparative way. In this work, we explored the effect of ethanol solvent on the elasticities of dsRNA and dsDNA by magnetic tweezers and all-atom molecular dynamics simulations. We found that the bending persistence lengths and contour lengths of dsRNA and dsDNA decrease monotonically with the increase in ethanol concentration. Furthermore, the addition of ethanol weakens the positive twist-stretch coupling of dsRNA, while promotes the negative twist-stretch coupling of dsDNA. Counter-intuitively, the lower dielectric environment of ethanol causes a significant re-distribution of counterions and enhanced ion neutralization, which overwhelms the enhanced repulsion along dsRNA/dsDNA, ultimately leading to the softening in bending for dsRNA and dsDNA. Moreover, for dsRNA, ethanol causes slight ion-clamping across the major groove, which weakens the major groove-mediated twist-stretch coupling, while for dsDNA, ethanol promotes the stretch-radius correlation due to enhanced ion binding and consequently enhances the helical radius-mediated twist-stretch coupling.
Collapse
Affiliation(s)
- Chen-Chen Zheng
- School of Physics and Technology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yun-Long Chen
- School of Physics and Technology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hai-Long Dong
- School of Physics and Technology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- School of Physics and Technology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhi-Jie Tan
- School of Physics and Technology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| |
Collapse
|
2
|
Dong HL, Zhang C, Dai L, Zhang Y, Zhang XH, Tan ZJ. The origin of different bending stiffness between double-stranded RNA and DNA revealed by magnetic tweezers and simulations. Nucleic Acids Res 2024; 52:2519-2529. [PMID: 38321947 PMCID: PMC10954459 DOI: 10.1093/nar/gkae063] [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: 06/14/2023] [Revised: 01/16/2024] [Accepted: 01/19/2024] [Indexed: 02/08/2024] Open
Abstract
The subtle differences in the chemical structures of double-stranded (ds) RNA and DNA lead to significant variations in their biological roles and medical implications, largely due to their distinct biophysical properties, such as bending stiffness. Although it is well known that A-form dsRNA is stiffer than B-form dsDNA under physiological salt conditions, the underlying cause of this difference remains unclear. In this study, we employ high-precision magnetic-tweezer experiments along with molecular dynamics simulations and reveal that the relative bending stiffness between dsRNA and dsDNA is primarily determined by the structure- and salt-concentration-dependent ion distribution around their helical structures. At near-physiological salt conditions, dsRNA shows a sparser ion distribution surrounding its phosphate groups compared to dsDNA, causing its greater stiffness. However, at very high monovalent salt concentrations, phosphate groups in both dsRNA and dsDNA become fully neutralized by excess ions, resulting in a similar intrinsic bending persistence length of approximately 39 nm. This similarity in intrinsic bending stiffness of dsRNA and dsDNA is coupled to the analogous fluctuations in their total groove widths and further coupled to the similar fluctuation of base-pair inclination, despite their distinct A-form and B-form helical structures.
Collapse
Affiliation(s)
- Hai-Long Dong
- School of Physics and Technology, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Chen Zhang
- School of Physics and Technology, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
| | - Yan Zhang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- School of Physics and Technology, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Zhi-Jie Tan
- School of Physics and Technology, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| |
Collapse
|
3
|
Kabtiyal P, Robbins A, Jergens E, Castro CE, Winter JO, Poirier MG, Johnston-Halperin E. Localized Plasmonic Heating for Single-Molecule DNA Rupture Measurements in Optical Tweezers. NANO LETTERS 2024; 24:3097-3103. [PMID: 38417053 DOI: 10.1021/acs.nanolett.3c04848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
To date, studies on the thermodynamic and kinetic processes that underlie biological function and nanomachine actuation in biological- and biology-inspired molecular constructs have primarily focused on photothermal heating of ensemble systems, highlighting the need for probes that are localized within the molecular construct and capable of resolving single-molecule response. Here we present an experimental demonstration of wavelength-selective, localized heating at the single-molecule level using the surface plasmon resonance of a 15 nm gold nanoparticle (AuNP). Our approach is compatible with force-spectroscopy measurements and can be applied to studies of the single-molecule thermodynamic properties of DNA origami nanomachines as well as biomolecular complexes. We further demonstrate wavelength selectivity and establish the temperature dependence of the reaction coordinate for base-pair disruption in the shear-rupture geometry, demonstrating the utility and flexibility of this approach for both fundamental studies of local (nanometer-scale) temperature gradients and rapid and multiplexed nanomachine actuation.
Collapse
Affiliation(s)
- Prerna Kabtiyal
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Ariel Robbins
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Elizabeth Jergens
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Carlos E Castro
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jessica O Winter
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Michael G Poirier
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | | |
Collapse
|
4
|
Croquette V, Orero JV, Rieu M, Allemand JF. Magnetic tweezers principles and promises. Methods Enzymol 2024; 694:1-49. [PMID: 38492947 DOI: 10.1016/bs.mie.2024.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024]
Abstract
Magnetic tweezers have become popular with the outbreak of single molecule micromanipulation: catching a single molecule of DNA, RNA or a single protein and applying mechanical constrains using micron-size magnetic beads and magnets turn out to be easy. Various factors have made this possible: the fact that manufacturers have been preparing these beads to catch various biological entities-the ease of use provided by magnets which apply a force or a torque at a distance thus inside a flow cell-some chance: since the forces so generated are in the right range to stretch a single molecule. This is a little less true for torque. Finally, one feature which also appears very important is the simplicity of their calibration using Brownian motion. Here we start by describing magnetic tweezers used routinely in our laboratory where we have tried to develop a device as simple as possible so that the experimentalist can really focus on the biological aspect of the biomolecules that he/she is interested in. We discuss the implications of the various components and their important features. Next, we summarize what is easy to achieve and what is less easy. Then we refer to contributions by other groups who have brought valuable insights to improve magnetic tweezers.
Collapse
Affiliation(s)
- Vincent Croquette
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France; ESPCI Paris, Université PSL, Paris, France.
| | - Jessica Valle Orero
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France; The American University of Paris, Paris, France
| | - Martin Rieu
- Department of Physics, New Biochemistry Building, University of Oxford, South Parks Road, Oxford, United Kingdom
| | - Jean-François Allemand
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| |
Collapse
|
5
|
Ma R, Rashid SA, Velusamy A, Deal BR, Chen W, Petrich B, Li R, Salaita K. Molecular mechanocytometry using tension-activated cell tagging. Nat Methods 2023; 20:1666-1671. [PMID: 37798479 PMCID: PMC11325290 DOI: 10.1038/s41592-023-02030-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/22/2023] [Indexed: 10/07/2023]
Abstract
Flow cytometry is used routinely to measure single-cell gene expression by staining cells with fluorescent antibodies and nucleic acids. Here, we present tension-activated cell tagging (TaCT) to label cells fluorescently based on the magnitude of molecular force transmitted through cell adhesion receptors. As a proof-of-concept, we analyzed fibroblasts and mouse platelets after TaCT using conventional flow cytometry.
Collapse
Affiliation(s)
- Rong Ma
- Department of Chemistry, Emory University, Atlanta, GA, USA
| | | | | | - Brendan R Deal
- Department of Chemistry, Emory University, Atlanta, GA, USA
| | - Wenchun Chen
- Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Brian Petrich
- Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Renhao Li
- Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA, USA.
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA.
| |
Collapse
|
6
|
Liang T, Yang C, Song X, Feng Y, Liu Y, Chen H. Quantification of macromolecule crowding at single-molecule level. Phys Rev E 2023; 108:014406. [PMID: 37583195 DOI: 10.1103/physreve.108.014406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/19/2023] [Indexed: 08/17/2023]
Abstract
Macromolecule crowding has a prominent impact on a series of biochemical processes in the cell. It is also expected to promote macromolecular complexation induced by excluded volume effects, which conflicts with recent advances in the thermodynamic interaction between inert, synthetic polymers, and nucleic acids. Along this line, a method combining high-resolution magnetic tweezers and extended crowder-oxDNA model was applied to resolve these discrepancies by systematically studying the kinetics and thermodynamics of the folding-unfolding transition for an individual DNA hairpin in a crowded environment. More specifically, from the magnetic tweezers-based experiments, the linear dependence of the critical force of the DNA hairpin on the polyethylene glycol (PEG) concentration was demonstrated, which is consistent with the results based on the crowder-oxDNA model in which the Lennard-Jones potential was adopted to express the interaction between the crowders and the DNA hairpin. These consistencies highlight that the excluded volume effects are mainly responsible for the interaction between PEG and the DNA hairpin, which is different from the interaction between dextran and the DNA hairpin. In the meantime, the dependence of the folding rate on the molecule weight of PEG, which was different from fluorescence resonance energy transfer-based results, was identified. The proposed method opens a path to detect the interaction between an inert, synthetic molecule, and the DNA hairpin, which is important to accurately mimic the cytosolic environments using mixtures of different inert molecules.
Collapse
Affiliation(s)
- Ting Liang
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Chao Yang
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Xiaoya Song
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Yuyu Feng
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Yanhui Liu
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Hu Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
| |
Collapse
|
7
|
Zhang J, Zhou EC, He Y, Chai ZL, Ji BZ, Tu Y, Wang HL, Wu WQ, Liu Y, Zhang XH, Liu Y. ZYG11B potentiates the antiviral innate immune response by enhancing cGAS-DNA binding and condensation. Cell Rep 2023; 42:112278. [PMID: 36933219 DOI: 10.1016/j.celrep.2023.112278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 01/17/2023] [Accepted: 03/03/2023] [Indexed: 03/19/2023] Open
Abstract
As a key dsDNA recognition receptor, cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS) plays a vital role in innate immune responses. Activated cGAS, by sensing DNA, catalyzes the synthesis of the secondary messenger cyclic GMP-AMP (cGAMP), which subsequently activates downstream signaling to induce production of interferons and inflammatory cytokines. Here, we report Zyg-11 family member B (ZYG11B) as a potent amplifier in cGAS-mediated immune responses. Knockdown of ZYG11B impairs production of cGAMP and subsequent transcription of interferon and inflammatory cytokines. Mechanistically, ZYG11B enhances cGAS-DNA binding affinity, potentiates cGAS-DNA condensation, and stabilizes the cGAS-DNA condensed complex. Moreover, herpes simplex virus 1 (HSV-1) infection induces ZYG11B degradation in a cGAS-unrelated manner. Our findings not only reveal an important role of ZYG11B in the early stage of DNA-induced cGAS activation but also indicate a viral strategy to dampen the innate immune response.
Collapse
Affiliation(s)
- Jie Zhang
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Er-Chi Zhou
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yan He
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Ze-Lin Chai
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Ben-Zhe Ji
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yi Tu
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Han-Ling Wang
- Xi'an Jiaotong-Livepool University, Suzhou 215123, China
| | - Wen-Qiang Wu
- College of Life Science, Henan University, Kaifeng 475001, China
| | - Yong Liu
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yu Liu
- State Key Laboratory of Virology, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan 430072, China; College of Life Sciences, Wuhan University, Wuhan 430072, China.
| |
Collapse
|
8
|
Suwa M, Tsukahara S, Watarai H. Applications of magnetic and electromagnetic forces in micro-analytical systems. LAB ON A CHIP 2023; 23:1097-1127. [PMID: 36636900 DOI: 10.1039/d2lc00702a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Novel applications of magnetic fields in analytical chemistry have become a remarkable trend in the last two decades. Various magnetic forces have been employed for the migration, orientation, manipulation, and trapping of microparticles, and new analytical platforms for separating and detecting molecules have been proposed. Magnetic materials such as functional magnetic nanoparticles, magnetic nanocomposites, and specially designed magnetic solids and liquids have also been developed for analytical purposes. Numerous attractive applications of magnetic and electromagnetic forces on magnetic and non-magnetic materials have been studied, but fundamental studies to understand the working principles of magnetic forces have been challenging. These studies will form a new field of magneto-analytical science, which should be developed as an interdisciplinary field. In this review, essential pioneering works and recent attractive developments are presented.
Collapse
Affiliation(s)
- M Suwa
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| | - S Tsukahara
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| | - H Watarai
- R3 Institute for Newly-Emerging Science Design, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| |
Collapse
|
9
|
Zhao XC, Dong HL, Li XL, Yang HY, Chen XF, Dai L, Wu WQ, Tan ZJ, Zhang XH. 5-Methyl-cytosine stabilizes DNA but hinders DNA hybridization revealed by magnetic tweezers and simulations. Nucleic Acids Res 2022; 50:12344-12354. [PMID: 36477372 PMCID: PMC9757033 DOI: 10.1093/nar/gkac1122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/31/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022] Open
Abstract
5-Methyl-cytosine (5mC) is one of the most important DNA modifications and plays versatile biological roles. It is well known that 5mC stabilizes DNA duplexes. However, it remains unclear how 5mC affects the kinetics of DNA melting and hybridization. Here, we studied the kinetics of unzipping and rezipping using a 502-bp DNA hairpin by single-molecule magnetic tweezers. Under constant loading rates, 5mC increases the unzipping force but counterintuitively decreases the rezipping force at various salt and temperature conditions. Under constant forces, the non-methylated DNA hops between metastable states during unzipping and rezipping, which implies low energy barriers. Surprisingly, the 5mC DNA can't rezip after fully unzipping unless much lower forces are applied, where it rezips stochastically in a one-step manner, which implies 5mC kinetically hinders DNA hybridization and high energy barriers in DNA hybridization. All-atom molecular dynamics simulations reveal that the 5mC kinetically hinders DNA hybridization due to steric effects rather than electrostatic effects caused by the additional methyl groups of cytosines. Considering the possible high speed of DNA unzipping and zipping during replication and transcription, our findings provide new insights into the biological roles of 5mC.
Collapse
Affiliation(s)
| | | | - Xiao-Lu Li
- The Institute for Advanced Studies, College of Life Sciences, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Hong-Yu Yang
- The Institute for Advanced Studies, College of Life Sciences, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Xue-Feng Chen
- The Institute for Advanced Studies, College of Life Sciences, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
| | - Wen-Qiang Wu
- School of Life Sciences, State Key Laboratory of Crop Stress Adaptation and Improvement, Key Laboratory of Plant Stress Biology, Henan University, Kaifeng 475001, China
| | - Zhi-Jie Tan
- Correspondence may also be addressed to Zhi-Jie Tan. Tel: +86 15827627809; Fax: +86 02768752569;
| | - Xing-Hua Zhang
- To whom correspondence should be addressed. Tel: +86 15827632615; Fax: +86 02768753780;
| |
Collapse
|
10
|
Rico-Pasto M, Ritort F. Temperature-dependent elastic properties of DNA. BIOPHYSICAL REPORTS 2022; 2:100067. [PMID: 36425333 PMCID: PMC9680767 DOI: 10.1016/j.bpr.2022.100067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 07/20/2022] [Indexed: 06/02/2023]
Abstract
Knowledge of the elastic properties, e.g., the persistence length or interphosphate distance, of single-stranded (ss) and double-stranded (ds) DNA under different experimental conditions is critical to characterizing molecular reactions studied with single-molecule techniques. While previous experiments have addressed the dependence of the elastic parameters upon varying ionic strength and contour length, temperature-dependent effects are less studied. Here, we examine the temperature-dependent elasticity of ssDNA and dsDNA in the range 5°C-50°C using a temperature-jump optical trap. We find a temperature softening for dsDNA and a temperature stiffening for ssDNA. Our results highlight the need for a general theory explaining the phenomenology observed.
Collapse
Affiliation(s)
- Marc Rico-Pasto
- Small Biosystems Lab, Condensed Matter Physics Department, University of Barcelona, Barcelona, Spain
| | - Felix Ritort
- Small Biosystems Lab, Condensed Matter Physics Department, University of Barcelona, Barcelona, Spain
- Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
11
|
Meyer AC, Karbach M, Lu P, Müller G. Mechanical response to tension and torque of molecular chains via statistically interacting particles associated with extension, contraction, twist, and supercoiling. Phys Rev E 2022; 105:064502. [PMID: 35854540 DOI: 10.1103/physreve.105.064502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
A methodology for the statistical mechanical analysis of polymeric chains under tension introduced previously is extended to include torque. The response of individual bonds between monomers or of entire groups of monomers to a combination of tension and torque involves, in the framework of this method of analysis, the (thermal or mechanical) activation of a specific mix of statistically interacting particles carrying quanta of extension or contraction and quanta of twist or supercoiling. The methodology, which is elucidated in applications of increasing complexity, is capable of describing the conversion between twist chirality and plectonemic chirality in quasistatic processes. The control variables are force or extension and torque or linkage (a combination of twist and writhe). The versatility of this approach is demonstrated in two applications relevant and promising for double-stranded DNA under controlled tension and torque. One application describes conformational transformations between (native) B-DNA, (underwound) S-DNA, and (overwound) P-DNA in accord with experimental data. The other application describes how the conversion between a twisted chain and a supercoiled chain accommodates variations of linkage and excess length in a buckling transition.
Collapse
Affiliation(s)
- Aaron C Meyer
- Department of Physics, University of Rhode Island, Kingston Rhode Island 02881, USA
| | - Michael Karbach
- Fachgruppe Physik, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Ping Lu
- Department of Physics, Stetson University, DeLand, Florida 32723, USA
| | - Gerhard Müller
- Department of Physics, University of Rhode Island, Kingston Rhode Island 02881, USA
| |
Collapse
|
12
|
Bleha T, Cifra P. Energy/entropy partition of force at DNA stretching. Biopolymers 2022; 113:e23487. [PMID: 35212392 DOI: 10.1002/bip.23487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 02/03/2022] [Accepted: 02/16/2022] [Indexed: 11/09/2022]
Abstract
We compute by molecular simulation the energy/entropic partition of the force in a stretched double-stranded (ds)DNA molecule that is not yet available from the single-molecule measurements. Simulation using the coarse-grained wormlike chain (WLC) model predicts a gradual decrease in the internal (bending) energy of DNA at stretching. The ensuing negative energy contribution to force fU is outweighed by the positive entropy contribution fS . The ratio fU /f, used to assess the polymer elasticity, is about -1 at the moderate extension of DNA. At the high extension, the extra energy expenses due to the contour length elongation make the ratio fU /f less negative. The simulation findings of the hybrid energy/entropy nature of DNA elasticity at weak and moderate forces are supported by computations using the thermoelastic method mimicking the polymer experiments in bulk. It is contended that the observation of the negative energy elasticity in DNA can be generalized to other semiflexible polymers described by the WLC model.
Collapse
Affiliation(s)
- Tomas Bleha
- Polymer Institute, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Peter Cifra
- Polymer Institute, Slovak Academy of Sciences, Bratislava, Slovakia
| |
Collapse
|
13
|
Magnetic tweezers: development and use in single-molecule research. Biotechniques 2022; 72:65-72. [PMID: 35037472 DOI: 10.2144/btn-2021-0104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The use of magnetic tweezers for single-molecule micromanipulation has evolved rapidly since its introduction approximately 30 years ago. Magnetic tweezers have provided important insights into the dynamic activity of DNA-processing enzymes, as well as detailed, high-resolution information on the mechanical properties of DNA. These successes have been enabled by major advancements in the hardware and software components of these devices. These developments now allow for a much richer mechanistic understanding of the functions and mechanisms of DNA-binding enzymes. In this review, the authors briefly discuss the fundamental principles of magnetic tweezers and describe the advancements that have made it a superlative tool for investigating, at the single-molecule level, DNA and its interactions with DNA-binding proteins.
Collapse
|
14
|
Moon HM, Park JS, Lee IB, Kang YI, Jung HJ, An D, Shin Y, Kim MJ, Kim HI, Song JJ, Kim J, Lee NK, Hong SC. Cisplatin fastens chromatin irreversibly even at a high chloride concentration. Nucleic Acids Res 2021; 49:12035-12047. [PMID: 34865121 PMCID: PMC8643659 DOI: 10.1093/nar/gkab922] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 09/12/2021] [Accepted: 09/28/2021] [Indexed: 12/17/2022] Open
Abstract
Cisplatin is one of the most potent anti-cancer drugs developed so far. Recent studies highlighted several intriguing roles of histones in cisplatin's anti-cancer effect. Thus, the effect of nucleosome formation should be considered to give a better account of the anti-cancer effect of cisplatin. Here we investigated this important issue via single-molecule measurements. Surprisingly, the reduced activity of cisplatin under [NaCl] = 180 mM, corresponding to the total concentration of cellular ionic species, is still sufficient to impair the integrity of a nucleosome by retaining its condensed structure firmly, even against severe mechanical and chemical disturbances. Our finding suggests that such cisplatin-induced fastening of chromatin can inhibit nucleosome remodelling required for normal biological functions. The in vitro chromatin transcription assay indeed revealed that the transcription activity was effectively suppressed in the presence of cisplatin. Our direct physical measurements on cisplatin-nucleosome adducts suggest that the formation of such adducts be the key to the anti-cancer effect by cisplatin.
Collapse
Affiliation(s)
- Hyeon-Min Moon
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Korea.,Department of Physics, Korea University, Seoul 02841, Korea
| | - Jin-Sung Park
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Korea
| | - Il-Buem Lee
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Korea.,Department of Physics, Korea University, Seoul 02841, Korea
| | - Young-Im Kang
- Department of Physics, Korea University, Seoul 02841, Korea
| | - Hae Jun Jung
- Department of Physics, Korea University, Seoul 02841, Korea
| | - Dongju An
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Yumi Shin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Min Ji Kim
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hugh I Kim
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Ji-Joon Song
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Nam-Kyung Lee
- Department of Physics, Sejong University, Seoul 05006, Korea
| | - Seok-Cheol Hong
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Korea.,Department of Physics, Korea University, Seoul 02841, Korea
| |
Collapse
|
15
|
Liang J, Li J, Zhong Z, Rujiralai T, Ma J. Quantifying the force in flow-cell based single-molecule stretching experiments. NANOSCALE 2021; 13:15916-15927. [PMID: 34522927 DOI: 10.1039/d1nr04748e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The flow-cell based single-molecule manipulation technique has found many applications in the study of DNA mechanics and protein-DNA interactions. However, the force in these experiments has not been fully characterized and is usually limited to a moderate force regime (<25 pN). In this work, using the "tethered-bead" assay, the hydrodynamic drag of DNA has been quantitatively evaluated based on a "bead-spring chain" model. The force derived from the Brownian motion of the bead thus contains both contributions from this equivalent hydrodynamic drag of DNA and the pulling force from the tethered bead. Next, using flow-cell based DNA pulling experiments, the linear relationship between the flow rate and total hydrodynamic force on the bead-DNA system has been demonstrated to be valid over a wide force range (0-110 pN). Consequently, the force can be directly converted from the flow rate by a linear factor that can be calibrated either by the bead's Brownian motion at low flow rates or using DNA overstretching transition. Furthermore, the hydrodynamic force and torque due to the shear flow on the bead as well as the equivalent stretching force on DNA are calculated based on theoretical models with the hydrodynamic drag on DNA also considered. The calculated force-extension curves show a good agreement with the measured ones. These results offer important insights into the force in flow-cell based single-molecule stretching experiments and provide a foundation for establishing flow-cells as a simple, low-cost, yet flexible and precise tool for single-molecule force measurements over a wide force range.
Collapse
Affiliation(s)
- Jialun Liang
- School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Jiaxi Li
- School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Zhensheng Zhong
- School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Thitima Rujiralai
- Division of Physical Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand
| | - Jie Ma
- School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| |
Collapse
|
16
|
Xu W, Dunlap D, Finzi L. Energetics of twisted DNA topologies. Biophys J 2021; 120:3242-3252. [PMID: 33974883 DOI: 10.1016/j.bpj.2021.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 03/30/2021] [Accepted: 05/05/2021] [Indexed: 11/30/2022] Open
Abstract
Our goal is to review the main theoretical models used to calculate free energy changes associated with common, torsion-induced conformational changes in DNA and provide the resulting equations hoping to facilitate quantitative analysis of both in vitro and in vivo studies. This review begins with a summary of work regarding the energy change of the negative supercoiling-induced B- to L-DNA transition, followed by a discussion of the energetics associated with the transition to Z-form DNA. Finally, it describes the energy changes associated with the formation of DNA curls and plectonemes, which can regulate DNA-protein interactions and promote cross talk between distant DNA elements, respectively. The salient formulas and parameters for each scenario are summarized in table format to facilitate comparison and provide a concise, user-friendly resource.
Collapse
Affiliation(s)
- Wenxuan Xu
- Emory University, Department of Physics, Atlanta, Georgia
| | - David Dunlap
- Emory University, Department of Physics, Atlanta, Georgia
| | - Laura Finzi
- Emory University, Department of Physics, Atlanta, Georgia.
| |
Collapse
|
17
|
Bustamante CJ, Chemla YR, Liu S, Wang MD. Optical tweezers in single-molecule biophysics. NATURE REVIEWS. METHODS PRIMERS 2021; 1:25. [PMID: 34849486 PMCID: PMC8629167 DOI: 10.1038/s43586-021-00021-6] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/12/2021] [Indexed: 12/15/2022]
Abstract
Optical tweezers have become the method of choice in single-molecule manipulation studies. In this Primer, we first review the physical principles of optical tweezers and the characteristics that make them a powerful tool to investigate single molecules. We then introduce the modifications of the method to extend the measurement of forces and displacements to torques and angles, and to develop optical tweezers with single-molecule fluorescence detection capabilities. We discuss force and torque calibration of these instruments, their various modes of operation and most common experimental geometries. We describe the type of data obtained in each experimental design and their analyses. This description is followed by a survey of applications of these methods to the studies of protein-nucleic acid interactions, protein/RNA folding and molecular motors. We also discuss data reproducibility, the factors that lead to the data variability among different laboratories and the need to develop field standards. We cover the current limitations of the methods and possible ways to optimize instrument operation, data extraction and analysis, before suggesting likely areas of future growth.
Collapse
Affiliation(s)
- Carlos J. Bustamante
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Yann R. Chemla
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Michelle D. Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, NY, USA
| |
Collapse
|
18
|
Zhang X, Zhang Y, Zhang W. Dynamic topology of double-stranded telomeric DNA studied by single-molecule manipulation in vitro. Nucleic Acids Res 2020; 48:6458-6470. [PMID: 32496520 PMCID: PMC7337930 DOI: 10.1093/nar/gkaa479] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/17/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
The dynamic topological structure of telomeric DNA is closely related to its biological function; however, no such structural information on full-length telomeric DNA has been reported due to difficulties synthesizing long double-stranded telomeric DNA. Herein, we developed an EM-PCR and TA cloning-based approach to synthesize long-chain double-stranded tandem repeats of telomeric DNA. Using mechanical manipulation assays based on single-molecule atomic force microscopy, we found that mechanical force can trigger the melting of double-stranded telomeric DNA and the formation of higher-order structures (G-quadruplexes or i-motifs). Our results show that only when both the G-strand and C-strand of double-stranded telomeric DNA form higher-order structures (G-quadruplexes or i-motifs) at the same time (e.g. in the presence of 100 mM KCl under pH 4.7), that the higher-order structure(s) can remain after the external force is removed. The presence of monovalent K+, single-wall carbon nanotubes (SWCNTs), acidic conditions, or short G-rich fragments (∼30 nt) can shift the transition from dsDNA to higher-order structures. Our results provide a new way to regulate the topology of telomeric DNA.
Collapse
Affiliation(s)
- Xiaonong Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Yingqi Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| |
Collapse
|
19
|
Singh J, Purohit PK. Statistical mechanics of a double-stranded rod model for DNA melting and elasticity. SOFT MATTER 2020; 16:7715-7726. [PMID: 32734998 PMCID: PMC7484343 DOI: 10.1039/d0sm00521e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The double-helical topology of DNA molecules observed at room temperature in the absence of any external loads can be disrupted by increasing the bath temperature or by applying tensile forces, leading to spontaneous strand separation known as DNA melting. Here, continuum mechanics of a 2D birod is combined with statistical mechanics to formulate a unified framework for studying both thermal melting and tensile force induced melting of double-stranded molecules: it predicts the variation of melting temperature with tensile load, provides a mechanics-based understanding of the cooperativity observed in melting transitions, and reveals an interplay between solution electrostatics and micromechanical deformations of DNA which manifests itself as an increase in the melting temperature with increasing ion concentration. This novel predictive framework sheds light on the micromechanical aspects of DNA melting and predicts trends that were observed experimentally or extracted phenomenologically using the Clayperon equation.
Collapse
Affiliation(s)
- Jaspreet Singh
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, 19104, USA.
| | - Prashant K Purohit
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, 19104, USA.
| |
Collapse
|
20
|
Yang D, Liu W, Deng X, Xie W, Chen H, Zhong Z, Ma J. GC-Content Dependence of Elastic and Overstretching Properties of DNA:RNA Hybrid Duplexes. Biophys J 2020; 119:852-861. [PMID: 32738216 DOI: 10.1016/j.bpj.2020.06.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/22/2020] [Accepted: 06/18/2020] [Indexed: 01/25/2023] Open
Abstract
DNA:RNA hybrid duplex plays important roles in various biological processes. Both its structural stability and interactions with proteins are highly sequence dependent. In this study, we utilize homebuilt optical tweezers to investigate how GC contents in the sequence influence the structural and mechanical properties of DNA:RNA hybrid by measuring its contour length, elasticities, and overstretching dynamics. Our results support that the DNA:RNA hybrid adopts a conformation between the A- and B-form helix, and the GC content does not affect its structural and elastic parameters obviously when varying from 40 to 60% before the overstretching transition of DNA:RNA hybrid occurs. In the overstretching transition, however, our study unravels significant heterogeneity and strong sequence dependence, suggesting the presence of a highly dynamic competition between the two processes, namely the S-form duplex formation (nonhysteretic) and the unpeeling (hysteretic). Analyzing the components left in DNA:RNA hybrid after the overstretching transition suggests that the RNA strand is more easily unpeeled than the DNA strand, whereas an increase in the GC content from 40 to 60% can significantly reduce unpeeling. Large hysteresis is observed between the stretching and relaxation processes, which is also quantitatively correlated with the percentage of unpeeling in the DNA:RNA duplex. Increasing in both the salt concentration and GC content can effectively reduce the hysteresis with the latter being more significant. Together, our study reveals that the mechanical properties of DNA:RNA hybrid duplexes are significantly different from double-stranded DNA and double-stranded RNA, and its overstretching behavior is highly sequence dependent. These results should be taken into account in the future studies on DNA:RNA-hybrid-related functional structures and motor proteins.
Collapse
Affiliation(s)
- Dongni Yang
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wenzhao Liu
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiangyu Deng
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Xie
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Hu Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, Fujian, China
| | - Zhensheng Zhong
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China.
| | - Jie Ma
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, China; State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong, China.
| |
Collapse
|
21
|
Yang YJ, Dong HL, Qiang XW, Fu H, Zhou EC, Zhang C, Yin L, Chen XF, Jia FC, Dai L, Tan ZJ, Zhang XH. Cytosine Methylation Enhances DNA Condensation Revealed by Equilibrium Measurements Using Magnetic Tweezers. J Am Chem Soc 2020; 142:9203-9209. [DOI: 10.1021/jacs.9b11957] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Ya-Jun Yang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Hai-Long Dong
- Department of Physics and Key Laboratory of Artificial Micro & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Xiao-Wei Qiang
- Department of Physics and Key Laboratory of Artificial Micro & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hang Fu
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Er-Chi Zhou
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Chen Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Lei Yin
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Xue-Feng Chen
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Fu-Chao Jia
- Laboratory of Functional Molecules and Materials, School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
| | - Zhi-Jie Tan
- Department of Physics and Key Laboratory of Artificial Micro & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| |
Collapse
|
22
|
Fu H, Zhang C, Qiang XW, Yang YJ, Dai L, Tan ZJ, Zhang XH. Opposite Effects of High-Valent Cations on the Elasticities of DNA and RNA Duplexes Revealed by Magnetic Tweezers. PHYSICAL REVIEW LETTERS 2020; 124:058101. [PMID: 32083903 DOI: 10.1103/physrevlett.124.058101] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
We report that trivalent cobalt hexammine cations decrease the persistence length, stretching modulus, helical density, and size of plectonemes formed under torque of DNA but increase those of RNA. Divalent magnesium cations, however, decrease the persistence lengths, contour lengths, and sizes of plectonemes while increasing the helical densities of both DNA and RNA. The experimental results are explained by different binding modes of the cations on DNA and RNA in our all-atom molecular dynamics simulations. The significant variations of the helical densities and structures of DNA and RNA duplexes induced by high-valent cations may affect interactions of the duplexes with proteins.
Collapse
Affiliation(s)
- Hang Fu
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Chen Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Xiao-Wei Qiang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Ya-Jun Yang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| |
Collapse
|
23
|
Meyer AC, Öz Y, Gundlach N, Karbach M, Lu P, Müller G. Molecular chains under tension: Thermal and mechanical activation of statistically interacting extension and contraction particles. Phys Rev E 2020; 101:022504. [PMID: 32168618 DOI: 10.1103/physreve.101.022504] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/23/2020] [Indexed: 11/07/2022]
Abstract
This work introduces a methodology for the statistical mechanical analysis of polymeric chains under tension controlled by optical or magnetic tweezers at thermal equilibrium with an embedding fluid medium. The response of single bonds between monomers or of entire groups of monomers to tension is governed by the activation of statistically interacting particles representing quanta of extension or contraction. This method of analysis is capable of describing thermal unbending of the freely jointed or wormlike chain kind, linear or nonlinear contour elasticity, and structural transformations including effects of cooperativity. The versatility of this approach is demonstrated in an application to double-stranded DNA undergoing torsionally unconstrained stretching across three regimes of mechanical response including an overstretching transition. The three-regime force-extension characteristic, derived from a single free-energy expression, accurately matches empirical evidence.
Collapse
Affiliation(s)
- Aaron C Meyer
- Department of Physics, University of Rhode Island, Kingston, Rhode Island 02881, USA
| | - Yahya Öz
- Fachgruppe Physik, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Norman Gundlach
- Fachgruppe Physik, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Michael Karbach
- Fachgruppe Physik, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Ping Lu
- Department of Applied Science and Mathematics, Bluefield State College, Bluefield, West Virginia 24701, USA
| | - Gerhard Müller
- Department of Physics, University of Rhode Island, Kingston, Rhode Island 02881, USA
| |
Collapse
|
24
|
Zhao X, Guo S, Lu C, Chen J, Le S, Fu H, Yan J. Single-molecule manipulation quantification of site-specific DNA binding. Curr Opin Chem Biol 2019; 53:106-117. [DOI: 10.1016/j.cbpa.2019.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/24/2019] [Accepted: 08/24/2019] [Indexed: 10/25/2022]
|
25
|
Molecular scaffolds: when DNA becomes the hardware for single-molecule investigations. Curr Opin Chem Biol 2019; 53:192-203. [DOI: 10.1016/j.cbpa.2019.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 09/21/2019] [Accepted: 09/24/2019] [Indexed: 01/14/2023]
|
26
|
Statistical physics and mesoscopic modeling to interpret tethered particle motion experiments. Methods 2019; 169:57-68. [PMID: 31302177 DOI: 10.1016/j.ymeth.2019.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/11/2019] [Accepted: 07/07/2019] [Indexed: 11/22/2022] Open
Abstract
Tethered particle motion experiments are versatile single-molecule techniques enabling one to address in vitro the molecular properties of DNA and its interactions with various partners involved in genetic regulations. These techniques provide raw data such as the tracked particle amplitude of movement, from which relevant information about DNA conformations or states must be recovered. Solving this inverse problem appeals to specific theoretical tools that have been designed in the two last decades, together with the data pre-processing procedures that ought to be implemented to avoid biases inherent to these experimental techniques. These statistical tools and models are reviewed in this paper.
Collapse
|
27
|
Yang YJ, Song L, Zhao XC, Zhang C, Wu WQ, You HJ, Fu H, Zhou EC, Zhang XH. A Universal Assay for Making DNA, RNA, and RNA-DNA Hybrid Configurations for Single-Molecule Manipulation in Two or Three Steps without Ligation. ACS Synth Biol 2019; 8:1663-1672. [PMID: 31264849 DOI: 10.1021/acssynbio.9b00241] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Despite having a great variety of topologies, most DNA, RNA, and RNA-DNA hybrid (RDH) configurations for single-molecule manipulation are composed of several single-stranded (ss) DNA and ssRNA strands, with functional labels at the two ends for surface tethering. On this basis, we developed a simple, robust, and universal amplification-annealing (AA) assay for making all these configurations in two or three steps without inefficient digestion and ligation reactions. As examples, we made ssDNA, short ssDNA with double-stranded (ds) DNA handles, dsDNA with ssDNA handles, replication-fork shaped DNA/RDH/RNA, DNA holiday junction, three-site multiple-labeled and nicked DNA, torsion-constrained RNA/RDH, and short ssRNA with RDH handles. In addition to single-molecule manipulation techniques including optical tweezers, magnetic tweezers, and atomic force microscopy, these configurations can be applied in other surface-tethering techniques as well.
Collapse
Affiliation(s)
- Ya-Jun Yang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Lun Song
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Xiao-Cong Zhao
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Chen Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Wen-Qiang Wu
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng 475001, China
| | - Hui-Juan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Hang Fu
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Er-Chi Zhou
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| | - Xing-Hua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan 430072, China
| |
Collapse
|
28
|
Liu JH, Xi K, Zhang X, Bao L, Zhang X, Tan ZJ. Structural Flexibility of DNA-RNA Hybrid Duplex: Stretching and Twist-Stretch Coupling. Biophys J 2019; 117:74-86. [PMID: 31164196 PMCID: PMC6626833 DOI: 10.1016/j.bpj.2019.05.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/25/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022] Open
Abstract
DNA-RNA hybrid (DRH) duplexes play essential roles during the replication of DNA and the reverse transcription of RNA viruses, and their flexibility is important for their biological functions. Recent experiments indicated that A-form RNA and B-form DNA have a strikingly different flexibility in stretching and twist-stretch coupling, and the structural flexibility of DRH duplex is of great interest, especially in stretching and twist-stretch coupling. In this work, we performed microsecond all-atom molecular dynamics simulations with new AMBER force fields to characterize the structural flexibility of DRH duplex in stretching and twist-stretch coupling. We have calculated all the helical parameters, stretch modulus, and twist-stretch coupling parameters for the DRH duplex. First, our analyses on structure suggest that the DRH duplex exhibits an intermediate conformation between A- and B-forms and closer to A-form, which can be attributed to the stronger rigidity of the RNA strand than the DNA strand. Second, our calculations show that the DRH duplex has the stretch modulus of 834 ± 34 pN and a very weak twist-stretch coupling. Our quantitative analyses indicate that, compared with DNA and RNA duplexes, the different flexibility of the DRH duplex in stretching and twist-stretch coupling is mainly attributed to its apparently different basepair inclination in the helical structure.
Collapse
Affiliation(s)
- Ju-Hui Liu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Kun Xi
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xi Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Lei Bao
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xinghua Zhang
- College of Life Science, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
| |
Collapse
|
29
|
Zhao XC, Fu H, Song L, Yang YJ, Zhou EC, Liu GX, Chen XF, Li Z, Wu WQ, Zhang XH. S-DNA and RecA/RAD51-Mediated Strand Exchange in Vitro. Biochemistry 2019; 58:2009-2016. [PMID: 30900876 DOI: 10.1021/acs.biochem.8b01125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
S-DNA (stretched DNA) is an elongated base-paired DNA conformation under high tension. Because the RecA/Rad51 family DNA recombinases form helical filaments on DNA and mediate the formation of the DNA triplex (D-loop), in which the DNA is stretched, and because the extension of these nucleoprotein filaments is similar to the extension of S-DNA, S-DNA has long been hypothesized as a possible state of DNA that participants in RecA/Rad51-mediated DNA strand exchange in homologous recombination. Such a hypothesis, however, is still lacking direct experimental studies. In this work, we have studied the polymerization and strand exchange on S-DNA mediated by Escherichia coli RecA, human Rad51, and Saccharomyces cerevisiae Rad51 by single-molecule magnetic tweezers. We report that RecA/Rad51 polymerizes faster on S-DNA than on B-DNA with the same buffer conditions. Furthermore, the RecA/Rad51-mediated DNA triplex forms faster from S-DNA than from B-DNA together with the homologous single-stranded DNA. These results provide evidence that S-DNA can interact with RecA and Rad51 and shed light on the possible functions of S-DNA.
Collapse
Affiliation(s)
- Xiao-Cong Zhao
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Hang Fu
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Lun Song
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Ya-Jun Yang
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Er-Chi Zhou
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Guang-Xue Liu
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Xue-Feng Chen
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Zhuo Li
- Third Institute of Oceanography , State Oceanic Administration , Xiamen 361005 , China
| | - Wen-Qiang Wu
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology , Henan University , Kaifeng 475001 , China
| | - Xing-Hua Zhang
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| |
Collapse
|
30
|
Cristofalo M, Kovari D, Corti R, Salerno D, Cassina V, Dunlap D, Mantegazza F. Nanomechanics of Diaminopurine-Substituted DNA. Biophys J 2019; 116:760-771. [PMID: 30795872 DOI: 10.1016/j.bpj.2019.01.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 10/27/2022] Open
Abstract
2,6-diaminopurine (DAP) is a nucleobase analog of adenine. When incorporated into double-stranded DNA (dsDNA), it forms three hydrogen bonds with thymine. Rare in nature, DAP substitution alters the physical characteristics of a DNA molecule without sacrificing sequence specificity. Here, we show that in addition to stabilizing double-strand hybridization, DAP substitution also changes the mechanical and conformational properties of dsDNA. Thermal melting experiments reveal that DAP substitution raises melting temperatures without diminishing sequence-dependent effects. Using a combination of atomic force microscopy (AFM), magnetic tweezer (MT) nanomechanical assays, and circular dichroism spectroscopy, we demonstrate that DAP substitution increases the flexural rigidity of dsDNA yet also facilitates conformational shifts, which manifest as changes in molecule length. DAP substitution increases both the static and dynamic persistence length of DNA (measured by AFM and MT, respectively). In the static case (AFM), in which tension is not applied to the molecule, the contour length of DAP-DNA appears shorter than wild-type (WT)-DNA; under tension (MT), they have similar dynamic contour lengths. At tensions above 60 pN, WT-DNA undergoes characteristic overstretching because of strand separation (tension-induced melting) and spontaneous adoption of a conformation termed S-DNA. Cyclic overstretching and relaxation of WT-DNA at near-zero loading rates typically yields hysteresis, indicative of tension-induced melting; conversely, cyclic stretching of DAP-DNA showed little or no hysteresis, consistent with the adoption of the S-form, similar to what has been reported for GC-rich sequences. However, DAP-DNA overstretching is distinct from GC-rich overstretching in that it happens at a significantly lower tension. In physiological salt conditions, evenly mixed AT/GC DNA typically overstretches around 60 pN. GC-rich sequences overstretch at similar if not slightly higher tensions. Here, we show that DAP-DNA overstretches at 52 pN. In summary, DAP substitution decreases the overall stability of the B-form double helix, biasing toward non-B-form DNA helix conformations at zero tension and facilitating the B-to-S transition at high tension.
Collapse
Affiliation(s)
- Matteo Cristofalo
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - Daniel Kovari
- Department of Physics, Emory University, Atlanta, Georgia
| | - Roberta Corti
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - Domenico Salerno
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy.
| | - Valeria Cassina
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - David Dunlap
- Department of Physics, Emory University, Atlanta, Georgia.
| | | |
Collapse
|
31
|
Zhang C, Fu H, Yang Y, Zhou E, Tan Z, You H, Zhang X. The Mechanical Properties of RNA-DNA Hybrid Duplex Stretched by Magnetic Tweezers. Biophys J 2018; 116:196-204. [PMID: 30635125 DOI: 10.1016/j.bpj.2018.12.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 12/25/2022] Open
Abstract
RNA can anneal to its DNA template to generate an RNA-DNA hybrid (RDH) duplex and a displaced DNA strand, termed R-loop. RDH duplex occupies up to 5% of the mammalian genome and plays important roles in many biological processes. The functions of RDH duplex are affected by its mechanical properties, including the elasticity and the conformation transitions. The mechanical properties of RDH duplex, however, are still unclear. In this work, we studied the mechanical properties of RDH duplex using magnetic tweezers in comparison with those of DNA and RNA duplexes with the same sequences. We report that the contour length of RDH duplex is ∼0.30 nm/bp, and the stretching modulus of RDH duplex is ∼660 pN, neither of which is sensitive to NaCl concentration. The persistence length of RDH duplex depends on NaCl concentration, decreasing from ∼63 nm at 1 mM NaCl to ∼49 nm at 500 mM NaCl. Under high tension of ∼60 pN, the end-opened RDH duplex undergoes two distinct overstretching transitions; at high salt in which the basepairs are stable, it undergoes the nonhysteretic transition, leading to a basepaired elongated structure, whereas at low salt, it undergoes a hysteretic peeling transition, leading to the single-stranded DNA strand under force and the single-stranded RNA strand coils. The peeled RDH is difficult to reanneal back to the duplex conformation, which may be due to the secondary structures formed in the coiled single-stranded RNA strand. These results help us understand the full picture of the structures and mechanical properties of nucleic acid duplexes in solution and provide a baseline for studying the interaction of RDH with proteins at the single-molecule level.
Collapse
Affiliation(s)
- Chen Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Hang Fu
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Yajun Yang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Erchi Zhou
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Zhijie Tan
- School of Physics and Technology, Wuhan University, Wuhan, China
| | - Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xinghua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
| |
Collapse
|
32
|
Chakraborty D, Hori N, Thirumalai D. Sequence-Dependent Three Interaction Site Model for Single- and Double-Stranded DNA. J Chem Theory Comput 2018; 14:3763-3779. [PMID: 29870236 PMCID: PMC6423546 DOI: 10.1021/acs.jctc.8b00091] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We develop a robust coarse-grained model for single- and double-stranded DNA by representing each nucleotide by three interaction sites (TIS) located at the centers of mass of sugar, phosphate, and base. The resulting TIS model includes base-stacking, hydrogen bond, and electrostatic interactions as well as bond-stretching and bond angle potentials that account for the polymeric nature of DNA. The choices of force constants for stretching and the bending potentials were guided by a Boltzmann inversion procedure using a large representative set of DNA structures extracted from the Protein Data Bank. Some of the parameters in the stacking interactions were calculated using a learning procedure, which ensured that the experimentally measured melting temperatures of dimers are faithfully reproduced. Without any further adjustments, the calculations based on the TIS model reproduce the experimentally measured salt and sequence-dependence of the size of single-stranded DNA (ssDNA), as well as the persistence lengths of poly(dA) and poly(dT) chains. Interestingly, upon application of mechanical force, the extension of poly(dA) exhibits a plateau, which we trace to the formation of stacked helical domains. In contrast, the force-extension curve (FEC) of poly(dT) is entropic in origin and could be described by a standard polymer model. We also show that the persistence length of double-stranded DNA, formed from two complementary ssDNAs, is consistent with the prediction based on the worm-like chain. The persistence length, which decreases with increasing salt concentration, is in accord with the Odijk-Skolnick-Fixman theory intended for stiff polyelectrolyte chains near the rod limit. Our model predicts the melting temperatures of DNA hairpins with excellent accuracy, and we are able to recover the experimentally known sequence-specific trends. The range of applications, which did not require adjusting any parameter after the initial construction based solely on PDB structures and melting profiles of dimers, attests to the transferability and robustness of the TIS model for ssDNA and dsDNA.
Collapse
Affiliation(s)
- Debayan Chakraborty
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Naoto Hori
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - D. Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| |
Collapse
|
33
|
Zhang X, Bao L, Wu YY, Zhu XL, Tan ZJ. Radial distribution function of semiflexible oligomers with stretching flexibility. J Chem Phys 2018; 147:054901. [PMID: 28789545 DOI: 10.1063/1.4991689] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The radial distribution of the end-to-end distance Ree is crucial for quantifying the global size and flexibility of a linear polymer. For semiflexible polymers, several analytical formulas have been derived for the radial distribution of Ree ignoring the stretching flexibility. However, for semiflexible oligomers, such as DNA or RNA, the stretching flexibility can be rather pronounced and can significantly affect the radial distribution of Ree. In this study, we obtained an extended formula that includes the stretch modulus to describe the distribution of Ree for semiflexible oligomers on the basis of previous formulas for semiflexible polymers without stretching flexibility. The extended formula was validated by extensive Monte Carlo simulations over wide ranges of the stretch modulus and persistence length, as well as all-atom molecular dynamics simulations of short DNAs and RNAs. Additionally, our analyses showed that the effect of stretching flexibility on the distribution of Ree becomes negligible for DNAs longer than ∼130 base pairs and RNAs longer than ∼240 base pairs.
Collapse
Affiliation(s)
- Xi Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Lei Bao
- Center for Theoretical Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yuan-Yan Wu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Xiao-Long Zhu
- Department of Physics, School of Physics and Information Engineering, Jianghan University, Wuhan 430056, China
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China
| |
Collapse
|
34
|
Abstract
Nucleoid-associated proteins (NAPs) are important factors in shaping bacterial nucleoid and regulating global gene expression. A great deal of insights into NAPs can be obtained through studies using single DNA molecule, which has been made possible owing to recent rapid development of single-DNA manipulation techniques. These studies provide information on modes of binding to DNA, which shed light on the mechanism underlying the regulatory function of NAPs. In addition, how NAPs organize DNA and thus their contribution to chromosomal DNA packaging can be determined. In this chapter, we introduce transverse magnetic tweezers that allows for convenient manipulation of long DNA molecules, and its applications in studies of NAPs as exemplified by the E. coli H-NS protein. We describe how transverse magnetic tweezers is a powerful tool that can be used to characterize the DNA binding and organization modes of NAPs and how such information leads to better understanding of its roles in DNA packaging of bacterial nucleoid and transcription regulation.
Collapse
|
35
|
Walder R, Van Patten WJ, Adhikari A, Perkins TT. Going Vertical To Improve the Accuracy of Atomic Force Microscopy Based Single-Molecule Force Spectroscopy. ACS NANO 2018; 12:198-207. [PMID: 29244486 DOI: 10.1021/acsnano.7b05721] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Single-molecule force spectroscopy (SMFS) is a powerful technique to characterize the energy landscape of individual proteins, the mechanical properties of nucleic acids, and the strength of receptor-ligand interactions. Atomic force microscopy (AFM)-based SMFS benefits from ongoing progress in improving the precision and stability of cantilevers and the AFM itself. Underappreciated is that the accuracy of such AFM studies remains hindered by inadvertently stretching molecules at an angle while measuring only the vertical component of the force and extension, degrading both measurements. This inaccuracy is particularly problematic in AFM studies using double-stranded DNA and RNA due to their large persistence length (p ≈ 50 nm), often limiting such studies to other SMFS platforms (e.g., custom-built optical and magnetic tweezers). Here, we developed an automated algorithm that aligns the AFM tip above the DNA's attachment point to a coverslip. Importantly, this algorithm was performed at low force (10-20 pN) and relatively fast (15-25 s), preserving the connection between the tip and the target molecule. Our data revealed large uncorrected lateral offsets for 100 and 650 nm DNA molecules [24 ± 18 nm (mean ± standard deviation) and 180 ± 110 nm, respectively]. Correcting this offset yielded a 3-fold improvement in accuracy and precision when characterizing DNA's overstretching transition. We also demonstrated high throughput by acquiring 88 geometrically corrected force-extension curves of a single individual 100 nm DNA molecule in ∼40 min and versatility by aligning polyprotein- and PEG-based protein-ligand assays. Importantly, our software-based algorithm was implemented on a commercial AFM, so it can be broadly adopted. More generally, this work illustrates how to enhance AFM-based SMFS by developing more sophisticated data-acquisition protocols.
Collapse
Affiliation(s)
- Robert Walder
- JILA, National Institute of Standards and Technology , and University of Colorado, Boulder, Colorado 80309, United States
| | - William J Van Patten
- JILA, National Institute of Standards and Technology , and University of Colorado, Boulder, Colorado 80309, United States
| | - Ayush Adhikari
- JILA, National Institute of Standards and Technology , and University of Colorado, Boulder, Colorado 80309, United States
| | - Thomas T Perkins
- JILA, National Institute of Standards and Technology , and University of Colorado, Boulder, Colorado 80309, United States
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado , Boulder, Colorado 80309, United States
| |
Collapse
|
36
|
Abstract
The three-dimensional structure of DNA is highly susceptible to changes by mechanical and biochemical cues in vivo and in vitro. In particular, large increases in base pair spacing compared to regular B-DNA are effected by mechanical (over)stretching and by intercalation of compounds that are widely used in biophysical/chemical assays and drug treatments. We present single-molecule experiments and a three-state statistical mechanical model that provide a quantitative understanding of the interplay between B-DNA, overstretched DNA and intercalated DNA. The predictions of this model include a hitherto unconfirmed hyperstretched state, twice the length of B-DNA. Our force-fluorescence experiments confirm this hyperstretched state and reveal its sequence dependence. These results pin down the physical principles that govern DNA mechanics under the influence of tension and biochemical reactions. A predictive understanding of the possibilities and limitations of DNA extension can guide refined exploitation of DNA in, e.g., programmable soft materials and DNA origami applications. The mechanics and structural transitions of DNA are important to many essential processes inside living cells. Here the authors combine theory and single-molecule experiments to show that intercalator binding stabilises a new structural state of DNA: hyperstretched DNA.
Collapse
|
37
|
Garai A, Mogurampelly S, Bag S, Maiti PK. Overstretching of B-DNA with various pulling protocols: Appearance of structural polymorphism and S-DNA. J Chem Phys 2017; 147:225102. [DOI: 10.1063/1.4991862] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Ashok Garai
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Department of Physics, The LNM Institute of Information Technology, Jamdoli, Jaipur 302031, India
| | - Santosh Mogurampelly
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Saientan Bag
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Prabal K. Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| |
Collapse
|
38
|
Chen J, Tang Q, Guo S, Lu C, Le S, Yan J. Parallel triplex structure formed between stretched single-stranded DNA and homologous duplex DNA. Nucleic Acids Res 2017; 45:10032-10041. [PMID: 28973442 PMCID: PMC5622322 DOI: 10.1093/nar/gkx628] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/11/2017] [Indexed: 02/01/2023] Open
Abstract
The interaction between the single-stranded DNA and the homologous duplex DNA is essential for DNA homologous repair. Here, we report that parallel triplex structure can form spontaneously between a mechanically extended ssDNA and a homologous dsDNA in protein-free condition. The triplex has a contour length close to that of a B-form DNA duplex and remains stable after force is released. The binding energy between the ssDNA and the homologous dsDNA in the triplex is estimated to be comparable to the basepairing energy in a B-form dsDNA. As ssDNA is in a similar extended conformation within recombinase-coated nucleoprotein filaments, we propose that the parallel triplex may form and serve as an intermediate during recombinase-catalyzed homologous joint formation.
Collapse
Affiliation(s)
- Jin Chen
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Qingnan Tang
- Department of Physics, National University of Singapore, 117542, Singapore
| | - Shiwen Guo
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Chen Lu
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Centre for Bioimaging Sciences, National University of Singapore, 117546, Singapore
| | - Shimin Le
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Department of Physics, National University of Singapore, 117542, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Department of Physics, National University of Singapore, 117542, Singapore.,Centre for Bioimaging Sciences, National University of Singapore, 117546, Singapore
| |
Collapse
|
39
|
mDia1 senses both force and torque during F-actin filament polymerization. Nat Commun 2017; 8:1650. [PMID: 29162803 PMCID: PMC5698482 DOI: 10.1038/s41467-017-01745-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 10/12/2017] [Indexed: 11/08/2022] Open
Abstract
Formins, an important family of force-bearing actin-polymerizing factors, function as homodimers that bind with the barbed end of actin filaments through a ring-like structure assembled from dimerized FH2 domains. It has been hypothesized that force applied to formin may facilitate transition of the FH2 ring from an inhibitory closed conformation to a permissive open conformation, speeding up actin polymerization. We confirm this hypothesis for mDia1 dependent actin polymerization by stretching a single-actin filament in the absence of profilin using magnetic tweezers, and observe that increasing force from 0.5 to 10 pN can drastically speed up the actin polymerization rate. Further, we find that this force-promoted actin polymerization requires torsionally unconstrained actin filament, suggesting that mDia1 also senses torque. As actin filaments are subject to complex mechanical constraints in living cells, these results provide important insights into how formin senses these mechanical constraints and regulates actin organization accordingly.
Collapse
|
40
|
You H, Le S, Chen H, Qin L, Yan J. Single-molecule Manipulation of G-quadruplexes by Magnetic Tweezers. J Vis Exp 2017. [PMID: 28994776 DOI: 10.3791/56328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Non-canonical nucleic acid secondary structure G-quadruplexes (G4) are involved in diverse cellular processes, such as DNA replication, transcription, RNA processing, and telomere elongation. During these processes, various proteins bind and resolve G4 structures to perform their function. As the function of G4 often depends on the stability of its folded structure, it is important to investigate how G4 binding proteins regulate the stability of G4. This work presents a method to manipulate single G4 molecules using magnetic tweezers, which enables studies of the regulation of G4 binding proteins on a single G4 molecule in real time. In general, this method is suitable for a wide scope of applications in studies for proteins/ligands interactions and regulations on various DNA or RNA secondary structures.
Collapse
Affiliation(s)
- Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology;
| | - Shimin Le
- Mechanobiology Institute, National University of Singapore; Department of Physics, National University of Singapore
| | - Hu Chen
- Mechanobiology Institute, National University of Singapore; Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University
| | - Linyan Qin
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore; Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University; Center for Bioimaging Sciences, National University of Singapore;
| |
Collapse
|
41
|
Chung WJ, Cui Y, Chen CS, Wei WH, Chang RS, Shu WY, Hsu IC. Freezing shortens the lifetime of DNA molecules under tension. J Biol Phys 2017; 43:511-524. [PMID: 28887655 PMCID: PMC5696304 DOI: 10.1007/s10867-017-9466-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 08/16/2017] [Indexed: 12/24/2022] Open
Abstract
DNA samples are commonly frozen for storage. However, freezing can compromise the integrity of DNA molecules. Considering the wide applications of DNA molecules in nanotechnology, changes to DNA integrity at the molecular level may cause undesirable outcomes. However, the effects of freezing on DNA integrity have not been fully explored. To investigate the impact of freezing on DNA integrity, samples of frozen and non-frozen bacteriophage lambda DNA were studied using optical tweezers. Tension (5–35 pN) was applied to DNA molecules to mimic mechanical interactions between DNA and other biomolecules. The integrity of the DNA molecules was evaluated by measuring the time taken for single DNA molecules to break under tension. Mean lifetimes were determined by maximum likelihood estimates and variances were obtained through bootstrapping simulations. Under 5 pN of force, the mean lifetime of frozen samples is 44.3 min with 95% confidence interval (CI) between 36.7 min and 53.6 min while the mean lifetime of non-frozen samples is 133.2 min (95% CI: 97.8–190.1 min). Under 15 pN of force, the mean lifetimes are 10.8 min (95% CI: 7.6–12.6 min) and 78.5 min (95% CI: 58.1–108.9 min). The lifetimes of frozen DNA molecules are significantly reduced, implying that freezing compromises DNA integrity. Moreover, we found that the reduced DNA structural integrity cannot be restored using regular ligation process. These results indicate that freezing can alter the structural integrity of the DNA molecules.
Collapse
Affiliation(s)
- Wei-Ju Chung
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - Yujia Cui
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan.
| | - Chi-Shuo Chen
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - Wesley H Wei
- Department of Computer Science, Tufts University, 419 Boston Avenue, Medford, MA, 02155, USA
| | - Rong-Shing Chang
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - Wun-Yi Shu
- Institute of Statistics, National Tsing Hua University, 101, Section 2, Kuang-Fu road, Hsinchu, 30013, Taiwan
| | - Ian C Hsu
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan.
| |
Collapse
|
42
|
Selvam S, Mandal S, Mao H. Quantification of Chemical and Mechanical Effects on the Formation of the G-Quadruplex and i-Motif in Duplex DNA. Biochemistry 2017; 56:4616-4625. [PMID: 28738141 DOI: 10.1021/acs.biochem.7b00279] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The formation of biologically significant tetraplex DNA species, such as G-quadruplexes and i-motifs, is affected by chemical (ions and pH) and mechanical [superhelicity (σ) and molecular crowding] factors. Because of the extremely challenging experimental conditions, the relative importance of these factors on tetraplex folding is unknown. In this work, we quantitatively evaluated the chemical and mechanical effects on the population dynamics of DNA tetraplexes in the insulin-linked polymorphic region using magneto-optical tweezers. By mechanically unfolding individual tetraplexes, we found that ions and pH have the largest effects on the formation of the G-quadruplex and i-motif, respectively. Interestingly, superhelicity has the second largest effect followed by molecular crowding conditions. While chemical effects are specific to tetraplex species, mechanical factors have generic influences. The predominant effect of chemical factors can be attributed to the fact that they directly change the stability of a specific tetraplex, whereas the mechanical factors, superhelicity in particular, reduce the stability of the competing species by changing the kinetics of the melting and annealing of the duplex DNA template in a nonspecific manner. The substantial dependence of tetraplexes on superhelicity provides strong support that DNA tetraplexes can serve as topological sensors to modulate fundamental cellular processes such as transcription.
Collapse
Affiliation(s)
- Sangeetha Selvam
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| | - Shankar Mandal
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| | - Hanbin Mao
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| |
Collapse
|
43
|
Bao L, Zhang X, Shi YZ, Wu YY, Tan ZJ. Understanding the Relative Flexibility of RNA and DNA Duplexes: Stretching and Twist-Stretch Coupling. Biophys J 2017; 112:1094-1104. [PMID: 28355538 DOI: 10.1016/j.bpj.2017.02.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/02/2017] [Accepted: 02/21/2017] [Indexed: 01/16/2023] Open
Abstract
The flexibility of double-stranded (ds) RNA and dsDNA is crucial for their biological functions. Recent experiments have shown that the flexibility of dsRNA and dsDNA can be distinctively different in the aspects of stretching and twist-stretch coupling. Although various studies have been performed to understand the flexibility of dsRNA and dsDNA, there is still a lack of deep understanding of the distinctive differences in the flexibility of dsRNA and dsDNA helices as pertains to their stretching and twist-stretch coupling. In this work, we have explored the relative flexibility in stretching and twist-stretch coupling between dsRNA and dsDNA by all-atom molecular dynamics simulations. The calculated stretch modulus and twist-stretch coupling are in good accordance with the existing experiments. Our analyses show that the differences in stretching and twist-stretch coupling between dsRNA and dsDNA helices are mainly attributed to their different (A- and B-form) helical structures. Stronger basepair inclination and slide in dsRNA is responsible for the apparently weaker stretching rigidity versus that of dsDNA, and the opposite twist-stretch coupling for dsRNA and dsDNA is also attributed to the stronger basepair inclination in dsRNA than in dsDNA. Our calculated macroscopic elastic parameters and microscopic analyses are tested and validated by different force fields for both dsRNA and dsDNA.
Collapse
Affiliation(s)
- Lei Bao
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xi Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Zhou Shi
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China; Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Yuan-Yan Wu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China; College of Physical Science and Technology, Yangzhou University, Yangzhou, China
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
| |
Collapse
|
44
|
Liu C, Zhai W, Gong H, Liu Y, Chen H. Effect of fluoride ion on the stability of DNA hairpin. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
45
|
Singh J, Purohit PK. Structural transitions in torsionally constrained DNA and their dependence on solution electrostatics. Acta Biomater 2017; 55:214-225. [PMID: 28365483 DOI: 10.1016/j.actbio.2017.03.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/13/2017] [Accepted: 03/28/2017] [Indexed: 02/05/2023]
Abstract
Experimental studies on single molecules of DNA have reported a rich variety of structural transitions, including coexistence of three phases, in a torsionally constrained molecule. A comprehensive knowledge of these structural transitions is useful for unraveling the in vivo and in vitro behavior of DNA. Our objective is to understand the structural transitions in a torsionally constrained DNA molecule when it is pulled using optical or magnetic tweezers. We use foundational concepts from the Zimm-Bragg helix-coil transition theory and merge them with ideas from the theory of fluctuating elastic rods to model the mechanics of DNA. We also account for the electrostatic interactions between the ions and the negatively charged phosphate backbone of DNA. Using our model, we calculate the force and torque corresponding to the overstretching transition characterized by a 70% jump in the contour length of the molecule and examine the effect of salt concentration on this transition. We also deduce conditions under which the co-existence of B-, S- and P-DNA is possible. We examine how the cooperativity parameter for each transition affects the force-extension curve or torque-rotation curve. We attempt to rationalize the non-monotonic dependence of external work done on the ion concentration by connecting it to the electrostatic dependence of the interfacial energy between two phases of DNA. Our theoretical results are in agreement with multiple experiments documented in the literature and they generate falsifiable predictions that can be tested in new experiments. STATEMENT OF SIGNIFICANCE The overarching objective of this paper is to explore the implications of variation in ion concentration on the structural transitions driven by external forces in a torsionally constrained DNA molecule. A comprehensive understanding of the phase behavior of torsionally constrained DNA is useful because DNA in cells is tightly packaged and is acted upon by molecular machines in different ionic environments. We examine the mechanics of the overstretching transition, characterized by a 70% jump in contour length, wherein a mixture of B- and S-DNA converts into a mixture of S- and P-DNA through a triple point in the phase diagram. Our results are corroborated by experimental data at every step and we make predictions that are experimentally verifiable.
Collapse
Affiliation(s)
- Jaspreet Singh
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Prashant K Purohit
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
46
|
Abraham Punnoose J, Ma Y, Li Y, Sakuma M, Mandal S, Nagasawa K, Mao H. Adaptive and Specific Recognition of Telomeric G-Quadruplexes via Polyvalency Induced Unstacking of Binding Units. J Am Chem Soc 2017; 139:7476-7484. [PMID: 28505453 DOI: 10.1021/jacs.7b00607] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Targeting DNA G-quadruplexes using small-molecule ligands has shown to modulate biological functions mediated by G-quadruplexes inside cells. Given >716 000 G-quadruplex hosting sites in human genome, the specific binding of ligands to quadruplex becomes problematic. Here, we innovated a polyvalency based mechanism to specifically target multiple telomeric G-quadruplexes. We synthesized a tetrameric telomestatin derivative and evaluated its complex polyvalent binding with multiple G-quadruplexes by single-molecule mechanical unfolding in laser tweezers. We found telomestatin tetramer binds to multimeric telomeric G-quadruplexes >40 times stronger than monomeric quadruplexes, which can be ascribed to the polyvalency induced unstacking of binding units (or PIU binding) for G-quadruplexes. While stacking of telomestatin units in the tetramer imparts steric hindrance for the ligand to access stand-alone G-quadruplexes, the stacking disassembles to accommodate the potent polyvalent binding between the tetramer ligand and multimeric G-quadruplexes. We anticipate this adaptive PIU binding offers a generic mechanism to selectively target polymeric biomolecules prevalent inside cells.
Collapse
Affiliation(s)
- Jibin Abraham Punnoose
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| | - Yue Ma
- Department of Biotechnology and Life Science Faculty of Technology, Tokyo University of Agriculture and Technology (TUAT) , 2-14-16 Naka-cho, Koganeishi, Tokyo 184-8588, Japan
| | - Yuanyuan Li
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| | - Mai Sakuma
- Department of Biotechnology and Life Science Faculty of Technology, Tokyo University of Agriculture and Technology (TUAT) , 2-14-16 Naka-cho, Koganeishi, Tokyo 184-8588, Japan
| | - Shankar Mandal
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science Faculty of Technology, Tokyo University of Agriculture and Technology (TUAT) , 2-14-16 Naka-cho, Koganeishi, Tokyo 184-8588, Japan
| | - Hanbin Mao
- Department of Chemistry and Biochemistry, Kent State University , Kent, Ohio 44242, United States
| |
Collapse
|
47
|
Theoretical Methods for Studying DNA Structural Transitions under Applied Mechanical Constraints. Polymers (Basel) 2017; 9:polym9020074. [PMID: 30970752 PMCID: PMC6432069 DOI: 10.3390/polym9020074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 02/14/2017] [Indexed: 11/24/2022] Open
Abstract
Recent progress in single-molecule manipulation technologies has made it possible to exert force and torque on individual DNA biopolymers to probe their mechanical stability and interaction with various DNA-binding proteins. It was revealed in these experiments that the DNA structure and formation of nucleoprotein complexes by DNA-architectural proteins can be strongly modulated by an intricate interplay between the entropic elasticity of DNA and its global topology, which is closely related to the mechanical constraints applied to the DNA. Detailed understanding of the physical processes underlying the DNA behavior observed in single-molecule experiments requires the development of a general theoretical framework, which turned out to be a rather challenging task. Here, we review recent advances in theoretical methods that can be used to interpret single-molecule manipulation experiments on DNA.
Collapse
|
48
|
Zhu YL, Lu ZY, Sun ZY. The mechanism of the emergence of distinct overstretched DNA states. J Chem Phys 2016; 144:024901. [PMID: 26772584 DOI: 10.1063/1.4939623] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Although multiple overstretched DNA states were identified in experiments, the mechanism of the emergence of distinct states is still unclear. Molecular dynamics simulation is an ideal tool to clarify the mechanism, but the force loading rates in stretching achieved by conventional all-atom DNA models are much faster, which essentially affect overstretching states. We employed a modified coarse-grained DNA model with an unprecedented low loading rate in simulations to study the overstretching transitions of end-opened double-stranded DNA. We observed two-strand peeling off for DNA with low stability and the S-DNA with high stability under tension. By introducing a melting-forbidden model which prevents base-pair breaking, we still observed the overstretching transition induced by the formation of S-DNA due to the change of dihedral angle. Hence, we confirmed that the competition between the two strain-softening manners, i.e., base-pair breaking and dihedral angle variation, results in the emergence of distinct overstretched DNA states.
Collapse
Affiliation(s)
- You-Liang Zhu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Zhao-Yan Sun
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| |
Collapse
|
49
|
Probing the mechanical properties, conformational changes, and interactions of nucleic acids with magnetic tweezers. J Struct Biol 2016; 197:26-36. [PMID: 27368129 DOI: 10.1016/j.jsb.2016.06.022] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 05/06/2016] [Accepted: 06/28/2016] [Indexed: 11/21/2022]
Abstract
Nucleic acids are central to the storage and transmission of genetic information. Mechanical properties, along with their sequence, both enable and fundamentally constrain the biological functions of DNA and RNA. For small deformations from the equilibrium conformations, nucleic acids are well described by an isotropic elastic rod model. However, external forces and torsional strains can induce conformational changes, giving rise to a complex force-torque phase diagram. This review focuses on magnetic tweezers as a powerful tool to precisely determine both the elastic parameters and conformational transitions of nucleic acids under external forces and torques at the single-molecule level. We review several variations of magnetic tweezers, in particular conventional magnetic tweezers, freely orbiting magnetic tweezers and magnetic torque tweezers, and discuss their characteristic capabilities. We then describe the elastic rod model for DNA and RNA and discuss conformational changes induced by mechanical stress. The focus lies on the responses to torque and twist, which are crucial in the mechanics and interactions of nucleic acids and can directly be measured using magnetic tweezers. We conclude by highlighting several recent studies of nucleic acid-protein and nucleic acid-small-molecule interactions as further applications of magnetic tweezers and give an outlook of some exciting developments to come.
Collapse
|
50
|
King GA, Peterman EJG, Wuite GJL. Unravelling the structural plasticity of stretched DNA under torsional constraint. Nat Commun 2016; 7:11810. [PMID: 27263853 PMCID: PMC4897764 DOI: 10.1038/ncomms11810] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 04/29/2016] [Indexed: 01/26/2023] Open
Abstract
Regions of the genome are often held under torsional constraint. Nevertheless, the influence of such constraint on DNA-protein interactions during genome metabolism is still poorly understood. Here using a combined optical tweezers and fluorescence microscope, we quantify and explain how torsional constraint influences the structural stability of DNA under applied tension. We provide direct evidence that concomitant basepair melting and helical unwinding can occur in torsionally constrained DNA at forces >∼50 pN. This striking result indicates that local changes in linking number can be absorbed by the rest of the DNA duplex. We also present compelling new evidence that an overwound DNA structure (likely P-DNA) is created (alongside underwound structures) at forces >∼110 pN. These findings substantiate previous theoretical predictions and highlight a remarkable structural plasticity of torsionally constrained DNA. Such plasticity may be required in vivo to absorb local changes in linking number in DNA held under torsional constraint.
Collapse
Affiliation(s)
- Graeme A King
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| |
Collapse
|