1
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Thiede J, Schneeberger T, Iacovache I, Langenegger SM, Zuber B, Häner R. Supramolecular assembly of phenanthrene-DNA conjugates into light-harvesting nanospheres. NEW J CHEM 2024; 48:15731-15734. [PMID: 39234596 PMCID: PMC11367589 DOI: 10.1039/d4nj02411g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Accepted: 08/23/2024] [Indexed: 09/06/2024]
Abstract
The self-assembly of highly functionalized phenanthrene-DNA conjugates into supramolecular nanostructures is presented. DNA oligomers modified with phenanthrene residues at the 3'-end and internal positions self-assemble into spherical nanostructures. The nanospheres exhibit light-harvesting properties. Upon irradiation of phenanthrene, the excitation energy is transferred along phenanthrene units, resulting in phenanthrene-pyrene exciplex formation.
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Affiliation(s)
- Jan Thiede
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland https://www.haener.dcbp.unibe.ch
| | - Thomas Schneeberger
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland https://www.haener.dcbp.unibe.ch
| | - Ioan Iacovache
- Institute of Anatomy, University of Bern Baltzerstrasse 2 CH-3012 Bern Switzerland
| | - Simon M Langenegger
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland https://www.haener.dcbp.unibe.ch
| | - Benoît Zuber
- Institute of Anatomy, University of Bern Baltzerstrasse 2 CH-3012 Bern Switzerland
| | - Robert Häner
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland https://www.haener.dcbp.unibe.ch
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2
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Coste A, Slejko E, Zavadlav J, Praprotnik M. Developing an Implicit Solvation Machine Learning Model for Molecular Simulations of Ionic Media. J Chem Theory Comput 2024; 20:411-420. [PMID: 38118122 PMCID: PMC10782447 DOI: 10.1021/acs.jctc.3c00984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 12/22/2023]
Abstract
Molecular dynamics (MD) simulations of biophysical systems require accurate modeling of their native environment, i.e., aqueous ionic solution, as it critically impacts the structure and function of biomolecules. On the other hand, the models should be computationally efficient to enable simulations of large spatiotemporal scales. Here, we present the deep implicit solvation model for sodium chloride solutions that satisfies both requirements. Owing to the use of the neural network potential, the model can capture the many-body potential of mean force, while the implicit water treatment renders the model inexpensive. We demonstrate our approach first for pure ionic solutions with concentrations ranging from physiological to 2 M. We then extend the model to capture the effective ion interactions in the vicinity and far away from a DNA molecule. In both cases, the structural properties are in good agreement with all-atom MD, showcasing a general methodology for the efficient and accurate modeling of ionic media.
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Affiliation(s)
- Amaury Coste
- Laboratory
for Molecular Modeling, National Institute of Chemistry, Ljubljana SI-1001, Slovenia
| | - Ema Slejko
- Laboratory
for Molecular Modeling, National Institute of Chemistry, Ljubljana SI-1001, Slovenia
- Department
of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana SI-1000, Slovenia
| | - Julija Zavadlav
- Professorship
of Multiscale Modeling of Fluid Materials, TUM School of Engineering
and Design, Technical University of Munich, Garching Near Munich DE-85748, Germany
| | - Matej Praprotnik
- Laboratory
for Molecular Modeling, National Institute of Chemistry, Ljubljana SI-1001, Slovenia
- Department
of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana SI-1000, Slovenia
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3
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Thiede J, Rothenbühler S, Iacovache I, Langenegger SM, Zuber B, Häner R. Supramolecular assembly of pyrene-DNA conjugates: influence of pyrene substitution pattern and implications for artificial LHCs. Org Biomol Chem 2023; 21:7908-7912. [PMID: 37750811 PMCID: PMC10566252 DOI: 10.1039/d3ob01375h] [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: 08/28/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023]
Abstract
The supramolecular self-assembly of pyrene-DNA conjugates into nanostructures is presented. DNA functionalized with different types of pyrene isomers at the 3'-end self-assemble into nano-objects. The shape of the nanostructures is influenced by the type of pyrene isomer appended to the DNA. Multilamellar vesicles are observed with the 1,6- and 1,8-isomers, whereas conjugates of the 2,7-isomer exclusively assemble into spherical nanoparticles. Self-assembled nano-spheres obtained with the 2,7-dialkynyl pyrene isomer were used for the construction of an artificial light-harvesting complex (LHC) in combination with Cy3 as the energy acceptor.
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Affiliation(s)
- Jan Thiede
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Simon Rothenbühler
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Ioan Iacovache
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, CH-3012 Bern, Switzerland
| | - Simon M Langenegger
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Benoît Zuber
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, CH-3012 Bern, Switzerland
| | - Robert Häner
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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4
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He W, Qiu X, Kirmizialtin S. Sequence-Dependent Orientational Coupling and Electrostatic Attraction in Cation-Mediated DNA-DNA Interactions. J Chem Theory Comput 2023; 19:6827-6838. [PMID: 37728274 PMCID: PMC10569048 DOI: 10.1021/acs.jctc.3c00520] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Indexed: 09/21/2023]
Abstract
Condensation of DNA is vital for its biological functions and controlled nucleic acid assemblies. However, the mechanisms of DNA condensation are not fully understood due to the inability of experiments to access cation distributions and the complex interplay of energetic and entropic forces during assembly. By constructing free energy surfaces using exhaustive sampling and detailed analysis of cation distributions, we elucidate the mechanism of DNA condensation in different salt conditions and with different DNA sequences. We found that DNA condensation is facilitated by the correlated dynamics of the localized cations at the grooves of DNA helices. These dynamics are strongly dependent on the salt conditions and DNA sequences. In the presence of magnesium ions, major groove binding facilitates attraction. In contrast, in the presence of polyvalent cations, minor groove binding serves to create charge patterns, leading to condensation. Our findings present a novel advancement in the field and have broad implications for understanding and controlling nucleic acid complexes in vivo and in vitro.
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Affiliation(s)
- Weiwei He
- Chemistry
Program, Science Division, New York University
Abu Dhabi, Abu Dhabi 129188, United
Arab Emirates
- Department
of Chemistry, New York University, New York, New York 10012, United States
| | - Xiangyun Qiu
- Department
of Physics, George Washington University, Washington, District of
Columbia 20052, United States
| | - Serdal Kirmizialtin
- Chemistry
Program, Science Division, New York University
Abu Dhabi, Abu Dhabi 129188, United
Arab Emirates
- Department
of Chemistry, New York University, New York, New York 10012, United States
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5
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Leal FCB, Gomes MAF. Unfolding of crumpled thin sheets. Phys Rev E 2022; 106:025002. [PMID: 36110023 DOI: 10.1103/physreve.106.025002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Crumpled thin sheets are complex fractal structures whose physical properties are influenced by a hierarchy of ridges. In this paper, we report experiments that measure the stress-strain relation and show the coexistence of phases in the stretching of crumpled surfaces. The pull stress showed a change from a linear Hookean regime to a sublinear scaling with an exponent of 0.65±0.03, which is identified with the Hurst exponent of the crumpled sheets. The stress fluctuations are studied. The statistical distribution of force peaks is analyzed. It is shown that the unpacking of crumpled sheets is guided by a hierarchical order of ridges.
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Affiliation(s)
- F C B Leal
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
| | - M A F Gomes
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
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6
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Rothenbühler S, Iacovache I, Langenegger SM, Zuber B, Häner R. Complex DNA Architectonics─Self-Assembly of Amphiphilic Oligonucleotides into Ribbons, Vesicles, and Asterosomes. Bioconjug Chem 2022; 34:70-77. [PMID: 35357155 PMCID: PMC9854621 DOI: 10.1021/acs.bioconjchem.2c00077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The precise arrangement of structural subunits is a key factor for the proper shape and function of natural and artificial supramolecular assemblies. In DNA nanotechnology, the geometrically well-defined double-stranded DNA scaffold serves as an element of spatial control for the precise arrangement of functional groups. Here, we describe the supramolecular assembly of chemically modified DNA hybrids into diverse types of architectures. An amphiphilic DNA duplex serves as the sole structural building element of the nanosized supramolecular structures. The morphology of the assemblies is governed by a single subunit of the building block. The chemical nature of this subunit, i.e., polyethylene glycols of different chain length or a carbohydrate moiety, exerts a dramatic influence on the architecture of the assemblies. Cryo-electron microscopy revealed the arrangement of the individual DNA duplexes within the different constructs. Thus, the morphology changes from vesicles to ribbons with increasing length of a linear polyethylene glycol. Astoundingly, attachment of a N-acetylgalactosamine carbohydrate to the DNA duplex moiety produces an unprecedented type of star-shaped architecture. The novel DNA architectures presented herein imply an extension of the current concept of DNA materials and shed new light on the fast-growing field of DNA nanotechnology.
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Affiliation(s)
- Simon Rothenbühler
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Ioan Iacovache
- Institute
of Anatomy, University of Bern, Baltzerstrasse 2, CH-3012 Bern, Switzerland
| | - Simon M. Langenegger
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Benoît Zuber
- Institute
of Anatomy, University of Bern, Baltzerstrasse 2, CH-3012 Bern, Switzerland
| | - Robert Häner
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland,
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7
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Mohamed A, Walsh R, Cherif M, Hafez HA, Ropagnol X, Vidal F, Perreault J, Ozaki T. High-sensitivity small-molecule detection of microcystin-LR cyano-toxin using a terahertz-aptamer biosensor. Analyst 2021; 146:7583-7592. [PMID: 34780591 DOI: 10.1039/d1an01577j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We demonstrate the rapid and highly sensitive detection of a small molecule, microcystin-LR (MC-LR) toxin using an aptasensor based on a terahertz (THz) emission technique named the terahertz chemical microscope (TCM). The main component of the TCM is the sensing plate, which consists of a thin silicon layer deposited on a sapphire substrate, with a natural SiO2 layer formed on the top of the Si layer. The DNA aptamer is linked to the oxidized top surface of the silicon layer by a one-step reaction (click chemistry) between the DBCO-labeled aptamer and an azido group that binds to the surface. Using density functional theory (DFT) calculations, the number of active sites on the surface has been estimated to be 3.8 × 1013 cm-2. Aptamer immobilization and MC-LR binding have been optimized by adjusting the aptamer concentration and the binding buffer composition. When MC-LR binds with the DNA aptamer, it causes a change in the chemical potential at the surface of the sensing plate, which leads to a change in the amplitude of the THz signal. Compared with other bio-sensing methods such as surface plasmon resonance (SPR), TCM is a rapid assay that can be completed in 15 min (10 min incubation and 5 min data acquisition). Moreover, our results show that the aptamer-based TCM can detect MC-LR with an excellent detection limit of 50 ng L-1, which is 20 times more sensitive compared with SPR measurements of MC-LR.
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Affiliation(s)
- Ahmed Mohamed
- Institut National de la Recherche Scientifique - Énergie Matériaux Télécommunications, Varennes, Québec J3X 1S2, Canada.
| | - Ryan Walsh
- INRS Centre Armand-Frappier Santé Biotechnologie, 531 boulevards des Prairies, Laval, Québec, Canada
| | - Mohamed Cherif
- Institut National de la Recherche Scientifique - Énergie Matériaux Télécommunications, Varennes, Québec J3X 1S2, Canada.
| | - Hassan A Hafez
- Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - Xavier Ropagnol
- Institut National de la Recherche Scientifique - Énergie Matériaux Télécommunications, Varennes, Québec J3X 1S2, Canada. .,Département de génie électrique, École de technologie supérieure (ÉTS), Montréal, Québec, H3C 1 K3, Canada
| | - François Vidal
- Institut National de la Recherche Scientifique - Énergie Matériaux Télécommunications, Varennes, Québec J3X 1S2, Canada.
| | - Jonathan Perreault
- INRS Centre Armand-Frappier Santé Biotechnologie, 531 boulevards des Prairies, Laval, Québec, Canada
| | - Tsuneyuki Ozaki
- Institut National de la Recherche Scientifique - Énergie Matériaux Télécommunications, Varennes, Québec J3X 1S2, Canada.
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8
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Lee K, Tripathi A. Parallel DNA Extraction From Whole Blood for Rapid Sample Generation in Genetic Epidemiological Studies. Front Genet 2020; 11:374. [PMID: 32411178 PMCID: PMC7201099 DOI: 10.3389/fgene.2020.00374] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/26/2020] [Indexed: 01/12/2023] Open
Abstract
Large-scale genetic epidemiological studies require high-quality analysis of samples such as blood or saliva from multiple patients, which is challenging at the point of care. To expand these studies’ impact, minimal sample storage time and less complex extraction of a substantial quantity and good purity of DNA or RNA for downstream applications are necessary. Here, a simple microfluidics-based system that performs genomic DNA (gDNA) extraction from whole blood was developed. In this system, a mixture of blood lysate, paramagnetic beads, and binding buffer are first placed into the input well. Then, the gDNA-bound paramagnetic beads are pulled using a magnet through a central channel containing a wash buffer to the output well, which contains elution buffer. The gDNA is eluted at 55°C off the chip. The 40-minute microfluidic protocol extracts gDNA from six samples simultaneously and requires an input of 4 μL of diluted blood and a total reagent volume of 75 μL per reaction. Techniques including quantitative PCR (qPCR) and spectrofluorimetry were used to test the purity and quantity of gDNA eluted from the chip following extraction. Bead transport and molecular diffusional analysis showed that an input of less than 4 ng of gDNA (∼667 white blood cells) is optimal for on-chip extraction. There was no observable transport of inhibitors into the eluate that would greatly affect qPCR, and a sample was successfully prepared for next-generation sequencing (NGS). The microfluidics-based extraction of DNA from whole blood described here is paramount for future work in DNA-based point-of-care diagnostics and NGS library workflows.
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Affiliation(s)
- Kiara Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Anubhav Tripathi
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
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9
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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.
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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
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10
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Schneider A, Niemeyer CM. DNA Surface Technology: From Gene Sensors to Integrated Systems for Life and Materials Sciences. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201811713] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Ann‐Kathrin Schneider
- Institute for Biological Interfaces (IBG 1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 76344 Eggenstein-Leopoldshafen Germany
| | - Christof M. Niemeyer
- Institute for Biological Interfaces (IBG 1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 76344 Eggenstein-Leopoldshafen Germany
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11
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Schneider A, Niemeyer CM. DNA Surface Technology: From Gene Sensors to Integrated Systems for Life and Materials Sciences. Angew Chem Int Ed Engl 2018; 57:16959-16967. [DOI: 10.1002/anie.201811713] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/15/2018] [Indexed: 01/21/2023]
Affiliation(s)
- Ann‐Kathrin Schneider
- Institute for Biological Interfaces (IBG 1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 76344 Eggenstein-Leopoldshafen Germany
| | - Christof M. Niemeyer
- Institute for Biological Interfaces (IBG 1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 76344 Eggenstein-Leopoldshafen Germany
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12
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Wu S, Li C, Zheng Q, Xu L. Modelling DNA extension and fragmentation in contractive microfluidic devices: a Brownian dynamics and computational fluid dynamics approach. SOFT MATTER 2018; 14:8780-8791. [PMID: 30338769 DOI: 10.1039/c8sm00863a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fragmenting DNA into short pieces is an essential manipulation in many biological studies, ranging from genome sequencing to molecular diagnosis. Among various DNA fragmentation methods, microfluidic hydrodynamic DNA fragmentation has huge advantages especially in terms of handling small-volume samples and being integrated into automatic and all-in-one DNA analysis equipment. Despite the fast progress in experimental studies and applications, a systematic understanding of how DNA molecules are distributed, stretched and fragmented in a confined microfluidic field is still lacking. In this work, we investigate the extension and fragmentation of DNA in a typical contractive microfluidic field, which consists of a shear flow-dominated area and an elongational flow-dominated area, using the Brownian dynamics-computational fluid dynamics method. Our results show that the shear flow at the straight part of the microfluidic channel and the elongational flow at the contractive bottleneck together determine the performance of DNA fragmentation. The average fragment size of DNA decreases with the increase of the strain rate of the elongational flow, and the upstream shear flow can significantly precondition the conformation of DNA to produce shorter and more uniform fragments. A systematic study of the dynamics of DNA fragmentation shows that DNA tends to break at the mid-point when the strain rate of elongational flow is small, and the breakage point largely deviates from the midpoint as the strain rate increases. Our simulation of the thorough DNA fragmentation process in a realistic microfluidic field agrees well with experimental results. We expect that our study can shed new light on the development of future microfluidic devices for DNA fragmentation and integrated DNA analysis devices.
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Affiliation(s)
- Shuyi Wu
- Center for Nano and Micro Mechanics, School of Aerospace Engineering, Tsinghua University, Beijing, China.
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13
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Naji A, Hejazi K, Mahgerefteh E, Podgornik R. Charged nanorods at heterogeneously charged surfaces. J Chem Phys 2018; 149:134702. [PMID: 30292214 DOI: 10.1063/1.5044391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the spatial and orientational distribution of charged nanorods (rodlike counterions) as well as the effective interaction mediated by them between two plane-parallel surfaces that carry fixed (quenched) heterogeneous charge distributions. The nanorods are assumed to have an internal charge distribution, specified by a multivalent monopolar moment and a finite quadrupolar moment, and the quenched surface charge is assumed to be randomly distributed with equal mean and variance on the two surfaces. While equally charged surfaces are known to repel within the traditional mean-field theories, the presence of multivalent counterions has been shown to cause attractive interactions between uniformly charged surfaces due to the prevalence of strong electrostatic couplings that grow rapidly with the counterion valency. We show that the combined effects due to electrostatic correlations (caused by the coupling between the mean surface field and the multivalent, monopolar, charge valency of counterions) as well as the disorder-induced interactions (caused by the coupling between the surface disorder field and the quadrupolar moment of counterions) lead to much stronger attractive interactions between two randomly charged surfaces. The interaction profile turns out to be a nonmonotonic function of the intersurface separation, displaying an attractive minimum at relatively small separations, where the ensuing attraction can exceed the maximum strong-coupling attraction (produced by multivalent monopolar counterions between uniformly charged surfaces) by more than an order of magnitude.
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Affiliation(s)
- Ali Naji
- School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran
| | - Kasra Hejazi
- School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran
| | - Elnaz Mahgerefteh
- School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran
| | - Rudolf Podgornik
- School of Physical Sciences and Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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14
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Jin L, Shi YZ, Feng CJ, Tan YL, Tan ZJ. Modeling Structure, Stability, and Flexibility of Double-Stranded RNAs in Salt Solutions. Biophys J 2018; 115:1403-1416. [PMID: 30236782 DOI: 10.1016/j.bpj.2018.08.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/10/2018] [Accepted: 08/24/2018] [Indexed: 11/16/2022] Open
Abstract
Double-stranded (ds) RNAs play essential roles in many processes of cell metabolism. The knowledge of three-dimensional (3D) structure, stability, and flexibility of dsRNAs in salt solutions is important for understanding their biological functions. In this work, we further developed our previously proposed coarse-grained model to predict 3D structure, stability, and flexibility for dsRNAs in monovalent and divalent ion solutions through involving an implicit structure-based electrostatic potential. The model can make reliable predictions for 3D structures of extensive dsRNAs with/without bulge/internal loops from their sequences, and the involvement of the structure-based electrostatic potential and corresponding ion condition can improve the predictions for 3D structures of dsRNAs in ion solutions. Furthermore, the model can make good predictions for thermal stability for extensive dsRNAs over the wide range of monovalent/divalent ion concentrations, and our analyses show that the thermally unfolding pathway of dsRNA is generally dependent on its length as well as its sequence. In addition, the model was employed to examine the salt-dependent flexibility of a dsRNA helix, and the calculated salt-dependent persistence lengths are in good accordance with experiments.
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Affiliation(s)
- Lei Jin
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Zhou Shi
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Chen-Jie Feng
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Lan Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
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15
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Zhang ZL, Wu YY, Xi K, Sang JP, Tan ZJ. Divalent Ion-Mediated DNA-DNA Interactions: A Comparative Study of Triplex and Duplex. Biophys J 2017; 113:517-528. [PMID: 28793207 DOI: 10.1016/j.bpj.2017.06.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/08/2017] [Accepted: 06/12/2017] [Indexed: 12/21/2022] Open
Abstract
Ion-mediated interaction between DNAs is essential for DNA condensation, and it is generally believed that monovalent and nonspecifically binding divalent cations cannot induce the aggregation of double-stranded (ds) DNAs. Interestingly, recent experiments found that alkaline earth metal ions such as Mg2+ can induce the aggregation of triple-stranded (ts) DNAs, although there is still a lack of deep understanding of the surprising findings at the microscopic level. In this work, we employed all-atom dynamic simulations to directly calculate the potentials of mean force (PMFs) between tsDNAs, between dsDNAs, and between tsDNA and dsDNA in Mg2+ solutions. Our calculations show that the PMF between tsDNAs is apparently attractive and becomes more strongly attractive at higher [Mg2+], although the PMF between dsDNAs cannot become apparently attractive even at high [Mg2+]. Our analyses show that Mg2+ internally binds into grooves and externally binds to phosphate groups for both tsDNA and dsDNA, whereas the external binding of Mg2+ is much stronger for tsDNA. Such stronger external binding of Mg2+ for tsDNA favors more apparent ion-bridging between helices than for dsDNA. Furthermore, our analyses illustrate that bridging ions, as a special part of external binding ions, are tightly and positively coupled to ion-mediated attraction between DNAs.
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Affiliation(s)
- Zhong-Liang Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Yuan-Yan Wu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China; College of Physical Science and Technology, Yangzhou University, Yangzhou, China
| | - Kun Xi
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Jian-Ping Sang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
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Ralph SF. Frontiers in Nucleic Acid Nanotechnology. NANOMATERIALS 2015; 5:750-754. [PMID: 28347033 PMCID: PMC5312903 DOI: 10.3390/nano5020750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 05/07/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen F Ralph
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong 2522, NSW, Australia.
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