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Lin YY, Müller P, Karagianni E, Hepp N, Mueller-Planitz F, Vanderlinden W, Lipfert J. Epigenetic Histone Modifications H3K36me3 and H4K5/8/12/16ac Induce Open Polynucleosome Conformations via Different Mechanisms. J Mol Biol 2024; 436:168671. [PMID: 38908785 DOI: 10.1016/j.jmb.2024.168671] [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] [Received: 02/18/2024] [Revised: 05/28/2024] [Accepted: 06/16/2024] [Indexed: 06/24/2024]
Abstract
Nucleosomes are the basic compaction unit of chromatin and nucleosome structure and their higher-order assemblies regulate genome accessibility. Many post-translational modifications alter nucleosome dynamics, nucleosome-nucleosome interactions, and ultimately chromatin structure and gene expression. Here, we investigate the role of two post-translational modifications associated with actively transcribed regions, H3K36me3 and H4K5/8/12/16ac, in the contexts of tri-nucleosome arrays that provide a tractable model system for quantitative single-molecule analysis, while enabling us to probe nucleosome-nucleosome interactions. Direct visualization by AFM imaging reveals that H3K36me3 and H4K5/8/12/16ac nucleosomes adopt significantly more open and loose conformations than unmodified nucleosomes. Similarly, magnetic tweezers force spectroscopy shows a reduction in DNA outer turn wrapping and nucleosome-nucleosome interactions for the modified nucleosomes. The results suggest that for H3K36me3 the increased breathing and outer DNA turn unwrapping seen in mononucleosomes propagates to more open conformations in nucleosome arrays. In contrast, the even more open structures of H4K5/8/12/16ac nucleosome arrays do not appear to derive from the dynamics of the constituent mononucleosomes, but are driven by reduced nucleosome-nucleosome interactions, suggesting that stacking interactions can overrule DNA breathing of individual nucleosomes. We anticipate that our methodology will be broadly applicable to reveal the influence of other post-translational modifications and to observe the activity of nucleosome remodelers.
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Affiliation(s)
- Yi-Yun Lin
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Peter Müller
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Evdoxia Karagianni
- Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Nicola Hepp
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; Current address: Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Felix Mueller-Planitz
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands; School of Physics and Astronomy, University of Edinburg, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom.
| | - Jan Lipfert
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands.
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Kolbeck PJ, Tišma M, Analikwu BT, Vanderlinden W, Dekker C, Lipfert J. Supercoiling-dependent DNA binding: quantitative modeling and applications to bulk and single-molecule experiments. Nucleic Acids Res 2024; 52:59-72. [PMID: 38000393 PMCID: PMC10783501 DOI: 10.1093/nar/gkad1055] [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: 06/29/2023] [Revised: 10/02/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
DNA stores our genetic information and is ubiquitous in applications, where it interacts with binding partners ranging from small molecules to large macromolecular complexes. Binding is modulated by mechanical strains in the molecule and can change local DNA structure. Frequently, DNA occurs in closed topological forms where topology and supercoiling add a global constraint to the interplay of binding-induced deformations and strain-modulated binding. Here, we present a quantitative model with a straight-forward numerical implementation of how the global constraints introduced by DNA topology modulate binding. We focus on fluorescent intercalators, which unwind DNA and enable direct quantification via fluorescence detection. Our model correctly describes bulk experiments using plasmids with different starting topologies, different intercalators, and over a broad range of intercalator and DNA concentrations. We demonstrate and quantitatively model supercoiling-dependent binding in a single-molecule assay, where we directly observe the different intercalator densities going from supercoiled to nicked DNA. The single-molecule assay provides direct access to binding kinetics and DNA supercoil dynamics. Our model has broad implications for the detection and quantification of DNA, including the use of psoralen for UV-induced DNA crosslinking to quantify torsional tension in vivo, and for the modulation of DNA binding in cellular contexts.
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Affiliation(s)
- Pauline J Kolbeck
- Department of Physics and Center for NanoScience, LMU Munich, Amalienstrasse 54, 80799 Munich, Germany
- Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Miloš Tišma
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Brian T Analikwu
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience, LMU Munich, Amalienstrasse 54, 80799 Munich, Germany
- Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jan Lipfert
- Department of Physics and Center for NanoScience, LMU Munich, Amalienstrasse 54, 80799 Munich, Germany
- Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
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3
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Lin YY, Brouns T, Kolbeck PJ, Vanderlinden W, Lipfert J. High-yield ligation-free assembly of DNA constructs with nucleosome positioning sequence repeats for single-molecule manipulation assays. J Biol Chem 2023; 299:104874. [PMID: 37257819 PMCID: PMC10404619 DOI: 10.1016/j.jbc.2023.104874] [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] [Received: 03/27/2023] [Revised: 05/08/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Force and torque spectroscopy have provided unprecedented insights into the mechanical properties, conformational transitions, and dynamics of DNA and DNA-protein complexes, notably nucleosomes. Reliable single-molecule manipulation measurements require, however, specific and stable attachment chemistries to tether the molecules of interest. Here, we present a functionalization strategy for DNA that enables high-yield production of constructs for torsionally constrained and very stable attachment. The method is based on two subsequent PCRs: first ∼380 bp long DNA strands are generated that contain multiple labels, which are used as "megaprimers" in a second PCR to generate ∼kbp long double-stranded DNA constructs with multiple labels at the respective ends. To achieve high-force stability, we use dibenzocyclooctyne-based click chemistry for covalent attachment to the surface and biotin-streptavidin coupling to the bead. The resulting tethers are torsionally constrained and extremely stable under load, with an average lifetime of 70 ± 3 h at 45 pN. The high yield of the approach enables nucleosome reconstitution by salt dialysis on the functionalized DNA, and we demonstrate proof-of-concept measurements on nucleosome assembly statistics and inner turn unwrapping under force. We anticipate that our approach will facilitate a range of studies of DNA interactions and nucleoprotein complexes under forces and torques.
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Affiliation(s)
- Yi-Yun Lin
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Tine Brouns
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Division of Molecular Imaging and Photonics, KU Leuven, Leuven, Belgium
| | - Pauline J Kolbeck
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
| | - Jan Lipfert
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
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4
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Morioka S, Sato S, Horikoshi N, Kujirai T, Tomita T, Baba Y, Kakuta T, Ogoshi T, Puppulin L, Sumino A, Umeda K, Kodera N, Kurumizaka H, Shibata M. High-Speed Atomic Force Microscopy Reveals Spontaneous Nucleosome Sliding of H2A.Z at the Subsecond Time Scale. NANO LETTERS 2023; 23:1696-1704. [PMID: 36779562 DOI: 10.1021/acs.nanolett.2c04346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nucleosome dynamics, such as nucleosome sliding and DNA unwrapping, are important for gene regulation in eukaryotic chromatin. H2A.Z, a variant of histone H2A that is highly evolutionarily conserved, participates in gene regulation by forming unstable multipositioned nucleosomes in vivo and in vitro. However, the subsecond dynamics of this unstable nucleosome have not been directly visualized under physiological conditions. Here, we used high-speed atomic force microscopy (HS-AFM) to directly visualize the subsecond dynamics of human H2A.Z.1-nucleosomes. HS-AFM videos show nucleosome sliding along 4 nm of DNA within 0.3 s in any direction. This sliding was also visualized in an H2A.Z.1 mutant, in which the C-terminal half was replaced by the corresponding canonical H2A amino acids, indicating that the interaction between the N-terminal region of H2A.Z.1 and the DNA is responsible for nucleosome sliding. These results may reveal the relationship between nucleosome dynamics and gene regulation by histone H2A.Z.
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Affiliation(s)
- Shin Morioka
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Shoko Sato
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Naoki Horikoshi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takuya Tomita
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Yudai Baba
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Takahiro Kakuta
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Tomoki Ogoshi
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Leonardo Puppulin
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Ayumi Sumino
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Kenichi Umeda
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Noriyuki Kodera
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Mikihiro Shibata
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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5
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Abstract
Atomic force microscopy (AFM) is a microscopy technique that uses a sharp probe to trace a sample surface at nanometer resolution. For biological applications, one of its key advantages is its ability to visualize the substructure of single molecules and molecular complexes in an aqueous environment. Here, we describe the application of AFM to determine the secondary and tertiary structure of surface-bound DNA, and its interactions with proteins.
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Affiliation(s)
- Philip J Haynes
- London Centre for Nanotechnology, University College London, London, UK
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, London, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Kavit H S Main
- London Centre for Nanotechnology, University College London, London, UK
- UCL Cancer Institute, University College London, London, UK
| | - Bernice Akpinar
- London Centre for Nanotechnology, University College London, London, UK
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, London, UK
| | - Alice L B Pyne
- London Centre for Nanotechnology, University College London, London, UK.
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.
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6
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Bouzakher-Ghomrasni N, Taché O, Leroy J, Feltin N, Testard F, Chivas-Joly C. Dimensional measurement of TiO 2 (Nano) particles by SAXS and SEM in powder form. Talanta 2021; 234:122619. [PMID: 34364428 DOI: 10.1016/j.talanta.2021.122619] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 11/28/2022]
Abstract
The market for nano-additive materials has been growing exponentially since 2012, with almost 5040 consumer products containing nanoparticles in 2021. In parallel, the increasing recommendations, definitions and legislations underline the need for traceability of manufactured nanoparticles and for methods able to identify and quantify the "nano" dimensional character in manufactured product. From a multi-technic approach, this paper aims to compare the mesurands extracted from SAXS/BET (specific surface area) and SEM (diameter equivalent to a projected surface area) on different TiO2 powder issued from referenced, synthesized materials, raw materials (additives) and extracted materials from manufactured products. The influence of various parameters such as the anisotropic factor, the interaction between particles, the size distribution and the extraction steps are discussed to illustrate their impact on the diameter values issued from two different measurands. These results illustrate the difficulties in (nano)particles characterization. SEM and SAXS are complementary techniques depending on the level of dimensional characterization required.
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Affiliation(s)
- Najoua Bouzakher-Ghomrasni
- Laboratoire National de Métrologie et D'Essais, Nanometrology, CARMEN Platform, 29 Avenue Hennequin, 78197, Trappes Cedex, France
| | - Olivier Taché
- Université Paris-Saclay, CEA, CNRS, NIMBE, 91191, Gif-sur-Yvette, France
| | - Jocelyne Leroy
- Université Paris-Saclay, CEA, CNRS, NIMBE, 91191, Gif-sur-Yvette, France
| | - Nicolas Feltin
- Laboratoire National de Métrologie et D'Essais, Nanometrology, CARMEN Platform, 29 Avenue Hennequin, 78197, Trappes Cedex, France
| | - Fabienne Testard
- Université Paris-Saclay, CEA, CNRS, NIMBE, 91191, Gif-sur-Yvette, France.
| | - Carine Chivas-Joly
- Laboratoire National de Métrologie et D'Essais, Nanometrology, CARMEN Platform, 29 Avenue Hennequin, 78197, Trappes Cedex, France.
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7
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Strazdaite S, Roeters SJ, Sakalauskas A, Sneideris T, Kirschner J, Pedersen KB, Schiøtt B, Jensen F, Weidner T, Smirnovas V, Niaura G. Interaction of Amyloid-β-(1-42) Peptide and Its Aggregates with Lipid/Water Interfaces Probed by Vibrational Sum-Frequency Generation Spectroscopy. J Phys Chem B 2021; 125:11208-11218. [PMID: 34597059 DOI: 10.1021/acs.jpcb.1c04882] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we use surface-sensitive vibrational sum-frequency generation (VSFG) spectroscopy to investigate the interaction between model lipid monolayers and Aβ(1-42) in its monomeric and aggregated states. Combining VSFG with atomic force microscopy (AFM) and thioflavin T (ThT) fluorescence measurements, we found that only small aggregates with probably a β-hairpin-like structure adsorbed to the zwitterionic lipid monolayer (DOPC). In contrast, larger aggregates with an extended β-sheet structure adsorbed to a negatively charged lipid monolayer (DOPG). The adsorption of small, initially formed aggregates strongly destabilized both monolayers, but only the DOPC monolayer was completely disrupted. We showed that the intensity of the amide-II' band in achiral (SSP) and chiral (SPP) polarization combinations increased in time when Aβ(1-42) aggregates accumulated at the DOPG monolayer. Nevertheless, almost no adsorption of preformed mature fibrils to DOPG monolayers was detected. By performing spectral VSFG calculations, we revealed a clear correlation between the amide-II' signal and the degree of amyloid aggregates (e.g., oligomers or (proto)fibrils) of various Aβ(1-42) structures. The calculations showed that only structures with a significant amyloid β-sheet content have a strong amide-II' intensity, in line with previous Raman studies. The combination of the presented results substantiates the amide-II(') band as a legitimate amyloid marker.
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Affiliation(s)
- S Strazdaite
- Department of Organic Chemistry, Center for Physical Sciences and Technology, Sauletekio Ave. 3, Vilnius LT-10257, Lithuania
| | - S J Roeters
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - A Sakalauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - T Sneideris
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - J Kirschner
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - K B Pedersen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - B Schiøtt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - F Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - T Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - V Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, LT-10257 Vilnius, Lithuania
| | - G Niaura
- Department of Organic Chemistry, Center for Physical Sciences and Technology, Sauletekio Ave. 3, Vilnius LT-10257, Lithuania
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Konrad SF, Vanderlinden W, Lipfert J. A High-throughput Pipeline to Determine DNA and Nucleosome Conformations by AFM Imaging. Bio Protoc 2021; 11:e4180. [PMID: 34722827 DOI: 10.21769/bioprotoc.4180] [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: 04/28/2021] [Revised: 06/30/2021] [Accepted: 07/28/2021] [Indexed: 11/02/2022] Open
Abstract
Atomic force microscopy (AFM) is a powerful tool to image macromolecular complexes with nanometer resolution and exquisite single-molecule sensitivity. While AFM imaging is well-established to investigate DNA and nucleoprotein complexes, AFM studies are often limited by small datasets and manual image analysis that is slow and prone to user bias. Recently, we have shown that a combination of large scale AFM imaging and automated image analysis of nucleosomes can overcome these previous limitations of AFM nucleoprotein studies. Using our high-throughput imaging and analysis pipeline, we have resolved nucleosome wrapping intermediates with five base pair resolution and revealed how distinct nucleosome variants and environmental conditions affect the unwrapping pathways of nucleosomal DNA. Here, we provide a detailed protocol of our workflow to analyze DNA and nucleosome conformations focusing on practical aspects and experimental parameters. We expect our protocol to drastically enhance AFM analyses of DNA and nucleosomes and to be readily adaptable to a wide variety of other protein and protein-nucleic acid complexes.
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Affiliation(s)
- Sebastian F Konrad
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
| | - Willem Vanderlinden
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
| | - Jan Lipfert
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
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9
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Main KHS, Provan JI, Haynes PJ, Wells G, Hartley JA, Pyne ALB. Atomic force microscopy-A tool for structural and translational DNA research. APL Bioeng 2021; 5:031504. [PMID: 34286171 PMCID: PMC8272649 DOI: 10.1063/5.0054294] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/07/2021] [Indexed: 12/26/2022] Open
Abstract
Atomic force microscopy (AFM) is a powerful imaging technique that allows for structural characterization of single biomolecules with nanoscale resolution. AFM has a unique capability to image biological molecules in their native states under physiological conditions without the need for labeling or averaging. DNA has been extensively imaged with AFM from early single-molecule studies of conformational diversity in plasmids, to recent examinations of intramolecular variation between groove depths within an individual DNA molecule. The ability to image dynamic biological interactions in situ has also allowed for the interaction of various proteins and therapeutic ligands with DNA to be evaluated-providing insights into structural assembly, flexibility, and movement. This review provides an overview of how innovation and optimization in AFM imaging have advanced our understanding of DNA structure, mechanics, and interactions. These include studies of the secondary and tertiary structure of DNA, including how these are affected by its interactions with proteins. The broader role of AFM as a tool in translational cancer research is also explored through its use in imaging DNA with key chemotherapeutic ligands, including those currently employed in clinical practice.
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Affiliation(s)
| | - James I. Provan
- Institute of Molecular, Cell, and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | | | - Geoffrey Wells
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - John A. Hartley
- UCL Cancer Institute, University College London, London WC1E 6DD, United Kingdom
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10
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Nishide G, Lim K, Mohamed MS, Kobayashi A, Hazawa M, Watanabe-Nakayama T, Kodera N, Ando T, Wong RW. High-Speed Atomic Force Microscopy Reveals Spatiotemporal Dynamics of Histone Protein H2A Involution by DNA Inchworming. J Phys Chem Lett 2021; 12:3837-3846. [PMID: 33852305 DOI: 10.1021/acs.jpclett.1c00697] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
DNA-histone interaction is always perturbed by epigenetic regulators to regulate gene expression. Direct visualization of this interaction is yet to be achieved. By using high-speed atomic force microscopy (HS-AFM), we have observed the dynamic DNA-histone H2A interaction. HS-AFM movies demonstrate the globular core and disordered tail of H2A. DNA-H2A formed the classic "beads-on-string" conformation on poly-l-lysine (PLL) and lipid substrates. Notably, a short-linearized double-stranded DNA (dsDNA), resembling an inchworm, wrapped around a single H2A protein only observed on the lipid substrate. Such a phenomenon does not occur for plasmid DNA or linearized long dsDNA on the same substrate. Strong adsorption of PLL substrate resulted in poor dynamic DNA-H2A interaction. Nonetheless, short-linearized dsDNA-H2A formed stable wrapping with a "diamond ring" topology on the PLL substrate. Reversible liquid-liquid phase separation (LLPS) of the DNA-H2A aggregate was visualized by manipulating salt concentrations. Collectively, our study suggest that HS-AFM is feasible for investigating epigenetically modified DNA-histone interactions.
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Affiliation(s)
- Goro Nishide
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, WISE Program for Nano-Precision Medicine, Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Keesiang Lim
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Mahmoud Shaaban Mohamed
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Akiko Kobayashi
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Masaharu Hazawa
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | | | - Noriyuki Kodera
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Toshio Ando
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Richard W Wong
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, WISE Program for Nano-Precision Medicine, Science and Technology, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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11
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Konrad SF, Vanderlinden W, Frederickx W, Brouns T, Menze BH, De Feyter S, Lipfert J. High-throughput AFM analysis reveals unwrapping pathways of H3 and CENP-A nucleosomes. NANOSCALE 2021; 13:5435-5447. [PMID: 33683227 DOI: 10.1039/d0nr08564b] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nucleosomes, the fundamental units of chromatin, regulate readout and expression of eukaryotic genomes. Single-molecule experiments have revealed force-induced nucleosome accessibility, but a high-resolution unwrapping landscape in the absence of external forces is currently lacking. Here, we introduce a high-throughput pipeline for the analysis of nucleosome conformations based on atomic force microscopy and automated, multi-parameter image analysis. Our data set of ∼10 000 nucleosomes reveals multiple unwrapping states corresponding to steps of 5 bp DNA. For canonical H3 nucleosomes, we observe that dissociation from one side impedes unwrapping from the other side, but in contrast to force-induced unwrapping, we find only a weak sequence-dependent asymmetry. Notably, centromeric CENP-A nucleosomes do not unwrap anti-cooperatively, in stark contrast to H3 nucleosomes. Finally, our results reconcile previous conflicting findings about the differences in height between H3 and CENP-A nucleosomes. We expect our approach to enable critical insights into epigenetic regulation of nucleosome structure and stability and to facilitate future high-throughput AFM studies that involve heterogeneous nucleoprotein complexes.
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Affiliation(s)
- Sebastian F Konrad
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
| | - Willem Vanderlinden
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
| | - Wout Frederickx
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Tine Brouns
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Björn H Menze
- Department of Informatics, Technical University of Munich, Boltzmannstr. 3, 85748 Garching, Germany
| | - Steven De Feyter
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Jan Lipfert
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
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12
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Franquelim HG, Dietz H, Schwille P. Reversible membrane deformations by straight DNA origami filaments. SOFT MATTER 2021; 17:276-287. [PMID: 32406895 DOI: 10.1039/d0sm00150c] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Membrane-active cytoskeletal elements, such as FtsZ, septin or actin, form filamentous polymers able to induce and stabilize curvature on cellular membranes. In order to emulate the characteristic dynamic self-assembly properties of cytoskeletal subunits in vitro, biomimetic synthetic scaffolds were here developed using DNA origami. In contrast to our earlier work with pre-curved scaffolds, we specifically assessed the potential of origami mimicking straight filaments, such as actin and microtubules, by origami presenting cholesteryl anchors for membrane binding and additional blunt end stacking interactions for controllable polymerization into linear filaments. By assessing the interaction of our DNA nanostructures with model membranes using fluorescence microscopy, we show that filaments can be formed, upon increasing MgCl2 in solution, for structures displaying blunt ends; and can subsequently depolymerize, by decreasing the concentration of MgCl2. Distinctive spike-like membrane protrusions were generated on giant unilamellar vesicles at high membrane-bound filament densities, and the presence of such deformations was reversible and shown to correlate with the MgCl2-triggered polymerization of DNA origami subunits into filamentous aggregates. In the end, our approach reveals the formation of membrane-bound filaments as a minimal requirement for membrane shaping by straight cytoskeletal-like objects.
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Affiliation(s)
| | - Hendrik Dietz
- Technical University of Munich, Garching Near Munich, Germany
| | - Petra Schwille
- Max Planck Institute of Biochemistry, Martinsried near Munich, Germany.
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13
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Akpinar B, Haynes PJ, Bell NAW, Brunner K, Pyne ALB, Hoogenboom BW. PEGylated surfaces for the study of DNA-protein interactions by atomic force microscopy. NANOSCALE 2019; 11:20072-20080. [PMID: 31612171 PMCID: PMC6964798 DOI: 10.1039/c9nr07104k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 09/22/2019] [Indexed: 05/20/2023]
Abstract
DNA-protein interactions are vital to cellular function, with key roles in the regulation of gene expression and genome maintenance. Atomic force microscopy (AFM) offers the ability to visualize DNA-protein interactions at nanometre resolution in near-physiological buffers, but it requires that the DNA be adhered to the surface of a solid substrate. This presents a problem when working in biologically relevant protein concentrations, where proteins may be present in large excess in solution; much of the biophysically relevant information can therefore be occluded by non-specific protein binding to the underlying substrate. Here we explore the use of PLLx-b-PEGy block copolymers to achieve selective adsorption of DNA on a mica surface for AFM studies. Through varying both the number of lysine and ethylene glycol residues in the block copolymers, we show selective adsorption of DNA on mica that is functionalized with a PLL10-b-PEG113/PLL1000-2000 mixture as viewed by AFM imaging in a solution containing high concentrations of streptavidin. We show - through the use of biotinylated DNA and streptavidin - that this selective adsorption extends to DNA-protein complexes and that DNA-bound streptavidin can be unambiguously distinguished in spite of an excess of unbound streptavidin in solution. Finally, we apply this to the nuclear enzyme PARP1, resolving the binding of individual PARP1 molecules to DNA by in-liquid AFM.
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Affiliation(s)
- Bernice Akpinar
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK. and Department of Chemistry, Imperial College London, SW7 2AZ, UK
| | - Philip J Haynes
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK. and Department of Chemistry, Imperial College London, SW7 2AZ, UK
| | | | - Katharina Brunner
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK and Discovery Biology, Discovery Sciences, R&D, AstraZeneca, 50F49, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK
| | - Alice L B Pyne
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK. and Department of Materials Science and Engineering, University of Sheffield, S1 3JD, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK. and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
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14
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Würtz M, Aumiller D, Gundelwein L, Jung P, Schütz C, Lehmann K, Tóth K, Rohr K. DNA accessibility of chromatosomes quantified by automated image analysis of AFM data. Sci Rep 2019; 9:12788. [PMID: 31484969 PMCID: PMC6726762 DOI: 10.1038/s41598-019-49163-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/19/2019] [Indexed: 12/26/2022] Open
Abstract
DNA compaction and accessibility in eukaryotes are governed by nucleosomes and orchestrated through interactions between DNA and DNA-binding proteins. Using QuantAFM, a method for automated image analysis of atomic force microscopy (AFM) data, we performed a detailed statistical analysis of structural properties of mono-nucleosomes. QuantAFM allows fast analysis of AFM images, including image preprocessing, object segmentation, and quantification of different structural parameters to assess DNA accessibility of nucleosomes. A comparison of nucleosomes reconstituted with and without linker histone H1 quantified H1's already described ability of compacting the nucleosome. We further employed nucleosomes bearing two charge-modifying mutations at position R81 and R88 in histone H2A (H2A R81E/R88E) to characterize DNA accessibility under destabilizing conditions. Upon H2A mutation, even in presence of H1, the DNA opening angle at the entry/exit site was increased and the DNA wrapping length around the histone core was reduced. Interestingly, a distinct opening of the less bendable DNA side was observed upon H2A mutation, indicating an enhancement of the intrinsic asymmetry of the Widom-601 nucleosomes. This study validates AFM as a technique to investigate structural parameters of nucleosomes and highlights how the DNA sequence, together with nucleosome modifications, can influence the DNA accessibility.
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Affiliation(s)
- Martin Würtz
- German Cancer Research Center, Division Biophysics of Macromolecules, Heidelberg, 69120, Germany
- Heidelberg University, BioQuant and IPMB, Biomedical Computer Vision Group, Heidelberg, 69120, Germany
| | - Dennis Aumiller
- Heidelberg University, Institute of Computer Science, Heidelberg, 69120, Germany
| | - Lina Gundelwein
- Heidelberg University, Institute of Computer Science, Heidelberg, 69120, Germany
| | - Philipp Jung
- Heidelberg University, Institute of Computer Science, Heidelberg, 69120, Germany
| | - Christian Schütz
- Heidelberg University, Institute of Computer Science, Heidelberg, 69120, Germany
| | - Kathrin Lehmann
- German Cancer Research Center, Division Biophysics of Macromolecules, Heidelberg, 69120, Germany
- Simon Fraser University, Department of Physics, Burnaby, BC, V5A 1S6, Canada
| | - Katalin Tóth
- German Cancer Research Center, Division Biophysics of Macromolecules, Heidelberg, 69120, Germany
| | - Karl Rohr
- Heidelberg University, BioQuant and IPMB, Biomedical Computer Vision Group, Heidelberg, 69120, Germany.
- German Cancer Research Center, Heidelberg, 69120, Germany.
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15
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Brouns T, De Keersmaecker H, Konrad SF, Kodera N, Ando T, Lipfert J, De Feyter S, Vanderlinden W. Free Energy Landscape and Dynamics of Supercoiled DNA by High-Speed Atomic Force Microscopy. ACS NANO 2018; 12:11907-11916. [PMID: 30346700 DOI: 10.1021/acsnano.8b06994] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
DNA supercoiling fundamentally constrains and regulates the storage and use of genetic information. While the equilibrium properties of supercoiled DNA are relatively well understood, the dynamics of supercoils are much harder to probe. Here we use atomic force microscopy (AFM) imaging to demonstrate that positively supercoiled DNA plasmids, in contrast to their negatively supercoiled counterparts, preserve their plectonemic geometry upon adsorption under conditions that allow for dynamics and equilibration on the surface. Our results are in quantitative agreement with a physical polymer model for supercoiled plasmids that takes into account the known mechanical properties and torque-induced melting of DNA. We directly probe supercoil dynamics using high-speed AFM imaging with subsecond time and ∼nanometer spatial resolution. From our recordings we quantify self-diffusion, branch point flexibility, and slithering dynamics and demonstrate that reconfiguration of molecular extensions is predominantly governed by the bending flexibility of plectoneme arms. We expect that our methodology can be an asset to probe protein-DNA interactions and topochemical reactions on physiological relevant DNA length and supercoiling scales by high-resolution AFM imaging.
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Affiliation(s)
- Tine Brouns
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Herlinde De Keersmaecker
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Sebastian F Konrad
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
| | - Noriyuki Kodera
- Nano-Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi , Kanazawa , 920-1192 , Japan
| | - Toshio Ando
- Nano-Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kakuma-machi , Kanazawa , 920-1192 , Japan
| | - Jan Lipfert
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
| | - Steven De Feyter
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
| | - Willem Vanderlinden
- KU Leuven, Division of Molecular Imaging and Photonics , Celestijnenlaan 200F , 3001 Leuven , Belgium
- Department of Physics , Nanosystems Initiative Munich, and Center for NanoScience , LMU Munich, Amalienstrasse 54 , 80799 Munich , Germany
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16
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Ghilini F, Rodríguez González MC, Miñán AG, Pissinis D, Creus AH, Salvarezza RC, Schilardi PL. Highly Stabilized Nanoparticles on Poly-l-Lysine-Coated Oxidized Metals: A Versatile Platform with Enhanced Antimicrobial Activity. ACS APPLIED MATERIALS & INTERFACES 2018; 10:23657-23666. [PMID: 29927235 DOI: 10.1021/acsami.8b07529] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The increasing incidence of infections in implantable devices has encouraged the search for biocompatible antimicrobial surfaces. To inhibit the bacterial adhesion and proliferation on biomaterials, several surface functionalization strategies have been developed. However, most of these strategies lead to bacteriostatic effect and only few of these are able to reach the bactericidal condition. In this work, bactericidal surfaces were designed through the functionalization of titanium surfaces with poly-l-lysine (PLL) as the mediator for the incorporation of antimicrobial silver nanoparticles (AgNPs). This functionalization influences the adsorption of the particles on the substrate impeding the agglomeration observed when bare titanium surfaces are used, leading to a homogeneous distribution of AgNPs on the surfaces. The antimicrobial activity of this surface has been tested against two different strains, namely, Staphylococcus aureus and Pseudomonas aeruginosa. For both strains and different AgNPs sizes, the surface modified with PLL and AgNPs shows a much enhanced antimicrobial activity in comparison with AgNPs deposited on bare titanium. This enhanced antibacterial activity is high enough to reach bactericidal effect, a condition hard to achieve in antimicrobial surfaces. Importantly, the designed surfaces are able to decrease the bacterial viability more than 5 orders with respect to the initial bacterial inoculum. That means that a relative low load of AgNPs on the PLL-modified titanium surfaces reaches 99.999% bacterial death after 24 h. The results of the present study are important to avoid infections in indwelling materials by reinforcing the preventive antibiotic therapy usually dosed throughout the surgical procedure and during the postoperative period.
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Affiliation(s)
- Fiorela Ghilini
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP-CONICET, CC16 Suc4 , La Plata 1900 , Buenos Aires , Argentina
| | - Miriam C Rodríguez González
- Área de Química Física, Departamento de Química, Facultad de Ciencias , Universidad de La Laguna, Instituto de Materiales y Nanotecnología (IMN) , 38200 La Laguna , Tenerife , Spain
| | - Alejandro G Miñán
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP-CONICET, CC16 Suc4 , La Plata 1900 , Buenos Aires , Argentina
| | - Diego Pissinis
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP-CONICET, CC16 Suc4 , La Plata 1900 , Buenos Aires , Argentina
| | - Alberto Hernández Creus
- Área de Química Física, Departamento de Química, Facultad de Ciencias , Universidad de La Laguna, Instituto de Materiales y Nanotecnología (IMN) , 38200 La Laguna , Tenerife , Spain
| | - Roberto C Salvarezza
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP-CONICET, CC16 Suc4 , La Plata 1900 , Buenos Aires , Argentina
| | - Patricia L Schilardi
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP-CONICET, CC16 Suc4 , La Plata 1900 , Buenos Aires , Argentina
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17
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Frederickx W, Rocha S, Fujita Y, Kennes K, De Keersmaecker H, De Feyter S, Uji-I H, Vanderlinden W. Orthogonal Probing of Single-Molecule Heterogeneity by Correlative Fluorescence and Force Microscopy. ACS NANO 2018; 12:168-177. [PMID: 29257876 DOI: 10.1021/acsnano.7b05405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Correlative imaging by fluorescence and force microscopy is an emerging technology to acquire orthogonal information at the nanoscale. Whereas atomic force microscopy excels at resolving the envelope structure of nanoscale specimens, fluorescence microscopy can detect specific molecular labels, which enables the unambiguous recognition of molecules in a complex assembly. Whereas correlative imaging at the micrometer scale has been established, it remains challenging to push the technology to the single-molecule level. Here, we used an integrated setup to systematically evaluate the factors that influence the quality of correlative fluorescence and force microscopy. Optimized data processing to ensure accurate drift correction and high localization precision results in image registration accuracies of ∼25 nm on organic fluorophores, which represents a 2-fold improvement over the state of the art in correlative fluorescence and force microscopy. Furthermore, we could extend the Atto532 fluorophore bleaching time ∼2-fold, by chemical modification of the supporting mica surface. In turn, this enables probing the composition of macromolecular complexes by stepwise photobleaching with high confidence. We demonstrate the performance of our method by resolving the stoichiometry of molecular subpopulations in a heterogeneous EcoRV-DNA nucleoprotein ensemble.
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Affiliation(s)
- Wout Frederickx
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Susana Rocha
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Yasuhiko Fujita
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Koen Kennes
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Herlinde De Keersmaecker
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Steven De Feyter
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Hiroshi Uji-I
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
- Research Institute for Electronic Science, Nanomaterials and Nanoscopy, Hokkaido University , Kita 10 Nishi 20, North Ward, Sapporo 001-0020, Japan
| | - Willem Vanderlinden
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
- Department of Physics, Nanosystems Initiative Munich, and Center for NanoScience, LMU Munich , Amalienstrasse 54, 80799 Munich, Germany
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18
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Meroni A, Lazzaro F, Muzi-Falconi M, Podestà A. Characterization of Structural and Configurational Properties of DNA by Atomic Force Microscopy. Methods Mol Biol 2018; 1672:557-573. [PMID: 29043648 DOI: 10.1007/978-1-4939-7306-4_37] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We describe a method to extract quantitative information on DNA structural and configurational properties from high-resolution topographic maps recorded by atomic force microscopy (AFM). DNA molecules are deposited on mica surfaces from an aqueous solution, carefully dehydrated, and imaged in air in Tapping Mode. Upon extraction of the spatial coordinates of the DNA backbones from AFM images, several parameters characterizing DNA structure and configuration can be calculated. Here, we explain how to obtain the distribution of contour lengths, end-to-end distances, and gyration radii. This modular protocol can be also used to characterize other statistical parameters from AFM topographies.
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Affiliation(s)
- Alice Meroni
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133, Milano, Italy
| | - Federico Lazzaro
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133, Milano, Italy
| | - Marco Muzi-Falconi
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133, Milano, Italy
| | - Alessandro Podestà
- Dipartimento di Fisica and C.I.Ma.I.Na, Università degli Studi di Milano, via Celoria 16, 20133, Milano, Italy.
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19
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Lehmann K, Zhang R, Schwarz N, Gansen A, Mücke N, Langowski J, Toth K. Effects of charge-modifying mutations in histone H2A α3-domain on nucleosome stability assessed by single-pair FRET and MD simulations. Sci Rep 2017; 7:13303. [PMID: 29038501 PMCID: PMC5643395 DOI: 10.1038/s41598-017-13416-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/21/2017] [Indexed: 01/01/2023] Open
Abstract
Nucleosomes are important for chromatin compaction and gene regulation; their integrity depends crucially on the structural properties of the histone tails. Recent all-atom molecular dynamics simulations revealed that removal of the N-terminal tails of histone H3, known to destabilize nucleosomes, causes a rearrangement of two arginines of histone H2A, namely R81 and R88 by altering the electrostatic environment of the H2A α3 domain. Whether this rearrangement is the cause or the effect of decreased stability, is unclear. Here, we emulate the altered electrostatic environment that was found after H3 tail clipping through charge-modifying mutations to decouple its impact on intranucleosomal interactions from that of the histone tails. Förster resonance energy transfer experiments on recombinant nucleosomes and all-atom molecular dynamics simulations reveal a compensatory role of those amino acids in nucleosome stability. The simulations indicate a weakened interface between H2A-H2B dimers and the (H3-H4)2 tetramer, as well as between dimers and DNA. These findings agree with the experimental observations of position and charge dependent decreased nucleosome stability induced by the introduced mutations. This work highlights the importance of the H2A α3 domain and suggests allosteric effects between this domain and the outer DNA gyre as well as the H3 N-terminal tail.
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Affiliation(s)
- Kathrin Lehmann
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany.
| | - Ruihan Zhang
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany.,Key laboratory of medicinal chemistry for natural resources, Ministry of Education, Yunnan University, Kunming, Yunnan, 650091, China
| | - Nathalie Schwarz
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Alexander Gansen
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Norbert Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Katalin Toth
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, D-69120, Germany.
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20
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Krzemien KM, Beckers M, Quack S, Michaelis J. Atomic force microscopy of chromatin arrays reveal non-monotonic salt dependence of array compaction in solution. PLoS One 2017; 12:e0173459. [PMID: 28296908 PMCID: PMC5351988 DOI: 10.1371/journal.pone.0173459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/22/2017] [Indexed: 12/03/2022] Open
Abstract
Compaction of DNA in chromatin is a hallmark of the eukaryotic cell and unravelling its structure is required for an understanding of DNA involving processes. Despite strong experimental efforts, many questions concerning the DNA packing are open. In particular, it is heavily debated whether an ordered structure referred to as the “30 nm fibre” exist in vivo. Scanning probe microscopy has become a cutting edge technology for the high-resolution imaging of DNA- protein complexes. Here, we perform high-resolution atomic force microscopy of non-cross-linked chromatin arrays in liquid, under different salt conditions. A statistical analysis of the data reveals that array compaction is salt dependent in a non-monotonic fashion. A simple physical model can qualitatively explain the observed findings due to the opposing effects of salt dependent stiffening of DNA, nucleosome stability and histone-histone interactions. While for different salt concentrations different compaction states are observed, our data do not provide support for the existence of regular chromatin fibres. Our studies add new insights into chromatin structure, and with that contribute to a further understanding of the DNA condensation.
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Affiliation(s)
| | | | - Salina Quack
- Institute of Biophysics, Ulm University, Ulm, Germany
| | - Jens Michaelis
- Institute of Biophysics, Ulm University, Ulm, Germany
- * E-mail:
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21
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Bagrov D, Gazizova Y, Podgorsky V, Udovichenko I, Danilkovich A, Prusakov K, Klinov D. Morphology and aggregation of RADA-16-I peptide Studied by AFM, NMR and molecular dynamics simulations. Biopolymers 2017; 106:72-81. [PMID: 26501800 DOI: 10.1002/bip.22755] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 08/31/2015] [Accepted: 10/17/2015] [Indexed: 01/25/2023]
Abstract
RADA-16-I is a self-assembling peptide which forms biocompatible fibrils and hydrogels. We used molecular dynamics simulations, atomic-force microscopy, NMR spectroscopy, and thioflavin T binding assay to examine size, structure, and morphology of RADA-16-I aggregates. We used the native form of RADA-16-I (H-(ArgAlaAspAla)4 -OH) rather than the acetylated one commonly used in the previous studies. At neutral pH, RADA-16-I is mainly in the fibrillar form, the fibrils consist of an even number of stacked β-sheets. At acidic pH, RADA-16-I fibrils disassemble into monomers, which form an amorphous monolayer on graphite and monolayer lamellae on mica. RADA-16-I fibrils were compared with the fibrils of a similar peptide RLDL-16-I. Thickness of β-sheets measured by AFM was in excellent agreement with the molecular dynamics simulations. A pair of RLDL-16-I β-sheets was thicker (2.3 ± 0.4 nm) than a pair of RADA-16-I β-sheets (1.9 ± 0.1 nm) due to the volume difference between alanine and leucine residues.
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Affiliation(s)
- Dmitry Bagrov
- Scientific Research Institute of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a Moscow, 119435, Russian Federation.,Faculty of Biology, Department of Bioengineering, M.V. Lomonosov Moscow State University, Leninskie Gory, 1/73, Moscow, 111991, Russian Federation
| | - Yuliya Gazizova
- Scientific Research Institute of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a Moscow, 119435, Russian Federation.,Department of Biological and Medical Physics, Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region, 141700, Russian Federation
| | - Victor Podgorsky
- Scientific Research Institute of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a Moscow, 119435, Russian Federation
| | - Igor Udovichenko
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Prospect Nauki-6, Pushchino, 142290, Russian Federation.,Pushchino State Institute of Natural Science, Prospect Nauki-3, Pushchino, 142290, Russian Federation
| | - Alexey Danilkovich
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Prospect Nauki-6, Pushchino, 142290, Russian Federation.,Pushchino State Institute of Natural Science, Prospect Nauki-3, Pushchino, 142290, Russian Federation
| | - Kirill Prusakov
- Scientific Research Institute of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a Moscow, 119435, Russian Federation
| | - Dmitry Klinov
- Scientific Research Institute of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a Moscow, 119435, Russian Federation.,Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, 16/10, Moscow, 117997, Russian Federation
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22
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Noy A, Sutthibutpong T, A Harris S. Protein/DNA interactions in complex DNA topologies: expect the unexpected. Biophys Rev 2016; 8:145-155. [PMID: 28035245 PMCID: PMC5153831 DOI: 10.1007/s12551-016-0241-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/13/2016] [Indexed: 01/09/2023] Open
Abstract
DNA supercoiling results in compacted DNA structures that can bring distal sites into close proximity. It also changes the local structure of the DNA, which can in turn influence the way it is recognised by drugs, other nucleic acids and proteins. Here, we discuss how DNA supercoiling and the formation of complex DNA topologies can affect the thermodynamics of DNA recognition. We then speculate on the implications for transcriptional control and the three-dimensional organisation of the genetic material, using examples from our own simulations and from the literature. We introduce and discuss the concept of coupling between the multiple length-scales associated with hierarchical nuclear structural organisation through DNA supercoiling and topology.
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Affiliation(s)
- Agnes Noy
- Department of Physics, Biological Physical Sciences Institute, University of York, York, YO10 5DD UK
| | - Thana Sutthibutpong
- Theoretical and Computational Physics Group, Department of Physics, King Mongkut University of Technology Thonburi, 126 Pracha Uthit Road, Bang Mod, Thung Khru, Bangkok, Thailand 10140
| | - Sarah A Harris
- School of Physics and Astronomy, University of Leeds, 192 Woodhouse Lane, Leeds, UK LS2 9JT ; Astbury Centre for Structural and Molecular Biology, University of Leeds, 192 Woodhouse Lane, Leeds, UK LS2 9JT
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23
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Noy A, Sutthibutpong T, A Harris S. Protein/DNA interactions in complex DNA topologies: expect the unexpected. Biophys Rev 2016; 8:233-243. [PMID: 27738452 PMCID: PMC5039213 DOI: 10.1007/s12551-016-0208-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/13/2016] [Indexed: 12/31/2022] Open
Abstract
DNA supercoiling results in compacted DNA structures that can bring distal sites into close proximity. It also changes the local structure of the DNA, which can in turn influence the way it is recognised by drugs, other nucleic acids and proteins. Here, we discuss how DNA supercoiling and the formation of complex DNA topologies can affect the thermodynamics of DNA recognition. We then speculate on the implications for transcriptional control and the three-dimensional organisation of the genetic material, using examples from our own simulations and from the literature. We introduce and discuss the concept of coupling between the multiple length-scales associated with hierarchical nuclear structural organisation through DNA supercoiling and topology.
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Affiliation(s)
- Agnes Noy
- Department of Physics, Biological Physical Sciences Institute, University of York, York, YO10 5DD UK
| | - Thana Sutthibutpong
- Theoretical and Computational Physics Group, Department of Physics, King Mongkut University of Technology Thonburi, 126 Pracha Uthit Road, Bang Mod, Thung Khru, Bangkok, Thailand 10140
| | - Sarah A Harris
- School of Physics and Astronomy, University of Leeds, 192 Woodhouse Lane, Leeds, UK LS2 9JT ; Astbury Centre for Structural and Molecular Biology, University of Leeds, 192 Woodhouse Lane, Leeds, UK LS2 9JT
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24
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Burns JR, Seifert A, Fertig N, Howorka S. A biomimetic DNA-based channel for the ligand-controlled transport of charged molecular cargo across a biological membrane. NATURE NANOTECHNOLOGY 2016; 11:152-6. [PMID: 26751170 DOI: 10.1038/nnano.2015.279] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 10/29/2015] [Indexed: 05/21/2023]
Abstract
Biological ion channels are molecular gatekeepers that control transport across cell membranes. Recreating the functional principle of such systems and extending it beyond physiological ionic cargo is both scientifically exciting and technologically relevant to sensing or drug release. However, fabricating synthetic channels with a predictable structure remains a significant challenge. Here, we use DNA as a building material to create an atomistically determined molecular valve that can control when and which cargo is transported across a bilayer. The valve, which is made from seven concatenated DNA strands, can bind a specific ligand and, in response, undergo a nanomechanical change to open up the membrane-spanning channel. It is also able to distinguish with high selectivity the transport of small organic molecules that differ by the presence of a positively or negatively charged group. The DNA device could be used for controlled drug release and the building of synthetic cell-like or logic ionic networks.
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Affiliation(s)
- Jonathan R Burns
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK
| | | | | | - Stefan Howorka
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK
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25
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Japaridze A, Vobornik D, Lipiec E, Cerreta A, Szczerbinski J, Zenobi R, Dietler G. Toward an Effective Control of DNA’s Submolecular Conformation on a Surface. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b01827] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Aleksandre Japaridze
- Laboratory
of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Dusan Vobornik
- Laboratory
of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Ewelina Lipiec
- The
Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, Poland
| | - Andrea Cerreta
- Laboratory
of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Jacek Szczerbinski
- Laboratory
of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Renato Zenobi
- Laboratory
of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Giovanni Dietler
- Laboratory
of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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26
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Abstract
Atomic force microscopy (AFM) is a microscopy technique that uses a sharp probe to trace a sample surface at nanometre resolution. For biological applications, one of its key advantages is its ability to visualize substructure of single molecules and molecular complexes in an aqueous environment. Here, we describe the application of AFM to determine superstructure and secondary structure of surface-bound DNA. The method is also readily applicable to probe DNA-DNA interactions and DNA-protein complexes.
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Affiliation(s)
- Alice L B Pyne
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK.
| | - Bart W Hoogenboom
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK.
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27
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Abstract
This article reviews atomic force microscopy (AFM) studies of DNA structure and dynamics and protein-DNA complexes, including recent advances in the visualization of protein-DNA complexes with the use of cutting-edge, high-speed AFM. Special emphasis is given to direct nanoscale visualization of dynamics of protein-DNA complexes. In the area of DNA structure and dynamics, structural studies of local non-B conformations of DNA and the interplay of local and global DNA conformations are reviewed. The application of time-lapse AFM nanoscale imaging of DNA dynamics is illustrated by studies of Holliday junction branch migration. Structure and dynamics of protein-DNA interactions include problems related to site-specific DNA recombination, DNA replication, and DNA mismatch repair. Studies involving the structure and dynamics of chromatin are also described.
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Affiliation(s)
- Yuri L. Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025
| | - Luda S. Shlyakhtenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025
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28
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Elbel T, Langowski J. The effect of DNA supercoiling on nucleosome structure and stability. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:064105. [PMID: 25563201 DOI: 10.1088/0953-8984/27/6/064105] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nucleosomes have to open to allow access to DNA in transcription, replication, and DNA damage repair. Changes in DNA torsional strain (e.g. during transcription elongation) influence the accessibility of nucleosomal DNA. Here we investigated the effect of DNA supercoiling-induced torsional strain on nucleosome structure and stability by scanning force microscopy (SFM) and fluorescence correlation spectroscopy (FCS). Nucleosomes were reconstituted onto 2.7 kb DNA plasmids with varying superhelical densities. The SFM results show a clear dependence of the amount of DNA wrapped around the nucleosome core on the strength and type of supercoiling. Negative supercoiling led to smaller nucleosome opening angles as compared to relaxed or positively supercoiled DNA. FCS experiments show that nucleosomes reconstituted on negatively superhelical DNA are more resistant to salt-induced destabilization, as seen by reduced H2A-H2B dimer eviction from the nucleosome. Our results show that changes in DNA topology, e.g. during transcription elongation, affect the accessibility of nucleosomal DNA.
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Affiliation(s)
- Tabea Elbel
- German Cancer Research Center (DKFZ), Biophysics of Macromolecules (B040), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany
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29
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Berg F, Wilken J, Helm CA, Block S. AFM-Based Quantification of Conformational Changes in DNA Caused by Reactive Oxygen Species. J Phys Chem B 2014; 119:25-32. [DOI: 10.1021/jp507659x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Florian Berg
- Institut
für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Strasse 6, D-17487 Greifswald, Germany
| | - Janine Wilken
- Institut
für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Strasse 6, D-17487 Greifswald, Germany
| | - Christiane A. Helm
- Institut
für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Strasse 6, D-17487 Greifswald, Germany
| | - Stephan Block
- Institut
für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Strasse 6, D-17487 Greifswald, Germany
- Department
of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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30
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Schmatko T, Muller P, Maaloum M. Surface charge effects on the 2D conformation of supercoiled DNA. SOFT MATTER 2014; 10:2520-2529. [PMID: 24647451 DOI: 10.1039/c3sm53071j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have adsorbed plasmid pUc19 DNA on a supported bilayer. By varying the fraction of cationic lipids in the membrane, we have tuned the surface charge. Plasmid conformations were imaged by Atomic Force Microscopy (AFM). We performed two sets of experiments: deposition from salt free solution on charged bilayers and deposition from salty solutions on neutral bilayers. Both sets show similar trends: at low surface charge density or low bulk salt concentration, the internal electrostatic repulsion forces plasmids to adopt completely opened structures, while at high surface charge density or higher bulk salt concentration, usual supercoiled plectonemes are observed. We experimentally demonstrate the equivalence of surface screening by mobile interfacial charges and bulk screening from salt ions. At low to medium screening, the electrostatic repulsion at plasmid crossings is predominant, leading to a number of crossovers decreasing linearly with the characteristic screening length. We compare our data with an analytical 2D-equilibrated model developed recently for the system and extract the DNA effective charge density when strands are adsorbed at the surface.
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Affiliation(s)
- Tatiana Schmatko
- Institut Charles Sadron, CNRS UPR 22 et Université de Strasbourg, 23 rue du loess, BP 84047 67034 Strasbourg Cedex2, France.
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31
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Hernandez-Garcia A, Werten MWT, Stuart MC, de Wolf FA, de Vries R. Coating of single DNA molecules by genetically engineered protein diblock copolymers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3491-3501. [PMID: 22865731 DOI: 10.1002/smll.201200939] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Indexed: 06/01/2023]
Abstract
Coating DNA is an effective way to modulate its physical properties and interactions. Current chemosynthetic polymers form DNA aggregates with random size and shape. In this study, monodisperse protein diblock copolymers are produced at high yield in recombinant yeast. They carry a large hydrophilic colloidal block (≈400 amino acids) linked to a short binding block (≈12 basic amino acids). It is demonstrated that these protein polymers complex single DNA molecules as highly stable nanorods, reminiscent of cylindrical viruses. It is proposed that inter- and intramolecular bridging of DNA molecules are prevented completely by the small size of the binding block attached to the large colloidal stability block. These protein diblocks serve as a scaffold that can be tuned for application in DNA-based nanotechnology.
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Affiliation(s)
- Armando Hernandez-Garcia
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands; Dutch Polymer Institute, John F. Kennedylaan 2, 5612 AB Eindhoven, The Netherlands.
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32
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Iacomino G, Picariello G, Sbrana F, Di Luccia A, Raiteri R, D’Agostino L. DNA is Wrapped by the Nuclear Aggregates of Polyamines: The Imaging Evidence. Biomacromolecules 2011; 12:1178-86. [DOI: 10.1021/bm101478j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Giuseppe Iacomino
- Istituto di Scienze dell’Alimentazione, CNR, via Roma 64, 83100 Avellino, Italy
| | - Gianluca Picariello
- Istituto di Scienze dell’Alimentazione, CNR, via Roma 64, 83100 Avellino, Italy
| | - Francesca Sbrana
- Dipartimento di Ingegneria Biofisica ed Elettronica, Università degli Studi di Genova, via all'Opera Pia 11a, 16145 Genova, Italy
| | - Aldo Di Luccia
- Istituto di Scienze dell’Alimentazione, CNR, via Roma 64, 83100 Avellino, Italy
- Dipartimento di Scienze degli Alimenti, Università degli Studi di Foggia, via Napoli 25, 71122 Foggia, Italy
| | - Roberto Raiteri
- Dipartimento di Ingegneria Biofisica ed Elettronica, Università degli Studi di Genova, via all'Opera Pia 11a, 16145 Genova, Italy
| | - Luciano D’Agostino
- Istituto di Scienze dell’Alimentazione, CNR, via Roma 64, 83100 Avellino, Italy
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33
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Wu M, Zampini M, Bussiek M, Hoischen C, Diekmann S, Hayes F. Segrosome assembly at the pliable parH centromere. Nucleic Acids Res 2011; 39:5082-97. [PMID: 21378121 PMCID: PMC3130281 DOI: 10.1093/nar/gkr115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The segrosome of multiresistance plasmid TP228 comprises ParF, which is a member of the ParA ATPase superfamily, and the ParG ribbon–helix–helix factor that assemble jointly on the parH centromere. Here we demonstrate that the distinctive parH site (∼100-bp) consists of an array of degenerate tetramer boxes interspersed by AT-rich spacers. Although numerous consecutive AT-steps are suggestive of inherent curvature, parH lacks an intrinsic bend. Sequential deletion of parH tetramers progressively reduced centromere function. Nevertheless, the variant subsites could be rearranged in different geometries that accommodated centromere activity effectively revealing that the site is highly elastic in vivo. ParG cooperatively coated parH: proper centromere binding necessitated the protein's N-terminal flexible tails which modulate the centromere binding affinity of ParG. Interaction of the ParG ribbon–helix–helix domain with major groove bases in the tetramer boxes likely provides direct readout of the centromere. In contrast, the AT-rich spacers may be implicated in indirect readout that mediates cooperativity between ParG dimers assembled on adjacent boxes. ParF alone does not bind parH but instead loads into the segrosome interactively with ParG, thereby subtly altering centromere conformation. Assembly of ParF into the complex requires the N-terminal flexible tails in ParG that are contacted by ParF.
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Affiliation(s)
- Meiyi Wu
- Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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34
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Rivetti C. DNA contour length measurements as a tool for the structural analysis of DNA and nucleoprotein complexes. Methods Mol Biol 2011; 749:235-254. [PMID: 21674377 DOI: 10.1007/978-1-61779-142-0_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The atomic force microscope (AFM) is a widely used tool to image DNA and nucleoprotein complexes at the molecular level. This is because the AFM is relatively easy to operate, has the capability to image biomolecules under aqueous solutions, and, most importantly, can image mesoscopic macromolecular structures that are too complex to be studied by X-ray or NMR and too small to be visualized with the optical microscope. Although there are many AFM studies about the structure and the physical properties of DNA, only in few cases a rigorous method has been applied to analyze AFM images. This chapter describes procedures to prepare DNA and nucleoprotein complexes for AFM imaging and methods used to carry out simple image measurements to obtain structural data. In particular, methods to measure DNA contour length and the volume of free or DNA-bound proteins are presented and discussed.
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Affiliation(s)
- Claudio Rivetti
- Department of Biochemistry and Molecular Biology, University of Parma, Parma, Italy.
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35
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Xiao Z, Cao L, Zhu D, Lu Z. Atomic force microscopy studies on circular DNA structural changes by vincristine and aspirin. Methods Mol Biol 2011; 736:425-435. [PMID: 21660742 DOI: 10.1007/978-1-61779-105-5_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this chapter, we have presented materials and methods to study the interaction between DNA and small molecule drugs by AFM. The detailed AFM imaging of the circular DNA after incubation with -various concentrations of vincristine and aspirin have been demonstrated. The immobilization of DNA fragments on mica surface as well as the force between tip and sample plays an important role for successful imaging of DNA-drug complexes. How to quantitatively describe the conformations and structures of circular DNA molecules and their changes is also introduced. Our work indicates that the AFM is a powerful tool in studying the interaction between DNA and small molecules.
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Affiliation(s)
- Zhongdang Xiao
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China.
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36
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Jiang Y, Rabbi M, Mieczkowski PA, Marszalek PE. Separating DNA with different topologies by atomic force microscopy in comparison with gel electrophoresis. J Phys Chem B 2010; 114:12162-5. [PMID: 20799746 DOI: 10.1021/jp105603k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomic force microscopy, which is normally used for DNA imaging to gain qualitative results, can also be used for quantitative DNA research, at a single-molecular level. Here, we evaluate the performance of AFM imaging specifically for quantifying supercoiled and relaxed plasmid DNA fractions within a mixture, and compare the results with the bulk material analysis method, gel electrophoresis. The advantages and shortcomings of both methods are discussed in detail. Gel electrophoresis is a quick and well-established quantification method. However, it requires a large amount of DNA, and needs to be carefully calibrated for even slightly different experimental conditions for accurate quantification. AFM imaging is accurate, in that single DNA molecules in different conformations can be seen and counted. When used carefully with necessary correction, both methods provide consistent results. Thus, AFM imaging can be used for DNA quantification, as an alternative to gel electrophoresis.
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Affiliation(s)
- Yong Jiang
- School of Chemistry and Chemical Engineering, Southeast University, Jiangning, Nanjing, Jiangsu 211189, People's Republic of China.
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37
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Mücke N, Klenin K, Kirmse R, Bussiek M, Herrmann H, Hafner M, Langowski J. Filamentous biopolymers on surfaces: atomic force microscopy images compared with Brownian dynamics simulation of filament deposition. PLoS One 2009; 4:e7756. [PMID: 19888472 PMCID: PMC2768466 DOI: 10.1371/journal.pone.0007756] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 09/30/2009] [Indexed: 11/19/2022] Open
Abstract
Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions.
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Affiliation(s)
- Norbert Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Konstantin Klenin
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Robert Kirmse
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Malte Bussiek
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Harald Herrmann
- Department of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany
| | - Mathias Hafner
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim, Mannheim, Germany
| | - Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
- * E-mail:
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38
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Faas FGA, Rieger B, van Vliet LJ, Cherny DI. DNA deformations near charged surfaces: electron and atomic force microscopy views. Biophys J 2009; 97:1148-57. [PMID: 19686663 DOI: 10.1016/j.bpj.2009.06.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 06/03/2009] [Accepted: 06/11/2009] [Indexed: 10/20/2022] Open
Abstract
DNA is a very important cell structural element, which determines the level of expression of genes by virtue of its interaction with regulatory proteins. We use electron (EM) and atomic force microscopy (AFM) to characterize the flexibility of double-stranded DNA ( approximately 150-950 nm long) close to a charged surface. Automated procedures for the extraction of DNA contours ( approximately 10-120 nm for EM data and approximately 10-300 nm for AFM data) combined with new statistical chain descriptors indicate a uniquely two-dimensional equilibration of the molecules on the substrate surface regardless of the procedure of molecule mounting. However, in contrast to AFM, the EM mounting leads to a noticeable decrease in DNA persistence length together with decreased kurtosis. Analysis of local bending on short length scales (down to 6 nm in the EM study) shows that DNA flexibility behaves as predicted by the wormlike chain model. We therefore argue that adhesion of DNA to a charged surface may lead to additional static bending (kinking) of approximately 5 degrees per dinucleotide step without impairing the dynamic behavior of the DNA backbone. Implications of this finding are discussed.
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Affiliation(s)
- F G A Faas
- Department of Imaging Science and Technology Delft University of Technology, Delft, The Netherlands
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39
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Bussiek M, Hoischen C, Diekmann S, Bennink ML. Sequence-specific physical properties of African green monkey alpha-satellite DNA contribute to centromeric heterochromatin formation. J Struct Biol 2009; 167:36-46. [PMID: 19332128 DOI: 10.1016/j.jsb.2009.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 03/06/2009] [Accepted: 03/18/2009] [Indexed: 01/19/2023]
Abstract
Satellite DNA, a major component of eukaryotic centromeric heterochromatin, is potentially associated with the processes ensuring the faithful segregation of the genetic material during cell division. Structural properties of alpha-satellite DNA (AS) from African green monkey (AGM) were studied. Atomic force microscopy imaging showed smaller end-to-end distances of AS fragments than would be expected for the persistence length of random sequence DNA. The apparent persistence length of the AS was determined as 35nm. Gel-electrophoresis indicated only a weak contribution of intrinsic curvature to the DNA conformations suggesting an additional contribution of an elevated bending flexibility to the reduced end-to-end distances. Next, the force-extension behavior of the naked AS and in complex with nucleosomes was studied using optical tweezers. The naked AS showed a reduced overstretching transition force (-18% the value determined for random DNA) and higher forces required to straighten the DNA. Finally, reconstituted AS nucleosomes disrupted at significantly higher forces as compared with random DNA nucleosomes which is probably due to structural properties of the AS which stabilize the nucleosomes. The data support that the AS plays a role in the formation of centromeric heterochromatin due to specific structural properties and suggest that a relatively higher mechanical stability of nucleosomes is important in AGM-AS chromatin.
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Affiliation(s)
- Malte Bussiek
- Department Biophysical Engineering, Faculty of Science and Technology and Mesa+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands. m.bussiek@utwente
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Jiang Y, Rabbi M, Kim M, Ke C, Lee W, Clark RL, Mieczkowski PA, Marszalek PE. UVA generates pyrimidine dimers in DNA directly. Biophys J 2009; 96:1151-8. [PMID: 19186150 DOI: 10.1016/j.bpj.2008.10.030] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 10/31/2008] [Indexed: 10/21/2022] Open
Abstract
There is increasing evidence that UVA radiation, which makes up approximately 95% of the solar UV light reaching the Earth's surface and is also commonly used for cosmetic purposes, is genotoxic. However, in contrast to UVC and UVB, the mechanisms by which UVA produces various DNA lesions are still unclear. In addition, the relative amounts of various types of UVA lesions and their mutagenic significance are also a subject of debate. Here, we exploit atomic force microscopy (AFM) imaging of individual DNA molecules, alone and in complexes with a suite of DNA repair enzymes and antibodies, to directly quantify UVA damage and reexamine its basic mechanisms at a single-molecule level. By combining the activity of endonuclease IV and T4 endonuclease V on highly purified and UVA-irradiated pUC18 plasmids, we show by direct AFM imaging that UVA produces a significant amount of abasic sites and cyclobutane pyrimidine dimers (CPDs). However, we find that only approximately 60% of the T4 endonuclease V-sensitive sites, which are commonly counted as CPDs, are true CPDs; the other 40% are abasic sites. Most importantly, our results obtained by AFM imaging of highly purified native and synthetic DNA using T4 endonuclease V, photolyase, and anti-CPD antibodies strongly suggest that CPDs are produced by UVA directly. Thus, our observations contradict the predominant view that as-yet-unidentified photosensitizers are required to transfer the energy of UVA to DNA to produce CPDs. Our results may help to resolve the long-standing controversy about the origin of UVA-produced CPDs in DNA.
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Affiliation(s)
- Yong Jiang
- Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina, USA
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41
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Díaz-González M, de la Escosura-Muñiz A, González-García MB, Costa-García A. DNA hybridization biosensors using polylysine modified SPCEs. Biosens Bioelectron 2008; 23:1340-6. [PMID: 18207382 PMCID: PMC7127112 DOI: 10.1016/j.bios.2007.12.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 11/04/2007] [Accepted: 12/04/2007] [Indexed: 11/20/2022]
Abstract
Two electrochemical DNA hybridization biosensors (genosensors) for the detection of a 30-mer sequence unique to severe acute respiratory syndrome (SARS) virus are described in this work. Both genosensors rely on the hybridization of the oligonucleotide target with its complementary probe, which is immobilized on positively charged polylysine modified screen-printed carbon electrodes (SPCEs), through electrostatic interactions. In one design, a biotinylated target is used and the detection of the hybridization reaction is monitored using alkaline phosphatase labeled streptavidin (S-AP). This enzyme catalyzes the hydrolysis of the substrate 3-indoxyl phosphate (3-IP) to indigo, which is then solubilized to indigo carmine and detected by means of cyclic voltammetry (CV). In the other design, the target is labeled using an Au(I) complex, sodium aurothiomalate, and the duplex formation is detected by measuring, for first time, the current generated by the hydrogen evolution catalyzed by the gold label. Using 30 min of hybridization time, a detection limit of 8 pM is calculated for the enzymatic genosensor. Although this good sensitivity cannot be reached with the metal label (0.5 nM), the use of this label allows a considerable decrease of the analysis time. Both genosensors do not require the modification of the oligonucleotide probe and using stringent experimental conditions (60 min of hybridization time and 50% formamide in the hybridization buffer) can discriminate between a complementary oligonucleotide and an oligonucleotide with a three-base mismatch.
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Affiliation(s)
- María Díaz-González
- Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006 Oviedo, Asturias, Spain
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Derome A, Hoischen C, Bussiek M, Grady R, Adamczyk M, Kędzierska B, Diekmann S, Barillà D, Hayes F. Centromere anatomy in the multidrug-resistant pathogen Enterococcus faecium. Proc Natl Acad Sci U S A 2008; 105:2151-6. [PMID: 18245388 PMCID: PMC2538891 DOI: 10.1073/pnas.0704681105] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Indexed: 11/18/2022] Open
Abstract
Multidrug-resistant variants of the opportunistic human pathogen Enterococcus have recently emerged as leading agents of nosocomial infection. The acquisition of plasmid-borne resistance genes is a driving force in antibiotic-resistance evolution in enterococci. The segregation locus of a high-level gentamicin-resistance plasmid, pGENT, in Enterococcus faecium was identified and dissected. This locus includes overlapping genes encoding PrgP, a member of the ParA superfamily of segregation proteins, and PrgO, a site-specific DNA binding homodimer that recognizes the cenE centromere upstream of prgPO. The centromere has a distinctive organization comprising three subsites, CESII separates CESI and CESIII, each of which harbors seven TATA boxes spaced by half-helical turns. PrgO independently binds both CESI and CESIII, but with different affinities. The topography of the complex was probed by atomic force microscopy, revealing discrete PrgO foci positioned asymmetrically at the CESI and CESIII subsites. Bending analysis demonstrated that cenE is intrinsically curved. The organization of the cenE site and of certain other plasmid centromeres mirrors that of yeast centromeres, which may reflect a common architectural requirement during assembly of the mitotic apparatus in yeast and bacteria. Moreover, segregation modules homologous to that of pGENT are widely disseminated on vancomycin and other resistance plasmids in enterococci. An improved understanding of segrosome assembly may highlight new interventions geared toward combating antibiotic resistance in these insidious pathogens.
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Affiliation(s)
- Andrew Derome
- *Faculty of Life Sciences and
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Christian Hoischen
- Leibniz Institute for Age Research, Fritz–Lipmann Institute, D-07745 Jena, Germany
| | - Malte Bussiek
- Biophysical Engineering Group, University of Twente, 7500 AE, Enschede, The Netherlands; and
| | | | - Malgorzata Adamczyk
- *Faculty of Life Sciences and
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Barbara Kędzierska
- *Faculty of Life Sciences and
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Stephan Diekmann
- Leibniz Institute for Age Research, Fritz–Lipmann Institute, D-07745 Jena, Germany
| | - Daniela Barillà
- **Department of Biology, University of York, York Y0105 YW, United Kingdom
| | - Finbarr Hayes
- *Faculty of Life Sciences and
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester M1 7DN, United Kingdom
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Ke C, Jiang Y, Mieczkowski PA, Muramoto GG, Chute JP, Marszalek PE. Nanoscale detection of ionizing radiation damage to DNA by atomic force microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2008; 4:288-294. [PMID: 18247386 DOI: 10.1002/smll.200700527] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The detection and quantification of ionizing radiation damage to DNA at a single-molecule level by atomic force microscopy (AFM) is reported. The DNA damage-detection technique combining supercoiled plasmid relaxation assay with AFM imaging is a direct and quantitative approach to detect gamma-ray-induced single- and double-strand breaks in DNA, and its accuracy and reliability are validated through a comparison with traditional agarose gel electrophoresis. In addition, the dependence of radiation-induced single-strand breaks on plasmid size and concentration at a single-molecule level in a low-dose (1 Gy) and low-concentration range (0.01 ng microL(-1)-10 ng microL(-1)) is investigated using the AFM-based damage-detection assay. The results clearly show that the number of single-strand breaks per DNA molecule is linearly proportional to the plasmid size and inversely correlated to the DNA concentration. This assay can also efficiently detect DNA damage in highly dilute samples (0.01 ng microL(-1)), which is beyond the capability of traditional techniques. AFM imaging can uniquely supplement traditional techniques for sensitive measurements of damage to DNA by ionizing radiation.
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Affiliation(s)
- Changhong Ke
- Center for Biologically Inspired Materials and Material Systems and Department of Mechanical, Engineering and Materials Science, Duke University, Durham, NC 27708, USA
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Hoischen C, Bussiek M, Langowski J, Diekmann S. Escherichia coli low-copy-number plasmid R1 centromere parC forms a U-shaped complex with its binding protein ParR. Nucleic Acids Res 2007; 36:607-15. [PMID: 18056157 PMCID: PMC2241845 DOI: 10.1093/nar/gkm672] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Escherichia coli low-copy-number plasmid R1 contains a segregation machinery composed of parC, ParR and parM. The R1 centromere-like site parC contains two separate sets of repeats. By atomic force microscopy (AFM) we show here that ParR molecules bind to each of the 5-fold repeated iterons separately with the intervening sequence unbound by ParR. The two ParR protein complexes on parC do not complex with each other. ParR binds with a stoichiometry of about one ParR dimer per each single iteron. The measured DNA fragment lengths agreed with B-form DNA and each of the two parC 5-fold interon DNA stretches adopts a linear path in its complex with ParR. However, the overall parC/ParR complex with both iteron repeats bound by ParR forms an overall U-shaped structure: the DNA folds back on itself nearly completely, including an angle of ∼150°. Analysing linear DNA fragments, we never observed dimerized ParR complexes on one parC DNA molecule (intramolecular) nor a dimerization between ParR complexes bound to two different parC DNA molecules (intermolecular). This bacterial segrosome is compared to other bacterial segregation complexes. We speculate that partition complexes might have a similar overall structural organization and, at least in part, common functional properties.
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Affiliation(s)
- C Hoischen
- Molecular Biology, FLI, Leibniz-Institute for Age Research, Beutenbergstrasse 11, D-07745 Jena, Germany
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Langowski J, Heermann DW. Computational modeling of the chromatin fiber. Semin Cell Dev Biol 2007; 18:659-67. [PMID: 17936653 DOI: 10.1016/j.semcdb.2007.08.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Accepted: 08/22/2007] [Indexed: 11/17/2022]
Abstract
The packing of the genomic DNA in the living cell is essential for its biological function. While individual aspects of the genome architecture, such as DNA and nucleosome structure or the arrangement of chromosome territories are well studied, much information is missing for a unified description of cellular DNA at all its structural levels. Computer modeling can contribute to such a description. We present here some typical approaches to models of the chromatin fiber, including different amounts of detail in the description of the local nucleosome structure. The main results from our simulations are that the physical properties of the chromatin fiber can be well described by a simplified model consisting of cylinder-like nucleosomes connected by flexible DNA segments, with a geometry determined by the bending and twisting angles between nucleosomes. Randomness in the local geometry - such as random absence of linker histone H1 - leads to a dramatic increase in the chromatin fiber flexibility. Furthermore, we show that chromatin is much more flexible to bending than to stretching, and that the structure of the chromatin fiber favors the formation of sharp bends.
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Affiliation(s)
- Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany.
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Bussiek M, Müller G, Waldeck W, Diekmann S, Langowski J. Organisation of nucleosomal arrays reconstituted with repetitive African green monkey alpha-satellite DNA as analysed by atomic force microscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:81-93. [PMID: 17503032 PMCID: PMC2082062 DOI: 10.1007/s00249-007-0166-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 04/05/2007] [Accepted: 04/14/2007] [Indexed: 10/31/2022]
Abstract
Alpha-satellite DNA (AS) is part of centromeric DNA and could be relevant for centromeric chromatin structure: its repetitive character may generate a specifically ordered nucleosomal arrangement and thereby facilitate kinetochore protein binding and chromatin condensation. Although nucleosomal positioning on some satellite sequences had been shown, including AS from African green monkey (AGM), the sequence-dependent nucleosomal organisation of repetitive AS of this species has so far not been analysed. We therefore studied the positioning of reconstituted nucleosomes on AGM AS tandemly repeated DNA. Enzymatic analysis of nucleosome arrays formed on an AS heptamer as well as the localisation of mononucleosomes on an AS dimer by atomic force microscopy (AFM) showed one major positioning frame, in agreement with earlier results. The occupancy of this site was in the range of 45-50%, in quite good agreement with published in vivo observations. AFM measurements of internucleosomal distances formed on the heptamer indicated that the nucleosomal arrangement is governed by sequence-specific DNA-histone interactions yielding defined internucleosomal distances, which, nevertheless, are not compatible with a uniform phasing of the nucleosomes with the AGM AS repeats.
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Affiliation(s)
- Malte Bussiek
- Biophysical Engineering, Universiteit Twente, PO BOX 217, 7500AE Enschede, The Netherlands
| | - Gabriele Müller
- Division of Biophysics of Macromolecules, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, TP3, 69120 Heidelberg, Germany
| | - Waldemar Waldeck
- Division of Biophysics of Macromolecules, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, TP3, 69120 Heidelberg, Germany
| | - Stephan Diekmann
- Division of Molecular Biology, Fritz Lipmann Institut, Beutenbergstraße 11, 07708 Jena, Germany
| | - Jörg Langowski
- Division of Biophysics of Macromolecules, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, TP3, 69120 Heidelberg, Germany
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Jiang Y, Ke C, Mieczkowski PA, Marszalek PE. Detecting ultraviolet damage in single DNA molecules by atomic force microscopy. Biophys J 2007; 93:1758-67. [PMID: 17483180 PMCID: PMC1948057 DOI: 10.1529/biophysj.107.108209] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report detection and quantification of ultraviolet (UV) damage in DNA at a single molecule level by atomic force microscopy (AFM). By combining the supercoiled plasmid relaxation assay with AFM imaging, we find that high doses of medium wave ultraviolet (UVB) and short wave ultraviolet (UVC) light not only produce cyclobutane pyrimidine dimers (CPDs) as reported but also cause significant DNA degradation. Specifically, 12.5 kJ/m(2) of UVC and 165 kJ/m(2) of UVB directly relax 95% and 78% of pUC18 supercoiled plasmids, respectively. We also use a novel combination of the supercoiled plasmid assay with T4 Endonuclease V treatment of irradiated plasmids and AFM imaging of their relaxation to detect damage caused by low UVB doses, which on average produced approximately 0.5 CPD per single plasmid. We find that at very low UVB doses, the relationship between the number of CPDs and UVB dose is almost linear, with 4.4 CPDs produced per Mbp per J/m(2) of UVB radiation. We verified these AFM results by agarose gel electrophoresis separation of UV-irradiated and T4 Endonuclease V treated plasmids. Our AFM and gel electrophoresis results are consistent with the previous result obtained using other traditional DNA damage detection methods. We also show that damage detection assay sensitivity increases with plasmid size. In addition, we used photolyase to mark the sites of UV lesions in supercoiled plasmids for detection and quantification by AFM, and these results were found to be consistent with the results obtained by the plasmid relaxation assay. Our results suggest that AFM can supplement traditional methods for high resolution measurements of UV damage to DNA.
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Affiliation(s)
- Yong Jiang
- Center for Biologically Inspired Materials and Material Systems and Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
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48
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Liu J, Tiefenauer L, Tian S, Nielsen PE, Knoll W. PNA-DNA hybridization study using labeled streptavidin by voltammetry and surface plasmon fluorescence spectroscopy. Anal Chem 2007; 78:470-6. [PMID: 16408929 DOI: 10.1021/ac051299c] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using ferrocene-streptavidin conjugates as amplifiers, we recently have demonstrated the simultaneous detection of DNA hybridization to peptide nucleic acid (PNA)-modified gold surfaces at the femtomole level by electrochemical and surface plasmon resonance techniques (Liu, J.; Tian, S.; Tiefenauer, L.; Nielsen, P. E.; Knoll, W. Anal. Chem. 2005, 77, 2756-2761). In this paper, a detailed study of the binding behavior of PNA-DNA is presented by square wave voltammetry and surface plasmon field-enhanced fluorescence spectroscopy (SPFS). The different binding constants for fully matched and single-mismatched DNA were obtained. The effect of the buffer concentration on the PNA-DNA hybrids was investigated using labeled streptavidin by cyclic voltammetry (CV) and SPFS. At high ionic strength, both the CV and SPFS signals were restrained dramatically, which is most probably due to a conformational change of the short-strand PNA-DNA helices on the surface. We conclude that the combination of electrochemical techniques with SPFS is very useful for the study of short DNA structure transformation.
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Affiliation(s)
- Jianyun Liu
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany.
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50
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Nanoprocessability of a one-dimensional oxalato-bridged cobalt(II) complex with 1,2,4-triazole. Inorganica Chim Acta 2007. [DOI: 10.1016/j.ica.2006.07.065] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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