1
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Dubrovin EV. Atomic force microscopy-based approaches for single-molecule investigation of nucleic acid- protein complexes. Biophys Rev 2023; 15:1015-1033. [PMID: 37974971 PMCID: PMC10643717 DOI: 10.1007/s12551-023-01111-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/07/2023] [Indexed: 11/19/2023] Open
Abstract
The interaction of nucleic acids with proteins plays an important role in many fundamental biological processes in living cells, including replication, transcription, and translation. Therefore, understanding nucleic acid-protein interaction is of high relevance in many areas of biology, medicine and technology. During almost four decades of its existence atomic force microscopy (AFM) accumulated a significant experience in investigation of biological molecules at a single-molecule level. AFM has become a powerful tool of molecular biology and biophysics providing unique information about properties, structure, and functioning of biomolecules. Despite a great variety of nucleic acid-protein systems under AFM investigations, there are a number of typical approaches for such studies. This review is devoted to the analysis of the typical AFM-based approaches of investigation of DNA (RNA)-protein complexes with a major focus on transcription studies. The basic strategies of AFM analysis of nucleic acid-protein complexes including investigation of the products of DNA-protein reactions and real-time dynamics of DNA-protein interaction are categorized and described by the example of the most relevant research studies. The described approaches and protocols have many universal features and, therefore, are applicable for future AFM studies of various nucleic acid-protein systems.
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Affiliation(s)
- Evgeniy V. Dubrovin
- Lomonosov Moscow State University, Leninskie Gory 1 Bld. 2, 119991 Moscow, Russian Federation
- Moscow Institute of Physics and Technology, Institutskiy Per. 9, Dolgoprudny, 141700 Russian Federation
- Sirius University of Science and Technology, Olimpiyskiy Ave 1, Township Sirius, Krasnodar Region, 354349 Russia
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2
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Vemulapalli S, Hashemi M, Kolomeisky AB, Lyubchenko YL. Assembly of Synaptic Protein-DNA Complexes: Critical Role of Non-Specific Interactions. Int J Mol Sci 2023; 24:9800. [PMID: 37372946 DOI: 10.3390/ijms24129800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 05/31/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
The synaptic protein-DNA complexes, formed by specialized proteins that bridge two or more distant sites on DNA, are critically involved in various genetic processes. However, the molecular mechanism by which the protein searches for these sites and how it brings them together is not well understood. Our previous studies directly visualized search pathways used by SfiI, and we identified two pathways, DNA threading and site-bound transfer pathways, specific to the site-search process for synaptic DNA-protein systems. To investigate the molecular mechanism behind these site-search pathways, we assembled complexes of SfiI with various DNA substrates corresponding to different transient states and measured their stability using a single-molecule fluorescence approach. These assemblies corresponded to specific-specific (synaptic), non-specific-non-specific (non-specific), and specific-non-specific (pre-synaptic) SfiI-DNA states. Unexpectedly, an elevated stability in pre-synaptic complexes assembled with specific and non-specific DNA substrates was found. To explain these surprising observations, a theoretical approach that describes the assembly of these complexes and compares the predictions with the experiment was developed. The theory explains this effect by utilizing entropic arguments, according to which, after the partial dissociation, the non-specific DNA template has multiple possibilities of rebinding, effectively increasing the stability. Such difference in the stabilities of SfiI complexes with specific and non-specific DNA explains the utilization of threading and site-bound transfer pathways in the search process of synaptic protein-DNA complexes discovered in the time-lapse AFM experiments.
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Affiliation(s)
- Sridhar Vemulapalli
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Mohtadin Hashemi
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Anatoly B Kolomeisky
- Department of Chemistry-MS60, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
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3
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Cheung E, Xia Y, Caporini MA, Gilmore JL. Tools shaping drug discovery and development. BIOPHYSICS REVIEWS 2022; 3:031301. [PMID: 38505278 PMCID: PMC10903431 DOI: 10.1063/5.0087583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 06/21/2022] [Indexed: 03/21/2024]
Abstract
Spectroscopic, scattering, and imaging methods play an important role in advancing the study of pharmaceutical and biopharmaceutical therapies. The tools more familiar to scientists within industry and beyond, such as nuclear magnetic resonance and fluorescence spectroscopy, serve two functions: as simple high-throughput techniques for identification and purity analysis, and as potential tools for measuring dynamics and structures of complex biological systems, from proteins and nucleic acids to membranes and nanoparticle delivery systems. With the expansion of commercial small-angle x-ray scattering instruments into the laboratory setting and the accessibility of industrial researchers to small-angle neutron scattering facilities, scattering methods are now used more frequently in the industrial research setting, and probe-less time-resolved small-angle scattering experiments are now able to be conducted to truly probe the mechanism of reactions and the location of individual components in complex model or biological systems. The availability of atomic force microscopes in the past several decades enables measurements that are, in some ways, complementary to the spectroscopic techniques, and wholly orthogonal in others, such as those related to nanomechanics. As therapies have advanced from small molecules to protein biologics and now messenger RNA vaccines, the depth of biophysical knowledge must continue to serve in drug discovery and development to ensure quality of the drug, and the characterization toolbox must be opened up to adapt traditional spectroscopic methods and adopt new techniques for unraveling the complexities of the new modalities. The overview of the biophysical methods in this review is meant to showcase the uses of multiple techniques for different modalities and present recent applications for tackling particularly challenging situations in drug development that can be solved with the aid of fluorescence spectroscopy, nuclear magnetic resonance spectroscopy, atomic force microscopy, and small-angle scattering.
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Affiliation(s)
- Eugene Cheung
- Moderna, 200 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Yan Xia
- Moderna, 200 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Marc A. Caporini
- Moderna, 200 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Jamie L. Gilmore
- Moderna, 200 Technology Square, Cambridge, Massachusetts 02139, USA
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4
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Site-Search Process for Synaptic Protein-DNA Complexes. Int J Mol Sci 2021; 23:ijms23010212. [PMID: 35008637 PMCID: PMC8745619 DOI: 10.3390/ijms23010212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/18/2021] [Accepted: 12/22/2021] [Indexed: 11/20/2022] Open
Abstract
The assembly of synaptic protein-DNA complexes by specialized proteins is critical for bringing together two distant sites within a DNA molecule or bridging two DNA molecules. The assembly of such synaptosomes is needed in numerous genetic processes requiring the interactions of two or more sites. The molecular mechanisms by which the protein brings the sites together, enabling the assembly of synaptosomes, remain unknown. Such proteins can utilize sliding, jumping, and segmental transfer pathways proposed for the single-site search process, but none of these pathways explains how the synaptosome assembles. Here we used restriction enzyme SfiI, that requires the assembly of synaptosome for DNA cleavage, as our experimental system and applied time-lapse, high-speed AFM to directly visualize the site search process accomplished by the SfiI enzyme. For the single-site SfiI-DNA complexes, we were able to directly visualize such pathways as sliding, jumping, and segmental site transfer. However, within the synaptic looped complexes, we visualized the threading and site-bound segment transfer as the synaptosome-specific search pathways for SfiI. In addition, we visualized sliding and jumping pathways for the loop dissociated complexes. Based on our data, we propose the site-search model for synaptic protein-DNA systems.
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5
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Yang XW, Liu J. Observing Protein One-Dimensional Sliding: Methodology and Biological Significance. Biomolecules 2021; 11:1618. [PMID: 34827616 PMCID: PMC8615959 DOI: 10.3390/biom11111618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/15/2021] [Accepted: 10/16/2021] [Indexed: 11/28/2022] Open
Abstract
One-dimensional (1D) sliding of DNA-binding proteins has been observed by numerous kinetic studies. It appears that many of these sliding events play important roles in a wide range of biological processes. However, one challenge is to determine the physiological relevance of these motions in the context of the protein's biological function. Here, we discuss methods of measuring protein 1D sliding by highlighting the single-molecule approaches that are capable of visualizing particle movement in real time. We also present recent findings that show how protein sliding contributes to function.
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Affiliation(s)
| | - Jiaquan Liu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China;
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6
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Yu Y, Yoshimura SH. Investigating the morphological dynamics of the plasma membrane by high-speed atomic force microscopy. J Cell Sci 2021; 134:272010. [PMID: 34468000 DOI: 10.1242/jcs.243584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Despite numerous recent developments in bioimaging techniques, nanoscale and live-cell imaging of the plasma membrane has been challenging because of the insufficient z-resolution of optical microscopes, as well as the lack of fluorescent probes to specifically label small membrane structures. High-speed atomic force microscopy (HS-AFM) is a powerful tool for visualising the dynamics of a specimen surface and is therefore suitable for observing plasma membrane dynamics. Recent developments in HS-AFM for live-cell imaging have enabled the visualisation of the plasma membrane and the network of cortical actin underneath the membrane in a living cell. Furthermore, correlative imaging with fluorescence microscopy allows for the direct visualisation of morphological changes of the plasma membrane together with the dynamic assembly or disassembly of proteins during the entire course of endocytosis in a living cell. Here, we review these recent advances in HS-AFM in order to analyse various cellular events occurring at the cell surface.
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Affiliation(s)
- Yiming Yu
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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7
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Folding RNA-Protein Complex into Designed Nanostructures. Methods Mol Biol 2021. [PMID: 34086284 DOI: 10.1007/978-1-0716-1499-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
RNA-protein (RNP) complexes are promising biomaterials for the fields of nanotechnology and synthetic biology. Protein-responsive RNA sequences (RNP motifs) can be integrated into various RNAs, such as messenger RNA, short-hairpin RNA, and synthetic RNA nanoobjects for a variety of purposes. Direct observation of RNP interaction in solution at high resolution is important in the design and construction of RNP-mediated nanostructures. Here we describe a method to construct and visualize RNP nanostructures that precisely arrange a target protein on the RNA scaffold with nanometer scale. High-speed AFM (HS-AFM) images of RNP nanostructures show that the folding of RNP complexes of defined sizes can be directly visualized at single RNP resolution in solution.
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8
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Vemulapalli S, Hashemi M, Kolomeisky AB, Lyubchenko YL. DNA Looping Mediated by Site-Specific SfiI-DNA Interactions. J Phys Chem B 2021; 125:4645-4653. [PMID: 33914533 DOI: 10.1021/acs.jpcb.1c00763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interactions between distant DNA segments play important roles in various biological processes, such as DNA recombination. Certain restriction enzymes create DNA loops when two sites are held together and then cleave the DNA. DNA looping is important during DNA synapsis. Here we investigated the mechanisms of DNA looping by restriction enzyme SfiI by measuring the properties of the system at various temperatures. Different sized loop complexes, mediated by SfiI-DNA interactions, were visualized with AFM. The experimental results revealed that small loops are more favorable compared to other loop sizes at all temperatures. Our theoretical model found that entropic cost dominates at all conditions, which explains the preference for short loops. Furthermore, specific loop sizes were predicted as favorable from an energetic point of view. These predictions were tested by experiments with transiently assembled SfiI loops on a substrate with a single SfiI site.
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Affiliation(s)
- Sridhar Vemulapalli
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Mohtadin Hashemi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Anatoly B Kolomeisky
- Department of Chemistry-MS60, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
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9
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Duic I, Tadakuma H, Harada Y, Yamaue R, Deguchi K, Suzuki Y, Yoshimura SH, Kato H, Takeyasu K, Fujita T. Viral RNA recognition by LGP2 and MDA5, and activation of signaling through step-by-step conformational changes. Nucleic Acids Res 2021; 48:11664-11674. [PMID: 33137199 PMCID: PMC7672446 DOI: 10.1093/nar/gkaa935] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 10/03/2020] [Accepted: 10/20/2020] [Indexed: 12/20/2022] Open
Abstract
Cytoplasmic RIG-I-like receptor (RLR) proteins in mammalian cells recognize viral RNA and initiate an antiviral response that results in IFN-β induction. Melanoma differentiation-associated protein 5 (MDA5) forms fibers along viral dsRNA and propagates an antiviral response via a signaling domain, the tandem CARD. The most enigmatic RLR, laboratory of genetics and physiology (LGP2), lacks the signaling domain but functions in viral sensing through cooperation with MDA5. However, it remains unclear how LGP2 coordinates fiber formation and subsequent MDA5 activation. We utilized biochemical and biophysical approaches to observe fiber formation and the conformation of MDA5. LGP2 facilitated MDA5 fiber assembly. LGP2 was incorporated into the fibers with an average inter-molecular distance of 32 nm, suggesting the formation of hetero-oligomers with MDA5. Furthermore, limited protease digestion revealed that LGP2 induces significant conformational changes on MDA5, promoting exposure of its CARDs. Although the fibers were efficiently dissociated by ATP hydrolysis, MDA5 maintained its active conformation to participate in downstream signaling. Our study demonstrated the coordinated actions of LGP2 and MDA5, where LGP2 acts as an MDA5 nucleator and requisite partner in the conversion of MDA5 to an active conformation. We revealed a mechanistic basis for LGP2-mediated regulation of MDA5 antiviral innate immune responses.
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Affiliation(s)
- Ivana Duic
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.,Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8397, Japan
| | - Hisashi Tadakuma
- Division of Protein Chemistry, Institute for Protein Research, Osaka University, Osaka 565-0871, Japan.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yoshie Harada
- Division of Protein Chemistry, Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Ryo Yamaue
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.,Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8397, Japan
| | - Katashi Deguchi
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Yuki Suzuki
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shige H Yoshimura
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroki Kato
- Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8397, Japan.,Institute for Cardiovascular Immunology, University Hospital Bonn, University of Bonn, Bonn 53127, Germany
| | - Kunio Takeyasu
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Takashi Fujita
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.,Laboratory of Molecular Genetics, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8397, Japan.,Institute for Cardiovascular Immunology, University Hospital Bonn, University of Bonn, Bonn 53127, Germany
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10
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Endo M. AFM-based single-molecule observation of the conformational changes of DNA structures. Methods 2019; 169:3-10. [PMID: 30978504 DOI: 10.1016/j.ymeth.2019.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/01/2019] [Accepted: 04/05/2019] [Indexed: 01/26/2023] Open
Abstract
Direct visualization of the biomolecules of interest is a straightforward way to elucidate the physical properties of individual molecules and their reaction processes. Atomic force microscopy (AFM) enables direct imaging of biomolecules in suitable solution conditions. As AFM visualizes the molecules at a nanometer-scale spatial resolution, a versatile observation platform is required for precise imaging of the molecules in action. The DNA origami technology allows precise placement of target molecules in a designed nanostructure, enabling their detection at the single-molecule level. We used DNA origami technology for visualizing the detailed movement of target molecules in reactions using high-speed AFM (HS-AFM), which enables the analysis of dynamic movement of biomolecules with a subsecond time resolution. By combining the DNA origami system and HS-AFM, DNA conformational changes, including G-quadruplex formation and disruption and B-Z transition, were visualized. In addition, enzyme-based reactions such as DNA recombination were also visualized at the single-molecule level using this combined observation system. Moreover, the enzyme-based reaction could be directly regulated in the DNA origami frame by imposing structural stress on the substrate DNAs to elucidate the reaction mechanism. These target-orientated observation systems should contribute to a detailed analysis of biomolecular motions in real time at molecular resolution.
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Affiliation(s)
- Masayuki Endo
- Department of Chemistry, Graduate School of Science, Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan.
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11
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Stumme-Diers MP, Stormberg T, Sun Z, Lyubchenko YL. Probing The Structure And Dynamics Of Nucleosomes Using Atomic Force Microscopy Imaging. J Vis Exp 2019. [PMID: 30774135 DOI: 10.3791/58820] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chromatin, which is a long chain of nucleosome subunits, is a dynamic system that allows for such critical processes as DNA replication and transcription to take place in eukaryotic cells. The dynamics of nucleosomes provides access to the DNA by replication and transcription machineries, and critically contributes to the molecular mechanisms underlying chromatin functions. Single-molecule studies such as atomic force microscopy (AFM) imaging have contributed significantly to our current understanding of the role of nucleosome structure and dynamics. The current protocol describes the steps enabling high-resolution AFM imaging techniques to study the structural and dynamic properties of nucleosomes. The protocol is illustrated by AFM data obtained for the centromere nucleosomes in which H3 histone is replaced with its counterpart centromere protein A (CENP-A). The protocol starts with the assembly of mono-nucleosomes using a continuous dilution method. The preparation of the mica substrate functionalized with aminopropyl silatrane (APS-mica) that is used for the nucleosome imaging is critical for the AFM visualization of nucleosomes described and the procedure to prepare the substrate is provided. Nucleosomes deposited on the APS-mica surface are first imaged using static AFM, which captures a snapshot of the nucleosome population. From analyses of these images, such parameters as the size of DNA wrapped around the nucleosomes can be measured and this process is also detailed. The time-lapse AFM imaging procedure in the liquid is described for the high-speed time-lapse AFM that can capture several frames of nucleosome dynamics per second. Finally, the analysis of nucleosome dynamics enabling the quantitative characterization of the dynamic processes is described and illustrated.
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Affiliation(s)
| | - Tommy Stormberg
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center
| | - Zhiqiang Sun
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center;
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12
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Gilmore JL, Yoshida A, Hejna JA, Takeyasu K. Visualization of conformational variability in the domains of long single-stranded RNA molecules. Nucleic Acids Res 2017; 45:8493-8507. [PMID: 28591846 PMCID: PMC5737216 DOI: 10.1093/nar/gkx502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 06/04/2017] [Indexed: 01/05/2023] Open
Abstract
We demonstrate an application of atomic force microscopy (AFM) for the structural analysis of long single-stranded RNA (>1 kb), focusing on 28S ribosomal RNA (rRNA). Generally, optimization of the conditions required to obtain three-dimensional (3D) structures of long RNA molecules is a challenging or nearly impossible process. In this study, we overcome these limitations by developing a method using AFM imaging combined with automated, MATLAB-based image analysis algorithms for extracting information about the domain organization of single RNA molecules. We examined the 5 kb human 28S rRNA since it is the largest RNA molecule for which a 3D structure is available. As a proof of concept, we determined a domain structure that is in accordance with previously described secondary structural models. Importantly, we identified four additional small (200–300 nt), previously unreported domains present in these molecules. Moreover, the single-molecule nature of our method enabled us to report on the relative conformational variability of each domain structure identified, and inter-domain associations within subsets of molecules leading to molecular compaction, which may shed light on the process of how these molecules fold into the final tertiary structure.
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Affiliation(s)
- Jamie L Gilmore
- Laboratory of Plasma Membrane and Nuclear Signaling, Kyoto University Graduate School of Biostudies, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Aiko Yoshida
- Laboratory of Plasma Membrane and Nuclear Signaling, Kyoto University Graduate School of Biostudies, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - James A Hejna
- Laboratory of Science Communication, Kyoto University Graduate School of Biostudies, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kunio Takeyasu
- Laboratory of Plasma Membrane and Nuclear Signaling, Kyoto University Graduate School of Biostudies, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.,Institute of Biotechnology, National Taiwan University, 4F, No. 81, Chang-Xing St, Taipei 106, Taiwan
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13
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Zhang Y, Yoshida A, Sakai N, Uekusa Y, Kumeta M, Yoshimura SH. In vivo dynamics of the cortical actin network revealed by fast-scanning atomic force microscopy. Microscopy (Oxf) 2017; 66:272-282. [DOI: 10.1093/jmicro/dfx015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/29/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yanshu Zhang
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Aiko Yoshida
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | - Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H. Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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14
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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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15
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Studying RNAP–promoter interactions using atomic force microscopy. Methods 2015; 86:4-9. [DOI: 10.1016/j.ymeth.2015.05.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/15/2015] [Accepted: 05/18/2015] [Indexed: 01/02/2023] Open
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16
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Analyses of nuclear proteins and nucleic acid structures using atomic force microscopy. Methods Mol Biol 2015; 1262:119-53. [PMID: 25555579 DOI: 10.1007/978-1-4939-2253-6_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Since the inception of atomic force microscopy (AFM) in 1986, the value of this technology for exploring the structure and biophysical properties of a variety of biological samples has been increasingly recognized. AFM provides the opportunity to both image samples at nanometer resolution and also measure the forces on the surface of the sample. Here, we describe a variety of methods for studying nuclear samples including single nucleic acid molecules, higher-order chromatin structures, the nucleolus, and the nucleus. Protocols to prepare nucleic acids, nucleic acid-protein complexes, reconstituted chromatin, the cell nucleus, and the nucleolus are included, as well as protocols describing how to prepare the AFM substrate and the AFM tip. Finally, we describe how to perform conventional imaging, high-speed imaging, recognition imaging, force spectroscopy, and nanoindentation experiments.
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17
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Shibata T, Suzuki Y, Sugiyama H, Endo M, Saito H. Folding RNA-Protein Complex into Designed Nanostructures. Methods Mol Biol 2015; 1316:169-79. [PMID: 25967061 DOI: 10.1007/978-1-4939-2730-2_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RNA-protein (RNP) complexes are promising biomaterials for the fields of nanotechnology and synthetic biology. Protein-responsive RNA sequences (RNP motifs) can be integrated into various RNAs, such as messenger RNA, short-hairpin RNA, and synthetic RNA nano-objects for a variety of purposes. Direct observation of RNP interaction in solution at high resolution is important in the design and construction of RNP-mediated nanostructures. Here we describe a method to construct and visualize RNP nanostructures that precisely arrange a target protein on the RNA scaffold with nanometer scale. High-speed AFM (HS-AFM) images of RNP nanostructures show that the folding of RNP complexes of defined sizes can be directly visualized at single RNP resolution in solution.
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Affiliation(s)
- Tomonori Shibata
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
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Ando T. High-speed AFM imaging. Curr Opin Struct Biol 2014; 28:63-8. [DOI: 10.1016/j.sbi.2014.07.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 07/22/2014] [Accepted: 07/22/2014] [Indexed: 11/26/2022]
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19
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Osada E, Suzuki Y, Hidaka K, Ohno H, Sugiyama H, Endo M, Saito H. Engineering RNA-protein complexes with different shapes for imaging and therapeutic applications. ACS NANO 2014; 8:8130-8140. [PMID: 25058166 DOI: 10.1021/nn502253c] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Molecular machines composed of RNA–protein (RNP) complexes may expand the fields of molecular robotics, nanomedicine, and synthetic biology. However, constructing and directly visualizing a functional RNP nanostructure to detect and control living cell function remains a challenge. Here we show that RNP nanostructures with modular functions can be designed and visualized at single-RNP resolution in real time. The RNP structural images collected in solution through high-speed atomic force microscopy showed that a single RNP interaction induces a conformational change in the RNA scaffold, which supports the nanostructure formation designed. The specific RNP interaction also improved RNA nanostructure stability in a serum-containing buffer. We developed and visualized functional RNPs (e.g., to detect human cancer cells or knockdown target genes) by attaching a protein or RNA module to the same RNA scaffold of an optimal size. The synthetic RNP architecture may provide alternative materials to detect and control functions in target mammalian cells.
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20
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Endo M, Sugiyama H. Single-molecule imaging of dynamic motions of biomolecules in DNA origami nanostructures using high-speed atomic force microscopy. Acc Chem Res 2014; 47:1645-53. [PMID: 24601497 DOI: 10.1021/ar400299m] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONSPECTUS: Direct imaging of molecular motions is one of the most fundamental issues for elucidating the physical properties of individual molecules and their reaction mechanisms. Atomic force microscopy (AFM) enables direct molecular imaging, especially for biomolecules in the physiological environment. Because AFM can visualize the molecules at nanometer-scale spatial resolution, a versatile observation scaffold is needed for the precise imaging of molecule interactions in the reactions. The emergence of DNA origami technology allows the precise placement of desired molecules in the designed nanostructures and enables molecules to be detected at the single-molecule level. In our study, the DNA origami system was applied to visualize the detailed motions of target molecules in reactions using high-speed AFM (HS-AFM), which enables the analysis of dynamic motions of biomolecules in a subsecond time resolution. In this system, biochemical properties such as the placement of various double-stranded DNAs (dsDNAs) containing unrestricted DNA sequences, modified nucleosides, and chemical functions can be incorporated. From a physical point of view, the tension and rotation of dsDNAs can be controlled by placement into the DNA nanostructures. From a topological point of view, the orientations of dsDNAs and various shapes of dsDNAs including Holliday junctions can be incorporated for studies on reaction mechanisms. In this Account, we describe the combination of the DNA origami system and HS-AFM for imaging various biochemical reactions including enzymatic reactions and DNA structural changes. To observe the behaviors and reactions of DNA methyltransferase and DNA repair enzymes, the substrate dsDNAs were incorporated into the cavity of the DNA frame, and the enzymes that bound to the target dsDNA were observed using HS-AFM. DNA recombination was also observed using the recombination substrates and Holliday junction intermediates placed in the DNA frame, and the direction of the reactions was controlled by introducing structural stress to the substrates. In addition, the movement of RNA polymerase and its reaction were visualized using a template dsDNA attached to the origami structure. To observe DNA structural changes, G-quadruplex formation and disruption, the switching behaviors of photoresponsive oligonucleotides, and B-Z transition were visualized using the DNA frame observation system. For the formation and disruption of G-quadruplex and double-helix DNA, the two dsDNA chains incorporated into the DNA frame could amplify the small structural change to the global structural change, which enabled the visualization of their association and dissociation by HS-AFM. The dynamic motion of the helical rotation induced by the B-Z transition was also directly imaged in the DNA frame. Furthermore, the stepwise motions of mobile DNA along the DNA track were visualized on the DNA origami surface. These target-orientated observation systems should contribute to the detailed analysis of biomolecule motions in real time and at molecular resolution.
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Affiliation(s)
- Masayuki Endo
- Institute
for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho,
Sakyo-ku, Kyoto 606-8501, Japan
- CREST, Japan Science and Technology Corporation (JST), Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Hiroshi Sugiyama
- Institute
for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho,
Sakyo-ku, Kyoto 606-8501, Japan
- Department
of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho,
Sakyo-ku, Kyoto 606-8502, Japan
- CREST, Japan Science and Technology Corporation (JST), Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
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21
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Ando T, Uchihashi T, Scheuring S. Filming biomolecular processes by high-speed atomic force microscopy. Chem Rev 2014; 114:3120-88. [PMID: 24476364 PMCID: PMC4076042 DOI: 10.1021/cr4003837] [Citation(s) in RCA: 239] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Toshio Ando
- Department of Physics, and Bio-AFM Frontier
Research Center, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
- CREST,
Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
| | - Takayuki Uchihashi
- Department of Physics, and Bio-AFM Frontier
Research Center, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
- CREST,
Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
| | - Simon Scheuring
- U1006
INSERM/Aix-Marseille Université, Parc Scientifique et Technologique
de Luminy Bâtiment Inserm TPR2 bloc 5, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
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22
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Lyubchenko YL, Gall AA, Shlyakhtenko LS. Visualization of DNA and protein-DNA complexes with atomic force microscopy. Methods Mol Biol 2014; 1117:367-84. [PMID: 24357372 DOI: 10.1007/978-1-62703-776-1_17] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
This article describes sample preparation techniques for AFM imaging of DNA and protein-DNA complexes. The approach is based on chemical functionalization of the mica surface with aminopropyl silatrane (APS) to yield an APS-mica surface. This surface binds nucleic acids and nucleoprotein complexes in a wide range of ionic strengths, in the absence of divalent cations, and in a broad range of pH. The chapter describes the methodologies for the preparation of APS-mica surfaces and the preparation of samples for AFM imaging. The protocol for synthesis and purification of APS is also provided. The AFM applications are illustrated with examples of images of DNA and protein-DNA complexes.
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Affiliation(s)
- Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, USA
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23
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Rajendran A, Endo M, Sugiyama H. State-of-the-Art High-Speed Atomic Force Microscopy for Investigation of Single-Molecular Dynamics of Proteins. Chem Rev 2013; 114:1493-520. [DOI: 10.1021/cr300253x] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Arivazhagan Rajendran
- Department
of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho
Sakyo-ku, Kyoto 606-8502, Japan
| | - Masayuki Endo
- Institute
for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho,
Sakyo-ku, Kyoto 606-8501, Japan
- CREST, Japan Science and Technology Corporation (JST), Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Hiroshi Sugiyama
- Department
of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho
Sakyo-ku, Kyoto 606-8502, Japan
- Institute
for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho,
Sakyo-ku, Kyoto 606-8501, Japan
- CREST, Japan Science and Technology Corporation (JST), Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
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24
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High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events. Sci Rep 2013; 3:2131. [PMID: 23823461 PMCID: PMC3701170 DOI: 10.1038/srep02131] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/10/2013] [Indexed: 11/08/2022] Open
Abstract
A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events.
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Rajendran A, Endo M, Hidaka K, Tran PLT, Mergny JL, Sugiyama H. Controlling the stoichiometry and strand polarity of a tetramolecular G-quadruplex structure by using a DNA origami frame. Nucleic Acids Res 2013; 41:8738-47. [PMID: 23863846 PMCID: PMC3794576 DOI: 10.1093/nar/gkt592] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Guanine-rich oligonucleotides often show a strong tendency to form supramolecular architecture, the so-called G-quadruplex structure. Because of the biological significance, it is now considered to be one of the most important conformations of DNA. Here, we describe the direct visualization and single-molecule analysis of the formation of a tetramolecular G-quadruplex in KCl solution. The conformational changes were carried out by incorporating two duplex DNAs, with G-G mismatch repeats in the middle, inside a DNA origami frame and monitoring the topology change of the strands. In the absence of KCl, incorporated duplexes had no interaction and laid parallel to each other. Addition of KCl induced the formation of a G-quadruplex structure by stably binding the duplexes to each other in the middle. Such a quadruplex formation allowed the DNA synapsis without disturbing the duplex regions of the participating sequences, and resulted in an X-shaped structure that was monitored by atomic force microscopy. Further, the G-quadruplex formation in KCl solution and its disruption in KCl-free buffer were analyzed in real-time. The orientation of the G-quadruplex is often difficult to control and investigate using traditional biochemical methods. However, our method using DNA origami could successfully control the strand orientations, topology and stoichiometry of the G-quadruplex.
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Affiliation(s)
- Arivazhagan Rajendran
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan, Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan, CREST, Japan Science and Technology Corporation (JST), Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan and University of Bordeaux, INSERM, U869, ARNA Laboratory, 2 rue Robert Escarpit, Pessac, F-33607, France
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Abstract
Directly observing individual protein molecules in action at high spatiotemporal resolution has long been a holy grail for biological science. This is because we long have had to infer how proteins function from the static snapshots of their structures and dynamic behavior of optical makers attached to the molecules. This limitation has recently been removed to a large extent by the materialization of high-speed atomic force microscopy (HS-AFM). HS-AFM allows us to directly visualize the structure dynamics and dynamic processes of biological molecules in physiological solutions, at subsecond to sub-100-ms temporal resolution, without disturbing their function. In fact, dynamically acting molecules such as myosin V walking on an actin filament and bacteriorhodopsin in response to light are successfully visualized. In this review, we first describe theoretical considerations for the highest possible imaging rate of this new microscope, and then highlight recent imaging studies. Finally, the current limitation and future challenges to explore are described.
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Affiliation(s)
- Toshio Ando
- Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan.
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27
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Molecular machines directly observed by high-speed atomic force microscopy. FEBS Lett 2013; 587:997-1007. [PMID: 23318713 DOI: 10.1016/j.febslet.2012.12.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 11/22/2022]
Abstract
Molecular machines made of proteins are highly dynamic and carry out sophisticated biological functions. The direct and dynamic high-resolution visualization of molecular machines in action is considered to be the most straightforward approach to understanding how they function but this has long been infeasible until recently. High-speed atomic force microscopy has recently been realized, making such visualization possible. The captured images of myosin V, F1-ATPase, and bacteriorhodopsin have enabled their dynamic processes and structure dynamics to be revealed in great detail, giving unique and deep insights into their functional mechanisms.
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Abstract
High-speed atomic force microscopy (HS-AFM) has been developed as a nano-dynamics visualization technique. This microscopy permits direct observation of structure dynamics and dynamic processes of biological molecules in physiological solutions, at a subsecond to sub-100 ms temporal resolution and an ∼2 nm lateral and a 0.1 nm vertical resolution. Importantly, tip-sample interactions do not disturb the biomolecules' functions. Various functioning proteins including myosin V walking on an actin filament and bacteriorhodopsin responding to light have been successfully visualized with HS-AFM. In the quest for understanding the functional mechanisms of proteins, inferences no longer have to be made from static snapshots of molecular structures and dynamic behavior of optical markers attached to proteins. High-resolution molecular movies obtained from HS-AFM observations reveal the details of molecules' dynamic behavior in action, without the need for intricate analyses and interpretations. In this review, I first describe the fundamentals behind the achieved high imaging rate and low invasiveness to samples, and then highlight recent imaging studies. Finally, future studies are briefly described.
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Affiliation(s)
- Toshio Ando
- Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa, Japan.
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Shlyakhtenko LS, Lushnikov AY, Miyagi A, Li M, Harris RS, Lyubchenko YL. Nanoscale structure and dynamics of ABOBEC3G complexes with single-stranded DNA. Biochemistry 2012; 51:6432-40. [PMID: 22809226 DOI: 10.1021/bi300733d] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The DNA cytosine deaminase APOBEC3G (A3G) is capable of blocking retrovirus replication by editing viral cDNA and impairing reverse transcription. However, the biophysical details of this host-pathogen interaction are unclear. We applied atomic force microscopy (AFM) and hybrid DNA substrates to investigate properties of A3G bound to single-stranded DNA (ssDNA). Hybrid DNA substrates included ssDNA with 5' or 3' ends attached to DNA duplexes (tail-DNA) and gap-DNA substrates, in which ssDNA is flanked by two double-stranded fragments. We found that A3G binds with similar efficiency to the 5' and 3' substrates, suggesting that ssDNA polarity is not an important factor. Additionally, we observed that A3G binds the single-stranded region of the gap-DNA substrates with the same efficiency as tail-DNA. These results demonstrate that single-stranded DNA ends are not needed for A3G binding. The protein stoichiometry does not depend on the ssDNA substrate type, but the ssDNA length modulates the stoichiometry of A3G in the complex. We applied single-molecule high-speed AFM to directly visualize the dynamics of A3G in the complexes. We were able to visualize A3G sliding and protein association-dissociation events. During sliding, A3G translocated over a 69-nucleotide ssDNA segment in <1 s. Association-dissociation events were more complex, as dimeric A3G could dissociate from the template as a whole or undergo a two-step process with monomers capable of sequential dissociation. We conclude that A3G monomers, dimers, and higher-order oligomers can bind ssDNA substrates in a manner independent of strand polarity and availability of free ssDNA ends.
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Affiliation(s)
- Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
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30
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Guide to video recording of structure dynamics and dynamic processes of proteins by high-speed atomic force microscopy. Nat Protoc 2012; 7:1193-206. [DOI: 10.1038/nprot.2012.047] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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