51
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Kilic Z, Sgouralis I, Pressé S. Generalizing HMMs to Continuous Time for Fast Kinetics: Hidden Markov Jump Processes. Biophys J 2021; 120:409-423. [PMID: 33421415 PMCID: PMC7896036 DOI: 10.1016/j.bpj.2020.12.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/25/2020] [Accepted: 12/30/2020] [Indexed: 12/18/2022] Open
Abstract
The hidden Markov model (HMM) is a framework for time series analysis widely applied to single-molecule experiments. Although initially developed for applications outside the natural sciences, the HMM has traditionally been used to interpret signals generated by physical systems, such as single molecules, evolving in a discrete state space observed at discrete time levels dictated by the data acquisition rate. Within the HMM framework, transitions between states are modeled as occurring at the end of each data acquisition period and are described using transition probabilities. Yet, whereas measurements are often performed at discrete time levels in the natural sciences, physical systems evolve in continuous time according to transition rates. It then follows that the modeling assumptions underlying the HMM are justified if the transition rates of a physical process from state to state are small as compared to the data acquisition rate. In other words, HMMs apply to slow kinetics. The problem is, because the transition rates are unknown in principle, it is unclear, a priori, whether the HMM applies to a particular system. For this reason, we must generalize HMMs for physical systems, such as single molecules, because these switch between discrete states in "continuous time". We do so by exploiting recent mathematical tools developed in the context of inferring Markov jump processes and propose the hidden Markov jump process. We explicitly show in what limit the hidden Markov jump process reduces to the HMM. Resolving the discrete time discrepancy of the HMM has clear implications: we no longer need to assume that processes, such as molecular events, must occur on timescales slower than data acquisition and can learn transition rates even if these are on the same timescale or otherwise exceed data acquisition rates.
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Affiliation(s)
- Zeliha Kilic
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, Arizona
| | - Ioannis Sgouralis
- Department of Mathematics, University of Tennessee, Knoxville, Tennessee
| | - Steve Pressé
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, Arizona; School of Molecular Sciences, Arizona State University, Tempe, Arizona.
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52
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Li J, Zhai J, Wang Y, Yang W, Xie X. Dual functional luminescent nanoprobes for monitoring oxygen and chloride concentration changes in cells. Chem Commun (Camb) 2020; 56:14980-14983. [PMID: 33179655 DOI: 10.1039/d0cc06258h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A dual functional nanoprobe Pd-Q+@PDMS was proposed to simultaneously monitor Cl- and O2, leading to the determination of an average Cl- concentration of 85.7 ± 5.5 mM in lysosomes of HeLa cells. Mimicking ischemic conditions, the cells exhibited a luminescence change corresponding to a decreasing subcellular Cl- concentration.
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Affiliation(s)
- Jing Li
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
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53
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Krishnan Y, Zou J, Jani MS. Quantitative Imaging of Biochemistry in Situ and at the Nanoscale. ACS CENTRAL SCIENCE 2020; 6:1938-1954. [PMID: 33274271 PMCID: PMC7706076 DOI: 10.1021/acscentsci.0c01076] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Indexed: 05/12/2023]
Abstract
Biochemical reactions in eukaryotic cells occur in subcellular, membrane-bound compartments called organelles. Each kind of organelle is characterized by a unique lumenal chemical composition whose stringent regulation is vital to proper organelle function. Disruption of the lumenal ionic content of organelles is inextricably linked to disease. Despite their vital roles in cellular homeostasis, there are large gaps in our knowledge of organellar chemical composition largely from a lack of suitable probes. In this Outlook, we describe how, using organelle-targeted ratiometric probes, one can quantitatively image the lumenal chemical composition and biochemical activity inside organelles. We discuss how excellent fluorescent detection chemistries applied largely to the cytosol may be expanded to study organelles by chemical imaging at subcellular resolution in live cells. DNA-based reporters are a new and versatile platform to enable such approaches because the resultant probes have precise ratiometry and accurate subcellular targeting and are able to map multiple chemicals simultaneously. Quantitatively mapping lumenal ions and biochemical activity can drive the discovery of new biology and biomedical applications.
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Affiliation(s)
| | - Junyi Zou
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Grossman Institute of Neuroscience,
Quantitative Biology and Human Behavior, University of Chicago, Chicago, Illinois 60637, United States
| | - Maulik S. Jani
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Grossman Institute of Neuroscience,
Quantitative Biology and Human Behavior, University of Chicago, Chicago, Illinois 60637, United States
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54
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Single-Molecule FRET Detection of Sub-Nanometer Distance Changes in the Range below a 3-Nanometer Scale. BIOSENSORS-BASEL 2020; 10:bios10110168. [PMID: 33171642 PMCID: PMC7695202 DOI: 10.3390/bios10110168] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/24/2020] [Accepted: 11/04/2020] [Indexed: 11/16/2022]
Abstract
Single-molecule fluorescence energy transfer (FRET) detection has become a key technique to monitor intra- and intermolecular distance changes in biological processes. As the sensitive detection range of conventional FRET pairs is limited to 3-8 nm, complement probes are necessary for extending this typical working range. Here, we realized a single-molecule FRET assay for a short distance range of below 3 nm by using a Cy2-Cy7 pair having extremely small spectral overlap. Using two DNA duplexes with a small difference in the labeling position, we demonstrated that our assay can observe subtle changes at a short distance range. High sensitivity in the range of 1-3 nm and compatibility with the conventional FRET assay make this approach useful for understanding dynamics at a short distance.
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55
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Helmerich DA, Beliu G, Sauer M. Multiple-Labeled Antibodies Behave Like Single Emitters in Photoswitching Buffer. ACS NANO 2020; 14:12629-12641. [PMID: 32804475 DOI: 10.1021/acsnano.0c06099] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The degree of labeling (DOL) of antibodies has so far been optimized for high brightness and specific and efficient binding. The influence of the DOL on the blinking performance of antibodies used in direct stochastic optical reconstruction microscopy (dSTORM) has so far attained limited attention. Here, we investigated the spectroscopic characteristics of IgG antibodies labeled at DOLs of 1.1-8.3 with Alexa Fluor 647 (Al647) at the ensemble and single-molecule level. Multiple-Al647-labeled antibodies showed weak and strong quenching interactions in aqueous buffer but could all be used for dSTORM imaging with spatial resolutions of ∼20 nm independent of the DOL. Single-molecule fluorescence trajectories and photon antibunching experiments revealed that individual multiple-Al647-labeled antibodies show complex photophysics in aqueous buffer but behave as single emitters in photoswitching buffer independent of the DOL. We developed a model that explains the observed blinking of multiple-labeled antibodies and can be used for the development of improved fluorescent probes for dSTORM experiments.
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Affiliation(s)
- Dominic A Helmerich
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Gerti Beliu
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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56
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Tsuyama Y, Mawatari K. Concentration Determination at a Countable Molecular Level in Nanofluidics by Solvent-Enhanced Photothermal Optical Diffraction. Anal Chem 2020; 92:14366-14372. [DOI: 10.1021/acs.analchem.0c02024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Yoshiyuki Tsuyama
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Kazuma Mawatari
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan
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57
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Lapolla A, Godec A. Faster Uphill Relaxation in Thermodynamically Equidistant Temperature Quenches. PHYSICAL REVIEW LETTERS 2020; 125:110602. [PMID: 32975999 DOI: 10.1103/physrevlett.125.110602] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 06/13/2020] [Accepted: 08/10/2020] [Indexed: 05/29/2023]
Abstract
We uncover an unforeseen asymmetry in relaxation: for a pair of thermodynamically equidistant temperature quenches, one from a lower and the other from a higher temperature, the relaxation at the ambient temperature is faster in the case of the former. We demonstrate this finding on hand of two exactly solvable many-body systems relevant in the context of single-molecule and tracer-particle dynamics. We prove that near stable minima and for all quadratic energy landscapes it is a general phenomenon that also exists in a class of non-Markovian observables probed in single-molecule and particle-tracking experiments. The asymmetry is a general feature of reversible overdamped diffusive systems with smooth single-well potentials and occurs in multiwell landscapes when quenches disturb predominantly intrawell equilibria. Our findings may be relevant for the optimization of stochastic heat engines.
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Affiliation(s)
- Alessio Lapolla
- Mathematical bioPhysics group, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Aljaž Godec
- Mathematical bioPhysics group, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
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58
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Tuning the Baird aromatic triplet-state energy of cyclooctatetraene to maximize the self-healing mechanism in organic fluorophores. Proc Natl Acad Sci U S A 2020; 117:24305-24315. [PMID: 32913060 PMCID: PMC7533661 DOI: 10.1073/pnas.2006517117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Bright, photostable, and nontoxic fluorescent contrast agents are critical for biological imaging. "Self-healing" dyes, in which triplet states are intramolecularly quenched, enable fluorescence imaging by increasing fluorophore brightness and longevity, while simultaneously reducing the generation of reactive oxygen species that promote phototoxicity. Here, we systematically examine the self-healing mechanism in cyanine-class organic fluorophores spanning the visible spectrum. We show that the Baird aromatic triplet-state energy of cyclooctatetraene can be physically altered to achieve order of magnitude enhancements in fluorophore brightness and signal-to-noise ratio in both the presence and absence of oxygen. We leverage these advances to achieve direct measurements of large-scale conformational dynamics within single molecules at submillisecond resolution using wide-field illumination and camera-based detection methods. These findings demonstrate the capacity to image functionally relevant conformational processes in biological systems in the kilohertz regime at physiological oxygen concentrations and shed important light on the multivariate parameters critical to self-healing organic fluorophore design.
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59
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Udhayakumari D, Inbaraj V. A Review on Schiff Base Fluorescent Chemosensors for Cell Imaging Applications. J Fluoresc 2020; 30:1203-1223. [PMID: 32737660 DOI: 10.1007/s10895-020-02570-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/03/2020] [Indexed: 11/29/2022]
Abstract
Fluorescent determinations of analytes have proven to be a powerful method due to their simplicity, low cost, detection limit, rapid photoluminescence response, and applicability to bioimaging. Fluorescence imaging as a powerful tool for monitoring biomolecules within the living systems. Schiff base has been extensively used as strongly absorbing and colorful chromophores in the design of chemosensors. In recent years, Schiff base based fluorescent probes have been developed for the detection of various toxic analytes and imaging of various analytes in biological systems. This review gives an overview of the important fluorescent sensors which are based on Schiff base, their approaches for molecular recognition, and their potential application in bioimaging studies.
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Affiliation(s)
| | - V Inbaraj
- Department of Chemistry, Rajalakshmi Engineering College, Chennai, 602105, India
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60
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Fast three-color single-molecule FRET using statistical inference. Nat Commun 2020; 11:3336. [PMID: 32620782 PMCID: PMC7335206 DOI: 10.1038/s41467-020-17149-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 06/11/2020] [Indexed: 12/21/2022] Open
Abstract
We describe theory, experiments, and analyses of three-color Förster resonance energy transfer (FRET) spectroscopy for probing sub-millisecond conformational dynamics of protein folding and binding of disordered proteins. We devise a scheme that uses single continuous-wave laser excitation of the donor instead of alternating excitation of the donor and one of the acceptors. This scheme alleviates photophysical problems of acceptors such as rapid photobleaching, which is crucial for high time resolution experiments with elevated illumination intensity. Our method exploits the molecular species with one of the acceptors absent or photobleached, from which two-color FRET data is collected in the same experiment. We show that three FRET efficiencies and kinetic parameters can be determined without alternating excitation from a global maximum likelihood analysis of two-color and three-color photon trajectories. We implement co-parallelization of CPU-GPU processing, which leads to a significant reduction of the likelihood calculation time for efficient parameter determination.
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61
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Farka Z, Mickert MJ, Pastucha M, Mikušová Z, Skládal P, Gorris HH. Fortschritte in der optischen Einzelmoleküldetektion: Auf dem Weg zu höchstempfindlichen Bioaffinitätsassays. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201913924] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Zdeněk Farka
- CEITEC – Central European Institute of TechnologyMasaryk University 625 00 Brno Czech Republic
| | - Matthias J. Mickert
- Institut für Analytische Chemie, Chemo- und BiosensorikUniversität Regensburg Universitätsstraße 31 93040 Regensburg Deutschland
| | - Matěj Pastucha
- CEITEC – Central European Institute of TechnologyMasaryk University 625 00 Brno Czech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University 625 00 Brno Czech Republic
| | - Zuzana Mikušová
- CEITEC – Central European Institute of TechnologyMasaryk University 625 00 Brno Czech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University 625 00 Brno Czech Republic
| | - Petr Skládal
- CEITEC – Central European Institute of TechnologyMasaryk University 625 00 Brno Czech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University 625 00 Brno Czech Republic
| | - Hans H. Gorris
- Institut für Analytische Chemie, Chemo- und BiosensorikUniversität Regensburg Universitätsstraße 31 93040 Regensburg Deutschland
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62
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Farka Z, Mickert MJ, Pastucha M, Mikušová Z, Skládal P, Gorris HH. Advances in Optical Single-Molecule Detection: En Route to Supersensitive Bioaffinity Assays. Angew Chem Int Ed Engl 2020; 59:10746-10773. [PMID: 31869502 PMCID: PMC7318240 DOI: 10.1002/anie.201913924] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/20/2019] [Indexed: 12/11/2022]
Abstract
The ability to detect low concentrations of analytes and in particular low-abundance biomarkers is of fundamental importance, e.g., for early-stage disease diagnosis. The prospect of reaching the ultimate limit of detection has driven the development of single-molecule bioaffinity assays. While many review articles have highlighted the potentials of single-molecule technologies for analytical and diagnostic applications, these technologies are not as widespread in real-world applications as one should expect. This Review provides a theoretical background on single-molecule-or better digital-assays to critically assess their potential compared to traditional analog assays. Selected examples from the literature include bioaffinity assays for the detection of biomolecules such as proteins, nucleic acids, and viruses. The structure of the Review highlights the versatility of optical single-molecule labeling techniques, including enzymatic amplification, molecular labels, and innovative nanomaterials.
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Affiliation(s)
- Zdeněk Farka
- CEITEC – Central European Institute of TechnologyMasaryk University625 00BrnoCzech Republic
| | - Matthias J. Mickert
- Institute of Analytical Chemistry, Chemo- and BiosensorsUniversity of RegensburgUniversitätsstraße 3193040RegensburgGermany
| | - Matěj Pastucha
- CEITEC – Central European Institute of TechnologyMasaryk University625 00BrnoCzech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University625 00BrnoCzech Republic
| | - Zuzana Mikušová
- CEITEC – Central European Institute of TechnologyMasaryk University625 00BrnoCzech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University625 00BrnoCzech Republic
| | - Petr Skládal
- CEITEC – Central European Institute of TechnologyMasaryk University625 00BrnoCzech Republic
- Department of BiochemistryFaculty of ScienceMasaryk University625 00BrnoCzech Republic
| | - Hans H. Gorris
- Institute of Analytical Chemistry, Chemo- and BiosensorsUniversity of RegensburgUniversitätsstraße 3193040RegensburgGermany
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63
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Yin S, Tien M, Yang H. Prior-Apprised Unsupervised Learning of Subpixel Curvilinear Features in Low Signal/Noise Images. Biophys J 2020; 118:2458-2469. [PMID: 32359407 PMCID: PMC7231927 DOI: 10.1016/j.bpj.2020.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/07/2020] [Accepted: 04/09/2020] [Indexed: 11/16/2022] Open
Abstract
Many biophysical problems involve molecular and nanoscale targets moving next to a curvilinear track, e.g., a cytosolic cargo transported by motor proteins moving along a microtubule. For this type of problem, fluorescence imaging is usually the primary tool of choice. There is, however, an ∼20-fold mismatch between target-localization precision and track-imaging resolution such that questions requiring high-fidelity definition of the target's track remain inaccessible. On the other hand, if the contextual image of the tracks can be refined to a level comparable to that of the target, many intuitive yet mechanistically important issues can begin to be addressed. This work demonstrates that it is possible to statistically infer, to subpixel precision, curvilinear features in a low signal/noise image. This is achieved by a framework that consists of three stages: the Hessian-based feature enhancement, the subimage feature sampling and registration, and the statistical learning of the underlying curvilinear structure using a new, to our knowledge, method developed here for inferring the principal curves. In each stage, the descriptive prior information that the features come from curvilinear elements is explicitly taken into account. It is fully automated without user supervision, which is distinctly different from approaches that require user seeding or well-defined training data sets. Computer simulations of realistic images are used to investigate the performance of the framework and its implementation. The characterization results suggest that curvilinear features are refined to the same order of precision as that of the target and that the bootstrap confidence intervals from the analysis allow an estimate for the statistical bounds of the simulated "true" curve. Also shown are analyses of experimental images from three different microscopy modalities: two-photon laser-scanning microscopy, epifluorescence microscopy, and total internal reflection fluorescence microscopy. The practical application of this prior-apprised unsupervised learning framework as well as its potential outlook are discussed.
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Affiliation(s)
- Shuhui Yin
- Department of Chemistry, Princeton University, Princeton, New Jersey
| | - Ming Tien
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania
| | - Haw Yang
- Department of Chemistry, Princeton University, Princeton, New Jersey.
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64
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A 6-nm ultra-photostable DNA FluoroCube for fluorescence imaging. Nat Methods 2020; 17:437-441. [PMID: 32203385 PMCID: PMC7138518 DOI: 10.1038/s41592-020-0782-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 02/12/2020] [Indexed: 12/17/2022]
Abstract
Photobleaching limits extended imaging of fluorescent biological samples. Here, we developed DNA based “FluoroCubes” that are similar in size to the green fluorescent protein (GFP), have single-point attachment to proteins, have a ~54-fold higher photobleaching lifetime and emit ~43-fold more photons than single organic dyes. We demonstrate that DNA FluoroCubes provide outstanding tools for single-molecule imaging, allowing the tracking of single motor proteins for >800 steps with nanometer precision.
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65
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Recent advances in bioimaging with high-speed atomic force microscopy. Biophys Rev 2020; 12:363-369. [PMID: 32172451 DOI: 10.1007/s12551-020-00670-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 02/26/2020] [Indexed: 01/13/2023] Open
Abstract
Among various microscopic techniques for characterizing protein structures and functions, high-speed atomic force microscopy (HS-AFM) is a unique technique in that it allows direct visualization of structural changes and molecular interactions of proteins without any labeling in a liquid environment. Since the development of the HS-AFM was first reported in 2001, it has been applied to analyze the dynamics of various types of proteins, including motor proteins, membrane proteins, DNA-binding proteins, amyloid proteins, and artificial proteins. This method has now become a versatile tool indispensable for biophysical research. This short review summarizes some bioimaging applications of HS-AFM reported in the last few years and novel applications of HS-AFM utilizing the unique ability of AFM to gain mechanical properties of samples in addition to structural information.
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66
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Kang Y, Cheon NY, Cha J, Kim A, Kim HI, Lee L, Kim KO, Jo K, Lee JY. High-throughput single-molecule imaging system using nanofabricated trenches and fluorescent DNA-binding proteins. Biotechnol Bioeng 2020; 117:1640-1648. [PMID: 32162675 DOI: 10.1002/bit.27331] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/02/2020] [Accepted: 03/11/2020] [Indexed: 12/18/2022]
Abstract
DNA curtain is a high-throughput system, integrating a lipid bilayer, fluorescence imaging, and microfluidics to probe protein-DNA interactions in real-time and has provided in-depth understanding of DNA metabolism. Especially, the microfluidic platform of a DNA curtain is highly suitable for a biochip. In the DNA curtain, DNA molecules are aligned along chromium nanobarriers, which are fabricated on a slide surface, and visualized using an intercalating dye, YOYO-1. Although the chromium barriers confer precise geometric alignment of DNA, reuse of the slides is limited by wear of the barriers during cleaning. YOYO-1 is rapidly photobleached and causes photocleavage of DNA under continuous laser illumination, restricting DNA observation to a brief time window. To address these challenges, we developed a new nanopatterned slide, upon which carved nanotrenches serve as diffusion barriers. The nanotrenches were robust under harsh cleaning conditions, facilitating the maintenance of surface cleanliness that is essential to slide reuse. We also stained DNA with a fluorescent protein with a DNA-binding motif, fluorescent protein-DNA binding peptide (FP-DBP). FP-DBP was slowly photobleached and did not cause DNA photocleavage. This new DNA curtain system enables a more stable and repeatable investigation of real-time protein-DNA interactions and will serve as a good platform for lab-on-a-chip.
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Affiliation(s)
- Yujin Kang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Na Young Cheon
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jongjin Cha
- Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea
| | - Ayoung Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyung-Il Kim
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Luda Lee
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Kang O Kim
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Kyubong Jo
- Department of Chemistry and Integrated Biotechnology, Sogang University, Seoul, Republic of Korea
| | - Ja Yil Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.,Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
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67
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Oh M, Jayasooriya V, Woo SO, Nawarathna D, Choi Y. Selective Manipulation of Biomolecules with Insulator-Based Dielectrophoretic Tweezers. ACS APPLIED NANO MATERIALS 2020; 3:797-805. [PMID: 32587952 PMCID: PMC7316190 DOI: 10.1021/acsanm.9b02302] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Insulator-based dielectrophoretic (iDEP) trapping, separating, and concentrating nanoscale objects is carried out using a non-metal, unbiased, mobile tip acing as a tweezers. The spatial control and manipulation of fluorescently-labeled polystyrene particles and DNA were performed to demonstrate the feasibility of the iDEP tweezers. Frequency-dependent iDEP tweezers' strength and polarity were quantitatively determined using two theoretical approaches to DNA, which resulted in a factor of 2 ~ 40 differences between them. In either approach, the strength of iDEP was at least 4-order of magnitude stronger than the thermal force, indicating iDEP was a dominant force for trapping, holding, and separating DNA. The trapping strength and volume of the iDEP tweezers were also determined, which further supports direct capture and manipulation of DNA at the tip end.
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Affiliation(s)
- Myungkeun Oh
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Vidura Jayasooriya
- Department of Electrical and Computer Engineering, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Sung Oh Woo
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Dharmakeerthi Nawarathna
- Department of Electrical and Computer Engineering, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Yongki Choi
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, USA
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA
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68
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Birol M, Melo AM. Untangling the Conformational Polymorphism of Disordered Proteins Associated With Neurodegeneration at the Single-Molecule Level. Front Mol Neurosci 2020; 12:309. [PMID: 31998071 PMCID: PMC6965022 DOI: 10.3389/fnmol.2019.00309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/29/2019] [Indexed: 12/15/2022] Open
Abstract
A large fraction of the human genome encodes intrinsically disordered proteins/regions (IDPs/IDRs) that are involved in diverse cellular functions/regulation and dysfunctions. Moreover, several neurodegenerative disorders are associated with the pathological self-assembly of neuronal IDPs, including tau [Alzheimer's disease (AD)], α-synuclein [Parkinson's disease (PD)], and huntingtin exon 1 [Huntington's disease (HD)]. Therefore, there is an urgent and emerging clinical interest in understanding the physical and structural features of their functional and disease states. However, their biophysical characterization is inherently challenging by traditional ensemble techniques. First, unlike globular proteins, IDPs lack stable secondary/tertiary structures under physiological conditions and may interact with multiple and distinct biological partners, subsequently folding differentially, thus contributing to the conformational polymorphism. Second, amyloidogenic IDPs display a high aggregation propensity, undergoing complex heterogeneous self-assembly mechanisms. In this review article, we discuss the advantages of employing cutting-edge single-molecule fluorescence (SMF) techniques to characterize the conformational ensemble of three selected neuronal IDPs (huntingtin exon 1, tau, and α-synuclein). Specifically, we survey the versatility of these powerful approaches to describe their monomeric conformational ensemble under functional and aggregation-prone conditions, and binding to biological partners. Together, the information gained from these studies provides unique insights into the role of gain or loss of function of these disordered proteins in neurodegeneration, which may assist the development of new therapeutic molecules to prevent and treat these devastating human disorders.
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Affiliation(s)
- Melissa Birol
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Ana M Melo
- Centro de Química-Física Molecular- IN and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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69
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Licatalosi DD, Ye X, Jankowsky E. Approaches for measuring the dynamics of RNA-protein interactions. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1565. [PMID: 31429211 PMCID: PMC7006490 DOI: 10.1002/wrna.1565] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/20/2019] [Accepted: 07/25/2019] [Indexed: 12/17/2022]
Abstract
RNA-protein interactions are pivotal for the regulation of gene expression from bacteria to human. RNA-protein interactions are dynamic; they change over biologically relevant timescales. Understanding the regulation of gene expression at the RNA level therefore requires knowledge of the dynamics of RNA-protein interactions. Here, we discuss the main experimental approaches to measure dynamic aspects of RNA-protein interactions. We cover techniques that assess dynamics of cellular RNA-protein interactions that accompany biological processes over timescales of hours or longer and techniques measuring the kinetic dynamics of RNA-protein interactions in vitro. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Evolution and Genomics > Ribonomics.
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Affiliation(s)
- Donny D Licatalosi
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Xuan Ye
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Eckhard Jankowsky
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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70
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de Souza VP, Santos FS, Rodembusch FS, Braga CB, Ornelas C, Pilli RA, Russowsky D. Hybrid 3,4-dihydropyrimidin-2-(thi)ones as dual-functional bioactive molecules: fluorescent probes and cytotoxic agents to cancer cells. NEW J CHEM 2020. [DOI: 10.1039/d0nj01368d] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A series of new hybrid fluorescent Biginelli compounds, including a Monastrol derivative, were designed and synthesized with good yields.
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Affiliation(s)
- Vanessa P. de Souza
- Laboratório de Sínteses Orgânicas
- Instituto de Química
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
| | - Fabiano S. Santos
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada
- Instituto de Química
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
| | - Fabiano S. Rodembusch
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada
- Instituto de Química
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
| | - Carolyne B. Braga
- Instituto de Química
- Universidade Estadual de Campinas
- Cidade Universitária Zeferino Vaz
- Campinas
- Brazil
| | - Catia Ornelas
- Instituto de Química
- Universidade Estadual de Campinas
- Cidade Universitária Zeferino Vaz
- Campinas
- Brazil
| | - Ronaldo A. Pilli
- Instituto de Química
- Universidade Estadual de Campinas
- Cidade Universitária Zeferino Vaz
- Campinas
- Brazil
| | - Dennis Russowsky
- Laboratório de Sínteses Orgânicas
- Instituto de Química
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
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71
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Zhao X, Guo S, Lu C, Chen J, Le S, Fu H, Yan J. Single-molecule manipulation quantification of site-specific DNA binding. Curr Opin Chem Biol 2019; 53:106-117. [DOI: 10.1016/j.cbpa.2019.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/24/2019] [Accepted: 08/24/2019] [Indexed: 10/25/2022]
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72
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Ma G, Hu C, Li S, Gao X, Li H, Hu X. Simultaneous, hybrid single-molecule method by optical tweezers and fluorescence. NANOTECHNOLOGY AND PRECISION ENGINEERING 2019. [DOI: 10.1016/j.npe.2019.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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73
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Platnich CM, Hariri AA, Sleiman HF, Cosa G. Advancing Wireframe DNA Nanostructures Using Single-Molecule Fluorescence Microscopy Techniques. Acc Chem Res 2019; 52:3199-3210. [PMID: 31675207 DOI: 10.1021/acs.accounts.9b00424] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA nanotechnology relies on the molecular recognition properties of DNA to produce complex architectures through self-assembly. The resulting DNA nanostructures allow scientists to organize functional materials at the nanoscale and have therefore found applications in many domains of materials science over the past several years. These scaffolds have been used to position proteins, nanoparticles, carbon nanotubes, and other nanomaterials with high spatial resolution. In addition to their remarkable performance as frameworks for other species, DNA constructs also possess interesting dynamic properties, which have led to their use in logic circuits, drug delivery vehicles, and molecular walkers. Although DNA nanostructures have become increasingly complex, the development of tools to study them has lagged. Currently, gel electrophoresis, dynamic light scattering, and ensemble fluorescence measurements are widely used to characterize DNA-based assemblies. Unfortunately, ensemble averaging in these methods obscures malformed structures and may mask properties associated with structure, length, and shape in polydisperse samples. While atomic force microscopy allows for the determination of morphology at the single-molecule level, this technique cannot typically be used to assess the dynamic properties of these constructs. To analyze the function of DNA-based devices such as molecular motors and reconfigurable nanostructures in real time, new single-molecule techniques are required. This Account details the work from our laboratories toward developing single-molecule fluorescence (SMF) methodologies for the structural and dynamic characterization of wireframe DNA nanostructures, one at a time. The methods described herein provide us with two separate yet related sets of information: First, we can statically examine the nanostructures one by one to assess their robustness, structural fidelity, and morphology. This is primarily done using two-color stepwise photobleaching, wherein we can examine the subunit stoichiometry of our assemblies before and after various perturbations to the structures. For example, we can introduce length mismatches to cause the nanotube to bend or perform strand displacement reactions to generate single-stranded, flexible analogues of our materials. Second, due to the unmatched spatiotemporal resolution of SMF techniques, we can study the dynamic character of these assemblies by implementing structural changes to the nanotube and monitoring them in real time. With this structural and dynamic information in hand, our groups have additionally developed new tools for the improved construction of DNA nanotubes, inspired by solid-phase DNA synthesis. By assembling the nanotubes in a stepwise manner, highly monodisperse nanostructures of any desired length can be made without a template strand. In this way, unique building blocks can also be added sequence-specifically, allowing for the production of user-defined scaffolds to organize nanoscale materials in three dimensions. This method, in combination with our imaging and analysis protocols, may be extended to assemble and inspect other supramolecular constructs in a controlled manner. Overall, by combining synthesis, characterization, and analysis, these single-molecule techniques hold the potential to advance the study of DNA nanostructures and dynamic DNA-based devices.
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Affiliation(s)
- Casey M. Platnich
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Amani A. Hariri
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Hanadi F. Sleiman
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Gonzalo Cosa
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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Heiss G, Ploetz E, Voith von Voithenberg L, Viswanathan R, Glaser S, Schluesche P, Madhira S, Meisterernst M, Auble DT, Lamb DC. Conformational changes and catalytic inefficiency associated with Mot1-mediated TBP-DNA dissociation. Nucleic Acids Res 2019; 47:2793-2806. [PMID: 30649478 PMCID: PMC6451094 DOI: 10.1093/nar/gky1322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 12/21/2018] [Accepted: 01/07/2019] [Indexed: 11/12/2022] Open
Abstract
The TATA-box Binding Protein (TBP) plays a central role in regulating gene expression and is the first step in the process of pre-initiation complex (PIC) formation on promoter DNA. The lifetime of TBP at the promoter site is controlled by several cofactors including the Modifier of transcription 1 (Mot1), an essential TBP-associated ATPase. Based on ensemble measurements, Mot1 can use adenosine triphosphate (ATP) hydrolysis to displace TBP from DNA and various models for how this activity is coupled to transcriptional regulation have been proposed. However, the underlying molecular mechanism of Mot1 action is not well understood. In this work, the interaction of Mot1 with the DNA/TBP complex was investigated by single-pair Förster resonance energy transfer (spFRET). Upon Mot1 binding to the DNA/TBP complex, a transition in the DNA/TBP conformation was observed. Hydrolysis of ATP by Mot1 led to a conformational change but was not sufficient to efficiently disrupt the complex. SpFRET measurements of dual-labeled DNA suggest that Mot1's ATPase activity primes incorrectly oriented TBP for dissociation from DNA and additional Mot1 in solution is necessary for TBP unbinding. These findings provide a framework for understanding how the efficiency of Mot1's catalytic activity is tuned to establish a dynamic pool of TBP without interfering with stable and functional TBP-containing complexes.
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Affiliation(s)
- Gregor Heiss
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Evelyn Ploetz
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Lena Voith von Voithenberg
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Ramya Viswanathan
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Samson Glaser
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Peter Schluesche
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Sushi Madhira
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Michael Meisterernst
- Institut für Molekulare Tumorbiologie, Westfälische Wilhelms-Universität, Münster 48149, Germany
| | - David T Auble
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Don C Lamb
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
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75
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Kandula HN, Jee AY, Granick S. Robustness of FCS (Fluorescence Correlation Spectroscopy) with Quenchers Present. J Phys Chem A 2019; 123:10184-10189. [PMID: 31702916 DOI: 10.1021/acs.jpca.9b08273] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inspired by recent publications doubtful of the FCS technique, we scrutinize how irreversible ("static") and reversible ("dynamic") quenching can influence the interpretation of such data. Textbook presentations often emphasize only how to analyze data in extremes, the absence of quenching or the presence of substantial quenching. Here, we consider intermediate cases where the assessment of photophysics (static quenching, blinking-like triplet-state relaxation) influence on autocorrelation curves can be delicate if dye-labeled objects diffuse on comparably rapid time scales. We used the amino acid, tryptophan, as the quencher. As our example of small-molecule dye that diffuses rapidly, we mix the quencher with the fluorescence dye, Alexa 488. The translational diffusion coefficient, inferred from fit to the standard one-component Fickian diffusion model, speeds up without the loss of quality of fit, but quenching is reflected in the fact that the data become exceptionally noisy. This reflects the bidisperse population of quenched and unquenched dyes when the time scales overlap between the processes of translational diffusion, quenching, and blinking. As our example of the large-molecule dye-labeled object that diffuses relatively slowly, we mixed the quencher with dye-labeled BSA, bovine serum albumin. Diffusion, static quenching, and blinking time scales are now separated. In spite of quenching contribution to the autocorrelation function when the delay time is relatively short, the inferred translational diffusion coefficient now depends weakly on the presence of a quencher. We conclude that when the diffusing molecule is substantially slower to diffuse than the time scale of photophysical processes of the fluorescent dye to which it is attached, the influence of quenching is self-evident and the FCS autocorrelation curves give an appropriate diffusion coefficient if correct fitting functions are chosen in the analysis.
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Affiliation(s)
- Hima Nagamanasa Kandula
- Center for Soft and Living Matter , Institute for Basic Science (IBS) , Ulsan 44919 , South Korea
| | - Ah-Young Jee
- Center for Soft and Living Matter , Institute for Basic Science (IBS) , Ulsan 44919 , South Korea
| | - Steve Granick
- Center for Soft and Living Matter , Institute for Basic Science (IBS) , Ulsan 44919 , South Korea.,Department of Chemistry , Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919 , South Korea
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76
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Schärfen L, Schlierf M. Real-time monitoring of protein-induced DNA conformational changes using single-molecule FRET. Methods 2019; 169:11-20. [DOI: 10.1016/j.ymeth.2019.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 12/21/2018] [Accepted: 02/11/2019] [Indexed: 12/11/2022] Open
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77
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Krainer G, Keller S, Schlierf M. Structural dynamics of membrane-protein folding from single-molecule FRET. Curr Opin Struct Biol 2019; 58:124-137. [DOI: 10.1016/j.sbi.2019.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/27/2019] [Indexed: 12/15/2022]
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78
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Teng IT, Bu X, Chung I. Conjugation of Fab' Fragments with Fluorescent Dyes for Single-Molecule Tracking On Live Cells. Bio Protoc 2019; 9:e3375. [PMID: 33654871 DOI: 10.21769/bioprotoc.3375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 12/28/2022] Open
Abstract
Our understanding of the regulation and functions of cell-surface proteins has progressed rapidly with the advent of advanced optical imaging techniques. In particular, single-molecule tracking (SMT) using bright fluorophores conjugated to antibodies and wide-field microscopy methods such as total internal reflection fluorescence microscopy have become valuable tools to discern how endogenous proteins control cell biology. Yet, some technical challenges remain; in SMT, these revolve around the characteristics of the labeling reagent. A good reagent should have neutrality (in terms of not affecting the target protein's functions), tagging specificity, and a bright fluorescence signal. In addition, a long shelf-life is desirable due to the time and monetary costs associated with reagent preparation. Semiconductor-based quantum dots (Qdots) or Janelia Fluor (JF) dyes are bright and photostable, and are thus excellent candidates for SMT tagging. Neutral, high-affinity antibodies can selectively bind to target proteins. However, the bivalency of antibodies can cause simultaneous binding to two proteins, and this bridging effect can alter protein functions and behaviors. Bivalency can be avoided using monovalent Fab fragments generated by enzymatic digestion of neutral antibodies. However, conjugation of a Fab with a dye using the chemical cross-linking agent SMCC (succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate) requires reduction of the interchain disulfide bond within the Fab fragment, which can decrease the structural stability of the Fab and weaken its antigen-binding capability. To overcome this problem, we perform limited reduction of F(ab')2 to generate Fab' fragments using a weak reducer, cysteamine, which yields free sulfhydryl groups in the hinge region, while the interchain disulfide bond in Fab' is intact. Here, we describe a method that generates Fab' with high yield from two isoforms of IgG and conjugates the Fab' fragments with Qdots. This conjugation scheme can be applied easily to other types of dyes with similar chemical characteristics.
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Affiliation(s)
- I-Ting Teng
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Xiangning Bu
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Inhee Chung
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
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79
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Cui TJ, Joo C. Facilitated diffusion of Argonaute-mediated target search. RNA Biol 2019; 16:1093-1107. [PMID: 31068066 PMCID: PMC6693542 DOI: 10.1080/15476286.2019.1616353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 04/29/2019] [Accepted: 05/01/2019] [Indexed: 10/26/2022] Open
Abstract
Argonaute (Ago) proteins are of key importance in many cellular processes. In eukaryotes, Ago can induce translational repression followed by deadenylation and degradation of mRNA molecules through base pairing of microRNAs (miRNAs) with a complementary target on a mRNA sequence. In bacteria, Ago eliminates foreign DNA through base pairing of siDNA (small interfering DNA) with a target on a DNA sequence. Effective targeting activities of Ago require fast recognition of the cognate target sequence among numerous off-target sites. Other target search proteins such as transcription factors (TFs) are known to rely on facilitated diffusion for this goal, but it is undetermined to what extent these small nucleic acid-guided proteins utilize this mechanism. Here, we review recent single-molecule studies on Ago target search. We discuss the consequences of the recent findings on the search mechanism. Furthermore, we discuss the open standing research questions that need to be addressed for a complete picture of facilitated target search by small nucleic acids.
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Affiliation(s)
- Tao Ju Cui
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, Delft, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, Delft, The Netherlands
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80
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Desai VP, Frank F, Lee A, Righini M, Lancaster L, Noller HF, Tinoco I, Bustamante C. Co-temporal Force and Fluorescence Measurements Reveal a Ribosomal Gear Shift Mechanism of Translation Regulation by Structured mRNAs. Mol Cell 2019; 75:1007-1019.e5. [PMID: 31471187 DOI: 10.1016/j.molcel.2019.07.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/12/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022]
Abstract
The movement of ribosomes on mRNA is often interrupted by secondary structures that present mechanical barriers and play a central role in translation regulation. We investigate how ribosomes couple their internal conformational changes with the activity of translocation factor EF-G to unwind mRNA secondary structures using high-resolution optical tweezers with single-molecule fluorescence capability. We find that hairpin opening occurs during EF-G-catalyzed translocation and is driven by the forward rotation of the small subunit head. Modulating the magnitude of the hairpin barrier by force shows that ribosomes respond to strong barriers by shifting their operation to an alternative 7-fold-slower kinetic pathway prior to translocation. Shifting into a slow gear results from an allosteric switch in the ribosome that may allow it to exploit thermal fluctuations to overcome mechanical barriers. Finally, we observe that ribosomes occasionally open the hairpin in two successive sub-codon steps, revealing a previously unobserved translocation intermediate.
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Affiliation(s)
- Varsha P Desai
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Filipp Frank
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Antony Lee
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Maurizio Righini
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Laura Lancaster
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Harry F Noller
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Ignacio Tinoco
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Carlos Bustamante
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Kavli Energy Nanoscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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81
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Duchi D, Gryte K, Robb NC, Morichaud Z, Sheppard C, Brodolin K, Wigneshweraraj S, Kapanidis AN. Conformational heterogeneity and bubble dynamics in single bacterial transcription initiation complexes. Nucleic Acids Res 2019; 46:677-688. [PMID: 29177430 PMCID: PMC5778504 DOI: 10.1093/nar/gkx1146] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 10/31/2017] [Indexed: 12/16/2022] Open
Abstract
Transcription initiation is a major step in gene regulation for all organisms. In bacteria, the promoter DNA is first recognized by RNA polymerase (RNAP) to yield an initial closed complex. This complex subsequently undergoes conformational changes resulting in DNA strand separation to form a transcription bubble and an RNAP-promoter open complex; however, the series and sequence of conformational changes, and the factors that influence them are unclear. To address the conformational landscape and transitions in transcription initiation, we applied single-molecule Förster resonance energy transfer (smFRET) on immobilized Escherichia coli transcription open complexes. Our results revealed the existence of two stable states within RNAP–DNA complexes in which the promoter DNA appears to adopt closed and partially open conformations, and we observed large-scale transitions in which the transcription bubble fluctuated between open and closed states; these transitions, which occur roughly on the 0.1 s timescale, are distinct from the millisecond-timescale dynamics previously observed within diffusing open complexes. Mutational studies indicated that the σ70 region 3.2 of the RNAP significantly affected the bubble dynamics. Our results have implications for many steps of transcription initiation, and support a bend-load-open model for the sequence of transitions leading to bubble opening during open complex formation.
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Affiliation(s)
- Diego Duchi
- Gene Machines Group, Biological Physics Research Unit, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Kristofer Gryte
- Gene Machines Group, Biological Physics Research Unit, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Nicole C Robb
- Gene Machines Group, Biological Physics Research Unit, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Zakia Morichaud
- CNRS UMR 9004, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, 1919 route de Mende, 34293 Montpellier, France
| | - Carol Sheppard
- MRC Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Konstantin Brodolin
- CNRS UMR 9004, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, 1919 route de Mende, 34293 Montpellier, France
| | | | - Achillefs N Kapanidis
- Gene Machines Group, Biological Physics Research Unit, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
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82
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Song S, Wang H, Sun M, Tang J, Zheng B, Wang X, Tan YW. Reactive oxygen species-mediated BIN2 activity revealed by single-molecule analysis. THE NEW PHYTOLOGIST 2019; 223:692-704. [PMID: 30597572 DOI: 10.1111/nph.15669] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 12/21/2018] [Indexed: 05/28/2023]
Abstract
Much evidence has shown that reactive oxygen species (ROS) regulate several plant hormone signaling cascades, but little is known about the real-time kinetics and the underlying molecular mechanisms of the target proteins in the brassinosteroid (BR) signaling pathway. In this study, we used single-molecule techniques to investigate the true signaling timescales of the major BR signaling components BRI1-EMS-SUPPRESSOR 1 (BES1) and BRASSINOSTEROID INSENSITIVE 2 (BIN2) of Arabidopsis thaliana. The rate constants of BIN2 associating with ATP and phosphorylating BES1 were determined to be 0.7 ± 0.4 mM-1 s-1 and 2.3 ± 1.4 s-1 , respectively. Interestingly, we found that the interaction of BIN2 and BES1 was oxygen-dependent, and oxygen can directly modify BIN2. The activity of BIN2 was switched on via modification of specific cysteine (Cys) residues, including C59, C95, C99 and C162. The mutation of these Cys residues inhibited the BR signaling outputs. These findings demonstrate the power of using single-molecule techniques to study the dynamic interactions of signaling components, which is difficult to be discovered by conventional physiological and biochemical methods.
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Affiliation(s)
- Song Song
- State Key Laboratory of Surface Physics, Collaborative Innovation Center for Genetics and Development, Department of Physics, Fudan University, Shanghai, 200433, China
| | - Haijiao Wang
- Center of Integrative Biology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Mengyuan Sun
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Jie Tang
- Center of Integrative Biology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Binglian Zheng
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Xuelu Wang
- Center of Integrative Biology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yan-Wen Tan
- State Key Laboratory of Surface Physics, Collaborative Innovation Center for Genetics and Development, Department of Physics, Fudan University, Shanghai, 200433, China
- Multiscale Research Institute for Complex Systems, Fudan University, Shanghai, 200438, China
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83
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Hu J, Liu MH, Zhang CY. Construction of Tetrahedral DNA-Quantum Dot Nanostructure with the Integration of Multistep Förster Resonance Energy Transfer for Multiplex Enzymes Assay. ACS NANO 2019; 13:7191-7201. [PMID: 31180625 DOI: 10.1021/acsnano.9b02679] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Three-dimensional (3D) DNA scaffolds with well-defined structure and high controllability hold promising potentials for biosensing and drug delivery. However, most of 3D DNA scaffolds can detect only a single type of molecule with the involvement of complex logic operations. Herein, we develop a 3D DNA nanostructure with the capability of multiplexed detection by exploiting a multistep Förster resonance energy transfer (FRET). The tetrahedron-structured DNA is constructed by four oligonucleotide strands and is subsequently conjugated to a streptavidin-coated quantum dot (QD) to obtain a QD-Cy3-Texas Red-Cy5 tetrahedron DNA. This QD-Cy3-Texas Red-Cy5 tetrahedral DNA nanostructure has well-defined dye-to-dye spacing and high controllability for energy transfer between intermediary acceptors and terminal acceptors, enabling the generation of multistep FRET between the QD and three dyes (i.e., Cy3, Texas Red, and Cy5) for simultaneous detection of multiple endonucleases and methyltransferases even in complex biological samples as well as the screening of multiple enzyme inhibitors.
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Affiliation(s)
- Juan Hu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , China
| | - Ming-Hao Liu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , China
| | - Chun-Yang Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , China
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84
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Abstract
While belonging to the nanoscale, protein machines are so complex that tracing even a small fraction of their cycle requires weeks of calculations on supercomputers. Surprisingly, many aspects of their operation can be however already reproduced by using very simple mechanical models of elastic networks. The analysis suggests that, similar to other self-organized complex systems, functional collective dynamics in such proteins is effectively reduced to a low-dimensional attractive manifold.
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Affiliation(s)
- Holger Flechsig
- 1 Nano Life Science Institute (WPI-NanoLSI), Kanazawa University , Kakuma-machi, 920-1192 Kanazawa , Japan
| | - Alexander S Mikhailov
- 1 Nano Life Science Institute (WPI-NanoLSI), Kanazawa University , Kakuma-machi, 920-1192 Kanazawa , Japan.,2 Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society , Faradayweg 4-6, 14195 Berlin , Germany
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85
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Yokota H. Fluorescence microscopy for visualizing single-molecule protein dynamics. Biochim Biophys Acta Gen Subj 2019; 1864:129362. [PMID: 31078674 DOI: 10.1016/j.bbagen.2019.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/26/2019] [Accepted: 05/07/2019] [Indexed: 01/06/2023]
Abstract
BACKGROUND Single-molecule fluorescence imaging (smFI) has evolved into a valuable method used in biophysical and biochemical studies as it can observe the real-time behavior of individual protein molecules, enabling understanding of their detailed dynamic features. smFI is also closely related to other state-of-the-art microscopic methods, optics, and nanomaterials in that smFI and these technologies have developed synergistically. SCOPE OF REVIEW This paper provides an overview of the recently developed single-molecule fluorescence microscopy methods, focusing on critical techniques employed in higher-precision measurements in vitro and fluorescent nanodiamond, an emerging promising fluorophore that will improve single-molecule fluorescence microscopy. MAJOR CONCLUSIONS smFI will continue to improve regarding the photostability of fluorophores and will develop via combination with other techniques based on nanofabrication, single-molecule manipulation, and so on. GENERAL SIGNIFICANCE Quantitative, high-resolution single-molecule studies will help establish an understanding of protein dynamics and complex biomolecular systems.
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Affiliation(s)
- Hiroaki Yokota
- Biophotonics Laboratory, Graduate School for the Creation of New Photonics Industries, Kurematsu-cho, Nishi-ku, Hamamatsu, Shizuoka 431-1202, Japan.
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86
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Single-molecule fluorescence studies of intrinsically disordered proteins and liquid phase separation. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:980-987. [PMID: 31054969 DOI: 10.1016/j.bbapap.2019.04.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 01/09/2023]
Abstract
Intrinsically disordered proteins (IDPs) are ubiquitous in proteomes and serve in a range of cellular functions including signaling, regulation, transport and enzyme function. IDP misfunction and aggregation are also associated with several diseases including neurodegenerative diseases and cancer. During the past decade, single-molecule methods have become popular for detailed biophysical and structural studies of these complex proteins. This work has included recent applications to cellular liquid-liquid phase separation (LLPS), relevant for functional dynamics of membraneless organelles such as the nucleolus and stress granules. In this concise review, we cover the conceptual motivations for development and application of single-molecule fluorescence methods for such IDP studies. We follow with a few key examples of systems and biophysical problems that have been addressed, and conclude with thoughts for emerging and future directions.
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87
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Extreme mechanical diversity of human telomeric DNA revealed by fluorescence-force spectroscopy. Proc Natl Acad Sci U S A 2019; 116:8350-8359. [PMID: 30944218 DOI: 10.1073/pnas.1815162116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G-quadruplexes (GQs) can adopt diverse structures and are functionally implicated in transcription, replication, translation, and maintenance of telomere. Their conformational diversity under physiological levels of mechanical stress, however, is poorly understood. We used single-molecule fluorescence-force spectroscopy that combines fluorescence resonance energy transfer with optical tweezers to measure human telomeric sequences under tension. Abrupt GQ unfolding with K+ in solution occurred at as many as four discrete levels of force. Added to an ultrastable state and a gradually unfolding state, there were six mechanically distinct structures. Extreme mechanical diversity was also observed with Na+, although GQs were mechanically weaker. Our ability to detect small conformational changes at low forces enabled the determination of refolding forces of about 2 pN. Refolding was rapid and stochastically redistributed molecules to mechanically distinct states. A single guanine-to-thymine substitution mutant required much higher ion concentrations to display GQ-like unfolding and refolded via intermediates, contrary to the wild type. Contradicting an earlier proposal, truncation to three hexanucleotide repeats resulted in a single-stranded DNA-like mechanical behavior under all conditions, indicating that at least four repeats are required to form mechanically stable structures.
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88
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Isaacoff BP, Li Y, Lee SA, Biteen JS. SMALL-LABS: Measuring Single-Molecule Intensity and Position in Obscuring Backgrounds. Biophys J 2019; 116:975-982. [PMID: 30846363 DOI: 10.1016/j.bpj.2019.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 01/27/2019] [Accepted: 02/07/2019] [Indexed: 11/19/2022] Open
Abstract
Single-molecule and super-resolution imaging relies on successful, sensitive, and accurate detection of the emission from fluorescent molecules. Yet, despite the widespread adoption of super-resolution microscopies, single-molecule data processing algorithms can fail to provide accurate measurements of the brightness and position of molecules in the presence of backgrounds that fluctuate significantly over time and space. Thus, samples or experiments that include obscuring backgrounds can severely, or even completely, hinder this process. To date, no general data analysis approach to this problem has been introduced that is capable of removing obscuring backgrounds for a wide variety of experimental modalities. To address this need, we present the Single-Molecule Accurate LocaLization by LocAl Background Subtraction (SMALL-LABS) algorithm, which can be incorporated into existing single-molecule and super-resolution analysis packages to accurately locate and measure the intensity of single molecules, regardless of the shape or brightness of the background. Accurate background subtraction is enabled by separating the foreground from the background based on differences in the temporal variations of the foreground and the background (i.e., fluorophore blinking, bleaching, or moving). We detail the function of SMALL-LABS here, and we validate the SMALL-LABS algorithm on simulated data as well as real data from single-molecule imaging in living cells.
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Affiliation(s)
| | - Yilai Li
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Stephen A Lee
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Julie S Biteen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan.
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89
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Katranidis A, Fitter J. Single-Molecule Techniques and Cell-Free Protein Synthesis: A Perfect Marriage. Anal Chem 2019; 91:2570-2576. [PMID: 30648382 DOI: 10.1021/acs.analchem.8b03855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-molecule techniques are currently an essential tool to study conformational changes as well as the synthesis and folding of proteins. However, the preparation of suitable protein samples is often time-consuming and demanding. The rapid development of cell-free protein synthesis over the last few years opened new perspectives for fast and easy sample preparation, but this was not fully exploited until now. Here, we take a look at the advancements in sample preparation as well as in the development of technical approaches and analytical tools, which unavoidably lead to the combination of single-molecule techniques and cell-free protein synthesis. It is an ideal combination that can unlock the full potential of studying complex biological processes in the near future.
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Affiliation(s)
| | - Jörg Fitter
- Forschungszentrum Jülich , Institute of Complex Systems ICS-5, Jülich , Germany.,RWTH Aachen , I. Physikalisches Institut (IA) , Aachen , Germany
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90
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Ye R, Mao X, Sun X, Chen P. Analogy between Enzyme and Nanoparticle Catalysis: A Single-Molecule Perspective. ACS Catal 2019. [DOI: 10.1021/acscatal.8b04926] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Rong Ye
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Xianwen Mao
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Xiangcheng Sun
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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91
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Onoshima D, Yukawa H, Baba Y. Nanobiodevices for Cancer Diagnostics and Stem Cell Therapeutics. Bioanalysis 2019. [DOI: 10.1007/978-981-13-6229-3_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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92
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Abstract
This chapter expounds the single vesicle-vesicle fluorescence resonance energy transfer (FRET) measurement to study the membrane fusion mediated by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. The formation of a four-α-helix bundle of SNARE proteins can drive two membranes to a close proximity for fusion. Through single-molecule FRET-based microscopy, the lipid-mixing process at the single-vesicle level can be tracked in real time. This reconstitution system is applicable to study the molecular mechanism of SNAREs during different membrane fusion stages, such as docking, hemifusion, and full fusion. Four main parts are described in this chapter, including SNARE reconstitution, imaging preparation, data collection, and analysis.
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Affiliation(s)
- Yachong Hu
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Zhiqi Tian
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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93
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Gong W, Das P, Samanta S, Xiong J, Pan W, Gu Z, Zhang J, Qu J, Yang Z. Redefining the photo-stability of common fluorophores with triplet state quenchers: mechanistic insights and recent updates. Chem Commun (Camb) 2019; 55:8695-8704. [PMID: 31073568 DOI: 10.1039/c9cc02616a] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Light microscopy can offer certain advantages over electron microscopy in terms of acquiring detailed insights into the biological/intra-cellular milieu. In recent years, with the development of new fluorescence imaging technologies, it has become extremely important to assess the role of designing appropriate fluorophores in acquiring desired biological information without encountering any untoward hitches. Over the years, external fluorophores have been prevalently used in fluorescence microscopy and single-molecule fluorescence microscopy-based studies. Photostable fluorogenic probes with high extinction coefficients and quantum yields, exhibiting minimum autofluorescence and photobleaching properties, are preferred in single-molecule microscopy as they can tolerate long-term laser exposure. Therefore, the development of triplet state quenchers and/or any other suitable new strategy to ensure the photo-stability of the fluorophores during long-term live cell imaging exercises is highly anticipated. In this feature article, various strategies for stabilizing fluorophores, including the mechanisms of TSQ-induced stabilization, have been thoroughly reviewed considering contemporary literature reports and applications.
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Affiliation(s)
- Wanjun Gong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
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94
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Fontana M, Fijen C, Lemay SG, Mathwig K, Hohlbein J. High-throughput, non-equilibrium studies of single biomolecules using glass-made nanofluidic devices. LAB ON A CHIP 2018; 19:79-86. [PMID: 30468446 DOI: 10.1039/c8lc01175c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Single-molecule detection schemes offer powerful means to overcome static and dynamic heterogeneity inherent to complex samples. However, probing biomolecular interactions and reactions with high throughput and time resolution remains challenging, often requiring surface-immobilized entities. Here, we introduce glass-made nanofluidic devices for the high-throughput detection of freely-diffusing single biomolecules by camera-based fluorescence microscopy. Nanochannels of 200 nm height and a width of several micrometers confine the movement of biomolecules. Using pressure-driven flow through an array of parallel nanochannels and by tracking the movement of fluorescently labelled DNA oligonucleotides, we observe conformational changes with high throughput. In a device geometry featuring a T-shaped junction of nanochannels, we drive steady-state non-equilibrium conditions by continuously mixing reactants and triggering chemical reactions. We use the device to probe the conformational equilibrium of a DNA hairpin as well as to continuously observe DNA synthesis in real time. Our platform offers a straightforward and robust method for studying reaction kinetics at the single-molecule level.
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Affiliation(s)
- Mattia Fontana
- Laboratory of Biophysics, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
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95
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Wickersham CE, Lipman EA. Tracking DNA Synthesis with Single-Molecule Strand Displacement. J Phys Chem B 2018; 122:11546-11553. [PMID: 30284831 DOI: 10.1021/acs.jpcb.8b07440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that double-stranded DNA labeled with a periodic series of fluorescent dyes can be used to track a single helicase. Here we demonstrate how this technique can be adapted to follow processive DNA synthesis. By monitoring strand displacement, we track the motion of a single ϕ29 DNA polymerase without labeling or altering the enzyme or the template strand, and without applying any force. We observe a wide range of speeds, with the highest exceeding by several times those observed in earlier in vitro single-molecule experiments. Because this method enables repeated observations of the same polymerase traversing identical segments of DNA, it should prove useful for determining the effects of sequence on DNA replication and transcription. In addition, future measurements of this type may allow us to examine in detail the interactions of individual DNA polymerases with other components of the replisome.
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96
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Meena GG, Jain A, Parks JW, Stambaugh A, Patterson JL, Hawkins AR, Schmidt H. Integration of sample preparation and analysis into an optofluidic chip for multi-target disease detection. LAB ON A CHIP 2018; 18:3678-3686. [PMID: 30376021 PMCID: PMC6264894 DOI: 10.1039/c8lc00966j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Detection of molecular biomarkers with high specificity and sensitivity from biological samples requires both sophisticated sample preparation and subsequent analysis. These tasks are often carried out on separate platforms which increases required sample volumes and the risk of errors, sample loss, and contamination. Here, we present an optofluidic platform which combines an optical detection section with single nucleic acid strand sensitivity, and a sample processing unit capable of on-chip, specific extraction and labeling of nucleic acid and protein targets in complex biological matrices. First, on-chip labeling and detection of individual lambda DNA molecules down to concentrations of 8 fM is demonstrated. Subsequently, we demonstrate the simultaneous capture, fluorescence tagging and detection of both Zika specific nucleic acid and NS-1 protein targets in both buffer and human serum. We show that the dual DNA and protein assay allows for successful differentiation and diagnosis of Zika against cross-reacting species like dengue.
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Affiliation(s)
- Gopikrishnan G Meena
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Aadhar Jain
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Joshua W Parks
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Alexandra Stambaugh
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Jean L Patterson
- Department of Virology and Immunology, Texas Biomedical Research Institute, 7620 NW Loop 410, San Antonio, TX 78227, USA
| | - Aaron R Hawkins
- ECEn Department, Brigham Young University, 459 Clyde Building, Provo, UT 84602, USA
| | - Holger Schmidt
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
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97
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Duss O, Stepanyuk GA, Grot A, O'Leary SE, Puglisi JD, Williamson JR. Real-time assembly of ribonucleoprotein complexes on nascent RNA transcripts. Nat Commun 2018; 9:5087. [PMID: 30504830 PMCID: PMC6269517 DOI: 10.1038/s41467-018-07423-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/26/2018] [Indexed: 12/22/2022] Open
Abstract
Cellular protein-RNA complexes assemble on nascent transcripts, but methods to observe transcription and protein binding in real time and at physiological concentrations are not available. Here, we report a single-molecule approach based on zero-mode waveguides that simultaneously tracks transcription progress and the binding of ribosomal protein S15 to nascent RNA transcripts during early ribosome biogenesis. We observe stable binding of S15 to single RNAs immediately after transcription for the majority of the transcripts at 35 °C but for less than half at 20 °C. The remaining transcripts exhibit either rapid and transient binding or are unable to bind S15, likely due to RNA misfolding. Our work establishes the foundation for studying transcription and its coupled co-transcriptional processes, including RNA folding, ligand binding, and enzymatic activity such as in coupling of transcription to splicing, ribosome assembly or translation. The early steps of ribosome assembly occur co-transcriptionally on the nascent ribosomal RNA. Here the authors demonstrate an approach that allows simultaneous monitoring of transcription and ribosomal protein assembly at the single-molecule level in real time.
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Affiliation(s)
- Olivier Duss
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA.,Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA
| | - Galina A Stepanyuk
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Annette Grot
- Department of Research and Development, Pacific Biosciences Inc, Menlo Park, CA, 94025, USA
| | - Seán E O'Leary
- Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA.,Department of Biochemistry, University of California, Riverside, CA, 92521, USA
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA.
| | - James R Williamson
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
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98
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Gidi Y, Bayram S, Ablenas CJ, Blum AS, Cosa G. Efficient One-Step PEG-Silane Passivation of Glass Surfaces for Single-Molecule Fluorescence Studies. ACS APPLIED MATERIALS & INTERFACES 2018; 10:39505-39511. [PMID: 30346695 DOI: 10.1021/acsami.8b15796] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Surface passivation to inhibit nonspecific interactions is a key requirement for in vitro single-molecule fluorescent studies. Although the standard passivation methods involve the covalent attachment of poly(ethylene glycol) (PEG) in two steps preferably over quartz surfaces, this protocol and improvements thereon require extensive labor and chemicals. Herein, we report an efficient one-step surface grafting of PEG-silane that yields enhanced passivation, as evidenced by reduced nonspecific interactions, over the conventional method at a minimal time and reagent cost and on glass surfaces. Our method is rooted in a mechanistic understanding of the silane reaction with the silanol groups on the glass surface. Single-molecule fluorescence studies with fluorescently tagged proteins and DNA on PEG-silane-functionalized glass surfaces validate the enhanced performance of the method. Combined with atomic force microscopy surface characterization, our study further illustrates that few remaining pinhole defects, plausibly from defects on the glass, on PEG-silane glass-coated surfaces account for the minimal background, where typically no more than one molecule is nonspecifically attached in a given diffraction-limited spot on the surface.
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Affiliation(s)
- Yasser Gidi
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM) , McGill University , 801 Sherbrooke Street West , Montreal , Quebec H3A 0B8 , Canada
| | - Serene Bayram
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM) , McGill University , 801 Sherbrooke Street West , Montreal , Quebec H3A 0B8 , Canada
| | | | - Amy Szuchmacher Blum
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM) , McGill University , 801 Sherbrooke Street West , Montreal , Quebec H3A 0B8 , Canada
| | - Gonzalo Cosa
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM) , McGill University , 801 Sherbrooke Street West , Montreal , Quebec H3A 0B8 , Canada
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99
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Cui Y, Yu M, Yao X, Xing J, Lin J, Li X. Single-Particle Tracking for the Quantification of Membrane Protein Dynamics in Living Plant Cells. MOLECULAR PLANT 2018; 11:1315-1327. [PMID: 30296600 DOI: 10.1016/j.molp.2018.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/26/2018] [Accepted: 09/26/2018] [Indexed: 05/25/2023]
Abstract
The plasma membrane is a sophisticated, organized, and highly heterogeneous structure that compartmentalizes cellular processes. To decipher the biological processes involving membrane proteins, it is necessary to analyze their spatiotemporal dynamics. However, it is difficult to directly assess the dynamics and interactions of biomolecules in living cells using traditional biochemical methods. Single-particle tracking (SPT) methods for imaging and tracking single particles conjugated with fluorescent probes offer an ideal approach to acquire valuable and complementary information about dynamic intracellular processes. SPT can be used to quantitatively monitor the diverse motions of individual particles in living cells. SPT also provides super-spatiotemporal resolution that allows early-stage or rapid response information to be obtained for a better understanding of molecular basis of associated signal transduction processes. More importantly, SPT can be used to detect the motion paths of individual biomolecules in vivo and in situ, thus unveiling the dynamic behavior of the biomolecules that support developmental processes in living cells. In this review, we give an overview of SPT methods, from image acquisition to the detection of single particles, as well as tracking and data analysis. We also discuss recent applications of SPT methods in the field of plant biology to reveal the complex biological functions of membrane proteins.
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Affiliation(s)
- Yaning Cui
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China; College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Meng Yu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China; College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Xiaomin Yao
- College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Jingjing Xing
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology, Henan University, Jinming Street, Kaifeng 475001, China
| | - Jinxing Lin
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China; College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Xiaojuan Li
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China; College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing 100083, China.
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Ray S, Chauvier A, Walter NG. Kinetics coming into focus: single-molecule microscopy of riboswitch dynamics. RNA Biol 2018; 16:1077-1085. [PMID: 30328748 DOI: 10.1080/15476286.2018.1536594] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Riboswitches are dynamic RNA motifs that are mostly embedded in the 5'-untranslated regions of bacterial mRNAs, where they regulate gene expression transcriptionally or translationally by undergoing conformational changes upon binding of a small metabolite or ion. Due to the small size of typical ligands, relatively little free energy is available from ligand binding to overcome the often high energetic barrier of reshaping RNA structure. Instead, most riboswitches appear to take advantage of the directional and hierarchical folding of RNA by employing the ligand as a structural 'linchpin' to adjust the kinetic partitioning between alternate folds. In this model, even small, local structural and kinetic effects of ligand binding can cascade into global RNA conformational changes affecting gene expression. Single-molecule (SM) microscopy tools are uniquely suited to study such kinetically controlled RNA folding since they avoid the ensemble averaging of bulk techniques that loses sight of unsynchronized, transient, and/or multi-state kinetic behavior. This review summarizes how SM methods have begun to unravel riboswitch-mediated gene regulation.
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Affiliation(s)
- Sujay Ray
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
| | - Adrien Chauvier
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
| | - Nils G Walter
- a Single Molecule Analysis Group, Department of Chemistry, University of Michigan , Ann Arbor , MI , USA
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