1
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Velasco L, Islam AN, Kundu K, Oi A, Reinhard BM. Two-color interferometric scattering (iSCAT) microscopy reveals structural dynamics in discrete plasmonic molecules. NANOSCALE 2024; 16:11696-11704. [PMID: 38860984 PMCID: PMC11189637 DOI: 10.1039/d4nr01288g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 06/03/2024] [Indexed: 06/12/2024]
Abstract
Plasmonic molecules are discrete assemblies of noble metal nanoparticles (NPs) that are of interest as transducers in optical nanosensors. So far, NPs with diameters of ∼40 nm have been the preferred building blocks for plasmonic molecules intended as optical single molecule sensors due to difficulties associated with detecting smaller NPs through elastic scattering in conventional darkfield microscopy. Here, we apply 405 nm, 445 nm two-color interferometric scattering (iSCAT) microscopy to characterize polyethylene glycol (PEG) tethered dimers of 10 nm and 20 nm Ag NPs and their monomers. Dimers of both NP sizes can be discerned from their respective monomers through changes in the average iSCAT contrast. In the case of 20 nm Ag NPs, dimer formation induces a change in the sign of the iSCAT contrast, providing a characteristic signal for detecting binding events. 20 nm Ag NP dimers with 0.4 kDa and 3.4 kDa polyethylene glycol (PEG) spacers show iSCAT contrast distributions with significantly different averages on both wavelength channels. The iSCAT contrast measured for individual PEG-tethered 10 nm or 20 nm NP dimers as a function of time shows contrast fluctuations indicative of a rich structural dynamics in the assembled plasmonic molecules, which provides an additional metric to discern dimers from monomers and paves the path to a new class of interferometric plasmon rulers.
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Affiliation(s)
- Leslie Velasco
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
| | - Aniqa N Islam
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
| | - Koustav Kundu
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
| | - Aidan Oi
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
| | - Björn M Reinhard
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
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2
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Spudich JA. One must reconstitute the functions of interest from purified proteins. Front Physiol 2024; 15:1390186. [PMID: 38827995 PMCID: PMC11140241 DOI: 10.3389/fphys.2024.1390186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 04/01/2024] [Indexed: 06/05/2024] Open
Abstract
I am often asked by students and younger colleagues and now by the editors of this issue to tell the history of the development of the in vitro motility assay and the dual-beam single-molecule laser trap assay for myosin-driven actin filament movement, used widely as key assays for understanding how both muscle and nonmuscle myosin molecular motors work. As for all discoveries, the history of the development of the myosin assays involves many people who are not authors of the final publications, but without whom the assays would not have been developed as they are. Also, early experiences shape how one develops ideas and experiments, and influence future discoveries in major ways. I am pleased here to trace my own path and acknowledge the many individuals involved and my early science experiences that led to the work I and my students, postdoctoral fellows, and sabbatical visitors did to develop these assays. Mentors are too often overlooked in historical descriptions of discoveries, and my story starts with those who mentored me.
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Affiliation(s)
- James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States
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3
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Yan X, Yu PY, Srinivasan A, Abdul Rehman S, Prigozhin MB. Identifying Intermolecular Interactions in Single-Molecule Localization Microscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593617. [PMID: 38798627 PMCID: PMC11118527 DOI: 10.1101/2024.05.10.593617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Intermolecular interactions underlie all cellular functions, yet visualizing these interactions at the single-molecule level remains challenging. Single-molecule localization microscopy (SMLM) offers a potential solution. Given a nanoscale map of two putative interaction partners, it should be possible to assign molecules either to the class of coupled pairs or to the class of non-coupled bystanders. Here, we developed a probabilistic algorithm that allows accurate determination of both the absolute number and the proportion of molecules that form coupled pairs. The algorithm calculates interaction probabilities for all possible pairs of localized molecules, selects the most likely interaction set, and corrects for any spurious colocalizations. Benchmarking this approach across a set of simulated molecular localization maps with varying densities (up to ∼ 50 molecules µm - 2 ) and localization precisions (5 to 50 nm) showed typical errors in the identification of correct pairs of only a few percent. At molecular densities of ∼ 5-10 molecules µm - 2 and localization precisions of 20-30 nm, which are typical parameters for SMLM imaging, the recall was ∼ 90%. The algorithm was effective at differentiating between non-interacting and coupled molecules both in simulations and experiments. Finally, it correctly inferred the number of coupled pairs over time in a simulated reaction-diffusion system, enabling determination of the underlying rate constants. The proposed approach promises to enable direct visualization and quantification of intermolecular interactions using SMLM.
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4
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Hernandez AC, Ortiz S, Betancur LI, Dojčilović R, Picco A, Kaksonen M, Oliva B, Gallego O. PyF2F: a robust and simplified fluorophore-to-fluorophore distance measurement tool for Protein interactions from Imaging Complexes after Translocation experiments. NAR Genom Bioinform 2024; 6:lqae027. [PMID: 38486885 PMCID: PMC10939353 DOI: 10.1093/nargab/lqae027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/31/2024] [Accepted: 02/27/2024] [Indexed: 03/17/2024] Open
Abstract
Structural knowledge of protein assemblies in their physiological environment is paramount to understand cellular functions at the molecular level. Protein interactions from Imaging Complexes after Translocation (PICT) is a live-cell imaging technique for the structural characterization of macromolecular assemblies in living cells. PICT relies on the measurement of the separation between labelled molecules using fluorescence microscopy and cell engineering. Unfortunately, the required computational tools to extract molecular distances involve a variety of sophisticated software programs that challenge reproducibility and limit their implementation to highly specialized researchers. Here we introduce PyF2F, a Python-based software that provides a workflow for measuring molecular distances from PICT data, with minimal user programming expertise. We used a published dataset to validate PyF2F's performance.
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Affiliation(s)
- Altair C Hernandez
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
| | - Sebastian Ortiz
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
| | - Laura I Betancur
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
| | - Radovan Dojčilović
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
| | - Andrea Picco
- Department of Biochemistry, University of Geneva, 1205 Genève, Switzerland
| | - Marko Kaksonen
- Department of Biochemistry, University of Geneva, 1205 Genève, Switzerland
| | - Baldo Oliva
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
| | - Oriol Gallego
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona 08005, Catalonia, Spain
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5
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van den Wildenberg SMJL, Prevo B, Peterman EJG. A Brief Introduction to Single-Molecule Fluorescence Methods. Methods Mol Biol 2024; 2694:111-132. [PMID: 37824002 DOI: 10.1007/978-1-0716-3377-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
One of the most popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which will be the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also allow access to useful measurable parameters on time and length scales relevant for the biomolecular world. Before several detailed experimental approaches will be addressed, we will first give a general overview of single-molecule fluorescence microscopy. We start with discussing the phenomenon of fluorescence in general and the history of single-molecule fluorescence microscopy. Next, we will review fluorescent probes in more detail and the equipment required to visualize them on the single-molecule level. We will end with a description of parameters measurable with such approaches, ranging from protein counting and tracking, single-molecule localization super-resolution microscopy, to distance measurements with Förster resonance energy transfer and orientation measurements with fluorescence polarization.
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Affiliation(s)
- Siet M J L van den Wildenberg
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, France
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, Clermont-Ferrand, France
| | - Bram Prevo
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Erwin J G Peterman
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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6
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Shelby SA, Castello-Serrano I, Wisser KC, Levental I, Veatch SL. Membrane phase separation drives responsive assembly of receptor signaling domains. Nat Chem Biol 2023; 19:750-758. [PMID: 36997644 PMCID: PMC10771812 DOI: 10.1038/s41589-023-01268-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 01/17/2023] [Indexed: 04/01/2023]
Abstract
Plasma membrane heterogeneity has been tied to a litany of cellular functions and is often explained by analogy to membrane phase separation; however, models based on phase separation alone fall short of describing the rich organization available within cell membranes. Here we present comprehensive experimental evidence motivating an updated model of plasma membrane heterogeneity in which membrane domains assemble in response to protein scaffolds. Quantitative super-resolution nanoscopy measurements in live B lymphocytes detect membrane domains that emerge upon clustering B cell receptors (BCRs). These domains enrich and retain membrane proteins based on their preference for the liquid-ordered phase. Unlike phase-separated membranes that consist of binary phases with defined compositions, membrane composition at BCR clusters is modulated through the protein constituents in clusters and the composition of the membrane overall. This tunable domain structure is detected through the variable sorting of membrane probes and impacts the magnitude of BCR activation.
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Affiliation(s)
- Sarah A Shelby
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Ivan Castello-Serrano
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | | | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA.
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7
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Loi J, Qu X, Suzuki A. Semi-automated 3D fluorescence speckle analyzer (3D-Speckler) for microscope calibration and nanoscale measurement. J Cell Biol 2023; 222:213839. [PMID: 36715673 PMCID: PMC9929931 DOI: 10.1083/jcb.202202078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 08/25/2022] [Accepted: 01/05/2023] [Indexed: 01/31/2023] Open
Abstract
The widespread use of fluorescence microscopy has prompted the ongoing development of tools aiming to improve resolution and quantification accuracy for study of biological questions. Current calibration and quantification tools for fluorescence images face issues with usability/user experience, lack of automation, and comprehensive multidimensional measurement/correction capabilities. Here, we developed 3D-Speckler, a versatile, and high-throughput image analysis software that can provide fluorescent puncta quantification measurements such as 2D/3D particle size, spatial location/orientation, and intensities through semi-automation in a single, user-friendly interface. Integrated analysis options such as 2D/3D local background correction, chromatic aberration correction, and particle matching/filtering are also encompassed for improved precision and accuracy. We demonstrate 3D-Speckler microscope calibration capabilities by determining the chromatic aberrations, field illumination uniformity, and response to nanometer-scale emitters above and below the diffraction limit of our imaging system using multispectral beads. Furthermore, we demonstrated 3D-Speckler quantitative capabilities for offering insight into protein architectures and composition in cells.
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Affiliation(s)
- Jonathan Loi
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA,Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Xiaofei Qu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, Madison, WI, USA,Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI, USA,Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison, WI, USA,Correspondence to Aussie Suzuki:
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8
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Schirripa Spagnolo C, Luin S. Setting up multicolour TIRF microscopy down to the single molecule level. Biomol Concepts 2023; 14:bmc-2022-0032. [PMID: 37428621 DOI: 10.1515/bmc-2022-0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023] Open
Abstract
Investigating biological mechanisms in ever greater detail requires continuous advances in microscopy techniques and setups. Total internal reflection fluorescence (TIRF) microscopy is a well-established technique for visualizing processes on the cell membrane. TIRF allows studies down to the single molecule level, mainly in single-colour applications. Instead, multicolour setups are still limited. Here, we describe our strategies for implementing a multi-channel TIRF microscopy system capable of simultaneous two-channel excitation and detection, starting from a single-colour commercial setup. First, we report some applications at high molecule density and then focus on the challenges we faced for achieving the single molecule level simultaneously in different channels, showing that rigorous optimizations on the setup are needed to increase its sensitivity up to this point, from camera setting to background minimization. We also discuss our strategies regarding crucial points of fluorescent labelling for this type of experiment: labelling strategy, kind of probe, efficiency, and orthogonality of the reaction, all of which are aspects that can influence the achievable results. This work may provide useful guidelines for setting up advanced single-molecule multi-channel TIRF experiments to obtain insights into interaction mechanisms on the cell membrane of living cells.
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Affiliation(s)
| | - Stefano Luin
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, I-56127, Pisa, Italy
- NEST Laboratory, Istituto Nanoscienze-Consiglio Nazionale delle ricerche (CNR), Piazza San Silvestro 12, I-56127, Pisa, Italy
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9
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Shelby SA, Shaw TR, Veatch SL. Measuring the Co-Localization and Dynamics of Mobile Proteins in Live Cells Undergoing Signaling Responses. Methods Mol Biol 2023; 2654:1-23. [PMID: 37106172 PMCID: PMC10758997 DOI: 10.1007/978-1-0716-3135-5_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Single molecule imaging in live cells enables the study of protein interactions and dynamics as they participate in signaling processes. When combined with fluorophores that stochastically transition between fluorescent and reversible dark states, as in super-resolution localization imaging, labeled molecules can be visualized in single cells over time. This improvement in sampling enables the study of extended cellular responses at the resolution of single molecule localization. This chapter provides optimized experimental and analytical methods used to quantify protein interactions and dynamics within the membranes of adhered live cells. Importantly, the use of pair-correlation functions resolved in both space and time allows researchers to probe interactions between proteins on biologically relevant distance and timescales, even though fluorescence localization methods typically require long times to assemble well-sampled reconstructed images. We describe an application of this approach to measure protein interactions in B cell receptor signaling and include sample analysis code for post-processing of imaging data. These methods are quantitative, sensitive, and broadly applicable to a range of signaling systems.
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Affiliation(s)
- Sarah A Shelby
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Thomas R Shaw
- Program in Applied Physics, University of Michigan, Ann Arbor, MI, USA
| | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA.
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10
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Embacher PA, Germanova TE, Roscioli E, McAinsh AD, Burroughs NJ. Bayesian inference of multi-point macromolecular architecture mixtures at nanometre resolution. PLoS Comput Biol 2022; 18:e1010765. [PMID: 36574448 PMCID: PMC9829179 DOI: 10.1371/journal.pcbi.1010765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/09/2023] [Accepted: 11/28/2022] [Indexed: 12/29/2022] Open
Abstract
Gaussian spot fitting methods have significantly extended the spatial range where fluorescent microscopy can be used, with recent techniques approaching nanometre (nm) resolutions. However, small inter-fluorophore distances are systematically over-estimated for typical molecular scales. This bias can be corrected computationally, but current algorithms are limited to correcting distances between pairs of fluorophores. Here we present a flexible Bayesian computational approach that infers the distances and angles between multiple fluorophores and has several advantages over these previous methods. Specifically it improves confidence intervals for small lengths, estimates measurement errors of each fluorophore individually and infers the correlations between polygon lengths. The latter is essential for determining the full multi-fluorophore 3D architecture. We further developed the algorithm to infer the mixture composition of a heterogeneous population of multiple polygon states. We use our algorithm to analyse the 3D architecture of the human kinetochore, a macro-molecular complex that is essential for high fidelity chromosome segregation during cell division. Using triple fluorophore image data we unravel the mixture of kinetochore states during human mitosis, inferring the conformation of microtubule attached and unattached kinetochores and their proportions across mitosis. We demonstrate that the attachment conformation correlates with intersister tension and sister alignment to the metaphase plate.
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Affiliation(s)
- Peter A. Embacher
- Department of Medical Physics & Biomedical Engineering, University College London, London, United Kingdom
| | - Tsvetelina E. Germanova
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Emanuele Roscioli
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Andrew D. McAinsh
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Nigel J. Burroughs
- Mathematics Institute and Zeeman Institute, University of Warwick, Coventry, United Kingdom
- * E-mail:
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11
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Extraction of accurate cytoskeletal actin velocity distributions from noisy measurements. Nat Commun 2022; 13:4749. [PMID: 35963858 PMCID: PMC9376101 DOI: 10.1038/s41467-022-31583-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 06/23/2022] [Indexed: 11/09/2022] Open
Abstract
Dynamic remodeling of the actin cytoskeleton is essential for many cellular processes. Tracking the movement of individual actin filaments can in principle shed light on how this complex behavior arises at the molecular level. However, the information that can be extracted from these measurements is often limited by low signal-to-noise ratios. We developed a Bayesian statistical approach to estimate true, underlying velocity distributions from the tracks of individual actin-associated fluorophores with quantified localization uncertainties. We found that the motion of filamentous (F)-actin in fibroblasts and endothelial cells was better described by a statistical jump process than by models in which filaments undergo continuous, diffusive movement. In particular, a model with exponentially distributed jump length- and time-scales recapitulated actin filament velocity distributions measured for the cell cortex, integrin-based adhesions, and stress fibers, suggesting that a common physical model can potentially describe actin filament dynamics in a variety of cellular contexts.
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12
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Germanova TE, Roscioli E, Harrison JU, McAinsh AD, Burroughs NJ. Subcellular Euclidean distance measurements with multicolor fluorescence localization imaging in cultured cells. STAR Protoc 2021; 2:100774. [PMID: 34841272 PMCID: PMC8605398 DOI: 10.1016/j.xpro.2021.100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This protocol measures the 3D Euclidean distance (Δ3D) between two/three fluorescently labeled kinetochore components in fixed samples using Kinetochore Delta software (KiDv1.0.1, MATLAB based). Overestimation of mean Δ3D is corrected through a Bayesian algorithm, with ΔEC distances reflecting the ensemble average positions of fluorophores within a kinetochore population. This package also enables kinetochore categorization, which can be used to sub-sample kinetochores and measure ΔEC. Together, this allows the dynamic architecture of human kinetochores to be investigated (tested in hTERT-RPE1 cells). For complete details on the use and execution of this protocol, please refer to Roscioli et al. (2020). Measurements of intra-kinetochore distances from multi-color image stacks Automated detection of fluorescent spot centers with sub-pixel accuracy GUI-based pipeline to enable spot classification and data quality control Bayesian algorithm to correct for over-estimation of Euclidian distances
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Affiliation(s)
- Tsvetelina E Germanova
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry CV47AL, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Emanuele Roscioli
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry CV47AL, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | | | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry CV47AL, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Nigel J Burroughs
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry CV47AL, UK.,Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK
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13
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Yang Y, Tan Y, Zhangsun D, Zhu X, Luo S. Design, Synthesis, and Activity of an α-Conotoxin LtIA Fluorescent Analogue. ACS Chem Neurosci 2021; 12:3662-3671. [PMID: 34523332 DOI: 10.1021/acschemneuro.1c00392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are essential pentameric ligand-gated ion channels that are distributed throughout the central and peripheral nervous systems and non-neuronal tissues in mammalian species that play critical roles in a variety of neural and mental activities. The α3β2 nAChR subtype participates in pain, addiction to nicotine, and other neurophysiological and pathological activities. Owing to the lack of highly selective pharmacological tools targeting α3β2, related research on its tissue distribution and function has been hindered. α-Conotoxin (α-CTx) LtIA, discovered from Conus literatus in our lab, potently and selectively blocks α3β2 nAChR, providing an important molecular probe to study the α3β2 nAChR structure and function. We used the fluorescent molecule 5-carboxytetramethylrhodamine succinimidyl ester, which can react with the N-terminus of LtIA, to obtain a novel fluorescent analogue of LtIA (LtIA-F). The potency and selectivity of LtIA-F were tested using a two-electrode voltage clamp recording on various nAChRs expressed in Xenopus laevis oocytes. LtIA-F potently inhibited ACh-evoked currents at the α3β2 nAChR, with an IC50 value of 90.66 nM, displaying a ∼4-fold decrease in potency compared with native LtIA without a change in selectivity. The serum stability results indicated that LtIA-F exhibited stability similar to that of native LtIA. This study on an α-CTx LtIA fluorescent analogue provides a wealth of pharmacological tools to explore the structure-function relationship, distribution, and ligand binding domain of the α3β2 nAChR subtype.
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Affiliation(s)
- Yishuai Yang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Yao Tan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Medical School, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China
- Medical School, Guangxi University, Nanning 530004, China
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14
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Auer JMT, Stoddart JJ, Christodoulou I, Lima A, Skouloudaki K, Hall HN, Vukojević V, Papadopoulos DK. Of numbers and movement - understanding transcription factor pathogenesis by advanced microscopy. Dis Model Mech 2020; 13:dmm046516. [PMID: 33433399 PMCID: PMC7790199 DOI: 10.1242/dmm.046516] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Transcription factors (TFs) are life-sustaining and, therefore, the subject of intensive research. By regulating gene expression, TFs control a plethora of developmental and physiological processes, and their abnormal function commonly leads to various developmental defects and diseases in humans. Normal TF function often depends on gene dosage, which can be altered by copy-number variation or loss-of-function mutations. This explains why TF haploinsufficiency (HI) can lead to disease. Since aberrant TF numbers frequently result in pathogenic abnormalities of gene expression, quantitative analyses of TFs are a priority in the field. In vitro single-molecule methodologies have significantly aided the identification of links between TF gene dosage and transcriptional outcomes. Additionally, advances in quantitative microscopy have contributed mechanistic insights into normal and aberrant TF function. However, to understand TF biology, TF-chromatin interactions must be characterised in vivo, in a tissue-specific manner and in the context of both normal and altered TF numbers. Here, we summarise the advanced microscopy methodologies most frequently used to link TF abundance to function and dissect the molecular mechanisms underlying TF HIs. Increased application of advanced single-molecule and super-resolution microscopy modalities will improve our understanding of how TF HIs drive disease.
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Affiliation(s)
- Julia M T Auer
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh EH4 1XU, UK
| | - Jack J Stoddart
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh EH4 1XU, UK
| | | | - Ana Lima
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh EH4 1XU, UK
| | | | - Hildegard N Hall
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh EH4 1XU, UK
| | - Vladana Vukojević
- Center for Molecular Medicine (CMM), Department of Clinical Neuroscience, Karolinska Institutet, 17176 Stockholm, Sweden
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15
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Zhang D, Liu SG, Fu Z, He Y, Gao W, Shi X. The method for integrating dual-color fluorescence colocalization and single molecule photobleaching technology on the theophylline sensing platform. MethodsX 2020; 7:101155. [PMID: 33304835 PMCID: PMC7708945 DOI: 10.1016/j.mex.2020.101155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/13/2020] [Indexed: 11/17/2022] Open
Abstract
• Smart usage of single molecule photobleaching technology and dual-color fluorescence colocalization is of critical importance for exploiting the sensing platform. Here, we provide the detailed protocols related to the article “A split aptamer sensing platform for highly sensitive detection of theophylline based on dual-color fluorescence colocalization and single molecule photobleaching” (published online by Biosensors and Bioelectronics) (Liu et al., 2020). The protocols contain: (1) how to clean the slides; (2) how to prepare the probe and detection sample; (3) Single molecule imaging; 4) Data processing by using the Image J. Finally, we used a simple model to confirm the feasibility of the method for integrating dual-color fluorescence colocalization and single molecule photobleaching technology on the theophylline sensing platform. • A simple, ultrasensitive method for the detection of theophylline. • The method is easily comprehensible. • Both strategy formulation and data processing are simple, learnability, and highly reproducible.
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Affiliation(s)
- Dong Zhang
- Laboratory of Micro and Nano Biosensing Technology in Food Safety, Hunan Provincial Key Laboratory of Food Science and Biotechnology, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Shi Gang Liu
- Laboratory of Micro and Nano Biosensing Technology in Food Safety, Hunan Provincial Key Laboratory of Food Science and Biotechnology, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Zhaodi Fu
- Analytical Testing Laboratory, Changsha Research Institute of Mining and Metallurgy CO., LTD., Changsha 410012, China
| | - Yu He
- Laboratory of Micro and Nano Biosensing Technology in Food Safety, Hunan Provincial Key Laboratory of Food Science and Biotechnology, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Wenli Gao
- Laboratory of Micro and Nano Biosensing Technology in Food Safety, Hunan Provincial Key Laboratory of Food Science and Biotechnology, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Xingbo Shi
- Laboratory of Micro and Nano Biosensing Technology in Food Safety, Hunan Provincial Key Laboratory of Food Science and Biotechnology, College of Food Science and Technology, Hunan Agricultural University, Changsha 410128, China
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17
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Dong B, Song KH, Davis JL, Zhang HF, Sun C. Sub-10-nm distance measurements between fluorophores using photon-accumulation enhanced reconstruction (PACER). ADVANCED PHOTONICS RESEARCH 2020; 1:2000038. [PMID: 33709086 PMCID: PMC7942786 DOI: 10.1002/adpr.202000038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Single-molecule localization microscopy (SMLM) precisely localizes individual fluorescent molecules within the wide field of view. However, the localization precision is fundamentally limited to around 20 nm due to the physical photon limit of individual stochastic single-molecule emissions. Using spectroscopic SMLM (sSMLM) to resolve their distinct fluorescence emission spectra, we can specifically distinguish and identify individual fluorophore, even the ones of the same type. Consequently, the reported photon-accumulation enhanced reconstruction (PACER) method accumulates photons over repeated stochastic emissions from the same fluorophore to significantly improve the localization precision. This work showed the feasibility of PACER by resolving quantum dots that were 6.1 nm apart with 1.7-nm localization precision. Next, a Monte Carlo simulation is used to investigate the success probability of PACER's classification process for distance measurements under different conditions. Finally, PACER is used to resolve and measure the lengths of DNA origami nanorulers with inter-molecular spacing as small as 6 nm. Notably, the demonstrated sub-2-nm localization precision bridges the detection range between Förster Resonance Energy Transfer (FRET) and conventional SMLM. Fully exploiting the underlying imaging capability can potentially enable high-throughput inter-molecular distance measurements over a large field of view.
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Affiliation(s)
- Biqin Dong
- Biomedical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
- Mechanical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
| | - Ki-Hee Song
- Biomedical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
| | - Janel L Davis
- Biomedical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
| | - Hao F Zhang
- Biomedical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
| | - Cheng Sun
- Mechanical Engineering Department, Northwestern University, Evanston, IL, 60208, USA
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18
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Li J, Zhang L, Johnson-Buck A, Walter NG. Automatic classification and segmentation of single-molecule fluorescence time traces with deep learning. Nat Commun 2020; 11:5833. [PMID: 33203879 PMCID: PMC7673028 DOI: 10.1038/s41467-020-19673-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 10/20/2020] [Indexed: 01/19/2023] Open
Abstract
Traces from single-molecule fluorescence microscopy (SMFM) experiments exhibit photophysical artifacts that typically necessitate human expert screening, which is time-consuming and introduces potential for user-dependent expectation bias. Here, we use deep learning to develop a rapid, automatic SMFM trace selector, termed AutoSiM, that improves the sensitivity and specificity of an assay for a DNA point mutation based on single-molecule recognition through equilibrium Poisson sampling (SiMREPS). The improved performance of AutoSiM is based on accepting both more true positives and fewer false positives than the conventional approach of hidden Markov modeling (HMM) followed by hard thresholding. As a second application, the selector is used for automated screening of single-molecule Förster resonance energy transfer (smFRET) data to identify high-quality traces for further analysis, and achieves ~90% concordance with manual selection while requiring less processing time. Finally, we show that AutoSiM can be adapted readily to novel datasets, requiring only modest Transfer Learning.
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Affiliation(s)
- Jieming Li
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA
- Bristol-Myers Squibb Company, New Brunswick, NJ, USA
| | - Leyou Zhang
- Department of Physics, The University of Michigan, Ann Arbor, MI, USA
- Google, Pittsburgh, PA, USA
| | - Alexander Johnson-Buck
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA.
- Department of Internal Medicine, Division of Hematology/Oncology, University of Michigan, Ann Arbor, MI, USA.
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA.
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Li Y, Yi J, Liu W, Liu Y, Liu J. Gaining insight into cellular cardiac physiology using single particle tracking. J Mol Cell Cardiol 2020; 148:63-77. [PMID: 32871158 DOI: 10.1016/j.yjmcc.2020.08.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 11/29/2022]
Abstract
Single particle tracking (SPT) is a robust technique to monitor single-molecule behaviors in living cells directly. By this approach, we can uncover the potential biological significance of particle dynamics by statistically characterizing individual molecular behaviors. SPT provides valuable information at the single-molecule level, that could be obscured by simple averaging that is inherent to conventional ensemble measurements. Here, we give a brief introduction to SPT including the commonly used optical implementations, fluorescence labeling strategies, and data analysis methods. We then focus on how SPT has been harnessed to decipher myocardial function. In this context, SPT has provided novel insight into the lateral diffusion of signal receptors and ion channels, the dynamic organization of cardiac nanodomains, subunit composition and stoichiometry of cardiac ion channels, myosin movement along actin filaments, the kinetic features of transcription factors involved in cardiac remodeling, and the intercellular communication by nanotubes. Finally, we speculate on the prospects and challenges of applying SPT to future questions regarding cellular cardiac physiology using SPT.
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Affiliation(s)
- Ying Li
- School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, 518060, China.
| | - Jing Yi
- School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, 518060, China.
| | - Wenjuan Liu
- School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, 518060, China.
| | - Yun Liu
- The Seventh Affiliated Hospital, Sun Yat-sen University, Guangdong Province, China.
| | - Jie Liu
- School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, 518060, China.
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20
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Renda F, Magidson V, Tikhonenko I, Fisher R, Miles C, Mogilner A, Khodjakov A. Effects of malleable kinetochore morphology on measurements of intrakinetochore tension. Open Biol 2020; 10:200101. [PMID: 32634373 PMCID: PMC7571466 DOI: 10.1098/rsob.200101] [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] [Indexed: 11/25/2022] Open
Abstract
The distance between fluorescent spots formed by various kinetochore proteins (delta) is commonly interpreted as a manifestation of intrakinetochore tension (IKT) caused by microtubule-mediated forces. However, large-scale changes of the kinetochore architecture (such as its shape or dimensions) may also contribute to the value of delta. To assess contributions of these non-elastic changes, we compare behaviour of delta values in human kinetochores with small yet mechanically malleable kinetochores against compound kinetochores in Indian muntjac (IM) cells whose architecture remains constant. Due to the micrometre-scale length of kinetochore plates in IM, their shape and orientation are discernible in conventional light microscopy, which enables precise measurements of IKT independent of contributions from changes in overall architecture of the organelle. We find that delta in IM kinetochores remains relatively constant when microtubule-mediated forces are suppressed by Taxol, but it prominently decreases upon detachment of microtubules. By contrast, large decreases of delta observed in Taxol-treated human cells coincide with prominent changes in length and curvature of the kinetochore plate. These observations, supported by computational modelling, suggest that at least 50% of the decrease in delta in human cells reflects malleable reorganization of kinetochore architecture rather than elastic recoil due to IKT.
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Affiliation(s)
- Fioranna Renda
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Valentin Magidson
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Irina Tikhonenko
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Rebecca Fisher
- New York State Department of Health, Wadsworth Center, Albany, NY, USA
| | - Christopher Miles
- Courant Institute and Department of Biology, New York University, New York, NY, USA
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, NY, USA
| | - Alexey Khodjakov
- New York State Department of Health, Wadsworth Center, Albany, NY, USA.,Rensselaer Polytechnic Institute, Troy, NY, USA
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21
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Single-Molecule Biophysical Techniques to Study Actomyosin Force Transduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020. [PMID: 32451857 DOI: 10.1007/978-3-030-38062-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Inside the cellular environment, molecular motors can work in concert to conduct a variety of important physiological functions and processes that are vital for the survival of a cell. However, in order to decipher the mechanism of how these molecular motors work, single-molecule microscopy techniques have been popular methods to understand the molecular basis of the emerging ensemble behavior of these motor proteins.In this chapter, we discuss various single-molecule biophysical imaging techniques that have been used to expose the mechanics and kinetics of myosins. The chapter should be taken as a general overview and introductory guide to the many existing techniques; however, since other chapters will discuss some of these techniques more thoroughly, the readership should refer to those chapters for further details and discussions. In particular, we will focus on scattering-based single-molecule microscopy methods, some of which have become more popular in the recent years and around which the work in our laboratories has been centered.
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22
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Tan SJ, Chang AC, Anderson SM, Miller CM, Prahl LS, Odde DJ, Dunn AR. Regulation and dynamics of force transmission at individual cell-matrix adhesion bonds. SCIENCE ADVANCES 2020; 6:eaax0317. [PMID: 32440534 PMCID: PMC7228748 DOI: 10.1126/sciadv.aax0317] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 03/05/2020] [Indexed: 05/22/2023]
Abstract
Integrin-based adhesion complexes link the cytoskeleton to the extracellular matrix (ECM) and are central to the construction of multicellular animal tissues. How biological function emerges from the tens to thousands of proteins present within a single adhesion complex remains unclear. We used fluorescent molecular tension sensors to visualize force transmission by individual integrins in living cells. These measurements revealed an underlying functional modularity in which integrin class controlled adhesion size and ECM ligand specificity, while the number and type of connections between integrins and F-actin determined the force per individual integrin. In addition, we found that most integrins existed in a state of near-mechanical equilibrium, a result not predicted by existing models of cytoskeletal force transduction. A revised model that includes reversible cross-links within the F-actin network can account for this result and suggests one means by which cellular mechanical homeostasis can arise at the molecular level.
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Affiliation(s)
- Steven J. Tan
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Alice C. Chang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Sarah M. Anderson
- Department of Biomedical Engineering and Physical Sciences–Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cayla M. Miller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Louis S. Prahl
- Department of Biomedical Engineering and Physical Sciences–Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - David J. Odde
- Department of Biomedical Engineering and Physical Sciences–Oncology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alexander R. Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Corresponding author.
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Roscioli E, Germanova TE, Smith CA, Embacher PA, Erent M, Thompson AI, Burroughs NJ, McAinsh AD. Ensemble-Level Organization of Human Kinetochores and Evidence for Distinct Tension and Attachment Sensors. Cell Rep 2020; 31:107535. [PMID: 32348762 PMCID: PMC7196887 DOI: 10.1016/j.celrep.2020.107535] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 02/10/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022] Open
Abstract
Kinetochores are multi-protein machines that form dynamic attachments to microtubules and control chromosome segregation. High fidelity is ensured because kinetochores can monitor attachment status and tension, using this information to activate checkpoints and error-correction mechanisms. To explore how kinetochores achieve this, we used two- and three-color subpixel fluorescence localization to define how proteins from six major complexes (CCAN, MIS12, NDC80, KNL1, RZZ, and SKA) and the checkpoint proteins Bub1, Mad1, and Mad2 are organized in the human kinetochore. This reveals how the outer kinetochore has a high nematic order and is largely invariant to the loss of attachment or tension, except for two mechanical sensors. First, Knl1 unravels to relay tension, and second, NDC80 undergoes jackknifing and loss of nematic order under microtubule detachment, with only the latter wired up to the checkpoint signaling system. This provides insight into how kinetochores integrate mechanical signals to promote error-free chromosome segregation.
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Affiliation(s)
- Emanuele Roscioli
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Tsvetelina E Germanova
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Christopher A Smith
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Peter A Embacher
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Mathematics Institute, University of Warwick, Coventry, UK
| | - Muriel Erent
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Amelia I Thompson
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Nigel J Burroughs
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Mathematics Institute, University of Warwick, Coventry, UK.
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK; Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
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24
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Qin X, Yoo H, Man Cheng HC, Nguyen QQ, Li J, Liu X, Prunetti L, Chen X, Liu T, Sweeney HL, Park H. Simultaneous tracking of two motor domains reveals near simultaneous steps and stutter steps of myosin 10 on actin filament bundles. Biochem Biophys Res Commun 2020; 525:S0006-291X(20)30305-3. [PMID: 32081426 PMCID: PMC7429334 DOI: 10.1016/j.bbrc.2020.02.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/06/2020] [Indexed: 11/30/2022]
Abstract
Myosin X (Myo10) has several unique design features including dimerization via an anti-parallel coiled coil and a long lever arm, which allow it to preferentially move on actin bundles. To understand the stepping behavior of single Myo10 on actin bundles, we labeled two heads of Myo10 dimers with different fluorophores. Unlike previously described for myosin V (Myo5) and VI (Myo6), which display alternating hand-over-hand stepping, Myo10 frequently took near simultaneous steps of both heads, and less frequently, 2-3 steps of one head before the other head stepped. We suggest that this behavior results from the unusual kinetic features of Myo10, in conjunction with the structural properties of the motor domain/lever arm, which will favor movement on actin bundles rather than on single filaments.
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Affiliation(s)
- Xianan Qin
- Department of Physics, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Hanna Yoo
- Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Harry Chun Man Cheng
- Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Quang Quan Nguyen
- Department of Physics, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Jing Li
- Department of Physics, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Xiaoyan Liu
- Department of Pharmacology and Therapeutics and the Myology Institute, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Laurence Prunetti
- Department of Pharmacology and Therapeutics and the Myology Institute, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Xingxiang Chen
- Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - Teng Liu
- Department of Physics, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong
| | - H Lee Sweeney
- Department of Pharmacology and Therapeutics and the Myology Institute, University of Florida College of Medicine, Gainesville, FL, 32610, USA.
| | - Hyokeun Park
- Department of Physics, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong; Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong.
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25
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Warning LA, Zhang Q, Baiyasi R, Landes CF, Link S. Nanoscale Surface-Induced Unfolding of Single Fibronectin Is Restricted by Serum Albumin Crowding. J Phys Chem Lett 2020; 11:1170-1177. [PMID: 31967479 DOI: 10.1021/acs.jpclett.9b03446] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Understanding nanoscale protein conformational changes at solid-liquid interfaces is critical for predicting how proteins will impact the performance of biomaterials in vivo. Crowding is an important contributor to conformational stability. Here we apply single-molecule high resolution imaging with photobleaching to directly measure dye-conjugated fibronectin's unfolding in varying conditions of crowding with human serum albumin on aminosilanized glass. Using this approach, we identify serum albumin's crowding mechanism. We find that fibronectin achieves larger degrees of unfolding when not crowded by coadsorbed serum albumin. Serum albumin does not as effectively constrict fibronectin's conformation if it is sequentially, rather than simultaneously, introduced, suggesting that serum albumin's crowding mechanism is dependent on its ability to sterically block fibronectin's unfolding during the process of adsorption. Because fibronectin's conformation is dependent on interfacial macromolecular crowding under in vitro conditions, it is important to consider the role of in vivo crowding on protein activity.
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26
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Furubayashi T, Ishida K, Kashida H, Nakata E, Morii T, Matsushita M, Fujiyoshi S. Nanometer Accuracy in Cryogenic Far-Field Localization Microscopy of Individual Molecules. J Phys Chem Lett 2019; 10:5841-5846. [PMID: 31525978 DOI: 10.1021/acs.jpclett.9b02184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We demonstrate the nanometer accuracy of far-field fluorescence localization microscopy at a temperature of 1.8 K using near-infrared and red fluorophores bonded to double-stranded DNA molecules (10.2 nm length). Although each fluorophore was localized with a 1 nm lateral precision by acquiring an image at one axial position within the focal depth of ±0.7 μm, the distance between the two fluorophores on the lateral plane (Dxy) was distributed from 0 to 50 nm. This systematic error was mainly due to detecting with the large focal depth the dipole emission from orientationally fixed fluorophores. Each fluorophore was localized with precisions of ±1 nm (lateral) and simultaneously ±11 nm (axial) by acquiring images every 100 nm in the axial direction from -900 to 900 nm. By correcting the dipole orientation effects, the distribution of Dxy was centered around the DNA length. The average and standard deviation of Dxy were 10 and 5 nm.
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Affiliation(s)
- Taku Furubayashi
- Department of Physics , Tokyo Institute of Technology , Meguro , Tokyo 152-8550 , Japan
| | - Keita Ishida
- Department of Physics , Tokyo Institute of Technology , Meguro , Tokyo 152-8550 , Japan
| | - Hiromu Kashida
- Graduate School of Engineering , Nagoya University , Chikusa, Nagoya 464-8603 , Japan
| | - Eiji Nakata
- Institute of Advanced Energy , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Takashi Morii
- Institute of Advanced Energy , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Michio Matsushita
- Department of Physics , Tokyo Institute of Technology , Meguro , Tokyo 152-8550 , Japan
| | - Satoru Fujiyoshi
- Department of Physics , Tokyo Institute of Technology , Meguro , Tokyo 152-8550 , Japan
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27
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Zhu M, Lu D, Wu S, Lian Q, Wang W, Lyon LA, Wang W, Bártolo P, Saunders BR. Using green emitting pH-responsive nanogels to report environmental changes within hydrogels: a nanoprobe for versatile sensing. NANOSCALE 2019; 11:11484-11495. [PMID: 31066411 DOI: 10.1039/c9nr00989b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Remotely reporting the local environment within hydrogels using inexpensive laboratory techniques has excellent potential to improve our understanding of the nanometer-scale changes that cause macroscopic swelling or deswelling. Whilst photoluminescence (PL) spectroscopy is a popular method for such studies this approach commonly requires bespoke and time-consuming synthesis to attach fluorophores which may leave toxic residues. A promising and more versatile alternative is to use a pre-formed nanogel probe that contains a donor/acceptor pair and then "dope" that into the gel during gel assembly. Here, we introduce green-emitting methacrylic acid-based nanogel probe particles and use them to report the local environment within four different gels as well as stem cells. As the swelling of the nanogel probe changes within the gels the non-radiative energy transfer efficiency is strongly altered. This efficiency change is sensitively reported using the PL ratiometric intensity from the donor and acceptor. We demonstrate that our new nanoprobes can reversibly report gel swelling changes due to five different environmental stimuli. The latter are divalent cations, gel degradation, pH changes, temperature changes and tensile strain. In the latter case, the nanoprobe rendered a nanocomposite gel mechanochromic. The results not only provide new structural insights for hierarchical natural and synthetic gels, but also demonstrate that our new green-fluorescing nanoprobes provide a viable alternative to custom fluorophore labelling for reporting the internal gel environment and its changes.
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Affiliation(s)
- Mingning Zhu
- School of Materials, University of Manchester, MSS Tower, Manchester, M13 9PL, UK.
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28
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Live-Cell Structural Biology to Solve Biological Mechanisms: The Case of the Exocyst. Structure 2019; 27:886-892. [DOI: 10.1016/j.str.2019.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/01/2019] [Accepted: 04/18/2019] [Indexed: 01/24/2023]
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29
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Taveras C, Liu C, Mao Y. A tension-independent mechanism reduces Aurora B-mediated phosphorylation upon microtubule capture by CENP-E at the kinetochore. Cell Cycle 2019; 18:1349-1363. [PMID: 31122175 DOI: 10.1080/15384101.2019.1617615] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
During mitosis, Aurora B kinase is required for forming proper bi-oriented kinetochore-microtubule attachments. Current models suggest that tension exerted between a pair of sister-kinetochores (inter-kinetochore stretch) produces a spatial separation of Aurora B kinase from kinetochore-associated microtubule binding substrates, such as the Knl1-Mis12-Ndc80 (KMN) network, resulting in a decrease of phosphorylation and, thus, an increase of affinity for microtubules. Using Single-Molecule High-Resolution Colocalization (SHREC) microscopy analysis of the kinetochore-associated motor CENP-E, we now show that CENP-E undergoes structural rearrangements prior to and after tension generation at the kinetochore, and displays a bi-modal Gaussian distribution on a pair of bi-oriented sister kinetochores. The conformational change of CENP-E depends on its microtubule-stimulated motor motility and the highly flexible coiled-coil between its motor and kinetochore-binding tail domains. Chemical inhibition of the motor motility or perturbations of the coiled-coil domain of CENP-E increases Aurora B-mediated Ndc80 phosphorylation in a tension-independent manner. Metaphase chromosome misalignment caused by CENP-E inhibition can be rescued by chemical inhibition of Aurora B kinase. Furthermore, a pair of monotelic sister-kinetochores shows asymmetric levels of Aurora B-mediated phosphorylation in mono-polar spindles depending on CENP-E motor activity. These results collectively suggest a tension-independent mechanism to reduce Aurora B-mediated phosphorylation of outer kinetochore components in response to microtubule capture by CENP-E.
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Affiliation(s)
- Carmen Taveras
- a Department of Pathology and Cell Biology , Columbia University Vagelos College of Physicians and Surgeons , New York , NY , USA
| | - Chenshu Liu
- a Department of Pathology and Cell Biology , Columbia University Vagelos College of Physicians and Surgeons , New York , NY , USA
| | - Yinghui Mao
- a Department of Pathology and Cell Biology , Columbia University Vagelos College of Physicians and Surgeons , New York , NY , USA
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30
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Laine RF, Tosheva KL, Gustafsson N, Gray RDM, Almada P, Albrecht D, Risa GT, Hurtig F, Lindås AC, Baum B, Mercer J, Leterrier C, Pereira PM, Culley S, Henriques R. NanoJ: a high-performance open-source super-resolution microscopy toolbox. JOURNAL OF PHYSICS D: APPLIED PHYSICS 2019; 52:163001. [PMID: 33191949 PMCID: PMC7655149 DOI: 10.1088/1361-6463/ab0261] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/09/2019] [Accepted: 01/28/2019] [Indexed: 05/18/2023]
Abstract
Super-resolution microscopy (SRM) has become essential for the study of nanoscale biological processes. This type of imaging often requires the use of specialised image analysis tools to process a large volume of recorded data and extract quantitative information. In recent years, our team has built an open-source image analysis framework for SRM designed to combine high performance and ease of use. We named it NanoJ-a reference to the popular ImageJ software it was developed for. In this paper, we highlight the current capabilities of NanoJ for several essential processing steps: spatio-temporal alignment of raw data (NanoJ-Core), super-resolution image reconstruction (NanoJ-SRRF), image quality assessment (NanoJ-SQUIRREL), structural modelling (NanoJ-VirusMapper) and control of the sample environment (NanoJ-Fluidics). We expect to expand NanoJ in the future through the development of new tools designed to improve quantitative data analysis and measure the reliability of fluorescent microscopy studies.
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Affiliation(s)
- Romain F Laine
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Kalina L Tosheva
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Nils Gustafsson
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- Centre for Mathematics and Physics in Life Sciences and Experimental Biology (CoMPLEX), University College London, London, United Kingdom
| | - Robert D M Gray
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- Centre for Mathematics and Physics in Life Sciences and Experimental Biology (CoMPLEX), University College London, London, United Kingdom
| | - Pedro Almada
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - David Albrecht
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Gabriel T Risa
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Fredrik Hurtig
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Ann-Christin Lindås
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Buzz Baum
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Jason Mercer
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Christophe Leterrier
- CNRS, INP, Institute of Neurophysiopathology, NeuroCyto, Aix-Marseille University, Marseille, France
| | - Pedro M Pereira
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Siân Culley
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Ricardo Henriques
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
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31
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Pitchiaya S, Mourao MDA, Jalihal AP, Xiao L, Jiang X, Chinnaiyan AM, Schnell S, Walter NG. Dynamic Recruitment of Single RNAs to Processing Bodies Depends on RNA Functionality. Mol Cell 2019; 74:521-533.e6. [PMID: 30952514 DOI: 10.1016/j.molcel.2019.03.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/21/2018] [Accepted: 02/27/2019] [Indexed: 11/19/2022]
Abstract
Cellular RNAs often colocalize with cytoplasmic, membrane-less ribonucleoprotein (RNP) granules enriched for RNA-processing enzymes, termed processing bodies (PBs). Here we track the dynamic localization of individual miRNAs, mRNAs, and long non-coding RNAs (lncRNAs) to PBs using intracellular single-molecule fluorescence microscopy. We find that unused miRNAs stably bind to PBs, whereas functional miRNAs, repressed mRNAs, and lncRNAs both transiently and stably localize within either the core or periphery of PBs, albeit to different extents. Consequently, translation potential and 3' versus 5' placement of miRNA target sites significantly affect the PB localization dynamics of mRNAs. Using computational modeling and supporting experimental approaches, we show that partitioning in the PB phase attenuates mRNA silencing, suggesting that physiological mRNA turnover occurs predominantly outside of PBs. Instead, our data support a PB role in sequestering unused miRNAs for surveillance and provide a framework for investigating the dynamic assembly of RNP granules by phase separation at single-molecule resolution.
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Affiliation(s)
- Sethuramasundaram Pitchiaya
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Marcio D A Mourao
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Consulting for Statistics, Computing and Analytics Research, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ameya P Jalihal
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Lanbo Xiao
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Xia Jiang
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Arul M Chinnaiyan
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Santiago Schnell
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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32
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Nanometer-accuracy distance measurements between fluorophores at the single-molecule level. Proc Natl Acad Sci U S A 2019; 116:4275-4284. [PMID: 30770448 PMCID: PMC6410877 DOI: 10.1073/pnas.1815826116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Measurements of macromolecular shapes provide insight into the mechanism of molecular machines. Distance measurements at the scale of biological macromolecules are often pursued by single-molecule fluorescence techniques. However, while single-molecule Förster resonance energy transfer can estimate distances of less than 8 nm, distances on the scale of 8 to 25 nm are difficult to determine. Here, we report two-color fluorescent distance measurement techniques capable of determining distances with ∼1-nm accuracy over a wide range of length scales. These methods can be implemented in high throughput on commonly available microscopes. As an example of their utility, we used our methods to uncover an unexpected conformational change in the antiparallel coiled-coil stalk of the dynein motor domain in different nucleotide states. Light microscopy is a powerful tool for probing the conformations of molecular machines at the single-molecule level. Single-molecule Förster resonance energy transfer can measure intramolecular distance changes of single molecules in the range of 2 to 8 nm. However, current superresolution measurements become error-prone below 25 nm. Thus, new single-molecule methods are needed for measuring distances in the 8- to 25-nm range. Here, we describe methods that utilize information about localization and imaging errors to measure distances between two different color fluorophores with ∼1-nm accuracy at distances >2 nm. These techniques can be implemented in high throughput using a standard total internal reflection fluorescence microscope and open-source software. We applied our two-color localization method to uncover an unexpected ∼4-nm nucleotide-dependent conformational change in the coiled-coil “stalk” of the motor protein dynein. We anticipate that these methods will be useful for high-accuracy distance measurements of single molecules over a wide range of length scales.
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33
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Yu Y, Gao Y, Yu Y. "Waltz" of Cell Membrane-Coated Nanoparticles on Lipid Bilayers: Tracking Single Particle Rotation in Ligand-Receptor Binding. ACS NANO 2018; 12:11871-11880. [PMID: 30421608 DOI: 10.1021/acsnano.8b04880] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Understanding the binding of nanoparticles to receptors on biomembranes is critical to the development and screening of therapeutic materials. A prevailing understanding is that multivalent ligand-receptor binding leads to slower and confined translational motion of nanoparticles. In contrast, we report in this study distinct types of rotational dynamics of nanoparticles during their seemingly similar translational confinements in ligand-receptor binding. Our nanoparticles are fluorescently anisotropic and camouflaged with T cell membranes. As they bind to ligands on planar lipid bilayers, the particles transition from back-and-forth rocking motion to circling and eventually confined circling motion, while "hopping" between translational confinements. Both rotational and translational motions of the nanoparticles become more confined at higher ligand density. The time-dependent changes in particle rotation reveal different stages in the progression of multivalent binding between the cell-membrane coated nanoparticles and their ligands. Our work also demonstrates the promise of using combined rotational and translational single particle tracking to resolve biological interactions that could be "hidden" in translational measurements alone.
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Affiliation(s)
- Yanqi Yu
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Yuan Gao
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Yan Yu
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
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34
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Olziersky AM, Smith CA, Burroughs N, McAinsh AD, Meraldi P. Mitotic live-cell imaging at different timescales. Methods Cell Biol 2018; 145:1-27. [PMID: 29957199 DOI: 10.1016/bs.mcb.2018.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitosis is a highly dynamic and choreographed process in which chromosomes are captured by the mitotic spindle and physically segregated into the two daughter cells to ensure faithful transmission of the genetic material. Live-cell fluorescence microscopy enables these dynamics to be analyzed over diverse temporal scales. Here we present the methodologies to study chromosome segregation at three timescales: we first show how automated tracking of kinetochores enables investigation of mitotic spindle and chromosome dynamics in the seconds-to-minutes timescale; next we highlight how new DNA live dyes allow the study of chromosome segregation over a period of several hours in any cell line; finally, we demonstrate how image sequences acquired over several days can reveal the fate of whole cell populations over several consecutive cell divisions.
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Affiliation(s)
- Anna-Maria Olziersky
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Chris A Smith
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Nigel Burroughs
- Mathematics Institute, University of Warwick, Coventry, United Kingdom
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology & Division of Biomedical Science, Warwick Medical School, University of Warwick, Coventry, United Kingdom.
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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35
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Laplante C. Building the contractile ring from the ground up: a lesson in perseverance and scientific creativity. Biophys Rev 2018; 10:1491-1497. [PMID: 30448942 DOI: 10.1007/s12551-018-0482-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 11/08/2018] [Indexed: 11/28/2022] Open
Abstract
This contribution to the Festschrift for Professor Thomas (Tom) D. Pollard focuses on his work on the elucidation of the protein organization within the cytokinetic nodes, protein assemblies, precursors to the contractile ring. In particular, this work highlights recent discoveries in the molecular organization of the proteins that make the contractile machine in fission yeast using advanced microscopy techniques. One of the main aspects of Tom's research philosophy that marked my career as one of his trainees is his embrace of interdisciplinary approaches to research. The cost of interdisciplinary research is to be willing to step out of our technical comfort zone to learn a new set of tools. The payoff of interdisciplinary research is the expansion our realm of possibilities by bringing new creative tools and ideas to push our research program forward. The rewarding outcomes of this work under Tom's mentorship were the molecular model of the cytokinetic node and the development of new techniques to unravel the structure of multi-protein complexes in live cells. Together, these findings open a new set of questions about the mechanism of cytokinesis and provide creative tools to address them.
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Affiliation(s)
- Caroline Laplante
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, 1051 William Moore Drive, Office: RB 254, Raleigh, NC, 27606, USA.
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36
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Abstract
The past decade has witnessed an explosion in the use of super-resolution fluorescence microscopy methods in biology and other fields. Single-molecule localization microscopy (SMLM) is one of the most widespread of these methods and owes its success in large part to the ability to control the on-off state of fluorophores through various chemical, photochemical, or binding-unbinding mechanisms. We provide here a comprehensive overview of switchable fluorophores in SMLM including a detailed review of all major classes of SMLM fluorophores, and we also address strategies for labeling specimens, considerations for multichannel and live-cell imaging, potential pitfalls, and areas for future development.
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Affiliation(s)
- Honglin Li
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA, 98195
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37
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Schmidt PD, Reichert BH, Lajoie JG, Sivasankar S. Method for high frequency tracking and sub-nm sample stabilization in single molecule fluorescence microscopy. Sci Rep 2018; 8:13912. [PMID: 30224660 PMCID: PMC6141618 DOI: 10.1038/s41598-018-32012-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 08/31/2018] [Indexed: 12/15/2022] Open
Abstract
While fluorescence microscopes and atomic force microscopes are widely used to visualize, track, and manipulate single biomolecules, the resolution of these methods is limited by sample drift. To minimize drift, active feedback methods have recently been used to stabilize single molecule microscopes on the sub-nanometer scale. However, these methods require high intensity lasers which limits their application in single molecule fluorescence measurements. Furthermore, these feedback methods do not track user-defined regions of the sample, but rather monitor the relative displacement of an unknown point on a fiducial marker, which limits their use in biological force measurements. To overcome these limitations, we have developed a novel method to image, track and stabilize a sample using low laser intensities. We demonstrate the capabilities of our approach by tracking a user-chosen point on a fiducial marker at 8.6 kHz and stabilizing it with sub-nanometer resolution. We further showcase the application of our method in single molecule fluorescence microscopy by imaging and stabilizing individual fluorescently-tagged streptavidin proteins under biologically relevant conditions. We anticipate that our method can be easily used to improve the resolution of a wide range of single molecule fluorescence microscopy and integrated force-fluorescence applications.
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Affiliation(s)
- Patrick D Schmidt
- Department of Electrical and Computer Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Benjamin H Reichert
- Department of Electrical and Computer Engineering, Iowa State University, Ames, IA, 50011, USA
| | - John G Lajoie
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
| | - Sanjeevi Sivasankar
- Department of Electrical and Computer Engineering, Iowa State University, Ames, IA, 50011, USA. .,Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA. .,Department of Biomedical Engineering, University of California, Davis, CA, 95616, USA.
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38
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Morales-Zavala F, Casanova-Morales N, Gonzalez RB, Chandía-Cristi A, Estrada LD, Alvizú I, Waselowski V, Guzman F, Guerrero S, Oyarzún-Olave M, Rebolledo C, Rodriguez E, Armijo J, Bhuyan H, Favre M, Alvarez AR, Kogan MJ, Maze JR. Functionalization of stable fluorescent nanodiamonds towards reliable detection of biomarkers for Alzheimer's disease. J Nanobiotechnology 2018; 16:60. [PMID: 30097010 PMCID: PMC6085760 DOI: 10.1186/s12951-018-0385-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/20/2018] [Indexed: 01/01/2023] Open
Abstract
Background Stable and non-toxic fluorescent markers are gaining attention in molecular diagnostics as powerful tools for enabling long and reliable biological studies. Such markers should not only have a long half-life under several assay conditions showing no photo bleaching or blinking but also, they must allow for their conjugation or functionalization as a crucial step for numerous applications such as cellular tracking, biomarker detection and drug delivery. Results We report the functionalization of stable fluorescent markers based on nanodiamonds (NDs) with a bifunctional peptide. This peptide is made of a cell penetrating peptide and a six amino acids long β-sheet breaker peptide that is able to recognize amyloid β (Aβ) aggregates, a biomarker for the Alzheimer disease. Our results indicate that functionalized NDs (fNDs) are not cytotoxic and can be internalized by the cells. The fNDs allow ultrasensitive detection (at picomolar concentrations of NDs) of in vitro amyloid fibrils and amyloid aggregates in AD mice brains. Conclusions The fluorescence of functionalized NDs is more stable than that of fluorescent markers commonly used to
stain Aβ aggregates such as Thioflavin T. These results pave the way for performing ultrasensitive and reliable detection of Aβ aggregates involved in the pathogenesis of the Alzheimer disease. Electronic supplementary material The online version of this article (10.1186/s12951-018-0385-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francisco Morales-Zavala
- Department of Pharmacological and Toxicological Chemistry, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Santiago, Chile
| | | | - Raúl B Gonzalez
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - América Chandía-Cristi
- Department of Cellular & Molecular Biology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Ignacio Alvizú
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Victor Waselowski
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Fanny Guzman
- Núcleo de Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Simón Guerrero
- Department of Pharmacological and Toxicological Chemistry, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Santiago, Chile
| | - Marisol Oyarzún-Olave
- Department of Cellular & Molecular Biology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cristian Rebolledo
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Enrique Rodriguez
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Julien Armijo
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile.,Centro de Investigación en Recursos Naturales y Sustentabilidad, Universidad Bernardo O'Higgins, Santiago, Chile
| | - Heman Bhuyan
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Mario Favre
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile
| | - Alejandra R Alvarez
- Department of Cellular & Molecular Biology, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Center for Nanoscale Technology and Advanced Materials, Pontificia Universidad Catolica de Chile, Santiago, Chile. .,CARE-Chile-UC, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Marcelo J Kogan
- Department of Pharmacological and Toxicological Chemistry, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile. .,Advanced Center for Chronic Diseases (ACCDiS), Santiago, Chile.
| | - Jerónimo R Maze
- Institute of Physics, Pontificia Universidad Católica de Chile, Santiago, 7820436, Chile. .,Center for Nanoscale Technology and Advanced Materials, Pontificia Universidad Catolica de Chile, Santiago, Chile.
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Krishnamurthy VV, Zhang K. Chemical physics in living cells — Using light to visualize and control intracellular signal transduction. CHINESE J CHEM PHYS 2018. [DOI: 10.1063/1674-0068/31/cjcp1806152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Vishnu V. Krishnamurthy
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Kai Zhang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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40
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Accurate and fiducial-marker-free correction for three-dimensional chromatic shift in biological fluorescence microscopy. Sci Rep 2018; 8:7583. [PMID: 29765093 PMCID: PMC5954143 DOI: 10.1038/s41598-018-25922-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/02/2018] [Indexed: 11/09/2022] Open
Abstract
Correction of chromatic shift is necessary for precise registration of multicolor fluorescence images of biological specimens. New emerging technologies in fluorescence microscopy with increasing spatial resolution and penetration depth have prompted the need for more accurate methods to correct chromatic aberration. However, the amount of chromatic shift of the region of interest in biological samples often deviates from the theoretical prediction because of unknown dispersion in the biological samples. To measure and correct chromatic shift in biological samples, we developed a quadrisection phase correlation approach to computationally calculate translation, rotation, and magnification from reference images. Furthermore, to account for local chromatic shifts, images are split into smaller elements, for which the phase correlation between channels is measured individually and corrected accordingly. We implemented this method in an easy-to-use open-source software package, called Chromagnon, that is able to correct shifts with a 3D accuracy of approximately 15 nm. Applying this software, we quantified the level of uncertainty in chromatic shift correction, depending on the imaging modality used, and for different existing calibration methods, along with the proposed one. Finally, we provide guidelines to choose the optimal chromatic shift registration method for any given situation.
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41
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Zettl T, Mathew RS, Shi X, Doniach S, Herschlag D, Harbury PAB, Lipfert J. Gold nanocrystal labels provide a sequence-to-3D structure map in SAXS reconstructions. SCIENCE ADVANCES 2018; 4:eaar4418. [PMID: 29806025 PMCID: PMC5969820 DOI: 10.1126/sciadv.aar4418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 04/17/2018] [Indexed: 06/08/2023]
Abstract
Small-angle x-ray scattering (SAXS) is a powerful technique to probe the structure of biological macromolecules and their complexes under virtually arbitrary solution conditions, without the need for crystallization. While it is possible to reconstruct molecular shapes from SAXS data ab initio, the resulting electron density maps have a resolution of ~1 nm and are often insufficient to reliably assign secondary structure elements or domains. We show that SAXS data of gold-labeled samples significantly enhance the information content of SAXS measurements, allowing the unambiguous assignment of macromolecular sequence motifs to specific locations within a SAXS structure. We first demonstrate our approach for site-specifically internally and end-labeled DNA and an RNA motif. In addition, we present a protocol for highly uniform and site-specific labeling of proteins with small (~1.4 nm diameter) gold particles and apply our method to the signaling protein calmodulin. In all cases, the position of the small gold probes can be reliably identified in low-resolution electron density maps. Enhancing low-resolution measurements by site-selective gold labeling provides an attractive approach to aid modeling of a large range of macromolecular systems.
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Affiliation(s)
- Thomas Zettl
- Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience, LMU Munich, Munich, Germany
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Rebecca S. Mathew
- Department of Cell Biology, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Xuesong Shi
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Sebastian Doniach
- Departments of Applied Physics and Physics, Stanford University, Stanford, CA 94305, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Pehr A. B. Harbury
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Jan Lipfert
- Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience, LMU Munich, Munich, Germany
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42
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Maurice L, Bilenca A. Maximum-likelihood analysis of axial displacement in fluorescence phase-shifting interferometry. OPTICS EXPRESS 2018; 26:7965-7978. [PMID: 29715771 DOI: 10.1364/oe.26.007965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
Fluorescence phase-shifting interferometry (FPSI) is an optical technique that coherently combines the phase-shifted 4π steradian emission wavefronts of a single fluorescent emitter to obtain multiple interferograms from which the emitter axial displacement can be retrieved with high precision. Here, we study the axial displacement sensitivity in 4-step FPSI within the framework of maximum-likelihood (ML) phase estimation. Using Monte-Carlo simulations, we show that regardless of the method used to preprocess the measured interferograms, the variance of the ML estimate of the axial displacement approaches the Cramér-Rao lower bound and is closely limited from above by the variance of the classical 4-step phase shifting estimator. The difference between these lower and upper bounds depends on the interferogram visibility and signal-to-noise-ratio (SNR), with a percentage change of up to 29% that yields an absolute change of a few sub-nanometers to some nanometers for SNRs larger than ~5. Our results suggest that for these levels of SNR, the use of the computationally simpler classical 4-step phase shifting estimation can be adequate to accurately determine axial displacements in FPSI, as we also experimentally verified. FPSI interferograms with lower SNR but good visibility can benefit from the use of the ML estimator, provided that the spatiotemporal phase stability of the FPSI system is high.
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Frederickx W, Rocha S, Fujita Y, Kennes K, De Keersmaecker H, De Feyter S, Uji-I H, Vanderlinden W. Orthogonal Probing of Single-Molecule Heterogeneity by Correlative Fluorescence and Force Microscopy. ACS NANO 2018; 12:168-177. [PMID: 29257876 DOI: 10.1021/acsnano.7b05405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Correlative imaging by fluorescence and force microscopy is an emerging technology to acquire orthogonal information at the nanoscale. Whereas atomic force microscopy excels at resolving the envelope structure of nanoscale specimens, fluorescence microscopy can detect specific molecular labels, which enables the unambiguous recognition of molecules in a complex assembly. Whereas correlative imaging at the micrometer scale has been established, it remains challenging to push the technology to the single-molecule level. Here, we used an integrated setup to systematically evaluate the factors that influence the quality of correlative fluorescence and force microscopy. Optimized data processing to ensure accurate drift correction and high localization precision results in image registration accuracies of ∼25 nm on organic fluorophores, which represents a 2-fold improvement over the state of the art in correlative fluorescence and force microscopy. Furthermore, we could extend the Atto532 fluorophore bleaching time ∼2-fold, by chemical modification of the supporting mica surface. In turn, this enables probing the composition of macromolecular complexes by stepwise photobleaching with high confidence. We demonstrate the performance of our method by resolving the stoichiometry of molecular subpopulations in a heterogeneous EcoRV-DNA nucleoprotein ensemble.
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Affiliation(s)
- Wout Frederickx
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Susana Rocha
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Yasuhiko Fujita
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Koen Kennes
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Herlinde De Keersmaecker
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Steven De Feyter
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Hiroshi Uji-I
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
- Research Institute for Electronic Science, Nanomaterials and Nanoscopy, Hokkaido University , Kita 10 Nishi 20, North Ward, Sapporo 001-0020, Japan
| | - Willem Vanderlinden
- Department of Chemistry, Division of Molecular Imaging and Photonics, KU Leuven-University of Leuven , Celestijnenlaan 200F, B-3001, Leuven, Belgium
- Department of Physics, Nanosystems Initiative Munich, and Center for NanoScience, LMU Munich , Amalienstrasse 54, 80799 Munich, Germany
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44
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Suzuki A, Long SK, Salmon ED. An optimized method for 3D fluorescence co-localization applied to human kinetochore protein architecture. eLife 2018; 7:32418. [PMID: 29323636 PMCID: PMC5764572 DOI: 10.7554/elife.32418] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/22/2017] [Indexed: 12/13/2022] Open
Abstract
Two-color fluorescence co-localization in 3D (three-dimension) has the potential to achieve accurate measurements at the nanometer length scale. Here, we optimized a 3D fluorescence co-localization method that uses mean values for chromatic aberration correction to yield the mean separation with ~10 nm accuracy between green and red fluorescently labeled protein epitopes within single human kinetochores. Accuracy depended critically on achieving small standard deviations in fluorescence centroid determination, chromatic aberration across the measurement field, and coverslip thickness. Computer simulations showed that large standard deviations in these parameters significantly increase 3D measurements from their true values. Our 3D results show that at metaphase, the protein linkage between CENP-A within the inner kinetochore and the microtubule-binding domain of the Ndc80 complex within the outer kinetochore is on average ~90 nm. The Ndc80 complex appears fully extended at metaphase and exhibits the same subunit structure in vivo as found in vitro by crystallography.
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Affiliation(s)
- Aussie Suzuki
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Sarah K Long
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Edward D Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
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45
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De Keersmaecker H, Frederickx W, Fujita Y, De Feyter S, Uji-I H, Rocha S, Vanderlinden W. Correlative Atomic Force and Single-Molecule Fluorescence Microscopy of Nucleoprotein Complexes. Methods Mol Biol 2018; 1814:339-359. [PMID: 29956242 DOI: 10.1007/978-1-4939-8591-3_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Correlative imaging by fluorescence and atomic force microscopy provides a versatile tool to extract orthogonal information on structurally heterogeneous biomolecular assemblies. In this chapter, we describe an integrated setup for correlative fluorescence and force microscopy. We present factors influencing data quality, as well as step-by-step protocols for sample preparation, data acquisition, and data processing that yield nanoscale topographic resolution, high image registration accuracy, and single-fluorophore sensitivity. We demonstrate the capabilities of the approach through simultaneous characterization of mesoscale geometry and composition in a multipart nucleoprotein complex.
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Affiliation(s)
- Herlinde De Keersmaecker
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
| | - Wout Frederickx
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
| | - Yasuhiko Fujita
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
| | - Steven De Feyter
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
| | - Hiroshi Uji-I
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
- Research Institute for Electronic Science, Nanomaterials and Nanoscopy, Hokkaido University, Sapporo, Japan
| | - Susana Rocha
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium
| | - Willem Vanderlinden
- Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven, Leuven, Belgium.
- Department of Physics, Nanosystems Initiative Munich, and Center for NanoScience, LMU Munich, Munich, Germany.
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46
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Abstract
Here, we describe protocols for three-dimensional tracking of single quantum dot-conjugated molecules with nanometer accuracy in living cells using conventional fluorescence microscopy. The technique exploits out-of-focus images of single emitters combined with an automated pattern-recognition open-source software that fits the images with proper model functions to extract the emitter coordinates. We describe protocols for targeting quantum dots to both membrane components and cytosolic proteins.
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47
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van den Wildenberg SMJL, Prevo B, Peterman EJG. A Brief Introduction to Single-Molecule Fluorescence Methods. Methods Mol Biol 2018; 1665:93-113. [PMID: 28940065 DOI: 10.1007/978-1-4939-7271-5_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which will be the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also allow access to useful measurable parameters on time and length scales relevant for the biomolecular world. Before several detailed experimental approaches will be addressed, we will first give a general overview of single-molecule fluorescence microscopy. We start with discussing the phenomenon of fluorescence in general and the history of single-molecule fluorescence microscopy. Next, we will review fluorescent probes in more detail and the equipment required to visualize them on the single-molecule level. We will end with a description of parameters measurable with such approaches, ranging from protein counting and tracking, single-molecule localization super-resolution microscopy, to distance measurements with Förster Resonance Energy Transfer and orientation measurements with fluorescence polarization.
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Affiliation(s)
- Siet M J L van den Wildenberg
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
- Équipe de Volcanologie, Observatoire de Physique de Globe, Clermant-Ferrand, France
| | - Bram Prevo
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Erwin J G Peterman
- LaserLaB and Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
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48
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Pasulka AL, Thamatrakoln K, Kopf SH, Guan Y, Poulos B, Moradian A, Sweredoski MJ, Hess S, Sullivan MB, Bidle KD, Orphan VJ. Interrogating marine virus-host interactions and elemental transfer with BONCAT and nanoSIMS-based methods. Environ Microbiol 2017; 20:671-692. [DOI: 10.1111/1462-2920.13996] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/10/2017] [Accepted: 11/12/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Alexis L. Pasulka
- Division of Geological and Planetary Sciences; California Institute of Technology; CA USA
| | | | - Sebastian H. Kopf
- Department of Geological Sciences, University of Colorado Boulder; CO USA
| | - Yunbin Guan
- Division of Geological and Planetary Sciences; California Institute of Technology; CA USA
| | - Bonnie Poulos
- Department of Ecology and Evolutionary Biology, University of Arizona; AZ USA
| | - Annie Moradian
- Proteome Exploration Laboratory, California Institute of Technology; CA USA
| | | | - Sonja Hess
- Proteome Exploration Laboratory, California Institute of Technology; CA USA
| | | | - Kay D. Bidle
- Department of Marine and Coastal Studies; Rutgers University; NJ USA
| | - Victoria J. Orphan
- Division of Geological and Planetary Sciences; California Institute of Technology; CA USA
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49
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Measuring Nanometer Distances Between Fluorescent Labels Step-by-Step. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2017; 1663:189-203. [PMID: 28924669 DOI: 10.1007/978-1-4939-7265-4_16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Super-resolution fluorescence microscopy methods are increasingly applied to study the structure of biological molecules within their natural context or at biomaterial interfaces. We here provide a protocol for Single-molecule High-Resolution Imaging with Photobleaching (SHRImP) that can be used to obtain information about the conformation of large proteins or other macromolecules at the single-molecule level. This procedure requires site-specific protein labeling with fluorescent dyes, immobilization and sample preparation, optimization of imaging buffer composition and microscope settings, and acquisition of short time-lapse movies that capture the stepwise bleaching behavior of individual molecules. We then describe a method for reliably determining the relative positions of labels from bleaching movies using the free image processing package Fiji (ImageJ) with the help of auxiliary macros that are provided as Supplementary Material. The presented approach allows for measuring intramolecular distance distributions in the range of a few to hundreds of nanometers and can be applied to a wide variety of biological systems.
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50
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Owen LM, Adhikari AS, Patel M, Grimmer P, Leijnse N, Kim MC, Notbohm J, Franck C, Dunn AR. A cytoskeletal clutch mediates cellular force transmission in a soft, three-dimensional extracellular matrix. Mol Biol Cell 2017; 28:1959-1974. [PMID: 28592635 PMCID: PMC5541846 DOI: 10.1091/mbc.e17-02-0102] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/26/2017] [Accepted: 05/31/2017] [Indexed: 01/08/2023] Open
Abstract
The ability of cells to impart forces and deformations on their surroundings underlies cell migration and extracellular matrix (ECM) remodeling and is thus an essential aspect of complex, metazoan life. Previous work has resulted in a refined understanding, commonly termed the molecular clutch model, of how cells adhering to flat surfaces such as a microscope coverslip transmit cytoskeletally generated forces to their surroundings. Comparatively less is known about how cells adhere to and exert forces in soft, three-dimensional (3D), and structurally heterogeneous ECM environments such as occur in vivo. We used time-lapse 3D imaging and quantitative image analysis to determine how the actin cytoskeleton is mechanically coupled to the surrounding matrix for primary dermal fibroblasts embedded in a 3D fibrin matrix. Under these circumstances, the cytoskeletal architecture is dominated by contractile actin bundles attached at their ends to large, stable, integrin-based adhesions. Time-lapse imaging reveals that α-actinin-1 puncta within actomyosin bundles move more quickly than the paxillin-rich adhesion plaques, which in turn move more quickly than the local matrix, an observation reminiscent of the molecular clutch model. However, closer examination did not reveal a continuous rearward flow of the actin cytoskeleton over slower moving adhesions. Instead, we found that a subset of stress fibers continuously elongated at their attachment points to integrin adhesions, providing stable, yet structurally dynamic coupling to the ECM. Analytical modeling and numerical simulation provide a plausible physical explanation for this result and support a picture in which cells respond to the effective stiffness of local matrix attachment points. The resulting dynamic equilibrium can explain how cells maintain stable, contractile connections to discrete points within ECM during cell migration, and provides a plausible means by which fibroblasts contract provisional matrices during wound healing.
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Affiliation(s)
- Leanna M Owen
- Biophysics, Stanford University, Stanford, CA 94305
- Chemical Engineering, Stanford University, Stanford, CA 94305
| | | | - Mohak Patel
- School of Engineering, Brown University, Providence, RI 02912
| | - Peter Grimmer
- Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53711
| | | | - Min Cheol Kim
- Chemical Engineering, Stanford University, Stanford, CA 94305
| | - Jacob Notbohm
- Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53711
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