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Winkelmann H, Richter CP, Eising J, Piehler J, Kurre R. Correlative single-molecule and structured illumination microscopy of fast dynamics at the plasma membrane. Nat Commun 2024; 15:5813. [PMID: 38987559 PMCID: PMC11236984 DOI: 10.1038/s41467-024-49876-9] [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] [Received: 09/25/2023] [Accepted: 06/21/2024] [Indexed: 07/12/2024] Open
Abstract
Total internal reflection fluorescence (TIRF) microscopy offers powerful means to uncover the functional organization of proteins in the plasma membrane with very high spatial and temporal resolution. Traditional TIRF illumination, however, shows a Gaussian intensity profile, which is typically deteriorated by overlaying interference fringes hampering precise quantification of intensities-an important requisite for quantitative analyses in single-molecule localization microscopy (SMLM). Here, we combine flat-field illumination by using a standard πShaper with multi-angular TIR illumination by incorporating a spatial light modulator compatible with fast super-resolution structured illumination microscopy (SIM). This distinct combination enables quantitative multi-color SMLM with a highly homogenous illumination. By using a dual camera setup with optimized image splitting optics, we achieve a versatile combination of SMLM and SIM with up to three channels. We deploy this setup for establishing robust detection of receptor stoichiometries based on single-molecule intensity analysis and single-molecule Förster resonance energy transfer (smFRET). Homogeneous illumination furthermore enables long-term tracking and localization microscopy (TALM) of cell surface receptors identifying spatial heterogeneity of mobility and accessibility in the plasma membrane. By combination of TALM and SIM, spatially and molecularly heterogenous diffusion properties can be correlated with nanoscale cytoskeletal organization and dynamics.
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Affiliation(s)
- Hauke Winkelmann
- Division of Biophysics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany
| | - Christian P Richter
- Division of Biophysics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany
| | - Jasper Eising
- Division of Biophysics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany
| | - Jacob Piehler
- Division of Biophysics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany.
- Center for Cellular Nanoanalytics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany.
| | - Rainer Kurre
- Division of Biophysics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany.
- Center for Cellular Nanoanalytics, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany.
- Integrated Bioimaging Facility iBiOs, Department of Biology/Chemistry, Osnabrück University, Barbarastraße 11, D-49076, Osnabrück, Germany.
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2
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Middlemiss S, Blandenet M, Roberts DM, McMahon A, Grimshaw J, Edwards JM, Sun Z, Whitley KD, Blu T, Strahl H, Holden S. Molecular motor tug-of-war regulates elongasome cell wall synthesis dynamics in Bacillus subtilis. Nat Commun 2024; 15:5411. [PMID: 38926336 PMCID: PMC11208587 DOI: 10.1038/s41467-024-49785-x] [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] [Received: 05/10/2023] [Accepted: 06/18/2024] [Indexed: 06/28/2024] Open
Abstract
Most rod-shaped bacteria elongate by inserting new cell wall material into the inner surface of the cell sidewall. This is performed by class A penicillin binding proteins (PBPs) and a highly conserved protein complex, the elongasome, which moves processively around the cell circumference and inserts long glycan strands that act as barrel-hoop-like reinforcing structures, thereby giving rise to a rod-shaped cell. However, it remains unclear how elongasome synthesis dynamics and termination events are regulated to determine the length of these critical cell-reinforcing structures. To address this, we developed a method to track individual elongasome complexes around the entire circumference of Bacillus subtilis cells for minutes-long periods using single-molecule fluorescence microscopy. We found that the B. subtilis elongasome is highly processive and that processive synthesis events are frequently terminated by rapid reversal or extended pauses. We found that cellular levels of RodA regulate elongasome processivity, reversal and pausing. Our single-molecule data, together with stochastic simulations, show that elongasome dynamics and processivity are regulated by molecular motor tug-of-war competition between several, likely two, oppositely oriented peptidoglycan synthesis complexes associated with the MreB filament. Altogether these results demonstrate that molecular motor tug-of-war is a key regulator of elongasome dynamics in B. subtilis, which likely also regulates the cell shape via modulation of elongasome processivity.
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Affiliation(s)
- Stuart Middlemiss
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - Matthieu Blandenet
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - David M Roberts
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - Andrew McMahon
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - James Grimshaw
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Joshua M Edwards
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - Zikai Sun
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Kevin D Whitley
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Thierry Blu
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
- Dept of Electrical Engineering, National Taiwan University, Taipei City, Taiwan
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - Séamus Holden
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK.
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3
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Nelson T, Vargas-Hernández S, Freire M, Cheng S, Gustavsson AK. Multimodal illumination platform for 3D single-molecule super-resolution imaging throughout mammalian cells. BIOMEDICAL OPTICS EXPRESS 2024; 15:3050-3063. [PMID: 38855669 PMCID: PMC11161355 DOI: 10.1364/boe.521362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/22/2024] [Accepted: 03/24/2024] [Indexed: 06/11/2024]
Abstract
Single-molecule super-resolution imaging is instrumental in investigating cellular architecture and organization at the nanoscale. Achieving precise 3D nanometric localization when imaging structures throughout mammalian cells, which can be multiple microns thick, requires careful selection of the illumination scheme in order to optimize the fluorescence signal to background ratio (SBR). Thus, an optical platform that combines different wide-field illumination schemes for target-specific SBR optimization would facilitate more precise 3D nanoscale studies of a wide range of cellular structures. Here, we demonstrate a versatile multimodal illumination platform that integrates the sectioning and background reduction capabilities of light sheet illumination with homogeneous, flat-field epi- and TIRF illumination. Using primarily commercially available parts, we combine the fast and convenient switching between illumination modalities with point spread function engineering to enable 3D single-molecule super-resolution imaging throughout mammalian cells. For targets directly at the coverslip, the homogenous intensity profile and excellent sectioning of our flat-field TIRF illumination scheme improves single-molecule data quality by providing low fluorescence background and uniform fluorophore blinking kinetics, fluorescence signal, and localization precision across the entire field of view. The increased contrast achieved with LS illumination, when compared with epi-illumination, makes this illumination modality an excellent alternative when imaging targets that extend throughout the cell. We validate our microscopy platform for improved 3D super-resolution imaging by two-color imaging of paxillin - a protein located in the focal adhesion complex - and actin in human osteosarcoma cells.
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Affiliation(s)
- Tyler Nelson
- Department of Chemistry, Rice University, 6100 Main St, Houston, TX 77005, USA
- Applied Physics Program, Rice University, 6100 Main St, Houston, TX 77005, USA
- Smalley-Curl Institute, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Sofía Vargas-Hernández
- Department of Chemistry, Rice University, 6100 Main St, Houston, TX 77005, USA
- Systems, Synthetic, and Physical Biology Program, Rice University, 6100 Main St, Houston, TX 77005, USA
- Institute of Biosciences & Bioengineering, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Margareth Freire
- Department of Chemistry, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Siyang Cheng
- Department of Chemistry, Rice University, 6100 Main St, Houston, TX 77005, USA
- Applied Physics Program, Rice University, 6100 Main St, Houston, TX 77005, USA
- Smalley-Curl Institute, Rice University, 6100 Main St, Houston, TX 77005, USA
| | - Anna-Karin Gustavsson
- Department of Chemistry, Rice University, 6100 Main St, Houston, TX 77005, USA
- Smalley-Curl Institute, Rice University, 6100 Main St, Houston, TX 77005, USA
- Institute of Biosciences & Bioengineering, Rice University, 6100 Main St, Houston, TX 77005, USA
- Department of Biosciences, Rice University, 6100 Main St, Houston, TX 77005, USA
- Department of Electrical and Computer Engineering, Rice University, 6100 Main St, Houston, TX 77005, USA
- Center for Nanoscale Imaging Sciences, Rice University, 6100 Main St, Houston, TX 77005, USA
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA
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4
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Whitley KD, Grimshaw J, Roberts DM, Karinou E, Stansfeld PJ, Holden S. Peptidoglycan synthesis drives a single population of septal cell wall synthases during division in Bacillus subtilis. Nat Microbiol 2024; 9:1064-1074. [PMID: 38480901 PMCID: PMC10994842 DOI: 10.1038/s41564-024-01650-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/23/2024] [Indexed: 04/06/2024]
Abstract
Bacterial cell division requires septal peptidoglycan (sPG) synthesis by the divisome complex. Treadmilling of the essential tubulin homologue FtsZ has been implicated in septal constriction, though its precise role remains unclear. Here we used live-cell single-molecule imaging of the divisome transpeptidase PBP2B to investigate sPG synthesis dynamics in Bacillus subtilis. In contrast to previous models, we observed a single population of processively moving PBP2B molecules whose motion is driven by peptidoglycan synthesis and is not associated with FtsZ treadmilling. However, despite the asynchronous motions of PBP2B and FtsZ, a partial dependence of PBP2B processivity on FtsZ treadmilling was observed. Additionally, through single-molecule counting experiments we provide evidence that the divisome synthesis complex is multimeric. Our results support a model for B. subtilis division where a multimeric synthesis complex follows a single track dependent on sPG synthesis whose activity and dynamics are asynchronous with FtsZ treadmilling.
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Affiliation(s)
- Kevin D Whitley
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - James Grimshaw
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - David M Roberts
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Eleni Karinou
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Phillip J Stansfeld
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Séamus Holden
- School of Life Sciences, University of Warwick, Coventry, UK.
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5
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Super-Resolution Microscopy and Their Applications in Food Materials: Beyond the Resolution Limits of Fluorescence Microscopy. FOOD BIOPROCESS TECH 2022. [DOI: 10.1007/s11947-022-02883-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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6
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Spahn C, Gómez-de-Mariscal E, Laine RF, Pereira PM, von Chamier L, Conduit M, Pinho MG, Jacquemet G, Holden S, Heilemann M, Henriques R. DeepBacs for multi-task bacterial image analysis using open-source deep learning approaches. Commun Biol 2022; 5:688. [PMID: 35810255 PMCID: PMC9271087 DOI: 10.1038/s42003-022-03634-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 06/23/2022] [Indexed: 11/09/2022] Open
Abstract
This work demonstrates and guides how to use a range of state-of-the-art artificial neural-networks to analyse bacterial microscopy images using the recently developed ZeroCostDL4Mic platform. We generated a database of image datasets used to train networks for various image analysis tasks and present strategies for data acquisition and curation, as well as model training. We showcase different deep learning (DL) approaches for segmenting bright field and fluorescence images of different bacterial species, use object detection to classify different growth stages in time-lapse imaging data, and carry out DL-assisted phenotypic profiling of antibiotic-treated cells. To also demonstrate the ability of DL to enhance low-phototoxicity live-cell microscopy, we showcase how image denoising can allow researchers to attain high-fidelity data in faster and longer imaging. Finally, artificial labelling of cell membranes and predictions of super-resolution images allow for accurate mapping of cell shape and intracellular targets. Our purposefully-built database of training and testing data aids in novice users' training, enabling them to quickly explore how to analyse their data through DL. We hope this lays a fertile ground for the efficient application of DL in microbiology and fosters the creation of tools for bacterial cell biology and antibiotic research.
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Affiliation(s)
- Christoph Spahn
- Department of Natural Products in Organismic Interaction, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany.
| | | | - Romain F Laine
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK
- The Francis Crick Institute, London, UK
- Micrographia Bio, Translation and Innovation hub 84 Wood lane, W120BZ, London, UK
| | - Pedro M Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lucas von Chamier
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Mia Conduit
- Centre for Bacterial Cell Biology, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne, NE24AX, United Kingdom
| | - Mariana G Pinho
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Guillaume Jacquemet
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
- Turku Bioimaging, University of Turku and Åbo Akademi University, Turku, Finland
| | - Séamus Holden
- Centre for Bacterial Cell Biology, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne, NE24AX, United Kingdom
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany.
| | - Ricardo Henriques
- Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal.
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK.
- The Francis Crick Institute, London, UK.
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7
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Hobson CM, Aaron JS. Combining multiple fluorescence imaging techniques in biology: when one microscope is not enough. Mol Biol Cell 2022; 33:tp1. [PMID: 35549314 PMCID: PMC9265156 DOI: 10.1091/mbc.e21-10-0506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/16/2021] [Accepted: 11/29/2021] [Indexed: 11/11/2022] Open
Abstract
While fluorescence microscopy has proven to be an exceedingly useful tool in bioscience, it is difficult to offer simultaneous high resolution, fast speed, large volume, and good biocompatibility in a single imaging technique. Thus, when determining the image data required to quantitatively test a complex biological hypothesis, it often becomes evident that multiple imaging techniques are necessary. Recent years have seen an explosion in development of novel fluorescence microscopy techniques, each of which features a unique suite of capabilities. In this Technical Perspective, we highlight recent studies to illustrate the benefits, and often the necessity, of combining multiple fluorescence microscopy modalities. We provide guidance in choosing optimal technique combinations to effectively address a biological question. Ultimately, we aim to promote a more well-rounded approach in designing fluorescence microscopy experiments, leading to more robust quantitative insight.
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Affiliation(s)
- Chad M. Hobson
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Jesse S. Aaron
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
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8
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Whitley KD, Middlemiss S, Jukes C, Dekker C, Holden S. High-resolution imaging of bacterial spatial organization with vertical cell imaging by nanostructured immobilization (VerCINI). Nat Protoc 2022; 17:847-869. [DOI: 10.1038/s41596-021-00668-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/19/2021] [Indexed: 11/09/2022]
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9
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Dynes JL, Yeromin AV, Cahalan MD. Cell-wide mapping of Orai1 channel activity reveals functional heterogeneity in STIM1-Orai1 puncta. J Gen Physiol 2021; 152:151900. [PMID: 32589186 PMCID: PMC7478869 DOI: 10.1085/jgp.201812239] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 12/11/2019] [Accepted: 05/21/2020] [Indexed: 12/16/2022] Open
Abstract
Upon Ca2+ store depletion, Orai1 channels cluster and open at endoplasmic reticulum–plasma membrane (ER–PM) junctions in signaling complexes called puncta. Little is known about whether and how Orai1 channel activity may vary between individual puncta. Previously, we developed and validated optical recording of Orai channel activity, using genetically encoded Ca2+ indicators fused to Orai1 or Orai3 N or C termini. We have now combined total internal reflection fluorescence microscopy with whole-cell recording to map functional properties of channels at individual puncta. After Ca2+ store depletion in HEK cells cotransfected with mCherry-STIM1 and Orai1-GCaMP6f, Orai1-GCaMP6f fluorescence increased progressively with increasingly negative test potentials and robust responses could be recorded from individual puncta. Cell-wide fluorescence half-rise and -fall times during steps to −100 mV test potential indicated probe response times of <50 ms. The in situ Orai1-GCaMP6f affinity for Ca2+ was 620 nM, assessed by monitoring fluorescence using buffered Ca2+ solutions in “unroofed” cells. Channel activity and temporal activation profile were tracked in individual puncta using image maps and automated puncta identification and recording. Simultaneous measurement of mCherry-STIM1 fluorescence uncovered an unexpected gradient in STIM1/Orai1 ratio that extends across the cell surface. Orai1-GCaMP6f channel activity was found to vary across the cell, with inactive channels occurring in the corners of cells where the STIM1/Orai1 ratio was lowest; low-activity channels typically at edges displayed a slow activation phase lasting hundreds of milliseconds. Puncta with high STIM1/Orai1 ratios exhibited a range of channel activity that appeared unrelated to the stoichiometric requirements for gating. These findings demonstrate functional heterogeneity of Orai1 channel activity between individual puncta and establish a new experimental platform that facilitates systematic comparisons between puncta composition and activity.
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Affiliation(s)
- Joseph L Dynes
- Department of Physiology and Biophysics, University of California at Irvine School of Medicine, Irvine, CA
| | - Andriy V Yeromin
- Department of Physiology and Biophysics, University of California at Irvine School of Medicine, Irvine, CA
| | - Michael D Cahalan
- Department of Physiology and Biophysics, University of California at Irvine School of Medicine, Irvine, CA.,Institute for Immunology, University of California, Irvine, Irvine, CA
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10
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FtsZ treadmilling is essential for Z-ring condensation and septal constriction initiation in Bacillus subtilis cell division. Nat Commun 2021; 12:2448. [PMID: 33907196 PMCID: PMC8079713 DOI: 10.1038/s41467-021-22526-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 03/16/2021] [Indexed: 12/16/2022] Open
Abstract
Despite the central role of division in bacterial physiology, how division proteins work together as a nanoscale machine to divide the cell remains poorly understood. Cell division by cell wall synthesis proteins is guided by the cytoskeleton protein FtsZ, which assembles at mid-cell as a dense Z-ring formed of treadmilling filaments. However, although FtsZ treadmilling is essential for cell division, the function of FtsZ treadmilling remains unclear. Here, we systematically resolve the function of FtsZ treadmilling across each stage of division in the Gram-positive model organism Bacillus subtilis using a combination of nanofabrication, advanced microscopy, and microfluidics to measure the division-protein dynamics in live cells with ultrahigh sensitivity. We find that FtsZ treadmilling has two essential functions: mediating condensation of diffuse FtsZ filaments into a dense Z-ring, and initiating constriction by guiding septal cell wall synthesis. After constriction initiation, FtsZ treadmilling has a dispensable function in accelerating septal constriction rate. Our results show that FtsZ treadmilling is critical for assembling and initiating the bacterial cell division machine. Bacterial cell division by cell wall synthesis proteins is guided by treadmilling filaments of the cytoskeleton protein FtsZ. Here authors use nanofabrication, advanced microscopy, and microfluidics to resolve the function of FtsZ treadmilling in the Gram-positive model organism Bacillus subtilis.
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11
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Croop B, Tang J, Han KY. Single-shot, shadowless total internal reflection fluorescence microscopy via annular fiber bundle. OPTICS LETTERS 2020; 45:6470-6473. [PMID: 33258839 PMCID: PMC8323474 DOI: 10.1364/ol.411296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
We demonstrate a method of generating instantaneous and uniform total internal reflection fluorescence (TIRF) excitation by using an annular fiber bundle and spatially incoherent light sources. We show the flexibility of our method in that it can generate TIRF excitation with either a laser light source or an LED of different wavelengths, and facilitate switching between TIRF and epi illumination. In this report we detail the design of the fiber bundle, then demonstrate the performance via single-molecule imaging in the presence of high background and high throughput, and uniform TIRF imaging of cells over a large field of view. Our versatile method will enable quantitative shadowless TIRF imaging.
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Affiliation(s)
- Benjamin Croop
- CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32816 USA
| | - Jialei Tang
- CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32816 USA
| | - Kyu Young Han
- CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32816 USA
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12
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Garcia PD, Leach RW, Wadsworth GM, Choudhary K, Li H, Aviran S, Kim HD, Zakian VA. Stability and nuclear localization of yeast telomerase depend on protein components of RNase P/MRP. Nat Commun 2020; 11:2173. [PMID: 32358529 PMCID: PMC7195438 DOI: 10.1038/s41467-020-15875-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 03/27/2020] [Indexed: 01/17/2023] Open
Abstract
RNase P and MRP are highly conserved, multi-protein/RNA complexes with essential roles in processing ribosomal and tRNAs. Three proteins found in both complexes, Pop1, Pop6, and Pop7 are also telomerase-associated. Here, we determine how temperature sensitive POP1 and POP6 alleles affect yeast telomerase. At permissive temperatures, mutant Pop1/6 have little or no effect on cell growth, global protein levels, the abundance of Est1 and Est2 (telomerase proteins), and the processing of TLC1 (telomerase RNA). However, in pop mutants, TLC1 is more abundant, telomeres are short, and TLC1 accumulates in the cytoplasm. Although Est1/2 binding to TLC1 occurs at normal levels, Est1 (and hence Est3) binding is highly unstable. We propose that Pop-mediated stabilization of Est1 binding to TLC1 is a pre-requisite for formation and nuclear localization of the telomerase holoenzyme. Furthermore, Pop proteins affect TLC1 and the RNA subunits of RNase P/MRP in very different ways.
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Affiliation(s)
- P Daniela Garcia
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Robert W Leach
- Bioinformatics Group, Genomics Core Facility, Carl Icahn Laboratory, Princeton University, Princeton, New Jersey, 08544, USA
| | - Gable M Wadsworth
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA
| | - Krishna Choudhary
- Department of Biomedical Engineering and Genome Center, University of California, Davis, California, 95616, USA
- Gladstone Institute of Data Science and Biotechnology, San Francisco, CA, 94158, USA
| | - Hua Li
- Department of Biomedical Engineering and Genome Center, University of California, Davis, California, 95616, USA
| | - Sharon Aviran
- Department of Biomedical Engineering and Genome Center, University of California, Davis, California, 95616, USA
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA
| | - Virginia A Zakian
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA.
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13
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Gortari AN, Bouchoule S, Cambril E, Cattoni A, Hauke L, Enderlein J, Rehfeldt F, Yacomotti A. Metasurface-based total internal reflection microscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:1967-1976. [PMID: 32341860 PMCID: PMC7173909 DOI: 10.1364/boe.385276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/21/2020] [Accepted: 03/06/2020] [Indexed: 06/01/2023]
Abstract
Recent years have seen a tremendous progress in the development of dielectric metasurfaces for visible light applications. Such metasurfaces are ultra-thin optical devices that can manipulate optical wavefronts in an arbitrary manner. Here, we present a newly developed metasurface which allows for coupling light into a microscopy coverslip to achieve total internal reflection (TIR) excitation. TIR fluorescence microscopy (TIRFM) is an important bioimaging technique used specifically to image cellular membranes or surface-localized molecules with high contrast and low background. Its most commonly used modality is objective-type TIRFM where one couples a focused excitation laser beam at the edge of the back focal aperture of an oil-immersion objective with high numerical aperture (N.A.) to realize a high incident-angle plane wave excitation above the critical TIR angle in sample space. However, this requires bulky and expensive objectives with a limited field-of-view (FOV). The metasurface which we describe here represents a low cost and easy-to-use alternative for TIRFM. It consists of periodic 2D arrays of asymmetric structures fabricated in TiO2 on borosilicate glass. It couples up to 70% of the incident non-reflected light into the first diffraction order at an angle of 65° in glass, which is above the critical TIR angle for a glass-water interface. Only ∼7% of the light leaks into propagating modes traversing the glass surface, thus minimizing any spurious background fluorescence originating far outside the glass substrate. We describe in detail design and fabrication of the metasurface, and validate is applicability for TIRFM by imaging immunostained human mesenchymal stem cells over a FOV of 200 µm x 200 µm. We envision that these kinds of metasurfaces can become a valuable tool for low-cost and TIRFM, offering high contrast, low photodamage, and high surface selectivity in fluorescence excitation and detection.
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Affiliation(s)
- Antu Nehuen Gortari
- Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France
| | - Sophie Bouchoule
- Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France
| | - Edmond Cambril
- Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France
| | - Andrea Cattoni
- Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France
| | - Lara Hauke
- Third Institute of Physics-Biophysics, Georg August University, Göttingen, Germany
| | - Jörg Enderlein
- Third Institute of Physics-Biophysics, Georg August University, Göttingen, Germany
| | - Florian Rehfeldt
- Third Institute of Physics-Biophysics, Georg August University, Göttingen, Germany
| | - Alejandro Yacomotti
- Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France
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14
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Schaefer M, Kalwa H. Theoretical background of light-emitting diode total internal reflection fluorescence microscopy and photobleaching lifetime analysis of membrane-associated proteins-Part II. JOURNAL OF BIOPHOTONICS 2020; 13:e201960181. [PMID: 31965728 DOI: 10.1002/jbio.201960181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/16/2019] [Accepted: 01/07/2020] [Indexed: 06/10/2023]
Abstract
The selective microscopic imaging of the plasma membrane and adjacent structures by total internal reflection fluorescence (TIRF) microscopy is a versatile and frequently used technique in cell biology. A reduction of imaging artifacts in objective-type TIRF microscopy can be achieved by circular or multi-spot laser illumination or by using noncoherent light sources that are projected into the back focal plane as a light annulus. Light-emitting diode (LED)-based TIRF excitation is a recent advancement of the latter strategy. While some basic principles of LED-TIRF remain the same as in laser-based methods, the calculation of penetration depth, the flatness of illumination and the amount of available illumination power differ. This study provides the theoretical framework for the construction and adjustment of LED-TIRF. Using state-of-the art high power LED emitters, LED-TIRF achieves excitation efficiencies that are comparable to laser-based systems and homogenously illuminate the entire field of view, thus, allowing variation of the penetration depth or quantitative photobleaching-assisted imaging protocols. Using autofluorescent transmembrane, soluble and membrane-attached fusion proteins, we provide examples for a photobleaching-based assessment of the exchange kinetics of proteins within living human endothelial cells.
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Affiliation(s)
- Michael Schaefer
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
| | - Hermann Kalwa
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
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15
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Kogel A, Kalwa H, Urban N, Schaefer M. Artifact-free objective-type multicolor total internal reflection fluorescence microscopy with light-emitting diode light sources-Part I. JOURNAL OF BIOPHOTONICS 2019; 12:e201900033. [PMID: 31148410 DOI: 10.1002/jbio.201900033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/07/2019] [Accepted: 05/29/2019] [Indexed: 06/09/2023]
Abstract
Total internal reflection fluorescence excitation (TIRF) microscopy allows the selective observation of fluorescent molecules in immediate proximity to an interface between different refractive indices. Objective-type or prism-less TIRF excitation is typically achieved with laser light sources. We here propose a simple, yet optically advantageous light-emitting diode (LED)-based implementation of objective-type TIRF (LED-TIRF). The proposed LED-TIRF condenser is affordable and easy to set up at any epifluorescence microscope to perform multicolor TIRF and/or combined TIRF-epifluorescence imaging with even illumination of the entire field of view. Electrical control of LED light sources replaces mechanical shutters or optical modulators. LED-TIRF microscopy eliminates safety burdens that are associated with laser sources, offers favorable instrument lifetime and stability without active cooling. The non-coherent light source and the type of projection eliminate interference fringing and local scattering artifacts that are associated with conventional laser-TIRF. Unlike azimuthal spinning laser-TIRF, LED-TIRF does not require synchronization between beam rotation and the camera and can be monitored with either global or rolling shutter cameras. Typical implementations, such as live cell multicolor imaging in TIRF and epifluorescence of imaging of short-lived, localized translocation events of a Ca2+ -sensitive protein kinase C α fusion protein are demonstrated.
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Affiliation(s)
- Alexander Kogel
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
| | - Hermann Kalwa
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
| | - Nicole Urban
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
| | - Michael Schaefer
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany
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16
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Mohajeri N, Imani M, Akbarzadeh A, Sadighi A, Zarghami N. An update on advances in new developing DNA conjugation diagnostics and ultra-resolution imaging technologies: Possible applications in medical and biotechnological utilities. Biosens Bioelectron 2019; 144:111633. [DOI: 10.1016/j.bios.2019.111633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 12/15/2022]
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17
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Ellefsen KL, Holt JR, Chang AC, Nourse JL, Arulmoli J, Mekhdjian AH, Abuwarda H, Tombola F, Flanagan LA, Dunn AR, Parker I, Pathak MM. Myosin-II mediated traction forces evoke localized Piezo1-dependent Ca 2+ flickers. Commun Biol 2019; 2:298. [PMID: 31396578 PMCID: PMC6685976 DOI: 10.1038/s42003-019-0514-3] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 06/18/2019] [Indexed: 02/05/2023] Open
Abstract
Piezo channels transduce mechanical stimuli into electrical and chemical signals to powerfully influence development, tissue homeostasis, and regeneration. Studies on Piezo1 have largely focused on transduction of "outside-in" mechanical forces, and its response to internal, cell-generated forces remains poorly understood. Here, using measurements of endogenous Piezo1 activity and traction forces in native cellular conditions, we show that cellular traction forces generate spatially-restricted Piezo1-mediated Ca2+ flickers in the absence of externally-applied mechanical forces. Although Piezo1 channels diffuse readily in the plasma membrane and are widely distributed across the cell, their flicker activity is enriched near force-producing adhesions. The mechanical force that activates Piezo1 arises from Myosin II phosphorylation by Myosin Light Chain Kinase. We propose that Piezo1 Ca2+ flickers allow spatial segregation of mechanotransduction events, and that mobility allows Piezo1 channels to explore a large number of mechanical microdomains and thus respond to a greater diversity of mechanical cues.
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Affiliation(s)
- Kyle L. Ellefsen
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA 92697 USA
| | - Jesse R. Holt
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Center for Complex Biological Systems, UC Irvine, Irvine, CA 92697 USA
| | - Alice C. Chang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Jamison L. Nourse
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
| | - Janahan Arulmoli
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
| | - Armen H. Mekhdjian
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Hamid Abuwarda
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
| | - Francesco Tombola
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
| | - Lisa A. Flanagan
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
- Department of Neurology, UC Irvine, Irvine, CA 92697 USA
| | - Alexander R. Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
- Stanford Cardiovascular Institute, Stanford School of Medicine, Stanford, CA 94305 USA
| | - Ian Parker
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA 92697 USA
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
| | - Medha M. Pathak
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Center for Complex Biological Systems, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
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18
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Liu B, Hobson CM, Pimenta FM, Nelsen E, Hsiao J, O'Brien T, Falvo MR, Hahn KM, Superfine R. VIEW-MOD: a versatile illumination engine with a modular optical design for fluorescence microscopy. OPTICS EXPRESS 2019; 27:19950-19972. [PMID: 31503749 DOI: 10.1364/oe.27.019950] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/19/2019] [Indexed: 05/18/2023]
Abstract
We developed VIEW-MOD (Versatile Illumination Engine with a Modular Optical Design): a compact, multi-modality microscope, which accommodates multiple illumination schemes including variable angle total internal reflection, point scanning and vertical/horizontal light sheet. This system allows combining and flexibly switching between different illuminations and imaging modes by employing three electrically tunable lenses and two fast-steering mirrors. This versatile optics design provides control of 6 degrees of freedom of the illumination source (3 translation, 2 tilt, and beam shape) plus the axial position of the imaging plane. We also developed standalone software with an easy-to-use GUI to calibrate and control the microscope. We demonstrate the applications of this system and software in biosensor imaging, optogenetics and fast 3D volume imaging. This system is ready to fit into complex imaging circumstances requiring precise control of illumination and detection paths, and has a broad scope of usability for a myriad of biological applications.
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19
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Machado R, Bendesky J, Brown M, Spendier K, Hagen GM. Imaging Membrane Curvature inside a FcεRI-Centric Synapse in RBL-2H3 Cells Using TIRF Microscopy with Polarized Excitation. J Imaging 2019; 5:63. [PMID: 31360699 PMCID: PMC6663088 DOI: 10.3390/jimaging5070063] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/28/2019] [Indexed: 01/06/2023] Open
Abstract
Total internal reflection fluorescence microscopy with polarized excitation (P-TIRF) can be used to image nanoscale curvature phenomena in live cells. We used P-TIRF to visualize rat basophilic leukemia cells (RBL-2H3 cells) primed with fluorescent anti-dinitrophenyl (anti-DNP) immunoglobulin E (IgE) coming into contact with a supported lipid bilayer containing mobile, monovalent DNP, modeling an immunological synapse. The spatial relationship of the IgE-bound high affinity IgE receptor (FcεRI) to the ratio image of P-polarized excitation and S-polarized excitation was analyzed. These studies help correlate the dynamics of cell surface molecules with the mechanical properties of the plasma membrane during synapse formation.
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Affiliation(s)
- Rosa Machado
- UCCS Center for the Biofrontiers Institute, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
| | - Justin Bendesky
- UCCS Center for the Biofrontiers Institute, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
| | - Madison Brown
- UCCS Center for the Biofrontiers Institute, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
- Department of Physics and Energy Science, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
| | - Kathrin Spendier
- UCCS Center for the Biofrontiers Institute, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
- Department of Physics and Energy Science, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
| | - Guy M. Hagen
- UCCS Center for the Biofrontiers Institute, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA
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20
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Liu J, Kong C, Li Q, Zhao W, Li M, Gao S, Liu C, Tan J. Artifact-free, penetration-adjustable elliptical-mirror-based TIRF microscopy. OPTICS EXPRESS 2018; 26:26065-26079. [PMID: 30469699 DOI: 10.1364/oe.26.026065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/13/2018] [Indexed: 06/09/2023]
Abstract
Evanescent field distribution in the focal region of the elliptical-mirror-based total-internal-reflection fluorescence (e-TIRF) microscopy is analyzed based on vectorial diffraction theory. The simulation demonstrates that the intensity of an evanescent field generated by elliptical mirror decreases exponentially with the penetration depth, and the polarization characteristic of the evanescent wave in various directions is given. We build up an e-TIRF microscope utilizing a focused hollow-cone illumination with all-direction and large range of incidence. The experiment shows the artifact effect can be well suppressed by using the azimuthal-direction illumination method. In addition, the penetration depth of the evanescent field can be controlled by adjusting the sizes of the aperture and obstruction with a large range.
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21
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Schmidt A, Altincekic N, Gustmann H, Wachtveitl J, Hengesbach M. The Protein Microenvironment Governs the Suitability of Labeling Sites for Single-Molecule Spectroscopy of RNP Complexes. ACS Chem Biol 2018; 13:2472-2483. [PMID: 30060648 DOI: 10.1021/acschembio.8b00348] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Single-molecule techniques allow unique insights into biological systems as they provide unrivaled access to structural dynamics and conformational heterogeneity. One major bottleneck for reliable single-molecule Förster resonance energy transfer (smFRET) analysis is the identification of suitable fluorophore labeling sites that neither impair the function of the biological system nor cause photophysical artifacts of the fluorophore. To address this issue, we identified the contribution of virtually all individual parameters that affect Förster resonance energy transfer between two fluorophores attached to a ribonucleoprotein complex consisting of the RNA-binding protein L7Ae and a cognate kink turn containing RNA. A non-natural amino acid was incorporated at various positions of the protein using an amber suppression system (pEVOL) to label the protein via copper(I)-catalyzed alkyne-azide cycloaddition. On the basis of simulations followed by functional, structural, and multiparameter fluorescence analysis of five different smFRET RNPs, new insights into the design of smFRET RNPs were obtained. From this, a correlation between the photophysical properties of fluorophores attached to the protein and the predictability of the corresponding smFRET construct was established. Additionally, we identify a straightforward experimental method for characterizing selected labeling sites. Overall, this protocol allows fast generation and assessment of functional RNPs for accurate single-molecule experiments.
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Affiliation(s)
- Andreas Schmidt
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt, 60438 Frankfurt, Germany
| | - Nadide Altincekic
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt, 60438 Frankfurt, Germany
| | - Henrik Gustmann
- Institute for Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438 Frankfurt, Germany
| | - Josef Wachtveitl
- Institute for Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438 Frankfurt, Germany
| | - Martin Hengesbach
- Institute for Organic Chemistry and Chemical Biology, Goethe-University Frankfurt, 60438 Frankfurt, Germany
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22
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Schreiber B, Heil HS, Kamp M, Heinze KG. Live-cell fluorescence imaging with extreme background suppression by plasmonic nanocoatings. OPTICS EXPRESS 2018; 26:21301-21313. [PMID: 30119432 DOI: 10.1364/oe.26.021301] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/05/2018] [Indexed: 06/08/2023]
Abstract
Fluorescence microscopy allows specific and selective imaging of biological samples. Unfortunately, unspecific background due to auto-fluorescence, scattering, and non-ideal labeling efficiency often adversely affect imaging. Surface plasmon-coupled emission (SPCE) is known to selectively mediate fluorescence that spatially originates from regions close to the metal interface. However, SPCE combined with fluorescence imaging has not been widely successful so far, most likely due to its limited photon yield, which makes it tedious to identify the exact window of the application. As the strength of SPCE based imaging is its unique sectioning capabilities. We decided to identify its clear beneficial operational regime for biological settings by interrogating samples in the presence of ascending background levels. For fluorescent beads as well as live-cell imaging as examples, we show how to extend the imaging performance in extremely high photon background environments. In a common setup using plasmonic gold-coated coverslips using an objective-based total internal reflection fluorescence microscope (TIRF-M), we theoretically and experimentally characterize our fluoplasmonics (f-Pics) approach by providing general user guidance in choosing f-Pics over TIRF-M or classical wide-field (WF).
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23
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Deußner-Helfmann NS, Auer A, Strauss MT, Malkusch S, Dietz MS, Barth HD, Jungmann R, Heilemann M. Correlative Single-Molecule FRET and DNA-PAINT Imaging. NANO LETTERS 2018; 18:4626-4630. [PMID: 29943993 DOI: 10.1021/acs.nanolett.8b02185] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
DNA-PAINT is an optical super-resolution microscopy method that can visualize nanoscale protein arrangements and provide spectrally unlimited multiplexing capabilities. However, current multiplexing implementations based on, for example, DNA exchange (such as Exchange-PAINT) achieves multitarget detection by sequential imaging, limiting throughput. Here, we combine DNA-PAINT with single-molecule FRET and use the FRET efficiency as parameter for multiplexed imaging with high specificity. We demonstrate correlated single-molecule FRET and super-resolution on DNA origami structures, which are equipped with binding sequences that are targeted by pairs of dye-labeled oligonucleotides generating the FRET signal. We futher extract FRET values from single binding sites that are spaced just ∼55 nm apart, demonstrating super-resolution FRET imaging. This combination of FRET and DNA-PAINT allows for multiplexed super-resolution imaging with low background and opens the door for accurate distance readout in the 1-10 nm range.
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Affiliation(s)
- Nina S Deußner-Helfmann
- Single Molecule Biophysics, Institute of Physical and Theoretical Chemistry , Goethe-University Frankfurt , Max-von-Laue-Strasse 7 , 60438 Frankfurt , Germany
| | - Alexander Auer
- Department of Physics and Center for Nanoscience , Ludwig Maximilian University , 80539 Munich , Germany
- Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Maximilian T Strauss
- Department of Physics and Center for Nanoscience , Ludwig Maximilian University , 80539 Munich , Germany
- Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Sebastian Malkusch
- Single Molecule Biophysics, Institute of Physical and Theoretical Chemistry , Goethe-University Frankfurt , Max-von-Laue-Strasse 7 , 60438 Frankfurt , Germany
| | - Marina S Dietz
- Single Molecule Biophysics, Institute of Physical and Theoretical Chemistry , Goethe-University Frankfurt , Max-von-Laue-Strasse 7 , 60438 Frankfurt , Germany
| | - Hans-Dieter Barth
- Single Molecule Biophysics, Institute of Physical and Theoretical Chemistry , Goethe-University Frankfurt , Max-von-Laue-Strasse 7 , 60438 Frankfurt , Germany
| | - Ralf Jungmann
- Department of Physics and Center for Nanoscience , Ludwig Maximilian University , 80539 Munich , Germany
- Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Mike Heilemann
- Single Molecule Biophysics, Institute of Physical and Theoretical Chemistry , Goethe-University Frankfurt , Max-von-Laue-Strasse 7 , 60438 Frankfurt , Germany
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24
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Dynamic Ca 2+ imaging with a simplified lattice light-sheet microscope: A sideways view of subcellular Ca 2+ puffs. Cell Calcium 2017; 71:34-44. [PMID: 29604962 DOI: 10.1016/j.ceca.2017.11.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 11/29/2017] [Accepted: 11/30/2017] [Indexed: 11/24/2022]
Abstract
We describe the construction of a simplified, inexpensive lattice light-sheet microscope, and illustrate its use for imaging subcellular Ca2+ puffs evoked by photoreleased i-IP3 in cultured SH-SY5Y neuroblastoma cells loaded with the Ca2+ probe Cal520. The microscope provides sub-micron spatial resolution and enables recording of local Ca2+ transients in single-slice mode with a signal-to-noise ratio and temporal resolution (2ms) at least as good as confocal or total internal reflection microscopy. Signals arising from openings of individual IP3R channels are clearly resolved, as are stepwise changes in fluorescence reflecting openings and closings of individual channels during puffs. Moreover, by stepping the specimen through the light-sheet, the entire volume of a cell can be scanned within a few hundred ms. The ability to directly visualize a sideways (axial) section through cells directly reveals that IP3-evoked Ca2+ puffs originate at sites in very close (≤a few hundred nm) to the plasma membrane, suggesting they play a specific role in signaling to the membrane.
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25
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Schreiber B, Elsayad K, Heinze KG. Axicon-based Bessel beams for flat-field illumination in total internal reflection fluorescence microscopy. OPTICS LETTERS 2017; 42:3880-3883. [PMID: 28957150 DOI: 10.1364/ol.42.003880] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Total internal reflection fluorescence microscopy (TIRF-M) provides low-invasive high-contrast surface imaging with optical sectioning of typically 100-200 nm. Thus, TIRF-M has become an established tool for imaging surfaces, including cell membranes. For TIRF-M, a homogenous evanescent field of excitation over the whole field of view is generally desired for quantitative microscopy; however, this is not necessarily straightforward to generate with Gaussian beams. In recent years, several improvements on TIRF-M have been developed that have addressed non-uniform scattering fringes and other artifacts. Here, we introduce a cost-effective TIRF setup with a very low degree of complexity and no moving parts, which provides a flattop-like excitation profile. The setup uses a tunable laser ring zoom focus system to generate a full 360° TIRF illumination. Two axicon lenses and one focus lens allow for generation and control of the ring diameter to tune the TIRF excitation angle. We show that 360° laser illumination in combination with a radial polarizer will generate an evanescent Bessel-beam excitation field that exhibits a flattop intensity over an extended part of the field of view, and demonstrate the advantages of this axicon-based Bessel beam illumination for live-cell imaging.
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26
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Oreopoulos J, Gray-Owen SD, Yip CM. High Density or Urban Sprawl: What Works Best in Biology? ACS NANO 2017; 11:1131-1135. [PMID: 28112892 DOI: 10.1021/acsnano.7b00061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
With new approaches in imaging-from new tools or reagents to processing algorithms-come unique opportunities and challenges to our understanding of biological processes, structures, and dynamics. Although innovations in super-resolution imaging are affording novel perspectives into how molecules structurally associate and localize in response to, or in order to initiate, specific signaling events in the cell, questions arise as to how to interpret these observations in the context of biological function. Just as each neighborhood in a city has its own unique vibe, culture, and indeed density, recent work has shown that membrane receptor behavior and action is governed by their localization and association state. There is tremendous potential in developing strategies for tracking how the populations of these molecular neighborhoods change dynamically.
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Affiliation(s)
- John Oreopoulos
- Institute of Biomaterials and Biomedical Engineering, University of Toronto , Toronto M5S 3G9, Canada
| | - Scott D Gray-Owen
- Department of Molecular Genetics, University of Toronto , Toronto M5S 1A8, Canada
| | - Christopher M Yip
- Institute of Biomaterials and Biomedical Engineering, University of Toronto , Toronto M5S 3G9, Canada
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27
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Courtheoux T, Enchev RI, Lampert F, Gerez J, Beck J, Picotti P, Sumara I, Peter M. Cortical dynamics during cell motility are regulated by CRL3(KLHL21) E3 ubiquitin ligase. Nat Commun 2016; 7:12810. [PMID: 27641145 PMCID: PMC5031805 DOI: 10.1038/ncomms12810] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 08/01/2016] [Indexed: 12/18/2022] Open
Abstract
Directed cell movement involves spatial and temporal regulation of the cortical microtubule (Mt) and actin networks to allow focal adhesions (FAs) to assemble at the cell front and disassemble at the rear. Mts are known to associate with FAs, but the mechanisms coordinating their dynamic interactions remain unknown. Here we show that the CRL3KLHL21 E3 ubiquitin ligase promotes cell migration by controlling Mt and FA dynamics at the cell cortex. Indeed, KLHL21 localizes to FA structures preferentially at the leading edge, and in complex with Cul3, ubiquitylates EB1 within its microtubule-interacting CH-domain. Cells lacking CRL3KLHL21 activity or expressing a non-ubiquitylatable EB1 mutant protein are unable to migrate and exhibit strong defects in FA dynamics, lamellipodia formation and cortical plasticity. Our study thus reveals an important mechanism to regulate cortical dynamics during cell migration that involves ubiquitylation of EB1 at focal adhesions. Although focal adhesions (FAs) and microtubules (MTs) are known to associate, the underlying regulation of this dynamic interaction is not understood. Here the authors discover that the CRL3KLHL21 E3 ubiquitin ligase localises to FAs and ubiquitinates the MT plus-tip binding protein EB1, thereby promoting MT and FA dynamics and cell migration.
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Affiliation(s)
- Thibault Courtheoux
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Radoslav I Enchev
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Fabienne Lampert
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Juan Gerez
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Jochen Beck
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Paola Picotti
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Izabela Sumara
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Centre National de la Recherche Scientifique UMR 7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, 67404 Illkirch, France
| | - Matthias Peter
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
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Ki J, Arumugam P, Song JM. TIRF high-content assay development for the evaluation of drug efficacy of chemotherapeutic agents against EGFR-/HER2-positive breast cancer cell lines. Anal Bioanal Chem 2016; 408:3233-8. [PMID: 26886741 DOI: 10.1007/s00216-016-9387-1] [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: 11/24/2015] [Accepted: 02/02/2016] [Indexed: 01/06/2023]
Abstract
Elevated expression of epidermal growth factor receptor (EGFR) is reported to be associated with poor prognosis in breast cancer. EGFR subtype identification plays a crucial role in deciding the drug combination to treat the cancer patients. Conventional application of immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) produces more discordance results in EGFR subtype identification of cancer specimens. The present study is designed to develop an analytical method for simultaneous identification of cell surface biomarkers and quantitative estimation of drug efficacy in cancer specimens. For this study, we have utilized a total internal reflection fluorescence microscope (TIRFM), Qdot molecular probes and chemotherapeutic agent camptothecin (CPT)-treated breast cancer cell lines namely MCF-7, SK-BR-3 and JIMT-1. Highly sensitive detection signals with low background noise generated from the evanescent field excitation of TIRFM make it a highly suitable tool to detect the cell surface biomarkers in living cells. Moreover, single wavelength excitation of Qdot probes offers multicolour imaging with strong emission brightness. In the present study, TIRF high-content imaging system simultaneously showed the expression pattern of EGFRs and EC50 value for CPT-induced apoptosis and necrosis in MCF-7, SK-BR-3 and JIMT-1 cancer cell lines.
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Affiliation(s)
- Jieun Ki
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-ku, Seoul, 151-742, Republic of Korea
| | - Parthasarathy Arumugam
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-ku, Seoul, 151-742, Republic of Korea
| | - Joon Myong Song
- College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-ku, Seoul, 151-742, Republic of Korea.
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Genetically targeted single-channel optical recording reveals multiple Orai1 gating states and oscillations in calcium influx. Proc Natl Acad Sci U S A 2015; 113:440-5. [PMID: 26712003 DOI: 10.1073/pnas.1523410113] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Orai1 comprises the pore-forming subunit of the Ca(2+) release-activated Ca(2+) (CRAC) channel. When bound and activated by stromal interacting molecule 1 (STIM1), an endoplasmic reticulum (ER)-resident calcium sensor, Orai1 channels possess high selectivity for calcium but extremely small conductance that has precluded direct recording of single-channel currents. We have developed an approach to visualize Orai1 activity by fusing Orai1 to fluorescent, genetically encoded calcium indicators (GECIs). The GECI-Orai1 probes reveal local Ca(2+) influx at STIM1-Orai1 puncta. By whole cell recording, these fusions are fully functional as CRAC channels. When GECI-Orai1 and the CRAC-activating domain (CAD) of STIM1 were coexpressed at low levels and imaged using a total internal reflectance fluorescence microscope, cells exhibited sporadic fluorescence transients the size of diffraction-limited spots and the brightness of a few activated GECI proteins. Transients typically rose rapidly and fell into two classes according to duration: briefer "flickers" lasting only a few hundred milliseconds, and longer "pulses" lasting one to several seconds. The size, intensity, trace shape, frequency, distribution, physiological characteristics, and association with CAD binding together demonstrate that GECI-Orai1 fluorescence transients correspond to single-channel Orai1 responses. Single Orai1 channels gated by CAD, and small Orai1 puncta gated by STIM1, exhibit repetitive fluctuations in single-channel output. CAD binding supports a role in open state maintenance and reveals a second phase of CAD/STIM1 binding after channel opening. These first recordings of single-channel Orai1 currents reveal unexpected dynamics, and when paired with CAD association, support multiple single-channel states.
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