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Gardeazabal Rodriguez PF, Lilach Y, Ambegaonkar A, Vitali T, Jafri H, Sohn HW, Dalva M, Pierce S, Chung I. MAxSIM: multi-angle-crossing structured illumination microscopy with height-controlled mirror for 3D topological mapping of live cells. Commun Biol 2023; 6:1034. [PMID: 37828050 PMCID: PMC10570291 DOI: 10.1038/s42003-023-05380-2] [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: 01/04/2023] [Accepted: 09/21/2023] [Indexed: 10/14/2023] Open
Abstract
Mapping 3D plasma membrane topology in live cells can bring unprecedented insights into cell biology. Widefield-based super-resolution methods such as 3D-structured illumination microscopy (3D-SIM) can achieve twice the axial ( ~ 300 nm) and lateral ( ~ 100 nm) resolution of widefield microscopy in real time in live cells. However, twice-resolution enhancement cannot sufficiently visualize nanoscale fine structures of the plasma membrane. Axial interferometry methods including fluorescence light interference contrast microscopy and its derivatives (e.g., scanning angle interference microscopy) can determine nanoscale axial locations of proteins on and near the plasma membrane. Thus, by combining super-resolution lateral imaging of 2D-SIM with axial interferometry, we developed multi-angle-crossing structured illumination microscopy (MAxSIM) to generate multiple incident angles by fast, optoelectronic creation of diffraction patterns. Axial localization accuracy can be enhanced by placing cells on a bottom glass substrate, locating a custom height-controlled mirror (HCM) at a fixed axial position above the glass substrate, and optimizing the height reconstruction algorithm for noisy experimental data. The HCM also enables imaging of both the apical and basal surfaces of a cell. MAxSIM with HCM offers high-fidelity nanoscale 3D topological mapping of cell plasma membranes with near-real-time ( ~ 0.5 Hz) imaging of live cells and 3D single-molecule tracking.
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Affiliation(s)
| | - Yigal Lilach
- Nanofabrication and Imaging Center, George Washington University, Washington, DC, USA
| | - Abhijit Ambegaonkar
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, MD, USA
| | - Teresa Vitali
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
| | - Haani Jafri
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Hae Won Sohn
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, MD, USA
| | - Matthew Dalva
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA
| | - Susan Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, MD, USA
| | - Inhee Chung
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA.
- Department of Biomedical Engineering, GW School of Engineering and Applied Science, George Washington University, Washington, DC, USA.
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2
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Townsend JA, Marty MT. What's the defect? Using mass defects to study oligomerization of membrane proteins and peptides in nanodiscs with native mass spectrometry. Methods 2023; 218:1-13. [PMID: 37482149 PMCID: PMC10529358 DOI: 10.1016/j.ymeth.2023.07.004] [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: 04/21/2023] [Revised: 06/20/2023] [Accepted: 07/03/2023] [Indexed: 07/25/2023] Open
Abstract
Many membrane proteins form functional complexes that are either homo- or hetero-oligomeric. However, it is challenging to characterize membrane protein oligomerization in intact lipid bilayers, especially for polydisperse mixtures. Native mass spectrometry of membrane proteins and peptides inserted in lipid nanodiscs provides a unique method to study the oligomeric state distribution and lipid preferences of oligomeric assemblies. To interpret these complex spectra, we developed novel data analysis methods using macromolecular mass defect analysis. Here, we provide an overview of how mass defect analysis can be used to study oligomerization in nanodiscs, discuss potential limitations in interpretation, and explore strategies to resolve these ambiguities. Finally, we review recent work applying this technique to studying formation of antimicrobial peptide, amyloid protein, and viroporin complexes with lipid membranes.
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Affiliation(s)
- Julia A Townsend
- Department of Chemistry and Biochemistry and Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T Marty
- Department of Chemistry and Biochemistry and Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA.
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3
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Belyy V, Zuazo-Gaztelu I, Alamban A, Ashkenazi A, Walter P. Endoplasmic reticulum stress activates human IRE1α through reversible assembly of inactive dimers into small oligomers. eLife 2022; 11:e74342. [PMID: 35730415 PMCID: PMC9217129 DOI: 10.7554/elife.74342] [Citation(s) in RCA: 9] [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: 10/08/2021] [Accepted: 04/19/2022] [Indexed: 01/24/2023] Open
Abstract
Protein folding homeostasis in the endoplasmic reticulum (ER) is regulated by a signaling network, termed the unfolded protein response (UPR). Inositol-requiring enzyme 1 (IRE1) is an ER membrane-resident kinase/RNase that mediates signal transmission in the most evolutionarily conserved branch of the UPR. Dimerization and/or higher-order oligomerization of IRE1 are thought to be important for its activation mechanism, yet the actual oligomeric states of inactive, active, and attenuated mammalian IRE1 complexes remain unknown. We developed an automated two-color single-molecule tracking approach to dissect the oligomerization of tagged endogenous human IRE1 in live cells. In contrast to previous models, our data indicate that IRE1 exists as a constitutive homodimer at baseline and assembles into small oligomers upon ER stress. We demonstrate that the formation of inactive dimers and stress-dependent oligomers is fully governed by IRE1's lumenal domain. Phosphorylation of IRE1's kinase domain occurs more slowly than oligomerization and is retained after oligomers disassemble back into dimers. Our findings suggest that assembly of IRE1 dimers into larger oligomers specifically enables trans-autophosphorylation, which in turn drives IRE1's RNase activity.
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Affiliation(s)
- Vladislav Belyy
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | | | - Andrew Alamban
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Avi Ashkenazi
- Cancer Immunology, Genentech, IncSouth San FranciscoUnited States
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California, San FranciscoSan FranciscoUnited States
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4
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Single-molecule fluorescence vistas of how lipids regulate membrane proteins. Biochem Soc Trans 2021; 49:1685-1694. [PMID: 34346484 DOI: 10.1042/bst20201074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 12/17/2022]
Abstract
The study of membrane proteins is undergoing a golden era, and we are gaining unprecedented knowledge on how this key group of proteins works. However, we still have only a basic understanding of how the chemical composition and the physical properties of lipid bilayers control the activity of membrane proteins. Single-molecule (SM) fluorescence methods can resolve sample heterogeneity, allowing to discriminate between the different molecular populations that biological systems often adopt. This short review highlights relevant examples of how SM fluorescence methodologies can illuminate the different ways in which lipids regulate the activity of membrane proteins. These studies are not limited to lipid molecules acting as ligands, but also consider how the physical properties of the bilayer can be determining factors on how membrane proteins function.
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5
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Kim H, Hoshi M, Iijima M, Kuroda S, Nakamura C. Development of a universal method for the measurement of binding affinities of antibody drugs towards a living cell based on AFM force spectroscopy. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:2922-2927. [PMID: 32930215 DOI: 10.1039/d0ay00788a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A universal method to measure the binding affinities of antibody drugs towards their targets on the surface of living cells was developed based on atomic force microscopy (AFM) analysis. Nivolumab, an antibody drug targeting programmed cell death 1 (PD-1), was mainly used as a model for this evaluation. The surface of a tip-less AFM cantilever was coated with nano-capsules, on which immunoglobulin G-binding ZZ domains of protein A were exposed, and nivolumab molecules were immobilized on the cantilever through binding between the antibody Fc domains and the ZZ domains, which controlled the molecular orientation of the antibodies. Model human T lymphocytes (Jurkat), on which PD-1 molecules were highly expressed, were immobilized on a glass substrate via a lipid bilayer-anchoring reagent. The nivolumab-coated AFM cantilever was moved to approach the T cells, and the rupture forces between nivolumab molecules on the AFM cantilever and PD-1 molecules on the cell surface were measured. The average values of the rupture forces were 0.18 ± 0.10, 0.21 ± 0.18, 0.12 ± 0.07, 0.11 ± 0.06, and 0.12 ± 0.06 nN μm-2 at loading forces of 10, 20, 30, 40, and 50 nN, respectively. Application of significantly higher loading forces decreased the S/N ratio, as confirmed by comparison with control T cells with low PD-1 expression, which suggested that a low loading force of less than 20 nN was sufficient for these measurements. A correlation between the expression levels of PD-1 and the rupture force values was confirmed using immunofluorescence. A similar assay was performed by using an antibody drug targeting epidermal growth factor receptor (EGFR) and a model cancer cell expressing EGFR molecules (A431) to evaluate the universal application of the developed method for various antibody drugs, and the same conclusions as that in nivolumab's case were obtained. This method can be applied to living cells without any chemical treatment, which allows the present method to compare the affinities of various antibody drugs towards the same single cell. These results indicated that the present method is useful for selecting the most effective candidates from various antibody drugs from the point of view of binding forces between antibodies and living cells.
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Affiliation(s)
- Hyonchol Kim
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan.
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo, Japan
| | - Masamichi Hoshi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan.
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo, Japan
| | - Masumi Iijima
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
- Department of Biomolecular Science and Reaction, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka 567-0047, Ibaraki, Japan
| | - Shun'ichi Kuroda
- Department of Biomolecular Science and Reaction, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka 567-0047, Ibaraki, Japan
| | - Chikashi Nakamura
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan.
- Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo, Japan
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Teng IT, Bu X, Chung I. Conjugation of Fab' Fragments with Fluorescent Dyes for Single-Molecule Tracking On Live Cells. Bio Protoc 2019; 9:e3375. [PMID: 33654871 DOI: 10.21769/bioprotoc.3375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 12/28/2022] Open
Abstract
Our understanding of the regulation and functions of cell-surface proteins has progressed rapidly with the advent of advanced optical imaging techniques. In particular, single-molecule tracking (SMT) using bright fluorophores conjugated to antibodies and wide-field microscopy methods such as total internal reflection fluorescence microscopy have become valuable tools to discern how endogenous proteins control cell biology. Yet, some technical challenges remain; in SMT, these revolve around the characteristics of the labeling reagent. A good reagent should have neutrality (in terms of not affecting the target protein's functions), tagging specificity, and a bright fluorescence signal. In addition, a long shelf-life is desirable due to the time and monetary costs associated with reagent preparation. Semiconductor-based quantum dots (Qdots) or Janelia Fluor (JF) dyes are bright and photostable, and are thus excellent candidates for SMT tagging. Neutral, high-affinity antibodies can selectively bind to target proteins. However, the bivalency of antibodies can cause simultaneous binding to two proteins, and this bridging effect can alter protein functions and behaviors. Bivalency can be avoided using monovalent Fab fragments generated by enzymatic digestion of neutral antibodies. However, conjugation of a Fab with a dye using the chemical cross-linking agent SMCC (succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate) requires reduction of the interchain disulfide bond within the Fab fragment, which can decrease the structural stability of the Fab and weaken its antigen-binding capability. To overcome this problem, we perform limited reduction of F(ab')2 to generate Fab' fragments using a weak reducer, cysteamine, which yields free sulfhydryl groups in the hinge region, while the interchain disulfide bond in Fab' is intact. Here, we describe a method that generates Fab' with high yield from two isoforms of IgG and conjugates the Fab' fragments with Qdots. This conjugation scheme can be applied easily to other types of dyes with similar chemical characteristics.
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Affiliation(s)
- I-Ting Teng
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Xiangning Bu
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Inhee Chung
- Department of Anatomy and Cell Biology, George Washington University, School of Medicine and Health Sciences, Washington, District of Columbia, USA
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Biological
membranes are tricky to investigate. They are complex
in terms of molecular composition and structure, functional
over a wide range of time scales, and characterized
by nonequilibrium conditions. Because of all of these
features, simulations are a great technique to study biomembrane
behavior. A significant part of the functional processes
in biological membranes takes place at the molecular
level; thus computer simulations are the method of
choice to explore how their properties emerge from specific
molecular features and how the interplay among the numerous
molecules gives rise to function over spatial and
time scales larger than the molecular ones. In this
review, we focus on this broad theme. We discuss the current
state-of-the-art of biomembrane simulations that, until
now, have largely focused on a rather narrow picture
of the complexity of the membranes. Given this, we
also discuss the challenges that we should unravel in the
foreseeable future. Numerous features such as the actin-cytoskeleton
network, the glycocalyx network, and nonequilibrium
transport under ATP-driven conditions have so far
received very little attention; however, the potential
of simulations to solve them would be exceptionally high. A
major milestone for this research would be that one day
we could say that computer simulations genuinely research
biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Matti Javanainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo naḿesti 542/2 , 16610 Prague , Czech Republic.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Waldemar Kulig
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Tomasz Róg
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Ilpo Vattulainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland.,MEMPHYS-Center for Biomembrane Physics
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8
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Song D, Jung Y. Homo-molecular Fluorescence Complementation for Direct Visualization of Receptor Oligomerization in Living Cells. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201812780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Daesun Song
- Department of Chemistry; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 34141 Korea
| | - Yongwon Jung
- Department of Chemistry; Korea Advanced Institute of Science and Technology (KAIST); Daejeon 34141 Korea
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9
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Song D, Jung Y. Homo-molecular Fluorescence Complementation for Direct Visualization of Receptor Oligomerization in Living Cells. Angew Chem Int Ed Engl 2019; 58:2045-2049. [PMID: 30561874 DOI: 10.1002/anie.201812780] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Indexed: 01/14/2023]
Abstract
Cell surface receptor oligomerization is an attractive target process for drug screening. However, simple but reliable (and thus high-throughput) visualization methods for receptor oligomerization are still lacking. Herein, we report on a new single-construct homo-molecular fluorescence complementation (Homo-FC) probe, which shows strong fluorescence signals by oligomerization of fused receptors in living cells with unexpectedly low background signals. Importantly, this high signal-to-noise ratio was not affected by expression level variations of fused receptors. The Homo-FC probe was developed by optimized flopped fusion of split fragments of superfolder green fluorescence protein and subsequent surface charge engineering. Homo-FC reliably visualized the oligomerization of diverse natural receptors such as GPCR, EGFR, and even cytosolic DAI.
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Affiliation(s)
- Daesun Song
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
| | - Yongwon Jung
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
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10
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Surfaceome nanoscale organization and extracellular interaction networks. Curr Opin Chem Biol 2018; 48:26-33. [PMID: 30308468 DOI: 10.1016/j.cbpa.2018.09.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/16/2018] [Accepted: 09/19/2018] [Indexed: 12/19/2022]
Abstract
The reductionist view of 'one target-one drug' has fueled the development of therapeutic agents to treat human disease. However, many compounds that have efficacy in vitro are inactive in complex in vivo systems. It has become clear that a molecular understanding of signaling networks is needed to address disease phenotypes in the human body. Protein signaling networks function at the molecular level through information transfer via protein-protein interactions. Cell surface exposed proteins, termed the surfaceome, are the gatekeepers between the intra- and extracellular signaling networks, translating extracellular cues into intracellular responses and vice versa. As 66% of drugs in the DrugBank target the surfaceome, these proteins are a key source for potential diagnostic and therapeutic agents. In this review article, we will discuss current knowledge about the spatial organization and molecular interactions of the surfaceome and provide a perspective on the technologies available for studying the extracellular surfaceome interaction network.
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