1
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Mariconti M, Dechamboux L, Heckmann M, Gros J, Morel M, Escriou V, Baigl D, Hoffmann C, Rudiuk S. Intracellular Delivery of Functional Proteins with DNA-Protein Nanogels-Lipids Complex. J Am Chem Soc 2024; 146:5118-5127. [PMID: 38363821 PMCID: PMC10910493 DOI: 10.1021/jacs.3c08000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/18/2024]
Abstract
Using functional proteins for therapeutic purposes due to their high selectivity and/or catalytic properties can enable the control of various cellular processes; however, the transport of active proteins inside living cells remains a major challenge. In contrast, intracellular delivery of nucleic acids has become a routine method for a number of applications in gene therapy, genome editing, or immunization. Here we report a functionalizable platform constituting of DNA-protein nanogel carriers cross-linked through streptavidin-biotin or streptactin-biotin interactions and demonstrate its applicability for intracellular delivery of active proteins. We show that the nanogels can be loaded with proteins bearing either biotin, streptavidin, or strep-tag, and the resulting functionalized nanogels can be delivered into living cells after complexation with cationic lipid vectors. We use this approach for delivery of alkaline phosphatase enzyme, which is shown to keep its catalytic activity after internalization by mouse melanoma B16 cells, as demonstrated by the DDAO-phosphate assay. The resulting functionalized nanogels have dimensions on the order of 100 nm, contain around 100 enzyme molecules, and are shown to be transfectable at low lipid concentrations (charge ratio R± = 0.75). This ensures the low toxicity of our system, which in combination with high local enzyme concentration (∼100 μM) underlines potential interest of this nanoplatform for biomedical applications.
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Affiliation(s)
- Marina Mariconti
- PASTEUR,
UMR8640, Department of Chemistry, PSL University,
Sorbonne Université, CNRS, Ecole Normale Supérieure, Paris 75005 France
| | | | - Marion Heckmann
- Université
Paris Cité, CNRS, INSERM, UTCBS, Paris 75006, France
| | - Julien Gros
- PASTEUR,
UMR8640, Department of Chemistry, PSL University,
Sorbonne Université, CNRS, Ecole Normale Supérieure, Paris 75005 France
| | - Mathieu Morel
- PASTEUR,
UMR8640, Department of Chemistry, PSL University,
Sorbonne Université, CNRS, Ecole Normale Supérieure, Paris 75005 France
| | | | - Damien Baigl
- PASTEUR,
UMR8640, Department of Chemistry, PSL University,
Sorbonne Université, CNRS, Ecole Normale Supérieure, Paris 75005 France
| | - Céline Hoffmann
- Université
Paris Cité, CNRS, INSERM, UTCBS, Paris 75006, France
| | - Sergii Rudiuk
- PASTEUR,
UMR8640, Department of Chemistry, PSL University,
Sorbonne Université, CNRS, Ecole Normale Supérieure, Paris 75005 France
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2
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Chan SJW, Zhu JY, Mia Soh WW, Bazan GC. Real-Time Monitoring of Mitochondrial Damage Using Conjugated Oligoelectrolytes. J Am Chem Soc 2024; 146:660-667. [PMID: 38131111 DOI: 10.1021/jacs.3c10531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Conjugated oligoelectrolytes (COEs) comprise a class of fluorescent reporters with tunable optical properties and lipid bilayer affinity. These molecules have proven effective in a range of bioimaging applications; however, their use in characterizing specific subcellular structures remains restricted. Such capabilities would broaden COE applications to understand cellular dysfunction, cell communication, and the targets of different pharmaceutical agents. Here, we disclose a novel COE derivative, COE-CN, which enables the visualization of mitochondria, including morphological changes and lysosomal fusion upon treatment with depolarizing agents. COE-CN is characterized by the presence of imidazolium solubilizing groups and an optically active cyanovinyl-linked distyrylbenzene core with intramolecular charge-transfer characteristics. Our current understanding is that the relatively shorter molecular length of COE-CN leads to weaker binding within lipid bilayer membranes, which allows sampling of internal cellular structures and ultimately to different localization relative to elongated COEs. As a means of practical demonstration, COE-CN can be used to diagnose cells with damaged mitochondria via flow cytometry. Coupled with an elongated COE that does not translocate upon depolarization, changes in ratiometric fluorescence intensity can be used to monitor mitochondrial membrane potential disruption, demonstrating the potential for use in diagnostic assays.
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Affiliation(s)
- Samuel J W Chan
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Ji-Yu Zhu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Wilson Wee Mia Soh
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Guillermo C Bazan
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117544, Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117585, Singapore
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3
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Alfonso C, Sobrinos-Sanguino M, Luque-Ortega JR, Zorrilla S, Monterroso B, Nuero OM, Rivas G. Studying Macromolecular Interactions of Cellular Machines by the Combined Use of Analytical Ultracentrifugation, Light Scattering, and Fluorescence Spectroscopy Methods. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 3234:89-107. [PMID: 38507202 DOI: 10.1007/978-3-031-52193-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Cellular machines formed by the interaction and assembly of macromolecules are essential in many processes of the living cell. These assemblies involve homo- and hetero-associations, including protein-protein, protein-DNA, protein-RNA, and protein-polysaccharide associations, most of which are reversible. This chapter describes the use of analytical ultracentrifugation, light scattering, and fluorescence-based methods, well-established biophysical techniques, to characterize interactions leading to the formation of macromolecular complexes and their modulation in response to specific or unspecific factors. We also illustrate, with several examples taken from studies on bacterial processes, the advantages of the combined use of subsets of these techniques as orthogonal analytical methods to analyze protein oligomerization and polymerization, interactions with ligands, hetero-associations involving membrane proteins, and protein-nucleic acid complexes.
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Affiliation(s)
- Carlos Alfonso
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
| | - Marta Sobrinos-Sanguino
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Juan Román Luque-Ortega
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Silvia Zorrilla
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Begoña Monterroso
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Oscar M Nuero
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Germán Rivas
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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4
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Schirripa Spagnolo C, Moscardini A, Amodeo R, Beltram F, Luin S. Quantitative determination of fluorescence labeling implemented in cell cultures. BMC Biol 2023; 21:190. [PMID: 37697318 PMCID: PMC10496409 DOI: 10.1186/s12915-023-01685-0] [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: 11/29/2022] [Accepted: 08/18/2023] [Indexed: 09/13/2023] Open
Abstract
BACKGROUND Labeling efficiency is a crucial parameter in fluorescence applications, especially when studying biomolecular interactions. Current approaches for estimating the yield of fluorescent labeling have critical drawbacks that usually lead them to be inaccurate or not quantitative. RESULTS We present a method to quantify fluorescent-labeling efficiency that addresses the critical issues marring existing approaches. The method operates in the same conditions of the target experiments by exploiting a ratiometric evaluation with two fluorophores used in sequential reactions. We show the ability of the protocol to extract reliable quantification for different fluorescent probes, reagents concentrations, and reaction timing and to optimize labeling performance. As paradigm, we consider the labeling of the membrane-receptor TrkA through 4'-phosphopantetheinyl transferase Sfp in living cells, visualizing the results by TIRF microscopy. This investigation allows us to find conditions for demanding single and multi-color single-molecule studies requiring high degrees of labeling. CONCLUSIONS The developed method allows the quantitative determination and the optimization of staining efficiency in any labeling strategy based on stable reactions.
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Affiliation(s)
| | - Aldo Moscardini
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Rosy Amodeo
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
- Present address: Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, Pieve Emanuele, 20072, Milan, Italy
| | - Fabio Beltram
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
- NEST Laboratory, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Stefano Luin
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy.
- NEST Laboratory, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127, Pisa, Italy.
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5
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Schirripa Spagnolo C, Luin S. Setting up multicolour TIRF microscopy down to the single molecule level. Biomol Concepts 2023; 14:bmc-2022-0032. [PMID: 37428621 DOI: 10.1515/bmc-2022-0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023] Open
Abstract
Investigating biological mechanisms in ever greater detail requires continuous advances in microscopy techniques and setups. Total internal reflection fluorescence (TIRF) microscopy is a well-established technique for visualizing processes on the cell membrane. TIRF allows studies down to the single molecule level, mainly in single-colour applications. Instead, multicolour setups are still limited. Here, we describe our strategies for implementing a multi-channel TIRF microscopy system capable of simultaneous two-channel excitation and detection, starting from a single-colour commercial setup. First, we report some applications at high molecule density and then focus on the challenges we faced for achieving the single molecule level simultaneously in different channels, showing that rigorous optimizations on the setup are needed to increase its sensitivity up to this point, from camera setting to background minimization. We also discuss our strategies regarding crucial points of fluorescent labelling for this type of experiment: labelling strategy, kind of probe, efficiency, and orthogonality of the reaction, all of which are aspects that can influence the achievable results. This work may provide useful guidelines for setting up advanced single-molecule multi-channel TIRF experiments to obtain insights into interaction mechanisms on the cell membrane of living cells.
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Affiliation(s)
| | - Stefano Luin
- NEST Laboratory, Scuola Normale Superiore, Piazza San Silvestro 12, I-56127, Pisa, Italy
- NEST Laboratory, Istituto Nanoscienze-Consiglio Nazionale delle ricerche (CNR), Piazza San Silvestro 12, I-56127, Pisa, Italy
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6
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Choosing the Probe for Single-Molecule Fluorescence Microscopy. Int J Mol Sci 2022; 23:ijms232314949. [PMID: 36499276 PMCID: PMC9735909 DOI: 10.3390/ijms232314949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/18/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Probe choice in single-molecule microscopy requires deeper evaluations than those adopted for less sensitive fluorescence microscopy studies. Indeed, fluorophore characteristics can alter or hide subtle phenomena observable at the single-molecule level, wasting the potential of the sophisticated instrumentation and algorithms developed for advanced single-molecule applications. There are different reasons for this, linked, e.g., to fluorophore aspecific interactions, brightness, photostability, blinking, and emission and excitation spectra. In particular, these spectra and the excitation source are interdependent, and the latter affects the autofluorescence of sample substrate, medium, and/or biological specimen. Here, we review these and other critical points for fluorophore selection in single-molecule microscopy. We also describe the possible kinds of fluorophores and the microscopy techniques based on single-molecule fluorescence. We explain the importance and impact of the various issues in fluorophore choice, and discuss how this can become more effective and decisive for increasingly demanding experiments in single- and multiple-color applications.
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7
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Guy CS, Tomás RMF, Tang Q, Gibson MI, Fullam E. Imaging of antitubercular dimeric boronic acids at the mycobacterial cell surface by click-probe capture. Chem Commun (Camb) 2022; 58:9361-9364. [PMID: 35917119 PMCID: PMC9387567 DOI: 10.1039/d2cc02407a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Dimeric boronic acids kill Mycobacterium tuberculosis (Mtb) by targeting mycobacterial specific extracellular glycans, removing the requirement for a therapeutic agent to permeate the complex cell envelope. Here we report the successful development and use of new ‘clickable’ boronic acid probes as a powerful method to enable the direct detection and visualisation of this unique class of cell-surface targeting antitubercular agents. Antitubercular ‘clickable’ diboronic acid agents are directly incorporated into the mycobacterial cell envelope through glycan-targeting.![]()
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Affiliation(s)
- Collette S Guy
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
| | - Ruben M F Tomás
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - Qiao Tang
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Matthew I Gibson
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - Elizabeth Fullam
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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8
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Smyth S, Zhang Z, Bah A, Tsangaris TE, Dawson J, Forman-Kay JD, Gradinaru CC. Multisite phosphorylation and binding alter conformational dynamics of the 4E-BP2 protein. Biophys J 2022; 121:3049-3060. [PMID: 35841142 PMCID: PMC9463650 DOI: 10.1016/j.bpj.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 05/19/2022] [Accepted: 07/11/2022] [Indexed: 11/02/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) play critical roles in regulatory protein interactions, but detailed structural/dynamic characterization of their ensembles remain challenging, both in isolation and when they form dynamic "fuzzy" complexes. Such is the case for mRNA cap-dependent translation initiation, which is regulated by the interaction of the predominantly folded eukaryotic initiation factor 4E (eIF4E) with the intrinsically disordered eIF4E binding proteins (4E-BPs) in a phosphorylation-dependent manner. Single-molecule Förster resonance energy transfer showed that the conformational changes of 4E-BP2 induced by binding to eIF4E are non-uniform along the sequence; while a central region containing both motifs that bind to eIF4E expands and becomes stiffer, the C-terminal region is less affected. Fluorescence anisotropy decay revealed a non-uniform segmental flexibility around six different labeling sites along the chain. Dynamic quenching of these fluorescent probes by intrinsic aromatic residues measured via fluorescence correlation spectroscopy report on transient intra- and inter-molecular contacts on nanosecond-to-microsecond timescales. Upon hyperphosphorylation, which induces folding of ∼40 residues in 4E-BP2, the quenching rates decreased at most labeling sites. The chain dynamics around sites in the C-terminal region far away from the two binding motifs significantly increased upon binding to eIF4E, suggesting that this region is also involved in the highly dynamic 4E-BP2:eIF4E complex. Our time-resolved fluorescence data paint a sequence-level rigidity map of three states of 4E-BP2 differing in phosphorylation or binding status and distinguish regions that form contacts with eIF4E. This study adds complementary structural and dynamics information to recent studies of 4E-BP2, and it constitutes an important step toward a mechanistic understanding of this important IDP via integrative modeling.
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Affiliation(s)
- Spencer Smyth
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Zhenfu Zhang
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Alaji Bah
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Thomas E Tsangaris
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Jennifer Dawson
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Julie D Forman-Kay
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.
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9
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Xu H, She P, Ma B, Zhao Z, Li G, Wang Y. ROS responsive nanoparticles loaded with lipid-specific AIEgen for atherosclerosis-targeted diagnosis and bifunctional therapy. Biomaterials 2022; 288:121734. [PMID: 35999079 DOI: 10.1016/j.biomaterials.2022.121734] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 08/03/2022] [Accepted: 08/06/2022] [Indexed: 11/25/2022]
Abstract
Atherosclerosis, which is triggered by endothelial damage, progressive local inflammation and excessive lipid accumulation, is one of the most common cardiovascular diseases in recent years. Drug delivery systems have shown great potential for the accurate diagnosis and effective treatment of early atherosclerosis, but are accompanied by disadvantages such as poor stability, lack of active targeting and non-specific recognition capabilities, which still need to be further developed. In our work, a multifunctional nanoparticle (LFP/PCDPD) with reactive oxygen species (ROS) responsive drug release, lipid removal, and lipid-specific AIE fluorescence imaging was constructed. Cyclodextrin structure with lipid removal function and PMEMA blocks with ROS-response-mediated hydrophobic to hydrophilic conversion were simultaneously introduced into the structure of LFP/PCDPD to load the anti-inflammatory drug prednisolone (Pred) and lipid-specific AIEgen (LFP). The active targeting function of LFP/PCDPD was conferred by the high affinity of dextran to the vascular adhesion molecule-1 (VCAM-1) and CD44 receptor on the surface of broken endothelial cells. After intravenous injection into ApoE-/- mice, LFP/PCDPD actively enriched in the microenvironment of local ROS overexpression and rich lipids in atherosclerosis. Pred and LFP were released while lipids were removed, thus enabling proactive targeting of atherosclerosis and efficient "two-pronged" treatment.
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Affiliation(s)
- Hong Xu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China
| | - Peiyi She
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China
| | - Boxuan Ma
- Department of Cardiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China; Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Hangzhou, 310016, China
| | - Zhiyu Zhao
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China
| | - Gaocan Li
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China.
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China
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10
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Bos I, Brink E, Michels L, Sprakel J. DNA dynamics in complex coacervate droplets and micelles. SOFT MATTER 2022; 18:2012-2027. [PMID: 35191449 PMCID: PMC8905490 DOI: 10.1039/d1sm01787j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Single stranded DNA (ssDNA), or another polyanion, can be mixed with polycations to form liquid-like complex coacervates. When the polycations are replaced by cationic-neutral diblock copolymers, complex coacervate core micelles (C3Ms) can be formed instead. In both complex coacervates and C3Ms, dynamics plays an important role. Yet, to date, the effect of chain length on the dynamics effect is still not fully understood. The DNA complexes provide a versatile platform to further elucidate these chain length effects because the DNA is monodisperse and its length can be easily adapted. Therefore, we study in this paper the dynamics of fluorescently labelled ssDNA in both complex coacervate droplets and micelles. The DNA dynamics in the complex coacervate droplets is probed by fluorescence recovery after photobleaching (FRAP). We observe that the DNA diffusion coefficient depends more strongly on the DNA length than predicted by the sticky Rouse model and we show that this can be partly explained by changes in complex coacervate density, but that also other factors might play a role. We measure the molecular exchange of C3Ms by making use of Förster resonance energy transfer (FRET) and complement these measurements with Langevin dynamics simulations. We conclude that chain length polydispersity is the main cause of a broad distribution of exchange rates. We hypothesise that the different exchange rates that we observe for the monodisperse DNA are mainly caused by differences in dye interactions and show that the dye can indeed have a large effect on the C3M exchange. In addition, we show that a new description of the C3M molecular exchange is required that accounts among others for the effect of the length of the oppositely charged core species. Together our findings can help to better understand the dynamics in both specific DNA systems and in complex coacervate droplets and micelles in general.
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Affiliation(s)
- Inge Bos
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Eline Brink
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Lucile Michels
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Joris Sprakel
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
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11
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Unraveling the hidden temporal range of fast β 2-adrenergic receptor mobility by time-resolved fluorescence. Commun Biol 2022; 5:176. [PMID: 35228644 PMCID: PMC8885909 DOI: 10.1038/s42003-022-03106-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 02/02/2022] [Indexed: 12/29/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are hypothesized to possess molecular mobility over a wide temporal range. Until now the temporal range has not been fully accessible due to the crucially limited temporal range of available methods. This in turn, may lead relevant dynamic constants to remain masked. Here, we expand this dynamic range by combining fluorescent techniques using a spot confocal setup. We decipher mobility constants of β2-adrenergic receptor over a wide time range (nanosecond to second). Particularly, a translational mobility (10 µm²/s), one order of magnitude faster than membrane associated lateral mobility that explains membrane protein turnover and suggests a wider picture of the GPCR availability on the plasma membrane. And a so far elusive rotational mobility (1-200 µs) which depicts a previously overlooked dynamic component that, despite all complexity, behaves largely as predicted by the Saffman-Delbrück model. The mobility of the β2-adrenergic receptor, from the nanosecond to the second range, is revealed by combining several fluorescent spectroscopy techniques. These data also show a previously hidden mobility of this GPCR.
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12
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Zhang O, Zhou W, Lu J, Wu T, Lew MD. Resolving the Three-Dimensional Rotational and Translational Dynamics of Single Molecules Using Radially and Azimuthally Polarized Fluorescence. NANO LETTERS 2022; 22:1024-1031. [PMID: 35073487 PMCID: PMC8893020 DOI: 10.1021/acs.nanolett.1c03948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report a radially and azimuthally polarized (raPol) microscope for high detection and estimation performance in single-molecule orientation-localization microscopy (SMOLM). With 5000 photons detected from Nile red (NR) transiently bound within supported lipid bilayers (SLBs), raPol SMOLM achieves 2.9 nm localization precision, 1.5° orientation precision, and 0.17 sr precision in estimating rotational wobble. Within DPPC SLBs, SMOLM imaging reveals the existence of randomly oriented binding pockets that prevent NR from freely exploring all orientations. Treating the SLBs with cholesterol-loaded methyl-β-cyclodextrin (MβCD-chol) causes NR's orientational diffusion to be dramatically reduced, but curiously NR's median lateral displacements drastically increase from 20.8 to 75.5 nm (200 ms time lag). These jump diffusion events overwhelmingly originate from cholesterol-rich nanodomains within the SLB. These detailed measurements of single-molecule rotational and translational dynamics are made possible by raPol's high measurement precision and are not detectable in standard SMLM.
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13
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Wichmann N, Lund PM, Hansen MB, Hjørringgaard CU, Larsen JB, Kristensen K, Andresen TL, Simonsen JB. Applying flow cytometry to identify the modes of action of membrane-active peptides in a label-free and high-throughput fashion. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183820. [PMID: 34813768 DOI: 10.1016/j.bbamem.2021.183820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/29/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
Membrane-active peptides (MAPs) have several potential therapeutic uses, including as antimicrobial drugs. Many traditional methods used to evaluate the membrane interactions of MAPs have limited applicability. Low-throughput methods, such as microscopy, provide detailed information but often rely on fluorophore-labeled MAPs, and high-throughput assays, such as the calcein release assay, cannot assess the mechanism behind the disruption of vesicular-based lipid membranes. Here we present a flow cytometric assay that provides detailed information about the peptide-lipid membrane interactions on single artificial lipid vesicles while being high-throughput (1000-2000 vesicles/s) and based on label-free MAPs. We synthesized and investigated six MAPs with different modes of action to evaluate the versatility of the assay. The assay is based on the flow cytometric readouts from artificial lipid vesicles, including the fluorescence from membrane-anchored and core-encapsulated fluorophores, and the vesicle concentration. From these parameters, we were able to distinguish between MAPs that induce vesicle solubilization, permeation (pores/membrane distortion), and aggregation or fusion. Our flow cytometry findings have been verified by traditional methods, including the calcein release assay, dynamic light scattering, and fluorescence microscopy on giant unilamellar vesicles. We envision that the presented flow cytometric assay can be used for various types of peptide-lipid membrane studies, e.g. to identify new antibiotics. Moreover, the assay can easily be expanded to derive additional valuable information.
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Affiliation(s)
- Nanna Wichmann
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Philip M Lund
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Morten B Hansen
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Claudia U Hjørringgaard
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Jannik B Larsen
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Kasper Kristensen
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Thomas L Andresen
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
| | - Jens B Simonsen
- Department of Health Technology, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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14
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Dharmarwardana M, Dempsey JM, Padilla-Coley S, Jarvis TS, Shi K, Atkinson KM, Smith BD. Supramolecular capture of highly polar amidosquaraine dye in water with nanomolar affinity and large turn-on fluorescence. Chem Commun (Camb) 2021; 57:13518-13521. [PMID: 34846389 PMCID: PMC8689413 DOI: 10.1039/d1cc05039g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A supramolecular dye-capture system comprising anionic amidosquaraine guest and macrocyclic tetralactam host exhibits nanomolar affinity and "turn on" visible fluorescence. Utility is demonstrated with a new fluorescent assay for liposome leakage induced by the biomedically important enzyme phospholipase A2.
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15
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Habibi N, Uddin S, Al‐Salameen F, Al‐Amad S, Kumar V, Al‐Otaibi M, Razzack NA, Shajan A, Shirshikar F. SARS-CoV-2, other respiratory viruses and bacteria in aerosols: Report from Kuwait's hospitals. INDOOR AIR 2021; 31:1815-1825. [PMID: 34121237 PMCID: PMC8447393 DOI: 10.1111/ina.12871] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 05/08/2023]
Abstract
The role of airborne particles in the spread of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is well explored. The novel coronavirus can survive in aerosol for extended periods, and its interaction with other viral communities can cause additional virulence and infectivity. This baseline study reports concentrations of SARS-CoV-2, other respiratory viruses, and pathogenic bacteria in the indoor air from three major hospitals (Sheikh Jaber, Mubarak Al-Kabeer, and Al-Amiri) in Kuwait dealing with coronavirus disease 2019 (COVID-19) patients. The indoor aerosol samples showed 12-99 copies of SARS-CoV-2 per m3 of air. Two non-SARS-coronavirus (strain HKU1 and NL63), respiratory syncytial virus (RSV), and human bocavirus, human rhinoviruses, Influenza B (FluB), and human enteroviruses were also detected in COVID-positive areas of Mubarak Al Kabeer hospital (MKH). Pathogenic bacteria such as Mycoplasma pneumonia, Streptococcus pneumonia and, Haemophilus influenza were also found in the hospital aerosols. Our results suggest that the existing interventions such as social distancing, use of masks, hand hygiene, surface sanitization, and avoidance of crowded indoor spaces are adequate to prevent the spread of SARS-CoV-2 in enclosed areas. However, increased ventilation can significantly reduce the concentration of SARS-CoV-2 in indoor aerosols. The synergistic or inhibitory effects of other respiratory pathogens in the spread, severity, and complexity of SARS-CoV-2 need further investigation.
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Affiliation(s)
- N. Habibi
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - S. Uddin
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - F. Al‐Salameen
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - S. Al‐Amad
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - V. Kumar
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - M. Al‐Otaibi
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - N. Abdul Razzack
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - A. Shajan
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
| | - F. Shirshikar
- Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafatKuwait
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16
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Han MJ, He QT, Yang M, Chen C, Yao Y, Liu X, Wang Y, Zhu ZL, Zhu KK, Qu C, Yang F, Hu C, Guo X, Zhang D, Chen C, Sun JP, Wang J. Single-molecule FRET and conformational analysis of beta-arrestin-1 through genetic code expansion and a Se-click reaction. Chem Sci 2021; 12:9114-9123. [PMID: 34276941 PMCID: PMC8261736 DOI: 10.1039/d1sc02653d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/02/2021] [Accepted: 05/27/2021] [Indexed: 11/21/2022] Open
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is a powerful tool for investigating the dynamic properties of biomacromolecules. However, the success of protein smFRET relies on the precise and efficient labeling of two or more fluorophores on the protein of interest (POI), which has remained highly challenging, particularly for large membrane protein complexes. Here, we demonstrate the site-selective incorporation of a novel unnatural amino acid (2-amino-3-(4-hydroselenophenyl) propanoic acid, SeF) through genetic expansion followed by a Se-click reaction to conjugate the Bodipy593 fluorophore on calmodulin (CaM) and β-arrestin-1 (βarr1). Using this strategy, we monitored the subtle but functionally important conformational change of βarr1 upon activation by the G-protein coupled receptor (GPCR) through smFRET for the first time. Our new method has broad applications for the site-specific labeling and smFRET measurement of membrane protein complexes, and the elucidation of their dynamic properties such as transducer protein selection.
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Affiliation(s)
- Ming-Jie Han
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences Tianjin Airport Economic Area Tianjin 300308 China
| | - Qing-Tao He
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University 44 Wenhua Xi Road Jinan 250012 Shandong China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education Haidian District Beijing 100191 China
- Institute of Biophysics, Chinese Academy of Sciences Chaoyang District Beijing 100101 China
| | - Mengyi Yang
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University Haidian District Beijing 100084 China
| | - Chao Chen
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences Tianjin Airport Economic Area Tianjin 300308 China
- University of the Chinese Academy of Sciences (UCAS) Shijingshan District Beijing 100049 China
| | - Yirong Yao
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University Haidian District Beijing 100084 China
| | - Xiaohong Liu
- Institute of Biophysics, Chinese Academy of Sciences Chaoyang District Beijing 100101 China
| | - Yuchuan Wang
- Shenzhen Institute of Transfusion Medicine, Shenzhen Blood Center Futian District Shenzhen 518052 China
| | - Zhong-Liang Zhu
- School of Life Sciences, University of Science and Technology of China Baohe District Anhui 230026 China
| | - Kong-Kai Zhu
- School of Biological Science and Technology, University of Jinan Jinan Shandong 250022 China
| | - Changxiu Qu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University 44 Wenhua Xi Road Jinan 250012 Shandong China
| | - Fan Yang
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University 44 Wenhua Xi Road Jinan 250012 Shandong China
| | - Cheng Hu
- Institute of Biophysics, Chinese Academy of Sciences Chaoyang District Beijing 100101 China
| | - Xuzhen Guo
- Institute of Biophysics, Chinese Academy of Sciences Chaoyang District Beijing 100101 China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences Tianjin Airport Economic Area Tianjin 300308 China
| | - Chunlai Chen
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University Haidian District Beijing 100084 China
| | - Jin-Peng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University 44 Wenhua Xi Road Jinan 250012 Shandong China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education Haidian District Beijing 100191 China
| | - Jiangyun Wang
- Institute of Biophysics, Chinese Academy of Sciences Chaoyang District Beijing 100101 China
- University of the Chinese Academy of Sciences (UCAS) Shijingshan District Beijing 100049 China
- Shenzhen Institute of Transfusion Medicine, Shenzhen Blood Center Futian District Shenzhen 518052 China
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17
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Nanopore-mediated protein delivery enabling three-color single-molecule tracking in living cells. Proc Natl Acad Sci U S A 2021; 118:2012229118. [PMID: 33495347 DOI: 10.1073/pnas.2012229118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Multicolor single-molecule tracking (SMT) provides a powerful tool to mechanistically probe molecular interactions in living cells. However, because of the limitations in the optical and chemical properties of currently available fluorophores and the multiprotein labeling strategies, intracellular multicolor SMT remains challenging for general research studies. Here, we introduce a practical method employing a nanopore-electroporation (NanoEP) technique to deliver multiple organic dye-labeled proteins into living cells for imaging. It can be easily expanded to three channels in commercial microscopes or be combined with other in situ labeling methods. Utilizing NanoEP, we demonstrate three-color SMT for both cytosolic and membrane proteins. Specifically, we simultaneously monitored single-molecule events downstream of EGFR signaling pathways in living cells. The results provide detailed resolution of the spatial localization and dynamics of Grb2 and SOS recruitment to activated EGFR along with the resultant Ras activation.
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18
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Antenna Protein Clustering In Vitro Unveiled by Fluorescence Correlation Spectroscopy. Int J Mol Sci 2021; 22:ijms22062969. [PMID: 33804002 PMCID: PMC8000295 DOI: 10.3390/ijms22062969] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 12/26/2022] Open
Abstract
Antenna protein aggregation is one of the principal mechanisms considered effective in protecting phototrophs against high light damage. Commonly, it is induced, in vitro, by decreasing detergent concentration and pH of a solution of purified antennas; the resulting reduction in fluorescence emission is considered to be representative of non-photochemical quenching in vivo. However, little is known about the actual size and organization of antenna particles formed by this means, and hence the physiological relevance of this experimental approach is questionable. Here, a quasi-single molecule method, fluorescence correlation spectroscopy (FCS), was applied during in vitro quenching of LHCII trimers from higher plants for a parallel estimation of particle size, fluorescence, and antenna cluster homogeneity in a single measurement. FCS revealed that, below detergent critical micelle concentration, low pH promoted the formation of large protein oligomers of sizes up to micrometers, and therefore is apparently incompatible with thylakoid membranes. In contrast, LHCII clusters formed at high pH were smaller and homogenous, and yet still capable of efficient quenching. The results altogether set the physiological validity limits of in vitro quenching experiments. Our data also support the idea that the small, moderately quenching LHCII oligomers found at high pH could be relevant with respect to non-photochemical quenching in vivo.
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19
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Zhang W, Bertinetti L, Blank KG, Dimova R, Gao C, Schneck E, Fratzl P. Spatiotemporal Measurement of Osmotic Pressures by FRET Imaging. Angew Chem Int Ed Engl 2021; 60:6488-6495. [PMID: 33188706 PMCID: PMC7986915 DOI: 10.1002/anie.202011983] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/06/2020] [Indexed: 12/21/2022]
Abstract
Osmotic pressures (OPs) play essential roles in biological processes and numerous technological applications. However, the measurement of OP in situ with spatiotemporal resolution has not been achieved so far. Herein, we introduce a novel kind of OP sensor based on liposomes loaded with water-soluble fluorescent dyes exhibiting resonance energy transfer (FRET). The liposomes experience volume changes in response to OP due to water outflux. The FRET efficiency depends on the average distance between the entrapped dyes and thus provides a direct measure of the OP surrounding each liposome. The sensors exhibit high sensitivity to OP in the biologically relevant range of 0-0.3 MPa in aqueous solutions of salt, small organic molecules, and macromolecules. With the help of FRET microscopy, we demonstrate the feasibility of spatiotemporal OP imaging, which can be a promising new tool to investigate phenomena involving OPs and their dynamics in biology and technology.
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Affiliation(s)
- Wenbo Zhang
- Department of BiomaterialsMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
| | - Luca Bertinetti
- Department of BiomaterialsMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
| | - Kerstin G. Blank
- Mechano(bio)chemistryMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
| | - Rumiana Dimova
- Department of Theory & Bio-SystemsMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and FunctionalizationDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou310027China
| | - Emanuel Schneck
- Department of BiomaterialsMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
- Department of PhysicsTechnische Universität Darmstadt64289DarmstadtGermany
| | - Peter Fratzl
- Department of BiomaterialsMax Planck Institute of Colloids and Interfaces14476PotsdamGermany
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20
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Zhang W, Bertinetti L, Blank KG, Dimova R, Gao C, Schneck E, Fratzl P. Spatiotemporal Measurement of Osmotic Pressures by FRET Imaging. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202011983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Wenbo Zhang
- Department of Biomaterials Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
| | - Luca Bertinetti
- Department of Biomaterials Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
| | - Kerstin G. Blank
- Mechano(bio)chemistry Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
| | - Rumiana Dimova
- Department of Theory & Bio-Systems Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China
| | - Emanuel Schneck
- Department of Biomaterials Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
- Department of Physics Technische Universität Darmstadt 64289 Darmstadt Germany
| | - Peter Fratzl
- Department of Biomaterials Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany
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21
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Amodeo R, Convertino D, Calvello M, Ceccarelli L, Bonsignore F, Ravelli C, Cattaneo A, Martini C, Luin S, Mitola S, Signore G, Marchetti L. Fluorolabeling of the PPTase-Related Chemical Tags: Comparative Study of Different Membrane Receptors and Different Fluorophores in the Labeling Reactions. Front Mol Biosci 2020; 7:195. [PMID: 32850976 PMCID: PMC7426934 DOI: 10.3389/fmolb.2020.00195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 07/22/2020] [Indexed: 11/13/2022] Open
Abstract
The set-up of an advanced imaging experiment requires a careful selection of suitable labeling strategies and fluorophores for the tagging of the molecules of interest. Here we provide an experimental workflow to allow evaluation of fluorolabeling performance of the chemical tags target of phosphopantetheinyl transferase enzymes (PPTases), once inserted in the sequence of different proteins of interest. First, S6 peptide tag was fused to three different single-pass transmembrane proteins (the tyrosine receptor kinases TrkA and VEGFR2 and the tumor necrosis factor receptor p75NTR), providing evidence that all of them can be conveniently albeit differently labeled. Moreover, we chose the S6-tagged TrkA construct to test eight different organic fluorophores for the PPTase labeling of membrane receptors in living cells. We systematically compared their non-specific internalization when added to a S6-tag negative cell culture, the percentage of S6-TrkA expressing cells effectively labeled and the relative mean fluorescence intensity, their photostability upon conjugation, and ratio of specific (cellular) versus background (glass-adhered) signal. This allowed to identify which fluorophores are actually recommended for these labeling reactions. Finally, we compared the PPTase labeling of a purified, YBBR-tagged Nerve Growth Factor with two differently charged organic dyes. We detected some batch-to-batch variability in the labeling yield, regardless of the fluorophore used. However, upon purification of the fluorescent species and incubation with living primary DRG neurons, no significant difference could be appreciated in both internalization and axonal transport of the labeled neurotrophins.
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Affiliation(s)
- Rosy Amodeo
- NEST, Scuola Normale Superiore, Pisa, Italy.,Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | - Domenica Convertino
- NEST, Scuola Normale Superiore, Pisa, Italy.,Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | | | - Lorenzo Ceccarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy.,Dipartimento di Farmacia, Università di Pisa, Pisa, Italy
| | | | - Cosetta Ravelli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | | | | | - Stefano Luin
- NEST, Scuola Normale Superiore, Pisa, Italy.,CNR-NANO, Pisa, Italy
| | - Stefania Mitola
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Giovanni Signore
- NEST, Scuola Normale Superiore, Pisa, Italy.,Fondazione Pisana per la Scienza Onlus, Pisa, Italy
| | - Laura Marchetti
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy.,Dipartimento di Farmacia, Università di Pisa, Pisa, Italy
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22
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Non-cooperative 4E-BP2 folding with exchange between eIF4E-binding and binding-incompatible states tunes cap-dependent translation inhibition. Nat Commun 2020; 11:3146. [PMID: 32561718 PMCID: PMC7305185 DOI: 10.1038/s41467-020-16783-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 05/15/2020] [Indexed: 12/24/2022] Open
Abstract
Phosphorylation of intrinsically disordered eIF4E binding proteins (4E-BPs) regulates cap-dependent translation by weakening their ability to compete with eIF4G for eIF4E binding within the translation initiation complex. We previously showed that phosphorylation of T37 and T46 in 4E-BP2 induces folding of a four-stranded beta-fold domain, partially sequestering the canonical eIF4E-binding helix. The C-terminal intrinsically disordered region (C-IDR), remaining disordered after phosphorylation, contains the secondary eIF4E-binding site and three other phospho-sites, whose mechanisms in inhibiting binding are not understood. Here we report that the domain is non-cooperatively folded, with exchange between beta strands and helical conformations. C-IDR phosphorylation shifts the conformational equilibrium, controlling access to eIF4E binding sites. The hairpin turns formed by pT37/pT46 are remarkably stable and function as transplantable units for phospho-regulation of stability. These results demonstrate how non-cooperative folding and conformational exchange leads to graded inhibition of 4E-BP2:eIF4E binding, shifting 4E-BP2 into an eIF4E binding-incompatible conformation and regulating translation initiation. Phosphorylation of eIF4E binding proteins (4E-BPs) controls their folding and regulates cap-dependent translation. Here, the authors show that phosphorylation of the C-terminal disordered region stabilizes the non-cooperatively folded 4E-BP domain to an eIF4E binding-incompatible state to control translation.
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23
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Knox SL, Steinauer A, Alpha-Cobb G, Trexler A, Rhoades E, Schepartz A. Quantification of protein delivery in live cells using fluorescence correlation spectroscopy. Methods Enzymol 2020; 641:477-505. [PMID: 32713536 DOI: 10.1016/bs.mie.2020.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Fluorescence correlation spectroscopy (FCS) is a quantitative single-molecule method that measures the concentration and rate of diffusion of fluorophore-tagged molecules, both large and small, in vitro and within live cells, and even within discrete cellular compartments. FCS is exceptionally well-suited to directly quantify the efficiency of intracellular protein delivery-specifically, how well different "cell-penetrating" proteins and peptides guide proteinaceous materials into the cytosol and nuclei of live mammalian cells. This article provides an overview of the procedures necessary to execute robust FCS experiments and evaluate endosomal escape efficiencies: preparation of fluorophore-tagged proteins, incubation with mammalian cells and preparation of FCS samples, setup and execution of an FCS experiment, and a detailed discussion of and custom MATLAB® script for analyzing the resulting autocorrelation curves in the context of appropriate diffusion models.
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Affiliation(s)
- Susan L Knox
- Department of Chemistry, University of California, Berkeley, CA, United States
| | - Angela Steinauer
- Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Garrett Alpha-Cobb
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States
| | - Adam Trexler
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Alanna Schepartz
- Department of Chemistry, University of California, Berkeley, CA, United States; Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States.
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24
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Extended Experimental Inferential Structure Determination Method in Determining the Structural Ensembles of Disordered Protein States. Commun Chem 2020; 3:74. [PMID: 32775701 PMCID: PMC7409953 DOI: 10.1038/s42004-020-0323-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Proteins with intrinsic or unfolded state disorder comprise a new frontier in structural biology, requiring the characterization of diverse and dynamic structural ensembles. We introduce a comprehensive Bayesian framework, the Extended Experimental Inferential Structure Determination (X-EISD) method, that calculates the maximum log-likelihood of a disordered protein ensemble. X-EISD accounts for the uncertainties of a range of experimental data and back-calculation models from structures, including NMR chemical shifts, J-couplings, Nuclear Overhauser Effects (NOEs), paramagnetic relaxation enhancements (PREs), residual dipolar couplings (RDCs), hydrodynamic radii (R h ), single molecule fluorescence Förster resonance energy transfer (smFRET) and small angle X-ray scattering (SAXS). We apply X-EISD to the joint optimization against experimental data for the unfolded drkN SH3 domain and find that combining a local data type, such as chemical shifts or J-couplings, paired with long-ranged restraints such as NOEs, PREs or smFRET, yields structural ensembles in good agreement with all other data types if combined with representative IDP conformers.
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25
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Lam K, Tajkhorshid E. Membrane Interactions of Cy3 and Cy5 Fluorophores and Their Effects on Membrane-Protein Dynamics. Biophys J 2020; 119:24-34. [PMID: 32533943 DOI: 10.1016/j.bpj.2020.05.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/28/2020] [Accepted: 05/11/2020] [Indexed: 10/24/2022] Open
Abstract
Organic fluorophores, such as Cy3 and Cy5, have been widely used as chemical labels to probe the structure and dynamics of membrane proteins. Although a number of previous studies have reported on the possibility of some of the water-soluble fluorophores to interact with lipid bilayers, detailed fluorophore-lipid interactions and, more importantly, the potential effect of such interactions on the natural dynamics of the labeled membrane proteins have not been well studied. We have performed a large set of all-atom molecular dynamics simulations employing the highly mobile membrane mimetic model to describe spontaneous partitioning of the fluorophores into lipid bilayers with different lipid compositions. Spontaneous membrane partitioning of Cy3 and Cy5 fluorophores captured in these simulations proceeds in two steps. Electrostatic interaction between the fluorophores and the lipid headgroups facilitates the initial, fast membrane association of the fluorophores, followed by slow insertion of hydrophobic moieties into the lipid bilayer core. After the conversion of the resulting membrane-bound systems to full-membrane representations, biased-exchange umbrella sampling simulations are performed for free energy calculations, revealing a higher energy barrier for partitioning into negatively charged (phosphatidylserine or phosphatidylcholine) membranes than purely zwitterionic (phosphatidylcholine or phosphatidylethanolamine) ones. Furthermore, the potential effect of fluorophore-lipid interactions on membrane proteins has been examined by covalently linking Cy5 to single- and multipass transmembrane helical proteins. Equilibrium simulations show strong position-dependent effects of Cy5-tagging on the structure and natural dynamics of membrane proteins. Interactions between the tagged protein and Cy5 were also observed. Our results suggest that fluorophore-lipid interactions can affect the structure and dynamics of membrane proteins to various extents, especially in systems with higher structural flexibility.
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Affiliation(s)
- Kin Lam
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
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26
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Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
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Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
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Ahmed SM, Nishida-Fukuda H, Li Y, McDonald WH, Gradinaru CC, Macara IG. Exocyst dynamics during vesicle tethering and fusion. Nat Commun 2018; 9:5140. [PMID: 30510181 PMCID: PMC6277416 DOI: 10.1038/s41467-018-07467-5] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/01/2018] [Indexed: 11/15/2022] Open
Abstract
The exocyst is a conserved octameric complex that tethers exocytic vesicles to the plasma membrane prior to fusion. Exocyst assembly and delivery mechanisms remain unclear, especially in mammalian cells. Here we tagged multiple endogenous exocyst subunits with sfGFP or Halo using Cas9 gene-editing, to create single and double knock-in lines of mammary epithelial cells, and interrogated exocyst dynamics by high-speed imaging and correlation spectroscopy. We discovered that mammalian exocyst is comprised of tetrameric subcomplexes that can associate independently with vesicles and plasma membrane and are in dynamic equilibrium with octamer and monomers. Membrane arrival times are similar for subunits and vesicles, but with a small delay (~80msec) between subcomplexes. Departure of SEC3 occurs prior to fusion, whereas other subunits depart just after fusion. About 9 exocyst complexes are associated per vesicle. These data reveal the mammalian exocyst as a remarkably dynamic two-part complex and provide important insights into assembly/disassembly mechanisms. Exocyst complex tethers vesicles to plasma membranes, but assembly mechanisms remain unclear. Here, the authors use Cas9 gene editing to tag exocyst components in epithelial cells, and find that exocyst subcomplexes are recruited to membranes independently, but are both needed for vesicle fusion.
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Affiliation(s)
- Syed Mukhtar Ahmed
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.
| | - Hisayo Nishida-Fukuda
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.,Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 7910295, Japan.,Department of Hepato-Biliary-Pancreatic and Breast Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, 7910295, Japan.,Department of Genome Editing, Institute of Biomedical Sciences, Kansai Medical University, Hirakata, 5731010, Japan
| | - Yuchong Li
- Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada.,Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - W Hayes McDonald
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada.,Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.
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Li Y, Shivnaraine RV, Huang F, Wells JW, Gradinaru CC. Ligand-Induced Coupling between Oligomers of the M 2 Receptor and the G i1 Protein in Live Cells. Biophys J 2018; 115:881-895. [PMID: 30131171 DOI: 10.1016/j.bpj.2018.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/23/2018] [Accepted: 08/02/2018] [Indexed: 02/07/2023] Open
Abstract
Uncertainty over the mechanism of signaling via G protein-coupled receptors (GPCRs) relates in part to questions regarding their supramolecular structure. GPCRs and heterotrimeric G proteins are known to couple as monomers under various conditions. Many GPCRs form oligomers under many of the same conditions, however, and the biological role of those complexes is unclear. We have used dual-color fluorescence correlation spectroscopy to identify oligomers of the M2 muscarinic receptor and of Gi1 in purified preparations and live Chinese hamster ovary cells. Measurements on differently tagged receptors (i.e., eGFP-M2 and mCherry-M2) and G proteins (i.e., eGFP-Gαi1β1γ2 and mCherry-Gαi1β1γ2) detected significant cross-correlations between the two fluorophores in each case, both in detergent micelles and in live cells, indicating that both the receptor and Gi1 can exist as homo-oligomers. Oligomerization of differently tagged Gi1 decreased upon the activation of co-expressed wild-type M2 receptor by an agonist. Measurements on a tagged M2 receptor (M2-mCherry) and eGFP-Gαi1β1γ2 co-expressed in live cells detected cross-correlations only in the presence of an agonist, which therefore promoted coupling of the receptor and the G protein. The effect of the agonist was retained when a fluorophore-tagged receptor lacking the orthosteric site (i.e., M2(D103A)-mCherry) was co-expressed with the wild-type receptor and eGFP-Gαi1β1γ2, indicating that the ligand acted via an oligomeric receptor. Our results point to a model in which an agonist promotes transient coupling of otherwise independent oligomers of the M2 receptor on the one hand and of Gi1 on the other and that an activated complex leads to a reduction in the oligomeric size of the G protein. They suggest that GPCR-mediated signaling proceeds, at least in part, via oligomers.
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Affiliation(s)
- Yuchong Li
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Rabindra V Shivnaraine
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Fei Huang
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.
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Zhi Z, Hasan IY, Mechler A. Formation of Alkanethiol Supported Hybrid Membranes Revisited. Biotechnol J 2018; 13:e1800101. [PMID: 30007019 DOI: 10.1002/biot.201800101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 07/05/2018] [Indexed: 11/09/2022]
Abstract
A phospholipid monolayer supported on an alkanethiol self-assembled monolayer (SAM) constitutes a supported hybrid membrane, a model of biological membranes optimized for electronic access through the underlying metal support surface. It is believed that phospholipids, when deposited from aqueous liposome suspension, spontaneously cover the alkanethiol-modified surface, owing to the reduction of surface free energy of the hydrophobic alkane surface exposed to the solution. However, the formation of the hybrid layer has to overcome significant energy barriers in rupturing the vesicle and "unzipping" the membrane leaflets; hence drivers of the spontaneous hybrid membrane formation are unclear. In this work, the authors studied the efficiency of the liposome deposition method to form hybrid membranes on octanethiol and hexadecanethiol SAMs in aqueous environment. Using quartz crystal microbalance to monitor the deposition process it was found that the hybrid membrane did not form spontaneously; the deposit was dominated by hemi-fused liposomes that can only be removed by applying osmotic stress. However, osmotic stress yielded a reproducible layer characterized by ≈-5Hz frequency change that is also confirmed by fluorescence microscopy imaging, irrespective of lipid concentration and the chain length of the SAMs. The frequency change is ≈20% of the frequency change expected for a tightly bound bilayer membrane, or 40% of a single leaflet, suggesting that the lipid layer is in a different conformation compared to a bilayer membrane: the acyl chains are most likely parallel to the SAM surface, likely due to strong hydrophobic interaction. Comparing these results to the literature it appears that the initial formation of hybrid membranes is inhibited by the ionic environment, while osmotic stress leads to the observed unique layer conformation.
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Affiliation(s)
- Zelun Zhi
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Imad Y Hasan
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Adam Mechler
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
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