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Batta Á, Hajdu T, Nagy P. Improved estimation of the ratio of detection efficiencies of excited acceptors and donors for FRET measurements. Cytometry A 2023. [PMID: 36866503 DOI: 10.1002/cyto.a.24728] [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: 12/09/2022] [Revised: 02/02/2023] [Accepted: 02/28/2023] [Indexed: 03/04/2023]
Abstract
Förster resonance energy transfer (FRET) is a radiationless interaction between a donor and an acceptor whose distance dependence makes it a sensitive tool for studying the oligomerization and the structure of proteins. When FRET is determined by measuring the sensitized emission of the acceptor, a parameter characterizing the ratio of detection efficiencies of an excited acceptor versus an excited donor is invariably involved in the formalism. For FRET measurements involving fluorescent antibodies or other external labels, this parameter, designated by α, is usually determined by comparing the intensity of a known number of donors and acceptors in two independent samples leading to a large statistical variability if the sample size is small. Here, we present a method that improves precision by applying microbeads with a calibrated number of antibody binding sites and a donor-acceptor mixture in which donors and acceptors are present in a certain, experimentally determined ratio. A formalism is developed for determining α and the superior reproducibility of the proposed method compared to the conventional approach is demonstrated. Since the novel methodology does not require sophisticated calibration samples or special instrumentation, it can be widely applied for the quantification of FRET experiments in biological research.
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Affiliation(s)
- Ágnes Batta
- Faculty of Medicine, Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary.,Faculty of Medicine, Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Tímea Hajdu
- Faculty of Medicine, Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Faculty of Medicine, Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary
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Abstract
This unit describes the basic principles of Förster resonance energy transfer (FRET). Beginning with a brief summary of the history of FRET applications, the theory of FRET is introduced in detail using figures to explain all the important parameters of the FRET process. After listing various approaches for measuring FRET efficiency, several pieces of advice are given on choosing the appropriate instrumentation. The unit concludes with a discussion of the limitations of FRET measurements followed by a few examples of the latest FRET applications, including new developments such as spectral flow cytometric FRET, single-molecule FRET, and combinations of FRET with super-resolution or lifetime imaging microscopy and with molecular dynamics simulations. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Ágnes Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Szöllősi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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3
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Batta G, Hajdu T, Nagy P. Characterization of the Effect of Sphingolipid Accumulation on Membrane Compactness, Dipole Potential, and Mobility of Membrane Components. Methods Mol Biol 2021; 2187:283-301. [PMID: 32770513 DOI: 10.1007/978-1-0716-0814-2_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Communication between cells and their environment is carried out through the plasma membrane including the action of most pharmaceutical drugs. Although such a communication typically involves specific binding of a messenger to a membrane receptor, the biophysical state of the lipid bilayer strongly influences the outcome of this interaction. Sphingolipids constitute an important part of the lipid membrane, and their mole fraction modifies the biophysical characteristics of the membrane. Here, we describe methods that can be used for measuring how sphingolipid accumulation alters the compactness, microviscosity, and dipole potential of the lipid bilayer and the mobility of membrane components.
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Affiliation(s)
- Gyula Batta
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Tímea Hajdu
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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Menaesse A, Sumetsky D, Emanuely N, Stein JL, Gates EM, Hoffman BD, Boustany NN. Simplified Instrument Calibration for Wide-Field Fluorescence Resonance Energy Transfer (FRET) Measured by the Sensitized Emission Method. Cytometry A 2020; 99:407-416. [PMID: 32700451 DOI: 10.1002/cyto.a.24194] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/30/2020] [Accepted: 07/17/2020] [Indexed: 12/21/2022]
Abstract
Fӧrster (or fluorescence) resonance energy transfer (FRET) is a quantifiable energy transfer in which a donor fluorophore nonradiatively transfers its excitation energy to an acceptor fluorophore. A change in FRET efficiency indicates a change of proximity and environment of these fluorophores, which enables the study of intermolecular interactions. Measurement of FRET efficiency using the sensitized emission method requires a donor-acceptor calibrated system. One of these calibration factors named the G factor, which depends on instrument parameters related to the donor and acceptor measurement channels and on the fluorophores quantum efficiencies, can be determined in several different ways and allows for conversion of the raw donor and acceptor emission signals to FRET efficiency. However, the calculated value of the G factor from experimental data can fluctuate significantly depending on the chosen experimental method and the size of the sample. In this technical note, we extend the results of Gates et al. (Cytometry Part A 95A (2018) 201-213) by refining the calibration method used for calibration of FRET from image pixel data. Instead of using the pixel histograms of two constructs with high and low FRET efficiency to determine the G factor, we use pixel histogram data from one construct of known efficiency. We validate this method by determining the G factor with the same constructs developed and used by Gates et al. and comparing the results from the two approaches. While the two approaches are equivalent theoretically, we demonstrate that the use of a single construct with known efficiency provides a more precise experimental measurement of the G factor that can be attained by collecting a smaller number of images. © 2020 International Society for Advancement of Cytometry.
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Affiliation(s)
- Audrey Menaesse
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA.,School of Life Sciences Engineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Daniel Sumetsky
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA
| | - Nicolas Emanuely
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA.,Institut d'Optique Graduate School, Palaiseau, France
| | - Jeremy L Stein
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA
| | - Evan M Gates
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Nada N Boustany
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA
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Szabó Á, Nagy P. I Am the Alpha and the …Gamma, and the G. Calibration of Intensity-Based FRET Measurements. Cytometry A 2020; 99:369-371. [PMID: 32790096 DOI: 10.1002/cyto.a.24206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/05/2020] [Accepted: 08/10/2020] [Indexed: 12/22/2022]
Affiliation(s)
- Ágnes Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Peter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Szabó Á, Szendi-Szatmári T, Szöllősi J, Nagy P. Quo vadis FRET? Förster's method in the era of superresolution. Methods Appl Fluoresc 2020; 8:032003. [PMID: 32521530 DOI: 10.1088/2050-6120/ab9b72] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although the theoretical foundations of Förster resonance energy transfer (FRET) were laid in the 1940s as part of the quantum physical revolution of the 20th century, it was only in the 1970s that it made its way to biology as a result of the availability of suitable measuring and labeling technologies. Thanks to its ease of application, FRET became widely used for studying molecular associations on the nanometer scale. The development of superresolution techniques at the turn of the millennium promised an unprecedented insight into the structure and function of molecular complexes. Without downplaying the significance of superresolution microscopies this review expresses our view that FRET is still a legitimate tool in the armamentarium of biologists for studying molecular associations since it offers distinct advantages and overcomes certain limitations of superresolution approaches.
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Affiliation(s)
- Ágnes Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem square 1, 4032 Debrecen, Hungary. MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem square 1, 4032 Debrecen, Hungary
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Mohajeri N, Imani M, Akbarzadeh A, Sadighi A, Zarghami N. An update on advances in new developing DNA conjugation diagnostics and ultra-resolution imaging technologies: Possible applications in medical and biotechnological utilities. Biosens Bioelectron 2019; 144:111633. [DOI: 10.1016/j.bios.2019.111633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 12/15/2022]
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