scholarly journals Proximity-assisted photoactivation (PAPA): Detecting molecular interactions in live-cell single-molecule imaging

2021 ◽  
Author(s):  
Thomas George Wade Graham ◽  
John Joseph Ferrie ◽  
Gina M. Dailey ◽  
Robert Tjian ◽  
Xavier Darzacq
Keyword(s):  
Single Molecule ◽  
Molecular Interactions ◽  
Protein Interactions ◽  
Protein Complexes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Live Cells ◽  
Single Molecule Imaging ◽  
Protein Protein Interactions ◽  
Self Association

Single-molecule imaging provides a powerful way to study biochemical processes in live cells, yet it remains challenging to track single molecules while simultaneously detecting their interactions. Here we describe a novel property of rhodamine dyes, proximity-assisted photoactivation (PAPA), in which one fluorophore (the "sender") can reactivate a second fluorophore (the "receiver") from a dark state. PAPA requires proximity between the two fluorophores, yet it operates at a longer average intermolecular distance than Forster resonance energy transfer (FRET). We show that PAPA can be used in live cells both to detect protein-protein interactions and to highlight a sub-population of labeled protein complexes in which two different labels are in proximity. In proof-of-concept experiments, PAPA detected the expected correlation between androgen receptor self-association and chromatin binding at the single-cell level. These results establish a new way in which a photophysical property of fluorophores can be harnessed to study molecular interactions in single-molecule imaging of live cells.

scholarly journals Monitoring ligand-dependent assembly of receptor ternary complexes in live cells by BRETFect

2018 ◽  
Vol 115 (11) ◽  
pp. E2653-E2662 ◽  
Author(s):  
David Cotnoir-White ◽  
Mohamed El Ezzy ◽  
Pierre-Luc Boulay ◽  
Marieke Rozendaal ◽  
Michel Bouvier ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Protein Interactions ◽  
Protein Complexes ◽  
Unmet Need ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Ternary Complexes ◽  
Live Cells ◽  
Protein Protein Interactions ◽  
Versatile Technique

There is currently an unmet need for versatile techniques to monitor the assembly and dynamics of ternary complexes in live cells. Here we describe bioluminescence resonance energy transfer with fluorescence enhancement by combined transfer (BRETFect), a high-throughput technique that enables robust spectrometric detection of ternary protein complexes based on increased energy transfer from a luciferase to a fluorescent acceptor in the presence of a fluorescent intermediate. Its unique donor–intermediate–acceptor relay system is designed so that the acceptor can receive energy either directly from the donor or indirectly via the intermediate in a combined transfer, taking advantage of the entire luciferase emission spectrum. BRETFect was used to study the ligand-dependent cofactor interaction properties of the estrogen receptors ERα and ERβ, which form homo- or heterodimers whose distinctive regulatory properties are difficult to dissect using traditional methods. BRETFect uncovered the relative capacities of hetero- vs. homodimers to recruit receptor-specific cofactors and regulatory proteins, and to interact with common cofactors in the presence of receptor-specific ligands. BRETFect was also used to follow the assembly of ternary complexes between the V2R vasopressin receptor and two different intracellular effectors, illustrating its use for dissection of ternary protein–protein interactions engaged by G protein-coupled receptors. Our results indicate that BRETFect represents a powerful and versatile technique to monitor the dynamics of ternary interactions within multimeric complexes in live cells.

QUANTITATIVE FRET MEASUREMENT BASED ON CONFOCAL MICROSCOPY IMAGING AND PARTIAL ACCEPTOR PHOTOBLEACHING

2012 ◽  
Vol 05 (03) ◽  
pp. 1250015 ◽  
Author(s):  
XIAO-PING WANG ◽  
HUAI-NA YU ◽  
TONG-SHENG CHEN
Keyword(s):  
Protein Interactions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Region Of Interest ◽  
Living Cells ◽  
Live Cells ◽  
Protein Protein Interactions ◽  
Microscopy Imaging ◽  
Acceptor Photobleaching ◽  
Induced Apoptosis

Fluorescence resonance energy transfer (FRET) technology had been widely used to study protein–protein interactions in living cells. In this study, we developed a ROI-PbFRET method to real-time quantitate the FRET efficiency of FRET construct in living cells by combining the region of interest (ROI) function of confocal microscope and partial acceptor photobleaching. We validated the ROI-PbFRET method using GFPs-based FRET constructs including 18AA and SCAT3, and used it to quantitatively monitor the dynamics of caspase-3 activation in single live cells stably expressing SCAT3 during staurosporine (STS)-induced apoptosis. Our results for the first demonstrate that ROI-PbFRET method is a powerful potential tool for detecting the dynamics of molecular interactions in live cells.

Extended bioluminescence resonance energy transfer (eBRET) for monitoring prolonged protein–protein interactions in live cells

2006 ◽  
Vol 18 (10) ◽  
pp. 1664-1670 ◽  
Author(s):  
Kevin D.G. Pfleger ◽  
Jasmin R. Dromey ◽  
Matthew B. Dalrymple ◽  
Esther M.L. Lim ◽  
Walter G. Thomas ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Protein Interactions ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Live Cells ◽  
Bioluminescence Resonance Energy Transfer ◽  
Protein Protein Interactions

Single-Molecule FRET of Intrinsically Disordered Proteins

2020 ◽  
Vol 71 (1) ◽  
pp. 391-414 ◽  
Author(s):  
Lauren Ann Metskas ◽  
Elizabeth Rhoades
Keyword(s):  
Single Molecule ◽  
Protein Interactions ◽  
Intrinsically Disordered Proteins ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Disordered Proteins ◽  
Protein Protein Interactions ◽  
Cellular Functions ◽  
Intrinsically Disordered ◽  
Single Molecule Fret

Intrinsically disordered proteins (IDPs) are now widely recognized as playing critical roles in a broad range of cellular functions as well as being implicated in diverse diseases. Their lack of stable secondary structure and tertiary interactions, coupled with their sensitivity to measurement conditions, stymies many traditional structural biology approaches. Single-molecule Förster resonance energy transfer (smFRET) is now widely used to characterize the physicochemical properties of these proteins in isolation and is being increasingly applied to more complex assemblies and experimental environments. This review provides an overview of confocal diffusion-based smFRET as an experimental tool, including descriptions of instrumentation, data analysis, and protein labeling. Recent papers are discussed that illustrate the unique capability of smFRET to provide insight into aggregation-prone IDPs, protein–protein interactions involving IDPs, and IDPs in complex experimental milieus.

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