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Forster resonance energy transfer

David Llères, Aymeric P Bailly, Aurélien Perrin, David G Norman, Dimitris P Xirodimas, Robert Feil
How metazoan genomes are structured at the nanoscale in living cells and tissues remains unknown. Here, we adapted a quantitative FRET (Förster resonance energy transfer)-based fluorescence lifetime imaging microscopy (FLIM) approach to assay nanoscale chromatin compaction in living organisms. Caenorhabditis elegans was chosen as a model system. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells...
February 14, 2017: Cell Reports
Jung-Hwa Cho, Carter J Swanson, Jeannie Chen, Ang Li, Lisa G Lippert, Shannon E Boye, Kasey Rose, Sivaraj Sivaramakrishnan, Cheng-Ming Chuong, Robert H Chow
We report on GCaMP-Rs, a new family of genetically encoded ratiometric calcium indicators that extend the virtues of the GCaMP proteins to ratiometric measurements. We have engineered a tandem construct of calcium-dependent GCaMP and calcium-independent mCherry fluorescent proteins. The tandem design assures that the two proteins localize in the same cellular compartment(s) and facilitates pixelwise ratiometric measurements; however, Förster resonance energy transfer (FRET) between the fluorophores reduces brightness of the sensor by up to half (depending on the GCaMP variant)...
February 14, 2017: ACS Chemical Biology
Igor Nabiev, Regina S Bilan, Viktor A Krivenkov, Mikhail A Berestovoy, Anton Efimov, Igor I Agapov, Pavel S Samokhvalov, Alyona V Sukhanova
Quantum dot (QD)-encoded microbeads are emerging for multiplexed analysis of biological markers. Quantitative encoding of the microbeads prepared with the different concentrations of QDs of different colors suffers from the resonance energy transfer from the QDs fluorescing at the shorter wavelengths to the QDs fluorescing at the longer wavelengths. Here, we have used the layer-by-layer deposition technique to spatially separate QDs of different colors with several polymer layers, so that the distance between them would be larger than the Förster energy transfer radius...
February 13, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Antonio Tirado-Guizar, Francisco Paraguay-Delgado, Georgina E Pina-Luis
A new 'turn-on' Förster resonance energy transfer (FRET) nanosensor for l-tryptophan based on molecularly imprinted quantum dots (QDs) is proposed. The approach combines the advantages of the molecular imprinting technique, the fluorescent characteristics of the QDs and the energy transfer process. Silica-coated CdTe QDs were first synthesized and then molecularly imprinted using a sol-gel process without surfactants. The final composite presents stable fluorescence which increases with the addition of l-tryptophan...
November 17, 2016: Methods and Applications in Fluorescence
Michelle R Sorkin, Joshua A Walker, Joseph S Brown, Christopher A Alabi
Cleavable and heteromultifunctional crosslinkers have proven critical in a wide range of biological applications. Traditional approaches for synthesizing these linkers suffer from various synthetic and functional limitations. In this work, an efficient sequence-defined synthetic methodology, developed for the assembly of oligothioetheramides, was used to address many of these limitations. Four heterotrifunctional crosslinkers with up to two orthogonal internal cleavage sites were synthesized. These linkers were conjugated to a pair of fluorophores that undergo Förster resonance energy transfer (FRET) and a model protein - human transferrin...
February 13, 2017: Bioconjugate Chemistry
Simina Ticau, Larry J Friedman, Kanokwan Champasa, Ivan R Corrêa, Jeff Gelles, Stephen P Bell
The opening and closing of two ring-shaped Mcm2-7 DNA helicases is necessary to license eukaryotic origins of replication, although the mechanisms controlling these events are unclear. The origin-recognition complex (ORC), Cdc6 and Cdt1 facilitate this process by establishing a topological link between each Mcm2-7 hexamer and origin DNA. Using colocalization single-molecule spectroscopy and single-molecule Förster resonance energy transfer (FRET), we monitored ring opening and closing of Saccharomyces cerevisiae Mcm2-7 during origin licensing...
February 13, 2017: Nature Structural & Molecular Biology
Adam Langlois, Jean-Michel Camus, Paul-Ludovic Karsenti, Roger Guilard, Pierre D Harvey
The demetalation of a precursor dyad, 3, built upon a zinc(II)-containing artificial special pair and free-base antenna, leads to a new dyad, 4, for singlet energy transfer composed of cofacial free-base porphyrins (acceptor), [Fb]2 bridged by a 1,4-C6H4 group to a free-base antenna (donor), [Fb]. This dyad exhibits the general structure [M]2-C6H4-[Fb], where [M]2 = [Fb]2, and completes a series reported earlier, where [M]2 = [Mg]2 (2) and [Zn]2 (3). The latter dyads exhibit a bidirectional energy-transfer process at 298 K for 2 and at 77 K for 3...
February 13, 2017: Inorganic Chemistry
Sreenadh Sasidharan Pillai, Hiroshi Yukawa, Daisuke Onoshima, Vasudevanpillai Biju, Yoshinobu Baba
The steady state and time-resolved photoluminescence quenching of streptavidin modified CdSe/ZnS quantum dots (QDs) instigated by biotin-peptide-BHQ-1 (biotin-pep-BHQ-1) molecule was investigated. Here, we have achieved an efficient photoluminescence (PL) quenching of QDs with the conjugation of dark quencher (black hole quencher-BHQ) molecules intermediated with the GPLGVRGK peptide. The luminescence of streptavidin-QDs585 was decreased upon titration with a nano molar concentration of the biotin-GPLGVRGK-BHQ-1 molecule...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Christopher King, Valerica Raicu, Kalina Hristova
Forster Resonant Energy Transfer (FRET) is an indispensable experimental tool for studying membrane proteins. Currently, two models are available for researchers to determine the oligomerization state of membrane proteins in a static quenching FRET experiment: the model of Veatch and Stryer derived in 1977, and the Kinetic Theory-based model for intra-oligomeric FRET, derived in 2007. Because of confinement in two-dimensions, a substantial amount of FRET is generated by energy transfer between fluorophores located in separate oligomers in the 2-D bilayer...
February 9, 2017: Journal of Biological Chemistry
Meral Tunc-Ozdemir, Alan M Jones
BACKGROUND: Arabidopsis, 7-transmembrane Regulator of G signaling protein 1 (AtRGS1) modulates canonical G protein signaling by promoting the inactive state of heterotrimeric G protein complex on the plasma membrane. It is known that plant leucine-rich repeat receptor-like kinases (LRR RLKs) phosphorylate AtRGS1 in vitro but little is known about the in vivo interaction, molecular dynamics, or the cellular consequences of this interaction. METHODS: Therefore, a subset of the known RLKs that phosphorylate AtRGS1 were selected for elucidation, namely, BAK1, BIR1, FLS2...
2017: PloS One
Xin-Xiang Lim, Arun Chandramohan, Xin Ying Elisa Lim, Nirmalya Bag, Kamal Kant Sharma, Melissa Wirawan, Thorsten Wohland, Shee-Mei Lok, Ganesh S Anand
Dengue virus serotype 2 (DENV2) alone undergoes structural expansion at 37 °C (associated with host entry), despite high sequence and structural homology among the four known serotypes. The basis for this differential expansion across strains and serotypes is unknown and necessitates mapping of the dynamics of dengue whole viral particles to describe their coordinated motions and conformational changes when exposed to host-like environments. Here we capture the dynamics of intact viral particles of two serotypes, DENV1 and DENV2, by amide hydrogen/deuterium exchange mass spectrometry (HDXMS) and time resolved Förster Resonance Energy Transfer...
February 10, 2017: Nature Communications
Cristian R Smulski, Marion Decossas, Neila Chekkat, Julien Beyrath, Laure Willen, Gilles Guichard, Raquel Lorenzetti, Marta Rizzi, Hermann Eibel, Pascal Schneider, Sylvie Fournel
TNF receptor superfamily members (TNFRSF) such as CD40, Fas and TRAIL receptor 2 (TRAILR2) participate to the adaptive immune response by eliciting survival, proliferation, differentiation and/or cell death signals. The balance between these signals determines the fate of the immune response. It was previously reported that these receptors are able to self-assemble in the absence of ligand through their extracellular regions. However, the role of this oligomerization is not well understood, and none of the proposed hypotheses take into account potential hetero-association of receptors...
February 9, 2017: Cell Death & Disease
Olga Mazina, Anni Allikalt, Juha S Tapanainen, Andres Salumets, Ago Rinken
Determination of biological activity of gonadotropin hormones is essential in reproductive medicine and pharmaceutical manufacturing of the hormonal preparations. The aim of the study was to adopt a G-protein coupled receptor (GPCR)-mediated signal transduction pathway based assay for quantification of biological activity of gonadotropins. We focussed on studying human chorionic gonadotropin (hCG) and follicle-stimulating hormone (FSH), as these hormones are widely used in clinical practice. Receptor-specific changes in cellular cyclic adenosine monophosphate (cAMP, second messenger in GPCR signalling) were monitored by a Förster resonance energy transfer (FRET) biosensor protein (T)Epac(VV) in living cells upon activation of the relevant gonadotropin receptor...
February 9, 2017: Scientific Reports
Yasser Gidi, Matthias Götte, Gonzalo Cosa
Förster resonance energy transfer (FRET)-based single molecule techniques have revolutionized our understanding of conformational dynamics in biomolecular systems. Recently a new single molecule technique based on protein-induced fluorescence enhancement (PIFE) has aided studies where minimal (<3nm) displacements occur. Concerns have been raised regarding whether donor fluorophore intensity (and correspondingly emission quantum yield) fluctuations, intrinsic to PIFE methods, may adversely affect FRET studies when retrieving the donor-acceptor dye distance...
February 8, 2017: Journal of Physical Chemistry. B
S Palantavida, B Peng, I Sokolov
We report on a novel approach to synthesize ultrabright fluorescent silica particles capable of producing a large number of complex spectra. The spectra can be excited using a single wavelength which is paramount in quantitative fluorescence imaging, flow cytometry and sensing applications. The approach employs the physical encapsulation of organic fluorescent molecules inside a nanoporous silica matrix with no dye leakage. As was recently demonstrated, such an encapsulation allowed for the encapsulation of very high concentrations of organic dyes without quenching their fluorescent efficiency...
February 8, 2017: Nanoscale
Jin-Sil Choi, Soojin Kim, Dongwon Yoo, Tae-Hyun Shin, Hoyoung Kim, Muller D Gomes, Sun Hee Kim, Alexander Pines, Jinwoo Cheon
Nanoscale distance-dependent phenomena, such as Förster resonance energy transfer, are important interactions for use in sensing and imaging, but their versatility for bioimaging can be limited by undesirable photon interactions with the surrounding biological matrix, especially in in vivo systems. Here, we report a new type of magnetism-based nanoscale distance-dependent phenomenon that can quantitatively and reversibly sense and image intra-/intermolecular interactions of biologically important targets. We introduce distance-dependent magnetic resonance tuning (MRET), which occurs between a paramagnetic 'enhancer' and a superparamagnetic 'quencher', where the T1 magnetic resonance imaging (MRI) signal is tuned ON or OFF depending on the separation distance between the quencher and the enhancer...
February 6, 2017: Nature Materials
Soreen Cyphers, Emily F Ruff, Julie M Behr, John D Chodera, Nicholas M Levinson
The catalytic activity of many protein kinases is controlled by conformational changes of a conserved Asp-Phe-Gly (DFG) motif. We used an infrared probe to track the DFG motif of the mitotic kinase Aurora A (AurA) and found that allosteric activation by the spindle-associated protein Tpx2 involves an equilibrium shift toward the active DFG-in state. Förster resonance energy transfer experiments show that the activation loop undergoes a nanometer-scale movement that is tightly coupled to the DFG equilibrium...
February 6, 2017: Nature Chemical Biology
Magdalena Makarska-Bialokoz
The binding interaction between human hemoglobin and uric acid has been studied for the first time, by UV-vis absorption and steady-state, synchronous and three-dimensional fluorescence techniques. Characteristic effects observed for human hemoglobin intrinsic fluorescence during interaction with uric acid at neutral pH point at the formation of stacking non-covalent and non-fluorescent complexes. All the calculated parameters, the binding, fluorescence quenching and bimolecular quenching rate constants, as well as Förster resonance energy transfer parameters confirm the existence of static quenching...
January 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Arturo Ibáñez-Fonseca, Matilde Alonso, Francisco Javier Arias, José Carlos Rodríguez-Cabello
In the last decades, recombinant structural proteins have become very promising in addressing different issues such as the lack of traceability of biomedical devices or the design of more sensitive biosensors. Among them, we find elastin-like recombinamers (ELRs), which can be designed to self-assemble into diverse structures, such as hydrogels. Furthermore, they might be combined with other protein polymers, such as silk, to give silk-elastin-like recombinamers (SELRs), holding the properties of both proteins...
February 15, 2017: Bioconjugate Chemistry
Jan Schejbal, Lucie Slezáčková, Roman Řemínek, Zdeněk Glatz
In this work a novel capillary electrophoresis-mass spectrometry (CE-MS) based method was developed and validated for the assay of β-secretase (BACE1) activity as a potential target for Alzheimer's disease (AD) treatment. In contrast with the typically used Förster resonance energy transfer (FRET) assays, an unlabelled decapeptide derived from the amyloid precursor protein BACE1 site with the "Swedish mutation" was used as the substrate. The CE usage enabled the enzymatic reaction to be carried out in as small a volume as 100μL in 60min with sufficient yields of proteolytic product, which was subsequently separated in a bare fused silica capillary using 12...
January 23, 2017: Journal of Chromatography. A
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