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Forster resonance energy transfer

Yiqun Xue, Jingjing Xing, Yinglang Wan, Xueqin Lv, Lusheng Fan, Yongdeng Zhang, Kai Song, Li Wang, Xiaohua Wang, Xin Deng, Frantisek Baluska, John M Christie, Jinxing Lin
Phototropin (phot)-mediated signaling initiated by blue light (BL) plays a critical role in optimizing photosynthetic light capture at the plasma membrane (PM) in plants. However, the mechanisms underlying the regulation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and step-wise photobleaching analysis we demonstrated that in the dark phot1-GFP proteins remain in an inactive state and mostly present as a monomer. The phot1-GFP diffusion rate and its dimerization increased in a dose-dependent manner in response to BL...
April 21, 2018: Molecular Plant
Samia M El-Gizawy, Noha N Atia, Noha M Hosny
A rapid, simple, selective and precise fluorimetric method was developed and validated for determination of a selective xanthine oxidase inhibitor; febuxostat (FBX) in pharmaceutical formulations and in human plasma. The proposed method is based on quenching effect of FBX on the fluorescence intensity of terbium (Tb3+ ) through fluorescence resonance energy transfer (FRET) from Tb3+ to FBX. The formed complex was measured at λex. 320 nm/λem. 490 nm against a reagent blank. Fluorescence intensity of Tb3+ was diminished when FBX was added...
April 24, 2018: Luminescence: the Journal of Biological and Chemical Luminescence
Daria M Shcherbakova, Natasha Cox Cammer, Tsipora M Huisman, Vladislav V Verkhusha, Louis Hodgson
Direct visualization and light control of several cellular processes is a challenge, owing to the spectral overlap of available genetically encoded probes. Here we report the most red-shifted monomeric near-infrared (NIR) fluorescent protein, miRFP720, and the fully NIR Förster resonance energy transfer (FRET) pair miRFP670-miRFP720, which together enabled design of biosensors compatible with CFP-YFP imaging and blue-green optogenetic tools. We developed a NIR biosensor for Rac1 GTPase and demonstrated its use in multiplexed imaging and light control of Rho GTPase signaling pathways...
April 23, 2018: Nature Chemical Biology
Emma N Bardsley, Harvey Davis, Keith J Buckler, David J Paterson
Single or combinatorial administration of β-blockers is a mainstay treatment strategy for conditions caused by sympathetic overactivity. Conventional wisdom suggests that the main beneficial effect of β-blockers includes resensitization and restoration of β1-adrenergic signaling pathways in the myocardium, improvements in cardiomyocyte contractility, and reversal of ventricular sensitization. However, emerging evidence indicates that another beneficial effect of β-blockers in disease may reside in sympathetic neurons...
April 23, 2018: Hypertension
Taehyung C Lee, Crystal R Moran, Philip A Cistrone, Philip E Dawson, Ashok A Deniz
Single-molecule fluorescence is widely used to study conformational complexity in proteins, and has proven especially valuable with intrinsically disordered proteins (IDPs). Protein studies using dual-color single-molecule Förster resonance energy transfer (smFRET) are now quite common, but many could benefit from simultaneous measurement of multiple distances through multi-color labeling. Such studies, however, have suffered from limitations in site-specific incorporation of more than two dyes per polypeptide...
April 12, 2018: Cell Chemical Biology
Sandra M W van de Wiel, D Rudi de Waart, Ronald P J Oude Elferink, Stan F J van de Graaf
Background & Aims: The organic solute transporter α-β (OSTα-OSTβ) mainly facilitates transport of bile acids across the basolateral membrane of ileal enterocytes. Therefore, inhibition of OSTα-OSTβ might have similar beneficial metabolic effects as intestine-specific agonists of the major nuclear receptor for bile acids, the farnesoid X receptor (FXR). However, no OSTα-OSTβ inhibitors have yet been identified. Methods: Here, we developed a screen to identify specific inhibitors of OSTα-OSTβ using a genetically encoded Förster Resonance Energy Transfer (FRET)-bile acid sensor that enables rapid visualization of bile acid efflux in living cells...
March 2018: Cellular and Molecular Gastroenterology and Hepatology
Syed S Razi, Yun Hee Koo, Woojae Kim, Wenbo Yang, Zhijia Wang, Habtom Gobeze, Francis D'Souza, Jianzhang Zhao, Dongho Kim
A boron dipyrromethane (BDP)-containing Pt(II)-Schiff base complex (Pt-BDP), showing ping-pong singlet-triplet energy transfer, was synthesized, and the detailed photophysical properties were investigated using various steady-state and time-resolved transient spectroscopies. Femtosecond/nanosecond transient absorption spectroscopies demonstrated that, upon selective excitation of the BDP unit in Pt-BDP at 490 nm, Förster resonance energy transfer from the BDP unit to the Pt(II) coordination center occurred (6...
April 19, 2018: Inorganic Chemistry
Francesca Salis, Ana B Descalzo, Elena Benito-Peña, María C Moreno-Bondi, Guillermo Orellana
Fluorescence immunoassays are popular for achieving high sensitivity, but they display limitations in biological samples due to strong absorption of light, background fluorescence from matrix components, or light scattering by the biomacromolecules. A powerful strategy to overcome these problems is introduced here by using fluorescent magnetic nanobeads doped with two boron-dipyrromethane dyes displaying intense emission in the visible and near-infrared regions, respectively. Careful matching of the emission and absorption features of the dopants leads to a virtual Stokes shift larger than 150 nm achieved by an intraparticle Förster resonance energy transfer (FRET) process between the donor and the acceptor dyes...
April 17, 2018: Small
Mario Brameshuber, Florian Kellner, Benedikt K Rossboth, Haisen Ta, Kevin Alge, Eva Sevcsik, Janett Göhring, Markus Axmann, Florian Baumgart, Nicholas R J Gascoigne, Simon J Davis, Hannes Stockinger, Gerhard J Schütz, Johannes B Huppa
T cell antigen recognition requires T cell antigen receptors (TCRs) engaging MHC-embedded antigenic peptides (pMHCs) within the contact region of a T cell with its conjugated antigen-presenting cell. Despite micromolar TCR:pMHC affinities, T cells respond to even a single antigenic pMHC, and higher-order TCRs have been postulated to maintain high antigen sensitivity and trigger signaling. We interrogated the stoichiometry of TCRs and their associated CD3 subunits on the surface of living T cells through single-molecule brightness and single-molecule coincidence analysis, photon-antibunching-based fluorescence correlation spectroscopy and Förster resonance energy transfer measurements...
April 16, 2018: Nature Immunology
Richard Börner, Danny Kowerko, Mélodie C A S Hadzic, Sebastian L B König, Marc Ritter, Roland K O Sigel
Single-molecule microscopy has become a widely used technique in (bio)physics and (bio)chemistry. A popular implementation is single-molecule Förster Resonance Energy Transfer (smFRET), for which total internal reflection fluorescence microscopy is frequently combined with camera-based detection of surface-immobilized molecules. Camera-based smFRET experiments generate large and complex datasets and several methods for video processing and analysis have been reported. As these algorithms often address similar aspects in video analysis, there is a growing need for standardized comparison...
2018: PloS One
Réka Petrovics, Bianka Söveges, Alexandra Egyed, Gergely Knorr, Attila Kormos, Tímea Imre, György Török, András Zeke, Éva Kocsmár, Gábor Lotz, Péter Kele, Krisztina Németh
One of the most popular means to follow interactions between bio(macro)molecules is Förster resonance energy transfer (FRET). There is large interest in widening the selection of fluorescent FRET pairs especially in the region of the red/far red range, where minimal autofluorescence is encountered. A set of bioorthogonally applicable fluorescent dyes, synthesized recently in our lab, were paired (Cy3T/Cy5T; Cy1A/Cy3T and Cy1A/CBRD1A) based on their spectral characteristics in order to test their potential in FRET applications...
April 9, 2018: Organic & Biomolecular Chemistry
T A Masters, N A Robinson, R J Marsh, T S Blacker, D A Armoogum, B Larijani, A J Bain
Time and polarization-resolved stimulated emission depletion (STED) measurements are used to investigate excited state evolution following the two-photon excitation of enhanced green fluorescent protein (EGFP). We employ a new approach for the accurate STED measurement of the hitherto unmeasured degree of hexadecapolar transition dipole moment alignment α40 present at a given excitation-depletion (pump-dump) pulse separation. Time-resolved polarized fluorescence measurements as a function of pump-dump delay reveal the time evolution of α40 to be considerably more rapid than predicted for isotropic rotational diffusion in EGFP...
April 7, 2018: Journal of Chemical Physics
Anoop Rawat, Barun Kumar Maity, Bappaditya Chandra, Sudipta Maiti
Islet amyloid polypeptide (IAPP) is a 37 residue intrinsically disordered protein whose aggregation is associated with Type II diabetes. Like most amyloids, it appears that the intermediate aggregates ("oligomers") of IAPP are more toxic than the mature fibrils, and interaction with the cell membrane is likely to be an integral component of the toxicity. Here we probe the membrane affinity and the conformation of the peptide as a function of its aggregation state. We find that the affinity of the peptide for artificial lipid bilayers is more than 15 times higher in the small oligomeric state (hydrodynamic radius ~ 1...
April 4, 2018: Biochimica et Biophysica Acta
Miriam Kutsch, Semra Ince, Christian Herrmann
The human guanylate-binding proteins (hGBPs) exhibit diverse anti-pathogenic and tumor-related functions which make them key players in the innate immune response. The isoforms hGBP-1 to hGBP-5 form homomeric complexes and localise to specific cellular compartments. Upon heteromeric interactions, hGBPs are able to guide each other to their specific compartments. Thus, homo and heteromeric interactions allow the hGBPs to build a network within the cell which might be important for their diverse biological functions...
April 4, 2018: FEBS Journal
Jayita Patwari, Arka Chatterjee, Samim Sardar, Peter Lemmens, Samir Kumar Pal
Co-sensitization to achieve a broad absorption window is a widely accepted technique in light harvesting nanohybrid synthesis. Protoporphyrin (PPIX) and squaraine (SQ2) are two organic sensitizers absorbing in the visible and NIR wavelength regions of the solar spectrum, respectively. In the present study, we have sensitized zinc oxide (ZnO) nanoparticles using PPIX and SQ2 simultaneously for their potential use in broad-band solar light harvesting in photocatalysis. Förster resonance energy transfer (FRET) from PPIX to SQ2 in close proximity to the ZnO surface has been found to enhance visible light photocatalysis...
April 3, 2018: Physical Chemistry Chemical Physics: PCCP
Jayaprakash Periasamy, Vadiraj Kurdekar, Subbarao Jasti, Mamatha B Nijaguna, Sanjana Boggaram, Manjunath A Hurakadli, Dhruv Raina, Lokavya Meenakshi Kurup, Chetan Chintha, Kavyashree Manjunath, Aneesh Goyal, Gayathri Sadasivam, Kavitha Bharatham, Muralidhara Padigaru, Vijay Potluri, Ashok R Venkitaraman
Intracellular signals triggered by DNA breakage flow through proteins containing BRCT (BRCA1 C-terminal) domains. This family, comprising 23 conserved phosphopeptide-binding modules in man, is inaccessible to small-molecule chemical inhibitors. Here, we develop Bractoppin, a drug-like inhibitor of phosphopeptide recognition by the human BRCA1 tandem (t)BRCT domain, which selectively inhibits substrate binding with nanomolar potency in vitro. Structure-activity exploration suggests that Bractoppin engages BRCA1 tBRCT residues recognizing pSer in the consensus motif, pSer-Pro-Thr-Phe, plus an abutting hydrophobic pocket that is distinct in structurally related BRCT domains, conferring selectivity...
March 9, 2018: Cell Chemical Biology
Christoph Manz, Andrei Yu Kobitski, Ayan Samanta, Andres Jäschke, G Ulrich Nienhaus
RNA (ribonucleic acid) molecules are highly flexible biopolymers fluctuating at physiological temperatures among many different conformations that are represented by minima in a hierarchical conformational free energy landscape. Here we have employed single-molecule FRET (smFRET) to explore the energy landscape of the B. subtilis yitJ SAM-I riboswitch (RS). In this small RNA molecule, specific binding of an S-adenosyl-L-methionine (SAM) ligand in the aptamer domain regulates gene expression by inducing structural changes in another domain, the expression platform, causing transcription termination by the RNA polymerase...
March 28, 2018: Journal of Chemical Physics
Wenwei Zheng, Gül H Zerze, Alessandro Borgia, Jeetain Mittal, Benjamin Schuler, Robert B Best
Förster resonance energy transfer (FRET) is a powerful tool for elucidating both structural and dynamic properties of unfolded or disordered biomolecules, especially in single-molecule experiments. However, the key observables, namely, the mean transfer efficiency and fluorescence lifetimes of the donor and acceptor chromophores, are averaged over a broad distribution of donor-acceptor distances. The inferred average properties of the ensemble therefore depend on the form of the model distribution chosen to describe the distance, as has been widely recognized...
March 28, 2018: Journal of Chemical Physics
Andrea Soranno, Franziska Zosel, Hagen Hofmann
Internal friction is frequently found in protein dynamics. Its molecular origin however is difficult to conceptualize. Even unfolded and intrinsically disordered polypeptide chains exhibit signs of internal friction despite their enormous solvent accessibility. Here, we compare four polymer theories of internal friction with experimental results on the intrinsically disordered protein ACTR (activator of thyroid hormone receptor). Using nanosecond fluorescence correlation spectroscopy combined with single-molecule Förster resonance energy transfer (smFRET), we determine the time scales of the diffusive chain dynamics of ACTR at different solvent viscosities and varying degrees of compaction...
March 28, 2018: Journal of Chemical Physics
Songyuan Qu, Chuanbo Liu, Qiong Liu, Wei Wu, Baoji Du, Jin Wang
A discrepancy has emerged in recent years between single-molecule Förster resonance energy transfer (smFRET) measurements and small angle X-ray scattering (SAXS) or small angle neutron scattering experiments in the study of unfolded or intrinsically disordered proteins in denaturing solutions. Despite significant advances that have been made in identifying various factors which may have contributed to the manifestation of the so-called smFRET-SAXS discrepancy, no consensus has been reached so far on its original source or eventual resolution...
March 28, 2018: Journal of Chemical Physics
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