scholarly journals Efficient switching of mCherry fluorescence using chemical caging

2017 ◽  
Vol 114 (27) ◽  
pp. 7013-7018 ◽  
Author(s):  
Bas M. C. Cloin ◽  
Elke De Zitter ◽  
Desiree Salas ◽  
Vincent Gielen ◽  
Gert E. Folkers ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Functional Characterization ◽  
Fluorescence Emission ◽  
Total Recovery ◽  
X Ray Crystallography ◽  
Chemically Induced ◽  
Wide Range ◽  
Fluorescent State

Fluorophores with dynamic or controllable fluorescence emission have become essential tools for advanced imaging, such as superresolution imaging. These applications have driven the continuing development of photoactivatable or photoconvertible labels, including genetically encoded fluorescent proteins. These new probes work well but require the introduction of new labels that may interfere with the proper functioning of existing constructs and therefore require extensive functional characterization. In this work we show that the widely used red fluorescent protein mCherry can be brought to a purely chemically induced blue-fluorescent state by incubation with β-mercaptoethanol (βME). The molecules can be recovered to the red fluorescent state by washing out the βME or through irradiation with violet light, with up to 80% total recovery. We show that this can be used to perform single-molecule localization microscopy (SMLM) on cells expressing mCherry, which renders this approach applicable to a very wide range of existing constructs. We performed a detailed investigation of the mechanism underlying these dynamics, using X-ray crystallography, NMR spectroscopy, and ab initio quantum-mechanical calculations. We find that the βME-induced fluorescence quenching of mCherry occurs both via the direct addition of βME to the chromophore and through βME-mediated reduction of the chromophore. These results not only offer a strategy to expand SMLM imaging to a broad range of available biological models, but also present unique insights into the chemistry and functioning of a highly important class of fluorophores.

scholarly journals NMR reveals light-induced changes in the dynamics of a photoswitchable fluorescent protein

2019 ◽  
Author(s):  
N. E. Christou ◽  
I. Ayala ◽  
K. Giandoreggio-Barranco ◽  
M. Byrdin ◽  
V. Adam ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Environmental Conditions ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Conformational Dynamics ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dynamic View ◽  
Fluorescent State ◽  
Induced Changes

AbstractThe availability of fluorescent proteins with distinct phototransformation properties is crucial for a wide range of applications in advanced fluorescence microscopy and biotechnology. To rationally design new variants optimized for specific applications, a detailed understanding of the mechanistic features underlying phototransformation is essential. At present, little is known about the conformational dynamics of fluorescent proteins at physiological temperature, and how these dynamics contribute to the observed phototransformation properties. Here, we apply high-resolution NMR spectroscopy in solution combined with in-situ sample illumination at different wavelengths to investigate the conformational dynamics of rsFolder, a GFP-derived protein that can be reversibly switched between a green fluorescent state and a non-fluorescent state. Our results add a dynamic view to the static structures obtained by X-ray crystallography. Including NMR into the analytical toolbox used for fluorescent protein research provides new opportunities for investigating the effect of mutations or changes in the environmental conditions on the conformational dynamics of phototransformable fluorescent proteins, and their correlation with the observed photochemical and photophysical properties.SignificancePhoto-transformable Fluorescent Proteins (PTFPs) are essential tools for super-resolution (SR) microscopy. In practical applications, however, researchers often encounter problems when using PTFPs in a particular cellular context, because the environmental conditions (pH, temperature, redox potential, oxygen level, viscosity, …) affect their brightness, photostability, phototransformation kinetics, etc. Rational fluorescent protein engineering exploits the mechanistic information available from structural studies, mainly X-ray crystallography, in order to design new PTFP variants with improved properties for particular applications. Here we apply NMR spectroscopy in solution to investigate the light-induced changes in conformational dynamics of rsFolder, a reversibly switchable fluorescent protein. The dynamic view offered by NMR highlights protein regions that comprise potentially interesting mutation points for future mutagenesis campaigns.

scholarly journals Single-Molecule Studies on a FRET Biosensor: Lessons from a Comparison of Fluorescent Protein Equipped versus Dye-Labeled Species

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3105 ◽  
Author(s):  
Henning Höfig ◽  
Michele Cerminara ◽  
Ilona Ritter ◽  
Antonie Schöne ◽  
Martina Pohl ◽  
...  
Keyword(s):  
Conformational Change ◽  
Single Molecule ◽  
Fluorescent Dyes ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Strong Increase ◽  
Single Molecule Level ◽  
Labeling Scheme

Bacterial periplasmic binding proteins (PBPs) undergo a pronounced ligand-induced conformational change which can be employed to monitor ligand concentrations. The most common strategy to take advantage of this conformational change for a biosensor design is to use a Förster resonance energy transfer (FRET) signal. This can be achieved by attaching either two fluorescent proteins (FPs) or two organic fluorescent dyes of different colors to the PBPs in order to obtain an optical readout signal which is closely related to the ligand concentration. In this study we compare a FP-equipped and a dye-labeled version of the glucose/galactose binding protein MglB at the single-molecule level. The comparison demonstrates that changes in the FRET signal upon glucose binding are more pronounced for the FP-equipped sensor construct as compared to the dye-labeled analog. Moreover, the FP-equipped sensor showed a strong increase of the FRET signal under crowding conditions whereas the dye-labeled sensor was not influenced by crowding. The choice of a labeling scheme should therefore be made depending on the application of a FRET-based sensor.

scholarly journals tdLanYFP, a yellow, bright, photostable and pH insensitive fluorescent protein for live cell imaging and FRET-based sensing strategies

2021 ◽  
Author(s):  
Y. Bousmah ◽  
H. Valenta ◽  
G. Bertolin ◽  
U. Singh ◽  
V. Nicolas ◽  
...  
Keyword(s):  
Single Molecule ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
Resonance Energy ◽  
Live Cell ◽  
Live Cells

AbstractYellow fluorescent proteins (YFP) are widely used as optical reporters in Förster Resonance Energy Transfer (FRET) based biosensors. Although great improvements have been done, the sensitivity of the biosensors is still limited by the low photostability and the poor fluorescence performances of YFPs at acidic pHs. In fact, today, there is no yellow variant derived from the EYFP with a pK1/2 below ∼5.5. Here, we characterize a new yellow fluorescent protein, tdLanYFP, derived from the tetrameric protein from the cephalochordate B. lanceolatum, LanYFP. With a quantum yield of 0.92 and an extinction coefficient of 133 000 mol−1.L.cm−1, it is, to our knowledge, the brightest dimeric fluorescent protein available, and brighter than most of the monomeric YFPs. Contrasting with EYFP and its derivatives, tdLanYFP has a very high photostability in vitro and preserves this property in live cells. As a consequence, tdLanYFP allows the imaging of cellular structures with sub-diffraction resolution with STED nanoscopy. We also demonstrate that the combination of high brightness and strong photostability is compatible with the use of spectro-microscopies in single molecule regimes. Its very low pK1/2 of 3.9 makes tdLanYFP an excellent tag even at acidic pHs. Finally, we show that tdLanYFP can be a FRET partner either as donor or acceptor in different biosensing modalities. Altogether, these assets make tdLanYFPa very attractive yellow fluorescent protein for long-term or single-molecule live-cell imaging that is also suitable for FRET experiment including at acidic pH.

scholarly journals 1.8 Å bright-state structure of the reversibly switchable fluorescent protein Dronpa guides the generation of fast switching variants

2007 ◽  
Vol 402 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Andre C. Stiel ◽  
Simon Trowitzsch ◽  
Gert Weber ◽  
Martin Andresen ◽  
Christian Eggeling ◽  
...  
Keyword(s):  
Blue Light ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Uv Light ◽  
Structural Features ◽  
Trans Isomerization ◽  
Fluorescent State ◽  
Green Fluorescent ◽  
New Applications ◽  
Key Events

RSFPs (reversibly switchable fluorescent proteins) may be repeatedly converted between a fluorescent and a non-fluorescent state by irradiation and have attracted widespread interest for many new applications. The RSFP Dronpa may be switched with blue light from a fluorescent state into a non-fluorescent state, and back again with UV light. To obtain insight into the underlying molecular mechanism of this switching, we have determined the crystal structure of the fluorescent equilibrium state of Dronpa. Its bicyclic chromophore is formed spontaneously from the Cys62–Tyr63–Gly64 tripeptide. In the fluorescent state, it adopts a slightly non-coplanar cis conformation within the interior of a typical GFP (green fluorescent protein) β-can fold. Dronpa shares some structural features with asFP595, another RSFP whose chromophore has previously been demonstrated to undergo a cis–trans isomerization upon photoswitching. Based on the structural comparison with asFP595, we have generated new Dronpa variants with an up to more than 1000-fold accelerated switching behaviour. The mutations which were introduced at position Val157 or Met159 apparently reduce the steric hindrance for a cis–trans isomerization of the chromophore, thus lowering the energy barrier for the blue light-driven on-to-off transition. The findings reported in the present study support the view that a cis–trans isomerization is one of the key events common to the switching mechanism in RSFPs.

scholarly journals Structural analysis of the bright monomeric yellow-green fluorescent protein mNeonGreen obtained by directed evolution

2016 ◽  
Vol 72 (12) ◽  
pp. 1298-1307 ◽  
Author(s):  
Damien Clavel ◽  
Guillaume Gotthard ◽  
David von Stetten ◽  
Daniele De Sanctis ◽  
Hélène Pasquier ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Directed Evolution ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Yellow Fluorescent Protein ◽  
X Rays ◽  
Visible Absorption ◽  
X Ray ◽  
X Ray Crystallography ◽  
Green Fluorescent

Until recently, genes coding for homologues of the autofluorescent protein GFP had only been identified in marine organisms from the phyla Cnidaria and Arthropoda. New fluorescent-protein genes have now been found in the phylum Chordata, coding for particularly bright oligomeric fluorescent proteins such as the tetrameric yellow fluorescent proteinlanYFP fromBranchiostoma lanceolatum. A successful monomerization attempt led to the development of the bright yellow-green fluorescent protein mNeonGreen. The structures oflanYFP and mNeonGreen have been determined and compared in order to rationalize the directed evolution process leading from a bright, tetrameric to a still bright, monomeric fluorescent protein. An unusual discolouration of crystals of mNeonGreen was observed after X-ray data collection, which was investigated using a combination of X-ray crystallography and UV–visible absorption and Raman spectroscopies, revealing the effects of specific radiation damage in the chromophore cavity. It is shown that X-rays rapidly lead to the protonation of the phenolate O atom of the chromophore and to the loss of its planarity at the methylene bridge.

scholarly journals Optical lock-in detection imaging microscopy for contrast-enhanced imaging in living cells

2008 ◽  
Vol 105 (46) ◽  
pp. 17789-17794 ◽  
Author(s):  
Gerard Marriott ◽  
Shu Mao ◽  
Tomoyo Sakata ◽  
Jing Ran ◽  
David K. Jackson ◽  
...  
Keyword(s):  
Optical Switching ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Optical Switch ◽  
Fluorescence Emission ◽  
Optical Probe ◽  
Living Cells ◽  
Cross Correlation Analysis ◽  
Total Fluorescence ◽  
Lock In

One of the limitations on imaging fluorescent proteins within living cells is that they are usually present in small numbers and need to be detected over a large background. We have developed the means to isolate specific fluorescence signals from background by using lock-in detection of the modulated fluorescence of a class of optical probe termed “optical switches.” This optical lock-in detection (OLID) approach involves modulating the fluorescence emission of the probe through deterministic, optical control of its fluorescent and nonfluorescent states, and subsequently applying a lock-in detection method to isolate the modulated signal of interest from nonmodulated background signals. Cross-correlation analysis provides a measure of correlation between the total fluorescence emission within single pixels of an image detected over several cycles of optical switching and a reference waveform detected within the same image over the same switching cycles. This approach to imaging provides a means to selectively detect the emission from optical switch probes among a larger population of conventional fluorescent probes and is compatible with conventional microscopes. OLID using nitrospirobenzopyran-based probes and the genetically encoded Dronpa fluorescent protein are shown to generate high-contrast images of specific structures and proteins in labeled cells in cultured and explanted neurons and in live Xenopus embryos and zebrafish larvae.

Alteration of fluorescent protein spectroscopic properties upon cryoprotection

2012 ◽  
Vol 68 (11) ◽  
pp. 1578-1583 ◽  
Author(s):  
David von Stetten ◽  
Gaëlle O. Batot ◽  
Marjolaine Noirclerc-Savoye ◽  
Antoine Royant
Keyword(s):  
Ethylene Glycol ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Spectroscopic Properties ◽  
Protein Crystal ◽  
Structural Effects ◽  
Noticeable Effect ◽  
Fluorescence Emission Spectra

Cryoprotection of a protein crystal by addition of small-molecule compounds may sometimes affect the structure of its active site. The spectroscopic and structural effects of the two cryoprotectants glycerol and ethylene glycol on the cyan fluorescent protein Cerulean were investigated. While glycerol had almost no noticeable effect, ethylene glycol was shown to induce a systematic red shift of the UV–vis absorption and fluorescence emission spectra. Additionally, ethylene glycol molecules were shown to enter the core of the protein, with one of them binding in close vicinity to the chromophore, which provides a sound explanation for the observed spectroscopic changes. These results highlight the need to systematically record spectroscopic data on crystals of light-absorbing proteins and reinforce the notion that fluorescent proteins must not been seen as rigid structures.

scholarly journals A photoactivatable green-fluorescent protein from the phylum Ctenophora

2009 ◽  
Vol 277 (1685) ◽  
pp. 1155-1160 ◽  
Author(s):  
Steven H. D. Haddock ◽  
Nadia Mastroianni ◽  
Lynne M. Christianson
Keyword(s):  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Green Fluorescent Proteins ◽  
Optical Probes ◽  
Fluorescent Emission ◽  
The Family ◽  
Fluorescent State ◽  
Green Fluorescent

Genes for the family of green-fluorescent proteins (GFPs) have been found in more than 100 species of animals, with some species containing six or more copies producing a variety of colours. Thus far, however, these species have all been within three phyla: Cnidaria, Arthropoda and Chordata. We have discovered GFP-type fluorescent proteins in the phylum Ctenophora, the comb jellies. The ctenophore proteins share the x YG chromophore motif of all other characterized GFP-type proteins. These proteins exhibit the uncommon property of reversible photoactivation, in which fluorescent emission becomes brighter upon exposure to light, then gradually decays to a non-fluorescent state. In addition to providing potentially useful optical probes with novel properties, finding a fluorescent protein in one of the earliest diverging metazoans adds further support to the possibility that these genes are likely to occur throughout animals.

scholarly journals Influence of nanobody binding on fluorescence emission, mobility and organization of GFP-tagged proteins

2020 ◽  
Author(s):  
Falk Schneider ◽  
Christian Eggeling ◽  
Erdinc Sezgin
Keyword(s):  
Green Fluorescent Protein ◽  
Fluorescence Microscopy ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescence Emission ◽  
Fluorescence Properties ◽  
Great Care ◽  
Target Molecules ◽  
Green Fluorescent

SummaryAdvanced fluorescence microscopy studies require specific and monovalent molecular labelling with bright and photostable fluorophores. This necessity led to the widespread use of fluorescently labelled nanobodies against commonly employed fluorescent proteins. However, very little is known how these nanobodies influence their target molecules. Here, we observed clear changes of the fluorescence properties, mobility and organisation of green fluorescent protein (GFP) tagged proteins after labelling with an anti-GFP nanobody. Intriguingly, we did not observe any co-diffusion of fluorescently-labelled nanobodies with the GFP-labelled proteins. Our results suggest significant binding of the nanobodies to a non-emissive, oligomerized form of the fluorescent proteins, promoting disassembly into more monomeric forms after binding. Our findings show that great care must be taken when using nanobodies for studying dynamic and quantitative protein organisation.

Photoactivated structural dynamics of fluorescent proteins

2012 ◽  
Vol 40 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Dominique Bourgeois ◽  
Aline Regis-Faro ◽  
Virgile Adam
Keyword(s):  
Protein Dynamics ◽  
Structural Dynamics ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Super Resolution ◽  
Simulation Tools ◽  
X Ray Crystallography ◽  
Hybrid Approaches ◽  
Actinic Light ◽  
Green Fluorescent

Proteins of the GFP (green fluorescent protein) family have revolutionized life sciences because they allow the tagging of biological samples in a non-invasive genetically encoded way. ‘Phototransformable’ fluorescent proteins, in particular, have recently attracted widespread interest, as their fluorescence state can be finely tuned by actinic light, a property central to the development of super-resolution microscopy. Beyond microscopy applications, phototransformable fluorescent proteins are also exquisite tools to investigate fundamental protein dynamics. Using light to trigger processes such as photoactivation, photoconversion, photoswitching, blinking and photobleaching allows the exploration of the conformational landscape in multiple directions. In the present paper, we review how structural dynamics of phototransformable fluorescent proteins can be monitored by combining X-ray crystallography, in crystallo optical spectroscopy and simulation tools such as quantum chemistry/molecular mechanics hybrid approaches. Besides their usefulness to rationally engineer better performing fluorescent proteins for nanoscopy and other biotechnological applications, these investigations provide fundamental insights into protein dynamics.

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