The Kindling Fluorescent Protein: A Transient Photoswitchable Marker

Physiology ◽  
2006 ◽  
Vol 21 (3) ◽  
pp. 162-170 ◽  
Author(s):  
J. Nathan Henderson ◽  
S. James Remington
Keyword(s):  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Protein A ◽  
Cellular Imaging ◽  
Continuous Observation ◽  
Protein Markers ◽  
Background Fluorescence ◽  
Direct Tracking

Passive fluorescent protein markers are indispensable for dynamic cellular imaging; however, they are unselective, introduce constant background fluorescence, and require continuous observation. Photoactivatable fluorescent proteins have now been developed whose fluorescence can be switched on and off by illumination, allowing selective and direct tracking of tagged objects without the need for continuous imaging. The “kindling fluorescent protein” is a photoactivatable marker with a novel twist: it turns itself off after a selectable period.

scholarly journals Protistan Grazing Analysis by Flow Cytometry Using Prey Labeled by In Vivo Expression of Fluorescent Proteins

2003 ◽  
Vol 69 (11) ◽  
pp. 6848-6855 ◽  
Author(s):  
Yutao Fu ◽  
Charles O'Kelly ◽  
Michael Sieracki ◽  
Daniel L. Distel
Keyword(s):  
Flow Cytometry ◽  
Prey Species ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Heterotrophic Flagellate ◽  
Broad Host Range ◽  
Bacterial Cells ◽  
Protein Markers ◽  
Significant Difference ◽  
Paraphysomonas Imperforata

ABSTRACT Selective grazing by protists can profoundly influence bacterial community structure, and yet direct, quantitative observation of grazing selectivity has been difficult to achieve. In this investigation, flow cytometry was used to study grazing by the marine heterotrophic flagellate Paraphysomonas imperforata on live bacterial cells genetically modified to express the fluorescent protein markers green fluorescent protein (GFP) and red fluorescent protein (RFP). Broad-host-range plasmids were constructed that express fluorescent proteins in three bacterial prey species, Escherichia coli, Enterobacter aerogenes, and Pseudomonas putida. Micromonas pusilla, an alga with red autofluorescence, was also used as prey. Predator-prey interactions were quantified by using a FACScan flow cytometer and analyzed by using a Perl program described here. Grazing preference of P. imperforata was influenced by prey type, size, and condition. In competitive feeding trials, P. imperforata consumed algal prey at significantly lower rates than FP (fluorescent protein)-labeled bacteria of similar or different size. Within-species size selection was also observed, but only for P. putida, the largest prey species examined; smaller cells of P. putida were grazed preferentially. No significant difference in clearance rate was observed between GFP- and RFP-labeled strains of the same prey species or between wild-type and GFP-labeled strains. In contrast, the common chemical staining method, 5-(4,6-dichloro-triazin-2-yl)-amino fluorescein hydrochloride, depressed clearance rates for bacterial prey compared to unlabeled or RFP-labeled cells.

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

Structural Evidence of Photoisomerization Pathways in Fluorescent Proteins

2019 ◽  
Author(s):  
Jeffrey Chang ◽  
Matthew Romei ◽  
Steven Boxer
Keyword(s):  
Rational Design ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Super Resolution ◽  
Unit Cell Size ◽  
Chlorine Substituent ◽  
Gfp Chromophore ◽  
The One ◽  
Green Fluorescent ◽  
Super Resolution Microscopy

<p>Double-bond photoisomerization in molecules such as the green fluorescent protein (GFP) chromophore can occur either via a volume-demanding one-bond-flip pathway or via a volume-conserving hula-twist pathway. Understanding the factors that determine the pathway of photoisomerization would inform the rational design of photoswitchable GFPs as improved tools for super-resolution microscopy. In this communication, we reveal the photoisomerization pathway of a photoswitchable GFP, rsEGFP2, by solving crystal structures of <i>cis</i> and <i>trans</i> rsEGFP2 containing a monochlorinated chromophore. The position of the chlorine substituent in the <i>trans</i> state breaks the symmetry of the phenolate ring of the chromophore and allows us to distinguish the two pathways. Surprisingly, we find that the pathway depends on the arrangement of protein monomers within the crystal lattice: in a looser packing, the one-bond-flip occurs, whereas in a tighter packing (7% smaller unit cell size), the hula-twist occurs.</p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p> <p> </p>

scholarly journals Split-wrmScarlet and split-sfGFP: Tools for faster, easier fluorescent l abeling of endogenous proteins in Caenorhabditis elegans

Genetics ◽  
2021 ◽  
Author(s):  
Jérôme Goudeau ◽  
Catherine S Sharp ◽  
Jonathan Paw ◽  
Laura Savy ◽  
Manuel D Leonetti ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Labeling ◽  
Large Fragment ◽  
C Elegans ◽  
High Affinity ◽  
Red Fluorescent Proteins ◽  
Invaluable Tool ◽  
Endogenous Proteins ◽  
Fluorescent Tags

Abstract We create and share a new red fluorophore, along with a set of strains, reagents and protocols, to make it faster and easier to label endogenous C. elegans proteins with fluorescent tags. CRISPR-mediated fluorescent labeling of C. elegans proteins is an invaluable tool, but it is much more difficult to insert fluorophore-size DNA segments than it is to make small gene edits. In principle, high-affinity asymmetrically split fluorescent proteins solve this problem in C. elegans: the small fragment can quickly and easily be fused to almost any protein of interest, and can be detected wherever the large fragment is expressed and complemented. However, there is currently only one available strain stably expressing the large fragment of a split fluorescent protein, restricting this solution to a single tissue (the germline) in the highly autofluorescent green channel. No available C. elegans lines express unbound large fragments of split red fluorescent proteins, and even state-of-the-art split red fluorescent proteins are dim compared to the canonical split-sfGFP protein. In this study, we engineer a bright, high-affinity new split red fluorophore, split-wrmScarlet. We generate transgenic C. elegans lines to allow easy single-color labeling in muscle or germline cells and dual-color labeling in somatic cells. We also describe a novel expression strategy for the germline, where traditional expression strategies struggle. We validate these strains by targeting split-wrmScarlet to several genes whose products label distinct organelles, and we provide a protocol for easy, cloning-free CRISPR/Cas9 editing. As the collection of split-FP strains for labeling in different tissues or organelles expands, we will post updates at doi.org/10.5281/zenodo.3993663

scholarly journals Functionalization of Cellulose-Based Hydrogels with Bi-Functional Fusion Proteins Containing Carbohydrate-Binding Modules

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3175
Author(s):  
Mariana Barbosa ◽  
Hélvio Simões ◽  
Duarte Miguel F. Prazeres
Keyword(s):  
Fusion Proteins ◽  
Fluorescent Protein ◽  
Protein A ◽  
Chemical Properties ◽  
Main Idea ◽  
Bioactive Molecules ◽  
Scaffolding Protein ◽  
Carbohydrate Binding ◽  
Biological Interactions ◽  
Carbohydrate Binding Modules

Materials with novel and enhanced functionalities can be obtained by modifying cellulose with a range of biomolecules. This functionalization can deliver tailored cellulose-based materials with enhanced physical and chemical properties and control of biological interactions that match specific applications. One of the foundations for the success of such biomaterials is to efficiently control the capacity to combine relevant biomolecules into cellulose materials in such a way that the desired functionality is attained. In this context, our main goal was to develop bi-functional biomolecular constructs for the precise modification of cellulose hydrogels with bioactive molecules of interest. The main idea was to use biomolecular engineering techniques to generate and purify different recombinant fusions of carbohydrate binding modules (CBMs) with significant biological entities. Specifically, CBM-based fusions were designed to enable the bridging of proteins or oligonucleotides with cellulose hydrogels. The work focused on constructs that combine a family 3 CBM derived from the cellulosomal-scaffolding protein A from Clostridium thermocellum (CBM3) with the following: (i) an N-terminal green fluorescent protein (GFP) domain (GFP-CBM3); (ii) a double Z domain that recognizes IgG antibodies; and (iii) a C-terminal cysteine (CBM3C). The ability of the CBM fusions to bind and/or anchor their counterparts onto the surface of cellulose hydrogels was evaluated with pull-down assays. Capture of GFP-CBM3 by cellulose was first demonstrated qualitatively by fluorescence microscopy. The binding of the fusion proteins, the capture of antibodies (by ZZ-CBM3), and the grafting of an oligonucleotide (to CBM3C) were successfully demonstrated. The bioactive cellulose platform described here enables the precise anchoring of different biomolecules onto cellulose hydrogels and could contribute significatively to the development of advanced medical diagnostic sensors or specialized biomaterials, among others.

Fluorescent protein expression in temperature tolerant and susceptible reef-building corals

2021 ◽  
pp. 1-10
Author(s):  
Exequiel Gabriel S. Dizon ◽  
Jeric P. Da-Anoy ◽  
Melissa S. Roth ◽  
Cecilia Conaco
Keyword(s):  
Spectral Properties ◽  
Coral Species ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Antioxidant Properties ◽  
Variable Expression ◽  
Acropora Digitifera ◽  
Insight Into

Abstract Fluorescent proteins (FPs) are reported to play an important role as photoprotectants and antioxidants in corals subjected to stressful conditions. Identifying the various FP genes expressed and FP gene expression patterns under stress in diverse coral species can provide insight into FP function. In this study, we identified 16 putative FP homologues from the transcriptomes of corals with varying susceptibility to elevated temperature, including Acropora digitifera, Favites colemani, Montipora digitata and Seriatopora caliendrum. Each coral expressed a different complement of FP transcripts, which were predicted to have distinct spectral properties. The most diverse and abundant repertoire of FP transcripts, including at least 6 green FPs, were expressed in the temperature-tolerant coral, F. colemani. In comparison, the other corals expressed fewer FP types. Specific FP transcripts exhibited variable expression profiles in coral fragments subjected to 32 ± 1 °C (treatment) or 28 ± 1 °C (control) for up to 72 h, suggesting that distinct FPs may have different roles. Further studies on the expression of the proteins encoded by these FP transcripts, their fluorescence activity, tissue localization, and possible antioxidant properties, are needed to reveal their contribution to thermal stress tolerance in certain species of corals.

scholarly journals Biogenic fluorescent protein–silk fibroin phosphors for high performing light-emitting diodes

2020 ◽  
Vol 7 (7) ◽  
pp. 1790-1800
Author(s):  
Verónica Fernández-Luna ◽  
Juan P. Fernández-Blázquez ◽  
Miguel A. Monclús ◽  
Francisco Javier Rojo ◽  
Rafael Daza ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Light Emitting Diodes ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Light Emitting ◽  
High Performing ◽  
New Family

This work presents a new family of bio-hybrid light-emitting diodes (Bio-HLEDs) using all-bio color down-converting coatings that combine silk fibroin (SF) as a packaging matrix and fluorescent proteins (FPs) as emitters.

scholarly journals Insulin Stimulates Membrane Fusion and GLUT4 Accumulation in Clathrin Coats on Adipocyte Plasma Membranes

2007 ◽  
Vol 27 (9) ◽  
pp. 3456-3469 ◽  
Author(s):  
Shaohui Huang ◽  
Larry M. Lifshitz ◽  
Christine Jones ◽  
Karl D. Bellve ◽  
Clive Standley ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Insulin Signaling ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Tirf Microscopy ◽  
Adipocyte Plasma Membranes ◽  
Kinetics Of

ABSTRACT Total internal reflection fluorescence (TIRF) microscopy reveals highly mobile structures containing enhanced green fluorescent protein-tagged glucose transporter 4 (GLUT4) within a zone about 100 nm beneath the plasma membrane of 3T3-L1 adipocytes. We developed a computer program (Fusion Assistant) that enables direct analysis of the docking/fusion kinetics of hundreds of exocytic fusion events. Insulin stimulation increases the fusion frequency of exocytic GLUT4 vesicles by ∼4-fold, increasing GLUT4 content in the plasma membrane. Remarkably, insulin signaling modulates the kinetics of the fusion process, decreasing the vesicle tethering/docking duration prior to membrane fusion. In contrast, the kinetics of GLUT4 molecules spreading out in the plasma membrane from exocytic fusion sites is unchanged by insulin. As GLUT4 accumulates in the plasma membrane, it is also immobilized in punctate structures on the cell surface. A previous report suggested these structures are exocytic fusion sites (Lizunov et al., J. Cell Biol. 169:481-489, 2005). However, two-color TIRF microscopy using fluorescent proteins fused to clathrin light chain or GLUT4 reveals these structures are clathrin-coated patches. Taken together, these data show that insulin signaling accelerates the transition from docking of GLUT4-containing vesicles to their fusion with the plasma membrane and promotes GLUT4 accumulation in clathrin-based endocytic structures on the plasma membrane.

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