Protein-fragment complementation assays (PCAs) are widely used for investigating protein interactions. However, the fragments used are structurally compromised and have not been optimized nor thoroughly characterized for accurately assessing these interactions. We took advantage of the small size and bright luminescence of NanoLuc to engineer a new complementation reporter (NanoBiT). By design, the NanoBiT subunits (i.e., 1.3 kDa peptide, 18 kDa polypeptide) weakly associate so that their assembly into a luminescent complex is dictated by the interaction characteristics of the target proteins onto which they are appended. To ascertain their general suitability for measuring interaction affinities and kinetics, we determined that their intrinsic affinity (KD = 190 μM) and association constants (kon = 500 M–1 s–1, koff = 0.2 s–1) are outside of the ranges typical for protein interactions. The accuracy of NanoBiT was verified under defined biochemical conditions using the previously characterized interaction...

http://pubs.acs.org/doi/pdfplus/10.1021/acschembio.5b00753

NanoLuc Complementation Reporter Optimized for Accurate Measurement of Protein Interactions in Cells

Exosomes are cell-derived nanovesicles (50–150 nm), which mediate intercellular communication, and are candidate therapeutic agents. However, inefficiency of exosomal message transfer, such as mRNA, and lack of methods to create designer exosomes have hampered their development into therapeutic interventions. Here, we report a set of EXOsomal transfer into cells (EXOtic) devices that enable efficient, customizable production of designer exosomes in engineered mammalian cells. These genetically encoded devices in exosome producer cells enhance exosome production, specific mRNA packaging, and delivery of the mRNA into the cytosol of target cells, enabling efficient cell-to-cell communication without the need to concentrate exosomes. Further, engineered producer cells implanted in living mice could consistently deliver cargo mRNA to the brain. Therapeutic catalase mRNA delivery by designer exosomes attenuated neurotoxicity and neuroinflammation in in vitro and in vivo models of Parkinson’s disease, indicating the potential usefulness of the EXOtic devices for RNA delivery-based therapeutic applications. Exosomes function as intercellular information transmitters and are candidates for delivery of therapeutic agents. Here the authors present EXOtic, a synthetic biology device for in-situ production of designer exosomes and demonstrate in vivo application in models of Parkinson's disease.

/pdf/designer-exosomes-produced-by-implanted-cells-2pczvd2xe1.pdf

Designer exosomes produced by implanted cells intracerebrally deliver therapeutic cargo for Parkinson's disease treatment.

NanoLuc: A Small Luciferase Is Brightening Up the Field of Bioluminescence.

Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.

Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks.

Dynamic interactions between proteins comprise a key mechanism for temporal control of cellular function and thus hold promise for development of novel drug therapies. It remains technically challenging, however, to quantitatively characterize these interactions within the biologically relevant context of living cells. Although, bioluminescence resonance energy transfer (BRET) has often been used for this purpose, its general applicability has been hindered by limited sensitivity and dynamic range. We have addressed this by combining an extremely bright luciferase (Nanoluc) with a means for tagging intracellular proteins with a long-wavelength fluorophore (HaloTag). The small size (19 kDa), high emission intensity, and relatively narrow spectrum (460 nm peak intensity) make Nanoluc luciferase well suited as an energy donor. By selecting an efficient red-emitting fluorophore (635 nm peak intensity) for attachment onto the HaloTag, an overall spectral separation exceeding 175 nm was achieved. This combinati...

NanoBRET--A Novel BRET Platform for the Analysis of Protein-Protein Interactions.

Bioluminescence methodologies have been extraordinarily useful due to their high sensitivity, broad dynamic range, and operational simplicity. These capabilities have been realized largely through incremental adaptations of native enzymes and substrates, originating from luminous organisms of diverse evolutionary lineages. We engineered both an enzyme and substrate in combination to create a novel bioluminescence system capable of more efficient light emission with superior biochemical and physical characteristics. Using a small luciferase subunit (19 kDa) from the deep sea shrimp Oplophorus gracilirostris, we have improved luminescence expression in mammalian cells ∼2.5 million-fold by merging optimization of protein structure with development of a novel imidazopyrazinone substrate (furimazine). The new luciferase, NanoLuc, produces glow-type luminescence (signal half-life >2 h) with a specific activity ∼150-fold greater than that of either firefly (Photinus pyralis) or Renilla luciferases similarly conf...

http://pubs.acs.org/doi/pdf/10.1021/cb3002478

Engineered luciferase reporter from a deep sea shrimp utilizing a novel imidazopyrazinone substrate.

A method to detect the presence or amount of at least one molecule in a sample which employs a derivative of luciferin or a derivative of a fluorophore is provided.

Luminogenic and fluorogenic compounds and methods to detect molecules or conditions

It has been shown that the coelenterazine analog, coelenterazine-v, is an efficient substrate for a reaction catalyzed by Renilla luciferase. The resulting bioluminescence emission maximum is shifted to a longer wavelength up to 40 nm, which allows the use of some "yellow" Renilla luciferase mutants for in vivo imaging. However, the utility of coelenterazine-v in small-animal imaging has been hampered by its instability in solution and in biological tissues. To overcome this drawback, we ligated coelenterazine-v to Ca(2+)-triggered coelenterazine-binding protein from Renilla muelleri, which apparently functions in the organism for stabilizing and protecting coelenterazine from oxidation. The coelenterazine-v bound within coelenterazine-binding protein has revealed a greater long-term stability at both 4 and 37 °C. In addition, the coelenterazine-binding protein ligated by coelenterazine-v yields twice the total light over free coelenterazine-v as a substrate for the red-shifted R. muelleri luciferase. These findings suggest the possibility for effective application of coelenterazine-v in various in vitro assays.

Coelenterazine-v ligated to Ca2+-triggered coelenterazine-binding protein is a stable and efficient substrate of the red-shifted mutant of Renilla muelleri luciferase

The present invention relates to single and dual reporter luminescence assays utilizing reagents to quench an optical, e.g., an enzyme-mediated luminescence, reaction. In one embodiment of the invention, a reagent is added to an assay which selectively quenches a first enzyme-mediated luminescence reaction without affecting a subsequent distinct enzyme-mediated luminescent reaction(s). An assay kit containing one or more selective quench reagents, and compositions comprising the quench reagent(s), are also provided.

Methods to quench light from optical reactions

The invention provides coelenterazine derivatives which are substrates for a non-luminescent enzyme and a pro-substrate for a luminescent enzyme. The invention also provides a method of using the derivatives.

James Unch

Papers

Engineered luciferase reporter from a deep sea shrimp utilizing a novel imidazopyrazinone substrate.

Luminogenic and fluorogenic compounds and methods to detect molecules or conditions

Coelenterazine-v ligated to Ca2+-triggered coelenterazine-binding protein is a stable and efficient substrate of the red-shifted mutant of Renilla muelleri luciferase

Methods to quench light from optical reactions

Coelenterazine derivatives and methods of using same