Abstract: By directed evolution, various amino acid substitutions which impart greater brightness to the UnaG fluorescent protein were developed. With certain combinations of mutations, the improved UnaG protein has brightness 100 times greater than the original parent sequence. Bi-molecular fluorescence complementation assays using the improved UnaG variants provide strong signal and high resolution and provide powerful tools for detecting protein-protein interactions (PPIs). PPI detection tools for various important proteins are provided. These assays enable highly efficient screening of putative PPI modulators and the identification, verification, and development of therapeutics that disrupt pathological PPIs.

Abstract: The invention is a novel reporter system for measuring protein-protein interactions. The system uses a pair of functionalized coiled coil subunits that spontaneously form two separate homo-oligomers when expressed in cells. The coiled coil subunits are functionalized with fluorescent proteins and complementary interacting proteins. Upon an activation stimulus which promotes the protein-protein interaction, the interacting proteins drive the formation of multivalent aggregates of the homo-oligomers in phase-shifted droplets. The highly concentrated fluorescent proteins in these structures provide high brightness over background fluorescence and a readily observed, quantitative and dynamic indicator of the protein-protein interaction. The reporters and assay methods are amenable to cells and whole organisms.

Abstract: Provided herein are systems, methods and reagents for determining interactors (proteins or nucleic acids) that interact with a protein of interest. The subject system, methods and reagents advantageously allow for the identification of weak and transient protein-protein interactions. Such subject system, methods and reagents are useful, for example, for the determination of specific protein-interactor interactions that exist in particular diseases. Determination of these differences is useful, for example, in the drug development for the treatment of such diseases.

Abstract: The invention is a novel reporter system for measuring protein-protein interactions. The system uses a pair of functionalized coiled coil subunits that spontaneously form two separate homo-oligomers when expressed in cells. The coiled coil subunits are functionalized with fluorescent proteins and complementary interacting proteins. Upon an activation stimulus which promotes the protein-protein interaction, the interacting proteins drive the formation of multivalent aggregates of the homo-oligomers in phase-shifted droplets. The highly concentrated fluorescent proteins in these structures provide high brightness over background fluorescence and a readily observed, quantitative and dynamic indicator of the protein-protein interaction. The reporters and assay methods are amenable to cells and whole organisms.

Abstract: The invention described herein features infrared fluorescent protease reporters (iProteases) and methods of use thereof. The iProteases can be used in in vivo and in vitro assays to detect protease activity and disease states associated with protease activity. In a still further embodiment, the present invention provides a kit comprising any of the above described polynucleotides. In a further aspect, the present invention provides a method of in vivo optical imaging. In a still further embodiment, the in vivo imaging is performed in a living animal. In a further aspect, the present invention provides a method of detecting protease activity, the method comprising expressing a polypeptide according to any of those described above in a cell.

Abstract: Provided herein are systems, methods and reagents for determining interactors (proteins or nucleic acids) that interact with a protein of interest. The subject system, methods and reagents advantageously allow for the identification of weak and transient protein-protein interactions. Such subject system, methods and reagents are useful, for example, for the determination of specific protein-interactor interactions that exist in particular diseases. Determination of these differences is useful, for example, in the drug development for the treatment of such diseases.

Abstract: The invention described herein features variants related to infrared fluorescent proteins, in particular to mutants of a phytochrome from the bacterium Bradyrhizobium sp. ORS278. The variants show approximately a ten-fold increase in brightness compared to other known infrared fluorescent proteins. The variants are monomeric, allowing them to be used as a protein tag without disrupting the function of the tagged protein of interest.

Abstract: The invention described herein features infrared fluorescent protease reporters (iProteases) and methods of use thereof. The iProteases can be used in in vivo and in vitro assays to detect protease activity and disease states associated with protease activity. In a still further embodiment, the present invention provides a kit comprising any of the above described polynucleotides. In a further aspect, the present invention provides a method of in vivo optical imaging. In a still further embodiment, the in vivo imaging is performed in a living animal. In a further aspect, the present invention provides a method of detecting protease activity, the method comprising expressing a polypeptide according to any of those described above in a cell.

Abstract: The present invention provides miniSOG proteins, polynucleotides, and methods of use. When expressed in a bacterial or mammalian cell, miniSOG proteins spontaneously incorporate flavin mononucleotide and produce fluorescence and singlet oxygen upon excitation. Uses include optical and electron microscope imaging, in vivo imaging, detection and localization of protein-protein interactions, and photoablation.

Abstract: The invention described herein features variants related to infrared fluorescent proteins, in particular to mutants of a phytochrome from the bacterium Bradyrhizobium sp. ORS278. The variants show approximately a ten-fold increase in brightness compared to other known infrared fluorescent proteins. The variants are monomeric, allowing them to be used as a protein tag without disrupting the function of the tagged protein of interest.

Abstract: This invention provides novel truncation mutants of a phytochrome from the bacterium Deinococcus radiodurans. When expressed either in bacteria or mammalian cells, these mutant phytochromes spontaneously incorporate biliverdin, a ubiquitous intermediate in heme catabolism, and become fluorescent in the infrared (IR) region. These phytochromes are the first genetically encoded labels that can be excited by far-red light and fluorescent in the true IR (>700 nm). If these mutants instead incorporate protoporphyrin IX, an intermediate in heme biosynthesis, illumination now generates significant amounts of singlet oxygen. Singlet oxygen is useful because it can be used to kill individual proteins or cells, detect long-range protein-protein interactions, or generate electron-microscopic contrast. The invention also relates to methods of making and using such proteins and protein variants.

Abstract: The present invention provides miniSOG proteins, polynucleotides, and methods of use. When expressed in a bacterial or mammalian cell, miniSOG proteins spontaneously incorporate flavin mononucleotide and produce fluorescence and singlet oxygen upon excitation. Uses include optical and electron microscope imaging, in vivo imaging, detection and localization of protein-protein interactions, and photoablation.

Abstract: This invention provides novel truncation mutants of a phytochrome from the bacterium Deinococcus radiodurans. When expressed either in bacteria or mammalian cells, these mutant phytochromes spontaneously incorporate biliverdin, a ubiquitous intermediate in heme catabolism, and become fluorescent in the infrared (IR) region. These phytochromes are the first genetically encoded labels that can be excited by far-red light and fluoresce in the true IR (>700 nm). If these mutants instead incorporate protoporphyrin IX, an intermediate in heme biosynthesis, illumination now generates significant amounts of singlet oxygen. Singlet oxygen is useful because it can be used to kill individual proteins or cells, detect long-range protein-protein interactions, or generate electron-microscopic contrast. The invention also relates to methods of making and using such proteins and protein variants.