Abstract: Engineered promiscuous biotin ligases and methods of using them in proximity labeling are described. In particular, the invention provides novel biotin ligase variants having increased promiscuous biotinylation activity capable of proximity labeling of proteins in live cells in as little as 10 minutes.

Abstract: Tobacco etch virus protease (TEV) is one of the most widely used proteases in biotechnology because of its exquisite sequence-specificity. A limitation of TEV is its slow catalytic rate, which limits product generation and therefore signal output. Provided is a generalizable yeast-based platform for directed evolution of protease catalytic properties. Protease activity is determined via proteolytic release of a membrane-anchored transcription factor, and access to TEV's cleavage site is temporally regulated using a photosensory LOV domain. By gradually decreasing light exposure time, faster variants of TEV were selected over multiple rounds of selection. The mutant TEV proteases and the directed evolution platform are useful in a wide range of biotechnology applications, such as FLARE and SPARK tools.

Abstract: Engineered promiscuous biotin ligases and methods of using them in proximity labeling are described. In particular, the invention provides novel biotin ligase variants having increased promiscuous biotinylation activity capable of proximity labeling of proteins in live cells in as little as 10 minutes.

Abstract: The present disclosure provides polypeptides, nucleic acids, polypeptide systems, and nucleic acid systems for detecting protein-protein interactions. The polypeptides, nucleic acids, and systems are useful for detecting protein-protein interactions. The present disclosure also provides such methods.

Abstract: The present disclosure provides a light-activated, calcium-gated polypeptide; and a system comprising: a) the light-activated, calcium-gated polypeptide; and b) a fusion protein comprising a calcium responsive polypeptide and a protease that cleaves a proteolytically cleavable linker present in the light-activated, calcium-gated polypeptide. The present disclosure provides nucleic acids encoding the light-activated, calcium-gated polypeptide or the system, and cells comprising the nucleic acids. The present disclosure provides methods of detecting a change in intracellular calcium ion concentration. The present disclosure provides methods of controlling or modulating an activity of a cell.

Abstract: An imaging method utilizing a split peroxidase is described herein. Imaging methods involve contacting a cell with a split peroxidase and a substrate thereof to allow conversion of a substrate into a product via an enzymatic reaction catalyzed by the reconstitute split peroxidase. Also disclosed herein are split peroxidases, related products and kits.

Abstract: An imaging method comprising expressing in cells a Class I heme peroxidase, which optionally is fused with a protein of interest or a cellular localization signal peptide, and contacting the cells with a substrate of the Class I heme peroxidase to allow conversion of the substrate into a product via an oxidation reaction catalyzed by the Class I heme peroxidase, wherein the product releases a signal detectable by a microscope such as an electron microscope. Also disclosed herein are monomeric mutants of a Class I heme peroxidase and mutants of the enzyme that exhibit elevated enzymatic activity as compared to the corresponding wild-type counterpart.

Abstract: The application discloses methods, materials, and compositions for the labeling of molecules, for example, proteins, in living cells or in subcellular compartments of living cells. In particular, the application relates to proteomic analysis methods; materials and compositions and means based on direct tagging of unknown proteins with tagging enzymes (such as biotin ligase or a peroxidase) within the vicinity of a tagging substrate (such as a tyramide) within living cells, with optional targeting to specific subcellular locations by expression of genetic constructs.

Abstract: The present disclosure provides compositions and methods of use thereof for labeling peptide and proteins in vitro or in vivo. The methods described herein employ lipoic acid ligase or mutants thereof, and lipoic acid analogs (e.g., lipoic acid analogs comprising a resorufin moiety) recognized by lipoic acid ligase and lipoic acid ligase mutants. Also provided herein is a method of imaging protein-protein interaction via a reaction mediated by lipoic acid ligase.

Abstract: An imaging method utilizing a split peroxidase is described herein. Imaging methods involve contacting a cell with a split peroxidase and a substrate thereof to allow conversion of a substrate into a product via an enzymatic reaction catalyzed by the reconstitute split peroxidase. Also disclosed herein are split peroxidases, related products and kits.

Abstract: Compositions (e.g., lipoic acid ligase polypeptides and lipoic acid analogs) and uses thereof in the Probe Incorporation Mediated By Enzymes (PRIME) methods both in vitro and in vivo. Also described herein are kits for performing the PRIME method and vectors/kits for expressing the lipoic acid ligases.

Abstract: An imaging method utilizing a split peroxidase is described herein. Imaging methods involve contacting a cell with a split peroxidase and a substrate thereof to allow conversion of a substrate into a product via an enzymatic reaction catalyzed by the reconstitute split peroxidase. Also disclosed herein are split peroxidases, related products and kits.

Abstract: An imaging method comprising expressing in cells a Class I heme peroxidase, which optionally is fused with a protein of interest or a cellular localization signal peptide, and contacting the cells with a substrate of the Class I heme peroxidase to allow conversion of the substrate into a product via an oxidation reaction catalyzed by the Class I heme peroxidase, wherein the product releases a signal detectable by a microscope such as an electron microscope. Also disclosed herein are monomeric mutants of a Class I heme peroxidase and mutants of the enzyme that exhibit elevated enzymatic activity as compared to the corresponding wild-type counterpart.

Abstract: The invention provides compositions and methods of use thereof for labeling peptide and proteins in vitro or in vivo. The methods described herein employ lipoic acid ligase or mutants thereof, and lipoic acid analogs recognized by lipoic acid ligase and lipoic acid ligase mutants.

Abstract: An imaging method utilizing a split peroxidase is described herein. Imaging methods involve contacting a cell with a split peroxidase and a substrate thereof to allow conversion of a substrate into a product via an enzymatic reaction catalyzed by the reconstitute split peroxidase. Also disclosed herein are split peroxidases, related products and kits.

Abstract: The application discloses methods, materials, and compositions for the labeling of molecules, for example, proteins, in living cells or in subcellular compartments of living cells. In particular, the application relates to proteomic analysis methods; materials and compositions and means based on direct tagging of unknown proteins with tagging enzymes (such as biotin ligase or a peroxidase) within the vicinity of a tagging substrate (such as a tyramide) within living cells, with optional targeting to specific subcellular locations by expression of genetic constructs.

Abstract: The invention provides methods for identifying and optimizing peptide substrates for enzymes such as lipoic acid ligase (Lp1A).

Abstract: The invention relates, in part, to monovalent streptavidin compositions. The invention also relates to methods of preparing and using monovalent streptavidin compositions. In some aspects of the invention, the compositions are monovalent streptavidin with a single femtomolar biotin-binding site.

Abstract: The invention provides compositions and methods of use thereof for labeling peptide and proteins in vitro or in vivo. The methods described herein employ lipoic acid ligase or mutants thereof, and lipoic acid analogs recognized by lipoic acid ligase and lipoic acid ligase mutants.

Abstract: The present disclosure provides compositions and methods of use thereof for labeling peptide and proteins in vitro or in vivo. The methods described herein employ lipoic acid ligase or mutants thereof, and lipoic acid analogs (e.g., lipoic acid analogs comprising a resorufin moiety) recognized by lipoic acid ligase and lipoic acid ligase mutants. Also provided herein is a method of imaging protein-protein interaction via a reaction mediated by lipoic acid ligase.