Genetically Encoded Activators of Small Molecules for Imaging and Drug Delivery

Abstract

Chemical biologists have developed many tools based on genetically encoded macromolecules and small, synthetic compounds. The two different approaches are extremely useful, but they have inherent limitations. In this Minireview, we highlight examples of strategies that combine both concepts to tackle challenging problems in chemical biology. We discuss applications in imaging, with a focus on super‐resolved techniques, and in probe and drug delivery. We propose future directions in this field, hoping to inspire chemical biologists to develop new combinations of synthetic and genetically encoded probes.

Multifunctional stimuli-responsive chemogenetic platform for conditional multicolor cell-selective labeling

“…In this strategy, the genetically encoded activators (consisting of peptides or proteins) can specifically activate the small synthetic ligands (fluorogens) to a fluorescent state by transient or covalent binding. [5][6][7] Such hybrid approaches combine the excellent targeting-specificity of the genetically encoded protein tags with the superior photophysical properties as well as tunability of the small synthetic ligands, which ensures a great deal of experimental versatility and designability. 6 Accordingly, SNAP-tag, 8,9 HaloTag, 10 PYP-tag, 11,12 fluorogen-activating proteins (FAPs) 13 and Fluorescence-Activating and absorption-Shifting Tag (FAST) [14][15][16] have been developed.…”

“…[5][6][7] Such hybrid approaches combine the excellent targeting-specicity of the genetically encoded protein tags with superior photophysical properties as well as tunability of the small synthetic ligands, which ensures a great deal of experimental versatility and designability. 6 Accordingly, SNAP-tags, 8,9 HaloTags, 10 PYP-tags, 11,12 uorogen-activating proteins (FAPs) 13 and uorescence-activating and absorption-shiing Tags (FASTs) [14][15][16] have been developed.…”

Long‐Term, Single‐Molecule Imaging of Proteins in Live Cells with Photoregulated Fluxional Fluorophores

“…The success of this approach is owed to the high specificity of the reaction that forms a stable, covalently‐linked product [11] . Self‐labeling protein tags like HaloTag allow for combining the advantages of genetically encoded labels with synthetic small fluorophores that can provide wide‐ranging functionality [12] . In this work, we report the development of PFFs compatible with physiological pH and HaloTag labeling (Figure 1E), providing access to unprecedentedly long time‐lapse imaging of specific proteins with single‐molecule resolution.…”

Fluorescent labeling of dicysteine‐tagged peptide for monitoring and optimization of protein bio‐production in bacteria

“…Fluorescent labeling of a specific protein of interest (POI) with genetically encoded fluorescent proteins or fusing the POI to an enzyme tag are widely used approaches in chemical biology to study the expression, localization, and trafficking of the protein in live cells and organisms. 7,8 However, the relatively large size of fused tags can sterically disturb the folding, functions, or even the localization of the POI. 9,10 Alternatively, Tsien and coworkers developed small organic fluorophores, termed FlAsH and ReAsH, that are activated by binding to specific tetracysteine motifs (e.g., CCPGCC).…”