Phosphorylation-Inducing Chimeric Small Molecules

Small molecules have been classically developed to inhibit enzyme activity; however, new classes of small molecules that endow new functions to enzymes via proximity-mediated effect are emerging. Phosphorylation (native or neo) of any given protein-of-interest can alter its structure and function, and we hypothesized that such modifications can be accomplished by small molecules that bring a kinase in proximity to the protein-of-interest. Herein, we describe phosphorylation-inducing chimeric small molecules (PHICS), which enable two example kinases—AMPK and PKC—to phosphorylate target proteins that are not otherwise substrates for these kinases. PHICS are formed by linking small-molecule binders of the kinase and the target protein, and exhibit several features of a bifunctional molecule, including the hook-effect, turnover, isoform specificity, dose and temporal control of phosphorylation, and activity dependent on proximity (i.e., linker length). Using PHICS, we were able to induce native and neo-phosphorylations of BRD4 by AMPK or PKC. Furthermore, PHICS induced a signaling-relevant phosphorylation of the target protein Bruton’s tyrosine kinase in cells. We envision that PHICS-mediated native or neo-phosphorylations will find utility in basic research and medicine.