HaloPROTACS: Use of Small Molecule PROTACs to Induce Degradation of HaloTag Fusion Proteins

Small molecule-induced protein degradation is an attractive strategy for the development of chemical probes. One method for inducing targeted protein degradation involves the use of PROTACs, heterobifunctional molecules that can recruit specific E3 ligases to a desired protein of interest. PROTACs have been successfully used to degrade numerous proteins in cells, but the peptidic E3 ligase ligands used in previous PROTACs have hindered their development into more mature chemical probes or therapeutics. We report the design of a novel class of PROTACs that incorporate small molecule VHL ligands to successfully degrade HaloTag7 fusion proteins. These HaloPROTACs will inspire the development of future PROTACs with more drug-like properties. Additionally, these HaloPROTACs are useful chemical genetic tools, due to their ability to chemically knock down widely used HaloTag7 fusion proteins in a general fashion

Identification and Characterization of Von Hippel-Lindau-Recruiting Proteolysis Targeting Chimeras (PROTACs) of TANK-Binding Kinase 1

Proteolysis targeting chimeras (PROTACs) are bifunctional molecules that recruit an E3 ligase to a target protein to facilitate ubiquitination and subsequent degradation of that protein. While the field of targeted degraders is still relatively young, the potential for this modality to become a differentiated and therapeutic reality is strong, such that both academic and pharmaceutical institutions are now entering this interesting area of research. In this article, we describe a broadly applicable process for identifying degrader hits based on the serine/threonine kinase TANK-binding kinase 1 (TBK1) and have generalized the key structural elements associated with degradation activities. Compound <b>3i</b> is a potent hit (TBK1 DC₅₀ = 12 nM, <i>D</i>_max = 96%) with excellent selectivity against a related kinase IKKε, which was further used as a chemical tool to assess TBK1 as a target in mutant K-Ras cancer cells