Inhibitor mediated protein degradation

Abstract

Several drugs cause the degradation of their target proteins. The discovery of compounds with this property has been serendipitous. We have discovered that the tert‐butyl carbamate‐protected arginine (Boc3Arg) moiety is a degron that can be used to construct inhibitors that induce degradation of their target proteins. Boc3Arg‐linked ethacrynic acid and thiobenzofurazan cause the specific degradation of glutathione‐S‐transferase (GST) isozymes in lysates and whole cells. Similarly, the degradation of Escherichia coli dihydrofolate reductase (eDHFR) is induced when treated with trimethoprim (TMP)‐linked Boc3Arg. Importantly, TMP forms a noncovalent complex with eDHFR, so covalent attachment of the Boc3Arg degron is not required for degradation of the target protein. These Boc3Arg‐inhibitors induced degradation of 30–80% of their abundant target proteins within 2–5 hours. The proteasome is required for Boc3Arg‐mediated degradation but the ubiquitin pathways do not appear to be involved. These results demonstrate that the Boc3Arg moiety provides a general strategy for inducing protein degradation that should be useful in therapeutic and conditional protein knockdown applications. This work was supported by NIH GM54403 (LH) and AI075466 (LH).