AI-Based Discovery and CryoEM Structural Elucidation of a K Channel Pharmacochaperone.

Pancreatic K channel trafficking defects underlie congenital hyperinsulinism (CHI) cases unresponsive to the K channel opener diazoxide, the mainstay medical therapy for CHI. Current clinically used K channel inhibitors have been shown to act as pharmacochaperones and restore surface expression of trafficking mutants; however, their therapeutic utility for K trafficking impaired CHI is hindered by high-affinity binding, which limits functional recovery of rescued channels. Recent structural studies of K channels employing cryo-electron microscopy (cryoEM) have revealed a promiscuous pocket where several known K pharmacochaperones bind. The structural knowledge provides a framework for discovering K channel pharmacochaperones with desired reversible inhibitory effects to permit functional recovery of rescued channels. Using an AI-based virtual screening technology AtomNet followed by functional validation, we identified a novel compound, termed Aekatperone, which exhibits chaperoning effects on K channel trafficking mutations. Aekatperone reversibly inhibits K channel activity with a half-maximal inhibitory concentration (IC) ~ 9 μM. Mutant channels rescued to the cell surface by Aekatperone showed functional recovery upon washout of the compound. CryoEM structure of K bound to Aekatperone revealed distinct binding features compared to known high affinity inhibitor pharmacochaperones. Our findings unveil a K pharmacochaperone enabling functional recovery of rescued channels as a promising therapeutic for CHI caused by K trafficking defects.