Selective Activation of TRPC6 Ion Channel by Metallated Type-B Polyprenylated Polycyclic Acylphloroglucinols

The selective modulation of TRPC6 ion channels has emerged as a promising therapeutic approach for treating neuro-degenerative diseases and depression. Here, we present a significant advancement in this field by demonstrating the se-lective activation of TRPC6 using a metallated type-B PPAP, designated as PPAP53. The success of PPAP53 is attributed to the utilization of the 1,3-diketone motif present in PPAPs for metal coordination. The metallated PPAPs exhibit water solubility and equipotent activity compared to hyperforin, which is a natural product and considered the gold standard in the field. Notably, and in sharp contrast to type-A PPAPs, type-B PPAPs possess unique properties such as synthetic ac-cessibility in gram scale, facile derivatization, being thermally stable and stable against photochemical oxidation. Our detailed investigations reveal that PPAP53 selectively binds to the C-terminus of TRPC6. Although cryo electron micros-copy has resolved the majority of the TRPC6 structure, the binding site in the C-terminus remained unresolved. To ad-dress this issue, we employed state-of-the-art artificial intelligence-based protein structure prediction algorithms, includ-ing AlphaFold2, ColabFold, and trRosetta, to predict the missing C-terminus region. Our computational results, validated against experimental data, indicate that PPAP53 binds to the 777LLKL780-region of the C-terminus, thus providing critical insights into the binding mechanism of PPAP53 with TRPC6.