Fig. 1: Honokiol is predicted to bind the OSCP subunit of ATP synthase.

A Cryo-EM structure of the human ATP synthase complex (PDB ID: 8H9V) is presented during its catalytic state 3b (Lai Y. et al 2023). The subunits α, β, OSCP and b are red, yellow, purple and golden, respectively. B Three-dimensional (3D) structure of OSCP (chain O, residues 23-213) from the human ATP synthase complex is shown in purple. The OSCP α helixes 1-8 (H1-H8) are indicated. The aminoacidic residues of the OSCP subunit interacting with α, β, and b are in red, yellow, and golden, respectively. The two potential binding sites of HK (in green) with the highest binding affinity are shown, as predicted by AutoDock Vina 1.1.2. C The OSCP subunit structure is prepared in Chimera by removing other chains from the ATP synthase complex, non-standard amino acids, and water molecules. The residues are protonated by adding missing hydrogen atoms at pH 7.4. The OSCP residues interacting with IF1 or the ATP synthase subunits α, β, and b are in orange or in red, yellow, and golden, respectively. D, E The OSCP complexes with the two HK poses, at the N-terminal (D) or the C-terminal (E) regions of the subunit, are analyzed using RING v4.0 and used as input to build residue-interaction networks to detect non-covalent inter-chain interactions. HK is in green, its carbon and oxygen atoms (C₁, O₁, and O₂) are labeled. The OSCP aminoacidic residues that are predicted to bind HK and are involved in interactions with other proteins are indicated in orange (IF1) or red, yellow, and golden (α, β, and b ATP synthase subunits), respectively. The OSCP residues in purple indicate none interaction with other proteins.