Higher-order structure formation using refined monomer structures of lipid raft markers, Stomatin, Prohibitin, Flotillin, and HflK/C-related proteins.

Currently, information on the higher-order structure of Stomatin, Prohibitin, Flotillin, and HflK/C (SPFH)-domain proteins is limited. Briefly, the coordinate information (Refined PH1511.pdb) of the stomatin ortholog, PH1511 monomer, was obtained using the artificial intelligence, ColabFold: AlphaFold2. Thereafter, the 24mer homo-oligomer structure of PH1511 was constructed using the superposing method, with HflK/C and FtsH (KCF complex) as templates. The 9mer-12mer homo-oligomer structures of PH1511 were also constructed using the ab initio docking method, with the GalaxyHomomer server for artificiality elimination. The features and functional validity of the higher-order structures were discussed. The coordinate information (Refined PH1510.pdb) of the membrane protease PH1510 monomer, which specifically cleaves the C-terminal hydrophobic region of PH1511, was obtained. Thereafter, the PH1510 12mer structure was constructed by superposing 12 molecules of the Refined PH1510.pdb monomer onto a 1510-C prism-like 12mer structure formed along the crystallographic threefold helical axis. The 12mer PH1510 (prism) structure revealed the spatial arrangement of membrane-spanning regions between the 1510-N and 1510-C domains within the membrane tube complex. Based on these refined 3D homo-oligomeric structures, the substrate recognition mechanism of the membrane protease was investigated. These refined 3D homo-oligomer structures are provided via PDB files as Supplementary data and can be used for further reference.