Disulphide bond restrains the C-terminal region of thermostable direct hemolysin during folding to promote oligomerization

摘要: Pore-forming toxins (PFTs) are typically produced as water-soluble monomers, which upon interacting with the target cells assemble into transmembrane oligomeric pores. Vibrio parahaemolyticus thermostable direct hemolysin (TDH) is an atypical PFT that exists tetramer in solution, prior to its membrane-binding. TDH structure highlights a core beta-sandwich domain similar those found eukaryotic actinoporin family of PFTs. However, harbors extended C-terminal region (CTR) not documented actinoporins. This CTR remains tethered through intra-molecular disulphide bond. Part be positioned at inter-protomer interfaces tetramer. Here we show truncation, well mutation compromise tetrameric assembly, and membrane-damaging activity TDH. Our study also reveals intra-protomer bond formation during folding/assembly process restrains mediate participation contact formation, thus facilitating oligomerization. once tetramerization achieved, disruption does affect assembly. Altogether, our provides critical insights regarding regulation oligomerization mechanism has been earlier family.