1.C.38.1.2
Sticholysin I (cytolysin ST1; STII; StiII; FraC) (Alvarez et al., 2009). Pore formation goes through a dimer intermediate and then generates the active octamer. Disrupting the key hydrophobic interaction between V60 and F163 (FraC numbering scheme) in the oligomerization interface of FraC, equinatoxin II (EqtII) and sticholysin II (StII) impairs the pore formation activity (Mesa-Galloso et al. 2016). Sticholysin II-mediated cytotoxicity may involve the activation of regulated intracellular responses that anticipates cell death (Soto et al. 2018). Sticholysins represent a prototype of proteins acting through the formation of protein-lipid toroidal pores. Peptides spanning the N-terminus of sticholysins mimic the permeabilizing activity of the full-length toxins (Mesa-Galloso et al. 2019). Phospholipids integrate into the ring of the toroidal pores, promoting their stabilization. Self-association and folding in the membrane determine the mode of action of peptides from the lytic segment of sticholysins (Ros et al. 2019).