1.D.289. The Prymnesin Pore-forming Molecule (PPM) Family
Prymnesins, produced by the haptophyte Prymnesium parvum, are considered responsible for fish kills when this species blooms. Membrane disruptive properties have been ascribed to A-type prymnesins. Currently it is suggested that pore-formation is the underlying cause of cell disruption. The hypothesis that A-, B-, and C-type prymnesins interact with sterols to create pores has been tested (Prause et al. 2024). The hemolytic potency of the prymnesin types reflected their cytotoxic potential, with approximate concentrations reaching 50% hemolysis (HC50) of 4 nM (A-type), 54 nM (C-type), and 600 nM (B-type). Interactions with cholesterol appears to play a partial role in the cytotoxic mechanism of pore-formation. It is suggested that prymnesins initially interact with cholesterol and stabilize pores through a subsequent, still unknown mechanism (Prause et al. 2024).