Molecular mechanism of pore formation by Plasmodium Perforin-like Protein 2.

Malaria-causing Plasmodium parasites must pass through several host cell types to complete their life cycle. This cell traversal is facilitated by perforin-like proteins (PLPs), among which PLP2 is essential for erythrocyte rupture by gametocytes. However, the mechanism by which PLP2 forms pores is not yet understood. Here, we combine cryo-electron microscopy and tomography to reveal the structural basis of Plasmodium vivax PLP2-mediated membrane attack. PvPLP2 assembles on lipid bilayers into heterogeneous arc- and ring-shaped pores with variable stoichiometries. Among them, we determine the structure of a 17-subunit pore complex in which the pore-forming MACPF domains form the central β-barrel, while the peripheral Apicomplexan PLP C-terminal β-pleated sheet (APCβ) domains anchor the complex to the membrane surface. A disulfide-stabilized mutant captures an intermediate pre-pore complex prior to membrane insertion, delineating the structural transitions that underpin β-barrel deployment. Functionally, PvPLP2 acts preferentially on the inner leaflet of the erythrocyte membrane, a specificity driven by its affinity for negatively charged lipids. Together, these findings establish the pore-formation pathway for a key Plasmodium virulence factor and provide a structural framework for rational design of transmission-blocking agents that prevent gametocyte egress.