Fig. 3

Mode of action of tick defensins. A–C Similar to other AMPs, the membrane is the primary target of tick defensins. The three typical models proposed to illustrate membrane permeabilization are presented. In the toroidal-pore model (A), peptides are inserted between the lipid head groups to form a mixed pore. In the carpet model (B), peptides perform as a detergent causing the disruption of bilayer and eventually the formation of micelles. In the barrel-stave model (C), peptides aggregate to shape a bundle in the bilayer with a central lumen, like a barrel comprised of peptides as staves. D Intracellular components with negative charges like nucleic acids and enzymes are suspected to be the second targets of cationic tick defensins