Ponericins, new antibacterial and insecticidal peptides from the venom of the ant Pachycondyla goeldii

The antimicrobial, insecticidal, and hemolytic properties of peptides isola ted from the venom of the predatory ant Pachycondyla goeldii, a member of t he subfamily Ponerinae, were investigated. Fifteen novel peptides, named po nericins, exhibiting antibacterial and insecticidal properties were purifie d, and their amino acid sequences were characterized. According to their pr imary structure similarities, they can be classified into three families: p onericin G, W, and L, Ponericins share high sequence similarities with know n peptides: ponericins G with cecropin-like peptides, ponericins W with gae gurins and melittin, and ponericins L with dermaseptins, Ten peptides were synthesized for further analysis. Their antimicrobial activities against Gr am-positive and Gram-negative bacteria strains were analyzed together with their insecticidal activities against cricket larvae and their hemolytic ac tivities. Interestingly, within each of the three families, several peptide s present differences in their biological activities. The comparison of the structural features of ponericins with those of well-studied peptides sugg ests that the ponericins may adopt an amphipathic alpha -helical structure in polar environments, such as cell membranes. In the venom, the estimated peptide concentrations appear to be compatible with an antibacterial activi ty in vivo. This suggests that in the ant colony, the peptides exhibit a de fensive role against microbial pathogens arising from prey introduction and /or ingestion.