Pilosulin 5, a novel histamine-releasing peptide of the Australian ant, Myrmecia pilosula (Jack Jumper Ant)

Venom of the Australian ant species Myrmecia pilosula contains a number of allergenic peptides including pilosulins. To obtain novel cDNA clones that encode the pilosulin-related bioactive peptides, mRNA of M. pilosula species complex was subjected to RT-PCR in which the forward primer corresponds to a nucleotide sequence in the leader sequences of pilosulins. We isolated a cDNA clone encoding the novel bioactive peptide pilosulin 5. Tandem mass analysis was entirely consistent with the cDNA derived sequence, and indicated that pilosulin 5 is connected by a single disulfide bridge to create a dimmer peptide of 8546 Da. Synthetic pilosulin 5 peptide caused a significant histamine release in a dose-dependent manner, and the mastoparan homologous region of pilosulin 5 was responsible for the activity.