Characterisation of the peptide and protein content of ant venoms for use as bioinsecticide and antimicrobial leads (#100)
Animal venom peptides are currently being developed as novel drugs and bioinsecticides. Given that ant venoms are used for predation and defence, their venom is a potential source of these peptides. Also, venomous ants are an untapped source of these lead compounds as they remain extremely understudied. Initially, the protein/peptide components of seven different ant species were characterised. 1D and 2D gels of the venoms revealed proteins ranging from <10 kDa to >250 kDa. NanoESI-QTOF-MS/MS analysis confirmed the presence of common venom proteins and many undescribed proteins. C18 reverse-phase (RP) HPLC separation followed by LC-MALDI-TOF MS of the venoms was then undertaken, this revealed considerable heterogeneity in the HPLC and mass profiles of the five venoms. After optimisation of the MALDI matrices, it was found that venoms contained between 144–1032 peptides. Most of these peptides lie between 1–5 kDa. Disulfide-bonded peptides were also identified in all ant venoms (range 2–28) using the reducing MALDI matrix, 1,5-DAN. Insecticidal activity of whole venom was determined using house crickets. Of the four venoms tested thus far, three venoms showed significant paralytic and lethal activity. Bioassay-guided fractionation using cation exchange and RP-HPLC of three venomsis currently being undertaken to identify insecticidal neurotoxins. The antimicrobial activity of venoms and toxins is also presently being investigated using MIC (minimum inhibitory concentration) assays with both gram positive (Staphylococcus aureus) and gram negative bacteria (Escherichia coli) to identify potential anti-microbial agents. In conclusion, these venoms represent a vast and untapped source of potentially novel bioactive drug and insecticide leads.