CYTOTOXICITY OF PILOSULIN-1, A PEPTIDE FROM THE VENOM OF THE JUMPER ANT MYRMECIA-PILOSULA

The synthetic peptide pilosulin 1, corresponding to the largest define d allergenic polypeptide found in the venom of the jumper ant Myrmecia pilosula, inhibited the incorporation of [methyl-H-3]thymidine into p roliferating Epstein-Barr transformed (EBV) B-cells. The LD50 was four -fold lower in concentration than melittin, a cytotoxic peptide found in honey bee venom. Loss of cell viability was assessed by flow cytome try by measuring the proportion of cells that fluoresced in the presen ce of the fluorescent dye 7-aminoactinomycin D. Examination of prolife rating EBV B-cells indicated that the cells lost viability within a fe w minutes exposure to pilosulin 1. Partial peptides of pilosulin 1 wer e less efficient in causing loss of cell viability and the results sug gest that the 22 N-terminal residues are critical to the cytotoxic act ivity of pilosulin 1. Normal blood white cells were also labile to pil osulin I. T- and B-lymphocytes, monocytes and natural killer cells, ho wever, were more labile than granulocytes. Analysis of pilosulin I usi ng circular dichroism indicated that, in common with melittin and othe r Hymenoptera venom toxins, it had the potential to adopt an cc-helica l secondary structure. (C) 1998 Elsevier Science B.V, All rights reser ved.