Towards a comprehensive view of the primary structure of venom proteins from the parasitoid wasp Pimpla hypochondriaca

Venom from the parasitoid wasp Pimpla hypochondriaca has potent in vivo activity against insect haemocytes and disrupts host immune responses. Using hybridisation techniques, and more recently random sequence analysis, we had previously identified cDNAs encoding 10 venom proteins from this wasp and deduced their primary structures. We have now extended the random sequence analysis and discovered a further nine cDNAs encoding proteins with predicted signal sequences. The mature proteins were calculated to have masses of between 4 and 22 kDa. Post-signal sequence residues predicted from the cDNAs matched those derived by Edman degradation from venom proteins separated using gel filtration and reverse phase chromatography, confirming that the cloned cDNAs encode proteins which are secreted into the venom sac. Proteins containing at least six cysteine residues were abundant and seven of these cysteine-rich venom proteins, cvp1-7, were identified. The sequences of some of these proteins were similar, or contained similar cysteine arrangements, to Kunitz type protease inhibitors, pacifastin, the trypsin inhibitor domain protein family, atracotoxin and omega-conotoxin, respectively, which occur in a diverse range of animals including spiders, molluscs, humans and grasshoppers. Two small venom proteins, svp1 and svp2, as well as cvp7 did not have similar sequences to proteins in the GenBank protein database suggesting they may be highly specialised venom components. The random sequencing approach has provided a rapid means of determining the primary structure of the majority of Pimpla hypochondriaca venom proteins.