Venom production, venom gland cell fine structure and complementary DNA cloning of a novel cysteine-rich secretory venom protein of the parasitoid wasp Cotesia glomerata (L.) (Hymenoptera: Braconidae)

In host-parasitoid interactions, the venom fluid of a female wasp (Cotesia glomerata) is considered to play a role in regulation of the host immune response to protect her offspring. In this study, we detected a rapid increase in protein content in the female C.glomerata venom reservoir just after eclosion, at which time the venom gland cell exhibited fine structures typical of secretory function. We isolated a protein from the venom, termed C.glomerata venom protein 1 (CgVP1). After N-terminal amino acid sequencing analysis of CgVP1, the complementary DNA (cDNA) encoding this protein was cloned and sequenced. Two cDNAs (CgVP1-a and CgVP1-b) were obtained whose nucleotide sequences differed at two positions, resulting in putative substitutions of amino acid residues at two positions in the mature protein. The following features were indicated by cDNA sequence analysis and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry analysis: (1) CgVP1 consists of 81 amino acid residues, eight of which are cysteine; (2) CgVP1 is preceded by a putative secretory signal consisting of 18 amino acids; (3) the molecular masses of mature CgVP1-a and CgVP1-b are 9316.2 and 9302.0, respectively; (4) the eight cysteines of CgVP1 form four pairs of intramolecular disulfide bonds; and (5) BLAST searching indicated that CgVP1 has no similarity to previously reported proteins.