Lipase and antibacterial activities of a recombinant protein from the accessory glands of female Phlebotomus papatasi (Diptera: Psychodidae)

The reproductive accessory glands of the adult female have a functional versatility in insects, contributing to reproduction in various ways. The major protein secreted by the accessory glands of female Phlebotomus papatasi (Diptera, Psychodidae) has already been characterised and named PhpaLIP (for P. papatasi lipase) because, in terms of its amino-acid sequence, it is very similar to a wide range of vertebrate lipases. The gene coding for PhpaLIP has now been cloned into a pQE30 vector and expressed in Escherichia coli. When the recombinant PhpaLIP was tested in vitro, it was found to have not only lipase-like activity (when p-nitrophenyl caprylate was used as the substrate) but also specific antibacterial activity against some Gram-positive and Gram-negative bacteria. The possible physiological roles of PhpaLIP in P. papatasi are discussed, in the light of these results.