Recombinant scorpine: a multifunctional antimicrobial peptide with activity against different pathogens

Scorpine is an antimicrobial peptide whose structure resembles a hybrid between a defensin and a cecropin. It exhibits antibacterial activity and inhibits the sporogonic development of parasites responsible for murine malaria. In this communication we report the production of scorpine in a heterelogous system, using a specific vector containing its cloned gene. The recombinantly expressed scorpine (RScp) in ^{Anopheles gambie} cells showed antibacterial activity against ^{Bacillus subtilis} and ^{Klebsiella pneumoniae}, at 5 and 10 μM, respectively. It also produced 98% mortality in sexual stages of ^{Plasmodium berghei} at 15 μM and 100% reduction in ^{Plasmodium falciparum} parasitemia at 5 μM. RScp also inhibited virus dengue-2 replication in C6/36 mosquito cells. In addition, we generated viable and fertile transgenic ^Drosophila that overexpresses and correctly secretes RScp into the insect hemolymph, suggesting that the generation of transgenic mosquitoes resistant to different pathogens may be viable. Received 6 May 2008; received after revision 24 July 2008; accepted 29 July 2008     

Cytolytic and K+ channel blocking activities of β-KTx and scorpine-like peptides purified from scorpion venoms

Among the scorpion venom components whose function are poorly known or even show contrasting pharmacological results are those called “orphan peptides”. The most widely distributed are named β-KTx or scorpine-like peptides. They contain three disulfide bridges with two recognizable domains: a freely moving N-terminal amino acid sequence and a tightly folded C-terminal region with a cysteine-stabilized α/β (CS-αβ) motif. Four such peptides and three cloned genes are reported here. They were assayed for their cytolytic, antimicrobial and K ⁺ channel-blocking activities. Two main characteristics were found: the existence of an unusual structural and functional diversity, whereby the full-length peptide can lyse cells or kill microorganisms, and a C-terminal domain containing the CS-αβ motif that can block K ⁺ channels. Furthermore, sequence analyses and phylogenetic reconstructions are used to discuss the evolution of this type of peptide and to highlight the versatility of the CS-αβ structures. Received 13 August 2007; received after revision 30 October 2007; accepted 2 November 2007