Cytolytic and K+ channel blocking activities of beta-KTx and scorpine-like peptides purified from scorpion venoms
Diego-Garcia, E × Abdel-Mottaleb, Y Schwartz, E. F Rodriguez de la Vega, R. C Tytgat, Jan Possani, L. D #
Cellular and Molecular Life Sciences vol:65 issue:1 pages:187-200
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 beta-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 alpha/beta (CS-alpha beta) 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-alpha beta 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-alpha beta structures.