An overview of toxins and genes from the venom of the Asian scorpion Buthus martensi Karsch

Among the different scorpion species, Buthus martensi Karsch (Bm K), a widely distributed scorpion species in Asia, has received a lot of attention. Indeed, over the past decade, more than 70 different peptides, toxins or homologues have been isolated and more peptides are probably still to be revealed. This review is focusing on the many peptides isolated from the venom of this scorpion, their targets, their genes and their structures. The aim is to give both a state of the art' view of the research on Bin K venom and an illustration of the complexity of this scorpion venom. In the present manuscript, we have listed the different ion channel toxins and homologues isolated from the venom of Bm K, either from the literature or from databases. We have described here 51 long-chain peptides related to the Na+ channel toxins family: 34 related to the alpha-toxin family, four related to the excitatory insect toxin family, 10 related to the depressant insect toxin, one beta-like toxin plus two peptides, Bin K AS and AS 1, that act on ryanodine receptors. We also listed 18 peptides related to the K+ channel toxin family: 14 short chain toxins or homologues, two long chain K+ toxin homologues and two putative K+ toxin precursors. Additionally, two chlorotoxin like peptides (Bm-12 and 12b) have been isolated in the venom of Bin K. Besides these ion channels toxins, two peptides without disulfide bridges (the bradykinin-potentiating peptide BmK bpp and BmK nl) and three peptides with no known functions have also been discovered in this venom. We have also taken the opportunity of this review to update the classification of scorpion K+ toxins (Tytgat et al., 1999) which now presents 17 subfamilies instead of the 12 described earlier. The work on the venom of Bm K led to the discovery of two new subfamilies, alpha-KTx14 and alpha-KTx17. (C) 2002 Elsevier Science Ltd. All rights reserved.