Evidence for a new class of scorpion toxins active against K⁺ channels

Abstract

cDNAs encoding novel long-chain scorpion toxins (64 amino acid residues, including only six cysteines) were isolated from cDNA libraries produced from the venom glands of the scorpions Androctonus australis from Old World and Tityus serrulatus from New World. The encoded peptides were very similar to a recently identified toxin from T. serrulatus, which is active against the voltage-sensitive`delayed-rectifier' potassium channel, but they were completely different from the long-chain and short-chain scorpion toxins already characterised. However, there was some sequence similarity (42%) between these new toxins, Aa TX KL L and Ts TX KL L, and scorpion defensins purified from the hemolymph of Buthidae scorpions Leiurus quinquestriatus and A. australis. Thus, according to a multiple sequence alignment using CLUSTAL, these new toxins seem to be related to the scorpion defensins.z 1998 Federation of European Biochemical Societies.

Tityus Serrulatus Venom 1271‐29‐0

“…Of interest is clone 64 called here cTsTx-Kb (cDNA of TsTx-Kb), whose deduced amino acid sequence (Fig. 3) showed 64% identity with the long chain potassium ion channel blocker BmTxKb2 isolated from the scorpion Buthus martensii (Zhu et al, 1999), approximately 91% with the toxin TsTx-Kb described by Rogowski et al (1994) and its sequence is almost identical to the partial sequence of clones Ts-5 H Cl.14 and Ts-3 H Cl.3 published by Legros et al (1998). However, a deletion of a guanine base at Comparison of amino acid sequence of TbTx5 with TbTx IV-5 and TsTx.…”

“…Finally, no significant similarity was found for some other isolated clones after DNA sequence analysis using GenBanK databases and the Fasta program of Pearson and Lipman (1988). In conclusion, we described the use of ELISA in the Comparison of amino acid sequence of cTsTxKb with BmTxKb2 (a putative potassium ion channel blocker from Buthus martensii, Zhu et al, 1999); TsTx-Kb (potassium ion channel blocker from Titus serrulatus, Rogowski et al, 1994) and clones Ts5 H Cl.14 and Ts3 H Cl.3 (Legros et al, 1998). Numbering corresponding to the signal peptide is negatively numbered.…”

Genomic organization of three novel toxins from the scorpion Buthus martensi Karsch that are active on potassium channels

“…The toxins in the same group share similar amino acid sequences and physiological or pharmacological functions. Though over 40 different scorpion K + channel toxins have been reported [22], there has been little information on their gene structures. Only the genes of KTX from Androctonus australis [14], ChTX from Leiurus quinquestriatus hebraeus [16] and toxin Ts κ from Tityus serrulatus (only the cDNA sequence is available) [15] have been elucidated.…”

Evidence for the Existence of Insect Defensin‐Like Peptide in Scorpion Venom

“…A multiple sequence alignment made by using CLUSTAL revealed that these new toxins are related to the insect defensins. Their precursors contain a prosequence of eight residues (8,13).…”