Precursor nucleotide sequence and genomic organization of BmTXKS1, a new scorpion toxin-like peptide from Buthus martensii Karsch

Abstract

Scorpion venom contains a variety of small peptides, which can modulate Na +, K +, Ca 2+ and Cl − channel conductance in excitable and non-excitable tissues. A novel full-length cDNA encoding a new toxin-like peptide (named BmTXKS1) was isolated from the venom gland cDNA library of Buthus martensii Karsch. The precursor consists of 60 amino acid residues, with a putative signal peptide of 28 residues and an extra residue, and a mature peptide of 31 residues with an amidated C-terminal. BmTXKS1 shared close homology with BmP01 in 5′UTR and the region encoding the putative signal peptide; especially, the positions of six cysteines are highly conserved among BmTXKS1, PbTX1 and P01-type subfamily of scorpion K + channel toxins, suggesting that they all should present a common three-dimensional fold, namely the Cysteine-Stabilized αβ(CSαβ) motif. By PCR amplification of the genomic region encoding BmTXKS1, we have confirmed the identity of our cloned cDNA, and found that BmTXKS1 gene contains an intron, which is completely identical with that of the characterized scorpion K +-channel-ligands in the size, consensus junctions, putative branch point and A+T abundance.