TAILIEUCHUNG - Báo cáo khoa học: Molecular cloning and functional expression of a gene encoding an antiarrhythmia peptide derived from the scorpion toxin

Froma cDNA library of Chinese scorpionButhus martensii Karsch, full-length cDNAs of 351 nucleotides encoding precursors (named BmKIM) that contain signal peptides of 21 amino acid residues, a mature toxin of 61 residues with four disulfide bridges, and an extra Gly-Lys-Lys tail, were isolated. The genomic sequence of BmKIM was cloned and sequenced; it consisted of two exons disrupted by an intron of 1622 bp, the largest known in scorpion toxin genomes, inserted in the region encoding the signal peptide. The cDNA was expressed inEscherichia coli | Eur. J. Biochem. 269 4468-4475 2002 FEBS 2002 doi Molecular cloning and functional expression of a gene encoding an antiarrhythmia peptide derived from the scorpion toxin Fang Peng1 Xian-Chun Zeng1 Xiao-Hua He1 Jun Pu2 Wen-Xin Li1 Zhi-Hui Zhu2 and Hui Liu1 1 Department of Biotechnology College of Life Sciences Wuhan University China department of Cardiology Tongji Hospital Huazhong University of Science and Technology Wuhan China From a cDNA library of Chinese scorpion Buthus martensii Karsch full-length cDNAs of 351 nucleotides encoding precursors named BmKIM that contain signal peptides of 21 amino acid residues a mature toxin of 61 residues with four disulfide bridges and an extra Gly-Lys-Lys tail were isolated. The genomic sequence of BmKIM was cloned and sequenced it consisted of two exons disrupted by an intron of 1622 bp the largest known in scorpion toxin genomes inserted in the region encoding the signal peptide. The cDNA was expressed in Escherichia coli. The recombinant BmKIM was toxic to both mammal and insects. This is the first report that a toxin with such high sequence homology with an insect-specific depressant toxin group exhibits toxicity to mammals. Using whole cell patch-clamp recording it was discovered that the recombinant BmKIM inhibited the sodium current in rat dorsal root ganglion neurons and ventricular myocytes and protected against aconitine-induced cardiac arrhythmia. Keywords sodium current ventricular myocyte rat dorsal root ganglion BmKIM patch-clamp. Scorpion venom is a rich resource for various bioactive peptides. Accumulated data have demonstrated that scorpion neurotoxins affect the ion permeability of excitable cells by specific interaction with Na K Ca2 or Cl-channels 1-3 . Scorpion toxins that interact with sodium channels are composed of 60-70 amino acid residues which can be divided into a or b mammal neurotoxins and classified as excitatory or depressant insect-selective neurotoxins .

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