New “Birtoxin analogs” from Androctonus australis venom

• Published in: Biochemical and biophysical research communications 2005-07, Vol.333 (2), p.524-530
• Main Authors: Martin-Eauclaire, Marie-France, Ceard, Brigitte, Bosmans, Frank, Rosso, Jean-Pierre, Tytgat, Jan, Bougis, Pierre E.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; cDNA; Cells, Cultured; Dose-Response Relationship, Drug; Insects; Membrane Potentials - drug effects; Membrane Potentials - physiology; Mice; Molecular Sequence Data; Oocytes - drug effects; Oocytes - physiology; Rats; Scorpion toxins; Scorpion Venoms - chemistry; Scorpion Venoms - metabolism; Scorpion Venoms - toxicity; Scorpions - metabolism; Sequence Homology, Amino Acid; Species Specificity; Survival Analysis; Synaptosomes - metabolism; Voltage-gated sodium channels; Xenopus laevis
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.05.148

From the venom of the scorpion Androctonus australis, we have isolated a new bioactive polypeptide termed AaBTX-L1. When tested on the insect voltage-gated Na + channel (para) of the fruit fly, this toxin was able to induce a clear shift in activation ( V 1/2), resulting in the opening of the channel at more negative membrane potentials. Furthermore, AaBTX-L1 was totally devoid of toxicity when injected into mice intracerebroventricularly and did not compete with radiolabeled voltage-gated K + and Na + channel toxins in binding experiments on rat brain synaptosomes. Using its N-terminal amino acid sequence to design degenerate primers, several clones were amplified by PCR from the A. australis venom gland cDNA library. As a consequence, seven full oligonucleotide sequences encoding “long-chain” polypeptides with only three disulfide bridges have been cloned for the first time and are described here. Remarkably, they share high similarity with the anti-insect toxin Birtoxin from Parabuthus transvaalicus.