Wheat germ in vitro translation to produce one of the most toxic sodium channel specific toxins.

Wael Gad (1, 2, 3) , Rahma Ben-Abderrazek (4) , Khadija Wahni (1, 2, 3) , Didier Vertommen (5) , Serge Muyldermans (2, 6) , Balkiss Bouhaouala-Zahar (7, 4) , Joris Messens (1, 2, 3)

1 Brussels Center for Redox Biology, 1050 Brussels, Belgium
2 Structural Biology Research Center, VIB, 1050 Brussels, Belgium
3 SBB - Structural Biology Brussels
4 LR11IPT08 - Laboratoire des Venins et Biomolécules Thérapeutiques - Laboratory of Venoms and Therapeutic Biomolecules
5 de Duve Institute
6 Cellular and Molecular Immunology, Vrije Universiteit Brussel, 1050 Brussels, Belgium
7 UTM - Université de Tunis El Manar

Envenoming following scorpion sting is a common emergency in many parts of the world. During scorpion envenoming, highly toxic small polypeptides of the venom diffuse rapidly within the victim causing serious medical problems. The exploration of toxin structure-function relationship would benefit from the generation of soluble recombinant scorpion toxins in Escherichia coli. We developed an in vitro wheat germ translation system for the expression of the highly toxic Aah (Androctonus australis hector)II protein that requires the proper formation of four disulphide bonds. Soluble, recombinant N-terminal GST (glutathione S-transferase)-tagged AahII toxin is obtained in this in vitro translation system. After proteolytic removal of the GST-tag, purified rAahII (recombinant AahII) toxin, which contains two extra amino acids at its N terminal relative to the native AahII, is highly toxic after i.c.v. (intracerebroventricular) injection in Swiss mice. An LD50 (median lethal dose)-value of 10 ng (or 1.33 pmol), close to that of the native toxin (LD50 of 3 ng) indicates that the wheat germ in vitro translation system produces properly folded and biological active rAahII. In addition, NbAahII10 (Androctonus australis hector nanobody 10), a camel single domain antibody fragment, raised against the native AahII toxin, recognizes its cognate conformational epitope on the recombinant toxin and neutralizes the toxicity of purified rAahII upon injection in mice.

Mots clés: anti-venom; AahII; wheat germ extract; single-domain antibody; scorpion toxin; recombinant protein; dromedary

Domaines: Sciences du Vivant [q-bio]; Toxicologie; Biologie animale; Botanique

Wael Gad, Rahma Ben-Abderrazek, Khadija Wahni, Didier Vertommen, Serge Muyldermans, et al.. Wheat germ in vitro translation to produce one of the most toxic sodium channel specific toxins.. Bioscience Reports, 2014, 34 (4), pp.e00122. ⟨10.1042/BSR20140050⟩. ⟨pasteur-01060215⟩