Influence of a NH2‐terminal extension on the activity of KTX2, a K+ channel blocker purified from Androctonus australis scorpion venom

FEBS Letters

Bougis, Pierre E¹  Feyfant, Eric¹  Rochat, Hervé¹  Martin-Eauclaire, Marie-France¹  Legros, Christian¹  Sampieri, François¹ 

[1] Laboratoire de Biochimie, Ingénierie des Protéines, UMR 6560 du Centre National de la Recherche Scientifique, Institut Fédératif Jean Roche, Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France

关键词: Scorpion toxin;    Potassium channel;    Heterologous expression;    Escherichia coli periplasm;   

DOI  :  10.1016/S0014-5793(97)01177-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A cDNA encoding a short polypeptide blocker of K⁺ channels, kaliotoxin 2 (KTX2), from the venom of the North African scorpion Androctonus australis was expressed in the periplasmic space of Escherichia coli. KTX2 was produced as a fusion protein with the maltose binding protein followed by the recognition site for factor Xa or enterokinase preceding the first amino acid residue of the toxin. The fully refolded recombinant KTX2 (rKTX2) was obtained (0.15–0.30 mg/l of culture) and was indistinguishable from the native toxin according to chemical and biological criteria. An N-extended analogue of KTX2 exhibiting three additional residues was also expressed. This analogue had 1000-fold less affinity for the ¹²⁵I-kaliotoxin binding site on rat brain synaptosomes than KTX2. Conformational models of KTX2 and its mutant were designed by amino acid replacement using the structure of agitoxin 2 from Leiurus quinquestriatus as template, to try to understand the decrease in affinity for the receptor.

【 授权许可】

Unknown