Solution structure of BmKTX, a K+ blocker toxin from the Chinese scorpion Buthus Martensi

✍ Scribed by Jean-Guillaume Renisio; Régine Romi-Lebrun; Eric Blanc; Olivier Bornet; Terumi Nakajima; Hervé Darbon

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 481 KB
• Volume: 38
• Category: Article
• ISSN: 0887-3585
• DOI: 10.1002/(sici)1097-0134(20000101)38:1<70::aid-prot8>3.0.co;2-5

✦ Synopsis

BmKTX is a toxin recently purified from the venom of Buthus Martensi, which belongs to the kaliotoxin family. We have determined its solution structure by use of conventional twodimensional NMR techniques followed by distancegeometry and energy minimization. The calculated structure is composed of a short ␣-helix (residues 14 to 20) connected by a tight turn to a two-stranded antiparallel ␤-sheet (sequences 25-27 and 32-34). The ␤-turn connecting these strands belongs to type I. The N-terminal segment (sequence 1 to 8) runs parallel to the ␤-sheet although it cannot be considered as a third strand. Comparison of the conformation of BmKTX and toxins of the kaliotoxin family clearly demonstrates that they are highly related. Therefore, analysis of the residues belonging to the interacting surface of those toxins allows us to propose a functional map of BmKTX slightly different from the one of KTX and AgTX2, which may explain the variations in affinities of these toxins towards the Kv1.3 channels.