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The solution structure of BmTx3B, a member of the scorpion toxin subfamily α‐KTx 16
Author(s) -
Wang Yuefeng,
Chen Xiang,
Zhang Naixia,
Wu Gong,
Wu Houming
Publication year - 2004
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20322
Subject(s) - scorpion , subfamily , toxin , scorpion toxin , chemistry , venom , microbiology and biotechnology , biology , genetics , biochemistry , gene
This article reports the solution structure of BmTx3B (α‐KTx16.2), a potassium channel blocker belonging to the subfamily α‐KTx16, purified from the venom of the Chinese scorpion Buthus martensi Karsch. In solution, BmTx3B assumes a typical CSαβ motif, with an α‐helix connected to a triple‐stranded β‐sheet by 3 disulfide bridges, which belongs to the first structural group of short‐chain scorpion toxins. On the other hand, BmTx3B is quite different from other toxins (such as ChTx and AgTx2) of this group in terms of the electrostatic and hydrophobic surface distribution. The functional surface (β‐face) of the molecule is characterized by less basic residues (only 2: Lys28 and Arg35) and extra aromatic residues (Phe1, Phe9, Trp15, and Tyr37). The peptide shows a great preference for the Kca1.1 channel over the Kv channel (about a 10 3 ‐fold difference). The model of BmTx3B/Kca1.1 channel complex generated by docking and dynamic simulation reveals that the stable binding between the BmTx3B and Kca1.1 channel is favored by a number of aromatic π–π stacking interactions. The influences of these structural features on the kinetic behavior of the toxin binding to Kca1.1 channel are also discussed. Proteins 2005. © 2004 Wiley‐Liss, Inc.