Solution structure of BmKaTx11, a toxin from the venom of the Chinese scorpion Buthus martensii Karsch

• Published in: Biochemical and biophysical research communications 2010-01, Vol.391 (1), p.627-633
• Main Authors: Zhu, Jing, Tong, Xiaotian, Cao, Chunyang, Wu, Gong, Zhang, Naixia, Wu, Houming
• Format: Article
• Language: English
• Subjects: Buthus martensii
• ISSN: 0006-291X
• DOI: 10.1016/j.bbrc.2009.11.110

The solution structure of BmKaTx11 presented by this paper is distinctive from any other structures of wide-type scorpion a-toxins reported so far, for its trans-9,10 peptide bond conformation is accompanied by a~protruding' topology of the a~NC-domain'. The orientation of the C-tail of BmKaTx11 is obviously different from that of classical a-toxins (e.g., AaH2, BmK-M8), despite the fact that they share common trans conformation of peptide bond between residues 9 and 10. Accordingly, there must be other structural factors dominating the orientation of the C-tail except the conformation of peptide bond 9-10. Our study reveals that residues at position 58 play an important role in it, and different type of residues at this position (e.g., Lys, Arg, Met, Ile) result in different spatial relationship between the C-terminus and the a~five-residue-turn' and then different topology of the a~NC-domain', therefore residues at position 58 are believed to function as structure and bioactivity switch for specificity of scorpion a-toxins. The mechanism for stabilizing the geometry of the a~NC-domain' in wide-type scorpion a-toxins is also discussed.