title: Solution structure of BmKalphaTx11, a toxin from the venom of the Chinese scorpion Buthus martensii Karsch.
abstract: The solution structure of BmKalphaTx11 presented by this paper is distinctive from any other structures of wide-type scorpion alpha-toxins reported so far, for its trans-9,10 peptide bond conformation is accompanied by 'protruding' topology of the 'NC-domain'. The orientation of the C-tail of BmKalphaTx11 is obviously different from that of classical alpha-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 'five-residue-turn' and then different topology of the 'NC-domain', therefore residues at position 58 are believed to function as structure and bioactivity switch for specificity of scorpion alpha-toxins. The mechanism for stabilizing the geometry of the 'NC-domain' in wide-type scorpion alpha-toxins is also discussed.
authors.affiliation: State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, PR China. zhuj@mail.sioc.ac.cn
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
authors.forename: Xiaotian
authors.initials: X
authors.lastname: Tong
authors.forename: Chunyang
authors.initials: C
authors.lastname: Cao
authors.forename: Gong
authors.initials: G
authors.lastname: Wu
authors.forename: Naixia
authors.initials: N
authors.lastname: Zhang
authors.forename: Houming
authors.initials: H
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010802:Phylogeny; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012604:Scorpion Venoms / Q000737:chemistry* / Q000145:classification
chemical_list: C505415:BmKalphaTx11 protein, Buthus martensii; D012604:Scorpion Venoms