title: Solution structure of BmBKTx1, a new BKCa1 channel blocker from the Chinese scorpion Buthus martensi Karsch.
abstract: BmBKTx1 is a 31-amino acid peptide identified from the venom of the Chinese scorpion Buthus martensi Karsch, blocking high-conductance calcium-activated potassium channels. Sequence homology analysis indicates that BmBKTx1 is a new subfamily of short-chain alpha-KTx toxins of the potassium channel, which we term alpha-KTx19. Synthetic BmBKTx1 was prepared by using solid-phase peptide synthesis. Two-dimensional NMR spectroscopy techniques were used to determine the solution structure of BmBKTx1. The results show that the BmBKTx1 forms a typical cysteine-stabilized alpha/beta scaffold adopted by most short-chain scorpion toxins. The structure of BmBKTx1 consists of a two-stranded antiparallel beta-sheet (residues 20-29) and an alpha-helix (residues 5-15). The three-dimensional structure of BmBKTx1 was also compared with those of two function-related scorpion toxins, charybdotoxin (ChTx) and BmTx1, and their structural and functional implications are discussed.
authors.affiliation: Laboratory of Structural Biology, School of Life Science, University of Science and Technology of China, Hefei, Anhui, PRC.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Cai
authors.forename: Chenqi
authors.initials: C
authors.lastname: Xu
authors.forename: Yingqi
authors.initials: Y
authors.lastname: Xu
authors.forename: Wuyuan
authors.initials: W
authors.lastname: Lu
authors.forename: Cheng-wu
authors.initials: CW
authors.lastname: Chi
authors.forename: Yunyu
authors.initials: Y
authors.lastname: Shi
authors.forename: Jihui
authors.initials: J
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors; D017433:Protein Structure, Secondary; D012604:Scorpion Venoms / Q000737:chemistry* / Q000145:classification; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D013237:Stereoisomerism
chemical_list: C047740:Buthus toxin I; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms; D012996:Solutions