1qk6 | pdb_00001qk6
Solution structure of huwentoxin-I by NMR
Structural highlights
Function[TXH1_HAPSC] Lethal neurotoxin that blocks neuromuscular transmission by binding to the nicotinic acetylcholine receptor. Possess presynaptic activity that affects the release of neurotransmitters from autonomic nerve endings of both cholinergic and adrenergic neuroeffector junctions. Selectively inhibits N-type calcium channel (Cav2.2/CACNA1B) and has only very weak effect on L-type calcium channel (Cav1/CACNA1).[1] [2] Publication Abstract from PubMedThe three-dimensional structure in aqueous solution of native huwentoxin-I, a neurotoxin from the venom of the spider Selenocosmia huwena, has been determined from two-dimensional H NMR data recorded at 500 and 600 MHz. Structural constraints consisting of interproton distances inferred from NOEs and dihedral angles from spin-spin coupling constants were used as input for distance geometry calculation with the program XPLOR 3.1. The best 10 structures have NOE violations < 0.3 A, dihedral violations < 2 degrees, and pairwise root-mean-square differences of 1.08 (+/- 0.20) A over backbone atoms (N, C alpha, C). The molecule adopts a compact structure consisting of a small triple-stranded antiparallel beta-sheet and five beta-turns. A small hydrophobic patch consisting of Phe 6, Trp 28, and Trp 31 is located on one side of the molecule. All six lysine residues are distributed on the molecular surface. The three disulfide bridges are buried within the molecule. The structure contains an "inhibitor cystine knot motif" which is adopted by several other small proteins, such as omega-conotoxin, agatoxin IVA, and gurmarin. Proton nuclear magnetic resonance studies on huwentoxin-I from the venom of the spider Selenocosmia huwena: 2. Three-dimensional structure in solution.,Qu Y, Liang S, Ding J, Liu X, Zhang R, Gu X J Protein Chem. 1997 Aug;16(6):565-74. PMID:9263120[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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