Solution Structure of BmKK4, the First Member of Subfamily -KTx 17 of Scorpion Toxins
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- 作者：Naixia Zhang ; Xiang Chen ; Minghua Li ; Chunyang Cao ; Yuefeng Wang ; Gong Wu ; Guoyuan Hu ; and Houming Wu
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：October 5, 2004
- 年：2004
- 卷：43
- 期：39
- 页码：12469 - 12476
- 全文大小：235K
- 年卷期：v.43,no.39(October 5, 2004)
- ISSN：1520-4995
文摘
BmKK4 is a 30 amino acid peptide purified from the venom of the Chinese scorpion Buthusmartensi Karsch. It has been classified as the first member of scorpion toxin subfamily 
-KTx 17. The3D structure of BmKK4 in solution has been determined by 2D NMR spectroscopy. This toxin adopts acommon /
-motif, but shows a distinctive local conformation. The most novel feature is that the regulararrangements of the side chains of the residues involved in the -sheet of BmKK4 are distorted by aclassic -bulge structure, which involves two residues (Asp18 and Arg19) in the first strand opposite asingle residue (Tyr26) in the second strand. The bulge produces two main changes in the structure of theantiparallel -sheet: (1) It disrupts the normal alteration of the side chain direction; the side chain ofAsp18 turns over to form a salt bridge with that of Arg19. (2) It accentuates the twist of the sheet, andalters the direction of the antiparallel -sheet. The unusual structural feature of the toxin is attributed tothe shorter peptide segment (Leu15-Arg19) between the third and fourth Cys residues and two uniqueresidues (Asp18 and Arg19) at the position preceding the fourth Cys. In addition, the lower affinity of thepeptide for the Kv channel is correlated to the structural features: residue Arg19 instead of a Lys residueat the critical position for binding and the salt bridge formed between residues Arg19 and Asp18.
-KTx 17. The3D structure of BmKK4 in solution has been determined by 2D NMR spectroscopy. This toxin adopts acommon /-motif, but shows a distinctive local conformation. The most novel feature is that the regulararrangements of the side chains of the residues involved in the -sheet of BmKK4 are distorted by aclassic -bulge structure, which involves two residues (Asp18 and Arg19) in the first strand opposite asingle residue (Tyr26) in the second strand. The bulge produces two main changes in the structure of theantiparallel -sheet: (1) It disrupts the normal alteration of the side chain direction; the side chain ofAsp18 turns over to form a salt bridge with that of Arg19. (2) It accentuates the twist of the sheet, andalters the direction of the antiparallel -sheet. The unusual structural feature of the toxin is attributed tothe shorter peptide segment (Leu15-Arg19) between the third and fourth Cys residues and two uniqueresidues (Asp18 and Arg19) at the position preceding the fourth Cys. In addition, the lower affinity of thepeptide for the Kv channel is correlated to the structural features: residue Arg19 instead of a Lys residueat the critical position for binding and the salt bridge formed between residues Arg19 and Asp18.