Structure of the scorpion toxin BmBKTtx1 solved from single wavelength anomalous scattering of sulfur
Structure of the scorpion toxin BmBKTtx1 solved from single wavelength anomalous scattering of sulfur
复制标题
DOI：
10.1016/j.jsb.2003.11.012
复制
发表时间：
2004-03-01
影响因子：
3
通讯作者：
Lubkowski, J
中科院分区：
文献类型：
--
作者：
Szyk, A;Lu, WY;Lubkowski, J
这篇报道描述了最近从蝎Buthus martensi Karsch毒液中分离出的K+通道阻断毒素BmBKTx1的晶体结构。这是用x射线晶体学方法解决的蝎子短链K+通道阻断毒素的第二个结构。此外，利用折叠后的BmBKTx1的还原二甲基化诱导其结晶和基于硫原子异常信号的结构溶解使该例子非常独特。BmBKTx1单体由31个氨基酸残基组成，其中6个半胱氨酸通过3个二硫桥连接。这种毒素的晶体属于P2(1)空间群，在不对称单元中存在两个分子。单元胞参数为a = 21.40埃，b = 39.70埃，c = 29.37埃，β = 94.13度。利用传统x射线发生器（λ (Cu,Kalpha) = 1.5478 Angstrom）采集到的1.72埃分辨率的高质量数据集（异常信号），确定了12个半胱氨酸残基贡献的硫原子位置，并对实验阶段进行了改进，从而实现了结构求解。最终模型的结晶学r因子为0.166。几个赖氨酸残基上的甲基可以很容易地模拟成电子密度。Elsevier Inc.出版。
This report describes the crystal structure of the K+ channel-blocking toxin, BmBKTx1, isolated recently from the venom of the scorpion Buthus martensi Karsch. This is only the second structure of the short-chain K+ channel-blocking toxin from scorpion solved by means of X-ray crystallography. Additionally, reductive dimethylation of folded BmBKTx1 employed to induce its crystallization and solution of the structure based on the anomalous signal from the sulfur atoms make this example quite unique. The monomer of BmBKTx1 is formed by 31 amino acid residues, including 6 cysteines connected in 3 disulfide bridges. Crystals of this toxin belong to the space group P2(1) with two molecules present in the asymmetric unit. The unit cell parameters are a = 21.40 Angstrom, b = 39.70 Angstrom, c = 29.37 Angstrom, and beta = 94.13degrees. Based on the high-quality dataset (anomalous signal) collected to the resolution 1.72 Angstrom using the conventional X-radiation generator (lambda(Cu,Kalpha) = 1.5478 Angstrom), the positions of sulfur atoms contributed by 12 cysteine residues have been identified, and subsequent improvement of the experimental phases have allowed structure solution. The final model was refined to the crystallographic R-factor of 0.166. The methyl groups on several lysine residues could be easily modeled into the electron density. Published by Elsevier Inc.