Molecular engineering of conotoxins:: The importance of loop size to α-conotoxin structure and function
Molecular engineering of conotoxins:: The importance of loop size to α-conotoxin structure and function
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DOI：
10.1021/jm800278k
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发表时间：
2008-09-25
影响因子：
7.3
通讯作者：
Alewood, Paul F.
中科院分区：
文献类型：
--
作者：
Jin, Ai-Hua;Daly, Norelle L.;Alewood, Paul F.
α-芋螺毒素是烟碱乙酰胆碱受体（nAChR）的竞争性拮抗剂。目前表征的大多数α-芋螺毒素具有4/7环大小，并且神经元α-芋螺毒素的主要特征包括球状二硫键连接和围绕其四个半胱氨酸残基中的第三个的螺旋结构。在这项研究中，一种新的“分子修剪”的方法进行了定义环的大小，结构和功能的α-芋螺毒素之间的关系。这涉及α-芋螺毒素[A10 L]PnIA [4/7]（α 7 nAChR的强效拮抗剂）中第二环的系统性截短。发现截断的惩罚是构象稳定性降低和对二硫键扰乱的敏感性增加。截短至4/4[A10 L]PnIA保持螺旋性，并且没有显著降低α 7 nAChR的电生理活性，而4/3[AIOL]PnIA丧失α 7 nAChR活性和螺旋性。相比之下，所有截短的类似物失去了类似于100倍的亲和力在AMP，模型蛋白的nAChR的细胞外结构域。对接模拟确定了几个氢键的截断后，提供了一个解释，在α 7 nAChR和AChBP观察到的亲和力降低。
alpha-Conotoxins are competitive antagonists of nicotinic acetylcholine receptors (nAChRs). The majority of currently characterized alpha-conotoxins have a 4/7 loop size, and the major features of neuronal alpha-conotoxins include a globular disulfide connectivity and a helical structure centered around the third of their four cysteine residues. In this study, a novel "molecular pruning" approach was undertaken to define the relationship between loop size, structure, and function of a-conotoxins. This involved the systematic truncation of the second loop in the a-conotoxin [A10L]PnIA [4/7], a potent antagonist of the alpha 7 nAChR. The penalty for truncation was found to be decreased conformational stability and increased susceptibility to disulfide bond scrambling. Truncation down to 4/4[A10L]PnIA maintained helicity and did not significantly reduce electrophysiological activity at alpha 7 nAChRs, whereas 4/3[AIOL]PnIA lost both alpha 7 nAChR activity and helicity. In contrast, all truncated analogues lost similar to 100-fold affinity at the AMP, a model protein for the extracellular domain of the nAChR. Docking simulations identified several hydrogen bonds lost upon truncation that provide an explanation for the reduced affinities observed at the alpha 7 nAChR and AChBP.