Elucidation of the Molecular Basis of Selective Recognition Uncovers the Interaction Site for the Core Domain of Scorpion α-Toxins on Sodium Channels
Elucidation of the Molecular Basis of Selective Recognition Uncovers the Interaction Site for the Core Domain of Scorpion α-Toxins on Sodium Channels
复制标题
DOI：
10.1074/jbc.m111.259507
复制
发表时间：
2011-10-07
影响因子：
4.8
通讯作者：
Gurevitz, Michael
中科院分区：
文献类型：
--
作者：
Gur, Maya;Kahn, Roy;Gurevitz, Michael
电压门控Na+通道上的神经毒素受体位点3被各种通道失活的肽毒素抑制剂识别。尽管对这些毒素的影响进行了广泛的研究，但它们与通道的相互作用模式仍有待在分子水平上描述。为了确定与毒素相互作用的通道成分，我们利用了Lqh α IT和Lqh 2蝎α毒素对昆虫和哺乳动物脑Na+通道的相反偏好。大鼠脑rNa（v）1.2a通道DIV/S1-S2、DIV/S3-S4、DI/S5-SS 1和DI/SS 2-S6外环的构建（对Lqh 2高度敏感）在果蝇DmNa（v）1通道的背景中（对Lqh α IT高度敏感），并且对爪蟾卵母细胞中表达的通道嵌合体的毒素活性的检查揭示了Lqh α IT效应的显著降低，而Lqh 2与rNa（v）1.2a同样有效。进一步取代单个环和特定残基，然后检查Lqh 2和Lqh α IT活性的增加或损失，突出了rNa（v）1.2a的DI/S5-S6（孔模块）和DIV/S3（门控模块）的C末端区域对于Lqh 2作用和选择性的重要性。相比之下，在DIV/S3-S4处Glu-1613对Asp的单一取代将rNa（v）1.2a转化为对Lqh α IT的高灵敏度。比较Lqh 2和突变衍生物在rNa（v）1.2a突变通道处的结合位点的去极化驱动解离表明毒素核心结构域与DIV的门控模块相互作用。这些结果构成了在分子水平上更好地理解蝎子α毒素与电压门控Na+通道相互作用的方式的第一步。
Neurotoxin receptor site-3 at voltage-gated Na+ channels is recognized by various peptide toxin inhibitors of channel inactivation. Despite extensive studies of the effects of these toxins, their mode of interaction with the channel remained to be described at the molecular level. To identify channel constituents that interact with the toxins, we exploited the opposing preferences of Lqh alpha IT and Lqh2 scorpion alpha-toxins for insect and mammalian brain Na+ channels. Construction of the DIV/S1-S2, DIV/S3-S4, DI/S5-SS1, and DI/SS2-S6 external loops of the rat brain rNa(v)1.2a channel (highly sensitive to Lqh2) in the background of the Drosophila DmNa(v)1 channel (highly sensitive to Lqh alpha IT), and examination of toxin activity on the channel chimera expressed in Xenopus oocytes revealed a substantial decrease in Lqh alpha IT effect, whereas Lqh2 was as effective as at rNa(v)1.2a. Further substitutions of individual loops and specific residues followed by examination of gain or loss in Lqh2 and Lqh alpha IT activities highlighted the importance of DI/S5-S6 (pore module) and the C-terminal region of DIV/S3 (gating module) of rNa(v)1.2a for Lqh2 action and selectivity. In contrast, a single substitution of Glu-1613 to Asp at DIV/S3-S4 converted rNa(v)1.2a to high sensitivity toward Lqh alpha IT. Comparison of depolarization-driven dissociation of Lqh2 and mutant derivatives off their binding site at rNa(v)1.2a mutant channels has suggested that the toxin core domain interacts with the gating module of DIV. These results constitute the first step in better understanding of the way scorpion alpha-toxins interact with voltage-gated Na+-channels at the molecular level.