Molecular mechanism of pharmacological activation of BK channels
Molecular mechanism of pharmacological activation of BK channels
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DOI：
10.1073/pnas.1114321109
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发表时间：
2012-02-28
影响因子：
11.1
通讯作者：
Heinemann, Stefan H.
中科院分区：
文献类型：
--
作者：
Gessner, Guido;Cui, Yong-Mei;Heinemann, Stefan H.
大电导电压和钙激活的钾离子通道(Slo1BK)具有多种细胞功能，其失调与多种疾病有关。因此，激活BK通道的药物具有巨大的治疗潜力，但它们的应用受到阻碍，部分原因是其作用模式仍然不清楚。在这里，我们提供了关于脱氢松酸衍生物Cym04如何激活BK通道的机械性见解。作为NS1619类BK开放器的代表，Cym04可逆地左移Slo1 BK通道的半激活电压。使用建立的变构BK门控模型，Cym04效应可以通过电压传感器和离子导通门平衡分别向激活和开放状态移动来模拟。Cym04以剪接变体特异的方式激活BK；它不会发生在使用替代神经元外显子9的Slo1 BK通道中，该外显子编码连接跨膜片段S6和细胞质RCK1结构域的连接物-S6/RCK连接物。此外，Cym04不影响该连接子中两个残基缺失的Slo1 BK通道。突变和基于模型的门控分析表明，BK开放剂，如Cym04和NS1619，但不是马洛毒素，通过与S6/RCK连接子功能相互作用激活BK通道，模仿这个据称的被动弹簧的定点缩短，该弹簧从细胞质的门控环结构传递力量来打开通道的门。
Large-conductance voltage- and Ca2+-activated K+ (Slo1 BK) channels serve numerous cellular functions, and their dysregulation is implicated in various diseases. Drugs activating BK channels therefore bear substantial therapeutic potential, but their deployment has been hindered in part because the mode of action remains obscure. Here we provide mechanistic insight into how the dehydroabietic acid derivative Cym04 activates BK channels. As a representative of NS1619-like BK openers, Cym04 reversibly left-shifts the half-activation voltage of Slo1 BK channels. Using an established allosteric BK gating model, the Cym04 effect can be simulated by a shift of the voltage sensor and the ion conduction gate equilibria toward the activated and open state, respectively. BK activation by Cym04 occurs in a splice variant-specific manner; it does not occur in such Slo1 BK channels using an alternative neuronal exon 9, which codes for the linker connecting the transmembrane segment S6 and the cytosolic RCK1 domain-the S6/RCK linker. In addition, Cym04 does not affect Slo1 BK channels with a two-residue deletion within this linker. Mutagenesis and model-based gating analysis revealed that BK openers, such as Cym04 and NS1619 but not mallotoxin, activate BK channels by functionally interacting with the S6/RCK linker, mimicking site-specific shortening of this purported passive spring, which transmits force from the cytosolic gating ring structure to open the channel's gate.