An extracellular Cu2+ binding site in the voltage sensor of BK and Shaker potassium channels.
An extracellular Cu2+ binding site in the voltage sensor of BK and Shaker potassium channels.
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DOI：
10.1085/jgp.200809980
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发表时间：
2008-05
期刊：
影响因子：
--
通讯作者：
Horrigan FT
中科院分区：
文献类型：
--
作者：
Ma Z;Wong KY;Horrigan FT
铜是一种必需的微量元素，可以作为神经系统中的信号分子。在这里，我们证明细胞外 Cu2+ 是 BK 和 Shaker K+ 通道的有效抑制剂。在低微摩尔浓度下，Cu2+ 快速可逆地降低通过膜去极化从 mSlo1 BK 通道引起的宏观 K+ 电导 (GK)。 GK 以剂量依赖性方式降低，IC50 和 Hill 系数分别为 ∼2 μM 和 1.0。饱和 100 μM Cu2+ 会使 GK-V 关系移动 +74 mV，并将 GKmax 降低 27%，而不会影响单通道电导。然而，在膜去极化过程中使用 100 μM Cu2+ 无法抑制 GK，这表明 Cu2+ 与激活的通道相互作用较差。在测试的其他过渡金属离子中，只有 Zn2+ 和 Cd2+ 在 100 μM 时具有显着影响，IC50 > 0.5 mM，表明结合位点具有 Cu2+ 选择性。外部 Cys 或 His 残基的突变不会改变 Cu2+ 敏感性。然而，基于这些位置的取代改变 Cu2+ 和/或 Cd2+ 敏感性的能力，在 mSlo1 电压传感器的跨膜片段 S1、S2 和 S4 中鉴定出了四个假定的 Cu2+ 配位残基（D133、Q151、D153 和 R207）。与结合位点中酸性残基的存在一致，Cu2+敏感性在低细胞外pH值下降低。 S1、S2 和 S4 中的三个带电位置在电压门控通道中高度保守，可以在金属敏感性中发挥普遍作用。我们证明，Shaker 与 mSlo1 一样，对 Cu2+ 比 Zn2+ 更敏感，并且通过突变 S1 或 S4 中的保守位置或降低 pH 值可以改变对这些金属的敏感性。我们的结果表明，电压传感器形成一个状态和 pH 依赖性、金属选择性结合袋，该结合袋可能被生理相关浓度的 Cu2+ 占据，从而抑制 BK 和其他通道的激活。
Copper is an essential trace element that may serve as a signaling molecule in the nervous system. Here we show that extracellular Cu2+ is a potent inhibitor of BK and Shaker K+ channels. At low micromolar concentrations, Cu2+ rapidly and reversibly reduces macrosocopic K+ conductance (GK) evoked from mSlo1 BK channels by membrane depolarization. GK is reduced in a dose-dependent manner with an IC50 and Hill coefficient of ∼2 μM and 1.0, respectively. Saturating 100 μM Cu2+ shifts the GK-V relation by +74 mV and reduces GKmax by 27% without affecting single channel conductance. However, 100 μM Cu2+ fails to inhibit GK when applied during membrane depolarization, suggesting that Cu2+ interacts poorly with the activated channel. Of other transition metal ions tested, only Zn2+ and Cd2+ had significant effects at 100 μM with IC50s > 0.5 mM, suggesting the binding site is Cu2+ selective. Mutation of external Cys or His residues did not alter Cu2+ sensitivity. However, four putative Cu2+-coordinating residues were identified (D133, Q151, D153, and R207) in transmembrane segments S1, S2, and S4 of the mSlo1 voltage sensor, based on the ability of substitutions at these positions to alter Cu2+ and/or Cd2+ sensitivity. Consistent with the presence of acidic residues in the binding site, Cu2+ sensitivity was reduced at low extracellular pH. The three charged positions in S1, S2, and S4 are highly conserved among voltage-gated channels and could play a general role in metal sensitivity. We demonstrate that Shaker, like mSlo1, is much more sensitive to Cu2+ than Zn2+ and that sensitivity to these metals is altered by mutating the conserved positions in S1 or S4 or reducing pH. Our results suggest that the voltage sensor forms a state- and pH-dependent, metal-selective binding pocket that may be occupied by Cu2+ at physiologically relevant concentrations to inhibit activation of BK and other channels.
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影响因子：
3.8
作者：
Diaz, F;Wallner, M;Stefani, E;Toro, L;Latorre, R
通讯作者：
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影响因子：
2.9
作者：
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通讯作者：
Aldrich, RW
DOI：
10.1016/s0969-2126(99)80056-2
发表时间：
1999-04-15
期刊：
STRUCTURE WITH FOLDING & DESIGN
影响因子：
--
作者：
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通讯作者：
Baker, EN
影响因子：
2.9
作者：
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通讯作者：
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影响因子：
2.4
作者：
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通讯作者：
Magistretti, J