Tracking S4 movement by gating pore currents in the bacterial sodium channel NaChBac.
Tracking S4 movement by gating pore currents in the bacterial sodium channel NaChBac.
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DOI：
10.1085/jgp.201411210
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发表时间：
2014-08
期刊：
影响因子：
--
通讯作者：
Catterall WA
中科院分区：
文献类型：
--
作者：
Gamal El-Din TM;Scheuer T;Catterall WA
通过比较S4门控电荷突变体进行的门控孔电流的动力学和电压依赖性，支持电压传感器功能的滑动螺旋模型，并阐明周期性麻痹综合征的致病机制。电压门控钠通道介导可兴奋细胞中动作电位的起始和传播。电压门控钠通道的跨膜段S4位于门控孔中，在那里它感测膜电位并控制通道门控。单个S4精氨酸门控电荷（R1-R3）被较小的氨基酸取代允许离子电流流过突变门控孔，并且这些门控孔电流在一些骨骼肌周期性麻痹综合征中是致病的。门控孔电流的电压依赖性提供了关于门控电荷的跨膜位置的信息，因为S4响应于膜电位而移动。在这里，我们研究了门控孔电流的同源四聚体细菌钠通道NaChBac的突变体中，其中个别精氨酸门控电荷被半胱氨酸取代。门控孔电流观察到每个突变体通道，但具有不同的电压依赖性。将第一（R1 C）或第二（R2 C）精氨酸突变为半胱氨酸导致在超极化膜电位下的门控孔电流，其中通道处于静息状态，但不在去极化电位下，其中通道被激活。相反，R3 C门控孔在超极化膜电位下关闭，并在通道激活时打开。负调节脉冲显示在最超极化电位下R3 C门控孔的时间依赖性失活。我们的研究结果表明，顺序的电压依赖性的门控孔电流从R1到R3的激活和支持逐步向外移动的取代的半胱氨酸通过门控孔的狭窄部分，在野生型通道中的精氨酸侧链密封。门控孔电流的电压依赖性的这种模式与S4螺旋通过门控孔的滑动运动一致。通过与细菌钠通道电压传感器的高分辨率模型的比较，这些结果揭示了周期性麻痹综合征致病性门控孔电流的结构基础。
Comparison of the kinetics and voltage dependence of gating pore current conducted by S4 gating charge mutants supports the sliding-helix model of voltage sensor function and elucidates the pathogenic mechanisms underlying periodic paralysis syndromes. Voltage-gated sodium channels mediate the initiation and propagation of action potentials in excitable cells. Transmembrane segment S4 of voltage-gated sodium channels resides in a gating pore where it senses the membrane potential and controls channel gating. Substitution of individual S4 arginine gating charges (R1–R3) with smaller amino acids allows ionic currents to flow through the mutant gating pore, and these gating pore currents are pathogenic in some skeletal muscle periodic paralysis syndromes. The voltage dependence of gating pore currents provides information about the transmembrane position of the gating charges as S4 moves in response to membrane potential. Here we studied gating pore current in mutants of the homotetrameric bacterial sodium channel NaChBac in which individual arginine gating charges were replaced by cysteine. Gating pore current was observed for each mutant channel, but with different voltage-dependent properties. Mutating the first (R1C) or second (R2C) arginine to cysteine resulted in gating pore current at hyperpolarized membrane potentials, where the channels are in resting states, but not at depolarized potentials, where the channels are activated. Conversely, the R3C gating pore is closed at hyperpolarized membrane potentials and opens with channel activation. Negative conditioning pulses revealed time-dependent deactivation of the R3C gating pore at the most hyperpolarized potentials. Our results show sequential voltage dependence of activation of gating pore current from R1 to R3 and support stepwise outward movement of the substituted cysteines through the narrow portion of the gating pore that is sealed by the arginine side chains in the wild-type channel. This pattern of voltage dependence of gating pore current is consistent with a sliding movement of the S4 helix through the gating pore. Through comparison with high-resolution models of the voltage sensor of bacterial sodium channels, these results shed light on the structural basis for pathogenic gating pore currents in periodic paralysis syndromes.
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影响因子：
64.8
作者：
Payandeh, Jian;El-Din, Tamer M. Gamal;Scheuer, Todd;Zheng, Ning;Catterall, William A.
通讯作者：
Catterall, William A.
影响因子：
64.8
作者：
Long, Stephen B.;Tao, Xiao;MacKinnon, Roderick
通讯作者：
MacKinnon, Roderick
影响因子：
2.4
作者：
Blanchet, Jonathan;Chahine, Mohamed
通讯作者：
Chahine, Mohamed
DOI：
10.1073/pnas.0806486105
发表时间：
2008-09-30
影响因子：
11.1
作者：
DeCaen, Paul G.;Yarov-Yarovoy, Vladimir;Catterall, William A.
通讯作者：
Catterall, William A.
影响因子：
2.4
作者：
Chahine, M;Pilote, S;Sato, C
通讯作者：
Sato, C