Mode shift of the voltage sensors in Shaker K+ channels is caused by energetic coupling to the pore domain.
Mode shift of the voltage sensors in Shaker K+ channels is caused by energetic coupling to the pore domain.
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DOI：
10.1085/jgp.201010573
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发表时间：
2011-05
期刊：
影响因子：
--
通讯作者：
Blunck R
中科院分区：
文献类型：
--
作者：
Haddad GA;Blunck R
电压门控离子通道的电压传感器在膜去极化时经历构象变化，导致孔开放。这种构象变化可以测量为门控电流，并且被认为是通过电压传感器和孔（S4-S5接头）之间的共价连接和孔结构域的C末端（S6）的退火转移到孔结构域。在长时间去极化后，电荷运动的电压依赖性转移到更超极化的电位。这种模式转变与C型失活有关，但最近被认为是由电压传感器本身的松弛引起的。在这项研究中，我们确定了S4-S5接头（I384 N）和S6（F484 G）中的两个ShakerIR突变，当突变时，电压传感器运动与孔开放完全解耦。使用这些突变体，我们表明，孔转移能量到电压传感器上，并从电压传感器解偶联孔导致电压传感器被激活在更多的负电位。这种解偶联也消除了在长时间去极化过程中发生的模移，表明孔影响进入模移。使用电压钳荧光法，我们发现，S4的缓慢构象变化以前与模式转换时，解偶联孔消失。这种效应可以通过孔域施加在电压传感器上的机械负荷来解释，并变构地调节其构象。模式转变是由开放状态的稳定引起的，但导致电压传感器的构象变化。
The voltage sensors of voltage-gated ion channels undergo a conformational change upon depolarization of the membrane that leads to pore opening. This conformational change can be measured as gating currents and is thought to be transferred to the pore domain via an annealing of the covalent link between voltage sensor and pore (S4-S5 linker) and the C terminus of the pore domain (S6). Upon prolonged depolarizations, the voltage dependence of the charge movement shifts to more hyperpolarized potentials. This mode shift had been linked to C-type inactivation but has recently been suggested to be caused by a relaxation of the voltage sensor itself. In this study, we identified two ShakerIR mutations in the S4-S5 linker (I384N) and S6 (F484G) that, when mutated, completely uncouple voltage sensor movement from pore opening. Using these mutants, we show that the pore transfers energy onto the voltage sensor and that uncoupling the pore from the voltage sensor leads the voltage sensors to be activated at more negative potentials. This uncoupling also eliminates the mode shift occurring during prolonged depolarizations, indicating that the pore influences entry into the mode shift. Using voltage-clamp fluorometry, we identified that the slow conformational change of the S4 previously correlated with the mode shift disappears when uncoupling the pore. The effects can be explained by a mechanical load that is imposed upon the voltage sensors by the pore domain and allosterically modulates its conformation. Mode shift is caused by the stabilization of the open state but leads to a conformational change in the voltage sensor.
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电荷不中和突变后的振动通道S4段中和不敏感的门控。
影响因子：
3.8
作者：
Bao, HX;Hakeem, A;Henteleff, M;Starkus, JG;Rayner, MD
通讯作者：
Rayner, MD
DOI：
10.1085/jgp.200609638
发表时间：
2006-11
期刊：
The Journal of general physiology
影响因子：
--
作者：
Blunck R;Cordero-Morales JF;Cuello LG;Perozo E;Bezanilla F
通讯作者：
Bezanilla F
影响因子：
3.8
作者：
Holmgren, M;Smith, PL;Yellen, G
通讯作者：
Yellen, G
影响因子：
3.8
作者：
Ledwell, JL;Aldrich, RW
通讯作者：
Aldrich, RW
影响因子：
5.3
作者：
Bruening-Wright, Andrew;Larsson, H. Peter
通讯作者：
Larsson, H. Peter