Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143.
Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, CA 94143.
Proc Natl Acad Sci U S A. 2022 Mar 1;119(9). doi: 10.1073/pnas.2110936119.
Voltage-gated ion channels confer excitability to biological membranes, initiating and propagating electrical signals across large distances on short timescales. Membrane excitation requires channels that respond to changes in electric field and couple the transmembrane voltage to gating of a central pore. To address the mechanism of this process in a voltage-gated ion channel, we determined structures of the plant two-pore channel 1 at different stages along its activation coordinate. These high-resolution structures of activation intermediates, when compared with the resting-state structure, portray a mechanism in which the voltage-sensing domain undergoes dilation and in-membrane plane rotation about the gating charge-bearing helix, followed by charge translocation across the charge transfer seal. These structures, in concert with patch-clamp electrophysiology, show that residues in the pore mouth sense inhibitory Ca and are allosterically coupled to the voltage sensor. These conformational changes provide insight into the mechanism of voltage-sensor domain activation in which activation occurs vectorially over a series of elementary steps.
电压门控离子通道赋予生物膜兴奋性，在短时间内沿长距离起始和传播电信号。膜激发需要响应电场变化并将跨膜电压耦合到中央孔门控的通道。为了在电压门控离子通道中解决这个过程的机制，我们在其激活坐标的不同阶段确定了植物双孔通道 1 的结构。这些激活中间态的高分辨率结构与静息态结构相比，描绘了一种机制，其中电压感应域经历扩张和跨门控电荷承载螺旋的膜内平面旋转，随后是电荷穿过电荷转移密封的易位。这些结构与膜片钳电生理学一起表明，孔口的残基感知抑制性 Ca 并与电压传感器变构偶联。这些构象变化为电压传感器域激活的机制提供了深入了解，其中激活在一系列基本步骤中呈矢量发生。
