Structural basis underlying the dual gate properties of KcsA
Structural basis underlying the dual gate properties of KcsA
复制标题
DOI：
10.1073/pnas.0911270107
复制
发表时间：
2010-04-06
影响因子：
11.1
通讯作者：
Shimada, Ichio
中科院分区：
文献类型：
--
作者：
Imai, Shunsuke;Osawa, Masanori;Shimada, Ichio
KcsA是原核生物的pH依赖性钾通道。它的激活，细胞内pH值的降低，与其随后的失活相结合，但潜在的机制仍然难以捉摸。在这里，我们研究了构象变化和平衡的KcsA通过使用溶液NMR光谱。控制温度和pH值的KcsA样品产生三个不同的甲基-TROSY和NOESY光谱，对应于休息，激活和失活状态。细胞外信号的pH依赖性受到细胞内H25突变的影响，表明细胞外和细胞内门的耦合构象变化。K+滴定和NOE实验表明，H_2O对K+的置换使其处于失活状态，可能会干扰K+的渗透。这种激活偶联失活的结构基础与其他K通道的C型失活密切相关。
KcsA is a prokaryotic pH-dependent potassium (K) channel. Its activation, by a decrease in the intracellular pH, is coupled with its subsequent inactivation, but the underlying mechanisms remain elusive. Here, we have investigated the conformational changes and equilibrium of KcsA by using solution NMR spectroscopy. Controlling the temperature and pH of KcsA samples produced three distinct methyl-TROSY and NOESY spectra, corresponding to the resting, activated, and inactivated states. The pH-dependence of the signals from the extracellular side was affected by the mutation of H25 on the intracellular side, indicating the coupled conformational changes of the extracellular and intracellular gates. K+ titration and NOE experiments revealed that the inactivated state was obtained by the replacement of K+ with H2O, which may interfere with the K+-permeation. This structural basis of the activation-coupled inactivation is closely related to the C-type inactivation of other K channels.