Structural basis for the coupling between activation and inactivation gates in K(+) channels.
Structural basis for the coupling between activation and inactivation gates in K(+) channels.
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激活和失活门控之间的耦合相互作用是K+通道的功能标志。这种耦合已经从离子相互作用效应、半胱氨酸可及性和一个明确的能量耦合残基边界中得到了实验证明。KcsA完全开放构象的结构，以及其他四个部分开放的结构，充分说明了激活-失活门控的结构基础。在这里，我们已经确定了内部束栅上的运动触发选择性滤波器构象变化的机制原理，导致非导电c型失活状态。对一系列KcsA开放结构的分析表明，由于TM2的铰链弯曲和旋转，Phe103的芳香环向孔螺旋上的Thr74和Thr75残基以及邻近亚基上的Ile100残基倾斜。这使得残基W67， E71和D80之间的氢键网络破坏了选择性过滤器的稳定性，促进了其非导电构象的进入。103位突变以尺寸依赖的方式影响门控动力学：小侧链取代F103A和F103C严重损害失活动力学，而较大侧链（F103W）的影响更细微。这表明，内部螺旋束和选择性过滤器之间的变构耦合可能依赖于通过空间接触网络传播的直接机械变形。分子动力学模拟计算的平均相互作用表明，Phe103与周围残基之间具有良好的开态相互作用能。在突变体I470A失活受损的Shaker k通道中也发现了类似的相互作用。我们认为，103位侧链重排机械耦合了KcsA和其他多种K通道的激活和失活。
The coupled interplay between activation and inactivation gating is a functional hallmark of K+ channels. This coupling has been experimentally demonstrated from ion interaction effects, cysteine accessibility and is associated with a well-defined boundary of energetically coupled residues. The structure of KcsA in its fully open conformation, as well as four other partial openings, richly illustrates the structural basis of activation-inactivation gating. Here, we have identified the mechanistic principles by which movements on the inner bundle gate trigger conformational changes at the selectivity filter, leading to the non-conductive C-type inactivated state. Analysis of a series of KcsA open structures suggests that as a consequence of the hinge bending and rotation of TM2, the aromatic ring of Phe103 tilts towards residues Thr74 and Thr75 in the pore helix as well as Ile100 in the neighboring subunit. This allows the network of hydrogen bonds among residues W67, E71, and D80 to destabilize the selectivity filter, facilitating entry to its non-conductive conformation. Mutations at position 103, affect gating kinetics in a size-dependent way: small side chain substitutions F103A and F103C severely impair inactivation kinetics, while larger side chains (F103W) have more subtle effects. This suggests that the allosteric coupling between the inner helical bundle and the selectivity filter might rely on straightforward mechanical deformation propagated through a network of steric contacts. Average interactions calculated from molecular dynamics simulations show favourable open state interaction-energies between Phe103 and surrounding residues. Similar interactions were probed in the Shaker K-channel where inactivation was impaired in the mutant I470A. We propose that side chain rearrangements at position 103 mechanically couple activation and inactivation in KcsA and a variety of other K channels.
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全长KCSA的分子结构：细胞质结构域在离子渗透和激活门口中的作用。
影响因子：
3.8
作者：
Cortes, DM;Cuello, LG;Perozo, E
通讯作者：
Perozo, E
影响因子：
56.9
作者：
Cuello, LG;Cortes, DM;Perozo, E
通讯作者：
Perozo, E
影响因子：
3.4
作者：
Klement, Gran;Nilsson, Johanna;Elinder, Fredrik
通讯作者：
Elinder, Fredrik
DOI：
10.1073/pnas.192367299
发表时间：
2002-09-17
影响因子：
11.1
作者：
Chen, J;Seebohm, G;Sanguinetti, MC
通讯作者：
Sanguinetti, MC
影响因子：
56.9
作者：
Baukrowitz, T;Yellen, G
通讯作者：
Yellen, G