Hydration properties of mechanosensitive channel pores define the energetics of gating
Hydration properties of mechanosensitive channel pores define the energetics of gating
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DOI：
10.1088/0953-8984/22/45/454120
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发表时间：
2010-11-17
影响因子：
2.7
通讯作者：
Sukharev, S.
中科院分区：
文献类型：
--
作者：
Anishkin, A.;Akitake, B.;Sukharev, S.
通过周围膜的张力直接打开离子通道似乎是最古老和最简单的门控机制。细菌机械敏感通道MscL和MscS是研究得最好的张力门控纳米孔，但定义其门控的关键物理因素仍存在激烈争论。在这里，我们提出的估计，模拟和实验结果表明，孔的水合作用可能是定义的热力学和动力学的机械敏感通道门控的主要参数之一。我们将通道孔的关闭与疏水门的完全脱水（由“气锁”闭塞）和收缩上方和下方两个水蒸气界面的形成相关联。打开路径是这些界面的扩张，最终导致疏水孔的润湿，这似乎不是闭合路径的确切反向，从而产生滞后。我们具体讨论的作用，极性基团（甘氨酸）埋在狭窄的封闭构象，但暴露在开放状态，改变润湿特性的孔衬里和稳定的导电状态的通道。
Opening of ion channels directly by tension in the surrounding membrane appears to be the most ancient and simple mechanism of gating. Bacterial mechanosensitive channels MscL and MscS are the best-studied tension-gated nanopores, yet the key physical factors that define their gating are still hotly debated. Here we present estimations, simulations and experimental results showing that hydration of the pore might be one of the major parameters defining the thermodynamics and kinetics of mechanosensitive channel gating. We associate closing of channel pores with complete dehydration of the hydrophobic gate (occlusion by 'vapor lock') and formation of two water-vapor interfaces above and below the constriction. The opening path is the expansion of these interfaces, ultimately leading to wetting of the hydrophobic pore, which does not appear to be the exact reverse of the closing path, thus producing hysteresis. We discuss specifically the role of polar groups (glycines) buried in narrow closed conformations but exposed in the open states that change the wetting characteristics of the pore lining and stabilize conductive states of the channels.