Rudolf Virchow Center and Biocenter, University Würzburg, 97080 Würzburg, Germany.
Int J Mol Sci. 2022 Dec 1;23(23):15071. doi: 10.3390/ijms232315071.
The ability to cope with and adapt to changes in the environment is essential for all organisms. Osmotic pressure is a universal threat when environmental changes result in an imbalance of osmolytes inside and outside the cell which causes a deviation from the normal turgor. Cells have developed a potent system to deal with this stress in the form of mechanosensitive ion channels. Channel opening releases solutes from the cell and relieves the stress immediately. In bacteria, these channels directly sense the increased membrane tension caused by the enhanced turgor levels upon hypoosmotic shock. The mechanosensitive channel of small conductance, MscS, from is one of the most extensively studied examples of mechanically stimulated channels. Different conformational states of this channel were obtained in various detergents and membrane mimetics, highlighting an intimate connection between the channel and its lipidic environment. Associated lipids occupy distinct locations and determine the conformational states of MscS. Not all these features are preserved in the larger MscS-like homologues. Recent structures of homologues from bacteria and plants identify common features and differences. This review discusses the current structural and functional models for MscS opening, as well as the influence of certain membrane characteristics on gating.
生物体适应和应对环境变化的能力至关重要。当环境变化导致细胞内外渗透物失衡，引起正常膨压偏离时，渗透压是普遍存在的威胁。细胞已经发展出一种有效的系统，以机械敏感离子通道的形式来应对这种压力。通道打开会将溶质从细胞中释放出来，并立即缓解压力。在细菌中，这些通道可以直接感知到由于低渗冲击导致的膨压水平升高而引起的细胞膜张力增加。来自 的小电导机械敏感通道（MscS）是研究最为广泛的机械刺激通道之一。在不同的清洁剂和膜类似物中获得了该通道的不同构象状态，突出了通道与其脂质环境之间的密切联系。相关脂质占据特定位置，并决定 MscS 的构象状态。并非所有这些特征都在较大的 MscS 样同源物中保留。来自细菌和植物的同源物的最近结构确定了共同特征和差异。本文综述了 MscS 打开的当前结构和功能模型，以及某些膜特性对门控的影响。
