School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley WA, Australia.
J Gen Physiol. 2010 Oct;136(4):483-94. doi: 10.1085/jgp.200910376.
Mechanosensitive channels act as molecular transducers of mechanical force exerted on the membrane of living cells by opening in response to membrane bilayer deformations occurring in physiological processes such as touch, hearing, blood pressure regulation, and osmoregulation. Here, we determine the likely structure of the open state of the mechanosensitive channel of large conductance using a combination of patch clamp, fluorescence resonance energy transfer (FRET) spectroscopy, data from previous electron paramagnetic resonance experiments, and molecular and Brownian dynamics simulations. We show that structural rearrangements of the protein can be measured in similar conditions as patch clamp recordings while controlling the state of the pore in its natural lipid environment by modifying the lateral pressure distribution via the lipid bilayer. Transition to the open state is less dramatic than previously proposed, while the N terminus remains anchored at the surface of the membrane where it can either guide the tilt of or directly translate membrane tension to the conformation of the pore-lining helix. Combining FRET data obtained in physiological conditions with simulations is likely to be of great value for studying conformational changes in a range of multimeric membrane proteins.
机械敏感通道作为细胞膜上的分子转换器，对细胞膜上的机械力做出反应，这些机械力是由生理过程中发生的细胞膜双层变形引起的，例如触摸、听觉、血压调节和渗透调节。在这里，我们使用膜片钳、荧光共振能量转移（FRET）光谱学、先前电子顺磁共振实验的数据以及分子和布朗动力学模拟的组合，确定了大电导机械敏感通道的开放状态的可能结构。我们表明，在控制天然脂质环境中孔状态的同时，通过改变脂质双层的横向压力分布，类似于膜片钳记录，可以测量蛋白质的结构重排。与之前提出的方案相比，向开放状态的转变并不那么剧烈，而 N 端仍然锚定在细胞膜表面，它可以引导膜张力的倾斜或直接将膜张力转化为孔衬螺旋的构象。将在生理条件下获得的 FRET 数据与模拟相结合，对于研究一系列多聚体膜蛋白的构象变化可能具有重要价值。
