Joint Institute for Biological Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37830, United States.
Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee, 37916, United States.
Sci Rep. 2018 Sep 11;8(1):13607. doi: 10.1038/s41598-018-31945-x.
Channels without canonical voltage sensors can be modulated by voltage acting on other domains. Here we show that besides protein dipoles, pore hydration can be affected by electric fields. In patches, both WT MscL and its V23T mutant show a decrease in the tension midpoint with hyperpolarization. The mutant exhibits a stronger parabolic dependence of transition energy on voltage, highly consistent with the favourable dielectric contribution from water filling the expanding pore. Purified V23T MscL in DPhPC droplet interface bilayers shows a similar voltage dependence. When reconstituted in an asymmetric DOPhPC/DPhPC bilayer carrying a permanent bias of ~130 mV due to a dipole potential difference between the interfaces, the channel behaved as if the local intramembrane electric field sets the tension threshold for gating rather than just the externally applied voltage. The data emphasize the roles of polarized water in the pore and interfacial lipid dipoles in channel gating thermodynamics.
无规范电压传感器的通道可以通过作用于其他结构域的电压进行调节。在这里，我们表明除了蛋白质偶极子外，孔隙水合作用也可以受到电场的影响。在膜片中，WT MscL 及其 V23T 突变体均表现出超极化时张力中点的降低。该突变体显示出跃迁能量对电压的更强烈的抛物线依赖性，这与填充扩展孔的水的有利介电贡献高度一致。在 DPhPC 液滴界面双层中的纯化 V23T MscL 显示出相似的电压依赖性。当在由于界面之间的偶极电势差而带有约 130 mV 恒定偏置的不对称 DOPhPC/DPhPC 双层中再构成时，通道的行为就好像局部跨膜内电场为门控设定张力阈值，而不仅仅是外部施加的电压。这些数据强调了极化水在孔中和界面脂质偶极子在通道门控热力学中的作用。
