Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states
Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states
复制标题
DOI：
10.1038/ncomms3137
复制
发表时间：
2013-07-01
影响因子：
16.6
通讯作者：
Martinac, B.
中科院分区：
文献类型：
--
作者：
Cox, C. D.;Nomura, T.;Martinac, B.
小电导机械敏感通道（MscS）已在功能和结构水平上得到表征，并且在保护细菌细胞免受低渗休克中发挥着不可或缺的作用。在这里，我们通过记录脂质体贴片中野生型和突变型MscS单通道活性来研究细胞质结构域在MscS通道功能中的作用。我们报告说，当 Ca2+ 和 Ba2+ 离子是主要渗透阳离子时，MscS 在超极化电位下优先处于亚导状态。此外，我们的结果表明，靠近七个前庭门户的带电残基及其与渗透阳离子的静电相互作用决定了 MscS 和属于 MScS 亚家族的其他潜在通道的选择性并调节其电导。此外，我们的研究结果表明机械敏感通道在细菌钙调节中的作用，表明这些通道可能在细菌中发挥除防止渗透压变化之外的功能。
The mechanosensitive channel of small conductance (MscS) has been characterized at both functional and structural levels and has an integral role in the protection of bacterial cells against hypoosmotic shock. Here we investigate the role that the cytoplasmic domain has in MscS channel function by recording wild-type and mutant MscS single-channel activity in liposome patches. We report that MscS preferentially resides in subconducting states at hyperpolarising potentials when Ca2+ and Ba2+ ions are the major permeant cations. In addition, our results indicate that charged residues proximal to the seven vestibular portals and their electrostatic interactions with permeating cations determine selectivity and regulate the conductance of MscS and potentially other channels belonging to the MscS subfamily. Furthermore, our findings suggest a role for mechanosensitive channels in bacterial calcium regulation, indicative of functions other than protection against osmolarity changes that these channels possibly fulfil in bacteria.