Release of thioredoxin via the mechanosensitive channel MscL during osmotic downshock of Escherichia coli cells
Release of thioredoxin via the mechanosensitive channel MscL during osmotic downshock of Escherichia coli cells
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DOI：
10.1074/jbc.273.41.26670
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发表时间：
1998-10-09
影响因子：
4.8
通讯作者：
Ghazi, E
中科院分区：
文献类型：
--
作者：
Ajouz, B;Berrier, C;Ghazi, E
大肠杆菌冷细胞具有几个机械敏感的离子通道，但只有MscL，具有最高的电导率，这是在最高的膜张力激活的通道，已被克隆。我们研究了MscL在渗透压下休克引起的流出中的假定参与，渗透压休克引起谷氨酸钾、海藻糖和甘氨酸甜菜碱从野生型细胞和缺乏MscL的细胞中释放。这两种菌株之间没有差异，但如本文对于甘氨酸甜菜碱所示，流出过程的极快速性表明其是通道介导的。渗透性下休克还诱导EDTA处理的细胞释放一些胞质蛋白。我们研究了硫氧还蛋白的释放，该蛋白从野生型细胞中完全释放，但被MscL（-）细胞保留。通过表达编码MscL的基因来恢复释放，因此MscL不是排泄细胞保护剂所必需的，但它在休克期间在体内打开并催化硫氧还蛋白和可能的其他小胞质蛋白的流出。由此可见，已知在较低张力下激活的其他机械敏感性通道也必须在渗透压休克期间打开。它们的打开和MscL的打开可以解释渗透压调节剂的快速释放。
Escherichia cold cells possess several mechanosensitive ion channels but only MscL, the channel with the highest conductance, which is activated at the highest membrane tension, has been cloned. We investigated the putative involvement of MscL in the effluxes caused by osmotic downshock, Osmotic shock caused the release of potassium glutamate, trehalose, and glycine betaine from wild type cells and cells lacking MscL. These was no difference between the two strains, brat the extreme rapidity of the efflux process, as shown herein for glycine betaine, suggests that it is channel-mediated. Osmotic downshock also induces the release of some cytosolic proteins from EDTA-treated cells. We investigated the release of thioredoxin, This protein was totally released from wild type cells but was retained by MscL(-) cells. Release was restored by expression of the gene coding for MscL, Thus MscL is not necessary for the excretion of osmoprotectants, but it does open in vivo during shock and catalyzes the efflux of thioredoxin and possibly other small cytosolic proteins. It follows that the other mechanosensitive channels, which are known to be activated at lower tension, must also open during osmotic shock, Their opening and that of MscL could account for the rapid release of osmolytes.