Characterization of mechanosensitive channels in Escherichia coli cytoplasmic membrane by whole-cell patch clamp recording.
Characterization of mechanosensitive channels in Escherichia coli cytoplasmic membrane by whole-cell patch clamp recording.
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通过全细胞膜片钳记录表征大肠杆菌细胞质膜中的机械敏感通道。
DOI：
10.1007/bf00238414
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Adler,J
中科院分区：
文献类型：
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作者：
Cui,C;Smith,DO;Adler,J
用全细胞膜片钳技术对大肠杆菌的巨大原生质体进行记录。研究了原生质体的压力敏感性。在400 mm KCl溶液中，对细胞内部施加正压或向下冲击细胞时，观察到两种不同单位电导的机械敏感通道，分别为1100 ± 25 pS和350 ± 14 pS。1100 pS电导通道在测试的单价离子中区分不佳，并且它对Ca 2+和谷氨酸-是可渗透的。两个通道都对跨膜的渗透梯度敏感;通道的单位电导保持恒定，而细胞的平均电流通过增加渗透梯度而增加。两个通道都是电压敏感的。电压斜坡实验结果表明，原生质体的压力敏感性是电压依赖性的：去极化时激活的通道多于超极化时激活的通道。钆离子可可逆性阻断该通道。它们也能被质子可逆地抑制。在两个钾外排系统，KefB和KefC的突变，不影响通道的活性，而在基因KefA的无效突变改变了通道的活性显着。这表明KefA对这些通道的潜在调节。
Whole-cell patch clamp recordings were done on giant protoplasts ofEscherichia coli. The pressure sensitivity of the protoplasts was studied. Two different unit conductance mechanosensitive channels, 1100 ± 25 pS and 350 ± 14 pS in 400 mmsymmetric KCl solution, were observed upon either applying positive pressure to the interior of the cells or down shocking the cells osmotically. The 1100 pS conductance channel discriminated poorly among the monovalent ions tested and it was permeable to Ca2+and glutamate−. Both of the two channels were sensitive to the osmotic gradient across the membrane; the unit conductances of the channels remained constant while the mean current of the cell was increased by increasing the osmotic gradient. Both of the channels were voltage sensitive. Voltage-ramp results showed that the pressure sensitivity of protoplasts was voltage dependent: there were more channels active upon depolarization than hyperpolarization. The mech anosensitive channels were reversibly blocked by gadolinium ion. Also they could reversibly be inhibited by protons. Mutations in two of the potassium efflux systems, KefB and KefC, did not affect the channel activity, while a null mutation in the gene for KefA changed the channel activity significantly. This indicates a potential modulation of these channels by KefA.