Characterization of three novel mechanosensitive channel activities in Escherichia coli.
Characterization of three novel mechanosensitive channel activities in Escherichia coli.
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DOI：
10.4161/chan.20998
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发表时间：
2012-07
期刊：
影响因子：
--
通讯作者：
Booth IR
中科院分区：
文献类型：
--
作者：
Edwards MD;Black S;Rasmussen T;Rasmussen A;Stokes NR;Stephen TL;Miller S;Booth IR
当细胞从高渗透压环境移动到低渗透压环境（低渗透压休克）时，机械敏感通道感知到快速水流入引起的膜张力升高。这些细胞质膜上的非特异性通道释放具有渗透活性的溶质和离子。大肠杆菌的两个主要机械敏感通道是间充质干细胞和间充质干细胞。这两种蛋白的缺失严重损害了低渗休克的存活。然而，像许多细菌一样，大肠杆菌细胞具有其他msc型基因（kefA, ybdG, ybiO， yjeP和ynaI）。两个同源物，MscK （kefA）和YbdG，已被定性为机械敏感通道，在维持细胞完整性中起次要作用。在缺乏MscS、MscK和MscL的突变体衍生的斑块中偶尔会观察到额外的通道开放。由于它们很少发生，人们对这些额外的压力感应电流或它们的基因起源知之甚少。在此我们完成了剩余的大肠杆菌机械敏感通道YnaI， YbiO和YjeP的鉴定。后者是先前描述的MscM活性的主要成分（~300 pS），而YnaI （~100 pS）和YbiO （~1000 pS）先前未知。原生YbiO的表达是nacl特异性和rpos依赖性的。一个Δ7菌株被删除了所有7个大肠杆菌机械敏感通道基因。在Δ7菌株（MJFGH）中，来自多拷贝质粒的YnaI， YbiO或YjeP蛋白的高水平表达导致对低渗休克的实质性保护。纯化的同源物表现出与七聚体组装一致的高分子质量。这项工作揭示了新的机械敏感通道，并在可能的附加功能的背景下讨论了它们的表达调节。
Mechanosensitive channels sense elevated membrane tension that arises from rapid water influx occurring when cells move from high to low osmolarity environments (hypoosmotic shock). These non-specific channels in the cytoplasmic membrane release osmotically-active solutes and ions. The two major mechanosensitive channels in Escherichia coli are MscL and MscS. Deletion of both proteins severely compromises survival of hypoosmotic shock. However, like many bacteria, E. coli cells possess other MscS-type genes (kefA, ybdG, ybiO, yjeP and ynaI). Two homologs, MscK (kefA) and YbdG, have been characterized as mechanosensitive channels that play minor roles in maintaining cell integrity. Additional channel openings are occasionally observed in patches derived from mutants lacking MscS, MscK and MscL. Due to their rare occurrence, little is known about these extra pressure-induced currents or their genetic origins. Here we complete the identification of the remaining E. coli mechanosensitive channels YnaI, YbiO and YjeP. The latter is the major component of the previously described MscM activity (~300 pS), while YnaI (~100 pS) and YbiO (~1000 pS) were previously unknown. Expression of native YbiO is NaCl-specific and RpoS-dependent. A Δ7 strain was created with all seven E. coli mechanosensitive channel genes deleted. High level expression of YnaI, YbiO or YjeP proteins from a multicopy plasmid in the Δ7 strain (MJFGH) leads to substantial protection against hypoosmotic shock. Purified homologs exhibit high molecular masses that are consistent with heptameric assemblies. This work reveals novel mechanosensitive channels and discusses the regulation of their expression in the context of possible additional functions.
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影响因子：
11.4
作者：
Li, YZ;Moe, PC;Blount, P
通讯作者：
Blount, P
影响因子：
3.2
作者：
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通讯作者：
Church, GM
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2.7
作者：
Conway, T;Kraus, B;McKibben, L
通讯作者：
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作者：
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通讯作者：
Schellhorn, Herb
影响因子：
16.8
作者：
Edwards, MD;Li, YZ;Booth, IR
通讯作者：
Booth, IR