Structure of the MscL homolog from Mycobacterium tuberculosis:: A gated mechanosensitive ion channel
Structure of the MscL homolog from Mycobacterium tuberculosis:: A gated mechanosensitive ion channel
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DOI：
10.1126/science.282.5397.2220
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发表时间：
1998-12-18
期刊：
影响因子：
56.9
通讯作者：
Rees, DC
中科院分区：
文献类型：
--
作者：
Chang, G;Spencer, RH;Rees, DC
机械敏感性离子通道在将细胞膜上的物理应力转换为电化学响应中起关键作用。大电导机械敏感通道MscL家族广泛分布于原核生物中，可能参与细胞内渗透压变化的调节。为了更好地理解这些通道功能的结构基础，通过X射线晶体学确定了来自结核分枝杆菌的MscL同系物的结构，分辨率为3.5埃。该通道被组织成一个同型五聚体，每个亚基含有两个跨膜α螺旋和第三个细胞质α螺旋。从细胞外侧，一个直径约18埃的充满水的开口通向一个孔，该孔内衬有亲水残基，该亲水残基在细胞质侧变窄至封闭的疏水顶点，该疏水顶点可能充当通道门。这种结构可以作为其他机械敏感性通道的模型，以及更广泛的五聚体配体门控离子通道，例如烟碱乙酰胆碱受体。
Mechanosensitive ion channels play a critical role in transducing physical stresses at the cell membrane into an electrochemical response. The MscL family of Large-conductance mechanosensitive channels is widely distributed among prokaryotes and may participate in the regulation of osmotic pressure changes within the cell. In an effort to better understand the structural basis for the function of these channels, the structure of the MscL homolog from Mycobacterium tuberculosis was determined by x-ray crystallography to 3.5 angstroms resolution. This channel is organized as a homopentamer, with each subunit containing two transmembrane cr helices and a third cytoplasmic alpha helix. From the extracellular side, a water-filled opening approximately 18 angstroms in diameter Leads into a pore Lined with hydrophilic residues which narrows at the cytoplasmic side to an occluded hydrophobic apex that may act as the channel gate. This structure may serve as a model for other mechanosensitive channels, as well as the broader class of pentameric ligand-gated ion channels exemplified by the nicotinic acetylcholine receptor.