Structure of the water channel AqpZ from Escherichia coli revealed by electron crystallography
Structure of the water channel AqpZ from Escherichia coli revealed by electron crystallography
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DOI：
10.1006/jmbi.1999.3031
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发表时间：
1999-09-03
影响因子：
5.6
通讯作者：
Engel, A
中科院分区：
文献类型：
--
作者：
Ringler, P;Borgnia, MJ;Engel, A
分子水通道（水通道蛋白）允许活细胞通过水分子的快速和特异性扩散来适应渗透压变化。水通道蛋白存在于动物、植物、藻类、真菌和细菌中。在这里，我们提出了一个电子显微镜分析的最古老的水通道描述到目前为止：水通道蛋白Z（AqpZ）的大肠杆菌。一个重组AqpZ与聚（组氨酸）标签在N端已构建，过表达和纯化的同质性。用辛基葡糖苷溶解，纯化的AqpZ保持作为同四聚体缔合，并且当在脂质存在下通过透析重构时组装成高度有序的二维四聚体晶体，其晶胞尺寸a=B=95埃，γ =90度。负染晶格的三维重建揭示了p42（1）2的堆积排列，这也是在人红细胞水通道（AQP1）中观察到的。冷冻水合样品中AqpZ四聚体的8埃投影图与AQP 1的相似，与这些蛋白质之间的高序列同源性一致。(C)北京：科学出版社.
Molecular water channels (aquaporins) allow living cells to adapt to osmotic variations by rapid and specific diffusion of water molecules. Aquaporins are present in animals, plants, algae, fungi and bacteria. Here we present an electron microscopic analysis of the most ancient water channel described so far: the aquaporin Z (AqpZ) of Escherichia coli. A recombinant AqpZ with a poly(histidine) tag at the N terminus has been constructed, overexpressed and purified to homogeneity. Solubilized with octylglucoside, the purified AqpZ remains associated as a homotetramer, and assembles into highly ordered two-dimensional tetragonal crystals with unit cell dimensions a=b=95 Angstrom, gamma=90 degrees when reconstituted by dialysis in the presence of Lipids. Three-dimensional reconstruction of negatively stained lattices revealed the p42(1)2 packing arrangement that is also observed with the human erythrocyte water channel (AQP1). The 8 Angstrom projection map of the AqpZ tetramer in frozen hydrated samples is similar to that of AQP1, consistent with the high sequence homology between these proteins. (C) 1999 Academic Press.