Water channel structures analysed by electron crystallography.
Water channel structures analysed by electron crystallography.
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DOI：
10.1016/j.bbagen.2013.10.007
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发表时间：
2014-05
期刊：
影响因子：
--
通讯作者：
K. Tani;Y. Fujiyoshi
中科院分区：
文献类型：
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作者：
K. Tani;Y. Fujiyoshi
背景水通道蛋白（AQP）传输水的机制已经争论了二十年。 AQP 的水渗透现象似乎难以解释，因为 Grotthuss 机制不允许同时实现快速水渗透和通过水分子氢键抑制质子转移。 综述范围电子晶体学确定的 AQP1 结构首次提供了对快速水渗透的质子排斥机制的见解。尽管一些研究提供了有关基于 AQP 结构的机制的线索，但每种提出的机制仍然不完整。本综述的重点是通过电子晶体学解析的 AQP 功能和结构，试图填补在脂质不存在和存在的情况下研究结果之间的空白。主要结论无论测定方法如何，许多 AQP 结构都可以叠加。即使在缺乏脂质的条件下，AQP 折叠也能保留，但通道孔中的水排列不同。这种差异可以通过脂质双层中两个短螺旋形成的偶极矩来解释。此外，AQP双层二维晶体的结构分析表明其具有阵列形成和细胞粘附功能。一般意义电子晶体学研究结果不仅有助于解决一些水渗透机制，而且还阐明了AQP在膜中的多种功能。 AQP 在大脑中的作用仍然不清楚，但它们的多种活动可能对大脑和其他生物功能的调节很重要。本文是题为水通道蛋白的特刊的一部分。
BackgroundThe mechanisms underlying water transport through aquaporin (AQP) have been debated for two decades. The water permeation phenomenon of AQP seems inexplicable because the Grotthuss mechanism does not allow for simultaneous fast water permeability and inhibition of proton transfer through the hydrogen bonds of water molecules.Scope of reviewThe AQP1 structure determined by electron crystallography provided the first insights into the proton exclusion mechanism despite fast water permeation. Although several studies have provided clues about the mechanism based on the AQP structure, each proposed mechanism remains incomplete. The present review is focused on AQP function and structure solved by electron crystallography in an attempt to fill the gaps between the findings in the absence and presence of lipids.Major conclusionsMany AQP structures can be superimposed regardless of the determination method. The AQP fold is preserved even under conditions lacking lipids, but the water arrangement in the channel pore differs. The differences might be explained by dipole moments formed by the two short helices in the lipid bilayer. In addition, structure analyses of double-layered two-dimensional crystals of AQP suggest an array formation and cell adhesive function.General significanceElectron crystallography findings not only have contributed to resolve some of the water permeation mechanisms, but have also elucidated the multiple functions of AQPs in the membrane. The roles of AQPs in the brain remain obscure, but their multiple activities might be important in the regulation of brain and other biological functions. This article is part of a Special Issue entitled Aquaporins.