Role of Pore-Lining Residues in Defining the Rate of Water Conduction by Aquaporin-0.
Role of Pore-Lining Residues in Defining the Rate of Water Conduction by Aquaporin-0.
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孔衬残留物在确定 Aquaporin-0 水传导速率中的作用。
DOI：
10.1016/j.bpj.2017.01.026
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发表时间：
2017
影响因子：
3.4
通讯作者：
Walz,Thomas
中科院分区：
文献类型：
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作者：
Saboe,PatrickO;Rapisarda,Chiara;Kaptan,Shreyas;Hsiao,Yu-Shan;Summers,SamanthaR;DeZorzi,Rita;Dukovski,Danijela;Yu,Jiaheng;deGroot,BertL;Kumar,Manish;Walz,Thomas
与其他水通道蛋白相比，晶状体特异性水通道蛋白0是一种较差的水通道，其渗透性具有pH依赖性。迄今为止，大多数水传导研究AQP 0的蛋白质表达inXenopusoacytes进行，因此，结果也可能反映卵母细胞本身的影响。用纯化的AQP 0重组到脂质体中的实验是具有挑战性的，因为AQP 0的水渗透性仅略高于纯脂质双层。通过重组大量的AQP 0和使用高浓度的胆固醇来降低脂质双层的渗透性，我们提高了对AQP 0脂蛋白体的水渗透性测量的信噪比。我们的测量结果表明，突变的两个孔衬酪氨酸残基，Tyr-23和Tyr-149在绵羊AQP 0中，相应的残基在高渗透性水通道AQP 1具有累加效应，并一起增加水通道AQP 0的40倍的水渗透性的水平，相当于AQP 1。分子动力学模拟定性地支持这些实验结果，并表明，突变的Tyr-23改变孔分布在由残基Arg-187形成的门。
Compared to other aquaporins (AQPs), lens-specific AQP0 is a poor water channel, and its permeability was reported to be pH-dependent. To date, most water conduction studies on AQP0 were performed on protein expressed inXenopusoocytes, and the results may therefore also reflect effects introduced by the oocytes themselves. Experiments with purified AQP0 reconstituted into liposomes are challenging because the water permeability of AQP0 is only slightly higher than that of pure lipid bilayers. By reconstituting high amounts of AQP0 and using high concentrations of cholesterol to reduce the permeability of the lipid bilayer, we improved the signal-to-noise ratio of water permeability measurements on AQP0 proteoliposomes. Our measurements show that mutation of two pore-lining tyrosine residues, Tyr-23 and Tyr-149 in sheep AQP0, to the corresponding residues in the high-permeability water channel AQP1 have additive effects and together increase the water permeability of AQP0 40-fold to a level comparable to that of AQP1. Molecular dynamics simulations qualitatively support these experimental findings and suggest that mutation of Tyr-23 changes the pore profile at the gate formed by residue Arg-187.