The fluoride permeation pathway and anion recognition in Fluc family fluoride channels.
The fluoride permeation pathway and anion recognition in Fluc family fluoride channels.
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DOI：
10.7554/elife.69482
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发表时间：
2021-07-12
期刊：
影响因子：
7.7
通讯作者：
Stockbridge RB
中科院分区：
文献类型：
--
作者：
McIlwain BC;Gundepudi R;Koff BB;Stockbridge RB
Fluc 家族氟化物通道通过破坏这种有毒卤化物的细胞质积累来保护微生物免受周围环境氟化物的侵害。这些蛋白质在结构上是特殊的，因此渗透途径和机制在其他已知的离子通道中没有类似物。尽管在之前的结构研究中已经确定了氟化物结合位点，但这些离子如何进入水溶液尚不清楚，并且阴离子识别和选择性的分子决定因素尚未阐明。利用 X 射线晶体学、平面双层电生理学和基于脂质体的测定，我们确定了渗透途径上的其他结合位点。我们利用这些信息开发了一种用于平面脂质双层电生理学的定向系统，并在这些位点之一观察到阴离子块，揭示了对阴离子识别机制的见解。我们提出了一种渗透机制，涉及交替占据阴离子结合位点，这些位点仅在底物接近时才完全组装。
Fluc family fluoride channels protect microbes against ambient environmental fluoride by undermining the cytoplasmic accumulation of this toxic halide. These proteins are structurally idiosyncratic, and thus the permeation pathway and mechanism have no analogy in other known ion channels. Although fluoride-binding sites were identified in previous structural studies, it was not evident how these ions access aqueous solution, and the molecular determinants of anion recognition and selectivity have not been elucidated. Using x-ray crystallography, planar bilayer electrophysiology, and liposome-based assays, we identified additional binding sites along the permeation pathway. We used this information to develop an oriented system for planar lipid bilayer electrophysiology and observed anion block at one of these sites, revealing insights into the mechanism of anion recognition. We propose a permeation mechanism involving alternating occupancy of anion-binding sites that are fully assembled only as the substrate approaches.