Dual Ca2+-dependent gates in human Bestrophin1 underlie disease-causing mechanisms of gain-of-function mutations
Dual Ca2+-dependent gates in human Bestrophin1 underlie disease-causing mechanisms of gain-of-function mutations
复制标题
人 Bestropin1 中的双 Ca2 依赖性门是功能获得性突变致病机制的基础
DOI：
10.1038/s42003-019-0433-3
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发表时间：
2019-06-24
影响因子：
5.9
通讯作者：
Yang, Tingting
中科院分区：
文献类型：
--
作者：
Ji, Changyi;Kittredge, Alec;Yang, Tingting
编码Ca 2+激活的Cl-通道（hBest 1）的人类BEST 1的突变引起黄斑变性疾病。Best 1同源结构揭示了离子传导途径中两个具有里程碑意义的限制（分别称为“颈”和“孔”）所强调的进化保守的通道结构，表明了独特的双开关门控机制，然而，该机制尚未得到很好的表征。使用膜片钳和晶体学，我们证明hBest 1中的颈部和孔都是Ca 2+依赖性门，对于防止Ca 2+非依赖性自发门开放导致的通道泄漏至关重要。重要的是，三个患者来源的突变（D203 A，I205 T和Y236 C）导致Ca 2+非依赖性泄漏和升高的Ca 2+依赖性阴离子电流，这是由于门的打开增强。此外，我们确定了一个网络的残基关键参与门操作。总之，我们的研究结果表明，hBest 1的颈部和孔径对于通道门控起着不可或缺的作用，并揭示了hBest 1功能获得性突变的致病机制。
Mutations of human BEST1, encoding a Ca2+-activated Cl- channel (hBest1), cause macular degenerative disorders. Best1 homolog structures reveal an evolutionarily conserved channel architecture highlighted by two landmark restrictions (named the "neck" and "aperture", respectively) in the ion conducting pathway, suggesting a unique dual-switch gating mechanism, which, however, has not been characterized well. Using patch clamp and crystallography, we demonstrate that both the neck and aperture in hBest1 are Ca2+-dependent gates essential for preventing channel leakage resulting from Ca2+-independent, spontaneous gate opening. Importantly, three patient-derived mutations (D203A, I205T and Y236C) lead to Ca2+-independent leakage and elevated Ca2+-dependent anion currents due to enhanced opening of the gates. Moreover, we identify a network of residues critically involved in gate operation. Together, our results suggest an indispensable role of the neck and aperture of hBest1 for channel gating, and uncover disease-causing mechanisms of hBest1 gain-of-function mutations.