Structural basis of dual Ca(2+)/pH regulation of the endolysosomal TRPML1 channel.
Structural basis of dual Ca(2+)/pH regulation of the endolysosomal TRPML1 channel.
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内溶酶体 TRPML1 通道 Ca2/pH 双重调节的结构基础。
DOI：
10.1038/nsmb.3362
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发表时间：
2017-03
影响因子：
16.8
通讯作者：
Yang J
中科院分区：
文献类型：
--
作者：
Li M;Zhang WK;Benvin NM;Zhou X;Su D;Li H;Wang S;Michailidis IE;Tong L;Li X;Yang J
细胞器离子通道对于细胞生理学是必不可少的。它们的活性通常受Ca ~（2+）和H ~+的调节，Ca ~（2+）和H ~+集中在许多细胞器中。在这里，我们报告了一种新的结构元素的关键Ca 2 +/pH值的双重调节TRPML 1，Ca 2+释放通道的内溶酶体功能至关重要。TRPML 1突变导致IV型粘脂沉积症（MLIV），这是一种严重的溶酶体贮积症，其特征在于神经变性、精神发育迟滞和失明。我们获得了高分辨率的晶体结构的213个氨基酸的管腔域的人TRPML 1，窝藏三个错义MLIV引起的突变。该结构域形成具有由新型管腔孔环形成的高度电负性中心孔的四聚体。半胱氨酸交联和cryo-EM证实了全长通道中的这种结构。结构-功能研究表明，Ca 2+和H+与腔孔相互作用，发挥重要的生理调节作用。导致MLIV的突变破坏管腔结构域结构并导致TRPML 1错误定位。我们的研究为TRPML 1的调节、组装和发病机制提供了结构基础。
Organellar ion channels are essential for cell physiology. Their activities are often regulated by Ca2+ and H+, which are concentrated in many organelles. Here we report a novel structural element critical for Ca2+/pH dual regulation of TRPML1, a Ca2+ release channel crucial for endolysosomal functions. TRPML1 mutations cause mucolipidosis type IV (MLIV), a severe lysosomal storage disorder characterized by neurodegeneration, mental retardation and blindness. We obtained high-resolution crystal structures of a 213-amino acid luminal domain of human TRPML1 that harbors three missense MLIV-causing mutations. This domain forms a tetramer with a highly electronegative central pore formed by a novel luminal pore-loop. Cysteine crosslinking and cryo-EM confirm this structure in the full-length channel. Structure-function studies demonstrate that Ca2+ and H+ interact with the luminal pore to exert physiologically important regulation. The MLIV-causing mutations disrupt the luminal domain structure and cause TRPML1 mislocalization. Our study provides a structural underpinning for TRPML1's regulation, assembly and pathogenesis.