Cryo-EM structure of the volume-regulated anion channel LRRC8D isoform identifies features important for substrate permeation
Cryo-EM structure of the volume-regulated anion channel LRRC8D isoform identifies features important for substrate permeation
复制标题
DOI：
10.1038/s42003-020-0951-z
复制
发表时间：
2020-05-15
影响因子：
5.9
通讯作者：
Nureki, Osamu
中科院分区：
文献类型：
--
作者：
Nakamura, Ryoki;Numata, Tomohiro;Nureki, Osamu
中村亮基等人报道了容积调节性阴离子通道LRRC8D异构体的冷冻电镜结构，该结构使有机化合物能够渗透进入细胞。与LRRC8A异构体相比，LRRC8D异构体具有更宽的细胞外孔以及一个可能在门控中起作用的细胞内N末端螺旋。富含亮氨酸重复序列8（LRRC8）蛋白家族成员由五种LRRC8A - E异构体组成，是容积调节性阴离子通道（VRAC）的成孔组分。LRRC8A和至少一种其他LRRC8异构体组装成异聚体以产生VRAC转运活性。尽管已有LRRC8A的结构，但除LRRC8A之外的LRRC8异构体如何对VRAC的功能多样性有贡献的结构基础仍然不清楚。在此，我们展示了人LRRC8D异构体的结构，它使有机底物能够通过VRAC渗透。LRRC8D同型六聚体结构呈现出一种二重对称排列，并且结合基于结构的电生理分析，揭示了两个关键特征。细胞外一侧的孔收缩比LRRC8A结构中的更宽，这可能解释了有机底物通透性增加的原因。此外，一个N末端螺旋从细胞内侧突出到孔中，并且可能对门控至关重要。
Ryoki Nakamura et al. report the cryo-EM structure of the volume-regulated anion channel LRRC8D isoform, which enables permeation of organic compounds into cells. Compared to the LRRC8A isoform, the LRRC8D isoform has a wider extracellular pore and an intracellular N-terminal helix that may function in gating.Members of the leucine-rich repeat-containing 8 (LRRC8) protein family, composed of the five LRRC8A-E isoforms, are pore-forming components of the volume-regulated anion channel (VRAC). LRRC8A and at least one of the other LRRC8 isoforms assemble into heteromers to generate VRAC transport activities. Despite the availability of the LRRC8A structures, the structural basis of how LRRC8 isoforms other than LRRC8A contribute to the functional diversity of VRAC has remained elusive. Here, we present the structure of the human LRRC8D isoform, which enables the permeation of organic substrates through VRAC. The LRRC8D homo-hexamer structure displays a two-fold symmetric arrangement, and together with a structure-based electrophysiological analysis, revealed two key features. The pore constriction on the extracellular side is wider than that in the LRRC8A structures, which may explain the increased permeability of organic substrates. Furthermore, an N-terminal helix protrudes into the pore from the intracellular side and may be critical for gating.