Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, China.
Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
Nat Commun. 2024 Aug 24;15(1):7292. doi: 10.1038/s41467-024-51811-x.
Channelrhodopsins are popular optogenetic tools in neuroscience, but remain poorly understood mechanistically. Here we report the cryo-EM structures of channelrhodopsin-2 (ChR2) from Chlamydomonas reinhardtii and H. catenoides kalium channelrhodopsin (KCR1). We show that ChR2 recruits an endogenous N-retinylidene-PE-like molecule to a previously unidentified lateral retinal binding pocket, exhibiting a reduced light response in HEK293 cells. In contrast, H. catenoides kalium channelrhodopsin (KCR1) binds an endogenous retinal in its canonical retinal binding pocket under identical condition. However, exogenous ATR reduces the photocurrent magnitude of wild type KCR1 and also inhibits its leaky mutant C110T. Our results uncover diverse retinal chromophores with distinct binding patterns for channelrhodopsins in mammalian cells, which may further inspire next generation optogenetics for complex tasks such as cell fate control.
通道蛋白型视紫红质是神经科学中流行的光遗传学工具，但在机制上仍了解甚少。在这里，我们报告了莱茵衣藻和 H. catenoides 钾通道蛋白型视紫红质（KCR1）的通道蛋白型视紫红质-2（ChR2）的冷冻电镜结构。我们表明，ChR2 将一种内源性 N-视黄醛-PE 样分子募集到一个以前未被识别的侧视网膜结合口袋中，在 HEK293 细胞中表现出降低的光反应。相比之下，在相同条件下，H. catenoides 钾通道蛋白型视紫红质（KCR1）将内源性视黄醛结合到其经典的视黄醛结合口袋中。然而，外源性 ATR 降低了野生型 KCR1 的光电流幅度，并且还抑制了其漏型突变体 C110T。我们的结果揭示了在哺乳动物细胞中具有不同结合模式的通道蛋白型视紫红质的不同视网膜发色团，这可能进一步激发下一代用于复杂任务的光遗传学，例如细胞命运控制。
