Max Planck Institute of Biophysics Department of Structural Biology, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
Max Planck Institute of Biophysics Department of Biophysical Chemistry, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
J Mol Biol. 2015 Jan 30;427(2):341-9. doi: 10.1016/j.jmb.2014.11.004. Epub 2014 Nov 9.
Channelrhodopsin-2 (ChR2) is a cation-selective light-gated channel from Chlamydomonas reinhardtii (Nagel G, Szellas T, Huhn W, Kateriya S, Adeishvili N, Berthold P, et al. Channelrhodopsin-2, a directly light-gated cation-selective membrane channel. Proc Natl Acad Sci USA 2003;100:13940-5), which has become a powerful tool in optogenetics. Two-dimensional crystals of the slow photocycling C128T ChR2 mutant were exposed to 473 nm light and rapidly frozen to trap the open state. Projection difference maps at 6Å resolution show the location, extent and direction of light-induced conformational changes in ChR2 during the transition from the closed state to the ion-conducting open state. Difference peaks indicate that transmembrane helices (TMHs) TMH2, TMH6 and TMH7 reorient or rearrange during the photocycle. No major differences were found near TMH3 and TMH4 at the dimer interface. While conformational changes in TMH6 and TMH7 are known from other microbial-type rhodopsins, our results indicate that TMH2 has a key role in light-induced channel opening and closing in ChR2.
通道视紫红质 2（ChR2）是一种来自莱茵衣藻（Nagel G、Szellas T、Huhn W、Kateriya S、Adeishvili N、Berthold P 等人的阳离子选择性光门通道。通道视紫红质 2，一种直接光控阳离子选择性膜通道。Proc Natl Acad Sci USA 2003；100：13940-5），已成为光遗传学的有力工具。暴露于 473nm 光的慢光循环 C128T ChR2 突变体的二维晶体被迅速冷冻以捕获开放状态。在从关闭状态到离子传导开放状态的转变过程中，6Å 分辨率的投影差异图显示了 ChR2 中光诱导构象变化的位置、程度和方向。差异峰表明，在光循环过程中，跨膜螺旋（TMH）TMH2、TMH6 和 TMH7 重新定向或重新排列。在二聚体界面处的 TMH3 和 TMH4 附近没有发现明显差异。虽然来自其他微生物型视紫红质的 TMH6 和 TMH7 的构象变化是已知的，但我们的结果表明 TMH2 在 ChR2 中的光诱导通道打开和关闭中起关键作用。
