Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
FEBS Lett. 2013 Oct 11;587(20):3309-13. doi: 10.1016/j.febslet.2013.08.043. Epub 2013 Sep 10.
Channelrhodopsin is a cation channel with the unique property of being activated by light. To address structural changes of the open state of the channel, two variants, which contain either 1 or 2 wild-type cysteines, were derivatised with nitroxide spin label and subjected to electron paramagnetic resonance spectroscopy. Both variants contained the C128T mutation to trap the long-lived P3(520) state by illumination. Comparison of spin-spin distances in the dark state and after illumination reflect conformational changes in the conductive P3(520) state involving helices B and F. Spin distance measurements reveal that channelrhodopsin forms a dimer even in the absence of intermolecular N-terminal cysteines.
通道蛋白视紫红质是一种阳离子通道，具有被光激活的独特特性。为了解决通道开放状态的结构变化问题，两种变体被衍生化并用氮氧自由基自旋标记，然后进行电子顺磁共振波谱分析。这两种变体都包含 C128T 突变，通过光照将其捕获在长寿命的 P3(520)状态中。在黑暗状态和光照后的自旋-自旋距离比较反映了涉及螺旋 B 和 F 的导电 P3(520)状态中的构象变化。自旋距离测量表明，即使在没有分子间 N 端半胱氨酸的情况下，通道蛋白视紫红质也能形成二聚体。
