Kataoka Chihiro, Inoue Keiichi, Katayama Kota, Béjà Oded, Kandori Hideki
Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
J Phys Chem Lett. 2019 Sep 5;10(17):5117-5121. doi: 10.1021/acs.jpclett.9b01957. Epub 2019 Aug 21.
Light energy is first captured in animal and microbial rhodopsins by ultrafast photoisomerization, whose relaxation accompanies protein structural changes for each function. Here, we report a microbial rhodopsin, marine bacterial TAT rhodopsin, that displays no formation of photointermediates at >10 s. Low-temperature ultraviolet-visible and Fourier transform infrared spectroscopy revealed that TAT rhodopsin features all- to 13- photoisomerization like other microbial rhodopsins, but a planar 13- chromophore in the primary K intermediate seems to favor thermal back isomerization to the original state without photocycle completion. The molecular mechanism of the early photoreaction in TAT rhodopsin will be discussed.
光能首先在动物和微生物视紫红质中通过超快光异构化被捕获，其弛豫伴随着蛋白质结构的变化以实现每种功能。在此，我们报道了一种微生物视紫红质，即海洋细菌TAT视紫红质，它在超过10秒的时间内不形成光中间体。低温紫外可见光谱和傅里叶变换红外光谱显示，TAT视紫红质与其他微生物视紫红质一样具有全反式到13-顺式的光异构化，但初级K中间体中的平面13-发色团似乎有利于热逆向异构化回到原始状态，而不完成光循环。将讨论TAT视紫红质早期光反应的分子机制。
