Structural changes of Salinibacter sensory rhodopsin I upon formation of the K and M photointermediates.-猫眼课题宝

K 和 M 光中间体形成后盐杆菌感觉视紫红质 I 的结构变化。

DOI：

10.1021/bi801358b

发表时间：

2008

期刊：

Biochemistry

影响因子：

2.9

通讯作者：

中科院分区：

生物学3区

文献类型：

作者：

D. Suzuki;Y. Sudo;Y. Furutani;Hazuki Takahashi;M. Homma;H. Kandori

感觉视紫红质I（Sensory Rhodopsin I，SRI）是自然界中最有趣的感光受体之一，因为它能够通过光致变色单光子和双光子反应介导依赖于光的颜色的相反信号。最近，我们从真杆菌Salinibacter ruber（SrSRI）的特点。该蛋白质允许获得关于SRI在其作用期间的结构和结构变化的更详细的信息。在本文中，傅里叶变换红外光谱（FTIR）应用于SrSRI，和光谱变化时，形成的K和M中间体进行了比较，与其他古菌视紫红质，SRI盐生盐杆菌（HsSRI），感觉视紫红质II（SRII），细菌视紫红质（BR），和盐视紫红质（HR）。光谱比较的氢平面外（HOOP）振动的视网膜生色团在K中间体显示，扩展choromophore失真发生在SrSRI和HsSRI，以及在SRII，而失真是本地化的席夫碱区域BR和HR。它出现的传感器和泵功能是可区分的HOOP模式的光谱特征。SRII中864 cm（-1）处的HOOP带对负趋光性很重要，但在SrSRI中不存在，这表明SRI和SRII之间的信号传递机制存在差异。在SrSRI、BR和SRII中，在2172 cm（-1）处观察到对质子泵很重要的强氢结合水分子。M中间体的形成伴随着在1753（+）和1743（-）cm（-1）处出现峰，这可分别解释为抗衡离子（Asp 72）的质子化信号和来自未鉴别羧酸的质子释放信号。在红外光谱与其它视紫红质比较的基础上，讨论了SrSRI的结构和结构变化。

Sensory rhodopsin I (SRI) is one of the most interesting photosensory receptors in nature because of its ability to mediate opposite signals depending on light color by photochromic one-photon and two-photon reactions. Recently, we characterized SRI from eubacterium Salinibacter ruber (SrSRI). This protein allows more detailed information about the structure and structural changes of SRI during its action to be obtained. In this paper, Fourier transform infrared (FTIR) spectroscopy is applied to SrSRI, and the spectral changes upon formation of the K and M intermediates are compared with those of other archaeal rhodopsins, SRI from Halobacterium salinarum (HsSRI), sensory rhodopsin II (SRII), bacteriorhodopsin (BR), and halorhodopsin (HR). Spectral comparison of the hydrogen out-of-plane (HOOP) vibrations of the retinal chromophore in the K intermediates shows that extended choromophore distortion takes place in SrSRI and HsSRI, as well as in SRII, whereas the distortion is localized in the Schiff base region in BR and HR. It appears that sensor and pump functions are distinguishable from the spectral feature of HOOP modes. The HOOP band at 864 cm(-1) in SRII, important for negative phototaxis, is absent in SrSRI, suggesting differences in signal transfer mechanism between SRI and SRII. The strongly hydrogen-bound water molecule, important for proton pumps, is observed at 2172 cm(-1) in SrSRI, as well as in BR and SRII. The formation of the M intermediate accompanies the appearance of peaks at 1753 (+) and 1743 (-) cm(-1), which can be interpreted as the protonation signal of the counterion (Asp72) and the proton release signal from an unidentified carboxylic acid, respectively. The structure and structural changes of SrSRI are discussed on the basis of the present infrared spectral comparisons with other rhodopsins.