Theoretical Insights into the Mechanism of Wavelength Regulation in Blue-Absorbing Proteorhodopsin
Theoretical Insights into the Mechanism of Wavelength Regulation in Blue-Absorbing Proteorhodopsin
复制标题
吸蓝蛋白视紫红质波长调节机制的理论见解
DOI：
10.1021/acs.jpcb.9b08189
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Mertz, Blake
中科院分区：
文献类型：
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作者：
Lee, Choongkeun;Sekharan, Sivakumar;Mertz, Blake
视紫红质（PR）是一种光驱动的质子泵，最值得注意的是，它引领了越来越多的微生物视网膜蛋白的发现，这些蛋白处于光遗传学等领域的最前沿。两种变体，蓝色（BPR）和绿色（GPR）蛋白视紫质，已经进化到在海洋的不同深度收集光。PR中的颜色调节机制由105位的单个残基控制：在BPR中，它是谷氨酰胺，而在GPR中，它是亮氨酸。虽然大多数研究的光谱调谐机制，在PR集中在探地雷达，负责光谱调谐在BPR的电子环境的详细了解是缺乏的。在这项工作中，几个BPR模型进行了研究，使用量子力学/分子力学（QM/MM）的计算，以获得基本的见解BPR的颜色调谐机制。我们发现BPR光谱调谐的分子机制取决于两个几何参数：全反式视黄基发色团的键长交替和扭转角偏差。这两个参数都受到发色团结合口袋中氢键网络强度的影响，这表明BPR与其他微生物视紫红质不同。
Proteorhodopsin (PR) is a light-driven proton pump that is most notable for ushering in the discovery of an ever-increasing number of microbial retinal proteins that are at the forefront of fields such as optogenetics. Two variants, blue (BPR) and green (GPR) proteorhodopsin, have evolved to harvest light at different depths of the ocean. The color-tuning mechanism in PR is controlled by a single residue at position 105: in BPR it is a glutamine, whereas in GPR it is a leucine. Although the majority of studies on the spectral tuning mechanism in PR have focused on GPR, detailed understanding of the electronic environment responsible for spectral tuning in BPR is lacking. In this work, several BPR models were investigated using quantum mechanics/molecular mechanics (QM/MM) calculations to obtain fundamental insights into the color tuning mechanism of BPR. We find that the molecular mechanism of spectral tuning in BPR depends on two geometric parameters, the bond length alternation and the torsion angle deviation of the all-trans-retinyl chromophore. Both parameters are influenced by the strength of the hydrogen-bonded networks in the chromophore-binding pocket, which shows how BPR is different from other microbial rhodopsins.