Wiebeler Christian, Rao Aditya G, Gärtner Wolfgang, Schapiro Igor
Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
Institut für Analytische Chemie, Fakultät für Chemie und Mineralogie, Universität Leipzig, 04103, Leipzig, Germany.
Angew Chem Int Ed Engl. 2019 Feb 11;58(7):1934-1938. doi: 10.1002/anie.201810266. Epub 2019 Jan 24.
The origin of the spectral shift from a red- to a green-absorbing form in a cyanobacteriochrome, Slr1393g3, was identified by combined quantum mechanics/molecular mechanics simulations. This protein, related to classical phytochromes, carries the open-chain tetrapyrrole chromophore phycocyanobilin. Our calculations reveal that the effective conjugation length in the chromophore becomes shorter upon conversion from the red to the green form. This is related to the planarity of the entire chromophore. A large distortion was found for the terminal pyrrole rings A and D; however, the D ring contributes more strongly to the photoproduct tuning, despite a larger change in the twist of the A ring. Our findings implicate that the D ring twist can be exploited to regulate the absorption of the photoproduct. Hence, mutations that affect the D ring twist can lead to rational tuning of the photoproduct absorption, allowing the tailoring of cyanobacteriochromes for biotechnological applications such as optogenetics and bioimaging.
通过量子力学/分子力学联合模拟确定了蓝细菌视紫红质Slr1393g3中从吸收红光形式到吸收绿光形式的光谱位移的起源。这种与经典植物色素相关的蛋白质携带开链四吡咯发色团藻蓝胆素。我们的计算表明，发色团从红色形式转变为绿色形式时，其有效共轭长度会变短。这与整个发色团的平面性有关。发现末端吡咯环A和D有很大的扭曲；然而，尽管A环的扭曲变化更大，但D环对光产物调谐的贡献更强。我们的研究结果表明，可以利用D环的扭曲来调节光产物的吸收。因此，影响D环扭曲的突变可以导致光产物吸收的合理调谐，从而能够为光遗传学和生物成像等生物技术应用定制蓝细菌视紫红质。
