Microsolvation Effects in the Spectral Tuning of Heliorhodopsin
Microsolvation Effects in the Spectral Tuning of Heliorhodopsin
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DOI：
10.1021/acs.jpcb.2c03672
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发表时间：
2022-07-27
影响因子：
3.3
通讯作者：
Gascon，Jose A.
中科院分区：
文献类型：
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作者：
Wijesiri，Kithmini;Gascon，Jose A.
向日葵红质(HER)是一类新的七螺旋跨膜光活性蛋白，具有共价连接的全视网膜结构。视网膜中的质子化席夫碱(PSB)氮由带负电荷的反离子稳定。众所周知，在微生物和动物视紫红质中，较强或较弱的静电与反离子的相互作用分别导致显著的光谱蓝移或红移。然而，在她的研究中，虽然Glu107起到了反离子的作用，但这种残基的突变与光谱变化并不直接相关。分子动力学分析表明，水团簇口袋在席夫碱上产生微溶剂化效应，在不同程度上补偿了天然反离子的取代。利用分子动力学和量子力学/分子力学(QM/MM)相结合的方法，我们研究了这种微溶剂化对HER的视黄基席夫碱发色团电子吸收的影响。
Heliorhodopsins (HeR) are a new category of heptahelical transmembrane photoactive proteins with a covalently linked all-transretinal. The protonated Schiff base (PSB) nitrogen in the retinal is stabilized by a negatively charged counterion. It is well-known that stronger or weaker electrostatic interactions with the counterion cause a significant spectral blue- or red-shift, respectively, in both microbial and animal rhodopsins. In HeR, however, while Glu107 acts as the counterion, mutations of this residue are not directly correlated with a spectral shift. A molecular dynamics analysis revealed that a water cluster pocket produces a microsolvation effect on the Schiff base, compensating to various extents the replacement of the native counterion. Using a combination of molecular dynamics and quantum mechanical/molecular mechanics (QM/MM), we study this microsolvation effect on the electronic absorption of the retinylidene Schiff base chromophore of HeR.