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.
Nat Commun. 2019 Apr 30;10(1):1993. doi: 10.1038/s41467-019-10000-x.
Microbial rhodopsins are photoreceptive membrane proteins that transport various ions using light energy. While they are widely used in optogenetics to optically control neuronal activity, rhodopsins that function with longer-wavelength light are highly demanded because of their low phototoxicity and high tissue penetration. Here, we achieve a 40-nm red-shift in the absorption wavelength of a sodium-pump rhodopsin (KR2) by altering dipole moment of residues around the retinal chromophore (KR2 P219T/S254A) without impairing its ion-transport activity. Structural differences in the chromophore of the red-shifted protein from that of the wildtype are observed by Fourier transform infrared spectroscopy. QM/MM models generated with an automated protocol show that the changes in the electrostatic interaction between protein and chromophore induced by the amino-acid replacements, lowered the energy gap between the ground and the first electronically excited state. Based on these insights, a natural sodium pump with red-shifted absorption is identified from Jannaschia seosinensis.
微生物视紫红质是一种感光膜蛋白，它利用光能转运各种离子。虽然它们在光遗传学中被广泛用于光控神经元活动，但由于其光毒性低、组织穿透性高，对长波长光起作用的视紫红质的需求很高。在这里，我们通过改变视黄醛周围残基的偶极矩（KR2 P219T/S254A），在不损害其离子转运活性的情况下，将钠泵视紫红质（KR2）的吸收波长红移 40nm。傅里叶变换红外光谱观察到红移蛋白与野生型蛋白的生色团结构差异。使用自动协议生成的 QM/MM 模型表明，氨基酸取代引起的蛋白和生色团之间的静电相互作用的变化降低了基态和第一电子激发态之间的能隙。基于这些见解，从 Jannaschia seosinensis 中鉴定出一种具有红移吸收的天然钠泵。
