Tsujimura Masaki, Noji Tomoyasu, Saito Keisuke, Kojima Keiichi, Sudo Yuki, Ishikita Hiroshi
Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan; Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
Biochim Biophys Acta Bioenerg. 2021 Feb 1;1862(2):148349. doi: 10.1016/j.bbabio.2020.148349. Epub 2020 Nov 26.
Using a quantum mechanical/molecular mechanical approach, we show the mechanisms of how the protein environment of Guillardia theta anion channelrhodopsin-1 (GtACR1) can shift the absorption wavelength. The calculated absorption wavelengths for GtACR1 mutants, M105A, C133A, and C237A are in agreement with experimentally measured wavelengths. Among 192 mutant structures investigated, mutations at Thr101, Cys133, Pro208, and Cys237 are likely to increase the absorption wavelength. In particular, T101A GtACR1 was expressed in HEK293T cells. The measured absorption wavelength is 10 nm higher than that of wild type, consistent with the calculated wavelength. (i) Removal of a polar residue from the Schiff base moiety, (ii) addition of a polar or acidic residue to the β-ionone ring moiety, and (iii) addition of a bulky residue to increase the planarity of the β-ionone and Schiff base moieties are the basis of increasing the absorption wavelength.
我们采用量子力学/分子力学方法，展示了吉氏衣藻阴离子通道视紫红质-1（GtACR1）的蛋白质环境改变吸收波长的机制。GtACR1突变体M105A、C133A和C237A的计算吸收波长与实验测量波长一致。在所研究的192个突变体结构中，苏氨酸101、半胱氨酸133、脯氨酸208和半胱氨酸237处的突变可能会增加吸收波长。特别是，T101A GtACR1在HEK293T细胞中表达。测得的吸收波长比野生型高10纳米，与计算波长一致。（i）从席夫碱部分去除一个极性残基，（ii）向β-紫罗兰酮环部分添加一个极性或酸性残基，以及（iii）添加一个大的残基以增加β-紫罗兰酮和席夫碱部分的平面度，是增加吸收波长的基础。
