Department of Advanced Interdisciplinary Studies, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan.
Commun Biol. 2022 Dec 6;5(1):1336. doi: 10.1038/s42003-022-04311-x.
Heliorhodopsin releases a proton from the Schiff base during the L-state to M-state transition but not toward the protein bulk surface. Here we investigate proton transfer and induced structural changes along the H-bond network in heliorhodopsin using a quantum mechanical/molecular mechanical approach and molecular dynamics simulations. Light-induced proton transfer could occur from the Schiff base toward Glu107, reorienting Ser76, followed by subsequent proton transfer toward His80. His80 protonation induces the reorientation of Trp246 on the extracellular surface, originating from the electrostatic interaction that propagates along the transmembrane H-bond network [His80…His23…HO…Gln26…Trp246] over a distance of 15 Å. Furthermore, it induces structural fluctuation on the intracellular side in the H-bond network [His80…Asn16…Tyr92…Glu230…Arg104…Glu149], opening the inner cavity at the Tyr92 moiety. These may be a basis of how light-induced proton transfer causes conformational changes during the M-state to O-state transition.
在 L 态到 M 态的转变过程中，盐藻视紫红质从 Schiff 碱释放质子，但不是朝向蛋白质的大部分表面。在这里，我们使用量子力学/分子力学方法和分子动力学模拟研究了质子转移和沿盐藻视紫红质氢键网络的诱导结构变化。光诱导的质子转移可以从 Schiff 碱向 Glu107 发生，重新定向 Ser76，随后向 His80 发生后续的质子转移。His80 的质子化诱导细胞外表面上的 Trp246 重新定向，这源于沿跨膜氢键网络传播的静电相互作用[His80…His23…HO…Gln26…Trp246]，距离为 15 Å。此外，它在氢键网络的细胞内一侧诱导结构波动[His80…Asn16…Tyr92…Glu230…Arg104…Glu149]，打开 Tyr92 部分的内腔。这些可能是光诱导质子转移在 M 态到 O 态转变过程中引起构象变化的基础。
