Hsieh Shou-Ting, Zhang Lu, Ye De-Wei, Huang Xuhui, Cheng Yuan-Chung
Department of Chemistry, National Taiwan University, Taipei City, Taiwan.
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou, Fujian CN 350002, China.
Faraday Discuss. 2019 Jul 11;216(0):94-115. doi: 10.1039/c8fd00205c.
Here we present our theoretical investigations into the light reaction in the dimeric photosystem II (PSII) core complex. An effective model for excitation energy transfer (EET) and primary charge separation (CS) in the PSII core complex was developed, with model parameters constructed based on molecular dynamics (MD) simulation data. Compared to experimental results, we demonstrated that this model faithfully reproduces the absorption spectra of the RC and core light-harvesting complexes (CP43 and CP47) as well as the full EET dynamics among the chromophores in the PSII core complex. We then applied master equation simulations and network analysis to investigate detailed EET plus CS dynamics in the system, allowing us to identify key EET pathways and produce a coarse-grained cluster model for the light reaction in the dimeric PSII core complex. We show that non-equilibrium energy transfer channels play important roles in the efficient light harvesting process and that multiple EET pathways exist between subunits of PSII to ensure the robustness of light harvesting in the system. Furthermore, we revealed that inter-monomer energy transfer dominated by the coupling between the two CLA625 molecules enables efficient energy exchange between two CP47s in the dimeric PSII core complex, which leads to significant energy pooling in the CP47 domain during the light reaction. Our study provides a blueprint for the design of light harvesting in the PSII core and show that a structure-based approach using molecular dynamics simulations and quantum chemistry calculations can be effectively utilized to elucidate the dynamics of light harvesting in complex photosynthetic systems.
在此，我们展示了对二聚体光系统II（PSII）核心复合物中光反应的理论研究。我们开发了一种用于PSII核心复合物中激发能量转移（EET）和初级电荷分离（CS）的有效模型，其模型参数基于分子动力学（MD）模拟数据构建。与实验结果相比，我们证明该模型忠实地再现了反应中心（RC）和核心捕光复合物（CP43和CP47）的吸收光谱以及PSII核心复合物中发色团之间完整的EET动力学。然后，我们应用主方程模拟和网络分析来研究系统中详细的EET加CS动力学，这使我们能够识别关键的EET途径，并为二聚体PSII核心复合物中的光反应生成一个粗粒度的簇模型。我们表明，非平衡能量转移通道在高效的光捕获过程中发挥着重要作用，并且在PSII的亚基之间存在多条EET途径，以确保系统中光捕获的稳健性。此外，我们揭示了由两个CLA625分子之间的耦合主导的单体间能量转移能够使二聚体PSII核心复合物中的两个CP47之间进行有效的能量交换，这导致在光反应期间CP47结构域中出现显著的能量汇聚。我们的研究为PSII核心中的光捕获设计提供了蓝图，并表明基于分子动力学模拟和量子化学计算的基于结构的方法可以有效地用于阐明复杂光合系统中光捕获的动力学。
