A Structure-Based Model of Energy Transfer Reveals the Principles of Light Harvesting in Photosystem II Supercomplexes
A Structure-Based Model of Energy Transfer Reveals the Principles of Light Harvesting in Photosystem II Supercomplexes
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DOI：
10.1021/ja403685a
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发表时间：
2013-06-19
影响因子：
15
通讯作者：
Fleming, Graham R.
中科院分区：
文献类型：
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作者：
Bennett, Doran I. G.;Amarnath, Kapil;Fleming, Graham R.
光系统II（PSII）通过吸收光并随后通过电荷分离将激发能转化为化学能来启动植物中的光合作用。与PSII相关的色素结合蛋白在基粒膜中组装成PSII超复合物和周围的捕光复合物II三聚体。为了理解光系统II的高效捕光，需要对光系统II超复合物中的能量转移和电荷分离进行定量研究。我们构建了第一个基于结构的PSII超复合物中能量传递模型。该模型表明，光捕获的动力学不能被简化为一个单一的速率限制步骤。相反，激发通过天线色素的扩散和从天线转移到反应中心（RC）（在那里发生电荷分离）都产生了实质性的贡献。由于缺乏一个限速步骤，拟合动力学模型的荧光寿命数据不能用于获得光捕获在PSII的机制的见解。这个模型将澄清解释叶绿素荧光数据从PSII超复合物，基粒膜，和叶子。
Photosystem II (PSII) initiates photosynthesis in plants through the absorption of light and subsequent conversion of excitation energy to chemical energy via charge separation. The pigment binding proteins associated with PSII assemble in the grana membrane into PSII supercomplexes and surrounding light harvesting complex II trimers. To understand the high efficiency of light harvesting in PSII requires quantitative insight into energy transfer and charge separation in PSII supercomplexes. We have constructed the first structure-based model of energy transfer in PSII supercomplexes. This model shows that the kinetics of light harvesting cannot be simplified to a single rate limiting step. Instead, substantial contributions arise from both excitation diffusion through the antenna pigments and transfer from the antenna to the reaction center (RC), where charge separation occurs. Because of the lack of a rate-limiting step, fitting kinetic models to fluorescence lifetime data cannot be used to derive mechanistic insight on light harvesting in PSII. This model will clarify the interpretation of chlorophyll fluorescence data from PSII supercomplexes, grana membranes, and leaves.