Energy Transfer in Light-Adapted Photosynthetic Membranes: From Active to Saturated Photosynthesis
Energy Transfer in Light-Adapted Photosynthetic Membranes: From Active to Saturated Photosynthesis
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DOI：
10.1016/j.bpj.2009.08.033
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发表时间：
2009-11-04
影响因子：
3.4
通讯作者：
Johnson, Neil F.
中科院分区：
文献类型：
--
作者：
Fassioli, Francesca;Olaya-Castro, Alexandra;Johnson, Neil F.
在细菌光合作用捕光复合体中，LH 2和LH 1吸收太阳光能量，并以极高的效率将其传递到反应中心（RC）。亚分子分辨率的图像显示，LH 2：LH 1的比例，以及光合膜本身的结构，适应光强度。我们调查的功能意义的结构适应的能量传递性能在自然体内低和高光适应膜架构的Rhodocellum photometricum。一个模型来描述整个范围内的光强度，覆盖状态从活跃的光合作用，其中所有的RC可用于电荷分离，饱和的光合作用，其中所有的RC不可用的激发迁移。我们的研究概述了三个关键发现。首先，存在临界光能密度，低于该临界光能密度，低光适应膜比高光适应膜更有效地吸收光子并在RC处产生电荷分离。第二，核心复合物的连接性在两种膜中是相似的，这表明，尽管生长条件不同，但优选的转移途径是通过核心-核心接触。第三，就激发传递效率而言，膜上可能存在包含相同LH 2：LH 1比率的最小子区域，其表现为最小功能单元。
In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane architectures of Rhodospirillum photometricum. A model is presented to describe excitation migration across the full range of light intensities that cover states from active photosynthesis, where all RCs are available for charge separation, to saturated photosynthesis where all RCs are unavailable. Our study outlines three key findings. First, there is a critical light-energy density, below which the low-light adapted membrane is more efficient at absorbing photons and generating a charge separation at RCs, than the high-light-adapted membrane. Second, connectivity of core complexes is similar in both membranes, suggesting that, despite different growth conditions, a preferred transfer pathway is through core-core contacts. Third, there may be minimal subareas on the membrane which, containing the same LH2:LH1 ratio, behave as minimal functional units as far as excitation transfer efficiency is concerned.