Mechanisms of photoprotection and nonphotochemical quenching in pea light-harvesting complex at 2.5A resolution
Mechanisms of photoprotection and nonphotochemical quenching in pea light-harvesting complex at 2.5A resolution
复制标题
DOI：
10.1038/sj.emboj.7600585
复制
发表时间：
2005-03-09
期刊：
影响因子：
11.4
通讯作者：
Kühlbrandt，W
中科院分区：
文献类型：
--
作者：
Standfuss，R;van Scheltinga，ACT;Kühlbrandt，W
植物光系统II捕光复合体（LHC-II）在叶绿体膜中收集和传输用于光合作用的太阳能，并在光合作用和光保护中发挥重要作用。豌豆LHC-II的2.5 μ m结构由堆叠的二维晶体的X射线晶体学确定，显示了膜如何相互作用形成叶绿体基粒，并揭示了LHC-II三聚体中42个叶绿素a和b，12个类胡萝卜素和6个脂质的相互排列。单个叶绿素的光谱分配表明在复杂的能量流和两个密切的叶绿素-叶黄素对的光保护机制。我们提出了一个简单的机制，叶黄素相关的，在LHC-II中的非光化学猝灭的缓慢成分，通过该机制，多余的能量被转移到玉米黄质取代其结合位点的紫黄质，并作为热量消散。我们的结构显示复合物处于淬灭状态，这可能与非光化学淬灭的快速pH诱导成分有关。
The plant light‐harvesting complex of photosystem II (LHC‐II) collects and transmits solar energy for photosynthesis in chloroplast membranes and has essential roles in regulation of photosynthesis and in photoprotection. The 2.5 Å structure of pea LHC‐II determined by X‐ray crystallography of stacked two‐dimensional crystals shows how membranes interact to form chloroplast grana, and reveals the mutual arrangement of 42 chlorophyllsaandb, 12 carotenoids and six lipids in the LHC‐II trimer. Spectral assignment of individual chlorophylls indicates the flow of energy in the complex and the mechanism of photoprotection in two close chlorophylla–lutein pairs. We propose a simple mechanism for the xanthophyll‐related, slow component of nonphotochemical quenching in LHC‐II, by which excess energy is transferred to a zeaxanthin replacing violaxanthin in its binding site, and dissipated as heat. Our structure shows the complex in a quenched state, which may be relevant for the rapid, pH‐induced component of nonphotochemical quenching.