Interaction of the PsbH subunit with a chlorophyll bound to histidine 114 of CP47 is responsible for the red 77 K fluorescence of Photosystem II
Interaction of the PsbH subunit with a chlorophyll bound to histidine 114 of CP47 is responsible for the red 77 K fluorescence of Photosystem II
复制标题
DOI：
10.1016/j.bbabio.2015.07.003
复制
发表时间：
2015-10-01
影响因子：
4.3
通讯作者：
Komenda, Josef
中科院分区：
文献类型：
--
作者：
D'Haene, Sandrine E.;Sobotka, Roman;Komenda, Josef
活性光系统II（PSII）复合物的特征是在约693 nm处的红移低温荧光发射。这种发射的起源归因于位于CP 47亚基中的单体“红色”叶绿素分子。然而，这种叶绿素的身份和功能仍然不确定。在我们以前的工作中，我们不能检测到的蓝细菌集胞藻属PCC 6803缺乏PsbH，一个小的跨膜亚基结合到CP 47的突变体中的红色PSII发射。然而，目前尚不清楚PsbH是否是结构上的红色发射所必需的或观察到的突变效应已间接引起的PSII的稳定性和功能受损。在目前的工作中，我们进行了详细的光谱表征的PSII在细胞中的突变缺乏PsbH和光系统I，我们还表征了PSII核心复合物从这个突变体分离。此外，我们纯化并表征了含有和缺乏PsbH的CP 47组装模块。这些结果清楚地证实了PsbH在PSII红色发射的起源中的重要作用，并且还表明PsbH稳定了PSII中一个β-胡萝卜素分子的结合。蓝细菌PSII的晶体结构表明，PsbH直接与一个单一的单体叶绿素连接的CP 47的组氨酸114残基，我们得出结论，这外围叶绿素氢键PsbH是负责红色荧光状态的CP 47。由于接近β-胡萝卜素，这种状态可能参与过多光能的耗散。(C)2015 Elsevier B. V.版权所有。
A characteristic feature of the active Photosystem II (PSII) complex is a red-shifted low temperature fluorescence emission at about 693 nm. The origin of this emission has been attributed to a monomeric 'red' chlorophyll molecule located in the CP47 subunit. However, the identity and function of this chlorophyll remain uncertain. In our previous work, we could not detect the red PSII emission in a mutant of the cyanobacterium Synechocystis sp. PCC 6803 lacking PsbH, a small transmembrane subunit bound to CP47. However, it has not been clear whether the PsbH is structurally essential for the red emission or the observed effect of mutation has been indirectly caused by compromised PSII stability and function. In the present work we performed a detailed spectroscopic characterization of PSII in cells of a mutant lacking PsbH and Photosystem I and we also characterized PSII core complexes isolated from this mutant. In addition, we purified and characterized the CP47 assembly modules containing and lacking PsbH. The results clearly confirm an essential role of PsbH in the origin of the PSII red emission and also demonstrate that PsbH stabilizes the binding of one beta-carotene molecule in PSII. Crystal structures of the cyanobacterial PSII show that PsbH directly interacts with a single monomeric chlorophyll ligated by the histidine 114 residue of CP47 and we conclude that this peripheral chlorophyll hydrogen-bonded to PsbH is responsible for the red fluorescence state of CP47. Given the proximity of p-carotene this state could participate in the dissipation of excessive light energy. (C) 2015 Elsevier B.V. All rights reserved.