Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Japan.
Faculty of Science, Ibaraki University, Mito, Japan.
FEBS J. 2018 Dec;285(23):4359-4366. doi: 10.1111/febs.14679. Epub 2018 Oct 30.
Light-harvesting-1 (LH1)-reaction center (RC) super-complex is a membrane protein-pigment complex existing in purple photosynthetic bacteria, where LH1 absorbs light energy and transfers them rapidly and efficiently to RC to initiate the charge separation and electron transfer reactions. The structure of LH1-RC has been reported at relatively low resolutions from several different species of bacteria previously, but was solved at an atomic resolution recently from a thermophilic photosynthetic bacterium Thermochromatium tepidum. This high-resolution structure revealed the detailed organization of the super-complex including a number of unique features that are important for its functioning, such as a more intact RC structure, transporting routes for quinones to replace the bound Q as well as for the in-and-out of the closed LH1 ring, detailed coordinating environment of the Ca ions in LH1 important for the remarkable red shift of the absorption spectrum, as well as for the enhanced thermostability. These results thus greatly advance our understanding on the mechanisms of energy transfer, quinone exchange, the red shift in the LH1-Qy transition and the enhanced thermal stability, in this super-complex.
捕光色素 1（LH1）-反应中心（RC）超复合体是一种存在于紫色光合细菌中的膜蛋白-色素复合物，其中 LH1 吸收光能并迅速有效地将其传递到 RC，以引发电荷分离和电子转移反应。此前，已有来自几种不同细菌的相对较低分辨率的 LH1-RC 结构被报道，但最近从嗜热光合细菌 Thermochromatium tepidum 中以原子分辨率解决了该结构。该高分辨率结构揭示了超复合体的详细组织，包括一些对其功能很重要的独特特征，例如更完整的 RC 结构、醌类物质的传输途径以取代结合的 Q 以及 LH1 闭环的进出、LH1 中 Ca 离子的详细配位环境对吸收光谱的显著红移以及增强的热稳定性很重要。这些结果极大地促进了我们对该超复合体中能量转移、醌交换、LH1-Qy 跃迁的红移以及增强的热稳定性机制的理解。
