MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L69 7ZB Liverpool, United Kingdom.
Sci Adv. 2024 Oct 11;10(41):eadp6678. doi: 10.1126/sciadv.adp6678. Epub 2024 Oct 9.
The reaction center-light-harvesting complex 1 (RC-LH1) plays an essential role in the primary reactions of bacterial photosynthesis. Here, we present high-resolution structures of native monomeric and dimeric RC-LH1 supercomplexes from () using cryo-electron microscopy. The RC-LH1 monomer is composed of an RC encircled by an open LH1 ring comprising 15 αβ heterodimers and a PufX transmembrane polypeptide. In the RC-LH1 dimer, two crossing PufX polypeptides mediate dimerization. Unlike counterpart, RC-LH1 dimer has a less bent conformation, lacks the PufY subunit near the LH1 opening, and includes two extra LH1 αβ subunits, forming a more enclosed S-shaped LH1 ring. Spectroscopic assays reveal that these unique structural features are accompanied by changes in the kinetics of quinone/quinol trafficking between RC-LH1 and cytochrome . Our findings reveal the assembly principles and structural variability of photosynthetic RC-LH1 supercomplexes, highlighting diverse strategies used by phototrophic bacteria to optimize light-harvesting and electron transfer in competitive environments.
反应中心-捕光复合物 1（RC-LH1）在细菌光合作用的初级反应中起着至关重要的作用。在这里，我们使用冷冻电子显微镜呈现了来自（）的天然单体和二聚体 RC-LH1 超复合物的高分辨率结构。RC-LH1 单体由一个 RC 组成，RC 被一个由 15 个 αβ 异二聚体组成的开放 LH1 环包围，并包含一个 PufX 跨膜多肽。在 RC-LH1 二聚体中，两个交叉的 PufX 多肽介导二聚化。与（）的 RC-LH1 相比，RC-LH1 二聚体具有较少的弯曲构象，在 LH1 开口附近缺少 PufY 亚基，并且包含两个额外的 LH1 αβ 亚基，形成更封闭的 S 形 LH1 环。光谱测定表明，这些独特的结构特征伴随着 RC-LH1 和细胞色素之间醌/氢醌转运的动力学变化。我们的发现揭示了光合 RC-LH1 超复合物的组装原则和结构可变性，突出了光合细菌在竞争环境中优化光捕获和电子传递所采用的不同策略。
