Nanodiscs as a novel approach to resolve inter-protein energy transfer within the photosynthetic membrane of purple bacteria
Nanodiscs as a novel approach to resolve inter-protein energy transfer within the photosynthetic membrane of purple bacteria
复制标题
纳米圆盘作为解决紫色细菌光合膜内蛋白质间能量转移的新方法
DOI：
10.1016/j.bpj.2022.11.1368
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发表时间：
2023
影响因子：
3.4
通讯作者：
Hart, Stephanie M.
中科院分区：
文献类型：
--
作者：
Fiebig, Olivia C.;Wang, Dihao;Harris, Dvir;Toporik, Hila;Ji, Yi;Chuang, Chern;Nairat, Muath;Tong, Ashley L.;Ogren, John I.;Hart, Stephanie M.
紫色光合细菌捕获阳光并以几乎100%的量子效率将其转化为化学能：几乎每个被吸收的光子都会导致电荷分离。如此高的效率是通过位于光合膜上的光收集蛋白质天线网络中的一系列超快蛋白质间能量转移事件实现的。了解膜内蛋白质的组织如何导致有效的能量转移是设计高效的人工太阳能收集技术的必要条件。光收集复合物2 （LH2）蛋白是体内最常见的光收集蛋白，由于膜环境中蛋白质的异质组织，确定蛋白质间能量转移已被证明具有挑战性。在这项工作中，我们引入模型膜纳米盘作为一种新的技术，以一种可控的方式重建复杂的膜环境。通过形成足够大的纳米圆盘，我们可以直接解决蛋白质间的能量转移。通过控制纳米圆盘的大小，我们可以改变蛋白质间的距离，解决膜组织对能量传递速率的影响。结合超快瞬态吸收光谱、低温电子显微镜和量子化学计算，我们发现LH2配合物倾向于在膜中紧密结合（25 Å），能量传递速率为5.7 ps。结果表明，这些紧密堆积的LH2对于长距离能量传递很重要，因为25 Å距离与体内最常见的蛋白质间距离相似。总的来说，我们的工作将纳米片作为一个平台来研究复杂的能量转移事件和膜组织对关键生物过程的影响。
Photosynthetic purple bacteria capture sunlight and convert it to chemical energy with almost 100% quantum efficiency: almost every photon absorbed leads to charge separation. Such high efficiency is achieved through a series of ultrafast inter-protein energy transfer events within an antenna network of light-harvesting proteins located in the photosynthetic membrane. Understanding how the organization of proteins within the membrane leads to efficient energy transfer is imperative to designing efficient artificial solar harvesting techniques. Determining inter-protein energy transfer between light-harvesting complex 2 (LH2) proteins, the most common light-harvesting protein in vivo, has proven challenging due to the heterogeneous organization of proteins within the membrane environment. In this work, we introduce model membrane nanodiscs as a novel technique to reconstruct the complex membrane environment in a controlled manner. By forming nanodiscs large enough to incorporate two variants of LH2, we can directly resolve inter-protein energy transfer. By controlling nanodisc size, we can change the inter-protein distance and resolve the effect of membrane organization on energy transfer rate. Using a combination of ultrafast transient absorption spectroscopy, cryogenic electron microscopy, and quantum chemical calculations, we find that LH2 complexes prefer to associate closely in the membrane (25 Å), with an energy transfer rate of 5.7 ps. The results suggest that these tightly-packed LH2s are important for long-distance energy transfer, as the 25 Å distance is similar to the most common inter-protein distance in vivo. Overall, our work introduces nanodiscs as a platform to study complex energy transfer events and the effect of membrane organization on critical biological processes.