Iwai Masakazu, Yokono Makio, Nakano Akihiko
1] Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan [2] PRESTO, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012 Japan.
Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido 060-0819 Japan.
Sci Rep. 2014 Jan 20;4:3768. doi: 10.1038/srep03768.
To optimize photosynthesis, light-harvesting antenna proteins regulate light energy dissipation and redistribution in chloroplast thylakoid membranes, which involve dynamic protein reorganization of photosystems I and II. However, direct evidence for such protein reorganization has not been visualized in live cells. Here we demonstrate structural dynamics of thylakoid membranes by live cell imaging in combination with deconvolution. We observed chlorophyll fluorescence in the antibiotics-induced macrochloroplast in the moss Physcomitrella patens. The three-dimensional reconstruction uncovered the fine thylakoid membrane structure in live cells. The time-lapse imaging shows that the entire thylakoid membrane network is structurally stable, but the individual thylakoid membrane structure is flexible in vivo. Our observation indicates that grana serve as a framework to maintain structural integrity of the entire thylakoid membrane network. Both the structural stability and flexibility of thylakoid membranes would be essential for dynamic protein reorganization under fluctuating light environments.
为了优化光合作用，捕光天线蛋白调节叶绿体类囊体膜中的光能耗散和重新分配，这涉及光系统I和II的动态蛋白质重组。然而，这种蛋白质重组的直接证据尚未在活细胞中可视化。在这里，我们通过活细胞成像结合去卷积来证明类囊体膜的结构动态。我们在苔藓小立碗藓中观察了抗生素诱导的大叶绿体中的叶绿素荧光。三维重建揭示了活细胞中精细的类囊体膜结构。延时成像表明，整个类囊体膜网络在结构上是稳定的，但单个类囊体膜结构在体内是灵活的。我们的观察表明，基粒作为维持整个类囊体膜网络结构完整性的框架。类囊体膜的结构稳定性和灵活性对于在波动光环境下的动态蛋白质重组都是必不可少的。
