Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic.
Umeå Plant Science Centre (UPSC), Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden.
Int J Mol Sci. 2022 Jan 11;23(2):778. doi: 10.3390/ijms23020778.
Antenna proteins play a major role in the regulation of light-harvesting in photosynthesis. However, less is known about a possible link between their sizes (oligomerization state) and fluorescence intensity (number of photons emitted). Here, we used a microscopy-based method, Fluorescence Correlation Spectroscopy (FCS), to analyze different antenna proteins at the particle level. The direct comparison indicated that Chromera Light Harvesting (CLH) antenna particles (isolated from ) behaved as the monomeric Light Harvesting Complex II (LHCII) (from higher plants), in terms of their radius (based on the diffusion time) and fluorescence yields. FCS data thus indicated a monomeric oligomerization state of algal CLH antenna (at our experimental conditions) that was later confirmed also by biochemical experiments. Additionally, our data provide a proof of concept that the FCS method is well suited to measure proteins sizes (oligomerization state) and fluorescence intensities (photon counts) of antenna proteins per single particle (monomers and oligomers). We proved that antenna monomers (CLH and LHCIIm) are more "quenched" than the corresponding trimers. The FCS measurement thus represents a useful experimental approach that allows studying the role of antenna oligomerization in the mechanism of photoprotection.
天线蛋白在光合作用中的光捕获调节中起着重要作用。然而，关于它们的大小（寡聚状态）和荧光强度（发射的光子数）之间可能存在的联系，人们知之甚少。在这里，我们使用基于显微镜的荧光相关光谱（FCS）分析了颗粒水平上的不同天线蛋白。直接比较表明，Chromera 光捕获（CLH）天线颗粒（从 Chromera velia 中分离得到）在半径（基于扩散时间）和荧光产率方面与单体光捕获复合物 II（LHCII）（来自高等植物）相似。因此，FCS 数据表明藻类 CLH 天线的单体寡聚状态（在我们的实验条件下），后来也通过生化实验得到了证实。此外，我们的数据还提供了一个概念证明，即 FCS 方法非常适合测量每个单个颗粒（单体和寡聚物）的天线蛋白的大小（寡聚状态）和荧光强度（光子数）。我们证明了天线单体（CLH 和 LHCIIm）比相应的三聚体更“猝灭”。因此，FCS 测量代表了一种有用的实验方法，可用于研究天线寡聚化在光保护机制中的作用。
