Light drives photosynthesis. In plants it is absorbed by light-harvesting antenna complexes associated with Photosystem I (PSI) and photosystem II (PSII). As PSI and PSII work in series, it is important that the excitation pressure on the two photosystems is balanced. When plants are exposed to illumination that overexcites PSII, a special pool of the major light-harvesting complex LHCII is phosphorylated and moves from PSII to PSI (state 2). If instead PSI is over-excited the LHCII complex is dephosphorylated and moves back to PSII (state 1). Recent findings have suggested that LHCII might also transfer energy to PSI in state 1. In this work we used a combination of biochemistry and (time-resolved) fluorescence spectroscopy to investigate the PSI antenna size in state 1 and state 2 for Arabidopsis thaliana. Our data shows that 0.7 ± 0.1 unphosphorylated LHCII trimers per PSI are present in the stroma lamellae of state-1 plants. Upon transition to state 2 the antenna size of PSI in the stroma membrane increases with phosphorylated LHCIIs to a total of 1.2 ± 0.1 LHCII trimers per PSI. Both phosphorylated and unphosphorylated LHCII function as highly efficient PSI antenna.

中文翻译：

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在对远洋红光和蓝光进行处理后，对地黄酮敏感的LHCII会扩大拟南芥基质层中光系统I的天线。

光驱动光合作用。在植物中，它被与光系统I（PSI）和光系统II（PSII）相关的光收集天线复合体吸收。由于PSI和PSII串联工作，因此平衡两个光系统上的激发压力非常重要。当植物暴露于过度激发PSII的光照下时，主要采光复合物LHCII的特殊池就会被磷酸化，并从PSII转移到PSI（状态2）。相反，如果PSI过度兴奋，则LHCII复合物会被去磷酸化，然后回到PSII（状态1）。最近的发现表明，LHCII也可能在状态1下将能量转移到PSI。在这项工作中，我们结合了生物化学和（时间分辨）荧光光谱法研究拟南芥在状态1和状态2下的PSI天线尺寸。我们的数据表明0.7±0。状态1植物的基质层中存在每个PSI 1个未磷酸化的LHCII三聚体。过渡到状态2后，基质膜中PSI的天线尺寸随磷酸化LHCII的增加而增加，每个PSI总计为1.2±0.1 LHCII三聚体。磷酸化和未磷酸化的LHCII均可以用作高效的PSI天线。