Lunde C, Jensen P E, Haldrup A, Knoetzel J, Scheller H V
Department of Plant Biology, The Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Nature. 2000 Nov 30;408(6812):613-5. doi: 10.1038/35046121.
Photosynthesis in plants involves two photosystems responsible for converting light energy into redox processes. The photosystems, PSI and PSII, operate largely in series, and therefore their excitation must be balanced in order to optimize photosynthetic performance. When plants are exposed to illumination favouring either PSII or PSI they can redistribute excitation towards the light-limited photosystem. Long-term changes in illumination lead to changes in photosystem stoichiometry. In contrast, state transition is a dynamic mechanism that enables plants to respond rapidly to changes in illumination. When PSII is favoured (state 2), the redox conditions in the thylakoids change and result in activation of a protein kinase. The kinase phosphorylates the main light-harvesting complex (LHCII) and the mobile antenna complex is detached from PSII. It has not been clear if attachment of LHCII to PSI in state 2 is important in state transitions. Here we show that in the absence of a specific PSI subunit, PSI-H, LHCII cannot transfer energy to PSI, and state transitions are impaired.
植物中的光合作用涉及两个负责将光能转化为氧化还原过程的光系统。光系统I（PSI）和光系统II（PSII）在很大程度上是串联运行的，因此它们的激发必须保持平衡，以优化光合作用性能。当植物受到有利于PSII或PSI的光照时，它们可以将激发重新分配到受光限制的光系统。光照的长期变化会导致光系统化学计量的变化。相比之下，状态转换是一种动态机制，使植物能够对光照变化迅速做出反应。当PSII占优势时（状态2），类囊体中的氧化还原条件发生变化，导致蛋白激酶激活。该激酶使主要的捕光复合体（LHCII）磷酸化，移动天线复合体从PSII上脱离。目前尚不清楚状态2中LHCII与PSI的结合在状态转换中是否重要。在这里，我们表明，在没有特定的PSI亚基PSI-H的情况下，LHCII无法将能量转移到PSI，状态转换也会受损。
