Live-cell imaging of photosystem II antenna dissociation during state transitions
Live-cell imaging of photosystem II antenna dissociation during state transitions
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DOI：
10.1073/pnas.0908808107
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发表时间：
2010-02-02
影响因子：
11.1
通讯作者：
Minagawa, Jun
中科院分区：
文献类型：
--
作者：
Iwai, Masakazu;Yokono, Makio;Minagawa, Jun
植物和绿藻在不断变化的光环境下通过调节自身的光收集能力来维持高效的光合作用。有研究认为，光系统II （PSII）和光系统I (PSI)（状态转换）之间的光收集天线复合体II （LHCII）的穿梭可以带来能量再分配，但这种分子重塑从未在体内得到证实。利用叶绿素荧光寿命成像显微镜，我们观察了莱茵衣藻（Chlamydomonas reinhardtii）活细胞中磷酸- lhcii与PSII的分离。在野生型细胞中，诱导能量再分配导致250-ps寿命的叶绿素荧光成分增加和扩散，而在不能状态转换的stt7突变体中没有观察到这一点。在含有光收集天线复合物但不含光系统的突变体中，250-ps组分也是显性组分。250-ps组分的出现伴随着LHCII磷酸化的激活，支持了磷酸化-LHCII解离的可视化。讨论了未结合磷酸- lhcii对能量耗散的可能影响。
Plants and green algae maintain efficient photosynthesis under changing light environments by adjusting their light-harvesting capacity. It has been suggested that energy redistribution is brought about by shuttling the light-harvesting antenna complex II (LHCII) between photosystem II (PSII) and photosystem I (PSI) (state transitions), but such molecular remodeling has never been demonstrated in vivo. Here, using chlorophyll fluorescence lifetime imaging microscopy, we visualized phospho-LHCII dissociation from PSII in live cells of the green alga Chlamydomonas reinhardtii. Induction of energy redistribution in wild-type cells led to an increase in, and spreading of, a 250-ps lifetime chlorophyll fluorescence component, which was not observed in the stt7 mutant incapable of state transitions. The 250-ps component was also the dominant component in a mutant containing the light-harvesting antenna complexes but no photosystems. The appearance of the 250-ps component was accompanied by activation of LHCII phosphorylation, supporting the visualization of phospho-LHCII dissociation. Possible implications of the unbound phospho-LHCII on energy dissipation are discussed.