Higher Plant Photosystem II Light-Harvesting Antenna, Not the Reaction Center, Determines the Excited-State Lifetime-Both the Maximum and the Nonphotochemically Quenched
Higher Plant Photosystem II Light-Harvesting Antenna, Not the Reaction Center, Determines the Excited-State Lifetime-Both the Maximum and the Nonphotochemically Quenched
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DOI：
10.1016/j.bpj.2012.05.004
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发表时间：
2012-06-20
影响因子：
3.4
通讯作者：
Ruban, Alexander V.
中科院分区：
文献类型：
--
作者：
Belgio, Erica;Johnson, Matthew P.;Ruban, Alexander V.
孤立光系统II （PSII）光收集复合物（LHCII）天线的最大叶绿素荧光寿命为4 ns；然而，在完整的类囊体膜中，当PSII反应中心（RCIIs）关闭时，它被淬灭到2ns （Fm）。提出了rci的闭合状态是导致淬火的原因。据我们所知，我们使用一种新的模型系统来研究这一建议，在该模型系统中，类囊体膜内RCIIs的浓度高度降低。该系统是在长期使用叶绿体蛋白合成抑制剂林可霉素处理的拟南芥植物中建立的。处理导致1)，rcii浓度降低到对照水平的10%，有趣的是，天线成分增加；2)光化学产率平均降低到0.2；3)非光化学叶绿素荧光猝灭（NPQ）增加。尽管有这些变化，在Fm和Fm'（含NPQ）状态下测量的平均荧光寿命几乎与从对照中获得的相同。处理后的PSII膜的77 K荧光光谱分析显示LHCII的典型预聚集特征，表明LHCII天线在暗适应光合膜中的状态足以决定2 ns Fm寿命。因此，我们得出结论，闭合RCs不会引起PSII天线的激励猝灭，也不会对NPQ的形成起作用。
The maximum chlorophyll fluorescence lifetime in isolated photosystem II (PSII) light-harvesting complex (LHCII) antenna is 4 ns; however, it is quenched to 2 ns in intact thylakoid membranes when PSII reaction centers (RCIIs) are closed (Fm). It has been proposed that the closed state of RCIIs is responsible for the quenching. We investigated this proposal using a new, to our knowledge, model system in which the concentration of RCIIs was highly reduced within the thylakoid membrane. The system was developed in Arabidopsis thaliana plants under long-term treatment with lincomycin, a chloroplast protein synthesis inhibitor. The treatment led to 1), a decreased concentration of RCIIs to 10% of the control level and, interestingly, an increased antenna component; 2), an average reduction in the yield of photochemistry to 0.2; and 3), an increased non-photochemical chlorophyll fluorescence quenching (NPQ). Despite these changes, the average fluorescence lifetimes measured in Fm and Fm' (with NPQ) states were nearly identical to those obtained from the control. A 77 K fluorescence spectrum analysis of treated PSII membranes showed the typical features of preaggregation of LHCII, indicating that the state of LHCII antenna in the dark-adapted photosynthetic membrane is sufficient to determine the 2 ns Fm lifetime. Therefore, we conclude that the closed RCs do not cause quenching of excitation in the PSII antenna, and play no role in the formation of NPQ.