Can red-emitting state be responsible for fluorescence quenching in LHCII aggregates?
Can red-emitting state be responsible for fluorescence quenching in LHCII aggregates?
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DOI：
10.1007/s11120-017-0430-7
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发表时间：
2018-03-01
影响因子：
3.7
通讯作者：
Valkunas, Leonas
中科院分区：
文献类型：
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作者：
Gelzinis, Andrius;Chmeliov, Jevgenij;Valkunas, Leonas
非光化学猝灭（Non-photochemical quenching， NPQ）负责保护植物在强光条件下的光收集装置免受损害。虽然人们一致认为NPQ的主要部分是能量依赖猝灭（qE），起源于光收集天线，但其确切机制仍存在争议。在我们早期的工作中（Chmeliov et al. In Nat Plants 2:160 . 45, 2016），我们分析了植物主要光收集复合物（LHCII）的三聚体和聚集体在宽温度范围内的时间分辨荧光（TRF），并得出结论，需要三种不同的状态来描述实验数据：其中两个态对应于类似680和类似700 nm的发射带，第三个态负责激发猝灭。这与早先提出的双态模型相反，在双态模型中，红移荧光和激发猝灭被认为是相关的。为了检验这种可能性，在当前的工作中，我们根据两态模型重复了我们对后机匣数据的分析。我们发现，尽管它可以合理地描述聚集体荧光，但它不能对LHCII三聚体这样做。我们得出结论，在LHCII聚集体中，红色发射态不能导致荧光猝灭，并重申三态模型是对实验数据最简单的描述。
Non-photochemical quenching (NPQ) is responsible for protecting the light-harvesting apparatus of plants from damage at high light conditions. Although it is agreed that the major part of NPQ, an energy-dependent quenching (qE), originates in the light-harvesting antenna, its exact mechanism is still debated. In our earlier work (Chmeliov et al. in Nat Plants 2:16045, 2016), we have analyzed the time-resolved fluorescence (TRF) from the trimers and aggregates of the major light-harvesting complexes of plants (LHCII) over a broad temperature range and came to a conclusion that three distinct states are required to describe the experimental data: two of them correspond to the emission bands centered at similar to 680 and similar to 700 nm, and the third state is responsible for the excitation quenching. This was opposite to earlier suggestions of a two-state model, where the red-shifted fluorescence and excitation quenching were assumed to be related. To examine such possibility, in the current work we repeat our analysis of the TRF data in terms of the two-state model. We find that even though it can reasonably describe the aggregate fluorescence, it fails to do so for the LHCII trimers. We conclude that the red-emitting state cannot be responsible for fluorescence quenching in the LHCII aggregates and reaffirm that the three-state model is the simplest possible description of the experimental data.