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首页> 美国卫生研究院文献>The Journal of Biological Chemistry >Induction of Efficient Energy Dissipation in the Isolated Light-harvesting Complex of Photosystem II in the Absence of Protein Aggregation
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Induction of Efficient Energy Dissipation in the Isolated Light-harvesting Complex of Photosystem II in the Absence of Protein Aggregation

机译：在隔离中诱导有效的能量消散 缺少蛋白质的光系统II的光收集复合体 聚合

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Under excess illumination, the Photosystem II light-harvesting antenna of higher plants has the ability to switch into an efficient photoprotective mode, allowing safe dissipation of excitation energy into heat. In this study, we show induction of the energy dissipation state, monitored by chlorophyll fluorescence quenching, in the isolated major light-harvesting complex (LHCII) incorporated into a solid gel system. Removal of detergent caused strong fluorescence quenching, which was totally reversible. Singlet-singlet annihilation and gel electrophoresis experiments suggested that the quenched complexes were in the trimeric not aggregated state. Both the formation and recovery of this quenching state were inhibited by a cross-linker, implying involvement of conformational changes. Absorption and CD measurements performed on the samples in the quenched state revealed specific alterations in the spectral bands assigned to the red forms of chlorophyll a, neoxanthin, and lutein 1 molecules. The majority of these alterations were similar to those observed during LHCII aggregation. This suggests that not the aggregation process as such but rather an intrinsic conformational transition in the complex is responsible for establishment of quenching. 77 K fluorescence measurements showed red-shifted chlorophyll a fluorescence in the 690-705 nm region, previously observed in aggregated LHCII. The fact that all spectral changes associated with the dissipative mode observed in the gel were different from those of the partially denatured complex strongly argues against the involvement of protein denaturation in the observed quenching. The implications of these findings for proposed mechanisms of energy dissipation in the Photosystem II antenna are discussed.
机译：在过量照明下，高等植物的Photosystem II光收集天线具有切换到有效光保护模式的能力，从而可以将激发能量安全地散发到热量中。在这项研究中，我们显示了引入到固体凝胶系统中的孤立的主要采光复合物（LHCII）中，通过叶绿素荧光猝灭监测的能量消散状态的诱导。去除洗涤剂会导致强烈的荧光猝灭，这是完全可逆的。单重态单ing灭和凝胶电泳实验表明，淬灭的配合物处于三聚体而不是聚集状态。该猝灭状态的形​​成和恢复均被交联剂抑制，这暗示了构象变化的参与。在淬灭状态下对样品进行的吸收和CD测量表明，分配给红色形式的叶绿素a，新黄嘌呤和叶黄素1分子的光谱带发生了特定变化。这些变化中的大多数与LHCII聚集过程中观察到的相似。这表明不是这种聚集过程，而是复合物中的固有构象转变负责淬灭的建立。 77千 荧光测量显示红移的叶绿素a 690-705 nm区域的荧光，以前在聚合中观察到 LHCII。所有频谱变化都与耗散模式有关的事实 凝胶中观察到的与部分变性的凝胶不同 复合体强烈反对蛋白质变性参与 观察到淬火。这些发现对拟议机制的影响 讨论了Photosystem II天线的能量耗散。

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