Restoration of Rapidly Reversible Photoprotective Energy Dissipation in the Absence of PsbS Protein by Enhanced ΔpH
Restoration of Rapidly Reversible Photoprotective Energy Dissipation in the Absence of PsbS Protein by Enhanced ΔpH
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DOI：
10.1074/jbc.m111.237255
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发表时间：
2011-06-03
影响因子：
4.8
通讯作者：
Ruban, Alexander V.
中科院分区：
文献类型：
--
作者：
Johnson, Matthew P.;Ruban, Alexander V.
光环境的变化需要高等植物调节光收集过程。在强光下，一种被称为非光化学猝灭（NPQ）的机制被触发，以热量的形式消散光系统II （PSII）天线内多余的吸收光能，防止对反应中心的光损伤。NPQ的主要成分，被称为qE，在黑暗中是快速可逆的，并且依赖于光合电子传递形成的跨膜质子梯度（δ pH）。利用二氨基durene和phenazine metasulate这两种光系统I周围循环电子流动的介质来提高Delta pH值，研究表明，在缺乏PsbS蛋白的拟南芥完整叶绿体中可以观察到快速可逆的q型猝灭，而PsbS蛋白在这一过程中是必不可少的。缺乏PsbS的叶绿体中的qE显著猝灭了所有PSII反应中心处于开放状态（F-o态）时的荧光水平，保护了PSII反应中心免受光抑制，并由玉米黄质调节，并伴有qE典型的吸收光谱变化，称为Delta A（535）。在没有PsbS的情况下，qE的δ pH依赖性的滴定表明，该蛋白影响了光保护过程对质子的协同性和敏感性。本文讨论了PsbS和玉米黄质通过调控PSII天线重组/聚集和疏水性的相互关联现象，参与控制质子-天线关联常数pK的作用。
Variations in the light environment require higher plants to regulate the light harvesting process. Under high light a mechanism known as non-photochemical quenching (NPQ) is triggered to dissipate excess absorbed light energy within the photosystem II (PSII) antenna as heat, preventing photodamage to the reaction center. The major component of NPQ, known as qE, is rapidly reversible in the dark and dependent upon the transmembrane proton gradient (Delta pH), formed as a result of photosynthetic electron transport. Using diaminodurene and phenazine metasulfate, mediators of cyclic electron flow around photosystem I, to enhance Delta pH, it is demonstrated that rapidly reversible qE-type quenching can be observed in intact chloroplasts from Arabidopsis plants lacking the PsbS protein, previously believed to be indispensible for the process. The qE in chloroplasts lacking PsbS significantly quenched the level of fluorescence when all PSII reaction centers were in the open state (F-o state), protected PSII reaction centers from photoinhibition, was modulated by zeaxanthin and was accompanied by the qE-typical absorption spectral changes, known as Delta A(535). Titrations of the Delta pH dependence of qE in the absence of PsbS reveal that this protein affects the cooperativity and sensitivity of the photoprotective process to protons. The roles of PsbS and zeaxanthin are discussed in light of their involvement in the control of the proton-antenna association constant, pK, via regulation of the interconnected phenomena of PSII antenna reorganization/aggregation and hydrophobicity.