Mechanistic aspects of xanthophyll cycle‐dependent photoprotection in higher plant chloroplasts and leaves
Mechanistic aspects of xanthophyll cycle‐dependent photoprotection in higher plant chloroplasts and leaves
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DOI：
10.1111/j.1399-3054.1997.tb03449.x
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发表时间：
1997
影响因子：
6.4
通讯作者：
A. Gilmore
中科院分区：
文献类型：
--
作者：
A. Gilmore
高等植物必须耗散吸收的超过光合能力的光能，以避免对组成光合机构的色素和蛋白质的分子损伤。在这篇小综述中描述的是目前的生物化学，生物物理学和生物能量方面的主要光保护机制负责消散多余的激发能作为热从光系统II（PSII）。光保护热耗散测量为PSII叶绿素a（Chla）荧光的非光化学猝灭（NPQ）。NPQ机制受跨类囊体膜pH梯度（ΔpH）和特殊的叶黄素循环色素控制。在NPQ机制中，花药黄质（A）和玉米黄质（Z）的脱环氧端基和跨类囊体膜取向强烈影响它们与PSII内触角的质子化叶绿素结合蛋白（CP）的相互作用。CP质子化位点和步骤受到类囊体膜的蛋白质-脂质核心内的质子结构域的影响。叶黄素循环富集周围的CP可以解释为什么在外周PSII天线大小的变化不一定会影响每PSII单位的基础上或NPQ机制的叶黄素循环色素的浓度。最近的时间分辨PSII Chi a荧光研究表明，NPQ机制开关PSII单位增加的热耗散速率常数的一系列步骤，包括叶黄素脱环氧化，CP-质子化和结合的叶黄素质子化的CP;一致的过程可以用一个简单的两步，pH值激活模型来描述。次最佳光合作用温度通过对跨类囊体膜能量耦合系统的影响，对依赖于叶黄素循环的NPQ机制产生深远影响。此外，低温效应可以分为短期（分钟至小时）或长期（天至季节）的PSII色素蛋白的含量和组成的变化系列。这篇小评论的结论是简要强调了关于NPQ机制的未来研究兴趣的主要领域。
Higher plants must dissipate absorbed light energy that exceeds the photosynthetic capacity to avoid molecular damage to the pigments and proteins that comprise the photosynthetic apparatus. Described in this minireview is a current view of the biochemical, biophysical and bioenergetic aspects of the primary photoprotective mechanism responsible for dissipating excess excitation energy as heat from photosystem II (PSII). The photoprotective heat dissipation is measured as nonphotochemical quenching (NPQ) of the PSII chlorophyll a (Chl a) fluorescence. The NPQ mechanism is controlled by the trans-thylakoid membrane pH gradient (ΔpH) and the special xanthophyll cycle pigments. In the NPQ mechanism, the de-epoxidized endgroup moieties and the trans-thylakoid membrane orientations of antheraxanthin (A) and zeaxanthin (Z) strongly affect their interactions with protonated chlorophyll binding proteins (CPs) of the PSII inner antenna. The CP protonation sites and steps are influenced by proton domains sequestered within the proteo-lipid core of the thylakoid membrane. Xanthophyll cycle enrichment around the CPs may explain why changes in the peripheral PSII antenna size do not necessarily affect either the concentration of the xanthophyll cycle pigments on a per PSII unit basis or the NPQ mechanism. Recent time-resolved PSII Chi a fluorescence studies suggest the NPQ mechanism switches PSII units to an increased rate constant of heat dissipation in a series of steps that include xanthophyll de-epoxidation, CP-protonation and binding of the xanthophylls to the protonated CPs; the concerted process can be described with a simple two-step, pH-activation model. The xanthophyll cycle-dependent NPQ mechanism is profoundly influenced by temperatures suboptimal for photosynthesis via their effects on the trans-thylakoid membrane energy coupling system. Further, low temperature effects can be grouped into either short term (minutes to hours) or long term (days to seasonal) series of changes in the content and composition of the PSII pigment-proteins. This minireview concludes by briefly highlighting primary areas of future research interest regarding the NPQ mechanism.