The importance of a highly active and ΔpH-regulated diatoxanthin epoxidase for the regulation of the PSII antenna function in diadinoxanthin cycle containing algae
The importance of a highly active and ΔpH-regulated diatoxanthin epoxidase for the regulation of the PSII antenna function in diadinoxanthin cycle containing algae
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DOI：
10.1016/j.jplph.2005.09.008
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发表时间：
2006-10-01
影响因子：
4.3
通讯作者：
Richter, Michael
中科院分区：
文献类型：
--
作者：
Goss, Reimund;Pinto, Elizabeth Ann;Richter, Michael
本研究重点关注藻类三角褐指藻、假微型海链藻、小环藻和小环藻的二氮黄素（Ddx）循环中二氮黄素（Dtx）环氧化的调节及其对控制光系统11（PS 11）天线功能的意义。我们的数据表明，当藻类细胞从高密度（HL）转移到低密度（LL）时，Dtx环氧酶可以表现出极高的活性。在 HL 条件下，紧驱动质子梯度强烈抑制 Dtx 环氧化。 HL 照明期间细胞的解偶联恢复了 LL 期间观察到的高环氧化速率。在含有藻类的 Ddx 循环中，叶绿素荧光 (NPQ) 的非光化学猝灭与 Dtx 浓度直接相关，并且与质子梯度的存在无关。这意味着PS 11从散热状态快速转换回光收集状态只能通过有效去除淬火颜料Dtx来实现。有人提出，LL 照明期间的高 Dtx 环氧化率正是达到此目的。另一方面，当需要在 HL 照明条件下进行光保护时，Delta pH 对 Dtx 环氧化的抑制可确保 Dtx 浓度快速增加。含有藻类的 Ddx 循环中 PS II 天线功能的调节与含有植物的紫杉素 (Vx) 循环中的 PS II 天线功能的调节不同，其中对于玉米黄质 (Zx) 依赖的 NPQ 来说，质子梯度的存在是强制性的。在绿藻普通小球藻中，PS 11 从散热状态返回到光捕获状态的转换是由 Delta pH 控制的，从 HL 过渡到黑暗或 LL 后，其弛豫迅速消除了激发能的热耗散，包括 Zx 依赖性 NPQ。由于 Zx 在没有 Delta pH 的情况下无法淬灭荧光，因此不需要 LL 中 Zx 快速环氧化为 Vx，并且在小球藻中这种情况是缺失的。 (c) 2005 年爱思唯尔有限公司。版权所有。
The present study focuses on the regulation of diatoxanthin (Dtx) epoxidation in the diadinoxanthin (Ddx) cycle containing algae Phaeodactylum tricornutum, Thalassiosira pseudonana, Cyclotello meneghiniana and Prymnesium parvum and its significance for the control of the photosystem 11 (PS 11) antenna function. Our data show that Dtx epoxidase can exhibit extremely high activities when algal cells are transferred from high tight (HL) to tow light (LL). Under HL conditions, Dtx epoxidation is strongly inhibited by the tight-driven proton gradient. Uncoupling of the cells during HL illumination restores the high epoxidation rates observed during LL. In Ddx cycle containing algae, non-photochemical quenching of chlorophyll fluorescence (NPQ) is directly correlated with the Dtx concentration and independent of the presence of the proton gradient. This means that a fast conversion of PS 11 from the heat dissipating state back to the light-harvesting state can only be realized by an efficient removal of the quenching pigment Dtx. It is proposed that the high Dtx epoxidation rates during LL illumination serve exactly this purpose. The inhibition of Dtx epoxidation by the Delta pH, on the other hand, ensures rapid increases in the Dtx concentration when photoprotection under conditions of HL illumination is required. The regulation of the PS II antenna function in Ddx cycle containing algae is different to that in viotaxanthin (Vx) cycle containing plants, where for the zeaxanthin (Zx)-dependent NPQ the presence of a proton gradient is mandatory. In the green alga Chlorella vulgaris conversion of PS 11 from the heat dissipating state back to the light-harvesting state is controlled by the Delta pH, whose relaxation after a transition from HL to darkness or LL rapidly abolishes the thermal dissipation of excitation energy, including the Zx-dependent NPQ. Due to the inability of Zx to quench fluorescence in the absence of the Delta pH a fast epoxidation of Zx to Vx in LL is not needed and is missing in Chlorella vulgaris. (c) 2005 Elsevier GmbH. All rights reserved.