Characterization of wave phenomena in the relaxation of flash-induced chlorophyll fluorescence yield in cyanobacteria
Characterization of wave phenomena in the relaxation of flash-induced chlorophyll fluorescence yield in cyanobacteria
复制标题
DOI：
10.1016/j.bbabio.2014.01.003
复制
发表时间：
2014-09-01
影响因子：
4.3
通讯作者：
Vass, Imre
中科院分区：
文献类型：
--
作者：
Deak, Zsuzsanna;Sass, Laszlo;Vass, Imre
在有氧和微需氧条件下研究了各种蓝细菌中光脉冲后的荧光产量弛豫。在集胞藻 PCC 6803 中，荧光产量在有氧条件下以单调方式衰减。然而，在微氧条件下，衰减呈现出波形特征，在闪光后 30-50 毫秒处出现下降，随后短暂上升，在大约 1 秒时达到最大值，然后衰减回到初始水平。在有氧条件下，在用连续光预照射的细胞中也可以观察到波动现象。光照使细胞短暂地适应波现象：在集胞藻 PCC 6803 中为几秒钟，但在嗜热集胞藻 BP-1 中长达一小时。分别用 3-(3',4'-二氯苯基)-1,1-二甲基脲或 2,5-二溴-3-甲基-6-异丙基-对苯醌抑制质体醌与光系统-II 的 Q(B) 位点或细胞色素 b(6)f 复合物的 Q(O) 位点的结合，从而消除该波。这种波在缺乏光系统-I 或 NAD(P)H-醌氧化还原酶 (NDH-1) 复合物的突变体中也不存在。监测质体醌池的氧化还原状态表明，荧光波的下降对应于瞬时氧化，而随后的上升对应于质体醌池的重新还原。结论是，荧光产量弛豫的不寻常波特征反映了光系统-I对高度还原的质体醌库的瞬时氧化，然后通过NDH-1复合物从基质成分中重新还原，通过电荷平衡将其传输回荧光产量调节剂初级醌电子受体。讨论了波现象在研究光合作用和呼吸电子传递中的潜在应用。本文是题为“光合作用可持续发展研究：生产清洁能源的关键”特刊的一部分。 (C) 2014 Elsevier B.V. 保留所有权利。
Fluorescence yield relaxation following a light pulse was studied in various cyanobacteria under aerobic and microaerobic conditions. In Synechocystis PCC 6803 fluorescence yield decays in a monotonous fashion under aerobic conditions. However, under microaerobic conditions the decay exhibits a wave feature showing a dip at 30-50 ms after the flash followed by a transient rise, reaching maximum at similar to 1 s, before decaying back to the initial level. The wave phenomenon can also be observed under aerobic conditions in cells preilluminated with continuous light. Illumination preconditions cells for the wave phenomenon transiently: for few seconds in Synechocystis PCC 6803, but up to one hour in Thermosynechocystis elongatus BP-1. The wave is eliminated by inhibition of plastoquinone binding either to the Q(B) site of Photosystem-II or the Q(O) site of cytochrome b(6)f complex by 3-(3',4'-dichlorophenyl)-1,1-dimethylurea or 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, respectively. The wave is also absent in mutants, which lack either Photosystem-I or the NAD(P)H-quinone oxidoreductase (NDH-1) complex. Monitoring the redox state of the plastoquinone pool revealed that the dip of the fluorescence wave corresponds to transient oxidation, whereas the following rise to re-reduction of the plastoquinone pool. It is concluded that the unusual wave feature of fluorescence yield relaxation reflects transient oxidation of highly reduced plastoquinone pool by Photosystem-I followed by its re-reduction from stromal components via the NDH-1 complex, which is transmitted back to the fluorescence yield modulator primary quinone electron acceptor via charge equilibria. Potential applications of the wave phenomenon in studying photosynthetic and respiratory electron transport are discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy. (C) 2014 Elsevier B.V. All rights reserved.