You Xiuqi, Chen Ximin, Jiang Yi, Chen Huan, Liu Juan, Wu Zhen, Sun Weiling, Ni Jinren
Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
State Environmental Protection Key Laboratory of All Material Fluxes in River Ecosystems, Beijing 100871, China.
Innovation (Camb). 2024 Apr 26;5(4):100630. doi: 10.1016/j.xinn.2024.100630. eCollection 2024 Jul 1.
Photosynthetic carbon fixation by cyanobacteria plays a pivotal role in the global carbon cycle but is threatened by environmental pollutants. To date, the impact of quinones, with electron shuttling properties, on cyanobacterial photosynthesis is unknown. Here, we present the first study investigating the effects of an emerging quinone pollutant, i.e., 6PPD-Q (N-(1,3-dimethylbutyl)-N'-phenyl--phenylenediamine-quinone), on the cyanobacterium sp. over a 400-generation exposure period. sp. exhibited distinct sequential phases, including hormesis, toxicity, and eventual recovery, throughout this exposure. Extensive evidence, including results of thylakoid membrane morphological and photosynthetic responses, carbon fixation rate, and key gene/protein analyses, strongly indicates that 6PPD-Q is a potent disruptor of photosynthesis. 6PPD-Q accepts photosynthetic electrons at the plastoquinone Q site in photosystem II (PSII) and the phylloquinone A site in PSI, leading to a sustained decrease in the carbon fixation of cyanobacteria after an ephemeral increase. This work revealed the specific mechanism by which 6PPD-Q interferes with photosynthetic carbon fixation in cyanobacteria, which is highly important for the global carbon cycle.
蓝藻的光合碳固定在全球碳循环中起着关键作用，但受到环境污染物的威胁。迄今为止，具有电子穿梭特性的醌类物质对蓝藻光合作用的影响尚不清楚。在此，我们首次开展研究，考察一种新兴的醌类污染物，即6PPD-Q（N-(1,3-二甲基丁基)-N'-苯基-对苯二胺-醌）在400代暴露期内对蓝藻的影响。在整个暴露过程中，蓝藻呈现出不同的连续阶段，包括兴奋效应、毒性作用以及最终的恢复。大量证据，包括类囊体膜形态和光合反应结果、碳固定率以及关键基因/蛋白质分析，有力地表明6PPD-Q是光合作用的强效破坏剂。6PPD-Q在光系统II（PSII）的质体醌Q位点和光系统I（PSI）的叶绿醌A位点接受光合电子，导致蓝藻碳固定在短暂增加后持续下降。这项工作揭示了6PPD-Q干扰蓝藻光合碳固定的具体机制，这对全球碳循环非常重要。
