Flavodiiron proteins Flv1 and Flv3 enable cyanobacterial growth and photosynthesis under fluctuating light
Flavodiiron proteins Flv1 and Flv3 enable cyanobacterial growth and photosynthesis under fluctuating light
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DOI：
10.1073/pnas.1221194110
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发表时间：
2013-03-05
影响因子：
11.1
通讯作者：
Aro, Eva-Mari
中科院分区：
文献类型：
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作者：
Allahverdiyeva, Yagut;Mustila, Henna;Aro, Eva-Mari
蓝藻黄素二铁蛋白(FDPs；A型黄素蛋白，FLV)除了含有所有FDP所特有的类β-内酰胺酶和黄素蛋白结构域外，还含有一个额外的NAD(P)H：黄素氧化还原酶模块，因此不同于其他细菌和古生物中的FDP。聚球藻。PCC6803有四个编码FDPs的基因。Flv1和Flv3的功能类似于NAD(P)H：氧氧化还原酶，直接向O-2提供电子，而不产生活性氧物种。在这里，我们证明了Flv1和Flv3蛋白对于蓝藻在波动光下是至关重要的，波动光是水环境中典型的光条件。在恒定光照条件下，无论光照强度如何，Flv1和Flv3蛋白都是必不可少的。相反，在波动光条件下，聚球藻Delta flv1(A)和/或Delta flv3(A)突变体的生长和光合作用。PCC 6803和鱼腥藻(Anabaena sp.)PCC7120被逮捕，在最严重的情况下导致细胞死亡。这种反应主要是由光系统I的故障和在突然的短期光强增加过程中产生的活性氧物种引起的氧化损伤引起的。与缺乏FDPs并使用质子梯度调节5来保护光系统I的高等植物不同，质子梯度调节5的蓝藻同源基因被证明对波动光下的生长不是至关重要的。相反，独特的Flv1/Flv3异二聚体在蓝藻中维持电子转移链的氧化还原平衡，并在波动的生长光下为光系统I提供保护。讨论了独特的蓝藻FDPs的进化是氧合光合作用发展的先决条件。
Cyanobacterial flavodiiron proteins (FDPs; A-type flavoprotein, Flv) comprise, besides the beta-lactamase-like and flavodoxin domains typical for all FDPs, an extra NAD(P)H:flavin oxidoreductase module and thus differ from FDPs in other Bacteria and Archaea. Synechocystis sp. PCC 6803 has four genes encoding the FDPs. Flv1 and Flv3 function as an NAD(P) H: oxygen oxidoreductase, donating electrons directly to O-2 without production of reactive oxygen species. Here we show that the Flv1 and Flv3 proteins are crucial for cyanobacteria under fluctuating light, a typical light condition in aquatic environments. Under constant-light conditions, regardless of light intensity, the Flv1 and Flv3 proteins are dispensable. In contrast, under fluctuating light conditions, the growth and photosynthesis of the Delta flv1(A) and/or Delta flv3(A) mutants of Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120 become arrested, resulting in cell death in the most severe cases. This reaction is mainly caused by malfunction of photosystem I and oxidative damage induced by reactive oxygen species generated during abrupt short-term increases in light intensity. Unlike higher plants that lack the FDPs and use the Proton Gradient Regulation 5 to safeguard photosystem I, the cyanobacterial homolog of Proton Gradient Regulation 5 is shown not to be crucial for growth under fluctuating light. Instead, the unique Flv1/Flv3 heterodimer maintains the redox balance of the electron transfer chain in cyanobacteria and provides protection for photosystem I under fluctuating growth light. Evolution of unique cyanobacterial FDPs is discussed as a prerequisite for the development of oxygenic photosynthesis.