A blue-light photoreceptor mediates the feedback regulation of photosynthesis
A blue-light photoreceptor mediates the feedback regulation of photosynthesis
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DOI：
10.1038/nature19358
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发表时间：
2016-09-22
期刊：
影响因子：
64.8
通讯作者：
Minagawa, Jun
中科院分区：
文献类型：
--
作者：
Petroutsos, Dimitris;Tokutsu, Ryutaro;Minagawa, Jun
在植物和藻类中，光既是光合作用的能量来源，也是通过特定的感觉光感受器触发细胞反应的生物信号。红光由含有十亿素的光敏色素感知，蓝光由含有黄素的隐色素和光促性蛋白（PHOTs）感知(1)，后者含有两个光感光、氧或电压（LOV）域2。光觉跨越几个数量级的光强(3)，范围从远低于光合作用的阈值到超过光合作用CO2同化能力的值。过量的光可能导致氧化损伤和细胞死亡，这一过程可以通过高能猝灭（qE）来增强热耗散，这是一种关键的光保护反应(4)。在这里，我们展示了莱茵衣藻中存在的光接受、光合作用和光保护之间的分子联系。我们发现，PHOT通过在高光强下诱导qE效应蛋白LHCSR3（光收获复合应力相关蛋白3）的表达来控制qE。这种控制需要通过PHOT上的LOV结构域感知蓝光，通过PHOT激酶诱导LHCSR3，以及通过LHCSR3在光系统II中耗散光。缺乏PHOT基因的突变体在过度光照条件下表现出严重的适应度降低，这表明光的感知、利用和耗散是一个协调一致的过程，在微藻适应可变光强环境中起着至关重要的作用。
In plants and algae, light serves both as the energy source for photosynthesis and a biological signal that triggers cellular responses via specific sensory photoreceptors. Red light is perceived by bilin-containing phytochromes and blue light by the flavincontaining cryptochromes and/or phototropins (PHOTs)(1), the latter containing two photosensory light, oxygen, or voltage (LOV) domains2. Photoperception spans several orders of light intensity(3), ranging from far below the threshold for photosynthesis to values beyond the capacity of photosynthetic CO2 assimilation. Excess light may cause oxidative damage and cell death, processes prevented by enhanced thermal dissipation via high-energy quenching (qE), a key photoprotective response(4). Here we show the existence of a molecular link between photoreception, photosynthesis, and photoprotection in the green alga Chlamydomonas reinhardtii. We show that PHOT controls qE by inducing the expression of the qE effector protein LHCSR3 (light-harvesting complex stress-related protein 3) in high light intensities. This control requires blue-light perception by LOV domains on PHOT, LHCSR3 induction through PHOT kinase, and light dissipation in photosystem II via LHCSR3. Mutants deficient in the PHOT gene display severely reduced fitness under excessive light conditions, indicating that the sensing, utilization, and dissipation of light is a concerted process that plays a vital role in microalgal acclimation to environments of variable light intensities.