Alternative photosynthesis pathways drive the algal CO2-concentrating mechanism
Alternative photosynthesis pathways drive the algal CO2-concentrating mechanism
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DOI：
10.1038/s41586-022-04662-9
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发表时间：
2022-05-12
期刊：
影响因子：
64.8
通讯作者：
Peltier, Gilles
中科院分区：
文献类型：
--
作者：
Burlacot, Adrien;Dao, Ousmane;Peltier, Gilles
全球光合作用消耗的二氧化碳是净人为排放量的十倍，微藻占这一消耗量的近一半（1）。藻类光合作用的高效率依赖于在羧化酶RuBisCO的催化位点浓缩CO2（CCM）的机制，这增强了CO2固定（2）。尽管已经鉴定了许多参与无机碳的运输和封存的细胞组分（3，4），但微藻如何供应能量以克服热力学梯度浓缩CO2仍然是未知的（4-6）。在这里，我们表明，在绿色衣藻莱茵衣藻，循环电子流和O-2光还原的联合行动，这取决于PGRL 1和flavodiiron蛋白，分别产生一个低的管腔pH值是必不可少的CCM功能。我们认为，腔质子下游的类囊体雌激素样转运蛋白，可能是碳酸氢盐的转换为CO2。我们进一步确定，从叶绿体到线粒体的电子流有助于激励非类囊体无机碳转运蛋白，可能是通过提供ATP。我们提出了一个综合的网络供应能量的CCM的观点，并描述了藻类细胞如何分配能量从光合作用，以不同的CCM过程的电源。这些结果表明了一种将功能性藻类CCM转移到植物中以提高作物产量的途径。
Global photosynthesis consumes ten times more CO2 than net anthropogenic emissions, and microalgae account for nearly half of this consumption(1). The high efficiency of algal photosynthesis relies on a mechanism concentrating CO2 (CCM) at the catalytic site of the carboxylating enzyme RuBisCO, which enhances CO2 fixation(2). Although many cellular components involved in the transport and sequestration of inorganic carbon have been identified(3,4), how microalgae supply energy to concentrate CO2 against a thermodynamic gradient remains unknown(4-6). Here we show that in the green alga Chlamydomonas reinhardtii, the combined action of cyclic electron flow and O-2 photoreduction-which depend on PGRL1 and flavodiiron proteins, respectively-generate a low luminal pH that is essential for CCM function. We suggest that luminal protons are used downstream of thylakoid bestrophin-like transporters, probably for the conversion of bicarbonate to CO2. We further establish that an electron flow from chloroplast to mitochondria contributes to energizing non-thylakoid inorganic carbon transporters, probably by supplying ATP. We propose an integrated view of the network supplying energy to the CCM, and describe how algal cells distribute energy from photosynthesis to power different CCM processes. These results suggest a route for the transfer of a functional algal CCM to plants to improve crop productivity.