Overexpression of bifunctional fructose-1,6-bisphosphatase/sedoheptulose-1,7-bisphosphatase leads to enhanced photosynthesis and global reprogramming of carbon metabolism in Synechococcus sp PCC 7002
Overexpression of bifunctional fructose-1,6-bisphosphatase/sedoheptulose-1,7-bisphosphatase leads to enhanced photosynthesis and global reprogramming of carbon metabolism in Synechococcus sp PCC 7002
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DOI：
10.1016/j.ymben.2018.03.001
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发表时间：
2018-05-01
影响因子：
8.4
通讯作者：
Sakuragi, Yumiko
中科院分区：
文献类型：
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作者：
De Porcellinis, Alice Jara;Norgaard, Hanne;Sakuragi, Yumiko
蓝细菌将大气中的二氧化碳固定到生物质中，并通过代谢工程也可以作为光合作用工厂，用于可持续生产燃料和化学品。卡尔文本森循环是蓝藻、藻类和C-3植物固定CO2的主要途径。先前的研究已经在植物和藻类中过表达了卡尔文本森循环酶、核酮糖-1，5-二磷酸羧化酶/加氧酶（RuBisCO）和双功能景天庚酮糖-1，7-二磷酸酶/果糖-1，6-二磷酸酶（以下简称BiBPase），尽管它们对蓝藻的影响尚未被严格研究。在这里，我们表明，过表达的BiBP酶和RuBisCO有不同的影响，在蓝藻聚球藻属PCC 7002通过生理，生化和蛋白质组学分析的碳代谢。前者增强生长、细胞大小和光合O-2进化，并协同上调卡尔文本森循环中的酶，包括RuBisCO和果糖-1，6-二磷酸醛缩酶。同时，它下调呼吸碳代谢（糖酵解和氧化戊糖磷酸途径）中的酶，包括葡萄糖-6-磷酸脱氢酶（G6 PDH）。糖原含量也显著降低，而可溶性糖含量增加。这些结果表明，BiBP酶的过表达导致聚球藻属PCC 7002中碳代谢的全局重编程，促进光合碳固定和碳向非储存碳水化合物的分配。相反，虽然RuBisCO的过度表达对生长和光合O-2进化没有可测量的影响，但它导致丙酮酸代谢和脂肪酸生物合成中涉及的蛋白质丰度的协调增加。我们的研究结果证实，卡尔文本森周期中的单一遗传修饰可以产生比以前预期的更广泛的细胞影响。这些特征可以被利用来更有效地将碳导向所需的生物产品。
Cyanobacteria fix atmospheric CO2 to biomass and through metabolic engineering can also act as photosynthetic factories for sustainable productions of fuels and chemicals. The Calvin Benson cycle is the primary pathway for CO2 fixation in cyanobacteria, algae and C-3 plants. Previous studies have overexpressed the Calvin Benson cycle enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and bifunctional sedoheptulose-1,7-bisphosphatase/fructose-1,6-bisphosphatase (hereafter BiBPase), in both plants and algae, although their impacts on cyanobacteria have not yet been rigorously studied. Here, we show that overexpression of BiBPase and RuBisCO have distinct impacts on carbon metabolism in the cyanobacterium Synechococcus sp. PCC 7002 through physiological, biochemical, and proteomic analyses. The former enhanced growth, cell size, and photosynthetic O-2 evolution, and coordinately upregulated enzymes in the Calvin Benson cycle including RuBisCO and fructose-1,6-bisphosphate aldolase. At the same time it downregulated enzymes in respiratory carbon metabolism (glycolysis and the oxidative pentose phosphate pathway) including glucose-6-phosphate dehydrogenase (G6PDH). The content of glycogen was also significantly reduced while the soluble carbohydrate content increased. These results indicate that overexpression of BiBPase leads to global reprogramming of carbon metabolism in Synechococcus sp. PCC 7002, promoting photosynthetic carbon fixation and carbon partitioning towards non-storage carbohydrates. In contrast, whilst overexpression of RuBisCO had no measurable impact on growth and photosynthetic O-2 evolution, it led to coordinated increase in the abundance of proteins involved in pyruvate metabolism and fatty acid biosynthesis. Our results underpin that singular genetic modifications in the Calvin Benson cycle can have far broader cellular impact than previously expected. These features could be exploited to more efficiently direct carbons towards desired bioproducts.