Metabolome Phenotyping of Inorganic Carbon Limitation in Cells of the Wild Type and Photorespiratory Mutants of the Cyanobacterium Synechocystis sp Strain PCC 6803
Metabolome Phenotyping of Inorganic Carbon Limitation in Cells of the Wild Type and Photorespiratory Mutants of the Cyanobacterium Synechocystis sp Strain PCC 6803
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DOI：
10.1104/pp.108.129403
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发表时间：
2008-12-01
期刊：
影响因子：
7.4
通讯作者：
Hagemann, Martin
中科院分区：
文献类型：
--
作者：
Eisenhut, Marion;Huege, Jan;Hagemann, Martin
无机碳的含量是决定光合自养生物生产力的主要环境因素之一。使用模型蓝藻集胞藻属PCC 6803，我们进行了第一代谢组学研究与蓝藻细胞从高CO2（5%的空气）转移到低CO2的条件下（LC;环境空气与0.035%CO2）。使用气相色谱-质谱法，74代谢产物在不同的生长条件下进行了重复性鉴定。将野生型细胞转移到LC条件下导致全局代谢重编程，并涉及例如2-酮戊二酸（2 OG）和磷酸烯醇丙酮酸的增加，以及例如蔗糖和果糖-1，6-二磷酸的减少。富马酸盐、苹果酸盐和2-磷酸乙醇酸盐池的协同蓄积和3-磷酸甘油酸盐的一过性增加表明Calvin-Benson循环活性降低和相关碳循环途径（包括光呼吸代谢）的使用增加。当细胞面临LC时，2 OG的意外积累伴随着谷氨酰胺的减少指向氮的可用性降低。尽管在2 OG和低氨基酸池的增加，我们发现了一个完整的去磷酸化的PII调节蛋白在LC特征的氮充满条件。此外，在光呼吸代谢中具有确定的阻断的突变体分别导致乙醇酸和甘氨酸的积累，表现出LC处理的野生型细胞的特征，例如在高CO2条件下已经改变的2 OG与谷氨酰胺的比率和PII磷酸化状态。因此，代谢组分析表明，适应LC涉及协调变化的碳和相互作用的氮代谢。我们推测，集胞藻有一个时间滞后的适应碳与碳领先的氮代谢。
The amount of inorganic carbon represents one of the main environmental factors determining productivity of photoautotrophic organisms. Using the model cyanobacterium Synechocystis sp. PCC 6803, we performed a first metabolome study with cyanobacterial cells shifted from high CO2 (5% in air) into conditions of low CO2 (LC; ambient air with 0.035% CO2). Using gas chromatography-mass spectrometry, 74 metabolites were reproducibly identified under different growth conditions. Shifting wild-type cells into LC conditions resulted in a global metabolic reprogramming and involved increases of, for example, 2-oxoglutarate (2OG) and phosphoenolpyruvate, and reductions of, for example, sucrose and fructose-1,6-bisphosphate. A decrease in Calvin-Benson cycle activity and increased usage of associated carbon cycling routes, including photorespiratory metabolism, was indicated by synergistic accumulation of the fumarate, malate, and 2- phosphoglycolate pools and a transient increase of 3-phosphoglycerate. The unexpected accumulation of 2OG with a concomitant decrease of glutamine pointed toward reduced nitrogen availability when cells are confronted with LC. Despite the increase in 2OG and low amino acid pools, we found a complete dephosphorylation of the PII regulatory protein at LC characteristic for nitrogen-replete conditions. Moreover, mutants with defined blocks in the photorespiratory metabolism leading to the accumulation of glycolate and glycine, respectively, exhibited features of LC-treated wild-type cells such as the changed 2OG to glutamine ratio and PII phosphorylation state already under high CO2 conditions. Thus, metabolome profiling demonstrated that acclimation to LC involves coordinated changes of carbon and interacting nitrogen metabolism. We hypothesize that Synechocystis has a temporal lag of acclimating carbon versus nitrogen metabolism with carbon leading.