Integrated flux and pool size analysis in plant central metabolism reveals unique roles of glycine and serine during photorespiration
Integrated flux and pool size analysis in plant central metabolism reveals unique roles of glycine and serine during photorespiration
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DOI：
10.1038/s41477-022-01294-9
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发表时间：
2022-12-19
期刊：
影响因子：
18
通讯作者：
Walker, Berkley J.
中科院分区：
文献类型：
--
作者：
Fu, Xinyu;Gregory, Luke M.;Walker, Berkley J.
光呼吸是植物响应动态环境的一个重要的碳氮代谢过程。光呼吸作用将Rubisco催化的氧化反应产生的抑制性中间体重新释放到C-3循环中，但目前尚不清楚其含氮中间体（甘氨酸和丝氨酸）在体内被输出到其他代谢中的比例，以及这些池的大小如何影响光呼吸瞬变过程中的净CO2气体交换。在这里，为了解决这种不确定性，我们测量的氨基酸出口率从光呼吸使用同位素非稳态代谢通量分析。该分析显示，在各种光呼吸条件下，类似于23-41%的光呼吸碳以丝氨酸的形式从该途径输出。此外，我们确定了甘氨酸池的建立和放松限制了光呼吸瞬变过程中的大部分光合驯化。这些结果揭示了甘氨酸和丝氨酸在成功维持自然界环境波动下发生的各种光呼吸通量并为代谢提供碳和氮方面的独特而重要的作用。
Photorespiration is an essential process juxtaposed between plant carbon and nitrogen metabolism that responds to dynamic environments. Photorespiration recycles inhibitory intermediates arising from oxygenation reactions catalysed by Rubisco back into the C-3 cycle, but it is unclear what proportions of its nitrogen-containing intermediates (glycine and serine) are exported into other metabolisms in vivo and how these pool sizes affect net CO2 gas exchange during photorespiratory transients. Here, to address this uncertainty, we measured rates of amino acid export from photorespiration using isotopically non-stationary metabolic flux analysis. This analysis revealed that similar to 23-41% of the photorespiratory carbon was exported from the pathway as serine under various photorespiratory conditions. Furthermore, we determined that the build-up and relaxation of glycine pools constrained a large portion of photosynthetic acclimation during photorespiratory transients. These results reveal the unique and important roles of glycine and serine in successfully maintaining various photorespiratory fluxes that occur under environmental fluctuations in nature and providing carbon and nitrogen for metabolism.