Dark accumulation of downstream glycolytic intermediates initiates robust photosynthesis in cyanobacteria
Dark accumulation of downstream glycolytic intermediates initiates robust photosynthesis in cyanobacteria
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DOI：
10.1093/plphys/kiac602
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发表时间：
2022-12-27
期刊：
影响因子：
7.4
通讯作者：
Hasunuma，Tomohisa
中科院分区：
文献类型：
--
作者：
Tanaka，Kenya;Shirai，Tomokazu;Hasunuma，Tomohisa
光合作用必须在波动的自然环境中保持稳定性和鲁棒性。在蓝藻中，暗-光转换导致了从暗呼吸代谢到CO2固定的剧烈代谢变化，通过Calvin-Benson-Bassham（CBB）循环利用光合电子传递提供的能量和氧化还原当量。以前的研究表明，分解代谢支持平稳过渡到CBB循环代谢。然而，由于缺乏从暗到光转换的动态代谢特征，光合作用的稳健启动的代谢机制知之甚少。在这里，我们显示了快速的动态变化（秒的时间尺度上）绝对代谢物浓度和13 C示踪剂掺入后，在蓝藻Synechocystissp的强光或弱光照射。PCC 6803。这些数据的整合使得能够估计CBB循环激活的时间分辨非平稳代谢通量。这种动态代谢分析表明，下游糖酵解中间体，包括磷酸甘油酸和磷酸烯醇丙酮酸，积累在黑暗条件下作为初始CO2固定的主要底物。与野生型集胞藻相比，在12小时黑暗预孵育缺乏糖原降解或氧化戊糖磷酸途径的突变体中观察到初始析氧速率显着下降。因此，在初始氧释放速率的降低程度是成比例的糖酵解中间体的累积池的大小。这些观察结果表明，糖酵解中间体的积累是必不可少的有效的代谢转换波动的光环境下。
Photosynthesis must maintain stability and robustness throughout fluctuating natural environments. In cyanobacteria, dark-to-light transition leads to drastic metabolic changes from dark respiratory metabolism to CO2fixation through the Calvin–Benson–Bassham (CBB) cycle using energy and redox equivalents provided by photosynthetic electron transfer. Previous studies have shown that catabolic metabolism supports the smooth transition into CBB cycle metabolism. However, metabolic mechanisms for robust initiation of photosynthesis are poorly understood due to lack of dynamic metabolic characterizations of dark-to-light transitions. Here, we show rapid dynamic changes (on a time scale of seconds) in absolute metabolite concentrations and13C tracer incorporation after strong or weak light irradiation in the cyanobacteriumSynechocystissp. PCC 6803. Integration of this data enabled estimation of time-resolved nonstationary metabolic flux underlying CBB cycle activation. This dynamic metabolic analysis indicated that downstream glycolytic intermediates, including phosphoglycerate and phosphoenolpyruvate, accumulate under dark conditions as major substrates for initial CO2fixation. Compared with wild-typeSynechocystis, significant decreases in the initial oxygen evolution rate were observed in 12 h dark preincubated mutants deficient in glycogen degradation or oxidative pentose phosphate pathways. Accordingly, the degree of decrease in the initial oxygen evolution rate was proportional to the accumulated pool size of glycolytic intermediates. These observations indicate that the accumulation of glycolytic intermediates is essential for efficient metabolism switching under fluctuating light environments.