Nakajima Tsubasa, Kajihata Shuichi, Yoshikawa Katsunori, Matsuda Fumio, Furusawa Chikara, Hirasawa Takashi, Shimizu Hiroshi
Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871 Japan Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (JST, CREST).
Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871 Japan Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (JST, CREST) Quantitative Biology Center (QBiC), RIKEN, 6-2-3 Furuedai, Suita, Osaka, 565-0874 Japan.
Plant Cell Physiol. 2014 Sep;55(9):1605-12. doi: 10.1093/pcp/pcu091. Epub 2014 Jun 26.
Cyanobacteria have flexible metabolic capability that enables them to adapt to various environments. To investigate their underlying metabolic regulation mechanisms, we performed an integrated analysis of metabolic flux using transcriptomic and metabolomic data of a cyanobacterium Synechocystis sp. PCC 6803, under mixotrophic and photoheterotrophic conditions. The integrated analysis indicated drastic metabolic flux changes, with much smaller changes in gene expression levels and metabolite concentrations between the conditions, suggesting that the flux change was not caused mainly by the expression levels of the corresponding genes. Under photoheterotrophic conditions, created by the addition of the photosynthesis inhibitor atrazine in mixotrophic conditions, the result of metabolic flux analysis indicated the significant repression of carbon fixation and the activation of the oxidative pentose phosphate pathway (PPP). Moreover, we observed gluconeogenic activity of upstream of glycolysis, which enhanced the flux of the oxidative PPP to compensate for NADPH depletion due to the inhibition of the light reaction of photosynthesis. 'Omics' data suggested that these changes were probably caused by the repression of the gap1 gene, which functions as a control valve in the metabolic network. Since metabolic flux is the outcome of a complicated interplay of cellular components, integrating metabolic flux with other 'omics' layers can identify metabolic changes and narrow down these regulatory mechanisms more effectively.
蓝藻具有灵活的代谢能力，使其能够适应各种环境。为了研究其潜在的代谢调控机制，我们利用蓝藻聚球藻属PCC 6803在混合营养和光异养条件下的转录组和代谢组数据，对代谢通量进行了综合分析。综合分析表明代谢通量发生了剧烈变化，而不同条件下基因表达水平和代谢物浓度的变化要小得多，这表明通量变化并非主要由相应基因的表达水平引起。在混合营养条件下添加光合作用抑制剂莠去津所创造的光异养条件下，代谢通量分析结果表明碳固定受到显著抑制，氧化戊糖磷酸途径（PPP）被激活。此外，我们观察到糖酵解上游的糖异生活性，这增强了氧化PPP的通量，以补偿由于光合作用光反应受抑制而导致的NADPH消耗。“组学”数据表明，这些变化可能是由gap1基因的抑制引起的，该基因在代谢网络中起控制阀的作用。由于代谢通量是细胞成分复杂相互作用的结果，将代谢通量与其他“组学”层面整合可以识别代谢变化，并更有效地缩小这些调控机制的范围。
