本研究文采用集胞藻PCC6803野生型藻株和Slr0643敲除突变体（Δslr0643）藻株，通过生理实验和基于气相色谱-质谱联用 （GC-MS）技术的植物代谢组学分析，对Slr0643蛋白调控集胞藻PCC6803葡萄糖混养适应的机制进行探讨。在2.5 mM葡萄糖混养条件下，野生型藻株的生长速率较光自养条件明显加快，而Δslr0643藻株的生长速率较光自养条件显著下降，在添加葡萄糖其混养培养4 d后的OD730值仅为野生型藻株的47.25%，且其利用葡萄糖的速率也始终低于野生型藻株。通过对野生型藻株和Δslr0643藻株在2.5 mM葡萄糖混养过程中细胞内代谢物进行鉴定，发现了显著差异代谢物各11种，其中，有9种差异代谢物在野生型藻株混养过程中含量明显上升。通过对各时间点下突变体相对于野生型的差异代谢物所参与的代谢通路进行富集分析发现，差异代谢物主要富集在三羧酸循环、丙酮酸代谢、谷氨酸代谢等8个代谢途径，表明Slr0643通过参与调控这些代谢途径使集胞藻PCC6803适应葡萄糖混养。本研究发现了slr0643的缺失使细胞内多种代谢途径受损，从而使细胞无法正常利用葡萄糖，揭示了Slr0643蛋白在集胞藻葡萄糖混养适应中扮演着重要的作用。

In this study, a wild-type strain of Synechocystis sp. PCC6803 and a Slr0643 knockout mutant (Δslr0643) strain were used. The mechanism underlying the regulatory role of Slr0643 protein in the acclimation of Synechocystis sp. PCC6803 to glucose mixotrophic conditions was investigated through physiological experiments and gas chromatography-mass spectrometry (GC-MS)-based plant metabolomic analysis. Under mixotrophic conditions with 2.5 mM glucose, the growth rate of the wild-type was significantly higher than that under autotrophic condition, while the growth rate of Δslr0643 strain was significantly lower than that under autotrophic condition. After four days of mixotrophic growth with glucose, the OD730 value of Δslr0643 mutant was only 47.25% of that for the wild type, and the glucose utilization rate of Δslr0643 mutant was consistently lower than that the wild-type strain. Through the identification of the differential metabolites of the Δslr0643 mutant strain and wild-type strain over the mixotrophic cultivation with 2.5 mM glucose, 11 significantly different metabolites were found, with the contents of 9 differential metabolites in the wild-type strain increasing significantly during mixotrophic cultivation. Through the enrichment analysis of the metabolic pathways involved in the different metabolites of the mutant strain relative to the wild -type strain at each culture time point, it was found that the differential metabolites were mainly enriched in 8 metabolic pathways, the tricarboxylic acid cycle, pyruvate metabolism, glutamate metabolism, suggesting that Slr0643 protein was involved in regulating these metabolic pathways to make Synechocystis sp. PCC6803 adapt to glucose mixotrophic conditions. This study showed that the deletion of slr0643 damaged multiple metabolic pathways in cells, thereby making the cells unable to utilize glucose normally, and Slr0643 plays an important role in the acclimation of Synechocystis sp. PCC6803 to glucose mixotrophic conditions.

国家自然科学基金面上项目（31270085）；广东省自然科学基金项目（2018A030313783）