Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Metabolites. 2014 Jun 30;4(3):517-31. doi: 10.3390/metabo4030517.
Nutrient balance is important for photosynthetic growth and biomass production in microalgae. Here, we investigated and compared metabolic responses of amino acid pools to nitrogen and sulfur starvation in a unicellular model cyanobacterium, Synechocystis sp. PCC 6803, and its mutant nblA1/A2. It is known that NblA1/A2-dependent and -independent breakdown of abundant photosynthetic phycobiliproteins and other cellular proteins supply nutrients to the organism. However, the contribution of the NblA1/A2-dependent nutrient supply to amino acid pool homeostasis has not been studied. Our study demonstrates that changes in the pool size of many amino acids during nitrogen starvation can be categorized as NblA1/A2-dependent (Gln, Glu, glutathione, Gly, Ile, Leu, Met, Phe, Pro, Ser, Thr, Tyr and Val) and NblA1/A2-independent (Ala, Asn, Lys, and Trp). We also report unique changes in amino acid pool sizes during sulfur starvation in wild type and the mutant and found a generally marked increase in the Lys pool in cyanobacteria during nutrient starvation. In conclusion, the NblA1/A2-dependent protein turnover contributes to the maintenance of many amino acid pools during nitrogen starvation.
营养平衡对微藻的光合作用生长和生物量生产至关重要。在这里,我们研究并比较了氮和硫饥饿对单细胞模式蓝藻集胞藻 6803 及其突变体 nblA1/A2 中氨基酸库的代谢反应。众所周知,NblA1/A2 依赖性和非依赖性分解丰富的光合作用藻胆蛋白和其他细胞蛋白为生物体提供营养。然而,NblA1/A2 依赖性营养供应对氨基酸库动态平衡的贡献尚未得到研究。我们的研究表明,氮饥饿过程中许多氨基酸库大小的变化可分为 NblA1/A2 依赖性(Gln、Glu、谷胱甘肽、Gly、Ile、Leu、Met、Phe、Pro、Ser、Thr、Tyr 和 Val)和 NblA1/A2 非依赖性(Ala、Asn、Lys 和 Trp)。我们还报告了野生型和突变体在硫饥饿期间氨基酸库大小的独特变化,并发现营养饥饿期间蓝细菌中 Lys 库普遍显著增加。总之,NblA1/A2 依赖性蛋白周转有助于维持氮饥饿期间许多氨基酸库的稳定。