Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan.
Department of Biochemistry, Niigata University, Niigata 950-218, Japan.
Int J Mol Sci. 2018 Sep 7;19(9):2655. doi: 10.3390/ijms19092655.
Rice nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) catalyzes the hydrolytic breakdown of the pyrophosphate and phosphodiester bonds of a number of nucleotides including ADP-glucose and ATP. Under high temperature and elevated CO₂ conditions (HT + ECO₂), the knockout rice mutant displayed rapid growth and high starch content phenotypes, indicating that exerts a negative effect on starch accumulation and growth. To gain further insight into the mechanisms involved in the downregulation induced starch overaccumulation, in this study we conducted photosynthesis, leaf proteomic, and chloroplast phosphoproteomic analyses of wild-type (WT) and plants cultured under HT + ECO₂. Photosynthesis in leaves was significantly higher than in WT. Additionally, leaves accumulated higher levels of sucrose than WT. The proteomic analyses revealed upregulation of proteins related to carbohydrate metabolism and the protein synthesis system in plants. Further, our data indicate the induction of 14-3-3 proteins in plants. Our finding demonstrates a higher level of protein phosphorylation in chloroplasts, which may play an important role in carbohydrate accumulation. Together, these results offer novel targets and provide additional insights into carbohydrate metabolism regulation under ambient and adverse conditions.
核苷酸二磷酸酶 1（NPP1）可催化包括 ADP-葡萄糖和 ATP 在内的多种核苷酸的焦磷酸和磷酸二酯键的水解。在高温和高 CO₂条件下（HT+ECO₂），敲除水稻突变体表现出快速生长和高淀粉含量的表型，表明其对淀粉积累和生长有负向作用。为了进一步深入了解下调诱导淀粉过度积累的机制，本研究对 HT+ECO₂下培养的野生型（WT）和突变体植株进行了光合作用、叶片蛋白质组学和叶绿体磷蛋白组学分析。突变体叶片的光合作用明显高于 WT。此外，突变体叶片中蔗糖的积累水平高于 WT。蛋白质组学分析表明，突变体中与碳水化合物代谢和蛋白质合成系统相关的蛋白质上调。此外，我们的数据表明，突变体中诱导了 14-3-3 蛋白。我们的发现表明，叶绿体中存在更高水平的蛋白质磷酸化，这可能在碳水化合物积累中发挥重要作用。总之，这些结果为环境和逆境条件下碳水化合物代谢的调控提供了新的靶点和更深入的认识。
