Growth-temperature stress causes biochemical changes in the cells and reduction of biomass yield. Quantitative proteome of Arthrospira platensis C1 in response to low- and high temperature stresses was previously analysed to elucidate the stress response mechanism. The data highlighted the linkage of signaling proteins and proteins involved in nitrogen and ammonia assimilation, photosynthesis and oxidative stress. After phosphoproteome analysis was carried out in this study, the tentative temperature response cascade of A. platensis C1 was drawn based on data integration of quantitative proteome and phosphoproteome analysis and protein-protein interaction (PPI) networks. The integration revealed 31 proteins regulated at the protein-expression and post-translational levels; thus, this group of proteins was designated bi-level regulated proteins. PPI networks were then constructed based on A. platensis C1 gene inference from publicly available interaction data. The key two-component system (TCS) proteins, SPLC1_S082010 and SPLC1_S230960, were identified as bi-level regulated proteins and were linked to SPLC1_S270380 or glutamate synthase, an important enzyme in nitrogen assimilation that synthesizes glutamate from 2-oxoglutarate, which is known as the signal compound that regulates the carbon/nitrogen (C/N) balance of cells. Moreover, the role of the p-site in the PPIs of some phosphoproteins of interest was determined using site-directed mutagenesis and a yeast two-hybrid system. Evidence showing the critical role of the p-site in the PPI was observed for the multi-sensor histidine kinase SPLC1_S041070 (Hik28) and glutamate synthase. PPI subnetwork also showed that the Hik28 involved with the enzymes in fatty acid desaturation and nitrogen metabolism. The effect of Hik28-deletion was validated by fatty acid analysis and measurement of photosynthetic activity under nitrogen depletion. Taken together, the data clearly represents (i) the multi-level regulation of proteins involved in the stress response mechanism and (ii) the key point of the temperature stress response at the interconnection of C- and N- metabolism.

中文翻译：

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通过蛋白质组学分析和PPI网络揭示了C.N代谢相互联系的Arthrospira platensis C1温度胁迫反应的关键点。

生长温度胁迫导致细胞中的生化变化并降低生物质产量。先前已分析了对低温和高温胁迫响应的节肢动物Arthrospira platensis C1的定量蛋白质组，以阐明应力响应机制。数据突出了信号蛋白与参与氮和氨同化，光合作用和氧化应激的蛋白之间的联系。在本研究中进行了磷酸化蛋白质组分析之后，基于定量蛋白质组学和磷酸化蛋白质组分析的数据集成以及蛋白质-蛋白质相互作用（PPI）网络，绘制了拟南芥C1的暂定温度响应级联。整合揭示了31种受蛋白质表达和翻译后水平调控的蛋白质。因此，这组蛋白被称为双水平调节蛋白。然后根据来自公开的交互作用数据的白僵菌C1基因推断，构建PPI网络。关键的两组分系统（TCS）蛋白SPLC1_S082010和SPLC1_S230960被鉴定为双水平调节蛋白，并与SPLC1_S270380或谷氨酸合酶连接，谷氨酸合酶是氮同化中的一种重要酶，可以从2-氧代戊二酸合成谷氨酸。调节细胞碳/氮（C / N）平衡的信号化合物。此外，使用定点诱变和酵母双杂交系统确定了p-位在某些目的磷酸蛋白的PPI中的作用。对于多传感器组氨酸激酶SPLC1_S041070（Hik28）和谷氨酸合酶，观察到显示p位在PPI中至关重要的证据。PPI子网还显示，Hik28与酶参与脂肪酸去饱和和氮代谢。Hik28缺失的影响通过脂肪酸分析和氮耗竭下光合作用的测定来验证。综上所述，数据清楚地表示（i）参与应激反应机制的蛋白质的多级调节，以及（ii）C-和N-新陈代谢互连时温度应激反应的关键点。