• Stress and nutrient availability influence cell proliferation through complex intracellular signalling networks. In a previous study it was found that pyro-inositol polyphosphates (InsP₇ and InsP₈) produced by VIP1 kinase, and target of rapamycin (TOR) kinase signalling interacted synergistically to control cell growth and lipid metabolism in the green alga Chlamydomonas reinhardtii. However, the relationship between InsPs and TOR was not completely elucidated.
• We used an in vivo assay for TOR activity together with global proteomic and phosphoproteomic analyses to assess differences between wild-type and vip1-1 in the presence and absence of rapamycin.
• We found that TOR signalling is more severely affected by the inhibitor rapamycin in a vip1-1 mutant compared with wild-type, indicating that InsP₇ and InsP₈ produced by VIP1 act independently but also coordinately with TOR. Additionally, among hundreds of differentially phosphorylated peptides detected, an enrichment for photosynthesis-related proteins was observed, particularly photosystem II proteins. The significance of these results was underscored by the finding that vip1-1 strains show multiple defects in photosynthetic physiology that were exacerbated under high light conditions.
• These results suggest a novel role for inositol pyrophosphates and TOR signalling in coordinating photosystem phosphorylation patterns in Chlamydomonas cells in response to light stress and possibly other stresses.

中文翻译：

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多磷酸肌醇和雷帕霉素激酶信号靶点控制光系统 II 蛋白磷酸化和光合功能在光胁迫下衣藻

• 压力和营养供应通过复杂的细胞内信号网络影响细胞增殖。在之前的一项研究中发现，由 VIP1 激酶产生的焦肌醇多磷酸盐（InsP ₇和 InsP ₈）与雷帕霉素 (TOR) 激酶信号传导靶点协同相互作用以控制绿藻莱茵衣藻中的细胞生长和脂质代谢。然而，InsPs 和 TOR 之间的关系尚未完全阐明。
• 我们使用TOR 活性的体内测定以及整体蛋白质组学和磷酸化蛋白质组学分析来评估在存在和不存在雷帕霉素的情况下野生型和vip1-1之间的差异。
• 我们发现，与野生型相比，vip1-1突变体中的抑制剂雷帕霉素对 TOR 信号传导的影响更严重，这表明VIP1产生的 InsP ₇和 InsP ₈独立作用，但也与 TOR 协同作用。此外，在检测到的数百种差异磷酸化肽中，观察到光合作用相关蛋白的富集，特别是光系统 II 蛋白。发现vip1-1菌株在高光条件下加剧了光合生理学的多个缺陷，这一发现强调了这些结果的重要性。
• 这些结果表明肌醇焦磷酸和 TOR 信号在协调衣藻细胞中光系统磷酸化模式以响应光胁迫和可能的其他胁迫中的新作用。