Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Department of Chemistry, Marshall University, Huntington, WV 25755, USA.
Cells. 2019 Sep 28;8(10):1171. doi: 10.3390/cells8101171.
The target of rapamycin (TOR) kinase is a master metabolic regulator with roles in nutritional sensing, protein translation, and autophagy. In , a unicellular green alga, TOR has been linked to the regulation of increased triacylglycerol (TAG) accumulation, suggesting that TOR or a downstream target(s) is responsible for the elusive "lipid switch" in control of increasing TAG accumulation under nutrient limitation. However, while TOR has been well characterized in mammalian systems, it is still poorly understood in photosynthetic systems, and little work has been done to show the role of oxidative signaling in TOR regulation. In this study, the TOR inhibitor AZD8055 was used to relate reversible thiol oxidation to the physiological changes seen under TOR inhibition, including increased TAG content. Using oxidized cysteine resin-assisted capture enrichment coupled with label-free quantitative proteomics, 401 proteins were determined to have significant changes in oxidation following TOR inhibition. These oxidative changes mirrored characterized physiological modifications, supporting the role of reversible thiol oxidation in TOR regulation of TAG production, protein translation, carbohydrate catabolism, and photosynthesis through the use of reversible thiol oxidation. The delineation of redox-controlled proteins under TOR inhibition provides a framework for further characterization of the TOR pathway in photosynthetic eukaryotes.
雷帕霉素靶蛋白（TOR）激酶是一种主要的代谢调节剂，在营养感应、蛋白质翻译和自噬中发挥作用。在单细胞绿藻中，TOR 与增加三酰基甘油（TAG）积累的调节有关，这表明 TOR 或其下游靶标负责在营养限制下控制增加的 TAG 积累的难以捉摸的“脂质开关”。然而，虽然 TOR 在哺乳动物系统中得到了很好的描述，但在光合作用系统中仍知之甚少，而且很少有工作表明氧化信号在 TOR 调节中的作用。在这项研究中，使用 TOR 抑制剂 AZD8055 将可逆硫醇氧化与 TOR 抑制下观察到的生理变化联系起来，包括增加的 TAG 含量。使用氧化半胱氨酸树脂辅助捕获富集结合无标记定量蛋白质组学，确定了 401 种蛋白质在 TOR 抑制后发生了显著的氧化变化。这些氧化变化与特征性的生理修饰相吻合，支持可逆硫醇氧化在 TOR 调节 TAG 产生、蛋白质翻译、碳水化合物分解代谢和光合作用中的作用，通过使用可逆硫醇氧化。TOR 抑制下的氧化还原控制蛋白的描绘为进一步表征光合真核生物中的 TOR 途径提供了框架。
