While the role of TOR kinase in the chloroplast biogenesis and transcriptional regulation of photosynthesis is well documented in Arabidopsis, the functional relevance of this metabolic sensor kinase in chloroplast–mitochondria cross talk is unknown. Using Chlamydomonas reinhardtii as the model system, we demonstrate the role of TOR kinase in the regulation of chloroplast and mitochondrial functions: We show that TOR kinase inhibition impairs the maintenance of high ETR associated with PSII and low NPQ and inhibits efficient state transitions between PSII and PSI. While compromised photosynthetic functions are observed in TOR kinase inhibited cells, same conditions lead to augmentation in mitochondrial basal respiration rate by twofold and concomitantly a rise in ATP production. Interestingly, such upregulated mitochondrial functions in TOR‐inhibited cells are mediated by fragmented mitochondria via upregulating COXIIb and downregulating Hxk1 and AOX1 protein levels. We propose that TOR kinase may act as a sensor that counter‐regulates chloroplast versus mitochondrial functions in a normal C. reinhardtii cell.

中文翻译：

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莱茵衣藻 TOR 激酶对光合作用和线粒体呼吸的相互调节。

虽然 TOR 激酶在叶绿体生物合成和光合作用转录调控中的作用在拟南芥中已有详细记录，但这种代谢传感器激酶在叶绿体-线粒体串扰中的功能相关性尚不清楚。使用莱茵衣藻作为模型系统，我们证明了 TOR 激酶在叶绿体和线粒体功能调节中的作用：我们发现 TOR 激酶抑制会损害与 PSII 和低 NPQ 相关的高 ETR 的维持，并抑制 PSII 和 NPQ 之间的有效状态转换。 PSI。虽然在 TOR 激酶抑制的细胞中观察到光合功能受损，但相同的条件导致线粒体基础呼吸速率增加两倍，同时 ATP 产量增加。有趣的是，TOR 抑制细胞中线粒体功能的上调是由碎片化线粒体通过上调 COXIIb 和下调 Hxk1 和 AOX1 蛋白水平介导的。我们认为 TOR 激酶可能充当传感器，在正常莱茵衣藻细胞中反调节叶绿体与线粒体功能。