The mitochondrial pyruvate carrier (MPC) complex mediates one of three pyruvate-supplying pathways that sustain Arabidopsis respiratory metabolism
The mitochondrial pyruvate carrier (MPC) complex mediates one of three pyruvate-supplying pathways that sustain Arabidopsis respiratory metabolism
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DOI：
10.1093/plcell/koab148
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发表时间：
2021-06-17
期刊：
影响因子：
11.6
通讯作者：
Millar, A. Harvey
中科院分区：
文献类型：
--
作者：
Le, Xuyen H.;Lee, Chun-Pong;Millar, A. Harvey
通过植物线粒体的苹果酸氧化使得能够产生草酰乙酸和丙酮酸两者用于三羧酸（TCA）循环功能，潜在地消除了丙酮酸转运到植物中的线粒体中的需要。在这里，我们表明，线粒体丙酮酸载体1（MPC 1）的情况下，导致其推定的直系同源物，MPC 3/MPC 4的共同承诺损失，并消除丙酮酸运输到拟南芥线粒体，证明它是必不可少的MPC复杂的功能。虽然MPC或线粒体生成NAD-苹果酸酶（NAD-ME）的损失并没有引起营养表型，但两者的缺乏降低了植物生长并引起细胞丙酮酸水平的增加，表明呼吸代谢受阻，并在夜间升高了支链氨基酸的水平，这是呼吸底物供应改变的标志。C-13-丙酮酸喂养缺乏MPC的叶子显示代谢稳态在很大程度上保持除了丙氨酸和谷氨酸，这表明转氨作用有助于恢复代谢网络的操作平衡，通过将丙酮酸独立于MPC递送到基质中。抑制丙氨酸氨基转移酶时，MPC 1是不存在的拟南芥中导致极其迟缓的表型，这表明所有的琥珀酸供应酶协同工作，以支持持续植物生长的TCA循环。
Malate oxidation by plant mitochondria enables the generation of both oxaloacetate and pyruvate for tricarboxylic acid (TCA) cycle function, potentially eliminating the need for pyruvate transport into mitochondria in plants. Here, we show that the absence of the mitochondrial pyruvate carrier 1 (MPC1) causes the co-commitment loss of its putative orthologs, MPC3/MPC4, and eliminates pyruvate transport into Arabidopsis thaliana mitochondria, proving it is essential for MPC complex function. While the loss of either MPC or mitochondrial pyruvate-generating NAD-malic enzyme (NAD-ME) did not cause vegetative phenotypes, the lack of both reduced plant growth and caused an increase in cellular pyruvate levels, indicating a block in respiratory metabolism, and elevated the levels of branched-chain amino acids at night, a sign of alterative substrate provision for respiration. C-13-pyruvate feeding of leaves lacking MPC showed metabolic homeostasis was largely maintained except for alanine and glutamate, indicating that transamination contributes to the restoration of the metabolic network to an operating equilibrium by delivering pyruvate independently of MPC into the matrix. Inhibition of alanine aminotransferases when MPC1 is absent resulted in extremely retarded phenotypes in Arabidopsis, suggesting all pyruvate-supplying enzymes work synergistically to support the TCA cycle for sustained plant growth.