Autophagy Deficiency Compromises Alternative Pathways of Respiration following Energy Deprivation in Arabidopsis thaliana
Autophagy Deficiency Compromises Alternative Pathways of Respiration following Energy Deprivation in Arabidopsis thaliana
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DOI：
10.1104/pp.16.01576
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发表时间：
2017-09-01
期刊：
影响因子：
7.4
通讯作者：
Araujo, Wagner L.
中科院分区：
文献类型：
--
作者：
Barros, Jessica A. S.;Cavalcanti, Joao Henrique F.;Araujo, Wagner L.
在异养条件下，碳水化合物在胞内的氧化是细胞代谢的主要能量来源。然而，在能量有限的条件下，需要替代底物来支持呼吸。植物细胞中的氨基酸氧化通过产生电子在其中起关键作用，所述电子可以经由电子转移黄素蛋白/泛醌氧化还原酶系统转移到线粒体电子传递链。自噬是大分子和蛋白质循环的一种分解代谢机制，可以维持氨基酸库和营养物质的再动员。虽然自噬和替代性呼吸底物之间的关联已经被提出，但自噬和初级代谢相互作用以支持植物呼吸的程度仍不清楚。为了研究发育期间和延长黑暗下自噬的代谢重要性，使用具有自噬破坏的拟南芥（Arabidopsis thaliana）突变体（atg突变体）。在正常生长条件下，atg突变体表现出较低的生长和种子产量，但对光合作用没有影响。延长黑暗后，atg突变体的特点是早期衰老的签名，包括叶绿素含量下降，光系统II的最大光化学效率加上增加暗呼吸。atg突变体中参与呼吸和氨基酸催化剂替代途径的基因转录水平上调。黑暗处理的叶片的代谢产物分布揭示了广泛的代谢重编程，其中氨基酸水平的增加部分损害atg突变体。尽管在延长的黑暗中观察到atg突变体的呼吸增强，但自噬缺陷会影响蛋白质降解和作为呼吸替代底物的氨基酸的产生。
Under heterotrophic conditions, carbohydrate oxidation inside the mitochondrion is the primary energy source for cellular metabolism. However, during energy-limited conditions, alternative substrates are required to support respiration. Amino acid oxidation in plant cells plays a key role in this by generating electrons that can be transferred to the mitochondrial electron transport chain via the electron transfer flavoprotein/ubiquinone oxidoreductase system. Autophagy, a catabolic mechanism for macromolecule and protein recycling, allows the maintenance of amino acid pools and nutrient remobilization. Although the association between autophagy and alternative respiratory substrates has been suggested, the extent to which autophagy and primary metabolism interact to support plant respiration remains unclear. To investigate the metabolic importance of autophagy during development and under extended darkness, Arabidopsis (Arabidopsis thaliana) mutants with disruption of autophagy (atg mutants) were used. Under normal growth conditions, atg mutants showed lower growth and seed production with no impact on photosynthesis. Following extended darkness, atg mutants were characterized by signatures of early senescence, including decreased chlorophyll content and maximum photochemical efficiency of photosystem II coupled with increases in dark respiration. Transcript levels of genes involved in alternative pathways of respiration and amino acid catabolism were up-regulated in atg mutants. The metabolite profiles of dark-treated leaves revealed an extensive metabolic reprogramming in which increases in amino acid levels were partially compromised in atg mutants. Although an enhanced respiration in atg mutants was observed during extended darkness, autophagy deficiency compromises protein degradation and the generation of amino acids used as alternative substrates to the respiration.