Physiological and metabolic consequences of autophagy deficiency for the management of nitrogen and protein resources in Arabidopsis leaves depending on nitrate availability
Physiological and metabolic consequences of autophagy deficiency for the management of nitrogen and protein resources in Arabidopsis leaves depending on nitrate availability
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DOI：
10.1111/nph.12307
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发表时间：
2013-08-01
期刊：
影响因子：
9.4
通讯作者：
Masclaux-Daubresse, Celine
中科院分区：
文献类型：
--
作者：
Guiboileau, Anne;Avila-Ospina, Liliana;Masclaux-Daubresse, Celine
自噬存在于所有植物组织中的基础水平，并在叶子衰老过程中和响应氮 (N) 饥饿时被诱导。在自噬突变体中，氮从莲座丛到种子的再动员受到损害。本报告重点关注自噬在植物衰老过程中叶片氮管理和蛋白水解中的作用。对在低硝酸盐和高硝酸盐条件下生长的几种自噬缺陷（atg）拟南芥突变体的代谢物、酶活性和蛋白质含量进行了监测。结果表明，在任何衰老症状出现之前，atg 突变体的碳（C）和氮状态受到影响。 atg突变体比野生型积累了更多的铵、氨基酸和蛋白质，并且糖含量耗尽。尽管内肽酶和羧肽酶活性较高，atg 突变体中蛋白质的过度积累是有选择性的并且发生。观察到核糖体蛋白 S6 和 L13 亚基以及过氧化氢酶和谷氨酸脱氢酶蛋白的特异性过度积累。 atg 突变体还积累了推测为 Rubisco 大亚基和谷氨酰胺合成酶 2 (GS2) 降解产物的肽。自噬缺陷导致的叶绿体蛋白降解不完全可以解释 atg 花结中测得的较高氮浓度和氮再动员缺陷。结论是自噬控制拟南芥叶片中的 C : N 状态和蛋白质含量。
Autophagy is present at a basal level in all plant tissues and is induced during leaf ageing and in response to nitrogen (N) starvation. Nitrogen remobilization from the rosette to the seeds is impaired in autophagy mutants. This report focuses on the role of autophagy in leaf N management and proteolysis during plant ageing.Metabolites, enzyme activities and protein contents were monitored in several autophagy-defective (atg) Arabidopsis mutants grown under low and high nitrate conditions.Results showed that carbon (C) and N statuses were affected in atg mutants before any senescence symptoms appeared. atg mutants accumulated larger amounts of ammonium, amino acids and proteins than wild type, and were depleted in sugars. Over-accumulation of proteins in atg mutants was selective and occurred despite higher endopeptidase and carboxypeptidase activities. Specific over-accumulation of the ribosomal proteins S6 and L13 subunits, and of catalase and glutamate dehydrogenase proteins was observed. atg mutants also accumulated peptides putatively identified as degradation products of the Rubisco large subunit and glutamine synthetase 2 (GS2). Incomplete chloroplast protein degradation resulting from autophagy defects could explain the higher N concentrations measured in atg rosettes and defects in N remobilization.It is concluded that autophagy controls C : N status and protein content in leaves of Arabidopsis.