ATG8 lipidation and ATG8-mediated autophagy in Arabidopsis require ATG12 expressed from the differentially controlled ATG12A AND ATG12B loci
ATG8 lipidation and ATG8-mediated autophagy in Arabidopsis require ATG12 expressed from the differentially controlled ATG12A AND ATG12B loci
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DOI：
10.1111/j.1365-313x.2010.04166.x
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发表时间：
2010-05-01
期刊：
影响因子：
7.2
通讯作者：
Vierstra, Richard D.
中科院分区：
文献类型：
--
作者：
Chung, Taijoon;Phillips, Allison R.;Vierstra, Richard D.
在正常生长条件下，植物细胞内成分的自噬再循环维持在基础水平，但可响应营养需求、生物胁迫和衰老而被诱导。一种途径需要泛素折叠蛋白自噬相关（ATG）-8和ATG 12，它们在吞噬囊泡形成和将其货物递送到液泡进行分解期间分别与脂质磷脂酰乙醇胺（PE）和ATG 5蛋白连接。在这里，我们遗传分析所需的共轭机制ATG 8/12的修改拟南芥的重点是两个基因座编码ATG 12。而单一的atg 12 a和atg 12 b突变体缺乏表型的后果，atg 12 a atg 12 b双突变体衰老过早，对氮和固定碳饥饿过敏，不能积累自噬体在液泡。通过将消除ATG 12 a/B、ATG 5或其缩合所需的ATG 10 E2的突变体与明确检测ATG 8-PE加合物的方法相结合，我们还表明ATG 8脂化需要ATG 12-ATG 5缀合物。与ATG 8不同，ATG 12不与自噬体相关，这意味着其在自噬过程中的作用仅限于囊泡的空泡沉积之前的事件。ATG 12 a和ATG 12 b基因的表达模式以及单个atg 12 a和atg 12 b突变体对形成ATG 12-ATG 5缀合物的影响揭示了ATG 12 b基因座在基础自噬期间更重要，而ATG 12 a基因座在诱导自噬期间更重要。综上所述，我们得出结论，ATG 12-ATG 5加合物的形成是至关重要的ATG 8介导的自噬在植物中通过促进ATG 8脂化。
P>Autophagic recycling of intracellular plant constituents is maintained at a basal level under normal growth conditions but can be induced in response to nutritional demand, biotic stress, and senescence. One route requires the ubiquitin-fold proteins Autophagy-related (ATG)-8 and ATG12, which become attached to the lipid phosphatidylethanolamine (PE) and the ATG5 protein, respectively, during formation of the engulfing vesicle and delivery of its cargo to the vacuole for breakdown. Here, we genetically analyzed the conjugation machinery required for ATG8/12 modification in Arabidopsis thaliana with a focus on the two loci encoding ATG12. Whereas single atg12a and atg12b mutants lack phenotypic consequences, atg12a atg12b double mutants senesce prematurely, are hypersensitive to nitrogen and fixed carbon starvation, and fail to accumulate autophagic bodies in the vacuole. By combining mutants eliminating ATG12a/b, ATG5, or the ATG10 E2 required for their condensation with a method that unequivocally detects the ATG8-PE adduct, we also show that ATG8 lipidation requires the ATG12-ATG5 conjugate. Unlike ATG8, ATG12 does not associate with autophagic bodies, implying that its role(s) during autophagy is restricted to events before the vacuolar deposition of vesicles. The expression patterns of the ATG12a and ATG12b genes and the effects of single atg12a and atg12b mutants on forming the ATG12-ATG5 conjugate reveal that the ATG12b locus is more important during basal autophagy while the ATG12a locus is more important during induced autophagy. Taken together, we conclude that the formation of the ATG12-ATG5 adduct is essential for ATG8-mediated autophagy in plants by promoting ATG8 lipidation.