The ATG Autophagic Conjugation System in Maize: ATG Transcripts and Abundance of the ATG8-Lipid Adduct Are Regulated by Development and Nutrient Availability
The ATG Autophagic Conjugation System in Maize: ATG Transcripts and Abundance of the ATG8-Lipid Adduct Are Regulated by Development and Nutrient Availability
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DOI：
10.1104/pp.108.126714
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发表时间：
2009-01-01
期刊：
影响因子：
7.4
通讯作者：
Vierstra, Richard D.
中科院分区：
文献类型：
--
作者：
Chung, Taijoon;Suttangkakul, Anongpat;Vierstra, Richard D.
植物利用复杂的机制来循环细胞内的成分，这些成分是在营养限制的条件下生长、发育和生存所需的。自噬是细胞质和细胞器大量滞留到小泡中，随后被滞留的水解酶分解到液泡中的一种重要途径。自噬小泡的形成和运输在一定程度上是由相关的接合级联反应控制的，该级联反应将自噬相关的8(ATG8)和ATG12蛋白连接到它们各自的靶标磷脂酰乙醇胺和ATG5蛋白。为了帮助理解自噬对谷物中营养物质再动员的重要性，我们在这里描述了玉米(Zea Mays)中的ATG8/12接合级联，并研究了它们在发育、叶片衰老以及氮和固定碳饥饿过程中的动态。通过对玉米基因组序列的检索，我们确定了编码ATG8/12接合所必需的所有组分的同源基因座，其中包括一个表达ATG8的五成员基因家族。选择性剪接在几乎所有的ATG转录本中都很明显，这可能会产生重要的调控后果。除了游离的ATG8外，在许多玉米组织中还检测到其膜相关的脂化形式，这表明它的接合级联在整个植株的大部分(如果不是全部)发育阶段都是活跃的。ATG转录本和/或ATG8-磷脂酰乙醇胺加合物的水平在叶片衰老和氮和固定碳限制期间增加，表明自噬在营养物质再动员中发挥关键作用。玉米ATG系统的描述现在提供了一系列分子和生化工具来研究这种作物在田间条件下的自噬。
Plants employ sophisticated mechanisms to recycle intracellular constituents needed for growth, development, and survival under nutrient-limiting conditions. Autophagy is one important route in which cytoplasm and organelles are sequestered in bulk into vesicles and subsequently delivered to the vacuole for breakdown by resident hydrolases. The formation and trafficking of autophagic vesicles are directed in part by associated conjugation cascades that couple the AUTOPHAGY-RELATED8 (ATG8) and ATG12 proteins to their respective targets, phosphatidylethanolamine and the ATG5 protein. To help understand the importance of autophagy to nutrient remobilization in cereals, we describe here the ATG8/12 conjugation cascades in maize (Zea mays) and examine their dynamics during development, leaf senescence, and nitrogen and fixed-carbon starvation. From searches of the maize genomic sequence using Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) counterparts as queries, we identified orthologous loci encoding all components necessary for ATG8/12 conjugation, including a five-member gene family expressing ATG8. Alternative splicing was evident for almost all Atg transcripts, which could have important regulatory consequences. In addition to free ATG8, its membrane-associated, lipidated form was detected in many maize tissues, suggesting that its conjugation cascade is active throughout the plant at most, if not all, developmental stages. Levels of Atg transcripts and/or the ATG8-phosphatidylethanolamine adduct increase during leaf senescence and nitrogen and fixed-carbon limitations, indicating that autophagy plays a key role in nutrient remobilization. The description of the maize ATG system now provides a battery of molecular and biochemical tools to study autophagy in this crop under field conditions.