GFS9 Affects Piecemeal Autophagy of Plastids in Young Seedlings of Arabidopsis thaliana.
GFS9 Affects Piecemeal Autophagy of Plastids in Young Seedlings of Arabidopsis thaliana.
复制标题
GFS9 影响拟南芥幼苗质体的碎片自噬。
DOI：
10.1093/pcp/pcab084
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
K.J.
中科院分区：
文献类型：
--
作者：
Ishida;H.;Okashita;Y.;Ishida H.;Hayashi;M.;Izumi;M.;Amane Makino;A.;Bhuiyan;N.H. and Van Wijk;K.J.
叶绿体和一般的叶绿体含有丰富的蛋白质池，可以成为循环利用的主要碳和氮来源。我们以前已经证明，叶绿体通过含有Rubisco的小体被分段自噬部分地和顺序地降解。这种退化发生在植物发育期间和对环境的反应；然而，人们对基本的潜在机制知之甚少。为了揭示叶绿体/叶绿体片段自噬的机制，我们对表达叶绿体靶向绿色荧光蛋白(CT-GFP)的拟南芥转基因株系进行了甲烷磺酸乙酯诱变后的正向遗传学筛选。该突变体gfs9-5可在幼苗中超量积累直径达1 μm的CT-gfp标记的细胞质小体。我们将这些结构称为质体(PBS)。该突变体缺乏膜转运因子绿色荧光种子9(GFS9)，黑暗和营养缺乏促进了Pb9-5的积累。透射电子显微镜显示，gfs9-5与自噬小体和pBs.gfs9-5超积累的膜结合内源ATG8蛋白、转基因黄色荧光蛋白(YFP)-ATG8e蛋白和YFP-ATG8e标记的自噬体样结构相对应。YFP-ATG8e信号与叶绿体表面及其突起有关。Gfs9和自噬缺陷5的双突变体不积累PBS。在Ingfs9-5中，YFP-ATG8e蛋白和PBS可被运送到液泡中，自噬通量增加。我们讨论了GFS9和自噬之间的可能联系，并建议将gfs9-5作为一种新的工具用于研究片段性叶绿体自噬。
Chloroplasts, and plastids in general, contain abundant protein pools that can be major sources of carbon and nitrogen for recycling. We have previously shown that chloroplasts are partially and sequentially degraded by piecemeal autophagy via the Rubisco-containing body. This degradation occurs during plant development and in response to the environment; however, little is known about the fundamental underlying mechanisms. To discover the mechanisms of piecemeal autophagy of chloroplasts/plastids, we conducted a forward-genetics screen following ethyl-methanesulfonate mutagenesis of an Arabidopsis (Arabidopsis thaliana) transgenic line expressing chloroplast-targeted green fluorescent protein (CT-GFP). This screen allowed us to isolate a mutant,gfs9-5, which hyperaccumulated cytoplasmic bodies labeled with CT-GFP of up to 1.0 μm in diameter in the young seedlings. We termed these structures plastid bodies (PBs). The mutant was defective in a membrane-trafficking factor, green fluorescent seed 9 (GFS9), and PB accumulation ingfs9-5was promoted by darkness and nutrient deficiency. Transmission electron microscopy indicated thatgfs9-5hyperaccumulated structures corresponding to autophagosomes and PBs.gfs9-5hyperaccumulated membrane-bound endogenous ATG8 proteins, transgenic yellow fluorescent protein (YFP)-ATG8e proteins and autophagosome-like structures labeled with YFP-ATG8e. The YFP-ATG8e signal was associated with the surface of plastids and their protrusions ingfs9-5. Double mutants ofgfs9andautophagy-defective 5did not accumulate PBs. Ingfs9-5, the YFP-ATG8e proteins and PBs could be delivered to the vacuole and autophagic flux was increased. We discuss a possible connection between GFS9 and autophagy and propose a potential use ofgfs9-5as a new tool to study piecemeal plastid autophagy.