Impaired PSII proteostasis triggers a UPR-like response in the var2 mutant of Arabidopsis
Impaired PSII proteostasis triggers a UPR-like response in the var2 mutant of Arabidopsis
复制标题
PSII 蛋白质稳态受损会在拟南芥 var2 突变体中引发类似 UPR 的反应
DOI：
10.1093/jxb/erz151
复制
发表时间：
2019-06-01
影响因子：
6.9
通讯作者：
Kim, Chanhong
中科院分区：
文献类型：
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作者：
Dogra, Vivek;Duan, Jianli;Kim, Chanhong
细胞蛋白质稳态（proteostasis）是通过从头合成和蛋白质水解之间的平衡来维持的。应激内质网（ER）触发的未折叠/错误折叠蛋白反应（UPR）在植物和动物的蛋白质静止中也起着重要作用。虽然er触发的UPR已经在植物中得到了广泛的研究，但线粒体和叶绿体UPR的分子机制在很大程度上还没有被表征，尽管这些细胞器是产生有害活性氧（ROS）的场所，而活性氧会损害蛋白质。在这项研究中，我们证明了缺乏金属蛋白酶FtsH2的拟南芥黄叶杂化2 （var2）突变体的叶绿体积累受损的叶绿体蛋白并引发类似upra的反应，即积累一套参与蛋白质质量控制（PQC）的叶绿体蛋白。这些PQC蛋白包括热休克蛋白、伴侣蛋白、蛋白酶和活性氧解毒剂。考虑到FtsH2主要在光系统II蛋白中起作用，pqc相关蛋白的积累可能会平衡FtsH2的缺乏。此外，同源转录本的明显上调表明，pqc相关蛋白在var2中的积累可能是由逆行信号介导的，表明var2中发生了类似upr的反应。
Cellular protein homeostasis (proteostasis) is maintained through the balance between de novo synthesis and proteolysis. The unfolded/misfolded protein response (UPR) that is triggered by stressed endoplasmic reticulum (ER) also plays an important role in proteostasis in both plants and animals. Although ER-triggered UPR has been extensively studied in plants, the molecular mechanisms underlying mitochondrial and chloroplastic UPRs are largely uncharacterized despite the fact that these organelles are sites of production of harmful reactive oxygen species (ROS), which damage proteins. In this study, we demonstrate that chloroplasts of the Arabidopsis yellow leaf variegation 2 (var2) mutant, which lacks the metalloprotease FtsH2, accumulate damaged chloroplast proteins and trigger a UPR-like response, namely the accumulation of a suite of chloroplast proteins involved in protein quality control (PQC). These PQC proteins include heat-shock proteins, chaperones, proteases, and ROS detoxifiers. Given that FtsH2 functions primarily in photosystem II proteostasis, the accumulation of PQC-related proteins may balance the FtsH2 deficiency. Moreover, the apparent up-regulation of the cognate transcripts indicates that the accumulation of PQC-related proteins in var2 is probably mediated by retrograde signaling, indicating the occurrence of a UPR-like response in var2.