Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
University of the Chinese Academy of Sciences, Beijing 100049, China.
Int J Mol Sci. 2021 Nov 9;22(22):12106. doi: 10.3390/ijms222212106.
Low and high temperatures are life-threatening stress factors, diminishing plant productivity. One of the earliest responses of plants to stress is a rapid burst of reactive oxygen species (ROS) in chloroplasts. Widespread efforts over the past decade shed new light on the chloroplast as an environmental sensor, translating the environmental fluctuation into varying physiological responses by utilizing distinct retrograde (chloroplast-to-nucleus) signals. Recent studies have unveiled that chloroplasts mediate a similar unfolded/misfolded/damaged protein response (cpUPR) as observed in the endoplasmic reticulum and mitochondria. Although observing cpUPR is not surprising since the chloroplast is a prime organelle producing harmful ROS, the intertwined relationship among ROS, protein damage, and chloroplast protein quality controls (cpPQCs) with retrograde signaling has recently been reported. This finding also gives rise to critical attention on chloroplast proteins involved in cpPQCs, ROS detoxifiers, transcription/translation, import of precursor proteins, and assembly/maturation, the deficiency of which compromises chloroplast protein homeostasis (proteostasis). Any perturbation in the protein may require readjustment of proteostasis by transmitting retrograde signal(s) to the nucleus, whose genome encodes most of the chloroplast proteins involved in proteostasis. This review focuses on recent findings on cpUPR and chloroplast-targeted FILAMENTOUS TEMPERATURE-SENSITIVE H proteases involved in cpPQC and retrograde signaling and their impacts on plant responses to temperature stress.
低温和高温是危及生命的应激因素，会降低植物的生产力。植物对胁迫的最早反应之一是叶绿体中活性氧（ROS）的快速爆发。在过去十年中，广泛的研究工作揭示了叶绿体作为环境传感器的新作用，通过利用独特的逆行（叶绿体到细胞核）信号，将环境波动转化为不同的生理反应。最近的研究表明，叶绿体介导了类似于内质网和线粒体中观察到的未折叠/错误折叠/受损蛋白反应（cpUPR）。虽然观察到 cpUPR 并不奇怪，因为叶绿体是产生有害 ROS 的主要细胞器，但 ROS、蛋白损伤和与逆行信号相关的叶绿体蛋白质量控制（cpPQCs）之间的交织关系最近才被报道。这一发现也引起了人们对参与 cpPQCs、ROS 解毒剂、转录/翻译、前体蛋白的导入以及组装/成熟的叶绿体蛋白的关注，这些蛋白的缺乏会损害叶绿体蛋白的稳态（蛋白质平衡）。任何蛋白质的扰动都可能需要通过向细胞核传递逆行信号来重新调整蛋白质平衡，细胞核的基因组编码了大多数参与蛋白质稳态的叶绿体蛋白。本综述重点介绍了最近关于 cpUPR 和参与 cpPQC 和逆行信号的叶绿体靶向 FILAMENTOUS TEMPERATURE-SENSITIVE H 蛋白酶的发现，以及它们对植物对温度胁迫反应的影响。
