Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, South Korea.
J Exp Bot. 2022 Sep 30;73(17):5863-5873. doi: 10.1093/jxb/erac002.
Physiological effects mediated by melatonin are attributable to its potent antioxidant activity as well as its role as a signaling molecule in inducing a vast array of melatonin-mediated genes. Here, we propose melatonin as a signaling molecule essential for protein quality control (PQC) in plants. PQC occurs by the coordinated activities of three systems: the chaperone network, autophagy, and the ubiquitin-proteasome system. With regard to the melatonin-mediated chaperone pathway, melatonin increases thermotolerance by induction of heat shock proteins and confers endoplasmic reticulum stress tolerance by increasing endoplasmic reticulum chaperone proteins. In chloroplasts, melatonin-induced chaperones, including Clps and CpHSP70s, play key roles in the PQC of chloroplast-localized proteins, such as Lhcb1, Lhcb4, and RBCL, during growth. Melatonin regulates PQC by autophagy processes, in which melatonin induces many autophagy (ATG) genes and autophagosome formation under stress conditions. Finally, melatonin-mediated plant stress tolerance is associated with up-regulation of stress-induced transcription factors, which are regulated by the ubiquitin-proteasome system. In this review, we propose that melatonin plays a pivotal role in PQC and consequently functions as a pleiotropic molecule under non-stress and adverse conditions in plants.
褪黑素介导的生理效应归因于其强大的抗氧化活性，以及作为信号分子诱导广泛的褪黑素介导基因的作用。在这里，我们提出褪黑素是植物蛋白质质量控制 (PQC) 所必需的信号分子。PQC 通过三个系统的协调活动来实现：伴侣蛋白网络、自噬和泛素-蛋白酶体系统。关于褪黑素介导的伴侣蛋白途径，褪黑素通过诱导热休克蛋白来提高耐热性，并通过增加内质网伴侣蛋白来赋予内质网应激耐受性。在叶绿体中，褪黑素诱导的伴侣蛋白，包括 Clps 和 CpHSP70s，在生长过程中对叶绿体定位蛋白（如 Lhcb1、Lhcb4 和 RBCL）的 PQC 中发挥关键作用。褪黑素通过自噬过程来调节 PQC，在应激条件下，褪黑素诱导许多自噬 (ATG) 基因和自噬体形成。最后，褪黑素介导的植物应激耐受性与应激诱导转录因子的上调有关，这些转录因子受泛素-蛋白酶体系统的调节。在这篇综述中，我们提出褪黑素在 PQC 中发挥关键作用，因此在植物的非胁迫和不利条件下作为一种多效分子发挥作用。
