Redox-mediated kick-start of mitochondrial energy metabolism drives resource-efficient seed germination
Redox-mediated kick-start of mitochondrial energy metabolism drives resource-efficient seed germination
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DOI：
10.1073/pnas.1910501117
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发表时间：
2020-01-07
影响因子：
11.1
通讯作者：
Schwarzlaender, Markus
中科院分区：
文献类型：
--
作者：
Nietzel, Thomas;Mostertz, Joerg;Schwarzlaender, Markus
种子使发育较远的植物胚胎处于静止状态。种子代谢依赖于储存的资源，并在外部条件有利时重新激活以驱动发芽。由于从静止到再激活的转换是细胞生理转变的一个显著案例，我们研究了拟南芥种子在吸胀时能量和氧化还原代谢的最早事件。通过对完整种子进行荧光蛋白生物传感，我们在几分钟内观察到ATP的积累和氧的摄取，表明线粒体呼吸的快速激活，这与线粒体基质从氧化到还原性更强的硫醇氧化还原环境的急剧转变相吻合。为了确定单个操作蛋白硫醇开关，我们捕获了细胞器中代谢静止的快速释放，并设计了基于碘乙酰串联质量标签（iodoTMT）的定量硫醇氧化还原蛋白质组学。所有Cys肽的氧化还原状态从27.1%下降到13.0%的氧化硫醇。大量的Cys肽（412）是氧化还原开关的，代表了线粒体能量代谢的中心途径，包括呼吸链和三羧酸（TCA）循环的每个酶促步骤。活性位点谷胱甘肽还原酶2、nadph -硫氧还蛋白还原酶a/b和硫氧还蛋白- 01的Cys肽反应最强。缺乏这些氧化还原蛋白的种子萌发与呼吸显著增强和TCA循环动力学解除相关，表明能量代谢资源效率降低。老化种子的萌发受到严重损害。我们确定了硫醇氧化还原开关的全局操作，这是线粒体最佳利用能量存储来驱动有效发芽所必需的。
Seeds preserve a far developed plant embryo in a quiescent state. Seed metabolism relies on stored resources and is reactivated to drive germination when the external conditions are favorable. Since the switchover from quiescence to reactivation provides a remarkable case of a cell physiological transition we investigated the earliest events in energy and redox metabolism of Arabidopsis seeds at imbibition. By developing fluorescent protein biosensing in intact seeds, we observed ATP accumulation and oxygen uptake within minutes, indicating rapid activation of mitochondrial respiration, which coincided with a sharp transition from an oxidizing to a more reducing thiol redox environment in the mitochondrial matrix. To identify individual operational protein thiol switches, we captured the fast release of metabolic quiescence in organello and devised quantitative iodoacetyl tandem mass tag (iodoTMT)-based thiol redox proteomics. The redox state across all Cys peptides was shifted toward reduction from 27.1% down to 13.0% oxidized thiol. A large number of Cys peptides (412) were redox switched, representing central pathways of mitochondrial energy metabolism, including the respiratory chain and each enzymatic step of the tricarboxylic acid (TCA) cycle. Active site Cys peptides of glutathione reductase 2, NADPH-thioredoxin reductase a/b, and thioredoxin-o1 showed the strongest responses. Germination of seeds lacking those redox proteins was associated with markedly enhanced respiration and deregulated TCA cycle dynamics suggesting decreased resource efficiency of energy metabolism. Germination in aged seeds was strongly impaired. We identify a global operation of thiol redox switches that is required for optimal usage of energy stores by the mitochondria to drive efficient germination.