Thioredoxin Redox Regulates ATPase Activity of Magnesium Chelatase CHLI Subunit and Modulates Redox-Mediated Signaling in Tetrapyrrole Biosynthesis and Homeostasis of Reactive Oxygen Species in Pea Plants
Thioredoxin Redox Regulates ATPase Activity of Magnesium Chelatase CHLI Subunit and Modulates Redox-Mediated Signaling in Tetrapyrrole Biosynthesis and Homeostasis of Reactive Oxygen Species in Pea Plants
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硫氧还蛋白氧化还原调节镁螯合酶 CHLI 亚基的 ATP 酶活性并调节豌豆植物四吡咯生物合成和活性氧稳态中氧化还原介导的信号传导
DOI：
10.1104/pp.112.195446
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发表时间：
2012-05-01
期刊：
影响因子：
7.4
通讯作者：
Luo, Meizhong
中科院分区：
文献类型：
--
作者：
Luo, Tao;Fan, Tingting;Luo, Meizhong
叶绿体硫氧还蛋白（TRXs）作为氧化还原信号从铁氧还蛋白到靶酶的信使。本研究在体外和体内研究了豌豆TRX-F对镁螯合酶CHLI亚基和镁螯合酶活性的调控作用。在体外，减少TRX-F激活了豌豆CHLI的atp酶活性，并增强了由三个重组亚基CHLI、CHLD和CHLH结合调节蛋白基因组UNCOUPLED4 （GUN4）重组的Mg螯合酶的活性。酵母双杂交和双分子荧光互补实验表明，TRX-F与CHLI物理相互作用，但不与其他两个亚基或GUN4相互作用。在体内，豌豆植物中病毒诱导的TRX-F基因沉默（VIGS-TRX-F）不会导致CHLI氧化还原状态的改变。然而，同时沉默豌豆TRX-F和TRX-M基因（VIGS-TRX-F/TRX-M）导致体内部分和完全氧化的CHLI。VIGS-TRX-F/TRX-M植株的Mg螯合酶活性和5-氨基乙酰丙酸合成能力显著降低，色素含量降低，光合能力降低。这些结果表明，在体内，TRX-M可以弥补TRX-F的缺乏，并且这两种trx都是Mg螯合酶的重要氧化还原调节剂。此外，TRX-F和TRX-M表达的沉默也会影响四吡咯生物合成途径的基因表达，导致活性氧的积累，这也可能是光合作用相关核基因转录调控的额外信号。
The chloroplast thioredoxins (TRXs) function as messengers of redox signals from ferredoxin to target enzymes. In this work, we studied the regulatory impact of pea (Pisum sativum) TRX-F on the magnesium (Mg) chelatase CHLI subunit and the enzymatic activation of Mg chelatase in vitro and in vivo. In vitro, reduced TRX-F activated the ATPase activity of pea CHLI and enhanced the activity of Mg chelatase reconstituted from the three recombinant subunits CHLI, CHLD, and CHLH in combination with the regulator protein GENOMES UNCOUPLED4 (GUN4). Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that TRX-F physically interacts with CHLI but not with either of the other two subunits or GUN4. In vivo, virus-induced TRX-F gene silencing (VIGS-TRX-F) in pea plants did not result in an altered redox state of CHLI. However, simultaneous silencing of the pea TRX-F and TRX-M genes (VIGS-TRX-F/TRX-M) resulted in partially and fully oxidized CHLI in vivo. VIGS-TRX-F/TRX-M plants demonstrated a significant reduction in Mg chelatase activity and 5-aminolevulinic acid synthesizing capacity as well as reduced pigment content and lower photosynthetic capacity. These results suggest that, in vivo, TRX-M can compensate for a lack of TRX-F and that both TRXs act as important redox regulators of Mg chelatase. Furthermore, the silencing of TRX-F and TRX-M expression also affects gene expression in the tetrapyrrole biosynthesis pathway and leads to the accumulation of reactive oxygen species, which may also serve as an additional signal for the transcriptional regulation of photosynthesis-associated nuclear genes.