State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
J Biol Chem. 2020 Jan 24;295(4):1036-1046. doi: 10.1074/jbc.RA119.011853. Epub 2019 Dec 13.
Chloroplast development and photosynthesis require the proper assembly and turnover of photosynthetic protein complexes. Chloroplasts harbor a repertoire of proteases to facilitate proteostasis and development. We have previously used an Arabidopsis leaf variegation mutant, (), defective in thylakoid FtsH protease complexes, as a tool to dissect the genetic regulation of chloroplast development. Here, we report a new genetic enhancer mutant of , (). We confirm that encodes a chloroplast metalloprotease, reported previously as ethylene-dependent gravitropism-deficient and yellow-green1 (EGY1)/ammonium overly sensitive1 (AMOS1). We observed that mutations in // cause more severe leaf variegation in and synthetic lethality in Using a modified blue-native PAGE system, we reveal abnormal accumulations of photosystem I, photosystem II, and light-harvesting antenna complexes in // mutants. Moreover, we discover distinct roles of VAR2 and EVR3/EGY1/AMOS1 in the turnover of photosystem II reaction center under high light stress. In summary, our findings indicate that two chloroplast metalloproteases, VAR2/AtFtsH2 and EVR3/EGY1/AMOS1, function coordinately to regulate chloroplast development and reveal new roles of EVR3/EGY1/AMOS1 in regulating chloroplast proteostasis in Arabidopsis.
叶绿体的发育和光合作用需要适当组装和周转光合蛋白复合物。叶绿体拥有一系列蛋白酶来促进蛋白质的稳定性和发育。我们之前曾使用拟南芥叶片斑驳突变体（），其类囊体 FtsH 蛋白酶复合物有缺陷，作为一种工具来解析叶绿体发育的遗传调控。在这里，我们报告了一个新的遗传增强突变体，（）。我们确认编码一个叶绿体金属蛋白酶，先前报道为乙烯依赖性向重力性缺陷和黄-绿 1（EGY1）/铵过度敏感 1（AMOS1）。我们观察到//中的突变导致在和合成致死性中更严重的叶片斑驳。使用改良的蓝色非变性 PAGE 系统，我们发现在//突变体中，光系统 I、光系统 II 和光捕获天线复合物的异常积累。此外，我们发现 VAR2 和 EVR3/EGY1/AMOS1 在高光胁迫下在光系统 II 反应中心的周转中具有不同的作用。总之，我们的发现表明两种叶绿体金属蛋白酶 VAR2/AtFtsH2 和 EVR3/EGY1/AMOS1 协同作用调节叶绿体发育，并揭示了 EVR3/EGY1/AMOS1 在调节拟南芥叶绿体蛋白质稳定性方面的新作用。
