The chloroplast protein BPG2 functions in brassinosteroid-mediated post-transcriptional accumulation of chloroplast rRNA
The chloroplast protein BPG2 functions in brassinosteroid-mediated post-transcriptional accumulation of chloroplast rRNA
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DOI：
10.1111/j.1365-313x.2009.04077.x
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发表时间：
2010-02-01
期刊：
影响因子：
7.2
通讯作者：
Nakano, Takeshi
中科院分区：
文献类型：
--
作者：
Komatsu, Tomoyuki;Kawaide, Hiroshi;Nakano, Takeshi
油菜素内酯类化合物（brassinosteroids，BRs）是植物器官和叶绿体发育的重要调控因子。我们鉴定了一个隐性的浅绿色拟南芥突变体bpg 2 -1（Brz-不敏感-浅绿色2-1），该突变体在光照下对Brz促进的叶绿素积累的敏感性降低。BPG 2编码一个叶绿体定位的蛋白质，具有锌指基序和四个正常叶绿体生物发生所必需的GTP结合结构域。BPG 2同源基因在植物、绿色藻类和细菌中进化保守。BPG 2的表达由光和Brz诱导。bpg 2 -1突变体的叶绿体中基粒类囊体的堆积数量减少。在bpg 2 -1和bpg 2 -2突变体中，rbcL和psbA的表达没有减少，但叶绿体16 S和23 SrRNA前体的异常积累。bpg 2突变体抑制Brz诱导的叶绿体蛋白质积累。这些结果表明，BPG 2在叶绿体中的转录后和翻译调控中起重要作用，并且是BR信号传导的组分。
Brassinazole (Brz) is a specific inhibitor of the biosynthesis of brassinosteroids (BRs), which regulate plant organ and chloroplast development. We identified a recessive pale green Arabidopsis mutant, bpg2-1 (Brz-insensitive-pale green 2-1) that showed reduced sensitivity to chlorophyll accumulation promoted by Brz in the light. BPG2 encodes a chloroplast-localized protein with a zinc finger motif and four GTP-binding domains that are necessary for normal chloroplast biogenesis. BPG2-homologous genes are evolutionally conserved in plants, green algae and bacteria. Expression of BPG2 is induced by light and Brz. Chloroplasts of the bpg2-1 mutant have a decreased number of stacked grana thylakoids. In bpg2-1 and bpg2-2 mutants, there was no reduction in expression of rbcL and psbA, but there was abnormal accumulation of precursors of chloroplast 16S and 23S rRNA. Chloroplast protein accumulation induced by Brz was suppressed by the bpg2 mutation. These results indicate that BPG2 plays an important role in post-transcriptional and translational regulation in the chloroplast, and is a component of BR signaling.