A Point Mutation in the Pentatricopeptide repeat Motif of the AtECB2 Protein Causes Delayed Chloroplast Development
A Point Mutation in the Pentatricopeptide repeat Motif of the AtECB2 Protein Causes Delayed Chloroplast Development
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DOI：
10.1111/j.1744-7909.2011.01030.x
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发表时间：
2011-04-01
影响因子：
11.4
通讯作者：
Yang, Zhong-Nan
中科院分区：
文献类型：
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作者：
Cao, Zhi-Lin;Yu, Qing-Bo;Yang, Zhong-Nan
AtECB 2编码一个五肽重复序列（PPR）蛋白，该蛋白调节质体基因accD和ndhF的编辑。ecb 2 -1基因敲除显示出白化病表型，并且是幼苗致死的。在这项研究中，我们分离出一个等位基因突变体的AtECB 2基因，ecb 2 -2，表现出延迟绿化表型，但可以完成其生命周期。在该突变体中，AtECB 2蛋白的第13个PPR基序中的Thr 500被转化为Ile 500。透射电子显微镜观察表明，突变体的子叶和叶片中叶绿体的发育都被延迟。叶绿体基因表达谱的调查表明，PEP（质体编码的RNA聚合酶）活性在ecb 2 -2子叶没有明显的影响，而它是严重受损ecb 2 -1。这一结果表明，PEP活性导致ecb 2 -1和ecb 2 -2突变体的不同表型。突变体中accD（C794和C1568）和ndhF（C290）三个编辑位点的编辑效率动态变化，与表型一致。该结果表明ecb 2 -2突变体中accD和ndhF的编辑效率与延迟的绿化表型相关。ecb 2 -2能够存活并结籽，可用于拟南芥RNA编辑和叶绿体发育的研究。
AtECB2 encodes a pentatricopeptide repeat (PPR) protein that regulates the editing of the plastid genes accD and ndhF. The ecb2-1 knockout shows an albino phenotype and is seedling lethal. In this study, we isolated an allelic mutant of the AtECB2 gene, ecb2-2, which showed delayed greening phenotype but could complete their life cycle. In this mutant, the Thr500 is converted to Ile500 in the 13th PPR motif of the AtECB2 protein. Transmission electron microscopy demonstrated that chloroplast development was delayed in both the cotyledons and leaves of the mutant. An investigation of the chloroplast gene expression profile indicated that PEP (plastid-encoded RNA polymerase) activity in ecb2-2 cotyledons was not obviously affected, whereas it was severely impaired in ecb2-1. This result suggests that the PEP activities cause the different phenotypes of the ecb2-1 and ecb2-2 mutants. The editing efficiency of the three editing sites of accD (C794 and C1568) and ndhF (C290) in the mutant was dynamically altered, which was in agreement with the phenotype. This result indicates that the editing efficiency of accD and ndhF in the ecb2-2 mutant is associated with a delayed greening phenotype. As ecb2-2 can survive and set seeds, this mutant can be used for further investigation of RNA editing and chloroplast development in arabidopsis.