RHON1 Mediates a Rho-Like Activity for Transcription Termination in Plastids of Arabidopsis thaliana
RHON1 Mediates a Rho-Like Activity for Transcription Termination in Plastids of Arabidopsis thaliana
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DOI：
10.1105/tpc.114.132118
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发表时间：
2014-12-01
期刊：
影响因子：
11.6
通讯作者：
Zhang, Lixin
中科院分区：
文献类型：
--
作者：
Chi, Wei;He, Baoye;Zhang, Lixin
虽然转录终止是产生功能性RNA所必需的，但其潜在的分子机制在维管植物质体中仍然知之甚少。在这里，我们表明，RNA结合蛋白RHON 1参与转录终止rbcL（编码大亚基的核酮糖-1，5-二磷酸羧化酶/加氧酶）在拟南芥。RHON 1的失活导致增强的rbcL通读转录和异常的accD（编码乙酰辅酶A羧化酶的β亚基）转录起始，这可能是由于rbcL的转录终止效率低下。RHON 1可以与rbcL的mRNA和单链DNA结合，显示RNA依赖的ATP酶活性，并在体外终止rbcL的转录。这些结果表明，RHON 1终止rbcL转录使用ATP驱动的机制类似于大肠杆菌的Rho。这种RHON 1依赖的转录终止发生在拟南芥中，而不是在水稻（水稻），似乎反映了双子叶和单子叶植物的质体之间的根本差异。我们的研究结果指出了质体转录终止的重要性和意义，并在进化背景下对其机制提供了见解。
Although transcription termination is essential to generate functional RNAs, its underlying molecular mechanisms are still poorly understood in plastids of vascular plants. Here, we show that the RNA binding protein RHON1 participates in transcriptional termination of rbcL (encoding large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase) in Arabidopsis thaliana. Inactivation of RHON1 leads to enhanced rbcL read-through transcription and to aberrant accD (encoding beta-subunit of the acetyl-CoA carboxylase) transcriptional initiation, which may result from inefficient transcription termination of rbcL. RHON1 can bind to the mRNA as well as to single-stranded DNA of rbcL, displays an RNA-dependent ATPase activity, and terminates transcription of rbcL in vitro. These results suggest that RHON1 terminates rbcL transcription using an ATP-driven mechanism similar to that of Rho of Escherichia coli. This RHON1-dependent transcription termination occurs in Arabidopsis but not in rice (Oryza sativa) and appears to reflect a fundamental difference between plastomes of dicotyledonous and monocotyledonous plants. Our results point to the importance and significance of plastid transcription termination and provide insights into its machinery in an evolutionary context.