Arabidopsis tRNA Adenosine Deaminase Arginine Edits the Wobble Nucleotide of Chloroplast tRNAArg(ACG) and Is Essential for Efficient Chloroplast Translation
Arabidopsis tRNA Adenosine Deaminase Arginine Edits the Wobble Nucleotide of Chloroplast tRNAArg(ACG) and Is Essential for Efficient Chloroplast Translation
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DOI：
10.1105/tpc.109.066654
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发表时间：
2009-07-01
期刊：
影响因子：
11.6
通讯作者：
Gualberto, Jose M.
中科院分区：
文献类型：
--
作者：
Delannoy, Etienne;Le Ret, Monique;Gualberto, Jose M.
RNA 编辑通过核苷酸插入、删除或转换来改变转录物传递的编码/解码信息。真核生物和原核生物都使用通过将腺嘌呤脱氨基为肌苷来编辑 tRNA 反密码子来扩展单个 tRNA 的解码能力。这限制了密码子-反密码子识别所需的 tRNA 种类的数量。我们已经鉴定出拟南芥基因编码 tRNA 腺苷脱氨酶精氨酸 (TADA)，这是一种叶绿体 tRNA 编辑蛋白，是叶绿体 (cp)-tRNA(Arg)(ACG) 脱氨基为 cp-tRNA(Arg)(ICG) 所必需的。陆地植物 TADA 具有与原核 tRNA 脱氨酶序列和预测结构相似的 C 端结构域，并且还具有来源和功能未知的非常长的 N 端延伸。生化和突变体互补研究表明，C 末端结构域足以在体外和植物中进行同源 tRNA 脱氨基。 TADA 的破坏对叶绿体翻译效率具有深远影响，导致叶绿体编码蛋白质的产量减少和光合作用功能受损。相比之下，叶绿体转录物积累的水平明显高于野生型植物。然而，cp-tRNA(Arg)(ICG) 的缺失与植物的生存是相容的，这意味着三分之二的 CGN 密码子识别发生在叶绿体中，尽管这种机制的效率低于摆动配对。
RNA editing changes the coding/decoding information relayed by transcripts via nucleotide insertion, deletion, or conversion. Editing of tRNA anticodons by deamination of adenine to inosine is used both by eukaryotes and prokaryotes to expand the decoding capacity of individual tRNAs. This limits the number of tRNA species required for codon-anticodon recognition. We have identified the Arabidopsis thaliana gene that codes for tRNA adenosine deaminase arginine (TADA), a chloroplast tRNA editing protein specifically required for deamination of chloroplast (cp)-tRNA(Arg)(ACG) to cp-tRNA(Arg)(ICG). Land plant TADAs have a C-terminal domain similar in sequence and predicted structure to prokaryotic tRNA deaminases and also have very long N-terminal extensions of unknown origin and function. Biochemical and mutant complementation studies showed that the C-terminal domain is sufficient for cognate tRNA deamination both in vitro and in planta. Disruption of TADA has profound effects on chloroplast translation efficiency, leading to reduced yields of chloroplast-encoded proteins and impaired photosynthetic function. By contrast, chloroplast transcripts accumulate to levels significantly above those of wild-type plants. Nevertheless, absence of cp-tRNA(Arg)(ICG) is compatible with plant survival, implying that two out of three CGN codon recognition occurs in chloroplasts, though this mechanism is less efficient than wobble pairing.