Non-AUG translation initiation of mRNA encoding plastid-targeted phage-type RNA polymerase in Nicotiana sylvestris
Non-AUG translation initiation of mRNA encoding plastid-targeted phage-type RNA polymerase in Nicotiana sylvestris
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DOI：
10.1016/s0006-291x(02)02579-2
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发表时间：
2002-11-22
影响因子：
3.1
通讯作者：
Sugita, M
中科院分区：
文献类型：
--
作者：
Kobayashi, Y;Dokiya, Y;Sugita, M
从烟叶中分离到编码噬菌体t7型RNA聚合酶的第三个核基因NsRpoT-C，并对其进行了鉴定。该基因名为NsRpoT-C，由21个外显子和20个内含子组成，编码977个氨基酸残基的多肽。预测的NsRpoT-C蛋白与拟南芥RpoT的同源性最高（72%的氨基酸同源性）；它是一种针对质体的蛋白质。令人惊讶的是，推导出的NsRpoT-C氨基酸序列与拟南芥RpoT的比较；3预测NsRpoT-C从一个罕见的翻译起始密码子CUG三联体开始。在烟叶原生质体中的瞬时表达实验表明，NsRpoT-C的n端转运肽编码一个靶向信号，将该蛋白引导到叶绿体中。这强烈表明NsRpoT-C作为转录质体编码基因的RNA聚合酶起作用。我们将这个蛋白命名为NsRpoTp。(C) 2002 Elsevier Science （USA）。版权所有。
A third nuclear gene encoding a bacteriophage T7-type RNA polymerase, NsRpoT-C, was isolated and characterized from Nicotiana sylvestris. The gene, NsRpoT-C, consists of 21 exons and 20 introns and encodes a polypeptide of 977 amino acid residues. The predicted NsRpoT-C protein shows the highest identity (72% amino acid identity) with Arabidopsis thaliana RpoT;3 which is a plastid-targeted protein. Surprisingly, comparison of the deduced amino acid sequence of NsRpoT-C with that of A. thaliana RpoT;3 predicted that the NsRpoT-C starts at a CUG triplet, a rare translation initiation codon. Transient expression assays in protoplasts from tobacco leaves demonstrated that the putative N-terminal transit peptide of NsRpoT-C encodes a targeting signal directing the protein into chloroplasts. This strongly suggests that NsRpoT-C functions as an RNA polymerase transcribing plastid-encoded genes. We have designated this protein NsRpoTp. (C) 2002 Elsevier Science (USA). All rights reserved.