A recoding element that stimulates decoding of UGA codons by Sec tRNA[Ser]Sec
A recoding element that stimulates decoding of UGA codons by Sec tRNA[Ser]Sec
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DOI：
10.1261/rna.473907
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发表时间：
2007-06-01
期刊：
影响因子：
4.5
通讯作者：
Anderson, Christine B.
中科院分区：
文献类型：
--
作者：
Howard, Michael T.;Moyle, Mark W.;Anderson, Christine B.
在真核生物硒蛋白mRNA的解码过程中，硒代半胱氨酸的插入需要几个反式作用因子和一个通常位于39 UTR的顺式作用硒代半胱氨酸插入序列（SECIS）。第二顺式作用硒代半胱氨酸密码子重定义元件（SRE）最近已被描述，其位于硒蛋白N（SEPN 1）的UGA-Sec密码子附近。在真核生物硒蛋白mRNA的一个子集中可以预测类似的遗传保守元件。先前对SEPN 1 SRE的实验分析揭示了它对UGA-Sec密码子的通读具有刺激作用，这不依赖于39 UTR中SECIS元件的存在;尽管如预期的那样，通过包含SECIS进一步提高了通读效率。为了研究SEPN 1 SRE刺激的重定义事件的性质，我们修改了一个实验上易于处理的体外翻译系统，该系统概括了有效的硒代半胱氨酸插入。这里呈现的结果说明SRE元件对由Sec tRNA（[Ser]Sec）的甲基化和未甲基化同种型解码UGA-Sec密码子具有刺激作用，并且证实有效的硒代半胱氨酸插入依赖于3 '-UTR SECIS的存在。UGA-Sec密码子附近预测的重编码元件的变化意味着这些元件可能在确定作为UGA解码效率的控制器产生的硒蛋白的量方面发挥不同的作用。
Selenocysteine insertion during decoding of eukaryotic selenoprotein mRNA requires several trans-acting factors and a cis-acting selenocysteine insertion sequence (SECIS) usually located in the 39 UTR. A second cis-acting selenocysteine codon redefinition element (SRE) has recently been described that resides near the UGA-Sec codon of selenoprotein N (SEPN1). Similar phylogenetically conserved elements can be predicted in a subset of eukaryotic selenoprotein mRNAs. Previous experimental analysis of the SEPN1 SRE revealed it to have a stimulatory effect on readthrough of the UGA-Sec codon, which was not dependent upon the presence of a SECIS element in the 39 UTR; although, as expected, readthrough efficiency was further elevated by inclusion of a SECIS. In order to examine the nature of the redefinition event stimulated by the SEPN1 SRE, we have modified an experimentally tractable in vitro translation system that recapitulates efficient selenocysteine insertion. The results presented here illustrate that the SRE element has a stimulatory effect on decoding of the UGA-Sec codon by both the methylated and unmethylated isoforms of Sec tRNA([Ser]Sec), and confirm that efficient selenocysteine insertion is dependent on the presence of a 3'-UTR SECIS. The variation in recoding elements predicted near UGA-Sec codons implies that these elements may play a differential role in determining the amount of selenoprotein produced by acting as controllers of UGA decoding efficiency.