GENE FOR A NOVEL TRANSFER-RNA SPECIES THAT ACCEPTS L-SERINE AND COTRANSLATIONALLY INSERTS SELENOCYSTEINE
GENE FOR A NOVEL TRANSFER-RNA SPECIES THAT ACCEPTS L-SERINE AND COTRANSLATIONALLY INSERTS SELENOCYSTEINE
复制标题
DOI：
10.1038/331723a0
复制
发表时间：
1988-02-25
期刊：
影响因子：
64.8
通讯作者：
BOCK, A
中科院分区：
文献类型：
--
作者：
LEINFELDER, W;ZEHELEIN, E;BOCK, A
40年前，人们就认识到了微量元素硒的生物学需求。硒被结合到几种酶中，并转移原核生物和真核生物来源的RNA物种。在含有硒多肽的酶中，硒以共价结合的硒半胱氨酸的形式存在，参与催化反应3。对大肠杆菌4的甲酸脱氢酶H和鼠5和MAN 6的谷胱甘肽过氧化物酶两种硒蛋白编码基因的序列分析表明，UGA蛋白下面的无义密码子指导着硒半胱氨酸的掺入。在甲酸脱氢酶的情况下，共翻译7。最近，我们在E.coli8中鉴定了四个基因，它们的产物是硒半胱氨酸掺入所必需的。我们在此报告其中一个基因编码具有独特性质的tRNA物种。它具有与UGA互补的反密码子，并在几个位置偏离序列，到目前为止，它在所有tRNA物种9‘10中被认为是不变的。该tRNA被丝氨酰-tRNA连接酶与L-丝氨酸酰化，该连接酶也负责同源的tRNAer。因此，硒半胱氨酸是由与识别UGA的天然抑制物tRNA结合的丝氨酸残基合成的。
The biological requirement of the trace element selenium was recognized 40 years ago1. Selenium is incorporated into several enzymes and transfer RNA species of both prokaryotic and eukaryotic origin2. In enzymes which contain a selenopolypeptide, selenium is present as covalently bound selenocysteine which participates in the catalytic reaction3. Sequence analysis of the genes coding for two selenoproteins, formate dehydrogenase H from Escherichia coli4and glutathione peroxidase from mouse5and man6, demonstrated that an inframe UGA opal nonsense codon directs the incorporation of selenocysteine. In the case of formate dehydrogenase incorporation occurs cotranslationally7. Recently, we identified four genes whose products are required for selenocysteine incorporation in E. coli8. We report here that one of these genes codes for a tRNA species with unique properties. It possesses an anticodon complementary to UGA and deviates in several positions from sequences, until now, considered invariant in all tRNA species9'10. This tRNA is aminoacylated with L-serine by the seryl-tRNA ligase which also charges cognate tRNASer. Selenocysteine, therefore, is synthesized from a serine residue bound to a natural suppressor tRNA which recognizes UGA.