Selenocysteine incorporation in eukaryotes: insights into mechanism and efficiency from sequence, structure, and spacing proximity studies of the type 1 deiodinase SECIS element.
Selenocysteine incorporation in eukaryotes: insights into mechanism and efficiency from sequence, structure, and spacing proximity studies of the type 1 deiodinase SECIS element.
复制标题
DOI：
--
复制
发表时间：
1996-02
期刊：
影响因子：
4.5
通讯作者：
G. W. Martin;J. Harney;M. Berry
中科院分区：
文献类型：
--
作者：
G. W. Martin;J. Harney;M. Berry
SECIS 元件是位于真核硒蛋白 mRNA 3' 非翻译区 (UTR) 的茎环结构，是指导共翻译硒代半胱氨酸掺入 UGA 密码子所必需的。在原核生物中，介导硒代半胱氨酸掺入的茎环紧邻编码区中 UGA 硒代半胱氨酸密码子的下游。先前对 1 型脱碘酶、谷胱甘肽过氧化物酶和硒蛋白 P 的哺乳动物 SECIS 元件的表征研究表明，环和不配对凸起中的保守核苷酸以及茎中的碱基配对是 SECIS 功能所必需的。这些初步研究利用了硒蛋白 mRNA 3'UTR 的大约 175-230-nt 片段。在这里，我们定义了最小功能性大鼠 1 型脱碘酶 SECIS 元件，这是一个 45-nt 片段，其 5' 边界精确对应于先前确定的 5'-最关键保守核苷酸。我们还在该元素的主干中定义了碱基配对要求。鉴于细菌硒蛋白的开放阅读框（ORF）中存在 SECIS 元件，我们检查了 1 型脱碘酶将 ORF 延伸到 SECIS 元件的效果，发现这显着抑制了 SECIS 功能。最后，我们定义了真核 UGA 硒代半胱氨酸密码子和 SECIS 元件之间 51-111 nt 的最小间距要求。
SECIS elements are stem-loop structures located in the 3' untranslated regions (UTRs) of eukaryotic selenoprotein mRNAs that are required for directing cotranslational selenocysteine incorporation at UGA codons. In prokaryotes, stem-loops mediating selenocysteine incorporation are located immediately downstream of the UGA selenocysteine codon, in the coding region. Previous characterization studies of the mammalian SECIS elements of type 1 deiodinase, glutathione peroxidase, and selenoprotein P showed that conserved nucleotides in the loops and unpaired bulges, and base pairing in the stems are required for SECIS function. These initial studies utilized approximately 175-230-nt segments of the 3'UTRs of the selenoprotein mRNAs. Here we define the minimal functional rat type 1 deiodinase SECIS element, a 45-nt segment, the 5' boundary of which corresponds precisely to the 5'-most critical conserved nucleotide identified previously. We also define base pairing requirements in the stem of this element. In view of the presence of SECIS elements in the open reading frames (ORFs) of bacterial selenoproteins, we examine the effects in the type 1 deiodinase of extending the ORF into the SECIS element, and find that this dramatically inhibits SECIS function. Finally, we define a minimal spacing requirement of 51-111 nt between a eukaryotic UGA selenocysteine codon and SECIS element.