The nature of the minimal 'selenocysteine insertion sequence' (SECIS) in Escherichia coli
The nature of the minimal 'selenocysteine insertion sequence' (SECIS) in Escherichia coli
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DOI：
10.1093/nar/26.4.896
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发表时间：
1998-02-15
影响因子：
14.9
通讯作者：
Engelberg-Kulka, H
中科院分区：
文献类型：
--
作者：
Liu, ZS;Reches, M;Engelberg-Kulka, H
UGA密码子，通常是终止密码子，也可以指导修饰的氨基酸硒代半胱氨酸掺入蛋白质中。该UGA解码过程需要称为“硒代半胱氨酸插入序列”(SECIS)的顺式作用mRNA元件，其可以形成茎环结构。在大肠杆菌中，硒蛋白甲酸脱氢酶 (FdhH) mRNA 的 SECIS 先前已被描述为由 UGA 密码子之后的至少 40 个核苷酸组成。在这里，我们确定了大肠杆菌体内 UGA 引导的硒代半胱氨酸掺入所需的最小 SECIS 的性质。我们的研究基于对 lac'Z 融合体中的 fdhF SECIS DNA 的广泛突变分析。我们发现之前描述的大肠杆菌fdhF SECIS的整个茎环RNA结构对于UGA引导的体内硒代半胱氨酸掺入来说不是必需的，相反，只有其上部的17个核苷酸的茎环结构是必需的，条件是它与UGA密码子有适当的距离（11个核苷酸）。基于这些观察，我们提出了最小大肠杆菌SECIS的新模型。
The UGA codon, usually a stop codon, can also direct the incorporation into a protein of the modified amino acid selenocysteine, This UGA decoding process requires a cis-acting mRNA element called 'seleno-cysteine insertion sequence' (SECIS) that can form a stem-loop structure. In Escherichia coli the SECIS of the selenoprotein formate dehydrogenase (FdhH) mRNA has been previously described to consist of at least 40 nucleotides following the UGA codon, Here we determined the nature of the minimal SECIS required for the in vivo UGA-directed selenocysteine incorporation in E.coli, Our study is based on extensive mutational analysis of the fdhF SECIS DNA located in a lac'Z fusion. We found that the whole stem-loop RNA structure of the E.coli fdhF SECIS previously described is not required for the UGA-directed selenocysteine incorporation in vivo, Rather, only its upper stem-loop structure of 17 nucleotides is necessary on the condition that it is located in a proper distance (11 nucleotides) from the UGA codon, Based on these observations, we present a new model for the minimal E.coli SECIS.