Two distinct SECIS structures capable of directing selenocysteine incorporation in eukaryotes
Two distinct SECIS structures capable of directing selenocysteine incorporation in eukaryotes
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DOI：
10.1017/s1355838299981542
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发表时间：
1999-05-01
期刊：
影响因子：
4.5
通讯作者：
Berry, MJ
中科院分区：
文献类型：
--
作者：
Grundner-Culemann, E;Martin, GW;Berry, MJ
UGA翻译为硒代半胱氨酸需要硒蛋白mRNA中特定的RNA二级结构。这些元件在原核生物、真核生物和古细菌中的序列、结构和mRNA中的位置不同，即编码区与3'非翻译区不同。通过计算机折叠程序，诱变研究，和化学和酶的探测分析真核硒代半胱氨酸插入序列（SECIS）的元素，导致这些元素的预测共识结构模型的推导。该模型由茎环或发夹组成，在环中和茎基部的非沃森-克里克基序中具有保守的核苷酸。然而，许多SECIS元件的序列预测它们将偏离环区域中的共有结构。使用定点诱变引入突变预测破坏或恢复结构，或操纵环的大小或茎长，我们表明，真核SECIS元素分为两个不同的类，称为形式1和2。2型元件具有1型元件中不存在的额外二级结构。通过插入或删除区分两类元件的序列和结构，同时保持适当的环大小，实现了1型元件向功能性形式P样元件的转化和2型元件向功能性形式1样元件的转化。这些结果表明，两类的功能的共性。关于两类SECIS元件的存在和对茎长度和环大小的操纵的耐受性所获得的信息应有助于设计用于获得关于这些元件的高分辨率结构信息的RNA分子。
Translation of UGA as selenocysteine requires specific RNA secondary structures in the mRNAs of selenoproteins. These elements differ in sequence, structure, and location in the mRNA, that is, coding versus 3' untranslated region, in prokaryotes, eukaryotes, and archaea. Analyses of eukaryotic selenocysteine insertion Sequence (SECIS) elements via computer folding programs, mutagenesis studies, and chemical and enzymatic probing has led to the derivation of a predicted consensus structural model for these elements. This model consists of a stem-loop or hairpin, with conserved nucleotides in the loop and in a non-Watson-Crick motif at the base of the stem. However, the sequences of a number of SECIS elements predict that they would diverge from the consensus structure in the loop region. Using site-directed mutagenesis to introduce mutations predicted to either disrupt or restore structure, or to manipulate loop size or stem length, we show that eukaryotic SECIS elements fall into two distinct classes, termed forms 1 and 2. Form 2 elements have additional secondary structures not present in form 1 elements. By either insertion or deletion of the sequences and structures distinguishing the two classes of elements while maintaining appropriate loop size, conversion of a form 1 element to a functional form P-like element and of a form 2 to a functional form 1-like element was achieved. These results suggest commonality of function of the two classes. The information obtained regarding the existence of two classes of SECIS elements and the tolerances for manipulations of stem length and loop size should facilitate designing RNA molecules for obtaining high-resolution structural information about these elements.