Structure of the 5' untranslated regulatory region of ferritin mRNA studied in solution.
Structure of the 5' untranslated regulatory region of ferritin mRNA studied in solution.
复制标题
在溶液中研究铁蛋白 mRNA 5 非翻译调节区的结构。
DOI：
10.1093/nar/18.15.4463
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发表时间：
1990
影响因子：
14.9
通讯作者：
Theil,EC
中科院分区：
文献类型：
--
作者：
Wang,YH;Sczekan,SR;Theil,EC
铁蛋白 mRNA 是第一个已鉴定出保守翻译调控序列的真核 mRNA。 28 个核苷酸的序列称为 IRE（铁调节元件），位于 5'-非编码区，是过量细胞铁增强铁蛋白 mRNA 翻译所必需的；监管发生在启动时。 IRE中二级结构的预测是发夹环。我们现在报道了对天然铁蛋白 mRNA [H 和 H'(M) 亚基] 溶液中 IRE 结构的分析，通过引物延伸，经过硫酸二甲酯、RNAase T1 和 V1 以及化学核酸酶 1,10-菲咯啉-铜 (OPCu) 的修饰或切割后，该酶可切割 RNA 的单链和凸出区域。总体而言，铁蛋白mRNA调节区溶液中的结构是发夹环，具有镁敏感特征，其中一半茎由IRE提供，一半由侧翼区域提供；侧翼区域仅保留二级结构。 OPCu 可以清楚地检测到沿茎预测的凸起或内部环，但体积更大的探针 RNAase T1 却无法检测到；表明 OPCu 在探测 RNA 结构的微妙特征方面的功效。在发夹环和 C6 凸起之间的茎中观察到与预测结构的镁依赖性偏差。 IRE 相对于起始子 AUG 或帽的位置在不同的铁蛋白 mRNA 中是可变的。然而，已知铁蛋白 mRNA 的碱基配对侧翼区域中的核苷酸数量与 IRE 与帽子的距离成正比，并将二级/三级结构放置在距帽子 8 – 10 个核苷酸的位置，其中可能干扰起始。
Ferritin mRNAs are the first eukaryotic mRNAs for which a conserved, translational regulatory sequence has been identified. The sequence of twenty-eight nucleotides, called the IRE (iron regulatory element), is found in the 5'-noncoding region and is required for enhanced translation of ferritin mRNA by excess cellular iron; regulation occurs at initiation. The prediction of secondary structure in the IRE is a hairpin loop. We now report an analysis of the IRE structure in solution studied in natural ferritin mRNAs [H and H'(M) subunits] by primer extension, after modification or cleavage by dimethyl sulfate, RNAases T1and V1, and the chemical nuclease 1,10-phenanthroline-copper (OPCu) which cleaves single-stranded and bulged regions of RNA. Overall, the structure in solution of the ferritin mRNA regulatory region is a hairpin loop, with magnesium-sensitive features, in which half the stem is provided by the IRE and half by flanking regions; only secondary structure is conserved in the flanking regions. Predicted bulges or internal loops along the stem were clearly detected by OPCu but were missed by the more bulky probe RNAase T1; indicating the efficacy of OPCu in probing subtle features of RNA structure. Magnesium-dependent deviations from the predicted structure were observed in the stem between the hairpin loop and the bulge at C6. The location of the IRE in relation to the initiator AUG or the cap is variable in different ferritin mRNAs. However, the number of nucleotides in the base-paired flanking regions of known ferritin mRNAs is proportional to the distance of the IRE from the cap and places the secondary/tertiary structure 8 – 10 nucleotides from the cap where interference with initiation is likely.