Meulewaeter Frank, van Lipzig Rosalinde, Gultyaev Alexander P, Pleij Cornelis W A, Van Damme Daniel, Cornelissen Marc, van Eldik Gerben
Bayer BioScience N.V., J. Plateaustraat 22, B-9000, Gent, Belgium.
Nucleic Acids Res. 2004 Mar 12;32(5):1721-30. doi: 10.1093/nar/gkh338. Print 2004.
The subgenomic RNA 2 of tobacco necrosis virus A (TNV sgRNA2) encodes the viral coat protein, is unpolyadenylated and presumably uncapped. Here, we show that TNV sgRNA2 is translated cap independently. This cap-independent translation requires the leader and a 140 nt element of the trailer both in wheat germ extract and in tobacco protoplasts. Similar to barley yellow dwarf virus (BYDV), the TNV 5' and 3' elements stimulate translation synergistically. Computer-aided phylogenetic analysis of the secondary structure of the TNV trailer revealed that the 3' translation element is part of a major conserved stem-loop that contains similarities to structures in the BYDV 3' translation element. These data suggest that the translation mechanisms of TNV sgRNA2 and BYDV RNA are related. To further characterize this relationship, we tested whether cooperativity exists between TNV sgRNA2 and BYDV 5' and 3' elements. We found that the TNV sgRNA2 5' element stimulates translation synergistically with the BYDV 3' element in vitro. This finding is the first evidence for conservation of structures that enable a 5'-3' interaction stimulating cap-independent translation.
烟草坏死病毒A的亚基因组RNA 2（TNV sgRNA2）编码病毒外壳蛋白，无多聚腺苷酸化且可能无帽结构。在此，我们表明TNV sgRNA2的翻译不依赖帽结构。这种不依赖帽结构的翻译在小麦胚芽提取物和烟草原生质体中都需要前导序列和拖尾序列中的一个140 nt元件。与大麦黄矮病毒（BYDV）类似，TNV的5'和3'元件协同刺激翻译。对TNV拖尾序列二级结构的计算机辅助系统发育分析表明，3'翻译元件是一个主要保守茎环结构的一部分，该结构与BYDV 3'翻译元件中的结构有相似之处。这些数据表明TNV sgRNA2和BYDV RNA的翻译机制相关。为了进一步表征这种关系，我们测试了TNV sgRNA2与BYDV的5'和3'元件之间是否存在协同作用。我们发现TNV sgRNA2的5'元件在体外与BYDV的3'元件协同刺激翻译。这一发现是首次证明存在能够实现5'-3'相互作用以刺激不依赖帽结构翻译的保守结构。
