5′-3′ RNA-RNA interaction facilitates cap- and poly(A) tail-independent translation of tomato bushy stunt virus mRNA -: A potential common mechanism for Tombusviridae
5′-3′ RNA-RNA interaction facilitates cap- and poly(A) tail-independent translation of tomato bushy stunt virus mRNA -: A potential common mechanism for Tombusviridae
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DOI：
10.1074/jbc.m401272200
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发表时间：
2004-07-09
影响因子：
4.8
通讯作者：
White, KA
中科院分区：
文献类型：
--
作者：
Fabian, MR;White, KA
番茄浓密矮化病毒（TBSV）是番茄病毒科番茄病毒属的典型成员。 TBSV 的 (+)-链 RNA 基因组缺乏 5' 帽和 3' 聚腺苷酸尾，而是包含充当帽独立翻译增强子 (3' CITE) 的 3' 末端 RNA 序列。在这项研究中，我们确定了 3' CITE 翻译特异性中央片段的 RNA 二级结构，称为区域 3.5 (R3.5)。 MFOLD结构建模结合溶液结构作图和比较序列分析表明R3.5采用包含三个主要螺旋的支化结构。删除和取代研究表明，其中两个延伸的茎环 (SL) 结构对于体内 3' CITE 活性至关重要。特别是，这些 SL 之一（SL-B）的末端环被发现对于翻译至关重要。补偿突变分析表明，SL-B 通过与 TBSV 基因组 5' 非翻译区中的另一个 SL（SL3）碱基配对发挥作用。因此，TBSV mRNA在体内的有效翻译需要有效环化信息的5'-3'RNA-RNA相互作用。类似类型的相互作用也预计会发生在 TBSV 亚基因组 mRNA 的 5' 非翻译区和 3' CITE 之间，并且基因组和亚基因组 5'-3' 相互作用在 Tombusvirus 属的所有成员中都非常保守。此外，对 Tombusviridae 中其他属的调查揭示了其病毒 mRNA 中类似的基于 5'-3' RNA-RNA 的相互作用的潜力，表明这种机制延伸到了这个大病毒家族。
Tomato bushy stunt virus (TBSV) is the prototypical member of the genus Tombusvirus in the family Tombusviridae. The (+)-strand RNA genome of TBSV lacks both a 5' cap and a 3' poly( A) tail and instead contains a 3'-terminal RNA sequence that acts as a cap-independent translational enhancer (3' CITE). In this study, we have determined the RNA secondary structure of the translation-specific central segment of the 3' CITE, termed region 3.5 (R3.5). MFOLD structural modeling combined with solution structure mapping and comparative sequence analysis indicate that R3.5 adopts a branched structure that contains three major helices. Deletion and substitution studies revealed that two of these extended stem-loop (SL) structures are essential for 3' CITE activity in vivo. In particular, the terminal loop of one of these SLs, SL-B, was found to be critical for translation. Compensatory mutational analysis showed that SL-B functions by base pairing with another SL, SL3, in the 5' untranslated region of the TBSV genome. Thus, efficient translation of TBSV mRNA in vivo requires a 5'-3' RNA-RNA interaction that effectively circularizes the message. Similar types of interactions are also predicted to occur in TBSV subgenomic mRNAs between their 5' untranslated regions and the 3' CITE, and both genomic and subgenomic 5'-3' interactions are well conserved in all members of the genus Tombusvirus. In addition, a survey of other genera in Tombusviridae revealed the potential for similar 5'-3' RNA-RNA-based interactions in their viral mRNAs, suggesting that this mechanism extends throughout this large virus family.