A Viral Noncoding RNA Generated by cis-Element-Mediated Protection against 5′→3′ RNA Decay Represses both Cap-Independent and Cap-Dependent Translation
A Viral Noncoding RNA Generated by cis-Element-Mediated Protection against 5′→3′ RNA Decay Represses both Cap-Independent and Cap-Dependent Translation
复制标题
DOI：
10.1128/jvi.01027-08
复制
发表时间：
2008-10-01
影响因子：
5.4
通讯作者：
Okuno, Tetsuro
中科院分区：
文献类型：
--
作者：
Iwakawa, Hiro-oki;Mizumoto, Hiroyuki;Okuno, Tetsuro
正链RNA病毒使用不同的机制来调节病毒和宿主基因的表达，以确保它们在宿主中的有效增殖或持久存在。我们发现一个小的病毒非编码RNA（0.4 kb），命名为SR 1f，积累在红三叶草坏死花叶病毒（RCNMV）感染的植物和原生质体，并包装成病毒粒子。RCNMV的基因组由两条正链RNA组成，RNA 1和RNA 2。SR 1f由RNA 1的3'非翻译区（UTR）产生，其含有对帽非依赖性翻译和负链RNA合成都必需的RNA元件。在RNA 1的3'非翻译区（3' UTR）有一段58个核苷酸的序列（Seq 1f 58）是产生SR 1f所必需的。SR 1f既不是亚基因组RNA，也不是缺陷RNA复制子，而是Seq 1f 58介导的抗5 '-> 3'衰变的稳定降解产物。SR 1f在体外和体内均有效地抑制帽非依赖性和帽依赖性翻译。SR 1f反式抑制RCNMV基因组RNA的负链RNA合成，通过抑制复制酶蛋白的产生，但不通过复制酶蛋白的竞争在体外。RCNMV似乎使用细胞酶来产生SR 1f，其可能在RCNMV感染中起调节作用。我们的研究结果还表明，Seq 1f 58是一个RNA元件，保护3 '-侧RNA序列免受5'-> 3'衰变在植物细胞中，如报道的聚（G）道和稳定的茎环结构在酿酒酵母。
Positive-strand RNA viruses use diverse mechanisms to regulate viral and host gene expression for ensuring their efficient proliferation or persistence in the host. We found that a small viral noncoding RNA (0.4 kb), named SR1f, accumulated in Red clover necrotic mosaic virus (RCNMV)-infected plants and protoplasts and was packaged into virions. The genome of RCNMV consists of two positive-strand RNAs, RNA1 and RNA2. SR1f was generated from the 3' untranslated region (UTR) of RNA1, which contains RNA elements essential for both cap-independent translation and negative-strand RNA synthesis. A 58-nucleotide sequence in the 3' UTR of RNA1 (Seq1f58) was necessary and sufficient for the generation of SR1f. SR1f was neither a subgenomic RNA nor a defective RNA replicon but a stable degradation product generated by Seq1f58-mediated protection against 5'-> 3' decay. SR1f efficiently suppressed both cap-independent and cap-dependent translation both in vitro and in vivo. SR1f trans inhibited negative-strand RNA synthesis of RCNMV genomic RNAs via repression of replicase protein production but not via competition of replicase proteins in vitro. RCNMV seems to use cellular enzymes to generate SR1f that might play a regulatory role in RCNMV infection. Our results also suggest that Seq1f58 is an RNA element that protects the 3'-side RNA sequences against 5'-> 3' decay in plant cells as reported for the poly(G) tract and stable stem-loop structure in Saccharomyces cerevisiae.