Identification of Novel 5′ and 3′ Translation Enhancers in Umbravirus-Like Coat Protein-Deficient RNA Replicons
Identification of Novel 5′ and 3′ Translation Enhancers in Umbravirus-Like Coat Protein-Deficient RNA Replicons
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DOI：
10.1128/jvi.01736-21
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发表时间：
2022-03
影响因子：
5.4
通讯作者：
Jingyuan Liu;A. Simon
中科院分区：
文献类型：
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作者：
Jingyuan Liu;A. Simon
类似本影的相关 RNA (ulaRNA) 是最近发现的一种亚病毒 RNA，它使用其编码的 RNA 依赖性 RNA 聚合酶进行复制，但不编码任何外壳蛋白、运动蛋白或沉默抑制子，但可以在没有任何可识别辅助病毒的植物中找到。我们报告了使用 2 类 ulaRNA 柑橘黄脉相关病毒 (CYVaV) 对其翻译的首次分析。摘要 缺少 5' 帽的植物正链 RNA 病毒基因组的翻译通常需要使用位于 3' 非翻译区 (UTR) 或其附近的帽独立翻译增强子 (CITE)。 3'CITE 根据二级结构和与不同翻译起始因子或核糖体亚基相互作用的能力进行分组，这些翻译起始因子或核糖体亚基在 3' 末端组装一个复合物，该复合物几乎总是通过 3'CITE 和 5' 发夹序列之间的长距离接吻环相互作用转移到 5' 末端。我们在这里报告了在与umbraviruses相关的外壳蛋白缺陷的RNA复制子中鉴定出一个新的3'CITE。类本影相关 RNA (ulaRNA)，例如柑橘黄脉相关病毒 (CYVaV)，是一种新型亚病毒 RNA，不编码运动蛋白、外壳蛋白或沉默抑制子，但可以使用其编码的 RNA 依赖性 RNA 聚合酶独立复制。 CYVaV 3' UTR 中包含多个内部环的延伸发夹结构在最密切相关的 ulaRNA 中高度保守，并且在结构上类似于 I 形结构 (ISS) 3'CITE。然而，与 ISS 不同，CYVaV 结构与 eIF4G 结合，并且 CYVaV ISS 样结构与 5' 端或附近的序列之间没有可辨别的长距离相互作用。我们还报道，当与 CYVaV 3'CITE 或 umbravirus 豌豆花叶病毒 (PEMV2) 的 3'CITE 相关时，CYVaV 和相关 ulaRNA 的~30-核苷酸 (nt) 5' 末端发夹可以增强报告构建体的翻译，甚至独立于 3'CITE。这些发现引入了一种新型 3'CITE，并提供了有关 ulaRNA 翻译的第一个信息。重要性 Umbra 样相关 RNA (ulaRNA) 是最近发现的一种亚病毒 RNA，它使用其编码的 RNA 依赖性 RNA 聚合酶进行复制，但不编码任何外壳蛋白、运动蛋白或沉默抑制子，但可以在没有任何可识别辅助病毒的植物中找到。我们报告了使用 2 类 ulaRNA 柑橘黄脉相关病毒 (CYVaV) 对其翻译的首次分析。 CYVaV 使用新型 eIF4G 结合 I 形结构作为其 3' 帽独立翻译增强子 (3'CITE)，该结构不通过 3'CITE 典型的长距离 RNA:RNA 相互作用与 5' 端连接。 ulaRNA 5'末端发夹还可以增强与同源 3'CITE 或相关 ulaRNA 相关的翻译，并在较小程度上与umbraviruses的 3'CITE 相关，甚至独立于 3'CITE。这些发现引入了一种新型 3'CITE，并提供了有关 ulaRNA 翻译的第一个信息。
Umbra-like associated RNAs (ulaRNAs) are a recently discovered type of subviral RNA that use their encoded RNA-dependent RNA polymerase for replication but do not encode any coat proteins, movement proteins, or silencing suppressors yet can be found in plants in the absence of any discernible helper virus. We report the first analysis of their translation using class 2 ulaRNA citrus yellow vein-associated virus (CYVaV). ABSTRACT Translation of plant plus-strand RNA viral genomes that lack a 5′ cap frequently requires the use of cap-independent translation enhancers (CITEs) located in or near the 3′ untranslated region (UTR). 3′CITEs are grouped based on secondary structure and ability to interact with different translation initiation factors or ribosomal subunits, which assemble a complex at the 3′ end that is nearly always transferred to the 5′ end via a long-distance kissing-loop interaction between sequences in the 3′CITE and 5′ hairpins. We report here the identification of a novel 3′CITE in coat protein-deficient RNA replicons that are related to umbraviruses. Umbra-like associated RNAs (ulaRNAs), such as citrus yellow vein-associated virus (CYVaV), are a new type of subviral RNA that do not encode movement proteins, coat proteins, or silencing suppressors but can independently replicate using their encoded RNA-dependent RNA polymerase. An extended hairpin structure containing multiple internal loops in the 3′ UTR of CYVaV is strongly conserved in the most closely related ulaRNAs and structurally resembles an I-shaped structure (ISS) 3′CITE. However, unlike ISS, the CYVaV structure binds to eIF4G and no long-distance interaction is discernible between the CYVaV ISS-like structure and sequences at or near the 5′ end. We also report that the ∼30-nucleotide (nt) 5′ terminal hairpin of CYVaV and related ulaRNAs can enhance translation of reporter constructs when associated with either the CYVaV 3′CITE or the 3′CITEs of umbravirus pea enation mosaic virus (PEMV2) and even independent of a 3′CITE. These findings introduce a new type of 3′CITE and provide the first information on translation of ulaRNAs. IMPORTANCE Umbra-like associated RNAs (ulaRNAs) are a recently discovered type of subviral RNA that use their encoded RNA-dependent RNA polymerase for replication but do not encode any coat proteins, movement proteins, or silencing suppressors yet can be found in plants in the absence of any discernible helper virus. We report the first analysis of their translation using class 2 ulaRNA citrus yellow vein-associated virus (CYVaV). CYVaV uses a novel eIF4G-binding I-shaped structure as its 3′ cap-independent translation enhancer (3′CITE), which does not connect with the 5′ end by a long-distance RNA:RNA interaction that is typical of 3′CITEs. ulaRNA 5′ terminal hairpins can also enhance translation in association with cognate 3′CITEs or those of related ulaRNAs and, to a lesser extent, with 3′CITEs of umbraviruses, or even independent of a 3′CITE. These findings introduce a new type of 3′CITE and provide the first information on translation of ulaRNAs.