Infection of capilloviruses requires subgenomic RNAs whose transcription is controlled by promoter-like sequences conserved among flexiviruses
Infection of capilloviruses requires subgenomic RNAs whose transcription is controlled by promoter-like sequences conserved among flexiviruses
复制标题
DOI：
10.1016/j.virusres.2012.02.019
复制
发表时间：
2012-07-01
期刊：
影响因子：
5
通讯作者：
Namba, Shigetou
中科院分区：
文献类型：
--
作者：
Komatsu, Ken;Hirata, Hisae;Namba, Shigetou
苹果茎沟病毒(ASGV)的第一个开放阅读框(ORF)编码一个明显嵌合的多聚蛋白，其中含有复制酶(Rep)和外壳蛋白(CP)的保守区。然而，我们先前的研究发现，具有不同的和不连续的Rep和CP编码区的ASGV突变体成功地侵染植物，表明通过亚基因组RNA(SgRNA)表达的CP足以维持病毒的生存。在这里，我们确定了CP sgRNA的转录起始点，并揭示了从sgRNA翻译的CP在ASGV感染中是必不可少的。我们定位了ASGV CP和运动蛋白(MP)sgRNAs的转录起始点，发现在这两个sgRNA转录起始点的上游都有一个保守的六核苷酸基序UUAGGU。推测的CP起始密码子和CP sgRNA转录起始点上游的UUAGGU序列的突变分析表明，它们对ASGV的积累具有重要意义。我们的结果还表明，马铃薯病毒T(PVT)是一个与ASGV关系密切的未指定物种，它产生两个sgRNAs，推测用于CP和MP的表达，并且与ASGV中发现的相同的六核苷酸基序位于这两个sgRNAs转录起始点的上游。该基序构成了sgRNA启动子的核心元件，在阿尔法病毒科和贝塔病毒科病毒中广泛保守，表明这两个家族病毒的基因表达策略在进化过程中一直是保守的。(C)2012爱思唯尔B.V.保留所有权利。
The first open-reading frame (ORF) of apple stem grooving virus (ASGV), of the genus Capillovirus, encodes an apparently chimeric polyprotein containing conserved regions for replicase (Rep) and coat protein (CP). However, our previous study revealed that ASGV mutants with distinct and discontinuous Rep- and CP-coding regions successfully infect plants, indicating that CP expressed via a subgenomic RNA (sgRNA) is sufficient for viability of the virus. Here we identified a transcription start site of the CP sgRNA and revealed that CP translated from the sgRNA is essential for ASGV infection. We mapped the transcription start sites of both the CP and the movement protein (MP) sgRNAs of ASGV and found a hexanucleotide motif, UUAGGU, conserved upstream from both sgRNA transcription start sites. Mutational analysis of the putative CP initiation codon and of the UUAGGU sequence upstream from the transcription start site of CP sgRNA demonstrated their importance for ASGV accumulation. Our results also demonstrated that potato virus T (PVT), an unassigned species closely related to ASGV, produces two sgRNAs putatively deployed for the CP and MP expression and that the same hexanucleotide motif as found in ASGV is located upstream from the transcription start sites of both sgRNAs. This motif, which constituted putative core elements of the sgRNA promoter, is broadly conserved among viruses in the families Alphaflexiviridae and Betaflexiviridae, suggesting that the gene expression strategy of the viruses in both families has been conserved throughout evolution. (C) 2012 Elsevier B.V. All rights reserved.