Molecular analysis of the essential and nonessential genetic elements in the genome of peanut chlorotic streak caulimovirus.
Molecular analysis of the essential and nonessential genetic elements in the genome of peanut chlorotic streak caulimovirus.
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DOI：
10.1006/viro.1995.1005
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发表时间：
1995-02
期刊：
影响因子：
3.7
通讯作者：
Arcady Mushegian;J. A. Wolff;R. Richins;R. J. Shepherd
中科院分区：
文献类型：
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作者：
Arcady Mushegian;J. A. Wolff;R. Richins;R. J. Shepherd
花椰菜花叶病毒的DNA基因组包含一组必需基因：I（运动基因）、IV（主要衣壳蛋白基因）、V（逆转录酶基因）和VI（编码其他病毒基因表达的转录后激活因子的基因）。在花生褪绿条斑花椰菜花叶病毒（PCISV）中，位于基因I和IV之间的三个ORF A、B和C。它们与其他花椰菜病毒的ORF不同。PCISV的ORF VII与大豆褪绿斑驳花椰菜花叶病毒（SoCMV）的ORF VII同源，但与其他花椰菜花叶病毒的非保守ORF VII不相似。与tRNA（Met）的一部分互补的序列位于ORF A的编码序列内，该序列被认为是引发花椰菜花叶病毒中负链DNA合成所必需的。为了探索ORF VII、A、B和C的功能意义，将各种突变工程化到PCISV的感染性DNA克隆中。ORF VII和B是必需的，而ORF A和C是必需的。ORF C可能是其他花椰菜花叶病毒中基因III的功能等价物。负链合成的有效引发所需的ORF A内的序列可能延伸超过12-bp的tRNA结合位点。ORF VII的完全缺失与严重的症状相关，特别是与顶端分生组织的坏死相关。这些观察的意义，了解植物副轮状病毒的复制和发病机制，并为改进基于花椰菜花叶病毒的表达载体进行了讨论。
The DNA genome of caulimoviruses contains a set of essential genes: I (movement gene), IV (major capsid protein gene), V (reverse transcriptase gene), and VI (gene coding for a post-transcriptional activator of the expression of other virus genes). In peanut chlorotic streak caulimovirus (PCISV), three ORFs, A, B, and C, are located between genes I and IV. They are dissimilar to other caulimovirus ORFs. ORF VII of PCISV is a homolog of ORF VII of soybean chlorotic mottle caulimovirus (SoCMV), but is not similar to the nonconserved ORF VII in other caulimoviruses. The sequence complementary to a portion of tRNA(Met), thought to be essential for the priming of minus-strand DNA synthesis in caulimoviruses, is located within the coding sequence of ORF A. To explore the functional significance of ORFs VII, A, B, and C, various mutations were engineered into an infectious DNA clone of PCISV. ORFs VII and B are shown to be dispensable, while ORFs A and C are essential. ORF C is a possible functional equivalent of gene III in other caulimoviruses. Sequences within ORF A that are required for efficient priming of minus-strand synthesis are likely to extend beyond the 12-bp tRNA-binding site. Complete deletion of ORF VII was correlated with severe symptoms, notably with the necrosis of apical meristems. Significance of these observations for the understanding of replication and pathogenesis of plant pararetroviruses and for the improvement of caulimovirus-based expression vectors is discussed.