Genetic evidence for an essential role for potyvirus CI protein in cell-to-cell movement
Genetic evidence for an essential role for potyvirus CI protein in cell-to-cell movement
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DOI：
10.1046/j.1365-313x.1998.00120.x
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发表时间：
1998-05-01
期刊：
影响因子：
7.2
通讯作者：
Schaad, MC
中科院分区：
文献类型：
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作者：
Carrington, JC;Jensen, PE;Schaad, MC
马铃薯Y病毒属圆柱形包涵体（CI）蛋白是基因组复制所需的RNA解旋酶，采用丙氨酸扫描诱变技术对CI蛋白进行了遗传分析。将31个突变引入到表达β-葡萄糖醛酸酶或绿色荧光蛋白报告基因的经修饰的烟草蚀纹病毒（TEV）基因组的CI蛋白编码区中。12个突变体在原生质体接种试验中是复制缺陷型的。在这19个具有复制能力的突变体中，有几个突变体在烟草植株中具有细胞间运动或长距离运动缺陷。两个突变体，AS 1和AS 8，仅限于单细胞接种叶片，尽管基因组扩增水平相当于亲本病毒。其他突变体，如AS 9和AS 14，能够缓慢地在细胞间移动，但在长距离移动中变得虚弱。这些数据为CI蛋白在马铃薯Y病毒属细胞间运动中的直接作用以及CI蛋白在基因组复制和运动中的不同作用提供了遗传学证据。结合高分辨率的超微结构分析和以前的遗传数据，这些结果支持了一个模型，其中CI蛋白直接与胞间连丝和衣壳蛋白的核糖核蛋白复合物相互作用，以促进马铃薯Y病毒属细胞到细胞的运动。
The potyvirus cylindrical inclusion (CI) protein, an RNA helicase required for genome replication, was analyzed genetically using alanine-scanning mutagenesis. Thirty-one mutations were introduced into the CI protein coding region of modified tobacco etch virus (TEV) genomes expressing either beta-glucuronidase or green fluorescent protein reporters. Twelve of the mutants were replication-defective in protoplast inoculation assays. Among the 19 replication-competent mutants, several possessed cell-to-cell or long-distance movement defects in tobacco plants. Two mutants, AS1 and AS8, were restricted to single cells in inoculated leaves despite genome amplification levels that were equivalent to that of parental virus. Other mutants, such as AS9 and AS14, were able to move cell to cell slowly but were debilitated in long-distance movement. These data provide genetic evidence for a direct role of CI protein in potyvirus intercellular movement, and for distinct roles of the CI protein in genome replication and movement. In combination with high-resolution ultrastructural analyzes and previous genetic data, these results support a model in which CI protein interacts directly with plasmodesmata and capsid protein-containing ribonucleoprotein complexes to facilitate potyvirus cell-to-cell movement.