Kasteel D, Wellink J, Verver J, van Lent J, Goldbach R, van Kammen A
Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands.
J Gen Virol. 1993 Aug;74 ( Pt 8):1721-4. doi: 10.1099/0022-1317-74-8-1721.
On the surface of cowpea protoplasts inoculated with cowpea mosaic virus (CPMV), tubular structures containing virus particles have been found. Such tubular structures are thought to be involved in cell-to-cell movement of CPMV in cowpea plants. To study the involvement of the 58K/48K and capsid proteins of CPMV in the formation of the tubular structures, mutations were introduced into M cDNA clones from which infectious transcripts could be derived. No tubules were found on protoplasts inoculated with a mutant that fails to produce the 48K protein nor with a mutant that has a deletion in the 48K coding region, suggesting that the 48K protein is essential for this process. However, a possible role of the 58K protein in tubule formation could not be excluded. A mutant that fails to produce the capsid proteins did produce tubules and therefore the capsid proteins are not involved in the formation of the tubular structures. Electron microscopic analysis revealed that the tubules produced by this mutant are, apart from the absence of virus particles, morphologically identical to the tubules formed by the wild-type virus.
在用豇豆花叶病毒（CPMV）接种的豇豆原生质体表面，已发现含有病毒粒子的管状结构。这种管状结构被认为参与了CPMV在豇豆植株中的细胞间移动。为了研究CPMV的58K/48K蛋白和衣壳蛋白在管状结构形成中的作用，对可产生感染性转录本的M cDNA克隆引入了突变。在用无法产生48K蛋白的突变体接种的原生质体上，以及在用48K编码区有缺失的突变体接种的原生质体上，均未发现小管，这表明48K蛋白对该过程至关重要。然而，不能排除58K蛋白在小管形成中的可能作用。一个无法产生衣壳蛋白的突变体确实产生了小管，因此衣壳蛋白不参与管状结构的形成。电子显微镜分析表明, 除了没有病毒粒子外，该突变体产生的小管在形态上与野生型病毒形成的小管相同。
