Mindich L
Department of Microbiology, The Public Health Research Institute New York, New York 10016, USA.
Microbiol Mol Biol Rev. 1999 Mar;63(1):149-60. doi: 10.1128/MMBR.63.1.149-160.1999.
Bacteriophage phi6 has a genome of three segments of double-stranded RNA. Each virus particle contains one each of the three segments. Packaging is effected by the acquisition, in a serially dependent manner, of the plus strands of the genomic segments into empty procapsids. The empty procapsids are compressed in shape and expand during packaging. The packaging program involves discrete steps that are determined by the amount of RNA inside the procapsid. The steps involve the exposure and concealment of binding sites on the outer surface of the procapsid for the plus strands of the three genomic segments. The plus strand of segment S can be packaged alone, while packaging of the plus strand of segment M depends upon prior packaging of S. Packaging of the plus strand of L depends upon the prior packaging of M. Minus-strand synthesis begins when the particle has a full complement of plus strands. Plus-strand synthesis commences upon the completion of minus-strand synthesis. All of the reactions of packaging, minus-strand synthesis, and plus-strand synthesis can be accomplished in vitro with isolated procapsids. Live-virus constructions that are in accord with the model have been prepared. Mutant virus with changes in the packaging program have been isolated and analyzed.
噬菌体phi6具有由三段双链RNA组成的基因组。每个病毒粒子包含这三段中的每一段各一个。包装过程通过以序列依赖的方式将基因组片段的正链获取到空的原衣壳中来实现。空的原衣壳形状压缩并在包装过程中膨胀。包装程序涉及由原衣壳内RNA量决定的离散步骤。这些步骤包括原衣壳外表面上针对三个基因组片段正链的结合位点的暴露和隐藏。片段S的正链可以单独包装，而片段M正链的包装取决于S的预先包装。L正链的包装取决于M的预先包装。当粒子具有完整的正链互补时，负链合成开始。正链合成在负链合成完成后开始。包装、负链合成和正链合成的所有反应都可以在体外使用分离的原衣壳完成。已经制备了符合该模型的活病毒构建体。已经分离并分析了包装程序发生变化的突变病毒。
