Gottlieb P, Strassman J, Qiao X Y, Frucht A, Mindich L
Department of Microbiology, Public Health Research Institute, New York, New York 10016.
J Bacteriol. 1990 Oct;172(10):5774-82. doi: 10.1128/jb.172.10.5774-5782.1990.
The genome of the lipid-containing bacteriophage phi 6 contains three segments of double-stranded RNA (dsRNA). We prepared cDNA copies of the viral genome and cloned this material in plasmids that replicate in Escherichia coli and Pseudomonas phaseolicola, the natural host of phi 6. These plasmids direct the formation of viral proteins and the assembly of structures similar to viral procapsids containing proteins P1, P2, P4, and P7. We found that these particles are capable of taking up viral single-stranded RNA and synthesizing the minus strands to produce dsRNA structures. Once the dsRNA is formed, it is then used as a template for the production of viral plus strands in a reaction that resembles normal transcription. The particles were also capable of directly transcribing exogenous dsRNA. The replicase reactions were specific for phi 6 RNA, were specific for procapsids, and resulted in substantial incorporation of product dsRNA into particles. These results offer strong support to a model in which genomic packaging is done by preformed procapsids.
含脂质噬菌体phi 6的基因组包含三段双链RNA(dsRNA)。我们制备了病毒基因组的cDNA拷贝,并将该材料克隆到在大肠杆菌和phi 6的天然宿主菜豆假单胞菌中复制的质粒中。这些质粒指导病毒蛋白的形成以及类似于含有蛋白P1、P2、P4和P7的病毒原衣壳结构的组装。我们发现这些颗粒能够摄取病毒单链RNA并合成负链以产生dsRNA结构。一旦dsRNA形成,它随后被用作模板,在类似于正常转录的反应中产生病毒正链。这些颗粒也能够直接转录外源dsRNA。复制酶反应对phi 6 RNA具有特异性,对原衣壳具有特异性,并导致大量产物dsRNA掺入颗粒中。这些结果为基因组包装由预先形成的原衣壳完成的模型提供了有力支持。