Bujarski J J, Nagy P D
Plant Molecular Biology Center, Northern Illinois University, DeKalb.
Arch Virol Suppl. 1994;9:231-8. doi: 10.1007/978-3-7091-9326-6_23.
The genome of brome mosaic virus (BMV) consists of three positive strand RNA segments that share a high degree of sequence homology in the 3' noncoding region. The phenomenon of both homologous and nonhomologous intersegment RNA-RNA recombinant has been demonstrated within the 3' noncoding region of BMV RNAs. It has been postulated that nonhomologous crossovers occur at local heteroduplexes formed between the recombining BMV RNA substrates of the same polarity and that the formation of double-stranded regions facilitates strand switching by the replicase. To test the hypothesis of hybridization-mediated recombination in BMV, RNA-3 constructs carrying short antisense RNA1-derived sequences have been used to induce nonhomologous recombination events between RNA-1 and RNA-3 at or near the site of hybridization. We find that both the incidence of recombination and the location of recombinant junctions depends on the structure and the stability of heteroduplexes. Furthermore, our preliminary results demonstrate that mutations in the helicase-like domain of BMV protein 1a affect the location of recombinant junctions. This provides experimental evidence that BMV replicase protein 1a participates in recombination.
雀麦花叶病毒（BMV）的基因组由三个正链RNA片段组成，这些片段在3'非编码区具有高度的序列同源性。在BMV RNA的3'非编码区内已证实存在同源和非同源片段间RNA-RNA重组现象。据推测，非同源交叉发生在相同极性的重组BMV RNA底物之间形成的局部异源双链体处，并且双链区域的形成促进了复制酶的链交换。为了验证BMV中杂交介导的重组假说，携带短反义RNA1衍生序列的RNA-3构建体已被用于在杂交位点或其附近诱导RNA-1和RNA-3之间的非同源重组事件。我们发现重组发生率和重组连接点的位置均取决于异源双链体的结构和稳定性。此外，我们的初步结果表明，BMV蛋白1a的解旋酶样结构域中的突变会影响重组连接点的位置。这提供了实验证据，证明BMV复制酶蛋白1a参与重组。
