Department of Biology, York University, Toronto, Ontario, Canada.
Virology. 2011 Sep 15;418(1):1-11. doi: 10.1016/j.virol.2011.07.005. Epub 2011 Jul 30.
Tobacco necrosis virus-D (TNV-D), a positive-strand RNA Necrovirus in the family Tombusviridae, transcribes two subgenomic (sg) mRNAs during infections. We have investigated the strategy used by TNV-D in this process and uncovered evidence that it employs a premature termination (PT) mechanism for the transcription of its sg mRNAs. Structural and mutational analysis of the TNV-D genome identified local RNA structures upstream from transcriptional initiation sites that functioned in the plus-strand as attenuation structures and mediated the production of sg mRNA-sized minus-strands. Other evidence in support of a PT mechanism included the ability to uncouple minus-strand sg RNA production from plus-strand sg mRNA synthesis and the sequence similarities observed between the sg mRNA promoter and that for the viral genome. Accordingly, our results indicate that the necrovirus TNV-D, like several other genera in the family Tombusviridae, uses a PT mechanism for transcription of its sg mRNAs.
烟草坏死病毒-D（TNV-D）是一种正链 RNA 坏死病毒，属于 Tombusviridae 科。在感染过程中，它转录两种亚基因组（sg）mRNA。我们研究了 TNV-D 在这个过程中使用的策略，并发现了它利用过早终止（PT）机制来转录 sg mRNA 的证据。对 TNV-D 基因组的结构和突变分析鉴定了转录起始位点上游的局部 RNA 结构，这些结构在正链中作为衰减结构发挥作用，并介导 sg mRNA 大小的负链的产生。支持 PT 机制的其他证据包括能够将负链 sg RNA 的产生与正链 sg mRNA 合成解耦，以及在 sg mRNA 启动子和病毒基因组之间观察到的序列相似性。因此，我们的结果表明，像 Tombusviridae 科的其他几个属一样，坏死病毒 TNV-D 利用 PT 机制来转录其 sg mRNA。
