Johnston J C, Rochon D M
Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.
Virology. 1995 Dec 1;214(1):100-9. doi: 10.1006/viro.1995.9950.
Sequences comprising the core promoter for the cucumber necrosis virus (CNV) 0.9-kb subgenomic RNA have been determined using deletion analysis and site-directed mutagenesis. The deletion studies indicate that the promoter lies within a region located 20 nucleotides upstream and 6 nucleotides downstream and including the subgenomic start site. Sequences further upstream or downstream of the core promoter do not appear to strongly affect promoter activity or viral RNA accumulation. Results of site-directed mutagenesis studies indicate that nucleotides immediately surrounding the subgenomic start site regulate promoter activity. Comparison of sequences within the CNV promoter region with the corresponding region of other tombusviruses shows that the tombusvirus promoter shares a region of near complete identity in 14 of the 26 core promoter nucleotides. Little similarity exists between the CNV 0.9-kb subgenomic RNA promoter and the region surrounding the transcription initiation site for the CNV 2.1-kb subgenomic RNA. Likewise, limited similarity occurs with the 5' region of CNV genomic RNA. Sequences similar to the ICR2-like motifs found in the promoters of several alphavirus-like (supergroup III) plant and animal viruses are not apparent. This study represents the first analysis of a subgenomic promoter from a member of supergroup II of positive-strand RNA viruses.
通过缺失分析和定点诱变，已确定了黄瓜坏死病毒（CNV）0.9 kb亚基因组RNA的核心启动子序列。缺失研究表明，该启动子位于亚基因组起始位点上游20个核苷酸和下游6个核苷酸的区域内，且包括该起始位点。核心启动子上下游的序列似乎对启动子活性或病毒RNA积累没有强烈影响。定点诱变研究结果表明，紧邻亚基因组起始位点的核苷酸调节启动子活性。将CNV启动子区域内的序列与其他番茄丛矮病毒的相应区域进行比较，结果显示在26个核心启动子核苷酸中，番茄丛矮病毒启动子有14个核苷酸具有几乎完全相同的区域。CNV 0.9 kb亚基因组RNA启动子与CNV 2.1 kb亚基因组RNA转录起始位点周围区域之间几乎没有相似性。同样，与CNV基因组RNA的5'区域的相似性也有限。在几种α病毒样（超组III）植物和动物病毒启动子中发现的类似ICR2基序的序列并不明显。这项研究首次对正链RNA病毒超组II成员的亚基因组启动子进行了分析。
