Whitehouse A, Cooper M, Hall K T, Meredith D M
Molecular Medicine Unit, University of Leeds, St. James's University Hospital, United Kingdom.
J Virol. 1998 Mar;72(3):1967-73. doi: 10.1128/JVI.72.3.1967-1973.1998.
We have previously demonstrated that open reading frame (ORF) 50 and ORF 57 encode transcriptional regulating genes in herpesvirus saimiri. ORF 50, a homolog of Epstein-Barr virus R protein, is a sequence-specific transactivator, whereas ORF 57 acts posttranscriptionally. In this report, we demonstrate that the ORF 57 gene is regulated by the ORF 50a gene product. We show that the ORF 57 gene is expressed at basal levels early in the virus replication cycle and that thereafter it is transactivated by the ORF 50a gene product, due to an increase in RNA levels. As it has been shown that the ORF 57 gene product downregulates ORF 50a due to the presence of its intron, these combined observations identify a feedback mechanism modulating gene expression in herpesvirus saimiri, whereby ORF 50a transcription is downregulated by the ORF 57 gene product, a gene which it specifically transactivates. Furthermore, we propose that the intron-containing ORF 57 gene downregulates itself by the same mechanism as that for ORF 50a, as both genes are downregulated at similar times during the replication cycle.
我们之前已经证明，开放阅读框（ORF）50和ORF 57在猴疱疹病毒中编码转录调节基因。ORF 50是爱泼斯坦-巴尔病毒R蛋白的同源物，是一种序列特异性反式激活因子，而ORF 57在转录后发挥作用。在本报告中，我们证明ORF 57基因受ORF 50a基因产物的调控。我们发现，ORF 57基因在病毒复制周期早期以基础水平表达，此后由于RNA水平的增加而被ORF 50a基因产物反式激活。正如已经表明的，由于其内含子的存在，ORF 57基因产物下调ORF 50a，这些综合观察结果确定了一种调节猴疱疹病毒基因表达的反馈机制，即ORF 57基因产物下调ORF 50a的转录，而ORF 57基因产物是它特异性反式激活的基因。此外，我们提出，含有内含子的ORF 57基因通过与ORF 50a相同的机制下调自身，因为这两个基因在复制周期的相似时间被下调。
