Mackem S, Roizman B
J Virol. 1982 Sep;43(3):1015-23. doi: 10.1128/JVI.43.3.1015-1023.1982.
In cells infected with herpes simplex virus 1, the expression of viral genes is coordinately regulated and sequentially ordered; the alpha genes are expressed first and are followed by beta and gamma genes in a cascade fashion. Earlier, this laboratory reported (Post et al., Cell 24:555-565, 1981) that a chimeric gene, constructed by the replacement of 50 base pairs of DNA coding for 5' nontranslated leader and sequences upstream of the site of transcription initiation of thymidine kinase (a beta gene) by corresponding sequences of alpha gene no. 4, was regulated as an alpha gene. Of particular interest was the observation that in cells converted to TK(+) phenotype, the chimeric gene was positively regulated by superinfecting virus. In this paper, we report two series of experiments. First, we determined that transcription of alpha gene no. 27 is initiated at or near a five-nucleotide sequence flanked by an eight-nucleotide perfect inverted repeat situated from 256 to 277 bases to the right of the left terminus of the BamHI B fragment. In the second series of experiments, we constructed a chimeric gene which consisted of the thymidine kinase sequences described above but was fused to a DNA fragment expected to contain the promoter-regulatory region of alpha gene 27 and stretching from approximately -270 to the +55 nucleotide. The chimeric gene in converted cells was amplified upon superinfection with TK(-) virus only when the promoter-regulatory region was in the correct transcriptional orientation relative to the leader and structural sequences of the thymidine kinase gene. The requirements for amplification of the expression of this chimeric thymidine kinase gene were exactly the same as those previously reported for the alpha gene no. 4-thymidine kinase chimera and different from those of the standard (beta) thymidine kinase. We conclude that the positive regulation of expression of alpha gene no. 4 deduced in previous studies may be a general property of alpha genes and that the promoter-regulatory region of alpha gene no. 27 is within a sequence contained between -270 and +55 nucleotides relative to the transcription initiation site.
在感染单纯疱疹病毒1的细胞中，病毒基因的表达受到协调调控且具有顺序性；α基因首先表达，随后β和γ基因以级联方式相继表达。此前，本实验室报道（波斯特等人，《细胞》24:555 - 565，1981年），通过用α4基因的相应序列替换编码胸苷激酶（一个β基因）5'非翻译前导序列和转录起始位点上游50个碱基对的DNA构建的嵌合基因，其调控方式与α基因相同。特别有趣的是观察到，在转化为胸苷激酶阳性（TK(+)）表型的细胞中，该嵌合基因受到超感染病毒的正向调控。在本文中，我们报告了两个系列的实验。首先，我们确定α27基因的转录起始于或靠近一个五核苷酸序列，该序列两侧是一个八核苷酸的完美反向重复序列，位于BamHI B片段左端末端右侧256至277个碱基处。在第二个系列的实验中，我们构建了一个嵌合基因，它由上述胸苷激酶序列组成，但与一个预期包含α27基因启动子调控区域且从大约 -270到 +55核苷酸延伸的DNA片段融合。只有当启动子调控区域相对于胸苷激酶基因的前导序列和结构序列处于正确的转录方向时，在转化细胞中超感染TK(-)病毒后，该嵌合基因才会被扩增。这个嵌合胸苷激酶基因表达扩增的要求与先前报道的α4基因 - 胸苷激酶嵌合体完全相同，与标准（β）胸苷激酶的要求不同。我们得出结论，先前研究中推断的α4基因表达的正向调控可能是α基因的普遍特性，并且α27基因的启动子调控区域位于相对于转录起始位点 -270至 +55核苷酸之间的序列内。
