Vos J C, Stunnenberg H G
European Molecular Biology Laboratory, Heidelberg, FRG.
EMBO J. 1988 Nov;7(11):3487-92. doi: 10.1002/j.1460-2075.1988.tb03224.x.
A novel class of vaccinia virus genes, called intermediate, is expressed immediately post-replication and prior to the onset of late gene transcription. Intermediate transcription is dependent on trans-acting factors which are present in an active state in virus-infected cells prior to the onset of DNA replication. Plasmid-borne intermediate genes transfected into vaccinia-virus infected cells are expressed prior to DNA replication, whereas the copies within the viral genome are repressed. DNA replication is essential for activation of viral intermediate transcription and de novo protein synthesis is not required post-replication. In contrast, activation of late transcription depends on DNA replication and continued de novo protein synthesis. Therefore, a subset of intermediate proteins is likely to be trans-activators of late gene transcription. Cell-free extracts differentially transcribe early, intermediate and late genes in a way similar to the temporal expression observed in vivo. A cascade model is discussed for the regulation of gene expression during the viral life-cycle.
一类名为中间基因的新型痘苗病毒基因在复制后立即表达，且在晚期基因转录开始之前表达。中间转录依赖于反式作用因子，这些因子在DNA复制开始之前以活性状态存在于病毒感染的细胞中。转染到痘苗病毒感染细胞中的质粒携带的中间基因在DNA复制之前表达，而病毒基因组中的拷贝则受到抑制。DNA复制对于病毒中间转录的激活至关重要，复制后不需要从头合成蛋白质。相比之下，晚期转录的激活依赖于DNA复制和持续的从头合成蛋白质。因此，一部分中间蛋白可能是晚期基因转录的反式激活因子。无细胞提取物以类似于体内观察到的时间表达的方式差异转录早期、中间和晚期基因。本文讨论了病毒生命周期中基因表达调控的级联模型。
