Chang C, Hirsch R C, Ganem D
Howard Hughes Medical Institute, University of California Medical Center, San Francisco 94143-0502.
Virology. 1995 Mar 10;207(2):549-54. doi: 10.1006/viro.1995.1115.
The pregenomic RNA of hepadnaviruses serves as both the mRNA for the core and polymerase proteins and the RNA template for reverse transcription. We have identified a region in the duck hepatitis B virus pregenomic RNA transcription unit that is critical for the accumulation of this transcript. This 85-nt region, termed alpha, is located within the preC region; deletion of alpha results in drastically reduced steady-state levels of pregenomic RNA. This effect is not due to reduction in transcription initiation or to enhancement of premature polyadenylation at the 5' copy of the viral poly(A) signal. However, this phenotype is suppressed by deletion of a second, larger region (beta) located ca. 1 kb downstream. The activity of the alpha element is tissue- and species-nonspecific; however, it displays absolute orientation-dependence and its activity is influenced by its position within the transcript. Models for its action are discussed.
嗜肝DNA病毒的前基因组RNA既是核心蛋白和聚合酶蛋白的信使核糖核酸，也是逆转录的RNA模板。我们在鸭乙型肝炎病毒前基因组RNA转录单元中鉴定出一个区域，该区域对于此转录本的积累至关重要。这个85个核苷酸的区域，称为α，位于前C区域内；删除α会导致前基因组RNA的稳态水平大幅降低。这种效应不是由于转录起始的减少或病毒多聚腺苷酸信号5'拷贝处过早多聚腺苷酸化的增强。然而，通过删除位于约1 kb下游的第二个更大区域（β），这种表型受到抑制。α元件的活性不具有组织和物种特异性；然而，它表现出绝对的方向依赖性，并且其活性受其在转录本中的位置影响。文中讨论了其作用模型。
