Jat P, Roberts J W, Cowie A, Kamen R
Nucleic Acids Res. 1982 Feb 11;10(3):871-87. doi: 10.1093/nar/10.3.871.
Polyoma virus DNA was transcribed in the HeLa whole cell extract in vitro system (1). Early region transcripts with the same 5'-ends as in vivo mRNAs, located 31 +/- 2bp from 'TATA'-boxes, were synthesized by RNA polymerase II. Sequences sufficient for efficient expression of the early promoter were present in a substitution mutant lacking viral DNA from a position 55bp before the principal cap sites. Late region transcripts were synthesised inefficiently. Only one (at nt5129 +/- 2) of the many late mRNA cap sites functioned as an in vitro initiation point. This was the one 5'-end located 31 +/- 2bp from a sequence resembling the 'TATA' consensus. The proportion of late to early region RNA polymerase II transcripts decreased dramatically at suboptimal template concentrations. An hypothesis to explain the regulation of late gene expression in vivo based on these results is proposed. A linear templates were transcribed only by RNA polymerase II, transcripts with the same sense as late mRNAs and 5'-ends at nt5076 +/- 2 were produced from superhelical template by an alpha amanitin resistant enzyme.
多瘤病毒DNA在体外的HeLa全细胞提取物系统中进行转录（1）。早期区域转录本与体内mRNA具有相同的5'端，位于距“TATA”框31±2bp处，由RNA聚合酶II合成。在一个缺失主要帽位点前55bp处病毒DNA的替代突变体中，存在足以有效表达早期启动子的序列。晚期区域转录本的合成效率较低。许多晚期mRNA帽位点中只有一个（位于nt5129±2处）作为体外起始点发挥作用。这是唯一一个5'端位于距类似“TATA”共有序列31±2bp处的位点。在次优模板浓度下，晚期与早期区域RNA聚合酶II转录本的比例急剧下降。基于这些结果，提出了一个解释体内晚期基因表达调控的假说。线性模板仅由RNA聚合酶II转录，超螺旋模板通过一种α-鹅膏蕈碱抗性酶产生与晚期mRNA具有相同意义且5'端位于nt5076±2处的转录本。
