Hendrickson E A, Fritze C E, Folk W R, DePamphilis M L
Department of Biological Chemistry, Harvard Medical School, Boston, MA 02115.
EMBO J. 1987 Jul;6(7):2011-8. doi: 10.1002/j.1460-2075.1987.tb02465.x.
The nucleotide locations of RNA-p-DNA covalent linkages in polyoma virus (PyV) replicating DNA were mapped in the region containing the genetically required origin of DNA replication (ori). These linkages mark the initiation sites for RNA-primed DNA synthesis. A clear transition was identified between the presence of these linkages (discontinuous DNA synthesis) and their absence (continuous DNA synthesis) on each strand of ori. This demonstrated that PyV DNA replication, like simian virus 40 (SV40), is semi-discontinuous, and thus revealed the location of the origin of bidirectional DNA replication (OBR). The transition site on the template encoding PyV late mRNA occurred at the junction of ori-core and T-antigen binding site A. This was essentially the same site as previously observed in SV40 (Hay and DePamphilis, 1982). However, in contrast to SV40, the transition site on the template encoding PyV early mRNA was displaced towards the late gene side of ori. This resulted in a 16 nucleotide gap within ori in which no RNA-p-DNA linkages were observed on either strand. A model for the initiation of PyV DNA replication is presented.
在多瘤病毒（PyV）复制的DNA中，RNA-p-DNA共价连接的核苷酸位置被定位在包含基因所需的DNA复制起点（ori）的区域。这些连接标记了RNA引发的DNA合成的起始位点。在ori的每条链上，这些连接的存在（不连续DNA合成）和不存在（连续DNA合成）之间确定了一个明显的转变。这表明PyV DNA复制与猴病毒40（SV40）一样，是半不连续的，从而揭示了双向DNA复制起点（OBR）的位置。编码PyV晚期mRNA的模板上的转变位点发生在ori核心与T抗原结合位点A的交界处。这基本上与之前在SV40中观察到的位点相同（Hay和DePamphilis，1982）。然而，与SV40不同的是，编码PyV早期mRNA的模板上的转变位点向ori的晚期基因侧移动。这导致ori内出现一个16个核苷酸的间隙，在该间隙的两条链上均未观察到RNA-p-DNA连接。本文提出了一个PyV DNA复制起始的模型。
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