Kohara Y, Tohdoh N, Jiang X W, Okazaki T
Nucleic Acids Res. 1985 Oct 11;13(19):6847-66. doi: 10.1093/nar/13.19.6847.
RNA-linked DNA molecules were obtained from E. coli dnaCts cells synchronously initiating a new round of chromosome replication. The deoxynucleotides at the transition from primer RNA to DNA were 32P-labeled, and their positions were located on the nucleotide sequence of 1.4 kb genomic region (position -906 to +493) including the oriC and its leftside flanking region. In the r-strand (the counterclockwise strand), many strong transition sites were mapped in the left half portion of the oriC and a few weak sites in the left outside region. In the 1-strand (the clockwise strand), no transition sites were found inside the oriC but many weak sites were found in the left outside region. The results support the initiation mechanism in which the first leading strand synthesis starts with the r-strand counterclockwise from the oriC that is followed by the 1-strand synthesis on the displaced template strand on the left of oriC. Primer RNA molecules attached to the strong r-strand transition sites were only a few residues in length. Properties of the transition sites were discussed.
从同步启动新一轮染色体复制的大肠杆菌 dnaCts 细胞中获得了 RNA 连接的 DNA 分子。从引物 RNA 转变为 DNA 时的脱氧核苷酸用 32P 进行了标记，并且它们的位置定位在包括 oriC 及其左侧侧翼区域的 1.4 kb 基因组区域（位置 -906 至 +493）的核苷酸序列上。在 r 链（逆时针链）中，许多强转变位点定位在 oriC 的左半部分，在左侧外部区域有一些弱位点。在 1 链（顺时针链）中，在 oriC 内部未发现转变位点，但在左侧外部区域发现了许多弱位点。这些结果支持了起始机制，即第一条前导链的合成从 oriC 逆时针方向的 r 链开始，随后在 oriC 左侧被置换的模板链上进行 1 链合成。附着在强 r 链转变位点上的引物 RNA 分子长度只有几个残基。讨论了转变位点的性质。
