Brenner M, Tomizawa J
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892.
Nucleic Acids Res. 1989 Jun 12;17(11):4309-26. doi: 10.1093/nar/17.11.4309.
The ColE1 Rom protein contributes to copy number control by affecting the rate of formation of a complex between RNA II, the precursor of the primer for DNA replication, and RNA I, a small RNA complementary to the 5' end of RNA II. Interaction of RNA I with RNA II can affect plasmid copy number by preventing primer formation. Although the RNA I and RNA II transcripts have been well characterized, the rom mRNA has not previously been detected. We have now identified the rom mRNA, and determined its start site both in vitro and in vivo. We also have found that the rom mRNA terminates at any of several sites, and that its synthesis is not autoregulated by the Rom protein. By using an internal standard RNA to estimate the efficiency of detection of the rom mRNA, its level was determined to be about 1 molecule per cell.
ColE1 Rom蛋白通过影响RNA II（DNA复制引物的前体）与RNA I（与RNA II 5'端互补的小RNA）之间复合物的形成速率来控制拷贝数。RNA I与RNA II的相互作用可通过阻止引物形成来影响质粒拷贝数。尽管RNA I和RNA II转录本已得到充分表征，但此前尚未检测到rom mRNA。我们现已鉴定出rom mRNA，并在体外和体内确定了其起始位点。我们还发现rom mRNA在几个位点中的任何一个处终止，并且其合成不受Rom蛋白的自动调节。通过使用内标RNA来估计rom mRNA的检测效率，确定其水平约为每个细胞1个分子。
