Blanc M, Briat J F, Laulhere J P
Biochim Biophys Acta. 1981 Oct 27;655(3):374-82. doi: 10.1016/0005-2787(81)90048-4.
The in vitro transcription of chloroplast DNA (ctDNA) is studied using a DNA-protein complex isolated from spinach plastids. The RNA products are compared to the in vivo synthesized ctRNA by competition for hybridization. At least 80% of the in vitro RNA sequences are present in vivo. Modifications of ionic strength or introduction of heparin in the reaction medium has an important effect on transcriptional activity of the complex. Furthermore, the length of the RNA chains increases ionic strength and amount of heparin. The RNA products are analysed by Southern hybridizations to EcoRI cTDNA fragments. Changes in the ionic strength or in the amount of heparin modify heterogeneously the transcription of the various DNA regions. The quantitative distribution of transcripts among the ctDNA fragments is used as evidence for the selectivity of the transcription. The activity of the DNA-protein complex is much more resistant to high ionic strength than an heterologous transcription system using Escherichia coli RNA polymerase and ctDNA. This latter system transcribes less ctDNA fragments.
利用从菠菜质体中分离出的DNA - 蛋白质复合物研究叶绿体DNA（ctDNA）的体外转录。通过杂交竞争将RNA产物与体内合成的ctRNA进行比较。至少80%的体外RNA序列存在于体内。反应介质中离子强度的改变或肝素的引入对复合物的转录活性有重要影响。此外，RNA链的长度会随着离子强度和肝素量的增加而增加。通过Southern杂交分析RNA产物与EcoRI cTDNA片段。离子强度或肝素量的变化会不均匀地改变各个DNA区域的转录。转录本在ctDNA片段中的定量分布被用作转录选择性的证据。与使用大肠杆菌RNA聚合酶和ctDNA的异源转录系统相比，DNA - 蛋白质复合物的活性对高离子强度的耐受性要强得多。后一种系统转录的ctDNA片段较少。
