Enger-Valk B E, van Rotterdam J, Pouwels P H
Nucleic Acids Res. 1981 Apr 24;9(8):1973-89. doi: 10.1093/nar/9.8.1973.
We have constructed new plasmids that can be used to clone transcription terminator containing DNA fragments between the first gene of the tryptophan (trp) operon and the tetracycline resistance (tet) gene. Both genes are under control of the trp promotor. Therefore the presence of a transcription termination signal on cloned fragments can be monitored by a decrease in expression of the tet gene. The plasmids contain cloning sites at different distances from the translation start signal. Consequently a cloned DNA fragment can be translated in the three possible reading frames, offering the opportunity to distinguish terminators from translation polarity (pseudo-terminators). The usefulness of the plasmids was shown by the cloning of the trp terminator and of a pseudo-terminator located in the trpB gene.
我们构建了新的质粒，可用于在色氨酸（trp）操纵子的第一个基因与四环素抗性（tet）基因之间克隆含转录终止子的DNA片段。这两个基因均受trp启动子的控制。因此，可通过tet基因表达的降低来监测克隆片段上转录终止信号的存在。这些质粒在距翻译起始信号不同距离处含有克隆位点。因此，克隆的DNA片段可以在三种可能的阅读框中进行翻译，从而有机会将终止子与翻译极性（假终止子）区分开来。通过克隆trp终止子和位于trpB基因中的假终止子，证明了这些质粒的实用性。
