Transcription from efficient promoters can interfere with plasmid replication and diminish expression of plasmid specified genes.
Transcription from efficient promoters can interfere with plasmid replication and diminish expression of plasmid specified genes.
复制标题
高效启动子的转录可以干扰质粒复制并减少质粒特定基因的表达。
作者：
D. Stueber;H. Bujard
含有ColE1复制子的质粒的拷贝数受到质粒内转录活性变化的影响，如果这些变化导致转录通读进入复制区，朝向启动子引发DNA复制。这种通读例如，从pBR 322的泰特区域中分离的DNA不仅导致已知负面影响拷贝数的肽的过量产生，而且似乎负面干扰质粒本身的复制。有效转录终止子的适当放置防止了这种干扰，并允许强启动子的稳定整合。由于这种终止效应，根据特定的生长条件，观察到质粒拷贝数差异高达9倍。当然，较高的拷贝数反映为质粒特异性基因产物的较高产量，表明上述效应与基因表达研究相关。
The copy number of plasmids containing the ColE1 replicon is affected by changes in the transcriptional activity within the plasmid if these changes lead to transcriptional readthrough into the replication region towards the promoter priming DNA replication. Such readthrough e.g., from the tet region in pBR322 not only causes overproduction of a peptide known to affect the copy number negatively but also appears to interfere negatively with the replication of the plasmid itself. The proper placement of efficient transcriptional terminators prevents such interference and permits the stable integration of strong promoters. Due to this termination effect, up to 9‐fold differences in plasmid copy number were observed, depending upon the particular growth conditions. The higher copy number is of course reflected by higher yields of plasmid‐specified gene products indicating the relevance of the above effects for studies of gene expression.