Larsen J E, Gerdes K, Light J, Molin S
Gene. 1984 Apr;28(1):45-54. doi: 10.1016/0378-1119(84)90086-6.
By insertion of a DNA fragment, containing the phage lambda pR promoter and the pM-promoted cI857 allele of the lambda repressor gene, in plasmid R1 upstream of the replication control genes, cloning vectors have been constructed which are present in one copy per chromosome at temperatures below 37 degrees C, and which display uncontrolled replication at 42 degrees C. Derivatives have been made which carry the R1 par region, stabilizing the plasmid at low temperature when grown in the absence of selection pressure. Cells harbouring these plasmids stop growing after 1-2 h incubation at 42 degrees C, and at this time 50% of the total DNA in the cells is plasmid DNA corresponding to more than 1000 plasmid molecules per cell. Concomitant with plasmid amplification at the high temperature, synthesis of plasmid-coded gene products is amplified, and these vectors can therefore be utilized for obtaining greatly enhanced yields of gene products that may be detrimental to the host cell when present in large amounts.
通过将包含噬菌体λ pR启动子和λ阻遏基因的pM启动的cI857等位基因的DNA片段插入质粒R1复制控制基因上游，构建了克隆载体。这些载体在低于37摄氏度的温度下以每条染色体一个拷贝的形式存在，而在42摄氏度时表现出不受控制的复制。已经制备了携带R1 par区域的衍生物，当在没有选择压力的情况下生长时，可在低温下稳定质粒。携带这些质粒的细胞在42摄氏度孵育1 - 2小时后停止生长，此时细胞中总DNA的50%是质粒DNA，相当于每个细胞有超过1000个质粒分子。随着高温下质粒的扩增，质粒编码基因产物的合成也被放大，因此这些载体可用于获得大量增加的基因产物产量，而这些基因产物大量存在时可能对宿主细胞有害。
