The Escherichia coli chromosome is a circular double helix. DNA polymerase, therefore, cannot use it directly as a template for polymerization until it has first been unwound. The DnaA protein opens the chromosome at a unique and specific site (oriC), which allows the polymerase to begin DNA replication. François Jacob and Sydney Brenner predicted the existence of the initiator protein, DnaA, back in the early 1960s. In order to demonstrate the existence of the hypothetical initiator, identification and isolation of dnaA mutants were undertaken. In the following, I recount, in a historical setting, the original research done on the identification and isolation of dnaA mutants.

在大肠杆菌染色体是一个圆形的双螺旋。因此，DNA聚合酶必须先解开后才能直接用作聚合反应的模板。DnaA蛋白在唯一且特定的位点（oriC）打开染色体，从而允许聚合酶开始DNA复制。弗朗索瓦·雅各布（FrançoisJacob）和悉尼·布伦纳（Sydney Brenner）早在1960年代初就预测了起始蛋白DnaA的存在。为了证明假设的引发剂的存在，进行了dnaA突变体的鉴定和分离。在下文中，我回顾一下历史背景下有关dnaA突变体鉴定和分离的原始研究。