Pierson L S, Kahn M L
Mol Gen Genet. 1984;195(1-2):44-51. doi: 10.1007/BF00332722.
The integration and attachment regions of bacteriophage P4 have been cloned into a multicopy plasmid. This plasmid can integrate into the E. coli chromosome at the same location as the parent phage. Integration increases the stability of the plasmid and allows it to be retained even under conditions in which a non-integrated plasmid would be lost. None of the genes needed for P4 lytic growth is required for integration. The P4 integration and attachment regions have been cloned on separate plasmids. A plasmid that carries the attachment site can integrate into the chromosome only if another plasmid that carries the P4 integration functions is present. A plasmid that carries only this trans-acting integration function cannot integrate. Using deletion mutants of the plasmid, the maximum size of the region needed for integration has been determined to be 1.6 kb, of which no more than 1.2 kb codes for the integrase protein. A nonsense mutant defective in integration has been isolated by using a rapid screening procedure that identifies unstable plasmids.
噬菌体P4的整合和附着区域已被克隆到一个多拷贝质粒中。该质粒能在与亲代噬菌体相同的位置整合到大肠杆菌染色体中。整合增加了质粒的稳定性，使其即使在非整合质粒会丢失的条件下也能保留下来。P4裂解生长所需的基因均不是整合所必需的。P4整合和附着区域已被克隆到不同的质粒上。携带附着位点的质粒只有在存在携带P4整合功能的另一个质粒时才能整合到染色体中。仅携带这种反式作用整合功能的质粒不能整合。利用该质粒的缺失突变体，已确定整合所需区域的最大大小为1.6 kb，其中编码整合酶蛋白的不超过1.2 kb。通过使用一种能识别不稳定质粒的快速筛选程序，分离出了一个整合缺陷的无义突变体。
