Shimada K, Fukumaki Y, Takagi Y
Mol Gen Genet. 1976 Aug 19;147(2):203-8. doi: 10.1007/BF00267572.
Studies were made on two guanine-requiring strains of Escherichia coli isolated independently as a result of insertion of prophage gamma into one of the structural genes of the guanine operon. These mutants do not exhibit any detectable guaB function but express the guaA function constitutively at a low level, presumably due to transcription from the pI promoter on the prophage. Various types of plaque-forming gua-transducing phages were generated from these lysogens. The approximate location and the mode of substitution of the gua genes in the phage genome were determined. These results clearly indicate that the gene guaB is located closer to the operator-promoter region of the gua operon than is guaA, and the gene order is "operator"-guaB-guaA.
对两株独立分离得到的需要鸟嘌呤的大肠杆菌菌株进行了研究，这是由于原噬菌体γ插入到鸟嘌呤操纵子的一个结构基因中所致。这些突变体不表现出任何可检测到的guaB功能，但以低水平组成型表达guaA功能，推测是由于原噬菌体上pI启动子的转录。从这些溶原菌中产生了各种类型的形成噬菌斑的gua转导噬菌体。确定了噬菌体基因组中gua基因的大致位置和取代模式。这些结果清楚地表明，guaB基因比guaA基因更靠近鸟嘌呤操纵子的操纵子-启动子区域，基因顺序为“操纵子”-guaB-guaA。
