Aiba H, Adhya S, de Crombrugghe B
J Biol Chem. 1981 Nov 25;256(22):11905-10.
We have used an S1 mapping assay to demonstrate that the mRNA transcripts of the Escherichia coli galactose operon found in intact E. coli cells with a defect in adenylate cyclase or the cyclic AMP receptor protein contain at their 5' end about five nucleotides more than the gal mRNA molecules made in wild type cells. The same difference between gal RNA synthesized in vitro in the absence of cyclic AMP or cyclic AMP receptor protein and gal RNA made in the presence of these factors is detected by this assay. Our results strongly suggest that the same two overlapping promoters, which we previously identified by in vitro transcription of gal DNA fragments, also control the expression of the galactose operon in intact cells. The intracellular levels of cyclic AMP determine which promoter is utilized.
我们使用了S1图谱分析来证明，在腺苷酸环化酶或环磷酸腺苷受体蛋白有缺陷的完整大肠杆菌细胞中发现的大肠杆菌半乳糖操纵子的mRNA转录本，其5'端比野生型细胞中产生的半乳糖mRNA分子多约五个核苷酸。通过该分析检测到，在无环磷酸腺苷或环磷酸腺苷受体蛋白的情况下体外合成的半乳糖RNA与在这些因子存在下产生的半乳糖RNA之间存在相同差异。我们的结果强烈表明，我们之前通过半乳糖DNA片段的体外转录鉴定出的相同两个重叠启动子，也控制完整细胞中半乳糖操纵子的表达。细胞内环磷酸腺苷的水平决定了使用哪个启动子。
