Aramaki H, Fujita M, Sagara Y, Amemura A, Horiuchi T
Department of Microbiology, Daiichi College of Pharmaceutical Sciences, Fukuoka, Japan.
FEMS Microbiol Lett. 1994 Oct 15;123(1-2):49-54. doi: 10.1111/j.1574-6968.1994.tb07200.x.
The cytochrome P450cam hydroxylase operon (camDCAB) of Pseudomonas putida is negatively regulated by a repressor, CamR, which also represses its own gene. The expression in P. putida of both camR and camDCAB is derepressed in the presence of D-camphor. We examined the expression in Escherichia coli of camR and camDCAB by monitoring the enzyme activity of the camD gene product. In the presence or absence of D-camphor in the cell culture, the expression in E. coli of camD was significant and constitutive, suggesting no expression of camR. This lack of expression was confirmed by monitoring the beta-galactosidase activity of camR-lacZ translational fusions. However, S1 nuclease mapping revealed that synthesis of camR mRNA in E. coli was significant and constitutive, as observed in the case of camDCAB mRNA. Thus, it is likely that the expression of camR in E. coli is limited at the translational level.
恶臭假单胞菌的细胞色素P450cam羟化酶操纵子（camDCAB）受到阻遏物CamR的负调控，CamR也会抑制其自身基因。在D-樟脑存在的情况下，恶臭假单胞菌中camR和camDCAB的表达都会去阻遏。我们通过监测camD基因产物的酶活性来检测camR和camDCAB在大肠杆菌中的表达。在细胞培养物中存在或不存在D-樟脑的情况下，camD在大肠杆菌中的表达都是显著且组成型的，这表明camR没有表达。通过监测camR-lacZ翻译融合体的β-半乳糖苷酶活性，证实了这种缺乏表达的情况。然而，S1核酸酶图谱分析表明，与camDCAB mRNA的情况一样，大肠杆菌中camR mRNA的合成是显著且组成型的。因此，camR在大肠杆菌中的表达很可能在翻译水平上受到限制。
