Valentin-Hansen P, Svenningsen B A, Munch-Petersen A, Hammer-Jespersen K
Mol Gen Genet. 1978 Feb 16;159(2):191-202. doi: 10.1007/BF00270893.
The synthesis of the four enzymes of the deo operon in Escherichia coli is known from in vivo experiments to be subject to a double negative control, exerted by the products of the cytR and deoR genes. A DNA-directed in vitro protein synthesizing system makes the deo enzymes (exemplified by thymidine phosphorylase) in agreement with in vivo results. Enzyme synthesis is stimulated by cyclic AMP and repressed by the cytR and deoR gene products. Repression by the cytR repressor is reversed by cytidine or adenosine in the presence of cyclic AMP, while repression by the deoR repressor is reversed by deoxyribose-5-phosphate. Assays for the presence of the cytR and deoR repressors were established by use of S-30 extracts prepared from the regulatory mutants. Dissociation constants for repressor-operator binding as well as for repressor-inducer interactions have been estimated from the results.
已知在体内实验中，大肠杆菌中deo操纵子的四种酶的合成受到cytR和deoR基因产物的双重负调控。DNA指导的体外蛋白质合成系统产生的deo酶（以胸苷磷酸化酶为例）与体内实验结果一致。酶的合成受环腺苷酸刺激，并受cytR和deoR基因产物的抑制。在环腺苷酸存在的情况下，胞苷或腺苷可逆转cytR阻遏物的抑制作用，而脱氧核糖-5-磷酸可逆转deoR阻遏物的抑制作用。通过使用从调节突变体中制备的S-30提取物建立了检测cytR和deoR阻遏物存在的方法。根据结果估算了阻遏物与操纵基因结合以及阻遏物与诱导物相互作用的解离常数。
