The role of EF-Tu in the expression of tufA and tufB genes.
The role of EF-Tu in the expression of tufA and tufB genes.
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EF-Tu 在 tufA 和 tufB 基因表达中的作用。
DOI：
10.1111/j.1432-1033.1983.tb07166.x
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Leendert Bosch
中科院分区：
文献类型：
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作者：
P. H. V. D. Meide;E. Vijgenboom;A. Talens;Leendert Bosch
我们研究了EF-Tu的两个编码基因tufA和tufB在大肠杆菌中的表达调控。为此目的，我们通过免疫测定法在大肠杆菌突变体中测定了不同生长条件下EF-TuA和EF-TuB的细胞内浓度。为此目的构建的大肠杆菌。数据显示，在野生型细胞中，tufA和tufB的表达是协调调节的。这种协调不限于稳态生长条件，而是在细胞的整个生命周期中维持，直到稳定期。然而，这两种基因表达的比例在具有不同遗传组成的细胞中可能不同。从细胞中完全消除EF-TuB（通过将噬菌体Mu DNA插入tufB）或提高细胞内EF-TuB浓度（通过用携带tufB的质粒转化）对tufA的表达都没有任何影响。然而，tufA的一个特定的单位点突变，使EF-TuA对抗生素kirromycin具有抗性，干扰了tufA和tufB的协调表达，专门增强了tufB的表达。这些结果已被解释为假设在野生型细胞中的EF-Tu蛋白本身参与调节的tufB的表达和EF-Tu的突变体物种已经失去了这种能力的部分或完全。与该假设一致的是，用偶联的转录/翻译系统在体外进行的实验，所述偶联的转录/翻译系统用来自携带整个tRNA-tufB转录单位的质粒的DNA作为模板编程。它们表明，向该系统中加入浓度为内源量的2-5%的EF-Tu导致EF-Tu合成的强烈抑制。我们假设EF-Tu作为一个自体阻遏物，抑制转录后tufB的表达。
We have studied the regulation of the expression of tufA and tufB, the two genes encoding EF-Tu in Escherichia coli. To this aim we have determined the intracellular concentrations of EF-TuA and EF-TuB under varying growth conditions by an immunological assay in mutants of E. coli constructed for this purpose. The data show that in wild-type cells the expression of tufA and tufB is regulated coordinately. This coordination is not restricted to steady-state growth conditions but is maintained throughout the life cycle of the cells up till the stationary phase. The ratio in which the two genes are expressed, however, may vary among cells with different genetic constitutions. Neither complete elimination of EF-TuB from the cell (by insertion of bacteriophage Mu DNA into tufB) nor elevation of the intracellular EF-TuB concentration (by transformation with plasmids harbouring tufB) has any effect on the expression of tufA. A specific single-site mutation of tufA, however, rendering EF-TuA resistant to the antibiotic kirromycin, disturbs the coordinate expression of tufA and tufB, enhancing tufB expression exclusively. These results have been interpreted by assuming that in wild-type cells the EF-Tu protein itself is involved in the regulation of the expression of tufB and that the mutant species of EF-Tu has lost this capacity either partially or completely. In agreement with this hypothesis are experiments performed in vitro with a coupled transcription/translation system programmed with DNA from a plasmid harbouring the entire tRNA-tufB transcriptional unit as a template. They show that addition to this system of EF-Tu in concentrations 2-5% of the endogenous amount results in strong inhibition of EF-Tu synthesis. We hypothesize that EF-Tu acts as an autogenous repressor, inhibiting tufB expression post-transcriptionally.