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首页> 外文期刊>Journal of bacteriology >Regulation of galactose operon at the gal operator-promoter region in Escherichia coli K-12.
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Regulation of galactose operon at the gal operator-promoter region in Escherichia coli K-12.

机译：大肠杆菌K-12中gal操纵子启动子区域的半乳糖操纵子的调控。

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The capR (lon) product controls expression of the gal operon independently of the galR repressor. Previously, mutations of the gal operon have been isolated that are semiconstitutive and alter response to the capR and/or capT product. Such mutants imply the existence of a distinct site in the operon that responds to capR (capT) control. This mutation could be either in a site near the operator-distal end of the galE gene, which signals rho factor termination of transcription in vitro or in a site in the operator-promoter region. Bacteriophage U3 was used to isolate galE mutations in HC2142 (a mutant exhibiting reduced response to capR control). P1 transduction was used to cross these mutants with a set of galE gene deletion. Analysis of the resulting Gal+ recombinants indicates that the regulatory site is in the operator-promoter region. Hence, it is unlikely that capR functions in control as an anti-rho factor at the operator-distal end of the galE gene, but more likely as previously suggested, at a second operator distinct from one responding to galR repressor control. Upon induction with D-fucose, a promoter mutant (UV211) isolated previously expressed 20 to 30% of the galactose enzymes that the wild type exhibited in the presence of the inducer D-fucose. The effects of various mutations in cya, capR, and galR on galactokinase synthesis in this mutant were determined. Galactokinase was derepressed by capR as well as galR, but the presence or absence of the cya gene product was unimportant.
机译：capR（lon）产物独立于galR阻遏物控制gal操纵子的表达。以前，已分离出半操纵基因的gal操纵子突变，并改变了对capR和/或capT产物的反应。此类突变体暗示操纵子中存在一个对capR（capT）控制有反应的独特位点。该突变可能在galE基因的操纵基因远端附近的一个位点中，该信号表明体外转录的rho因子终止或在操纵基因启动子区域中的一个位点。噬菌体U3用于分离HC2142中的galE突变（对capR对照显示出降低的响应的突变体）。 P1转导用于使这些突变体与一组galE基因缺失杂交。对所得Gal +重组体的分析表明，调控位点在操纵子-启动子区域。因此，在galE基因的操纵基因远端，capR不可能作为抗rho因子在控制中起作用，但更有可能如先前所建议的那样，在不同于对galR阻遏物控制作出反应的第二个操纵基因上发挥作用。用D-岩藻糖诱导后，先前分离的启动子突变体（UV211）表达了在诱导剂D-岩藻糖存在下野生型表现出的20至30％的半乳糖酶。确定了cya，capR和galR中各种突变对该突变体中半乳糖激酶合成的影响。半乳糖激酶被capR和galR抑制，但cya基因产物的存在与否并不重要。

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