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首页> 外文期刊>Journal of bacteriology >Molecular cloning of Escherichia coli K-12 hexuronate system genes: exu region.
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Molecular cloning of Escherichia coli K-12 hexuronate system genes: exu region.

机译：大肠杆菌K-12己糖酸酯系统基因的分子克隆：exu区。

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摘要

Lambda transducing bacteriophages carrying the exu region (min 66) of Escherichia coli K-12 (lambda pexu) were previously isolated. A restriction map of these phages is presented. Starting from the lambda pexu phage deoxyribonucleic acid, various endonuclease-generated exu fragments were subcloned into multicopy plasmid vectors, using in vitro recombination techniques. The precise location of the exu genes, relative to the endonuclease sites, was determined. Plasmids carrying uxaC and uxaA genes overproduced the corresponding enzymes 30- to 40-fold. When these plasmids were expressed in an in vitro protein-synthesizing system, two polypeptides of 50,500 and 53,000 molecular weights appeared and were identified as the uxaC and uxaA gene products. A 2.6-kilobase-pair deoxyribonucleic acid fragment was shown to code for a functional exuR repressor which controls the expression of the exu region. Plasmids containing this fragment overproduced the regulatory protein. It was possible to localize the operator region, uxaCo, which overlapped a PstI endonuclease site, and to confirm the transcriptional direction of the uxaC-uxaA operon from uxaC to uxaA.
机译：预先分离出携带大肠杆菌K-12的exu区（min 66）的λ转导噬菌体。给出了这些噬菌体的限制性图谱。使用体外重组技术，从λ噬菌体脱氧核糖核酸开始，将各种内切核酸酶生成的exu片段亚克隆到多拷贝质粒载体中。确定了exu基因相对于核酸内切酶位点的精确位置。带有uxaC和uxaA基因的质粒过量产生了30至40倍的相应酶。当这些质粒在体外蛋白质合成系统中表达时，出现了两种分子量分别为50,500和53,000的多肽，并被确定为uxaC和uxaA基因产物。显示了一个2.6碱基对的脱氧核糖核酸片段编码功能性exuR阻遏物，该阻遏物控制exu区域的表达。含有该片段的质粒过量产生调节蛋白。可以定位与PstI核酸内切酶位点重叠的操纵子区域uxaCo，并确定uxaC-uxaA操纵子从uxaC到uxaA的转录方向。

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