Expression of glnA in Escherichia coli is regulated at tandem promoters.
Expression of glnA in Escherichia coli is regulated at tandem promoters.
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大肠杆菌中 glnA 的表达受到串联启动子的调节。
DOI：
10.1073/pnas.82.7.1979
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发表时间：
1985
影响因子：
11.1
通讯作者：
Magasanik,B
中科院分区：
文献类型：
--
作者：
Reitzer,LJ;Magasanik,B
我们已经确定大肠杆菌复杂的glnALG操纵子的glnA基因是从串联启动子转录而来的。上游启动子glnAp1的表达需要分解代谢激活蛋白，受GLNG产物氮调节因子I(NRI)的抑制，并产生一个含有187个核苷酸的未翻译前导的转录本。下游启动子glnAp2的表达不仅需要GLNF产物，还需要NRI；完整的表达还需要在氮限制的环境中生长。下游转录本有73个核苷酸的未翻译前导序列。我们还提供了证据表明，glnL产物的功能是调节NRI在能够激活glnAp2的形式和响应细胞内氨浓度变化的非活性形式之间的相互转换。GlnALG操纵子的两个次要启动子glnAp1和glnLp的功能是在碳限制生长过程中维持谷氨酰胺合成酶GlnA和氮控制基因激活因子GLNG NRI的产物。
We have determined that the glnA gene of the complex glnALG operon of Escherichia coli is transcribed from tandem promoters. Expression from the upstream promoter, glnAp1, requires the catabolite activating protein, is repressed by nitrogen regulator I (NRI), the product of glnG, and produces a transcript with an untranslated leader of 187 nucleotides. Expression from the downstream promoter, glnAp2, requires NRI as well as the glnF product; full expression also requires growth in a nitrogen-limited environment. The downstream transcript has an untranslated leader of 73 nucleotides. We also provide evidence that the function of the glnL product is to mediate the interconversion of NRI between a form capable of activating glnAp2 and an inactive form in response to changes in the intracellular concentration of ammonia. The function of the two minor promoters of the glnALG operon, glnAp1 and glnLp, is to maintain the products of glnA, glutamine synthetase, an essential enzyme, and of glnG, NRI, an activator of nitrogen-controlled genes, during carbon-limited growth.