Cross-induction of glc and ace operons of Escherichia coli attributable to pathway intersection -: Characterization of the glc promoter
Cross-induction of glc and ace operons of Escherichia coli attributable to pathway intersection -: Characterization of the glc promoter
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DOI：
10.1074/jbc.274.3.1745
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发表时间：
1999-01-15
影响因子：
4.8
通讯作者：
Baldomà, L
中科院分区：
文献类型：
--
作者：
Pellicer, MT;Fernandez, C;Baldomà, L
大肠杆菌中glc和ace操纵子指定的代谢途径产生乙醛酸作为共同中间体，其由两种苹果酸合酶同工酶作用：一种由glcB编码，另一种由aceB编码。由于乙醇酸对ace操纵子的交叉诱导和乙酸对glc操纵子的交叉诱导，两个基因的突变都没有表现出表型。在这项研究中，glc操纵子，包括结构基因glcDEFGB的调节，在分子水平上进行了分析。该操纵子通过在乙醇酸盐上生长而激活，被转录为单一信息，并且处于由趋异基因编码的GlcC的正控制下。glc操纵子的表达强烈依赖于整合宿主因子（IHF），并受到全局呼吸调节因子ArcA-P的抑制。体外凝胶转移实验证明启动子DNA与IHF和ArcA-P直接结合。突变分析表明，乙酸酯对glc操纵子的交叉诱导是由GlcC蛋白介导的，该蛋白识别该化合物作为替代效应子。IHF和ArcA-P对Glc和Ace系统的类似调控模式确保了它们的有效交叉诱导。
The metabolic pathways specified by the glc and ace operons in Escherichia coli yield glyoxylate as a common intermediate, which is acted on by two malate synthase isoenzymes: one encoded by glcB and the other by aceB. Null mutations in either gene exhibit no phenotype, because of cross-induction of the ace operon by glycolate and the glc operon by acetate. In this study, the regulation of the glc operon, comprising the structural genes glcDEFGB, was analyzed at the molecular level. This operon, activated by growth on glycolate, is transcribed as a single message and is under the positive control of GlcC encoded by a divergent gene. Expression of the glc operon is strongly dependent on the integration host factor (IHF) and is repressed by the global respiratory regulator ArcA-P, In vitro gel-shift experiments demonstrated direct binding of the promoter DNA to IHF and ArcA-P. Mutant analysis indicated that cross-induction of the glc operon by acetate is mediated by the GlcC protein that recognizes the compound as an alternative effector. The similar pattern of regulation of the Glc and Ace systems by IHF and ArcA-P ensures their effective cross-induction.