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首页> 外文期刊>Journal of bacteriology >The Alcohol Dehydrogenase Gene adhA in Corynebacterium glutamicum Is Subject to Carbon Catabolite Repression
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The Alcohol Dehydrogenase Gene adhA in Corynebacterium glutamicum Is Subject to Carbon Catabolite Repression

机译：谷氨酸棒杆菌中的酒精脱氢酶基因adhA受到碳分解代谢物的抑制

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Corynebacterium glutamicum has recently been shown to grow on ethanol as a carbon and energy source and to possess high alcohol dehydrogenase (ADH) activity when growing on this substrate and low ADH activity when growing on ethanol plus glucose or glucose alone. Here we identify the C. glutamicum ADH gene (adhA), analyze its transcriptional organization, and investigate the relevance of the transcriptional regulators of acetate metabolism RamA and RamB for adhA expression. Sequence analysis of adhA predicts a polypeptide of 345 amino acids showing up to 57% identity with zinc-dependent ADH enzymes of group I. Inactivation of the chromosomal adhA gene led to the inability to grow on ethanol and to the absence of ADH activity, indicating that only a single ethanol-oxidizing ADH enzyme is present in C. glutamicum. Transcriptional analysis revealed that the C. glutamicum adhA gene is monocistronic and that its expression is repressed in the presence of glucose and of acetate in the growth medium, i.e., that adhA expression is subject to catabolite repression. Further analyses revealed that RamA and RamB directly bind to the adhA promoter region, that RamA is essential for the expression of adhA, and that RamB exerts a negative control on adhA expression in the presence of glucose or acetate in the growth medium. However, since the glucose- and acetate-dependent down-regulation of adhA expression was only partially released in a RamB-deficient mutant, there might be an additional regulator involved in the catabolite repression of adhA.
机译：谷氨酸棒杆菌最近被证明可以在乙醇上生长，作为碳和能源，并且在这种底物上生长时具有高醇脱氢酶（ADH）活性，而在乙醇加葡萄糖或葡萄糖下生长时具有低ADH活性。单独。在这里，我们确定 C。谷氨酸 ADH基因（ adhA ），分析其转录组织，并研究乙酸代谢RamA和RamB的转录调控因子与 adhA 表达的相关性。 adhA 的序列分析预测，该多肽具有345个氨基酸，与I组的锌依赖性ADH酶显示高达57％的同一性。染色体 adhA 基因的失活导致不能在乙醇上生长并且没有ADH活性，这表明在C中仅存在一种乙醇氧化的ADH酶。谷氨酸。转录分析显示 C。谷氨酸adhA 基因是单顺反子，在生长培养基中存在葡萄糖和乙酸盐时其表达受到抑制，即 adhA 表达受到分解代谢物的抑制。进一步的分析表明，RamA和RamB直接与 adhA 启动子区域结合，RamA对 adhA 的表达必不可少，RamB对具有负调控作用。培养基中葡萄糖或乙酸盐存在下adhA 的表达但是，由于 adhA 表达的葡萄糖和乙酸盐依赖性下调仅在RamB缺陷型突变体中部分释放，因此可能存在其他调节剂参与 adhA的分解代谢抑制。

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