ALTERATION OF GROWTH-YIELD BY OVEREXPRESSION OF PHOSPHOENOLPYRUVATE CARBOXYLASE AND PHOSPHOENOLPYRUVATE CARBOXYKINASE IN ESCHERICHIA-COLI
ALTERATION OF GROWTH-YIELD BY OVEREXPRESSION OF PHOSPHOENOLPYRUVATE CARBOXYLASE AND PHOSPHOENOLPYRUVATE CARBOXYKINASE IN ESCHERICHIA-COLI
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DOI：
10.1128/aem.59.12.4261-4265.1993
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发表时间：
1993-12-01
影响因子：
4.4
通讯作者：
LIAO, JC
中科院分区：
文献类型：
--
作者：
CHAO, YP;LIAO, JC
磷酸烯醇丙酮酸和草酰乙酸是分解代谢和生物合成之间的关键中间体。这些分支点的碳变化将影响生长产量和产物的形成。我们尝试通过在tac启动子的控制下从多拷贝质粒过度表达磷酸烯醇丙酮酸羧化酶和磷酸烯醇丙酮酸羧激酶来调节磷酸烯醇丙酮酸和草酰乙酸之间的代谢流。研究发现，磷酸烯醇丙酮酸羧化酶的过度表达降低了葡萄糖消耗和有机酸排泄的速率，但生长和呼吸速率保持不变。因此，葡萄糖的生长产率得到提高。该结果表明，磷酸烯醇丙酮酸羧化酶的野生型水平对于分批培养物中最有效的葡萄糖利用而言并不是最佳的。另一方面，相对于生长所需的水平，磷酸烯醇丙酮酸羧激酶的过度表达增加了葡萄糖消耗并减少了氧消耗。因此，由于发酵产物排泄率较高，葡萄糖的生长产量降低。这些数据为中枢代谢的调节提供了有用的见解，并有助于进一步操纵代谢物产生的途径。
Phosphoenolpyruvate and oxaloacetate are key intermediates at the junction between catabolism and biosynthesis. Alteration of carbon How at these branch points will affect the growth yield and the formation of products. We attempted to modulate the metabolic flow between phosphoenolpyruvate and oxaloacetate by overexpressing phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase from a multicopy plasmid under the control of the tac promoter. It was found that overexpression of phosphoenolpyruvate carboxylase decreased the rates of glucose consumption and organic acid excretion, but the growth and respiration rates remained unchanged. Consequently, the growth yield on glucose was improved. This result indicates that the wild-type level of phosphoenolpyruvate carboxylase is not optimal for the most efficient glucose utilization in batch cultures. On the other hand, overexpression of phosphoenolpyruvate carboxykinase increased glucose consumption and decreased oxygen consumption relative to those levels required for growth. Therefore, the growth yield on glucose was reduced because of a higher rate of fermentation product excretion. These data provide useful insights into the regulation of central metabolism and facilitate further manipulation of pathways for metabolite production.