Phosphoenolpyruvate synthetase and pyruvate, phosphate dikinase of Thermoproteus tenax:: key pieces in the puzzle of archaeal carbohydrate metabolism
Phosphoenolpyruvate synthetase and pyruvate, phosphate dikinase of Thermoproteus tenax:: key pieces in the puzzle of archaeal carbohydrate metabolism
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DOI：
10.1111/j.1365-2958.2006.05098.x
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Hensel, R
中科院分区：
文献类型：
--
作者：
Tjaden, B;Plagens, A;Hensel, R
磷酸烯醇丙酮酸和丙酮酸的相互转化是细菌和真核生物中 Embden-Meyerhof-Parnas (EMP) 途径的重要控制点，但人们对古细菌中的这一调节位点知之甚少。在这里，我们报告了磷酸烯醇丙酮酸合成酶（PEPS）和第一个描述的古细菌丙酮酸磷酸二激酶（PPDK）的共存，除了丙酮酸激酶（PK）之外，磷酸烯醇丙酮酸合成酶（PEPS）除了丙酮酸激酶（PK）之外，还参与了超嗜热crenarchaeote Thermoproteus tenax中的该反应的催化。对 T. tenax PEPS 和 PPDK 编码基因进行了克隆并在大肠杆菌中表达，并分析了重组基因产物的酶学和调控特性。 PEPS 催化丙酮酸单向转化为磷酸烯醇式丙酮酸，而 PPDK 显示出双向活性，优先进行分解代谢反应。 T. tenax 的 PK 在转录水平上受到调节，但在蛋白质水平上仅表现出有限的调节潜力，与之相反，PEPS 和 PPDK 活性受到磷酸腺苷和碳水化合物代谢中间体的调节。此外，如 Northern blot 分析所示，PEPS 的表达在转录水平上受到调节，以响应所提供的碳源。不同调节酶 PEPS、PPDK 和 PK 的联合作用代表了一种在可逆 EMP 途径中控制磷酸烯醇丙酮酸和丙酮酸相互转化的新方法，允许短期和长期适应不同的营养条件。比较基因组分析表明，PEPS、PPDK 和 PK 在其他古细菌中也共存，表明这些生物体中碳水化合物代谢具有类似的调节作用。
The interconversion of phosphoenolpyruvate and pyruvate represents an important control point of the Embden-Meyerhof-Parnas (EMP) pathway in Bacteria and Eucarya, but little is known about this site of regulation in Archaea. Here we report on the coexistence of phosphoenolpyruvate synthetase (PEPS) and the first described archaeal pyruvate, phosphate dikinase (PPDK), which, besides pyruvate kinase (PK), are involved in the catalysis of this reaction in the hyperthermophilic crenarchaeote Thermoproteus tenax. The genes encoding T. tenax PEPS and PPDK were cloned and expressed in Escherichia coli, and the enzymic and regulatory properties of the recombinant gene products were analysed. Whereas PEPS catalyses the unidirectional conversion of pyruvate to phosphoenolpyruvate, PPDK shows a bidirectional activity with a preference for the catabolic reaction. In contrast to PK of T. tenax, which is regulated on transcript level but exhibits only limited regulatory potential on protein level, PEPS and PPDK activities are modulated by adenosine phosphates and intermediates of the carbohydrate metabolism. Additionally, expression of PEPS is regulated on transcript level in response to the offered carbon source as revealed by Northern blot analyses. The combined action of the differently regulated enzymes PEPS, PPDK and PK represents a novel way of controlling the interconversion of phosphoenolpyruvate and pyruvate in the reversible EMP pathway, allowing short-term and long-term adaptation to different trophic conditions. Comparative genomic analyses indicate the coexistence of PEPS, PPDK and PK in other Archaea as well, suggesting a similar regulation of the carbohydrate metabolism in these organisms.