Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae
Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae
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DOI：
10.1128/aem.70.9.5323-5330.2004
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发表时间：
2004-09-01
影响因子：
4.4
通讯作者：
Gustafsson, L
中科院分区：
文献类型：
--
作者：
Elbing, K;Larsson, C;Gustafsson, L
在外部葡萄糖浓度高的情况下，酵母酿酒酵母主要将葡萄糖发酵成乙醇，而不考虑氧气的存在。相反，在低外部葡萄糖浓度和氧气存在的情况下，如在限制葡萄糖的化学调节剂中，不产生乙醇。外部葡萄糖浓度的重要性表明，酵母葡萄糖转运蛋白的亲和力和最大转运速率在乙醇生产的控制中起着核心作用。在这里，我们提出了一系列在己糖转运体Hxt1和Hxt7之间产生功能性嵌合体的菌株，每一个都具有不同的葡萄糖转运特性。菌株显示出糖酵解速率的下降范围，导致乙醇产量成比例下降。利用这些菌株，我们首次发现在高葡萄糖水平下，野生型酿酒酵母的葡萄糖摄取能力在指数批生长过程中不控制糖酵解通量。相比之下，我们的嵌合Hxt转运体在很大程度上控制了糖酵解的速率。由这些嵌合转运体介导葡萄糖摄取的菌株无疑将为详细研究酿酒酵母发酵和呼吸转换的机制提供有力的工具，并将为工业发酵的控制提供新的工具。
The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycollytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycollysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations.