Homeostatic adjustment and metabolic remodeling in glucose-limited yeast cultures
Homeostatic adjustment and metabolic remodeling in glucose-limited yeast cultures
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DOI：
10.1091/mbc.e04-11-0968
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发表时间：
2005-05-01
影响因子：
3.3
通讯作者：
Botstein, D
中科院分区：
文献类型：
--
作者：
Brauer, MJ;Saldanha, AJ;Botstein, D
我们研究了葡萄糖限制在批量和稳态（恒化器）培养的酿酒酵母的基因表达的全球模式的生理反应。酵母的葡萄糖限制性分批培养物经历两个连续的指数生长阶段，开始于大部分发酵阶段，随后是基本上完全好氧使用残余葡萄糖和产生的乙醇。从基因表达的模式判断，在葡萄糖限制恒化器中稳定生长的细胞状态与在分批培养中细胞在经历这种“二次转变”之前的状态最接近。“基本上相同的模式被发现在恒化器之间具有五倍的稳态生长率差异（较低的速率接近分批培养中的第二阶段呼吸生长率）。虽然在这两种情况下，恒化器中的细胞消耗了大部分葡萄糖，但在这两种情况下，它们似乎都没有主要通过呼吸代谢葡萄糖。虽然有一些适度的氧化应激反应的迹象，恒化培养物没有表现出大量的环境应激反应与饥饿，也观察到，至少部分，在分批培养物中的二次转换。我们的结论是，尽管在葡萄糖稀缺的条件下，在恒化器中葡萄糖的完全有氧代谢的切换的理论可能性，稳态机制能够进行代谢调节，好像葡萄糖的发酵是优选的选择，直到葡萄糖完全耗尽。这些结果表明，某些方面的实际饥饿，可能是应激反应的一个组成部分，可能需要触发代谢重塑与diauxic转变。
We studied the physiological response to glucose limitation in batch and steady-state (chemostat) cultures of Saccharomyces cerevisiae by following global patterns of gene expression. Glucose-limited batch cultures of yeast go through two sequential exponential growth phases, beginning with a largely fermentative phase, followed by an essentially completely aerobic use of residual glucose and evolved ethanol. Judging from the patterns of gene expression, the state of the cells growing at steady state in glucose-limited chemostats corresponds most closely with the state of cells in batch cultures just before they undergo this "diauxic shift." Essentially the same pattern was found between chemostats having a fivefold difference in steady-state growth rate (the lower rate approximating that of the second phase respiratory growth rate in batch cultures). Although in both cases the cells in the chemostat consumed most of the glucose, in neither case did they seem to be metabolizing it primarily through respiration. Although there was some indication of a modest oxidative stress response, the chemostat cultures did not exhibit the massive environmental stress response associated with starvation that also is observed, at least in part, during the diauxic shift in batch cultures. We conclude that despite the theoretical possibility of a switch to fully aerobic metabolism of glucose in the chemostat under conditions of glucose scarcity, homeostatic mechanisms are able to carry out metabolic adjustment as if fermentation of the glucose is the preferred option until the glucose is entirely depleted. These results suggest that some aspect of actual starvation, possibly a component of the stress response, may be required for triggering the metabolic remodeling associated with the diauxic shift.