Lagunas R, Dominguez C, Busturia A, Sáez M J
J Bacteriol. 1982 Oct;152(1):19-25. doi: 10.1128/jb.152.1.19-25.1982.
Saccharomyces cerevisiae does not show a noticeable Pasteur effect (activation of sugar catabolism by anaerobiosis) when growing with an excess of sugar and nitrogen source, but it does do so after exhaustion of the nitrogen source in the medium (resting state). We have found that this different behavior of growing and resting S. cerevisiae seems due to differences in the contribution of respiration to catabolism under both states. Growing S. cerevisiae respired only 3 to 20% of the catabolized sugar, depending on the sugar present; the remainder was fermented. In contrast, resting S. cerevisiae respired as much as 25 to 100% of the catabolized sugar. These results suggest that a shift to anaerobiosis would have much greater energetic consequences in resting than in growing S. cerevisiae. In resting S. cerevisiae anaerobiosis would strongly decrease the formation of ATP; as a consequence, various regulatory mechanisms would switch on, producing the observed increase of the rate of glycolysis. The greater significance that respiration reached in resting cells was not due to an increase of the respiratory capacity itself, but to a loss of fermentation which turned respiration into the main catabolic pathway. The main mechanism involved in the loss of fermentation observed during nitrogen starvation was a progressive inactivation of the sugar transport systems that reduced the rate of fermentation to less than 10% of the value observed in growing cells. Inactivation of the sugar transports seems a consequence of the turnover of the sugar carriers whose apparent half-lives were 2 to 7 h.
酿酒酵母在有过量糖和氮源的情况下生长时，不会表现出明显的巴斯德效应（厌氧状态激活糖分解代谢），但在培养基中的氮源耗尽后（静止状态）会表现出该效应。我们发现，酿酒酵母生长和静止状态下的这种不同行为似乎是由于两种状态下呼吸作用对分解代谢的贡献不同。生长中的酿酒酵母仅将3%至20%的分解代谢糖用于呼吸，具体比例取决于存在的糖；其余部分则被发酵。相比之下，静止的酿酒酵母将多达25%至100%的分解代谢糖用于呼吸。这些结果表明，向厌氧状态的转变在静止的酿酒酵母中产生的能量后果比在生长的酿酒酵母中要大得多。在静止的酿酒酵母中，厌氧状态会强烈降低ATP的形成；因此，各种调节机制会开启，导致观察到的糖酵解速率增加。呼吸作用在静止细胞中具有更大意义，并非由于呼吸能力本身的增加，而是由于发酵作用的丧失，这使得呼吸作用成为主要的分解代谢途径。在氮饥饿期间观察到的发酵作用丧失所涉及的主要机制是糖转运系统的逐渐失活，这将发酵速率降低至生长细胞中观察到的值的不到10%。糖转运的失活似乎是糖载体周转的结果，其表观半衰期为2至7小时。
