Nilsson A, Påhlman I L, Jovall P A, Blomberg A, Larsson C, Gustafsson L
Department of Cell and Molecular Biology, Göteborg University, Box 462, S-405 30 Göteborg, Sweden.
Yeast. 2001 Nov;18(15):1371-81. doi: 10.1002/yea.786.
A comparison of catabolic capacity was made between S. cerevisiae cells subjected to 24 h carbon or nitrogen starvation. The cells were shifted to starvation conditions at the onset of respiratory growth on ethanol in aerobic batch cultures, using glucose as the carbon and energy source. The results showed that the catabolic capacity was preserved to a much larger extent during carbon compared to nitrogen starvation. Nitrogen starvation experiments were made in the presence of ethanol (not glucose) to exclude the effect of glucose transport inactivation (Busturia and Lagunas, 1986). Hence, the difference in catabolic capacity could not be attributed to differences in glucose transport capacity during these conditions. In order to understand the reason for this difference in starvation response, measurement of protein composition, adenine nucleotides, inorganic phosphate, polyphosphate and storage carbohydrates were performed. No clear correlation between any of these variables and catabolic capacity after starvation could be obtained. However, there was a positive correlation between total catabolic activity and intracellular ATP concentration when glucose was added to starved cells. The possible mechanism for this correlation, as well as what determines the ATP level, is discussed.
对酿酒酵母细胞在经历24小时碳饥饿或氮饥饿后的分解代谢能力进行了比较。在需氧分批培养中，当细胞以乙醇为呼吸底物开始生长时，以葡萄糖作为碳源和能源，将细胞转移至饥饿条件下。结果表明，与氮饥饿相比，在碳饥饿期间分解代谢能力得到了更大程度的保留。氮饥饿实验是在乙醇（而非葡萄糖）存在的情况下进行的，以排除葡萄糖转运失活的影响（Busturia和Lagunas，1986年）。因此，在这些条件下，分解代谢能力的差异不能归因于葡萄糖转运能力的差异。为了理解饥饿反应中这种差异的原因，对蛋白质组成、腺嘌呤核苷酸、无机磷酸盐、多聚磷酸盐和储存碳水化合物进行了测量。饥饿后，这些变量与分解代谢能力之间均未获得明显的相关性。然而，当向饥饿细胞中添加葡萄糖时，总分解代谢活性与细胞内ATP浓度之间存在正相关。本文讨论了这种相关性的可能机制以及决定ATP水平的因素。
