Mercado J J, Smith R, Sagliocco F A, Brown A J, Gancedo J M
Instituto de Investigaciones Biomédicas del Consejo Superior de Investigaciones Cientificas, Facultad de Medicina, Universidad Autónoma de Madrid, Spain.
Eur J Biochem. 1994 Sep 1;224(2):473-81. doi: 10.1111/j.1432-1033.1994.00473.x.
The FBP1 and PCK1 genes encode the gluconeogenic enzymes fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase, respectively. In the yeast, Saccharomyces cerevisiae, the corresponding mRNAs are present at low levels during growth on glucose, but are present at elevated levels during growth on gluconeogenic carbon sources. We demonstrate that the levels of the FBP1 and PCK1 mRNAs are acutely sensitive to the addition of glucose to the medium and that the levels of these mRNAs decrease rapidly when glucose is added to the medium at a concentration of only 0.005%. At this concentration, glucose blocks FBP1 and PCK1 transcription, but has no effect on iso-1 cytochrome c (CYC1) mRNA levels. Glucose also increases the rate of degradation of the PCK1 mRNA approximately twofold, but only has a slight effect upon FBP1 mRNA turnover. We show that the levels of the FBP1 and PCK1 mRNAs are also sensitive to other environmental factors. The levels of these mRNAs decrease transiently in response to a decrease of the pH from pH 7.5 to pH 6.5 in the medium, or to a mild temperature shock (from 24 degrees C to 36 degrees C). The latter response appears to be mediated by accelerated mRNA decay.
FBP1和PCK1基因分别编码糖异生酶1,6-二磷酸果糖磷酸酶和磷酸烯醇丙酮酸羧激酶。在酿酒酵母中，相应的mRNA在葡萄糖培养基中生长时含量较低，但在糖异生碳源培养基中生长时含量升高。我们证明，FBP1和PCK1 mRNA的水平对向培养基中添加葡萄糖极为敏感，当向培养基中添加仅0.005%浓度的葡萄糖时，这些mRNA的水平会迅速下降。在此浓度下，葡萄糖会阻断FBP1和PCK1的转录，但对同功酶1细胞色素c（CYC1）mRNA水平没有影响。葡萄糖还会使PCK1 mRNA的降解速率增加约两倍，但对FBP1 mRNA的周转只有轻微影响。我们表明，FBP1和PCK1 mRNA的水平对其他环境因素也很敏感。响应于培养基pH从7.5降至6.5或轻微温度冲击（从24℃至36℃），这些mRNA的水平会短暂下降。后一种反应似乎是由mRNA加速降解介导的。
