Hohmann S
Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven, Flanders, Belgium.
Mol Gen Genet. 1993 Dec;241(5-6):657-66. doi: 10.1007/BF00279908.
The regulatory gene PDC2 was identified in a screen for mutations affecting pyruvate decarboxylase activity in yeast. I have cloned and sequenced this gene. The predicted protein of 925 amino acids has no homology to any sequence in the databases. However, the protein sequence is rich in asparagine and serine residues, as is often found for transcriptional regulators. The PDC2 deletion mutant exhibits a phenotype very similar to, but more severe than that of the point mutant: a strongly reduced pyruvate decarboxylase specific activity, slow, respiration-dependent growth on glucose, and accumulation of pyruvate. The activity of other glycolytic enzymes seems to be unaffected by the pdc2 delta mutation. Synthesis of pyruvate decarboxylase is regulated by PDC2 at the transcriptional level. Expression of the major structural gene for pyruvate decarboxylase, PDC1, is strongly reduced in pdc2 delta mutants. Transcription of the generally more weakly expressed PDC5 gene appears to be entirely abolished. However, glucose induction of pyruvate decarboxylase synthesis is unaffected. Thus, PDC2 is either important for a high basal level of PDC gene expression or it plays a positive role in the autoregulation that controls expression of PDC1 and PDC5.
在一项针对影响酵母中丙酮酸脱羧酶活性的突变体筛选中，鉴定出了调控基因PDC2。我已克隆并测序了该基因。预测的含925个氨基酸的蛋白质与数据库中的任何序列均无同源性。然而，该蛋白质序列富含天冬酰胺和丝氨酸残基，转录调节因子通常如此。PDC2缺失突变体表现出与点突变体非常相似但更为严重的表型：丙酮酸脱羧酶比活性大幅降低，在葡萄糖上生长缓慢且依赖呼吸，丙酮酸积累。其他糖酵解酶的活性似乎不受pdc2δ突变的影响。丙酮酸脱羧酶的合成在转录水平受PDC2调控。丙酮酸脱羧酶主要结构基因PDC1在pdc2δ突变体中的表达大幅降低。通常表达较弱的PDC5基因的转录似乎完全被消除。然而，丙酮酸脱羧酶合成的葡萄糖诱导不受影响。因此，PDC2对于PDC基因的高基础表达水平很重要，或者它在控制PDC1和PDC5表达的自动调节中起积极作用。
