Seeboth P G, Bohnsack K, Hollenberg C P
Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Federal Republic of Germany.
J Bacteriol. 1990 Feb;172(2):678-85. doi: 10.1128/jb.172.2.678-685.1990.
The PDC1 gene coding for a pyruvate decarboxylase (PDC; EC 4.1.1.1) was deleted from the Saccharomyces cerevisiae genome. The resulting pdc1(0) mutants were able to grow on glucose and still contained 60 to 70% of the wild-type PDC activity. Two DNA fragments with sequences homologous to that of the PDC1 gene were cloned from the yeast genome. One of the cloned genes (PDC5) was expressed at high rates predominantly in pdc1(0) strains and probably encodes the remaining PDC activity in these strains. Expression from the PDC1 promoter in PDC1 wild-type and pdc1(0) strains was examined by the use of two reporter genes. Deletion of PDC1 led to increased expression of the two reporter genes regardless of whether the fusions were integrated into the genome or present on autonomously replicating plasmids. The results suggested that this effect was due to feedback regulation of the PDC1 promoter-driven expression in S. cerevisiae pdc1(0) strains. The yeast PDC1 gene was expressed in Escherichia coli, leading to an active PDC. This result shows that the PDC1-encoded subunit alone can form an active tetramer without yeast-specific processing steps.
编码丙酮酸脱羧酶（PDC；EC 4.1.1.1）的PDC1基因已从酿酒酵母基因组中删除。由此产生的pdc1(0)突变体能够在葡萄糖上生长，并且仍含有60%至70%的野生型PDC活性。从酵母基因组中克隆了两个与PDC1基因序列同源的DNA片段。其中一个克隆基因（PDC5）主要在pdc1(0)菌株中高表达，可能编码这些菌株中剩余的PDC活性。通过使用两个报告基因检测了PDC1野生型和pdc1(0)菌株中PDC1启动子的表达。无论融合基因是整合到基因组中还是存在于自主复制质粒上，PDC1的缺失都会导致两个报告基因的表达增加。结果表明，这种效应是由于酿酒酵母pdc1(0)菌株中PDC1启动子驱动的表达受到反馈调节。酵母PDC1基因在大肠杆菌中表达，产生了有活性的PDC。这一结果表明，仅由PDC1编码的亚基就能形成有活性的四聚体，而无需酵母特异性加工步骤。
