Bojunga N, Kötter P, Entian K D
Institut für Mikrobiologie, Johann Wolfgang Goethe-Universität, Frankfurt/Main, Germany.
Mol Gen Genet. 1998 Dec;260(5):453-61. doi: 10.1007/s004380050916.
The product of the ACR1 gene is essential for growth of Saccharomyces cerevisiae on ethanol or acetate as sole carbon source, and its expression is subject to glucose repression. It was previously shown that Acr1p is a membrane protein which specifically transports succinate and fumarate. Its suggested function is to shuttle cytosolic succinate from the glyoxylate cycle into the mitochondria in exchange for fumarate, an activity that is essential during gluconeogenic growth on C2 compounds. In this study we show that ACR1 is coregulated with the genes coding for the key enzymes of the glyoxylate cycle and gluconeogenesis: ICL1, MLS1 and PCK1, FBP1 respectively. We demonstrate that derepression of ACR1 is strictly dependent on the Zn2Cys6-type transcriptional activator Cat8p. A detailed deletion analysis of the ACR1 promoter revealed that 69% of the derepression of ACR1 is mediated by three cis-acting elements, located between positions -679 and -569 relative to the translational start, which show a high degree of similarity to the UAS/CSRE elements of PCK1, FBP1, ICL1 and MLS1. Our results, in conjunction with previous biochemical data, clearly identify Acr1p as an element which is directly involved in gluconeogenesis, functioning as the mitochondrial carrier which links the anaplerotic reactions of the glyoxylate cycle to the TCA cycle.
ACR1基因的产物对于酿酒酵母在以乙醇或乙酸盐作为唯一碳源的条件下生长至关重要，并且其表达受到葡萄糖抑制。先前的研究表明，Acr1p是一种膜蛋白，专门运输琥珀酸和富马酸。其推测的功能是将乙醛酸循环中的胞质琥珀酸穿梭到线粒体中，以交换富马酸，这种活性在以C2化合物进行糖异生生长过程中是必不可少的。在本研究中，我们表明ACR1与分别编码乙醛酸循环和糖异生关键酶的基因：ICL1、MLS1和PCK1、FBP1共同受到调控。我们证明ACR1的去阻遏严格依赖于Zn2Cys6型转录激活因子Cat8p。对ACR1启动子的详细缺失分析表明，ACR1去阻遏的69%是由三个顺式作用元件介导的，这些元件位于相对于翻译起始位点-679至-569的位置之间，与PCK1、FBP1、ICL1和MLS1的UAS/CSRE元件具有高度相似性。我们的结果与先前的生化数据相结合，明确将Acr1p鉴定为直接参与糖异生的一个元件，作为将乙醛酸循环的回补反应与三羧酸循环联系起来的线粒体载体发挥作用。
