Braus G, Mösch H U, Vogel K, Hinnen A, Hütter R
Microbiological Institute, Swiss Federal Institute of Technology, Zürich.
EMBO J. 1989 Mar;8(3):939-45. doi: 10.1002/j.1460-2075.1989.tb03455.x.
Two regulatory proteins, PHO2 and the general control regulator GCN4, bind in vitro to the promoter of the tryptophan biosynthetic TRP4 gene; the TRP4 gene product catalyses the phosphoribosylation of anthranilate. PHO2 binds specifically to the TRP4 promoter, but does not bind to any other TRP promoter. PHO2 and GCN4 proteins bind in a mutually exclusive manner to the same sequence, UAS1, one of two GCN4 binding sites in the TRP4 promoter. UAS1 is the major site for GCN4-dependent TRP4 activation. The second GCN4 binding site, UAS2, interacts with GCN4 alone. PHO2 binding interferes with the general control response of TRP4 under low phosphate conditions and simultaneous amino acid starvation and thus the PHO2 regulatory protein connects phosphate metabolism and amino acid biosynthesis in yeast. The GCN4 protein mediates the response of the transcriptional apparatus to the environmental signal 'amino acid limitation', while PHO2 seems to be the phosphate sensor that adjusts the response to the availability of phosphate precursors.
两种调节蛋白，PHO2和通用控制调节因子GCN4，在体外与色氨酸生物合成TRP4基因的启动子结合；TRP4基因产物催化邻氨基苯甲酸的磷酸核糖基化。PHO2特异性结合TRP4启动子，但不与任何其他TRP启动子结合。PHO2和GCN4蛋白以互斥的方式结合到同一序列UAS1上，UAS1是TRP4启动子中两个GCN4结合位点之一。UAS1是GCN4依赖的TRP4激活的主要位点。第二个GCN4结合位点UAS2仅与GCN4相互作用。在低磷酸盐条件以及同时存在氨基酸饥饿的情况下，PHO2的结合会干扰TRP4的通用控制反应，因此PHO2调节蛋白将酵母中的磷酸盐代谢与氨基酸生物合成联系起来。GCN4蛋白介导转录装置对环境信号“氨基酸限制”的反应，而PHO2似乎是调节对磷酸盐前体可用性反应的磷酸盐传感器。
