Gill G, Ptashne M
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
Nature. 1988 Aug 25;334(6184):721-4. doi: 10.1038/334721a0.
The yeast transcriptional activator GAL4 binds specific sites on DNA to activate transcription of adjacent genes. The distinct activating regions of GAL4 are rich in acidic residues and it has been suggested that these regions interact with another protein component of the transcriptional machinery (such as the TATA-binding protein or RNA polymerase II) while the DNA-binding region serves to position the activating region near the gene. Here we show that various GAL4 derivatives, when expressed at high levels in yeast, inhibit transcription of certain genes lacking GAL4 binding sites, that more efficient activators inhibit more strongly and that inhibition does not depend on the DNA-binding domain. We suggest that this inhibition, which we call squelching, reflects titration of a transcription factor by the activating region of GAL4.
酵母转录激活因子GAL4结合DNA上的特定位点以激活相邻基因的转录。GAL4不同的激活区域富含酸性残基，有人提出这些区域与转录机制的另一种蛋白质成分（如TATA结合蛋白或RNA聚合酶II）相互作用，而DNA结合区域则将激活区域定位在基因附近。在此我们表明，各种GAL4衍生物在酵母中高水平表达时，会抑制某些缺乏GAL4结合位点的基因的转录，更有效的激活因子抑制作用更强，且抑制作用不依赖于DNA结合结构域。我们认为这种抑制作用，我们称之为“压制”，反映了GAL4激活区域对转录因子的滴定作用。
