Giniger E, Varnum S M, Ptashne M
Cell. 1985 Apr;40(4):767-74. doi: 10.1016/0092-8674(85)90336-8.
We show by the following series of experiments that the yeast positive regulatory protein GAL4 binds to four sites in the upstream activating sequence UASG to activate transcription of the adjacent GAL1 and GAL10 genes. GAL4 protein expressed in E. coli protected guanine residues in UASG from methylation by dimethyl sulfate. The same set of protections was seen in vivo in yeast and depended on the GAL4+ allele. This protection pattern is consistent with the idea that GAL4 protein binds to four related 17 bp sequences, each of which displays approximate 2-fold rotational symmetry. A single near-consensus synthetic 17 bp oligonucleotide, installed in front of the yeast GAL1 or CYC1 transcription units, conferred a high level of galactose inducibility upon these genes. Further experiments suggest that one mechanism of glucose repression is inhibition of the binding of GAL4 protein to DNA.
我们通过以下一系列实验表明，酵母正调控蛋白GAL4与上游激活序列UASG中的四个位点结合，以激活相邻的GAL1和GAL10基因的转录。在大肠杆菌中表达的GAL4蛋白保护UASG中的鸟嘌呤残基不被硫酸二甲酯甲基化。在酵母体内也观察到了相同的保护模式，且依赖于GAL4 +等位基因。这种保护模式与GAL4蛋白结合四个相关的17bp序列的观点一致，每个序列都显示出近似2倍的旋转对称性。一个单一的近共识合成17bp寡核苷酸，安装在酵母GAL1或CYC1转录单元之前，赋予这些基因高水平的半乳糖诱导性。进一步的实验表明，葡萄糖阻遏的一种机制是抑制GAL4蛋白与DNA的结合。
