Koh S S, Ansari A Z, Ptashne M, Young R A
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
Mol Cell. 1998 May;1(6):895-904. doi: 10.1016/s1097-2765(00)80088-x.
Expression of protein-coding genes in eukaryotes involves the recruitment, by transcriptional activator proteins, of a transcription initiation apparatus consisting of greater than 50 polypeptides. Recent genetic and biochemical evidence in yeast suggests that a subset of these proteins, called SRB proteins, are likely targets for transcriptional activators. We demonstrate here, through affinity chromatography, photo-cross-linking, and surface plasmon resonance experiments, that the GAL4 activator interacts directly with the SRB4 subunit of the RNA polymerase II holoenzyme. The GAL4 activation domain binds to two essential segments of SRB4. The physiological relevance of this interaction is confirmed by mutations in SRB4, which occur within its GAL4-binding domain and which restore activation in vivo by a GAL4 derivative bearing a mutant activation domain.
真核生物中蛋白质编码基因的表达涉及转录激活蛋白招募一个由50多种多肽组成的转录起始装置。酵母中最近的遗传和生化证据表明，这些蛋白质中的一个子集，称为SRB蛋白，可能是转录激活因子的作用靶点。我们在此通过亲和层析、光交联和表面等离子体共振实验证明，GAL4激活因子直接与RNA聚合酶II全酶的SRB4亚基相互作用。GAL4激活结构域与SRB4的两个必需区段结合。SRB4中发生在其GAL4结合结构域内且通过带有突变激活结构域的GAL4衍生物在体内恢复激活的突变证实了这种相互作用的生理相关性。
