Chen J L, Attardi L D, Verrijzer C P, Yokomori K, Tjian R
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720-3202.
Cell. 1994 Oct 7;79(1):93-105. doi: 10.1016/0092-8674(94)90403-0.
We previously reported that transcriptional regulators can bind selected TAF subunits of the TFIID complex. However, the specificity and function of individual TAFs in mediating transcriptional activation remained unknown. Here we report the in vitro assembly and transcriptional properties of TBP-TAF complexes reconstituted from the nine recombinant subunits of Drosophila TFIID. A minimal complex containing TBP and TAFII250 directs basal but not activator-responsive transcription. By contrast, reconstituted holo-TFIID supports activation by an assortment of activators. The activator NTF-1, which binds TAFII150, stimulates transcription with a complex containing only TBP, TAFII250, and TAFII150, whereas Sp1 binds and additionally requires TAFII110 for activation. Interestingly, TAFII150 enhances Sp1 activation even though this subunit does not bind directly to Sp1. These results establish that specific subcomplexes of TFIID can mediate activation by different classes of activators and suggest that TAFs perform multiple functions during activation.
我们之前报道过转录调节因子能够结合TFIID复合物中特定的TAF亚基。然而，单个TAF在介导转录激活过程中的特异性和功能仍不清楚。在此，我们报道了从果蝇TFIID的九个重组亚基重构的TBP-TAF复合物的体外组装及转录特性。包含TBP和TAFII250的最小复合物可指导基础转录，但不能指导激活剂响应转录。相比之下，重构的全酶TFIID支持多种激活剂的激活作用。结合TAFII150的激活剂NTF-1，可通过仅包含TBP、TAFII250和TAFII150的复合物刺激转录，而Sp1结合并激活还需要TAFII110。有趣的是，尽管TAFII150并不直接与Sp1结合，但它能增强Sp1的激活作用。这些结果表明，TFIID的特定亚复合物可介导不同类型激活剂的激活作用，并提示TAF在激活过程中发挥多种功能。
