Prather Donald M, Larschan Erica, Winston Fred
Department of Genetics, Harvard Medical School, 77 Louis Pasteur Ave., Boston, MA 02115, USA.
Mol Cell Biol. 2005 Apr;25(7):2650-9. doi: 10.1128/MCB.25.7.2650-2659.2005.
TFIIS is a transcription elongation factor that has been extensively studied biochemically. Although the in vitro mechanisms by which TFIIS stimulates RNA transcript cleavage and polymerase read-through have been well characterized, its in vivo roles remain unclear. To better understand TFIIS function in vivo, we have examined its role during Gal4-mediated activation of the Saccharomyces cerevisiae GAL1 gene. Surprisingly, TFIIS is strongly associated with the GAL1 upstream activating sequence. In addition, TFIIS recruitment to Gal4-binding sites is dependent on Gal4, SAGA, and Mediator but not on RNA polymerase II (Pol II). The association of TFIIS is also necessary for the optimal recruitment of TATA-binding protein and Pol II to the GAL1 promoter. These results provide strong evidence that TFIIS plays an important role in the initiation of transcription at GAL1 in addition to its well-characterized roles in transcription elongation.
TFIIS是一种转录延伸因子，已对其进行了广泛的生化研究。尽管TFIIS刺激RNA转录本切割和聚合酶通读的体外机制已得到充分表征，但其在体内的作用仍不清楚。为了更好地理解TFIIS在体内的功能，我们研究了它在酵母GAL1基因的Gal4介导的激活过程中的作用。令人惊讶的是，TFIIS与GAL1上游激活序列紧密相关。此外，TFIIS募集到Gal4结合位点依赖于Gal4、SAGA和中介体，但不依赖于RNA聚合酶II（Pol II）。TFIIS的结合对于TATA结合蛋白和Pol II最佳募集到GAL1启动子也是必需的。这些结果提供了强有力的证据，表明TFIIS除了在转录延伸中具有充分表征的作用外，在GAL1转录起始中也起着重要作用。
