Wu Pei-Yun Jenny, Ruhlmann Christine, Winston Fred, Schultz Patrick
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mol Cell. 2004 Jul 23;15(2):199-208. doi: 10.1016/j.molcel.2004.06.005.
The Saccharomyces cerevisiae SAGA complex is a multifunctional coactivator that regulates transcription by RNA polymerase II. The 3D structure of SAGA, revealed by electron microscopy, is formed by five modular domains and shows a high degree of structural conservation to human TFTC, reflecting their related subunit composition. The positions of several SAGA subunits were mapped by immunolabeling and by analysis of mutant complexes. The Taf (TBP-associated factor) subunits, shared with TFIID, occupy a central region in SAGA and form a similar structure in both complexes. The locations of two histone fold-containing core subunits, Spt7 and Ada1, are consistent with their role in providing a SAGA-specific interface with the Tafs. Three components that perform distinct regulatory functions, Spt3, Gcn5, and Tra1, are spatially separated, underscoring the modular nature of the complex. Our data provide insights into the molecular architecture of SAGA and imply a functional organization to the complex.
酿酒酵母SAGA复合物是一种多功能共激活因子，可调节RNA聚合酶II的转录。通过电子显微镜揭示的SAGA的三维结构由五个模块化结构域组成，并且与人类TFTC具有高度的结构保守性，反映了它们相关的亚基组成。通过免疫标记和突变复合物分析确定了几个SAGA亚基的位置。与TFIID共享的Taf（TBP相关因子）亚基占据SAGA的中心区域，并在两种复合物中形成类似的结构。两个含组蛋白折叠的核心亚基Spt7和Ada1的位置与其在提供与Tafs的SAGA特异性界面中的作用一致。执行不同调节功能的三个组分Spt3、Gcn5和Tra1在空间上是分开的，突出了该复合物的模块化性质。我们的数据提供了对SAGA分子结构的见解，并暗示了该复合物的功能组织。
