Kulesza Caroline A, Van Buskirk Heather A, Cole Michael D, Reese Joseph C, Smith M Mitchell, Engel Daniel A
Department of Microbiology and Cancer Center, University of Virginia School of Medicine, Charlottesville, Virginia, VA 22908, USA.
Oncogene. 2002 Feb 21;21(9):1411-22. doi: 10.1038/sj.onc.1205201.
The budding yeast Saccharomyces cerevisiae was used as a model system to study the function of the adenovirus E1A oncoprotein. Previously we demonstrated that expression of the N-terminal 82 amino acids of E1A in yeast causes pronounced growth inhibition and specifically interferes with SWI/SNF-dependent transcriptional activation. Further genetic analysis identified the yeast transcription factor Adr1 as a high copy suppressor of E1A function. Transcriptional activation by Adr1 requires interaction with co-activator proteins Ada2 and Gcn5, components of histone acetyltransferase complexes including ADA and SAGA. Analysis of mutant alleles revealed that several components of the SAGA complex, including proteins from the Ada, Spt, and Taf classes were required for E1A-induced growth inhibition. Growth inhibition also depended on the Gcn5 histone acetyltransferase, and point mutations within the Gcn5 HAT domain rendered cells E1A-resistant. Also required was SAGA component Tra1, a homologue of the mammalian TRRAP protein which is required for c-myc and E1A induced cellular transformation. Additionally, Gcn5 protein could associate with E1A in vitro in a manner that depended on the N-terminal domain of E1A, and Tra1 protein was co-immunoprecipitated with E1A in vivo. These results indicate a strong requirement for intact SAGA complex for E1A to function in yeast, and suggest a role for SAGA-like complexes in mammalian cell transformation.
出芽酵母酿酒酵母被用作研究腺病毒E1A癌蛋白功能的模型系统。此前我们证明，在酵母中表达E1A的N端82个氨基酸会导致明显的生长抑制，并特异性干扰SWI/SNF依赖的转录激活。进一步的遗传分析确定酵母转录因子Adr1是E1A功能的高拷贝抑制因子。Adr1的转录激活需要与共激活蛋白Ada2和Gcn5相互作用，Ada2和Gcn5是包括ADA和SAGA在内的组蛋白乙酰转移酶复合物的组成部分。对突变等位基因的分析表明，SAGA复合物的几个组分，包括来自Ada、Spt和Taf类别的蛋白质，是E1A诱导的生长抑制所必需的。生长抑制也依赖于Gcn5组蛋白乙酰转移酶，Gcn5 HAT结构域内的点突变使细胞对E1A产生抗性。还需要SAGA组分Tra1，它是哺乳动物TRRAP蛋白的同源物，c-myc和E1A诱导的细胞转化需要TRRAP蛋白。此外，Gcn5蛋白在体外可以以依赖于E1A N端结构域的方式与E1A结合，Tra1蛋白在体内与E1A共免疫沉淀。这些结果表明，完整的SAGA复合物是E1A在酵母中发挥功能所必需的，并提示SAGA样复合物在哺乳动物细胞转化中起作用。
