McBride H J, Yu Y, Stillman D J
Division of Molecular Biology and Genetics, Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA.
J Biol Chem. 1999 Jul 23;274(30):21029-36. doi: 10.1074/jbc.274.30.21029.
Swi5 and Ace2 are cell cycle-regulated transcription factors that activate expression of early G(1)-specific genes in Saccharomyces cerevisiae. Swi5 and Ace2 have zinc finger DNA-binding domains that are highly conserved, and the two proteins bind to the same DNA sequences in vitro. Despite this similarity in DNA binding, Swi5 and Ace2 activate different genes in vivo, with Swi5 activating the HO gene and Ace2 activating CTS1 expression. In this report we have used chimeric fusions between Swi5 and Ace2 to determine what regions of these proteins are necessary for promoter-specific activation of HO and CTS1. We have identified specific regions of Swi5 and Ace2 that are required for activation of HO and CTS1, respectively. The Swi5 protein binds HO promoter DNA cooperatively with the Pho2 homeodomain protein, and the HO specificity region of Swi5 identified in the chimeric analysis coincides with the region of Swi5 previously identified that interacts with Pho2 in vitro. Swi5 and Ace2 also activate expression of a number of other genes expressed in G(1) phase of the cell cycle, including ASH1, CDC6, EGT2, PCL2, PCL9, RME1, and SIC1. Analysis of the Swi5/Ace2 chimeras shows that distinct regions of Swi5 and Ace2 contribute to the transcriptional activation of some of these other G(1)-regulated genes.
Swi5和Ace2是细胞周期调控的转录因子，可激活酿酒酵母中早期G1期特异性基因的表达。Swi5和Ace2具有高度保守的锌指DNA结合结构域，并且这两种蛋白质在体外可结合相同的DNA序列。尽管在DNA结合方面存在这种相似性，但Swi5和Ace2在体内激活不同的基因，Swi5激活HO基因，Ace2激活CTS1的表达。在本报告中，我们利用Swi5和Ace2之间的嵌合融合来确定这些蛋白质的哪些区域对于HO和CTS1的启动子特异性激活是必需的。我们已经分别鉴定出Swi5和Ace2中激活HO和CTS1所需的特定区域。Swi5蛋白与Pho2同源结构域蛋白协同结合HO启动子DNA，并且在嵌合分析中鉴定出的Swi5的HO特异性区域与先前在体外鉴定出的与Pho2相互作用的Swi5区域一致。Swi5和Ace2还激活细胞周期G1期表达的许多其他基因的表达，包括ASH1、CDC6、EGT2、PCL2、PCL9、RME1和SIC1。对Swi5/Ace2嵌合体的分析表明，Swi5和Ace2的不同区域对这些其他G1期调控基因中的一些基因的转录激活有贡献。
