Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 987696 Nebraska Medical Center, Omaha, NE 68198-7696, USA.
J Mol Biol. 2010 Mar 19;397(1):278-89. doi: 10.1016/j.jmb.2010.01.017. Epub 2010 Jan 15.
The Ets family of transcription factors is composed of more than 30 members. One of its members, Elf3, is expressed in virtually all epithelial cells as well as in many tumors, including breast tumors. Several studies observed that the promoter of the type II TGF-beta receptor gene (TbetaR-II) is strongly stimulated by Elf3 via two adjacent Elf3 binding sites, the A-site and the B-site. Here, we report the 2.2 A resolution crystal structure of a mouse Elf3 C-terminal fragment, containing the DNA-binding Ets domain, in complex with the B-site of mouse type II TGF-beta receptor promoter DNA (mTbetaR-II(DNA)). Elf3 contacts the core GGAA motif of the B-site from a major groove similar to that of known Ets proteins. However, unlike other Ets proteins, Elf3 also contacts sequences of the A-site from the minor groove of the DNA. DNA binding experiments and cell-based transcription studies indicate that minor groove interaction by Arg349 located in the Ets domain is important for Elf3 function. Equally interesting, previous studies have shown that the C-terminal region of Elf3, which flanks the Ets domain, is required for Elf3 binding to DNA. In this study, we determined that Elf3 amino acid residues within this flanking region, including Trp361, are important for the structural integrity of the protein as well as for the Efl3 DNA binding and transactivation activity.
Ets 转录因子家族由 30 多个成员组成。其成员之一 Elf3 在几乎所有上皮细胞以及许多肿瘤中表达，包括乳腺癌。有几项研究观察到，TGF-β 受体 II 型（TbetaR-II）基因的启动子可被 Elf3 通过两个相邻的 Elf3 结合位点 A 位和 B 位强烈激活。在此，我们报告了一个含有 DNA 结合 Ets 结构域的小鼠 Elf3 C 端片段与小鼠 II 型 TGF-β受体启动子 DNA（mTbetaR-II(DNA)）的 B 位的 2.2Å分辨率晶体结构。Elf3 从主沟与 B 位的核心 GGAA 基序接触，类似于已知的 Ets 蛋白。然而，与其他 Ets 蛋白不同，Elf3 还从 DNA 的小沟与 A 位的序列接触。DNA 结合实验和基于细胞的转录研究表明，位于 Ets 结构域中的 Arg349 的小沟相互作用对于 Elf3 功能很重要。同样有趣的是，先前的研究表明，Ets 结构域侧翼的 Elf3 C 端区域对于 Elf3 与 DNA 的结合至关重要。在这项研究中，我们确定了该侧翼区域内的 Elf3 氨基酸残基，包括 Trp361，对于蛋白质的结构完整性以及 Elf3 DNA 结合和转录激活活性都很重要。
