Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T1Z3, Canada.
Structure. 2010 Dec 8;18(12):1642-53. doi: 10.1016/j.str.2010.09.016.
DAXX is a scaffold protein with diverse roles including transcription and cell cycle regulation. Using NMR spectroscopy, we demonstrate that the C-terminal half of DAXX is intrinsically disordered, whereas a folded domain is present near its N terminus. This domain forms a left-handed four-helix bundle (H1, H2, H4, H5). However, due to a crossover helix (H3), this topology differs from that of the Sin3 PAH domain, which to date has been used as a model for DAXX. The N-terminal residues of the tumor suppressor Rassf1C fold into an amphipathic α helix upon binding this DAXX domain via a shallow cleft along the flexible helices H2 and H5 (K(D) ∼60 μM). Based on a proposed DAXX recognition motif as hydrophobic residues preceded by negatively charged groups, we found that peptide models of p53 and Mdm2 also bound the helical bundle. These data provide a structural foundation for understanding the diverse functions of DAXX.
DAXX 是一种支架蛋白，具有多种功能，包括转录和细胞周期调节。使用 NMR 光谱学，我们证明了 DAXX 的 C 端半部分是固有无序的，而在其 N 端附近存在一个折叠结构域。该结构域形成一个左手四螺旋束（H1、H2、H4、H5）。然而，由于交叉螺旋（H3）的存在，这种拓扑结构与迄今为止用作 DAXX 模型的 Sin3 PAH 结构域不同。肿瘤抑制因子 Rassf1C 的 N 端残基通过沿着柔性螺旋 H2 和 H5 的浅裂缝与该 DAXX 结构域结合，形成一个两亲性的α螺旋（K(D)∼60 μM）。基于一个提议的 DAXX 识别基序，即由带负电荷的基团前面的疏水性残基，我们发现 p53 和 Mdm2 的肽模型也与螺旋束结合。这些数据为理解 DAXX 的多种功能提供了结构基础。
