Structure of Pit-1 POU domain bound to DNA as a dimer: Unexpected arrangement and flexibility
Structure of Pit-1 POU domain bound to DNA as a dimer: Unexpected arrangement and flexibility
复制标题
DOI：
10.1101/gad.11.2.198
复制
发表时间：
1997-01-15
影响因子：
10.5
通讯作者：
Aggarwal, AK
中科院分区：
文献类型：
--
作者：
Jacobson, EM;Li, P;Aggarwal, AK
Pit-1是转录因子POU结构域家族的成员，其特征在于具有二分DNA结合结构域，基于与其靶基因中的不同DNA元件的结合而发挥关键的发育功能。在这里，我们报告了一个高分辨率的X-射线分析的Pit-1 POU域绑定到一个DNA元件作为一个同源二聚体。该分析揭示了Pit-1亚结构域与DNA的垂直面结合，而不是像Oct-1那样与DNA的相对面结合。这是通过POU特异性结构域的不同间距和方向来实现的。与先前的预测相反，二聚化界面涉及同源结构域的DNA识别螺旋的羧基末端，其在延伸的构象中与螺旋α 1的氨基末端处和对称性相关单体的POU特异性结构域的螺旋α 3和α 4之间的环中的特定残基相互作用。这些特征提示了Pit-1致病突变的分子基础，并为靶基因激活过程中蛋白质结构域与DNA位点之间的柔性变构提供了潜在依据。
Pit-1, a member of the POU domain family of transcription factors, characterized by a bipartite DNA-binding domain, serves critical developmental functions based on binding to diverse DNA elements in its target genes. Here we report a high resolution X-ray analysis of the Pit-1 POU domain bound to a DNA element as a homodimer. This analysis reveals that Pit-1 subdomains bind to perpendicular faces of the DNA, rather than opposite faces of the DNA as in Oct-1. This is accomplished by different spacing and orientation of the POU-specific domain. Contrary to previous predictions, the dimerization interface involves the carboxyl terminus of the DNA recognition helix of the homeodomain, which in an extended conformation interacts with specific residues at the amino terminus of helix alpha 1 and in the loop between helices alpha 3 and alpha 4 of the POU-specific domain of the symmetry related monomer. These features suggest the molecular basis of disease-causing mutations in Pit-1 and provide potential basis for the flexible allostery between protein domains and DNA sites in the activation of target genes.