Dekker N, Cox M, Boelens R, Verrijzer C P, van der Vliet P C, Kaptein R
Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands.
Nature. 1993 Apr 29;362(6423):852-5. doi: 10.1038/362852a0.
The transcription factor Oct-1 belongs to a family containing a POU DNA-binding domain. This bipartite domain is composed of a POU-specific domain (POUs) and a POU-homeodomain (POUhd) connected by a flexible linker. The left half of the optimal POU binding site, the octamer ATGCAAAT, is recognized by POUs and the right half by POUhd. We have determined the solution structure of POUs by nuclear magnetic resonance. It consists of four alpha-helices connected by short loops. Helices I and IV are in a parallel coiled-coil arrangement. The folding topology appears to be similar to that of the bacteriophage lambda-repressor and 434 repressor. For the well defined parts of the protein (residues 1-71), the average root-mean square deviation for the backbone atoms is 0.9 A. Based on the observed selective exchange broadening in the (15N,1H)-HMQC (heteronuclear multiple quantum coherence) spectrum of the POUs-DNA complex we conclude that DNA-binding is mediated by helix III. We propose a model for the POU-DNA complex in which both recognition helices from the two subdomains have adjacent positions in the major groove.
转录因子Oct-1属于一个包含POU DNA结合结构域的家族。这个双结构域由一个POU特异性结构域（POUs）和一个通过柔性连接子相连的POU同源结构域（POUhd）组成。最佳POU结合位点的左半部分，即八聚体ATGCAAAT，由POUs识别，右半部分由POUhd识别。我们通过核磁共振确定了POUs的溶液结构。它由四个通过短环连接的α螺旋组成。螺旋I和IV呈平行卷曲螺旋排列。其折叠拓扑结构似乎与噬菌体λ阻遏蛋白和434阻遏蛋白的相似。对于蛋白质定义明确的部分（残基1 - 71），主链原子的平均均方根偏差为0.9埃。基于在POUs - DNA复合物的（15N，1H）-HMQC（异核多量子相干）谱中观察到的选择性交换加宽，我们得出DNA结合是由螺旋III介导的结论。我们提出了一个POU - DNA复合物模型，其中来自两个亚结构域的识别螺旋在大沟中具有相邻位置。
