Morita E H, Shirakawa M, Hayashi F, Imagawa M, Kyogoku Y
Institute for Protein Research, Osaka University, Japan.
Protein Sci. 1995 Apr;4(4):729-39. doi: 10.1002/pro.5560040412.
The POU-homeodomain (POUH) forms the bipartite DNA-binding POU domain in association with the POU-specific domain. The 1H, 15N, and 13C magnetic resonances of the 67-amino acid long POUH of mouse Oct-3 have almost completely been assigned, mainly through the combined use of three-dimensional triple resonance NMR methods. Based on the distance and dihedral angle constraints derived from the NMR data, the solution structure of the POUH domain has been calculated by the ab initio simulated annealing method. The average RMS deviation for all backbone heavy atoms of the 20 best calculated structures for residues 9-53 of the total 67 amino acid residues is 0.44 A. The POUH domain consists of three alpha-helices (helix-I, 10-20; helix-II, 28-38; and helix-III, 42-53), and helices-II and -III form a helix-turn-helix motif. In comparison with other classical homeodomains, the folding of the three helices is quite similar. However, the length of helix-III is fairly short. In the complex of the Oct-1 POU domain with an octamer site (Klemm JD, et al., 1994, Cell 77:21-32), the corresponding region is involved in helix-III. The structural difference between these two cases will be discussed.
POU 同源结构域（POUH）与 POU 特异性结构域结合形成二分体 DNA 结合 POU 结构域。小鼠 Oct-3 的 67 个氨基酸长的 POUH 的 1H、15N 和 13C 磁共振几乎已完全归属，主要通过三维三重共振 NMR 方法的联合使用。基于从 NMR 数据得出的距离和二面角约束，通过从头算模拟退火方法计算了 POUH 结构域的溶液结构。在总共 67 个氨基酸残基中，9 - 53 位残基的 20 个最佳计算结构的所有主链重原子的平均均方根偏差为 0.44 Å。POUH 结构域由三个α螺旋（螺旋 - I，10 - 20；螺旋 - II，28 - 38；和螺旋 - III，42 - 53）组成，螺旋 - II 和 - III 形成螺旋 - 转角 - 螺旋基序。与其他经典同源结构域相比，这三个螺旋的折叠非常相似。然而，螺旋 - III 的长度相当短。在 Oct - 1 POU 结构域与八聚体位点的复合物中（Klemm JD 等人，1994 年，《细胞》77:21 - 32），相应区域涉及螺旋 - III。将讨论这两种情况之间的结构差异。
