Isolated c-terminal domain of ring 1B is a dimer made of stable, well-structured monomerst
Isolated c-terminal domain of ring 1B is a dimer made of stable, well-structured monomerst
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DOI：
10.1021/bi701343q
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发表时间：
2007-11-06
期刊：
影响因子：
2.9
通讯作者：
Neira, José L.
中科院分区：
文献类型：
--
作者：
Czypionka, Anna;Paños, Olga Ruiz De Los;Neira, José L.
Ring1B 是 PRC1（多梳抑制复合物 1）的核心亚基蛋白，在同源框基因表达、X 染色体失活、干细胞自我更新和肿瘤发生的调节中发挥关键作用。 Ring1B 的 C 末端区域与 RYBP（瞬时转染细胞中的一种转录抑制因子）相互作用，并且还与 M33（另一种参与中胚层模式形成的转录抑制因子）相互作用。在这项工作中，我们通过 NMR、ITC 和分析凝胶过滤表明，Ring1B 的 C 端结构域 C-Ring1B 在溶液中是二聚体，解离常数为 200 μM。每种单体在较宽的 pH 范围内（类似于 298 K 下的 5 kcal mol(-1)）在生理条件下都很稳定，具有良好形成的核心和球形。 FTIR光谱表明，该二聚体具有高含量的α螺旋和β折叠，并且是由预先形成的折叠单体相互对接形成的。由于 C 末端区域对于 PRC1 与其他蛋白质的相互作用非常重要，因此二聚化和这些结构良好的单体的存在可能是一种调节形式。
The Ring1B is a core subunit protein of the PRC1 (polycomb repressive complex 1), which plays key roles in the regulation of the Homeobox gene expression, X-chromosome inactivation, stem cell self-renewal, and tumorigenesis. The C-terminal region of Ring1B interacts with RYBP, a transcriptional repressor in transiently transfected cells, and also with M33, another transcriptional repressor involved in mesoderm patterning. In this work, we show that the C-terminal domain of Ring1B, C-Ring1B, is a dimer in solution, with a dissociation constant of 200 mu M, as shown by NMR, ITC, and analytical gel filtration. Each monomer is stable at physiological conditions in a wide pH range (similar to 5 kcal mol(-1) at 298 K), with a well-formed core and a spherical shape. The dimer has a high content of alpha-helix and beta-sheet, as indicated by FTIR spectra, and it is formed by the mutual docking of the preformed folded monomers. Since the C-terminal region is important for interaction with other proteins of the PRC1, the dimerization and the presence of those well-structured monomers might be a form of regulation.