As part of the efforts to understand nuclear IκB function in NF-κB-dependent gene expression, we report an X-ray crystal structure of the IκBζ ankyrin repeat domain in complex with the dimerization domain of the NF-κB p50 homodimer. IκBζ possesses an N-terminal α helix that conveys domain folding stability. Affinity and specificity of the complex depend on a small portion of p50 at the nuclear localization signal. The model suggests that only one p50 subunit supports binding with IκBζ, and biochemical experiments confirm that IκBζ associates with DNA-bound NF-κB p50:RelA heterodimers. Comparisons of IκBζ:p50 and p50:κB DNA complex crystallographic models indicate that structural rearrangement is necessary for ternary complex formation of IκBζ and p50 with DNA.

中文翻译：

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核 IκBζ 蛋白与 NF-κB p50 同型二聚体复合物的结构和生化分析


作为了解 NF-κB 依赖性基因表达中核 IκB 功能的努力的一部分，我们报道了 IκBζ 锚蛋白重复结构域的 X 射线晶体结构与 NF-κB p50 同型二聚体的二聚化结构域复合。IκBζ 具有一个 N 末端α螺旋，可传递结构域折叠稳定性。复合物的亲和力和特异性取决于核定位信号处的一小部分 p50。该模型表明只有一个 p50 亚基支持与 IκBζ 结合，生化实验证实 IκBζ 与 DNA 结合的 NF-κB p50：RelA 异二聚体结合。IκBζ：p50 和 p50：κB DNA 复合物晶体模型的比较表明，结构重排对于 IκBζ 和 p50 与 DNA 形成三元复合物是必需的。