Structural and functional studies of the IkappaB kinase (IKK) complex

摘要 核因子B(NF-B)家族的转录因子是进化上保守的主因子 免疫和炎症反应的调节者。它们被激活是为了响应结扎 许多受体包括T细胞受体、B细胞受体、肿瘤坏死分子 肿瘤坏死因子受体超家族与Toll样受体/白介素1受体 超级大家庭。 I？B激酶(IKK)是核因子-B活化的核心，由IKK和IKK组成。 介导两条核因子-B活化途径。典型的核因子-B途径是由 微生物和病毒感染和促炎细胞因子，并依赖IKK？ 磷酸化和激活。另一种途径是由 TNF细胞因子家族，并选择性激活IKK。活化的IKK磷酸化I？B，先导 它们的多泛素化和蛋白酶体随后的降解有关。被释放的核因子-B 二聚体转位到细胞核以调节转录。因为它在核因子-B中的重要性 激活，IKK，特别是IKK？已经成为许多人类潜在的治疗靶点 疾病。 调节蛋白Nemo(也称为ikk？或FIP-3)与ikk和/或ikk？to相互作用 形成IKK？、IKK？或IKK/？全息复合体。完整的IKK？全息复合体大约是 分子质量为700-900kD，含有IKK和NEMO的多个拷贝。IKK？和IKK？ 两者都包含以下保守的可识别结构域：一个激活域(KD)，一个亮氨酸 拉链结构域(LZ)、螺旋环螺旋结构域(HLH)和C-末端Nemo结合结构域 (NBD)。NEMO包含一个N末端的激酶结合结构域(KBD)，这是一种最低限度的齐聚 结构域(MOD)，也是泛素结合结构域(UBD)和C端锌指 域(ZF)。 IKK和NF-B信号转导引起了人们的极大关注，发表了30,000多篇论文 发表了关于这一主题的文章。尽管生物学上很重要，但没有一个成功的结构 据报道，已经在IKK上做出了决定，这表明了项目的难度。至 为了阐明ikk功能的分子基础并帮助发现ikk抑制剂，我们 提出了一系列IKK的结构和功能研究，特别是IKK？及其调控 蛋白质尼莫。

ABSTRACT Transcription factors in the nuclear factor ¿B (NF-¿B) family are evolutionarily conserved master regulators of immune and inflammatory responses. They are activated in response to ligation of many receptors including T-cell receptors, B-cell receptors, members of the tumor necrosis factor (TNF) receptor superfamily and the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) superfamily. The I¿B kinase (IKK), comprising IKK¿ and IKK¿, is at the heart of NF-¿B activation and mediates two NF-¿B activation pathways. The canonical NF-¿B pathway is triggered by microbial and viral infections and pro-inflammatory cytokines and is dependent on IKK¿ phosphorylation and activation. The alternative pathway is triggered by certain members of the TNF cytokine family and selectively activates IKK¿. Activated IKK phosphorylates I¿Bs, leading to their polyubiquitination and subsequent degradation by the proteasome. The freed NF-¿B dimers translocate to the nucleus to mediate transcription. Because of its importance in NF-¿B activation, IKK, especially IKK¿, has become a potential therapeutic target for many human diseases. The regulatory protein NEMO (also known as IKK¿ or FIP-3) interacts with IKK¿ and/or IKK¿ to form the IKK¿, IKK¿ or IKK¿/¿ holo-complex. The intact IKK¿ holo-complex is approximately 700-900kD in molecular mass containing multiple copies of IKK¿ and NEMO. IKK¿ and IKK¿ both contain the following conserved recognizable domains: a kinase domain (KD), a leucine zipper domain (LZ), a helix loop helix domain (HLH) and a C-terminal NEMO-binding domain (NBD). NEMO contains an N-terminal kinase-binding domain (KBD), a minimal oligomerization domain (MOD) that is also the ubiquitin binding domain (UBD) and a C-terminal zinc finger domain (ZF). IKK and NF-¿B signaling has attracted tremendous attention with more than 30,000 papers published on the subject. Despite the biological importance, not a single successful structure determination has been reported on IKK, an indication on the difficulty of the project. To elucidate the molecular basis of IKK function and to assist the discovery of IKK inhibitors, we propose a series of structural and functional studies on IKK, in particular, IKK¿ and its regulatory protein NEMO.