STRUCTURE AND STABILITY OF IKB/NF-KB COMPLEXES

IKB/NF-KB 复合物的结构和稳定性

• 批准号: 7585240
• 负责人: GOURISANKAR GHOSH
• 金额: $ 26.17万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7585240
• 关键词: 26S proteasome; Ankyrin Repeat; Binding; Biochemical; Biochemistry; Biological; Biological Process; Cells; Class; Complex; Disease; Event; Family member; Gene Expression Regulation; Genes; Half-Life; Human; I Kappa B-Alpha; IkappaB kinase; In Vitro; Interphase Cell; Knock-out; Life Cycle Stages; Light; Mediating; Mus; NF-kappa B; Numbers; Play; Proteins; Regulation; Role; Signal Transduction; Specificity; Stimulus; Structure; TNFRSF5 gene; Testing; Thermodynamics; Ubiquitination; X-Ray Crystallography; base; dimer; in vivo; inhibitor/antagonist; insight; mRNA Differential Displays; member; multicatalytic endopeptidase complex; p65; protein folding; research study; transcription factor

Human NF-kappaB (NF-KB) transcription factors regulate the expression of large number of genes involved in diverse biological activities. A sub-class of IKB proteins, known as prototypical IKB (IKBalpha, IKBbeta and iKBepsilon), inhibits NF-KB transcriptional activity by forming stable complexes with NF-KB dimers. These inhibited complexes define a paradigm of cell signaling where signal induced NF-KB activation is regulated by the degradation of IKB. The prototypical IKB proteins undergo rapid turnover in resting cell when present in the free state, compared to when present as complexes with NF-KB. Recent observations indicate that the prototypical IKBs are partly unfolded, which may stabilize upon binding NF-KB. Interestingly, critical segments of NF-KB that are involved in binding IKB are also unfolded in their free states. We hypothesize that stability of IKB proteins regulates their turn over, NF-KB recognition and the lifetime of IKB/NF-KB complexes in quiescent cells. A separate class of IKB proteins, represented by Bcl3 and IKBzeta, carry out different functions. It is likely that functional differences between these two classes of 1KB proteins may correlate with their differential stability. The focus of this proposal is to understand the mechanism of proteasome-mediated degradation of IKB and how their stability relates to their degradation. We have observed structural differences between prototypical IKB proteins such as the presence of a disordered insert in IKBbeta. We will test if IKBalpha and IKBbeta display differential specificity towards specific NF-KB dimers, and how structural differences between IKBalpha and IKBbeta play a role in such specificity-defining mechanisms. Finally, we will elucidate new structures of IKB/NF-KB complexes, which may provide insights into their biological functions. We will use X-ray crystallography, biochemistry and cell-based experiments to test our hypotheses.

人NF-kappab（NF-KB）转录因子调节大量基因的表达 在各种生物学活动中。 IKB蛋白的子类，被称为原型IKB（Ikbalpha，Ikbbeta和 ikbepsilon），通过与NF-KB二聚体形成稳定的复合物来抑制NF-KB转录活性。这些 抑制的复合物定义了一个细胞信号传导范式，其中信号诱导的NF-KB激活受调节 通过IKB的退化。当存在时，原型IKB蛋白会在静息细胞中快速转移 在自由状态下，与NF-KB的复合物相比。最近的观察表明 原型IKB部分展开，在结合NF-KB时可能会稳定。有趣的是，至关重要 在自由状态下也展开了涉及约束IKB的NF-KB段。我们假设 IKB蛋白的这种稳定性调节其转移，NF-KB识别和IKB/NF-KB的寿命 静态细胞中的复合物。由Bcl3和Ikbzeta代表的单独类别的IKB蛋白 不同的功能。这两类1KB蛋白之间的功能差异很可能可能 与它们的差异稳定性相关。该提议的重点是了解 蛋白酶体介导的IKB降解及其稳定性与它们的降解之​​间的关系。我们有 观察到的原型IKB蛋白之间的结构差异，例如存在无序插入物 在ikbbeta。我们将测试ikbalpha和ikbbeta是否对特定的NF-KB二聚体显示出不同的特异性，并且 Ikbalpha和Ikbbeta之间的结构差异如何在这种特异性定义机制中发挥作用。 最后，我们将阐明IKB/NF-KB综合体的新结构，这可能会为其提供见解 生物功能。我们将使用X射线晶体学，生物化学和基于细胞的实验来测试我们的 假设。