NMR Studies or I-kappa B alpha and its interaction with NF-kappa B

NMR 研究或 I-kappa B α 及其与 NF-kappa B 的相互作用

• 批准号: 7676681
• 负责人: CARLA F CERVANTES
• 金额: $ 2.12万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7676681
• 关键词: Amides; Ankyrin Repeat; Arthritis; Asthma; Binding; Circular Dichroism; Complex; Consensus Sequence; Crystallography; Diabetes Mellitus; Disease; Event; Health; Human; Hydrogen; I Kappa B-Alpha; Label; Malignant Neoplasms; Measurement; Modeling; Mutation; NF-kappa B; Normal Cell; Process; Protein Dynamics; Proteins; Regulation; Relaxation; Roentgen Rays; Sampling; Signal Pathway; Solutions; Solvents; Structure; Vertebral column; Virus Diseases; base; cell growth; in vivo; inhibitor/antagonist; mutant; research study; transcription factor

DESCRIPTION (provided by applicant): Project Summary The regulation of the transcription factor Nuclear Factor Kappa B (NF-kB) by its inhibitor, IkBa, is critical for normal cell growth and misregulation is associated with many diseases. The structure of the complex has been elucidated by x-ray crystallography (Huxford et al. 1998; Jacobs and Harrison 1998) and the interface between the two proteins is comprised of interactions between all six beta hairpin loops of IkBalpha. Attempts to crystallize free IkBa were unsuccessful and amide hydrogen exchange experiments revealed that nearly all of the first, fifth and sixth ankyrin repeats exchanged within a few minutes suggesting they were somehow unstructured (Cray Hughes et al. 2004). The fifth and sixth beta-hairpins show a marked decrease in solvent accessibility upon binding to NF-kB that can not be explained simply from protection at the interface. At first, we interpreted these results as indicating that IkBa folds upon binding, but circular dichroism experiments showed no increase in secondary structure when IkBalpha bound to NF-kB (Croy Hughes et al. 2004). Taken together the results suggest that free IkBalpha is somehow dynamic and perhaps molten globular and that it folds upon binding but the folding is more a decrease in the ensemble of states rather than formation of new secondary structure. The best way to probe such an event is by backbone dynamics experiments. The Specific Aims are: AIM 1: Resonance Assignments of Free IkBa. Uniformly 13C, 15N double-labeled protein and deuterated samples as well as selective labeling will be used. Progress on the assignments has been made based primarily on the TROSY-HNCA and HSQC-NOESY-HSQC spectra of 0.2 mM wild type IkBa, and we now have several stabilized mutants that will be assigned simultaneously. AIM 2: Elucidation of the Dynamics of IkBa in Solution. Standard R1, R2 and heteronuclear NOE experiments as well as rcCPMG experiments will be used. AIM 3: Elucidation of the backbone dynamics of Stabilized Mutants of IkBa. Mutations that restore the consensus sequence for stable ankyrin repeat proteins increase stability by 5 kcal/mol over wild type. The results from these experiments will show how dynamics relates to stability in ankyrin repeat proteins. AIM 4. Compare the backbone dynamics of free and NF-kB-bound IkBa. Relevance to human health This project will help understand the regulation of the NF-kB signaling pathway that is critical for human health and is misregulated in diseases such as cancer, arthritis, asthma, diabetes, AIDs and viral infections.

描述(由申请人提供)：项目摘要转录因子核因子-kB(核因子-kB)被其抑制物IkBA调节，对正常细胞生长至关重要，而调节不当与许多疾病有关。该络合物的结构已通过X射线结晶学(Huxford et al.1998；雅各布斯和哈里森1998)，两种蛋白质之间的界面由IkBalpha的所有六个β发夹环之间的相互作用组成。尝试结晶游离的IkBA没有成功，酰胺氢交换实验表明，几乎所有的第一、第五和第六个锚蛋白重复序列在几分钟内交换，这表明它们不知何故是无结构的(Cray Hughes等人)。2004年)。第五和第六个β-发夹显示，当与核因子-kB结合时，溶剂可及性显著下降，这不能简单地从界面保护来解释。首先，我们将这些结果解释为表明IkBA在结合时折叠，但圆二色实验表明，当IkBalpha与NF-kB结合时，二级结构没有增加(Croy Hughes等人。2004年)。综上所述，结果表明，自由的IkBalpha在某种程度上是动态的，可能是熔融的球状的，它在结合时折叠，但折叠更多的是态集合的减少，而不是新的二级结构的形成。探索这种现象的最好方法是通过骨干动力学实验。具体目标是：目标1：自由Ikba的共振赋值。将使用统一的13C，15N双标记蛋白质和氚样品以及选择性标记。主要基于0.2 mM野生型Ikba的TROSY-HNCA和HSQC-NOESY-HSQC谱，在指认方面取得了进展，我们现在有几个稳定的突变体将同时指认。目的2：阐明IkBA在溶液中的动力学。将使用标准的R1、R2和异核NOE实验以及rcCPMG实验。目的3：阐明Ikba稳定突变体的骨架动力学。恢复稳定的锚蛋白重复蛋白共同序列的突变使稳定性比野生型增加了5千卡/摩尔。这些实验的结果将显示动态如何与锚定蛋白重复蛋白的稳定性有关。目的4.比较游离和核因子-kB结合的IkBA的骨架动力学。与人类健康的相关性该项目将有助于了解对人类健康至关重要的核因子-kB信号通路的调控，该信号通路在癌症、关节炎、哮喘、糖尿病、艾滋病和病毒感染等疾病中被错误调控。