Structural investigation of an immunoglobulin domain: biosynthesis on the ribosome and co-translational folding

免疫球蛋白结构域的结构研究：核糖体的生物合成和共翻译折叠

• 批准号: 2075757
• 金额: --
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2075757
• 关键词: Structural; investigation; immunoglobulin; domain; biosynthesis

Protein folding is the process by which a polypeptide acquires its correct threedimensional, biologically active function. During biosynthesis on the ribosome the elongating nascent chain emerges in a vectorial manner from the restrictedenvironment of the ribosomal exit tunnel and begins to explore conformational space. The structural understanding of the emerging nascent chain is sparse because its inherent dynamics is making it invisible to conventional structural and biophysical methods, including conventional NMR. Application of paramagnetic relaxation enhancement (PRE) NMR cannot only aid in structural characterization of the major populated state but can also aid in detecting and characterizing fast relaxing minor states which are inherent to co-translational folding.The PRE method probes ensemble-averaged, transient contacts over distances as great as 15-24 Å. As previously described for isolated proteins, a nitroxide spin-label is attached to a region of a protein, and in its oxidized (paramagnetic) state, enhances relaxation of heteronuclear coherences. Relaxation enhancement scales as r-6 with label proximity, allowing the computation of distance restraints used to calculate ensembles of structures by MD simulations.Using this approach, I will structurally investigate the inherently dynamic process of cotranslational folding using an immunoglobulin domain as my model protein and get a deeper understanding of this so far structurally invisible process.

蛋白质折叠是多肽获得其正确的三维生物活性功能的过程。在核糖体上的生物合成过程中，伸长的新生链以矢量方式从核糖体出口通道的限制性扩张中出现，并开始探索构象空间。对新兴新生链的结构理解是稀疏的，因为其固有的动力学使其对常规结构和生物物理方法（包括常规NMR）不可见。顺磁弛豫增强（PRE）NMR的应用不仅有助于主要布居态的结构表征，而且还有助于检测和表征共同平移折叠所固有的快速弛豫次要态。PRE方法探测了15-24 μ m距离内的整体平均瞬时接触。如前所述的分离的蛋白质，氮氧化物自旋标记物连接到蛋白质的一个区域，并在其氧化（顺磁性）状态，增强松弛的heterogeneous凝聚力。松弛增强尺度r-6与标签的接近，允许计算距离的限制，用于计算合奏的结构通过MD simulation.Using这种方法，我将在结构上研究固有的动态过程中的共翻译折叠使用免疫球蛋白结构域作为我的模型蛋白质，并得到更深入的了解这个迄今结构上看不见的过程。