Designing novel structures biomaterials and folding pathways of the TPR repeat proteins

蛋白质是所有生命系统的重要组成部分-经过数千年的进化，形成特定的造型，使它们能够执行从免疫反应和细胞信号到细胞骨架和肌肉收缩中的结构作用的各种功能。然而，为了实现它们的多种功能，每个蛋白质必须首先从非结构化的高度灵活的线性氨基酸链折叠成紧凑和特定的三维结构。此外，它是蛋白质的三维结构，结合其生物物理特性（如灵活性，热力学和稳定性），定义其生物功能。然而，尽管这些关系的基本性质，他们仍然知之甚少。虽然迄今为止研究的大多数蛋白质具有某些结构特征，将其归类为球状蛋白质，但这并不代表所有蛋白质。例如，在自然界中发现的20个最常见的蛋白质家族中，有5个属于重复蛋白质。它们拥有一种全新的三维结构。与被高度研究的球状折叠相反，球状折叠具有与其序列中的其他残基相互作用以将其结构锁定在适当位置的氨基酸，重复蛋白质形成氨基酸残基重复块与序列中接近的残基相互作用的结构。然后，重复的块堆叠在彼此的顶部，形成一个细长的结构，就像螺旋楼梯中的楼梯。此外，这种拉长的结构允许重复蛋白进化成分子支架，允许其他蛋白停靠在它们上面，从而控制和调节许多重要细胞过程的功能。因此，令人兴奋的重复蛋白质的结构特性，不仅提供了一个令人兴奋的系统，以验证一个新的蛋白质类的能量和结合特异性，但也提出了一个独特的机会，以解决当前的问题，在蛋白质折叠/错误折叠，设计和生产新的生物材料。因此，本研究计划将重点关注两个相互关联的领域，我们将研究某些具有代表性的重复序列蛋白质如何（i）设计以形成新的结构和生物材料，以及（ii）通过特定的折叠途径进行修饰以引起折叠。为了实现这些目标，我们将采用多学科的方法，结合分子生物学，蛋白质工程和生物物理特性。这项研究的意义和对社会的好处可以很容易地通过越来越多的疾病清单来理解，这些疾病的分子基础与突变有关，这些突变要么是展开蛋白质，错误折叠蛋白质，要么是阻止蛋白质相互作用。此外，通过了解氨基酸序列如何指定蛋白质结构，我们可以开始合理设计这些蛋白质的性质，以产生具有治疗价值的新型生物材料。这项工作将在蛋白质折叠，蛋白质设计和生物纳米技术领域的研究人员极大的兴趣。

Proteins are essential components in all living systems - evolving over many millennia into specific sculpted forms that enable them to perform a diverse range of functions from immune response and cell signaling to structural roles in the cytoskeleton and muscle contraction. However, to fulfil their multitude of functions, each protein must first fold from an unstructured highly flexible linear chain of amino acids to a compact and specific three-dimensional structure. Further, it is the three dimensional structure of a protein, combined with its biophysical characteristics (such as flexibility, thermodynamics and stability) that defines its biological function. Yet, despite the fundamental nature of these relationships, they are still poorly understood. While most proteins studied so far have certain structural features that class them as globular, this is not representative of all proteins. For example, of the twenty most common families of protein found in nature, five are of a class called repeat proteins. These possess a radically new type of three-dimensional structure. Contrary to the highly studied globular folds, which have amino acids that interact with other residues distant in their sequence to lock their structure in place, repeat proteins form structures where repeated blocks of amino acids residues interact with residues close in sequence. The repeated blocks then stack on top of each other to form an elongated structure, like stairs in a spiral staircase. Moreover, such elongated structures have allowed repeat proteins to evolve into molecular scaffolds that allow other proteins to dock onto them and thus control and regulate the function of many important cellular processes. Thus, the exciting structural properties of repeat proteins not only provide an exciting system to characterise the energetics and binding specificities of a novel class of protein, but also present a unique opportunity to address current issues in protein folding/misfolding, design and production of novel biomaterials. The research proposed in this grant will therefore focus on addressing two inter-related areas, we will investigate how certain representative repeat proteins can (i) be designed to form novel structures and biomaterials and (ii) be modified to cause folding through specific folding pathways. To accomplish these aims, we will employ a multidisciplinary approach that combines molecular biology, protein engineering and biophysical characterisation. The significance of this research and benefits to society can be easily appreciated by the growing list of diseases whose molecular basis are linked to mutations that either unfold protein, mis-fold protein or prevent proteins interacting with one another. Further, by learning how amino acid sequence specifies protein structure we can begin to rationally design the properties of these proteins to produce novel biomaterials of therapeutic value. This work will be of great interest researchers in the fields of protein folding, protein design and bionanotechnology.