Heteropolymeric Semi-Autonomous Repeat Proteins: Coupling Energetics, Structure, and Function

蛋白质是一种大分子，在人体内扮演着许多关键角色。在这个研究项目中，将进行实验以了解蛋白质分子如何相互作用。蛋白质经常粘在一起或结合到同一类型或不同类型的其他蛋白质上，这些类型的相互作用对蛋白质的结构、功能和稳定性至关重要。虽然通过确定蛋白质复合体的结构来“看到”这些相互作用是相当容易的，但蛋白质不同部分结合的规则尚不清楚。在这里，已经确定了一系列蛋白质，其中结合的蛋白质亚单位都在单一的蛋白质链中，使得研究它们的相互作用变得非常容易。研究将利用这些“串联重复蛋白”的结构来了解蛋白质亚单位粘在一起的规则。这些规则将不仅揭示为什么串联重复序列会粘在一起，也会揭示为什么不同的蛋白质链会粘在一起。因此，这些规则将提供对复合体中蛋白质结构和功能的理解，从蛋白质链对一直到赋予细胞和组织形状和机械性能并允许细胞相互通信的非常大的蛋白质集合。这项研究将帮助本科生和研究生在实验室中和通过使用计算机模拟来培训尖端生物物理和生物化学的方法。这些研究将使用实验和计算方法。实验室将制备五种不同蛋白质的片段，并将用X射线衍射和磁共振光谱研究它们的结构。碎片的稳定性将使用荧光和圆二色光谱等光学技术来确定。计算机模拟也将被用来了解哪些类型的相互作用促进蛋白质亚单位之间的相互作用。这项研究项目的一个关键方面是，这里研究的蛋白质的重复结构可以用一种名为“伊辛”模型的模型来分析。这一模型允许精确测量蛋白质亚基之间相互作用的强度。从这项分析中学到的规则不仅适用于其他重复蛋白质，也适用于非重复蛋白质组件，它们使用与重复蛋白质相同类型的相互作用(包装、电荷相互作用和氢键)。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Proteins are large molecules that play many critical roles in the body. In this research project, experiments will be performed to learn how protein molecules interact with each other. Proteins often stick together or bind to other proteins of the same type, or of different types, and these types of interactions are critical to protein structure, function, and stability. Though it is fairly easy to "see" these interactions by determining structures of protein complexes, the rules by which the different parts of proteins bind are not known. Here, a series of proteins have been identified in which the protein subunits that bind are all in a single protein chain, making studies of their interactions quite simple to study. Studies will take advantage of the architecture of these "tandem repeat proteins" to learn the rules by which protein subunits stick together. These rules will reveal not only why tandem repeats stick together, but also why separate protein chains stick together. Thus these rules will provide an understanding of protein structure and function in complexes ranging from pairs of protein chains all the way up to the very large protein assemblies that give cells and tissues their shapes and mechanical properties and allow cells to communicate with each other. This research will help train students, both at the undergraduate and graduate level, in the methods of cutting-edge biophysics and biochemistry, both in the laboratory and through the use of computer simulations.These studies will use experimental and computational methods. Fragments of five different proteins will be prepared in the lab, and their structures will be studied with x-ray diffraction and magnetic resonance spectroscopy. Fragment stabilities will be determined using optical techniques like fluorescence and circular dichroism spectroscopy. Computer simulations will also be used to learn what types of interactions promote interaction between protein subunits. A key aspect of this research project is that the repeating structure of proteins studied here can be analyzed with a model called an "Ising" model. This model allows the precise measurement of the strength of interaction between protein subunits. The rules that are learned from this analysis will apply not only to other repeat proteins, but to non-repeating protein assemblies, which use the same types of interactions (packing, charge interactions, and hydrogen bonding) as repeat proteins do.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.