COBRE: UID: PROJ 3: EVOLUTION OF PROTEIN FLEXIBILITY

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。该项目的主要目标是通过发展更全面的快速相互转换的结构集合，了解控制动态、灵活蛋白质自然选择的进化约束和模式。为了实现这一目标，我们选择了一个基于复制蛋白a (RPA70) 70 KDa亚基的保守柔性连接体的模型系统。我们正在使用这个模型系统来确定自然选择是否以及如何保护动态的、灵活的蛋白质和蛋白质结构域的结构和功能。我们研究了四个RPA70同源物的瞬时二级结构和动力学，并观察到在整个进化过程中保持了高度动态的特性。人类RPA70同源物的较大片段揭示了连接体末端和侧翼折叠结构域之间明显的相互作用。我们目前正在调查这是否是一个普遍的特征。我们还研究了30多个RPA70同源物的序列保守性，并假设连接物是通过插入和删除事件以及重复扩展而进化的。最后，贝叶斯分类器正在开发，以识别基于化学性质的动态，灵活的蛋白质结构。虽然动态柔性蛋白和蛋白结构域在自然界中的存在和重要性已经得到了很好的确立，但这一提议标志着对其进化约束和模式的第一次系统实证研究。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The main goal of this project is to understand the evolutionary constraints and patterns that govern the natural selection of dynamic, flexible proteins by developing a more comprehensive picture of their rapidly interconverting structural ensembles. To accomplish this goal, we have selected a model system based on a conserved flexible linker from the 70 KDa subunit of replication protein A (RPA70). We are using this model system to determine if and how natural selection works to preserve the structure and function of dynamic, flexible proteins and protein domains. We have investigated the transient secondary structure and dynamics of the linkers from four RPA70 homologues and have observed the maintenance of a highly dynamic character throughout the course of evolution. Larger fragments of the human RPA70 homologue have revealed distinct interactions between the ends of the linker and the flanking folded domains. We are currently investigating the whether or not this is a general feature. We have also investigated the sequence conservation of more than 30 RPA70 homologues and hypothesize the linkers are evolving by insertion and deletion events as well as repeat expansion. Finally, Bayesian classifiers are being developed to identify dynamic, flexible protein structures based on chemical properties. While the presence and importance of dynamic flexible proteins and protein domains in nature is well established, this proposal marks the first systematic empirical investigation into their evolutionary constraints and patterns.