Molecular Mechanisms of the Evolution of Steroid Receptor-Ligand Interactions

描述(申请人提供)：这个项目的目标是在分子水平上理解蛋白质的进化。将采取结合进化生物学和分子生物物理学优势的跨学科方法。随着蛋白质的进化，它们必须保持功能，否则就会被选择移除。最近使用祖先蛋白复活的研究发现，在医学上重要的类固醇受体(SR)蛋白的进化中存在功能中间体。连接不同功能状态的突变途径具有强烈的符号上位性：“允许性”突变必须先于“功能转换”突变，才能维持进化轨迹上的功能。这些允许性突变的机制还不是很清楚。这个项目将使用生物物理学和定向进化的方法来确定这些历史上允许的突变的机制。该项目的第一个目标是探索蛋白质稳定性和进化之间的关系。第二个目的是了解偶然性在复杂蛋白质功能进化中的作用。这项工作对理解蛋白质进化的一般原理具有重要意义。它还将提供对SRS中配体特异性的分子决定因素的洞察，这将为创造调节SR功能的新型治疗剂的尝试提供信息。 与公共健康相关：类固醇受体--从哮喘到癌症等疾病的关键参与者--必须区分类似的激素才能正常发挥作用。像所有蛋白质一样，它们执行这一功能的能力是它们进化史的产物。该项目试图了解这一功能是如何演变的，这将有可能允许新药调节类固醇受体功能来治疗疾病。

DESCRIPTION (provided by applicant): The goal of this project is to understand protein evolution at the molecular level. An interdisciplinary approach will be taken that combines the strengths of evolutionary biology and molecular biophysics. As proteins evolve, they must maintain function or they will be removed by selection. Recent investigations using ancestral protein resurrection have found functional intermediates in the evolution of the medically important steroid receptor (SR) proteins. The mutational pathway connecting different functional states is characterized by strong sign epistasis: "permissive" mutations must precede "function-switching" mutations to maintain function along the evolutionary trajectory. The mechanism of these permissive mutations is not well understood. This project will use the methods of biophysics and directed evolution to determine the mechanisms of these historical permissive mutations. The first aim of the project is to probe the relationship between protein stability and evolution. The second aim is to understand the role of contingency in the evolution of complex protein function. This work has important implications for understanding the general principles of protein evolution. It will also provide insight into the molecular determinants of ligand specificity in SRs, which will inform attempts to create novel therapeutic agents that modulate SR function. PUBLIC HEALTH RELEVANCE: Steroid receptors-which are key players in diseases ranging from asthma to cancer-must discriminate between similar hormones to function properly. Like all proteins, their ability to perform this function is a product of their evolutionary history. This project attempts to understand how this function evolved, which will potentially allow for new drugs to modulate steroid receptor function to treat disease.