Development of a Mechanism and Structure-Guided Methodology for De Novo Enzyme Design

项目摘要/摘要 自然而然，酶的特征是它们能够按以下顺序加速化学反应 与在水溶液中观察到的结果相比，具有更强的特异度。然而，这些催化作用 在人工合成的化学或生物系统中，这些特性还有待实现。虽然已经有很多 蛋白质从头设计的最新进展，实现了对单个原子和 酶催化所需的官能团仍然是一个长期存在的挑战，并依赖于定向 进化和高通量筛选，以改进设计。主动站点设计的基本原则 能够以与天然酶相似的速率和亲和力结合和催化底物 将代表着我们对结构-功能关系和蛋白质起源的理解上的突破 (DYS)函数。小分子结合蛋白从头设计的最新进展表明 能够定位非共价相互作用，例如从蛋白质到配体官能团的氢键， 精确度低于标准。基于这种方法，假设如果非共价相互作用可以 合理地设计结合，然后它们可以引导实现从头开始的酶设计通过 优先稳定TS，以实现快速反应速度。为了验证这一假说，能够 Kemp消除反应模型将使用自下而上的方法从头设计，以安装通用的 建立并调整其反应性，组装能够与底物和TS类似物结合的活性部位，并开发 优先TS稳定化的负设计策略。这些基本的见解将针对 第一个全新的金属β-内酰胺酶，一个研究抗生素耐药性和蛋白质进化的模型系统 对人类健康有影响。大的和高极性的β-内酰胺类抗生素的催化周转提供了 对我们设计非共价相互作用能力的敏感测试。这将通过扩大规模来实现， 利用生物信息学和功能导向设计的可设计蛋白质支架的不对称性和拓扑结构 多结构域蛋白质的策略，锌离子和底物结合位点的从头设计，以及De的发展 优先过渡态稳定化的新方法。拟议的调查将通过以下方式完成 计算和实验方法，从Silico方法开始基准折叠和 设计的蛋白质中反应中间产物的结合。然后，有希望的设计将被表达、纯化和 用等温量热法和光学方法表征了它们的结合亲和力和催化速率常数 分光镜。这些功能研究将通过使用X射线进行结构表征来补充 结晶学和核磁共振波谱，以确认设计方法的准确性。成功从头开始 功能性酶的设计将代表着我们对结构-功能的理解的突破 复杂蛋白质功能中非共价相互作用的关系和作用。

Project Summary/Abstract Naturally enzymes are characterized by their ability to accelerate chemical reactions by orders of magnitude and with far greater specificity than those observed in aqueous solution. However, these catalytic properties have yet to be realized in synthetic chemical or biological systems. While there have been many recent advances in the de novo design of proteins, achieving the exquisite control of individual atoms and functional groups necessary for enzyme catalysis remains a long-standing challenge and has relied on directed evolution and high-throughput screening to improve upon designs. The first principles design of an active site capable of substrate binding and catalysis with rates and affinities similar to those found in natural enzymes would represent a breakthrough in our understanding of structure-function relationships and the origins of protein (dys)function. A recent advance in the de novo design of small-molecule-binding proteins demonstrates the ability to position non-covalent interactions, such as hydrogen bonds from a protein to ligand functional groups, with sub-Å accuracy. Based on this methodology, it’s hypothesized that if non-covalent interactions can be rationally designed for binding, then they can be directed towards achieving de novo enzyme design through preferential TS-stabilization to achieve fast reaction rates. In order to test this hypothesis, enzymes capable of the model Kemp elimination reaction will be de novo designed using a bottom-up approach to install a general base and tune its reactivity, assemble an active site capable of substrate- and TS-analog-binding, and develop a negative design strategy for preferential TS-stabilization. These fundamental insights will be directed towards the first de novo metallo-β-lactamase, a model system for studying antibiotic resistance and protein evolution with human health implications. Catalytic turnover of the large and highly polar β-lactam antibiotics provides a sensitive test of our ability to design non-covalent interactions. This will be achieved by expanding upon the size, asymmetry, and topology of designable protein scaffolds using a bioinformatic and function-guided design strategy for multi-domain proteins, de novo design of a Zn2+- and substrate-binding site, and development of de novo methods for preferential transition-state stabilization. The proposed investigations will be achieved using both computational and experimental methods, starting from in silico approaches to benchmark the folding and binding of reaction intermediates in designed proteins. Promising designs will then be expressed, purified, and characterized in terms of their binding affinity and catalytic rate constants using isothermal calorimetry and optical spectroscopies. These functional studies will be complemented by structural characterization using X-ray crystallography and NMR spectroscopy to confirm the accuracy of the design methodology. Successful de novo design of functional enzymes would represent a breakthrough in our understanding of structure-function relationships and the role of non-covalent interaction in complex protein function.