Biosynthesis of unusual bio-orthogonal functionalities in natural products

天然产物是研究、治疗甚至引起人类疾病的重要小分子，它们通常具有独特的官能团，这些官能团对其生物活性至关重要。通过开发合成这些官能团的生物合成机制，可以增强、改变或降低母体化合物的生物活性，并将生物合成机制应用于新系统中的官能团安装。为了实现这一目标，需要充分描述和理解天然产物生物合成背后的化学逻辑和酶机制。该项目将侧重于负责生物合成天然产物的特殊药效团的酶的功能表征和机制研究，包括末端炔烃、异腈和N-羟基三氮烯。独特的金属酶对它们的生物合成非常重要，包括膜结合的双铁依赖的双功能去饱和酶/乙烯酶，非血红素铁和α-酮戊二酸依赖的氧化酶/脱羧酶，用于异腈合成，以及一个由C-末端甲硫酰-tRNA合成酶样域和N-末端Cupin结构域组成的双域酶，用于N-羟基三氮烯的形成。对这些新发现的酶的生化和机理的了解仍然很差，有必要在这个项目中进行深入的研究。除了作为生物活性天然产物的弹头外，这些功能还具有独特的化学和物理性质，并被用于各种化学生物学应用的生物正交化学转化。因此，我们将进一步探索他们的生物合成机械的应用，按需在各种生物分子上安装这些“可点击”的功能。研究战略在选择新的功能及其独特但鲜为人知的生物合成机械、多学科研究工具以及直接针对与健康相关的应用的目标导向方法方面具有创新性。特别是，我们在方法设计中超越了酶和途径的表征，追求这些独特的酶在灵活性方面的应用，以对人类福祉产生积极影响。因此，拟议的研究具有重要意义，因为这既涉及天然产物酶学领域，也涉及基础和翻译层面的生物医学和生物技术研究的效用。

Natural products are important small molecules for studying, treating, and even causing human diseases, and they typically have unique functional groups that are critical for their biological activities. By exploiting the biosynthetic machinery by which these functionalities are synthesized, it is possible to enhance, vary or diminish the biological activities of parent compounds and apply the biosynthetic machinery to new systems for functional group installation. Toward this goal, the chemical logic and enzymatic machinery underlying natural product biosynthesis need to be fully characterized and understood. This project will focus on functional characterization and mechanistical interrogation of enzymes responsible for biosynthesis of unusual pharmacophores of natural products, including terminal alkyne, isonitrile and N-hydroxytriazene. Unique metalloenzymes have been identified important for their biosynthesis, including the membrane-bound di-iron dependent bifunctional desaturase/acetylenase for alkyne generation, the non-heme iron and α-ketoglutarate dependent oxidase/decarboxylase for isonitrile synthesis, and a didomain enzyme consisting of a C-terminal methionyl-tRNA synthetase-like domain and an N-terminal cupin domain for N-hydroxytriazene formation. The biochemical and mechanistic understanding of these newly discovered enzymes remain poor, warranting an in-depth study in this project. In addition to serving as the warheads of bioactive natural products, these functionalities have distinct chemical and physical properties and are utilized in bio-orthogonal chemical transformations for various chemical biology applications. We will thus further explore the application of their biosynthetic machinery to install these “clickable” functionalities on various biomolecules on demand. The research strategy is innovative in terms of the choice of novel functionalities and their unique but poorly understood biosynthetic machinery, the multidisciplinary research tools, and the goal-oriented approaches to directly target health-related applications. In particular, we go beyond the enzyme and pathway characterization in the approach design, pursuing applications of these unique enzymes in terms of flexibility to have a positive impact on human well-being. The proposed research is thus significant due to both implications for the field of natural product enzymology and utilities in biomedical and biotechnological research at the basic and translational levels.