CAREER: Enzymatic Sulfur Incorporation and Modification in the Biosynthesis of Natural Products

在化学系生命过程化学项目的支持下，南卡罗来纳大学的李杰正在研究大自然如何利用酶来结合和修饰微生物次生代谢物中的硫中心。这些天然产品为生产微生物提供了竞争优势，同时在医药、制造业和农业应用中也具有重要的基础价值。与被广泛研究的硫在初级代谢(如核苷酸和氨基酸)中的掺入相反，人们对硫在次生代谢物中的安装存在普遍理解上的差距。因此，这项研究试图从分子水平上理解这一生命过程，这不仅将为含硫天然产物提供宝贵的价值，还将为相关酶在实际应用中提供机会，包括合成生物学和绿色化学。此外，这项研究与教育和外联活动相配合，旨在向不同的学生群体，特别是代表不足的少数族裔社区的成员，包括南卡罗来纳州历史上的黑人学院和大学的学生，传达生命系统化学的重要性。一项重要的推广活动将涉及后院化学家计划，通过该计划，将在更大的社区中收集后院微生物样本，从而使社区成员参与发现新的天然产品。该研究项目旨在调查微生物天然产品生物合成中硫结合和修饰的酶学，最初的努力集中在两种独特的含硫天然产品：亚磺酸和磺脂。这项研究的目标包括了解硫中心是如何通过一系列酶反应步骤转移、结合和修饰在亚磺酸和/或磺脂中的，作为初级和次级代谢的一部分，以及来自有机和无机硫源。将研究一种黄素蛋白和两种依赖于磷酸吡哆醛的酶及其作用机制。将结合体内基因操作、体外酶重组、定点突变、酶动力学和蛋白质结晶学进行研究。考虑到硫反应活性的显著多样性，这项工作有望促进含硫天然产物的发现，并促进对天然产物生物合成中酶促硫掺入和修饰的基础了解。这项工作有可能产生新的策略，以释放天然产品化学中酶反应的力量。该奖项反映了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。

With the support of the Chemistry of Life Processes Program in the Chemistry Division, Jie Li from the University of South Carolina is studying how nature uses enzymes to incorporate and modify sulfur centers in microbial secondary metabolites. These natural products provide a competitive advantage to the producing microbes while also conferring significant fundamental value in medicinal, manufacturing, agricultural applications. In contrast to extensively studied sulfur incorporation in primary metabolism (e.g., nucleotides and amino acids), there is a gap in the general understanding of the installation of sulfur in secondary metabolites. Thus, this study seeks to develop a molecular-level understanding of this life process, which will provide not only valuable sulfur-containing natural products but also opportunities to employ relevant enzymes in practical applications, including synthetic biology and green chemistry. Furthermore, this research synergizes with education and outreach activities aimed at conveying the importance of the chemistry of living systems to diverse groups of students, particularly members of underrepresented minority communities including students at historically black colleges and universities in South Carolina. An important outreach activity will involve a Backyard Chemists program, through which backyard microbial samples will be collected in the larger community, thereby engaging community members in the discovery of new natural products.This research project is directed at the investigation of the enzymology of sulfur incorporation and modification in the biosynthesis of microbial natural products, with initial efforts focused on two unique types of sulfur-containing natural products: sulfenic acids and sulfonolipids. The goal of the research includes understanding how a sulfur center is transferred, incorporated, and modified in sulfenic acids and/or sulfonolipids through a series of enzymatic steps, as part of both primary and secondary metabolism and from both organic and inorganic sulfur sources. A flavoprotein and two pyridoxal phosphate-dependent enzymes and their mechanisms will be studied. A combination of in vivo genetic manipulation, in vitro enzymatic reconstitution, site-directed mutagenesis, enzyme kinetics, and protein crystallography will be employed. Considering the remarkable diversity of sulfur reactivity, this work is expected to both facilitate discovery of sulfur-containing natural products and advance fundamental understanding of enzymatic sulfur incorporation and modification in natural products biosynthesis. This work has the potential to yield new strategies to unleash the power of enzymatic reactions in natural products chemistry.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.