Collaborative Research: Interfacing Students at Three Universities to Elucidate Enzymatic Transformations of Guanide Compounds that Impact Health and the Environment

在化学系生命过程化学(CLP)项目的支持下，马奎特大学的Martin St.Maurice博士、明尼苏达双子城市大学的Lawrence Wackett博士和Hamline大学的Betsy Martinez-Vaz博士正在研究微生物用来降解化肥、燃料推进剂和药品中常见的双胍化合物的酶和代谢途径。最著名的例子是双胍类药物二甲双胍，它是世界上第四大处方药。二甲双胍正在以惊人的速度进入废水处理厂，对它是如何被微生物降解的没有明确的认识。通过对酶的结构/功能、化学生物学、比较基因组学和微生物学的详细研究，本项目旨在确定代谢途径(S)，并表征负责生物降解二甲双胍及其相关的胍和双胍化合物的细菌酶。该项目预计将提供有用的数据，以帮助科学家和工程师在市政水处理厂开发更好的生物修复实践，在那里二甲双胍是主要的进入化学品。此外，该项目通过将拟议的研究直接纳入研究生培训、多机构本科课程、职业指导和暑期实习，整合了三所大学的教学、指导和培训，大大扩大了该项目的影响。中心代谢动脉包括鸟脲水解酶、胍羧基酶、羧基胍脱亚胺酶和尿氨酸水解酶的联合活性。用X-射线结晶学和酶动力学分析表征了该酶对底物选择性的分子贡献。通过研究酶的催化机制、亚基的功能作用和底物通道的潜力，来研究羧基胍脱亚胺酶的结构和功能。负责细菌降解二甲双胍的途径和酶(S)将通过酶分离、纯化和比较基因组学相结合，跨潜在相关细菌物种进行鉴定，随后将详细描述二甲双胍降解酶(S)的结构和功能。该项目预计将提供有关双胍化合物如何进入生物降解途径的新信息，为更好地了解一类重要的富氮人造化合物是如何环境退化的提供了门户。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 (CLP) program in the Division of Chemistry, Drs. Martin St. Maurice from Marquette University, Lawrence Wackett from University of Minnesota-Twin Cities, and Betsy Martinez-Vaz from Hamline University are studying the enzymes and metabolic pathways that microbes use to degrade guanide and biguanide compounds that are commonly found in fertilizers, fuel propellants and pharmaceuticals. The most notable example is the biguanide drug metformin, which represents the fourth most prescribed pharmaceutical on the planet. Metformin is entering wastewater treatment plants at an alarming rate, with no clear sense of how it is being degraded by microorganisms. Using detailed studies of enzyme structure/function, chemical biology, comparative genomics and microbiology, this project aims to identify the metabolic pathway(s) and characterize the bacterial enzymes responsible for biodegrading metformin and related guanide and biguanide compounds. This project is expected to provide useful data to assist scientists and engineers in the development of better bioremediation practices in municipal water treatment plants where metformin is a major entering chemical. Further, this project integrates teaching, mentorship and training across three universities by incorporating the proposed research directly into graduate training, multi-institutional undergraduate courses, career mentorship and summer internships, significantly broadening the impact of the project.This project seeks to generate a comprehensive description of the metabolic pathways that are available naturally for the degradation of guanidinium compounds by microbial species and their relevant enzymes in wastewater and also in the human gut environment. The central metabolic artery includes the combined activities of guanylurea hydrolase, guanidine carboxylase, carboxyguanidine deiminase and allophanate hydrolase. The molecular contributions to the substrate selectivity of guanidine carboxylase will be characterized by x-ray crystallography and enzyme kinetic analysis. The structure and function of the carboxyguanidine deiminase enzyme will be examined by investigating the mechanism of catalysis, the functional role of the subunits and the potential for substrate channeling. The pathway and enzyme(s) responsible for bacterial metformin degradation will be identified by a combination of enzyme isolation, purification, and comparative genomics, across potentially relevant bacterial species, followed by detailed structural and functional characterization of the metformin-degrading enzyme(s). This project is expected to provide new information on how biguanide compounds are funneled into biodegradation pathways, providing a gateway to better understanding of how one important class of nitrogen-rich man-made compounds, produced across a variety of industrial sectors, is environmentally degraded.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.