Collaborative Research: Ethylene-Forming Enzyme

胍是一种潜在的氮肥，乙烯已被提议作为一种潜在的替代燃料来源；因此，形成这些化合物的生物合成反应具有重要的商业意义，因为它们对农业和生物燃料工业具有潜在的好处。该奖项将资助密歇根州立大学的Robert Hausinger博士和Jian Hu博士以及密歇根理工学院的Christo Christov博士研究细菌和真菌中的乙烯形成酶(EFE)如何催化双重反应生成胍或乙烯。在EFE的典型反应中，二氧化碳从其他分子(2-氧代戊二酸，或2OG)中去除，同时加入氨基酸L-精氨酸，将其转化为胍。或者，EFE催化2OG转化为乙烯，释放出二氧化碳/重碳酸盐。对EFE催化机制的研究为博士后研究员、研究生和本科生提供专门的生化、结构和计算培训，包括女性和来自代表人数较少的少数群体的学生。将这些研究纳入大学科学节，通过关于乙烯作为生物燃料的潜在用途的推广计划，让家庭和终身学习者参与进来。本研究项目的首要目标是阐明区分EFE催化的两种不同反应的分子决定因素，并通过实验和计算研究相结合的方式建立酶的催化机制。这项工作还调查了为什么铁(II)和20G依赖的加氧酶的其他成员不能产生乙烯。为了了解EFE催化的两个反应的基础，研究人员正在使用动力学、结构和计算方法表征蛋白质的自然发生的类似物、重建的祖先和定点定向变体。利用这些信息和结构引导的蛋白质工程，研究人员正在创造EFE变种，优化用于生产生物燃料乙烯或植物肥料胍，同时消除浪费的L-精氨酸羟基化或2OG降解反应。此外，该团队正在使用生化、动力学、光谱和计算方法来阐明EFE的化学反应机理。这项工作扩展了关于其他重要的铁(II)和2OG依赖的加氧酶的结构/机械信息，这些加氧酶无法催化这些反应。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。

Guanidine is a potential nitrogen fertilizer and ethylene has been proposed as a potential alternative fuel source; thus, the biosynthetic reactions that form these compounds are commercially important as they have potential benefits for agriculture and the biofuels industries. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Drs. Robert Hausinger and Jian Hu at Michigan State University, and Dr. Christo Christov at Michigan Technological Institute to investigate how ethylene-forming enzyme (EFE) from bacteria and fungi catalyzes dual reactions to form guanidine or ethylene. In the typical reaction of EFE, a carbon dioxide is removed from other molecules (2-oxoglutarate, or 2OG), while being added to the amino acid, L-arginine, to transform it into guanidine. Alternatively, EFE catalyzes the transformation of 2OG into ethylene, with the release of carbon dioxide / bicarbonate. Research into the mechanisms of EFE catalysis provides specialized biochemical, structural, and computational training to postdoctoral fellows, and graduate and undergraduate students, including women and students from underrepresented minority groups. Incorporation of these studies into a university science festival engages families and lifelong learners through outreach programs about the potential use of ethylene as a biofuel.The overarching goals of this research project are to elucidate the molecular determinants that distinguish the two distinct reactions catalyzed by EFE and to establish the catalytic mechanisms of the enzyme by a combination of experimental and computational studies. This work also investigates why other members of the iron(II)- and 2OG-dependent oxygenases fail to produce ethylene. To understand the basis of the two EFE-catalyzed reactions, the researchers are characterizing naturally occurring analogs, a reconstructed ancestor, and site-directed variants of the protein by using kinetic, structural, and computational methods. Using this information along with structure-guided protein engineering, the researchers are creating EFE variants optimized for the production of either the biofuel ethylene or the plant fertilizer guanidine while eliminating wasteful L-Arginine hydroxylation or 2OG-degrading reactions. In addition, the team is using biochemical, kinetic, spectroscopic, and computational methods to elucidate the chemical reaction mechanism of EFE. This work extends the structural/mechanistic information available on other important iron(II)- and 2OG-dependent oxygenases that are unable to catalyze these reactions.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.