Menaquinone biosynthesis via the futalosine pathway

在人类和其他哺乳动物中，甲基萘醌是一种必需的维生素（维生素K），参与血液凝固和骨骼形成。缺乏维生素K会导致凝血时间延长和出血。有了这个奖项，化学部门的生命过程化学项目资助了德克萨斯农工大学（TAMU）的Tadhg Begley博士研究维生素K是如何生化合成的。该反应将随着时间的推移进行跟踪，以确定参与生物合成途径的两种酶的独特化学机制。由此产生的基础科学知识可能有助于设计和发现针对几种人类病原体的新抗生素。除了科学目标之外，Begley博士还将通过指导Prairie View A&amp；M大学的一名学生和教师来帮助增加来自不同背景的学生的参与。贝格利博士还为本科生提供研究机会，并通过一年一度的德州农工大学化学开放日与社区互动。研究的重点是氨基氟塔苷合成酶（MqnE）的完整机制表征。这种酶是不寻常的，它将腺苷自由基结合到反应产物中，而不是用它来提取氢原子。研究用电子顺磁共振确定了束缚的俘获性自由基的构象和自由基中间体的俘获。MqnE的机制是自由基s -腺苷-l-蛋氨酸（SAM）酶的模型系统，它通过自由基加成而不是通过氢原子提取来产生底物自由基。MqnC催化螺环化反应，也是一种自由基SAM酶。MqnD催化甲基萘醌的二氢萘醌部分的形成。反应产物的表征区分了该反应的两种机制。本研究将描述通过futalosine依赖途径生物合成甲基萘醌所需的所有酶，并将开发新的，通常有用的策略来研究酶介导的苯环自由基添加。更广泛的影响包括对Prairie View A&amp；M大学学生和教职员工的指导，为TAMU化学开放日开发一套生物实验，每年培训两名本科生进行生物化学研究，以及组织生物辅助因子国际会议。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In humans and other mammals, menaquinone is an essential vitamin (vitamin K) involved in blood clotting and bone formation. Vitamin K deficiency leads to prolonged blood clotting times and hemorrhaging. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Tadhg Begley from Texas A&M University (TAMU) to study how vitamin K is biochemically synthesized. The reaction will be tracked over time in order to determine the unique chemical mechanisms of two enzymes involved in the biosynthetic pathway. The resulting basic scientific knowledge may help in the design and discovery of new antibiotics targeting several human pathogens. In addition to the scientific goals, Dr. Begley will help to increase the participation of students from diverse backgrounds by mentoring a student and faculty member at Prairie View A&M University. Dr. Begley also provides research opportunities to undergraduates and engages with the community through the annual Texas A&M University Chemistry open house. The research studies focus on the complete mechanistic characterization of aminofutalosine synthase (MqnE). This enzyme is unusual in incorporating an adenosyl radical into the reaction product rather than using it to abstract a hydrogen atom. The studies determine the conformation of the bound captodative radical by Electron Paramagnetic Resonance and the trapping of radical intermediates. The mechanism of MqnE serves as a model system for radical S-adenosyl-l-methionine (SAM) enzymes that generate a substrate radical by radical addition rather than by hydrogen atom abstraction. MqnC catalyzes a spirocyclization reaction and is also a radical SAM enzyme. MqnD catalyzes the formation of the dihydro-napthoquinone moiety of menaquinone. Reaction product characterization differentiates the two proposed mechanisms for this reaction. This research will characterize all of the enzymes required for the biosynthesis of menaquinone via the futalosine-dependent pathway, and will develop of new, generally useful, strategies for studying enzyme-mediated radical additions to benzene rings. The broader impacts include the mentoring of students and faculty members at Prairie View A&M University, the development of a set of biological experiments for the TAMU Chemistry open house, the training of two undergraduates/year in biological chemistry research, and the organization of the international conference on biological cofactors.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.