Structure and Function of Nifl1-2, A Novel Inhibitor of Nitrogenase Activity in th Earchaeon Methanococcus Maripaludis

生物固氮是一种广泛的代谢过程，通过某些微生物的生物活性将大气中的氮转化为肥料。该项目是对新发现的许多生物调节固氮酶活性的机制的后续研究，固氮酶是一种催化生化反应从而导致固氮的酶。这一机制涉及一种名为PII蛋白的蛋白质家族，它调节各种生物体的氮代谢功能。这项研究中要研究的特定蛋白质是NifI蛋白，它构成了一个以前未描述的PII蛋白亚家族。NifI的新特征及其对固氮酶活性的调节包括NifI与固氮酶的钼铁蛋白形成直接络合物，以及与其自身络合的NifI形成新的高级结构。这项研究将涉及使用模式微生物物种甲烷球菌进行生化、遗传和蛋白质结构的研究，甲烷球菌是系统发育领域的一个成员。这项研究的更广泛影响是环境、农业和教育。生物固氮有助于微生物及其相关植物的营养，而不会对环境产生与化肥相关的不利影响。这项工作还将对微生物学和生物化学领域的人员进行培训，包括将蛋白质结构与固氮生物学相结合。最后，这项工作为研究人员的教学和推广工作提供了支持，其中包括以微生物新陈代谢为主题的课程，参加华盛顿大学天体生物学的跨学科研究生项目，以及参加名为天体生物项目的K-12推广项目。

Biological nitrogen fixation is a widespread metabolic process that converts atmospheric nitrogen into fertilizer through the biological activity of certain microorganisms. This project follows up on a newly discovered mechanism by which many organisms regulate the activity of nitrogenase, the enzyme that catalyses the biochemical reactions that result in nitrogen fixation. The mechanism involves a family of proteins called PII proteins that regulates nitrogen metabolic functions in a variety of organisms. The particular proteins to be studied in this research are the NifI proteins, which constitute a previously uncharacterized subfamily of PII proteins. Novel features of NifI and its regulation of nitrogenase activity include the formation a direct complex between NifI and the molybdenum-iron protein of nitrogenase, and formation of novel higher order structures of NifI complexed with itself. The research will involve biochemical, genetic, and protein structural studies using the model microbial species Methanococcus maripaludis, a member of the phylogenetic domain Archaea.The broader impacts of the research are environmental, agricultural, and educational. Biological nitrogen fixation contributes to the nutrition of microorganisms and the plants with which they associate, without the adverse environmental effects associated with chemical fertilizers. The work will also result in the training of personnel in the areas of microbiology and biochemistry, including the integration of protein structure with the biology of nitrogen fixation. Finally, the work feeds into the investigator's teaching and outreach efforts, which include courses featuring microbial metabolism, participation in the University of Washington's interdisciplinary graduate program in Astrobiology, and participation in a K-12 outreach program called project Astrobio.