Biosyntheses of FeMo-co and FeV-co of Nitrogenase

固氮酶将N2转化为铵，铵是一种更容易获得的N形式。 人类营养在活性位点由raj编码，钼固氮酶是铁钼结合酶 vn 1编码的固氮酶含有结构相似的铁-钒辅因子， 该项目的总体目标是确定FeMo-co和FeV-co的生物合成途径。 co在固氮原核生物棕色固氮菌中的作用。nifBUSV基因产物是 合成两种辅因子。此外，合成需要nifNE、nifH和nifX产物 当细胞在V代替Mo上生长时，细胞合成vnfNE、vnfH和vnfX基因 本项目的具体目标是确定这些基因的作用， 在FeMo-co/FeV-co的合成过程中， 在每个辅因子的合成过程中。NifB的代谢产物NifB-co是FeMo的Fe和S供体。 Co和FeV-Co; NifB-Co结构的确定是本项目的目标。几种蛋白质在 FeMo-co合成途径包括NifH从55 Fe-NifB-co或从“MoO 42-”积累标记， FeMo-Co、55 Fe和11 Mo的体外合成将用于遵循该途径中的步骤。 同样，在FeV-co合成过程中，49 V在几种蛋白质上积累，55 Fe和49 V将用于 遵循FeV-co途径的步骤。VnfX最近被鉴定为一种积累V VnfX在FeV-co合成中的作用研究将是一个新的研究方向。 项目的主要目标。所有的生物都需要微量元素，在这个项目中获得的信息 这将增加我们对活细胞同化、积累和 区分用于构建许多氧化还原所需的复杂辅因子的微量元素 对细胞至关重要的反应。人体健康依赖于微量元素的适当代谢和利用 例如，本研究中正在研究的那些因素。

Nitrogenases carry out the conversion of N2 to ammonium, a form of N that is more readily available for human nutrition. At the active site of raj-encoded, molybdenum nitrogenase is the iron-molybdenum cofactor, FeMo-co. The vn/-encoded nitrogenase contains the structurally similar iron-vanadium cofactor, FeV-co. The overall goal of this project is to determine the pathways of biosynthesis of FeMo-co and FeV- co in the nitrogen-fixing procaryote, Azotobacter vinelandii. The nifBUSV gene products are required for synthesis of both cofactors. In addition, the nifNE, nifH and nifX products are required for the synthesis of FeMo-co. When cells are grown on V in place of Mo, the cell synthesizes vnfNE, vnfH and vnfX gene products for the synthesis of FeV-co. The specific goals of this project are to define the roles of these gene products in the syntheses of FeMo-co/FeV-co and to establish the basis for the specificity for Mo or V during synthesis of each cofactor. NifB-co, the metabolic product of NifB,is an Fe and S donor to FeMo- co and FeV-co; the determination of the structure of NifB-co is a goal of this project. Several proteins in the FeMo-co synthesis pathway including NifH accumulate label from 55Fe-NifB-co or from "MoO42- during the in vitro synthesis of FeMo-co, and55Fe and "Mo will be used to follow the steps in the pathway. Likewise, 49V accumulates on several proteins during FeV-co synthesis, and55Fe and49V will be used to follow the steps of the FeV-co pathway. VnfX has recently been identified as a protein that accumulates V and Fe during FeV-co synthesis, and the investigation of the role of VnfX in FeV-co synthesis will be a major goal of the project. All organisms require trace elements, and the information gained in this project will increase our understanding of the mechanisms by which living cells assimilate, accumulate, and discriminate between trace elements that are used to build complex cofactors required for many redox reactions crucial to the cell. Human health is dependent on proper metabolism and utilization of trace elements such as those being investigated in this study.