Biosyntheses of FeMo-co and FeV-co of Nitrogenase

固氮酶将氮气转化为氮的一种形式的铵。 这是更容易获得的人类营养。在活动站点 在NIF编码的钼固氮酶中，钼固氮酶是铁钼辅因子， FEMO公司。VNF编码的固氮酶含有结构相似的 铁-钒共因子，FeV-co.这个项目的总体目标是 确定FeMo-CO和FeV-CO的生物合成途径 固氮原核生物，棕色固氮细菌。NifBUSV基因 这两种辅因子的合成都需要产物。此外， 合成FeMo-CO需要nifNE、nifH和nifX产物。 当细胞生长在V而不是Mo上时，细胞合成vnfNE， VnfH和vnfX基因产物用于合成FeV-co。具体的 该项目的目标是确定这些基因产物在 合成了FeMo-Co/FeV-Co，并为合成FeO-Co/FeV-Co 在每个辅因子的合成过程中，对钼或钒的特异性。NifB-co，The 代谢产物NifB是铁和S对FeMo-CO和FeV-CO的供体； 确定NifB-co的结构是本项目的一个目标。 FEMO-co合成途径中的几种蛋白质，包括nifH 体外累积~(55)Fe-NifB-Co或~(99)MoO_42~-标记 合成FeMo-Co，并使用55Fe和99Mo进行如下步骤 在这条路上。同样，49V在几种蛋白质上积累 FeV-co合成，55Fe和49V将按照以下步骤进行 FEV-CO途径。VnfX最近被确定为一种蛋白质， 在FeV-co合成过程中，V和Fe的积累，以及对 VnfX在FeV-co合成中的作用将是 项目。所有生物体都需要微量元素，而这些信息 在这个项目中取得的成果将增加我们对机制的理解 活细胞通过它同化、积累和区分 用来构建复杂的余因子的痕量元素 许多氧化还原反应对细胞至关重要。人类的健康取决于 适当代谢和利用微量元素，如那些 在本研究中进行了调查。

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 nif-encoded, molybdenum nitrogenase is the iron-molybdenum cofactor, FeMo-co. The vnf-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 99MoO42- during the in vitro synthesis of FeMo-co, and 55Fe and 99Mo will be used to follow the steps in the pathway. Likewise, 49V accumulates on several proteins during FeV-co synthesis, and 55Fe and 49V 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.