BIOSYNTHESES OF FEMOCO AND FEVCO OF NITROGENASE

固氮酶将N2转化为铵，铵是氮的一种形式。 更容易获得人类营养。 在活性位点 钼固氮酶是铁-钼辅因子， vnf编码的固氮酶含有结构相似的 铁钒辅因子，FeV-co。本项目的总体目标是 确定了FeMo-co和FeV-co的生物合成途径， 固氮原核生物棕色固氮菌。 nifBUSV基因 合成两种辅因子都需要产物。 此外该 合成FeMo-Co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基因产物用于FeV-co的合成。 该项目的目标是确定这些基因产物在以下方面的作用： FeMo-co/FeV-co的合成，并为制备FeMo-co/FeV-co复合材料奠定了基础。 在每个辅因子的合成过程中对Mo或V的特异性。 NifB-co NifB的代谢产物，是FeMo-co和FeV-co的Fe和S供体; 确定NifB-co的结构是本项目的目标。 FeMo-co合成途径中的几种蛋白质，包括NifH 在体外过程中积累来自55Fe-NifB-co或来自99MoO 42-的标记 合成FeMo-Co，55Fe和99Mo将用于后续步骤 在通道中。 同样，49V在几种蛋白质上积累， FeV-co合成，并且55Fe和49V将用于以下步骤： FeV-co途径。 VnfX最近被鉴定为一种蛋白质， 在FeV-Co合成过程中积累了V和Fe， VnfX在FeV-co合成中的作用将是本发明的主要目标。 项目 所有生物都需要微量元素， 在这个项目中获得的将增加我们对机制的理解， 活细胞吸收、积累和区分 微量元素，用于构建复杂的辅因子， 许多对细胞至关重要的氧化还原反应。 人类健康取决于 适当的代谢和利用微量元素，如那些 在这项研究中调查。

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.