Requirement of NifX and Other nif Proteins for In Vitro Biosynthesis of the Iron-Molybdenum Cofactor of Nitrogenase
| Autor: | Paul W. Ludden, Ronda M. Allen, Priya Rangaraj, Gary P. Roberts, Vinod K. Shah, Jon T. Roll, Ranjini Chatterjee |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 1999 |
| Předmět: |
Azotobacter vinelandii
Molybdoferredoxin biology Cell-Free System Physiology and Metabolism chemistry.chemical_element Nitrogenase Molybdate biology.organism_classification Microbiology Small molecule Cofactor Cell-free system chemistry.chemical_compound chemistry Biochemistry Biosynthesis Bacterial Proteins Molybdenum Genes Bacterial Nitrogen Fixation biology.protein Molecular Biology |
| Popis: | The iron-molybdenum cofactor (FeMo-co) of nitrogenase contains molybdenum, iron, sulfur, and homocitrate in a ratio of 1:7:9:1. In vitro synthesis of FeMo-co has been established, and the reaction requires an ATP-regenerating system, dithionite, molybdate, homocitrate, and at least NifB-co (the metabolic product of NifB), NifNE, and dinitrogenase reductase (NifH). The typical in vitro FeMo-co synthesis reaction involves mixing extracts from two different mutant strains of Azotobacter vinelandii defective in the biosynthesis of cofactor or an extract of a mutant strain complemented with the purified missing component. Surprisingly, the in vitro synthesis of FeMo-co with only purified components failed to generate significant FeMo-co, suggesting the requirement for one or more other components. Complementation of these assays with extracts of various mutant strains demonstrated that NifX has a role in synthesis of FeMo-co. In vitro synthesis of FeMo-co with purified components is stimulated approximately threefold by purified NifX. Complementation of these assays with extracts of A. vinelandii DJ42.48 (Δ nifENX ΔvnfE ) results in a 12- to 15-fold stimulation of in vitro FeMo-co synthesis activity. These data also demonstrate that apart from the NifX some other component(s) is required for the cofactor synthesis. The in vitro synthesis of FeMo-co with purified components has allowed the detection, purification, and identification of an additional component(s) required for the synthesis of cofactor. |
| Databáze: | OpenAIRE |
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