title: Electron transport to nitrogenase in Klebsiella pneumoniae: purification and properties of the nifJ protein.
abstract: In Klebsiella pneumoniae, the physiological electron flow to nitrogenase involves specifically, in addition to nitrogenase reductase, the products of the nifF and nifJ genes. The J protein was purified to homogeneity and was found to be an iron-sulfur protein devoid of molybdenum. In its native state, the J protein is a dimer of Mr about 245 000, made up of two subunits of the same molecular weight. It contains about 30 mol iron and 24 mol labile sulfur/mol protein. The addition of J protein to crude extracts of a nifJ mutant reestablishes pyruvate-supported acetylene-reducing activity. This activity is further enhanced by addition of pure nitrogenase (Kp1). Based on its physical properties, the J protein is probably an oxidoreductase whose physiological role might be to transfer electrons from a metabolic donor to the F protein. In addition, another protein whose activity is also dependent on the nifJ gene seems to be required for the formation of a fully active Kp1.
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004579:Electron Transport; D005798:Genes, Bacterial; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism*; D009591:Nitrogenase / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D009591:Nitrogenase