title: Regulation of nitrogenase biosynthesis in Klebsiella pneumoniae: effect of nitrate.
abstract: The rate of biosynthesis of nitrogenase polypeptides in Klebsiella pneumoniae was determined in a medium containing NaNO3 or NaNO2. Nitrogenase biosynthesis was completely repressed by NO3- in a mutant strain, strain SK-25, that is derepressed for nitrogenase biosynthesis in the presence of NH4+. Chlorate-resistant mutants, derived from strain SK-25, that are defective in NO3- respiration produced nitrogenase in the presence of NO3-. Strain SK-56), a chlorate-resistant derivative capable of NO3- respiration, produced no nitrogenase in the presence of NO3- or NO2-. Klebsiella pneumoniae respired under anaerobic conditions utilizing either NO3- or NO2- as terminal electron acceptor. A mechanism for the control of nitrogenase biosynthesis is discussed involving the redox control of anaerobic enzyme systems.
mesh_terms: D000693:Anaerobiosis; D001386:Azides / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004794:Enzyme Repression / Q000187:drug effects; D005560:Formate Dehydrogenases / Q000096:biosynthesis; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics; D009154:Mutation; D009566:Nitrates / Q000494:pharmacology*; D009573:Nitrites / Q000494:pharmacology; D009591:Nitrogenase / Q000096:biosynthesis*
chemical_list: D001386:Azides; D009566:Nitrates; D009573:Nitrites; D005560:Formate Dehydrogenases; D009591:Nitrogenase