title: Regulation of nitrogenase A and R concentrations in Rhodopseudomonas capsulata by glutamine synthetase.
abstract: Nitrogen-starved purple non-sulphur bacteria have an active unregulated form of nitrogenase (nitrogenase A); however, the nitrogenase of a glutamine synthetase-negative mutant of Rhodopseudomonas capsulata, when nitrogen-starved, was predominantly inactive and required activation by Mn2+ and activating-factor protein. This regulatory form of nitrogenase has been called nitrogenase R. Treatment of wild-type cells (containing nitrogenase A) with methionine sulphoximine, an inhibitor of glutamine synthetase, converted the enzyme into nitrogenase R. Glutamine synthetase thus appears to control the intracellular concentrations of nitrogenase A and R and in this way regulates nitrogenase activity in the photosynthetic bacterium.
mesh_terms: D004789:Enzyme Activation / Q000187:drug effects; D005974:Glutamate-Ammonia Ligase / Q000494:pharmacology*; D007700:Kinetics; D008345:Manganese; D008717:Methionine Sulfoximine / Q000494:pharmacology; D009154:Mutation; D009591:Nitrogenase / Q000378:metabolism*; D012241:Rhodopseudomonas / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D008717:Methionine Sulfoximine; D008345:Manganese; D009591:Nitrogenase; D005974:Glutamate-Ammonia Ligase