Manganese, an Essential Trace Element for N2 Fixation by Rhodospirillum rubrum and Rhodopseudomonas capsulata: Role in Nitrogenase Regulation

摘要: Nitrogenase (N(2)ase) from the photosynthetic bacterium Rhodospirillum rubrum can exist in two forms, an unregulated form (N(2)ase A) and a regulatory R), latter being identified vitro by its need for activation Mn(2+)-dependent N(2)ase activating system. The physiological significance of this system was suggested here observations that growth R. Rhodopseudomonas capsulata on N(2) gas (a condition produces active R) required Mn(2+), but ammonia or glutamate did not. Manganese could not be shown to biosynthesis either nitrogenase glutamine synthetase turnover, it N(2)ases glutamate-grown cells. Chromatium N(2)ase, contrast, always fully require Mn(2+) activation, suggesting only purple nonsulfur bacteria are capable controlling their activity new type Although substitute Fe(2+) vivo fixation process, and, lesser extent, Co(2+) N(2)ase. Electron paramagnetic resonance spectroscopy buffer-washed chromatophores showed lines characteristic Mn(2+). Removal factor salt wash removed 90% which specific coupling metal factor. data presented all indicate plays important role regulating process these bacteria.