Regulation of nitrogenase in the photosynthetic bacterium Rhodopseudomonas capsulata as studied by two-dimensional gel electrophoresis.

By using two-dimensional electrophoresis, five putative soluble nif gene products were identified, and the regulation of nif gene expression in Rhodopseudomonas capsulata was investigated. Expression of nif was repressed by ammonia and atmospheric concentrations of oxygen. Deprivation of molybdenum caused an interesting pattern of partial repression of nif gene expression that was not relieved by tungsten. These results are discussed in relation to the better understood system of nif regulation in Klebsiella pneumoniae.