Regulation of nitrogenase activity by covalent modification in Chromatium vinosum.
Nitrogenase in Chromatium vinosum was rapidly, but reversibly inhibited by NH4+. Activity of the Fe protein component of nitrogenase required both Mn2+ and activating enzyme. Activating enzyme from Rhodospirillum rubrum could replace Chromatium chromatophores in activating the Chromatium Fe protein, and conversely, a protein fraction prepared from Chromatium chromatophores was effective in activating R. rubrum Fe protein. Inactive Chromatium Fe protein contained a peptide covalently modified by a phosphate-containing molecule, which migrated the same in SDS-polyacrylamide gels as the modified subunit of R. rubrum Fe protein. In sum, these observations suggest that Chromatium nitrogenase activity is regulated by a covalent modification of the Fe protein in a manner similar to that of R. rubrum.
D000641:Ammonia / Q000494:pharmacology; D002844:Chromatium / Q000201:enzymology* / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D008345:Manganese / Q000494:pharmacology; D009586:Nitrogen Fixation / Q000187:drug effects; D009591:Nitrogenase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects
D008345:Manganese; D000641:Ammonia; D009591:Nitrogenase