title: 6-cyanopurine, a color indicator useful for isolating mutations in the nif (nitrogen fixation) genes of Klebsiella pneumoniae.
abstract: 6-Cyanopurine (6-CP) can be used as a color indicator for certain classes of nif (N2 fixation) mutations in Klebsiella pneumoniae. Under N2-fixing conditions, Nif+ colonies and most Nif- colonies are purple on media containing 6-CP. Twenty-two Nif- mutants with altered color on medium containing 6-CP were isolated. All white mutants contained mutations in the regulatory genes, nifAA-nifL. Mutants which were more darkly colored than the wild type had mutations distributed among six nif genes. Medium with 6-CP was used to isolate Nif- mutants with deletions internal to the nif genes, and 6-CP was used to identify strains depressed for nitrogenase synthesis in the presence of NH4+.
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D005796:Genes; D005809:Genes, Regulator; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009570:Nitriles; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000096:biosynthesis; D011687:Purines
chemical_list: D009570:Nitriles; D011687:Purines; C018030:6-cyanopurine; D009591:Nitrogenase