title: Complementation analysis of Klebsiella pneumoniae mutants defective in nitrogen fixation.
abstract: A series of mutants defective in nitrogen fixation (nif) were isolated in Klebsiella pneumoniae strain M5a1. The nif mutations were either located on plasmid pRD1 or on the K. pneumoniae chromosome. A total of 37 plasmid mutants and 28 chromosomal mutants were employed in complementation tests using the acetylene reduction technique. Most mutants could be assigned to one of seven nif cistrons: nifA, nifB, nifD, nifE, nifF, nifH, and nifK. Complementation analysis of two nif deletion mutants confirmed transductional evidence that these strains carry nifB-A-F deletions. One deletion mutant had, in contrast to previous transductional analysis, a functional nifK cistron and presumably is deleted for nifB-A-F-E. Examination of the biochemical phenotype of several mutants suggests that the nifA product has a regulatory function, and nifK, nifD and nifH are most probably the structural genes for nitrogenase.
mesh_terms: D002876:Chromosomes, Bacterial; D005796:Genes; D005816:Genetic Complementation Test; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics*; D009154:Mutation; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000235:genetics; D010641:Phenotype; D010957:Plasmids; D014161:Transduction, Genetic
chemical_list: D009591:Nitrogenase