Involvement of fixLJ in the regulation of nitrogen fixation in Azorhizobium caulinodans

Mol Microbiol. 1991 Mar;5(3):665-73. doi: 10.1111/j.1365-2958.1991.tb00738.x.


A gene bank of Azorhizobium caulinodans DNA constructed in the bacteriophage lambda GEM11 was screened with Rhizobium meliloti fixL and fixJ genes as probes. One positive recombinant phage, ORS lambda L, was isolated. The nucleotide sequence of a 3.7 kb fragment was established. Two open reading frames of 1512bp and 613bp were identified as fixL and fixJ. Kanamycin cartridges were inserted into the cloned fixL and fixJ genes and recombined into the host genome. The resulting mutants were Nif- Fix-, suggesting that the two genes were required for symbiotic nitrogen fixation and for nitrogen fixation in the free-living state. Using pnifH-lacZ and pnifA-lacZ fusions, it was shown that the FixLJ products controlled the expression of nifH and nifA in bacteria grown in the free-living state.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Base Sequence
  • Cloning, Molecular
  • DNA Probes
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial*
  • Hemeproteins / chemistry
  • Hemeproteins / genetics
  • Histidine Kinase
  • Molecular Sequence Data
  • Mutation
  • Nitrogen Fixation / genetics*
  • Nucleic Acid Hybridization
  • Phenotype
  • Rhizobiaceae / genetics*
  • Rhizobiaceae / metabolism
  • Rhizobium / genetics


  • Bacterial Proteins
  • DNA Probes
  • Hemeproteins
  • FixJ protein, Bacteria
  • FixL protein, Bacteria
  • Histidine Kinase

Associated data

  • GENBANK/S77307
  • GENBANK/X52368
  • GENBANK/X52369
  • GENBANK/X52370
  • GENBANK/X52371
  • GENBANK/X52372
  • GENBANK/X56658
  • GENBANK/X56742
  • GENBANK/X58355
  • GENBANK/X59272