title: Nitrogenase structural genes are unlinked in the nonlegume symbiont Parasponia rhizobium.
abstract: Several Rhizobium strains are capable of biological nitrogen fixation in symbiotic association with nonleguminous plants. The gene encoding the iron-protein component of nitrogenase (nifH) from one such strain, Parasponia Rhizobium sp. ANU289, has been isolated and completely sequenced. Unlike previously studied nitrogen-fixing prokaryotes, the Fe-protein subunit is encoded on a separate operon from other components of the nitrogenase enzyme complex. Comparative analysis of Fe-protein amino acid sequences indicates that the symbiotic nitrogen fixation phenotype in Rhizobium may have arisen on at least two separate occasions during its evolution.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005796:Genes; D009591:Nitrogenase / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D012231:Rhizobium / Q000201:enzymology* / Q000235:genetics; D013559:Symbiosis
chemical_list: D009591:Nitrogenase; D004262:DNA Restriction Enzymes