title: Reiteration of genes involved in symbiotic nitrogen fixation by fast-growing Rhizobium japonicum.
abstract: By using cloned Rhizobium meliloti nodulation (nod) genes and nitrogen fixation (nif) genes, we found that the genes for both nodulation and nitrogen fixation were on a plasmid present in fast-growing Rhizobium japonicum strains. Two EcoRI restriction fragments from a plasmid of fast-growing R. japonicum hybridized with nif structural genes of R. meliloti, and three EcoRI restriction fragments hybridized with the nod clone of R. meliloti. Cross-hybridization between the hybridizing fragments revealed a reiteration of nod and nif DNA sequences in fast-growing R. japonicum. Both nif structural genes D and H were present on 4.2- and 4.9-kilobase EcoRI fragments, whereas nifK was present only on the 4.2-kilobase EcoR2 fragment. These results suggest that the nif gene organizations in fast-growing and in slow-growing R. japonicum strains are different.
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005796:Genes; D005798:Genes, Bacterial; D009586:Nitrogen Fixation; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012231:Rhizobium / Q000235:genetics* / Q000378:metabolism; D013559:Symbiosis
chemical_list: D004262:DNA Restriction Enzymes