The cloning and functional characterization of the nifH gene of Rhodospirillum rubrum.

Dinitrogenase reductase (the nifH product) from Rhodospirillum rubrum is regulated by a post-translational modification system encoded by draTG. As demonstrated in this report, the cloning, sequencing, and functional characterization of the nifH gene provides a basis for further analysis as well as revealing interesting features of gene organization. The coding regions of nifH and draT are separated by only 400 bp, though the genes are divergently transcribed and differentially regulated. The construction of a nifH insertion caused a Nif- phenotype and destroyed the mutant's ability to synthesize both dinitrogenase and dinitrogenase reductase, verifying functionality and transcriptional organization of the nifHDK genes.