PMID:10227138

Citation	Liu, HP, Takio, S, Satoh, T and Yamamoto, I (1999) Involvement in denitrification of the napKEFDABC genes encoding the periplasmic nitrate reductase system in the denitrifying phototrophic bacterium Rhodobacter sphaeroides f. sp. denitrificans. Biosci. Biotechnol. Biochem. 63:530-6
Abstract	Seven genes, napKEFDABC, encoding the periplasmic nitrate reductase system were cloned from the denitrifying phototrophic bacterium Rhodobacter sphaeroides f. sp. denitrificans IL106. Two transmembrane proteins, NapK and NapE, an iron-sulfur protein NapF, a soluble protein NapD, a catalytic subunit of nitrate reductase precursor NapA, a soluble c-type diheme cytochrome precursor NapB, and a membrane-anchored c-type tetraheme cytochrome NapC were deduced as the gene products. Every mutant in which each nap gene was disrupted by omega-cassette insertion lost nitrate reductase activity as well as the ability of cells to grow with nitrate under anaerobic-dark conditions. A transconjugant of the napD-disrupted mutant with a plasmid bearing the napKEFDABC genes recovered both nitrate reductase activity and nitrate-dependent anaerobic-dark growth of cells. Denitrification activity, which was not observed in the napD mutant, was also restored by the conjugation. These results indicate that the periplasmic nitrate reductase encoded by the napKEFDABC genes is the enzyme responsible for denitrification in this phototroph, although the presence of a membrane-bound nitrate reductase has been reported in the same strain.
Links	PubMed
Keywords	Cloning, Molecular; Conjugation, Genetic; DNA Transposable Elements; DNA, Bacterial/genetics; Genes, Bacterial; Mutation; Nitrate Reductases/biosynthesis; Nitrate Reductases/genetics; Nitrate Reductases/metabolism; Plasmids; Rhodobacter sphaeroides/enzymology; Rhodobacter sphaeroides/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RHOSH:O88111	involved_in	GO:0071941: nitrogen cycle metabolic process	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
RHOSH:O88111		GO:0071941: nitrogen cycle metabolic process	ECO:0000315:		P		Table 3. Genes napKEFDABC were determined to be involved in denitrification in an experiment that measured gases released by four strains: wild-type, nap-bearing, napD-deficient mutant and non-nap bearing mutant that conjugated with another bacterium containing napKEFDABC. Wild-type strain produced gases which showed denitrification activity. napD deficient strain as well as non-nap bearing strain produced no gases and therefore no denitrification activity. Nap-deficient mutant that conjugated with nap-bearing bacterium regained denitrification activities.	complete CACAO 2620

References

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