Activation of a consensus FNR-dependent promoter by DNR of Pseudomonas aeruginosa in response to nitrite.

Expression of the enzymes for anaerobic nitrate respiration of Pseudomonas aeruginosa requires two CRP/FNR-related transcriptional regulators, ANR and DNR. Activity of the consensus CRP- or FNR-dependent promoter in the anr and dnr deficient mutants was investigated. The CRP-dependent promoter was active in the mutant strains. Both regulators could activate the promoter with a consensus FNR-binding motif. DNR-dependent activation was nitrite-dependent, whereas activation by ANR was not, suggesting that only DNR is involved in sensing nitrogen oxides.