CASCADE REGULATION OF THE 2 CBP FNR-RELATED TRANSCRIPTIONAL REGULATORS (ANR AND DNR) AND THE DENITRIFICATION ENZYMES IN PSEUDOMONAS-AERUGINOSA/

ANR, an analogue of Escherichia coil FNR, has been shown to be necessa ry for denitrification, arginine deiminase activity and cyanide produc tion of Pseudomonas aeruginosa. Another CRP/FNR-related regulator, DNR , has also been shown to be necessary for denitrification. In this stu dy, we have found that the transcription of the dnr gene is under the control of ANR. When the dnr gene was expressed by tao promoter in an anr mutant, the strain recovered the ability to grow under anaerobic c onditions by denitrification. Nitrate, nitrite, nitric oxide and nitro us oxide reducing activities were expressed, and the structural genes for nitrite and nitric oxide reductases were transcribed under anaerob ic conditions in the anr mutant strain transformed with the dnr gene. These findings suggest that the expression of the denitrification syst em is controlled not directly by ANR but indirectly via DNR. The argin ine deiminase activity and cyanide production were not regulated by DN R.