Expression of nrdA and nrdB genes of Escherichia coli is decreased under anaerobiosis

By using plasmid nrdA-lacZ, nrdAB-lacZ, and nrdB-lacZ gene fusions, the expression of nrdA and nrdB genes of Escherichia coli under anaerobiosis has been studied. The results obtained show that cells of E. coli growing under either fermentative or nitrate respiring conditions present a lower basal level of both nrdA and nrdB genes transcription from the nrdPA promoter. On the other hand, transcription of the nrdB gene from the internal nrdPB promoter was not affected by the absence of oxygen. Moreover, the DNA damage-mediated inducing factor of these nrd genes was the same in both aerobic and anaerobic cultures. © 1991.