Studies on the regulation and function of the Klebsiella pneumoniae ntrA gene

The ntrA gene from Klebsiella pneumoniae has been cloned and the product identified as a 76-kDal acidic polypeptide. An ntrA::lacZ fusion was used to demonstrate that expression of ntrA is not controlled by the nitrogen regulation (ntr) system and is independent of the nitrogen status of the cell. Studies with multicopy plasmids carrying ntrA and rpoD suggest that the ntrA product competes with the rpoD product (sigma 70 of RNA polymerase) in mediating transcription initiation by RNA polymerase at ntrA-dependent promoters. No significant homology between ntrA and rpoD was detected by Southern blotting.