The control of @entity47511 nifA expression in response to @entity26 and @entity3265 involves FixLJ, FixK, NtrBC, NtrXY and the HF-I-like protein NrfA. The regulation is thus complex and possibly involves post-transcriptional regulation by NrfA. The coding region of nifA was determined using a translational lacZ fusion and by site-directed mutagenesis to identify which of four in frame AUG codons was used. The major NifA protein is translated from the second AUG codon and is predicted to consist of 613 @entity1522 . Primer extension analysis showed a major transcript starting 34 bp downstream from the anaerobox in wild-type, nifA, rpoN, ntrC and nrfA strains, but not in a fixK mutant. FixK- and @entity26 -dependent transcription of nifA was confirmed by the analysis of four transcriptional nifA-lacZ fusions with fusion junctions at positions +1, +47, +110 and +181 with respect to the start site. Regulation by @entity3265 was independent of FixK and RpoN, NtrC being only partially required. Thus, there may be another type of @entity1568 control that does not involve NtrC in A. caulinodans. NrfA is not required for the initiation of nifA transcription but, most probably, has an effect on nifA mRNA stability and/or translation. NrfA also restores the defect in rpoS translation to an @entity526 hfq mutant, indicating that HF-I and NrfA have similar activities in both A. caulinodans and @entity526 .

The control of @entity47511 nifA expression by @entity26 , XXXX and by the HF-I-like protein, NrfA.

@entity1522 :: ('CHEBI:33709', 'Chemical') :: ['amino acids'] @entity1568 :: ('MESH:D009584', 'Chemical') :: ['nitrogen'] @entity3265 :: ('MESH:D000641', 'Chemical') :: ['ammonia'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity47511 :: ('7', 'Species') :: ['Azorhizobium caulinodans'] @entity526 :: ('562', 'Species') :: ['Escherichia coli', 'E. coli']
@entity3265 :: (MESH:D000641,Chemical) :: ['ammonia']
