Mutational analysis of the Klebsiella pneumoniae nitrogenase promoter: sequences essential for positive control by nifA and ntrC (glnG) products.
AUTOR(ES)
Ow, D W
RESUMO
ntr (nitrogen regulated) and nif (nitrogen fixation) promoters are structurally similar to each other but bear no resemblance to canonic Escherichia coli promoters. ntr promoters are normally activated by the ntrC (glnG) product, but they can also be activated by the ntrC-related Klebsiella pneumoniae nifA product. In contrast, nif promoters of K. pneumoniae such as the nitrogenase (nifH) promoter can only be nifA activated. In this paper, we report the isolation and characterization of 28 mutants of the K. pneumoniae nifH promoter. Class A mutants no longer respond to nifA-mediated transcription, and class B mutants can now respond to ntrC-mediated activation. These two classes of mutants define sequences important to nifA- and ntrC-mediated transcription. Most surprising is that a single base change is sufficient to convert a nifA-activated promoter into an ntrC-activated one.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=214977Documentos Relacionados
- Deletion analysis of the Klebsiella pneumoniae nitrogenase promoter: importance of spacing between conserved sequences around positions -12 and -24 for activation by the nifA and ntrC (glnG) products.
- Promoters regulated by the glnG (ntrC) and nifA gene products share a heptameric consensus sequence in the -15 region.
- Nitrogen control of the nif regulon in Klebsiella pneumoniae: involvement of the ntrA gene and analogies between ntrC and nifA.
- NtrC is required for control of Klebsiella pneumoniae NifL activity.
- Activation of the Klebsiella pneumoniae nifU promoter: identification of multiple and overlapping upstream NifA binding sites.