Transcriptional activation of the nitrogenase promoter in vitro: Adenosine nucleotides are required for inhibition of NIFA activity by NIFL
| Autor: | T. Eydmann, Richard A. Dixon, Susan Hill, S. Austin, E. Söderbäck, T. Jones |
|---|---|
| Předmět: |
DNA
Bacterial Transcription Genetic Molecular Sequence Data Guanosine triphosphate Biology Microbiology chemistry.chemical_compound Bacterial Proteins Transcription (biology) Sigma factor Adenine nucleotide Nitrogen Fixation RNA polymerase Nitrogenase Nucleotide Promoter Regions Genetic Molecular Biology chemistry.chemical_classification Azotobacter vinelandii Base Sequence Adenine Nucleotides Promoter DNA-Directed RNA Polymerases biochemical phenomena metabolism and nutrition Nucleoside-Triphosphatase biology.organism_classification Acid Anhydride Hydrolases Nucleoproteins chemistry Biochemistry Nucleic Acid Conformation bacteria Guanosine Triphosphate Rifampin Oxidoreductases Protein Binding Transcription Factors Research Article |
| Zdroj: | Scopus-Elsevier |
| Popis: | The enhancer-binding protein NIFA is required for transcriptional activation of nif promoters by the alternative holoenzyme form of RNA polymerase, which contains the sigma factor sigma 54 (sigma N). NIFA hydrolyzes nucleoside triphosphates to catalyze the isomerization of closed promoter complexes to transcriptionally competent open complexes. The activity of NIFA is antagonized by the regulatory protein NIFL in response to oxygen and fixed nitrogen in vivo. We have investigated the requirement for nucleotides in the formation and stability of open promoter complexes by NIFA and inhibition of its activity by NIFL at the Klebsiella pneumoniae nifH promoter. Open complexes formed by sigma 54-containing RNA polymerase are considerably more stable to heparin challenge in the presence of GTP than in the presence of ATP. This differential stability is most probably a consequence of GTP being the initiating nucleotide at this promoter. Adenosine nucleosides are specifically required for Azotobacter vinelandii NIFL to inhibit open complex formation by native NIFA, and the nucleoside triphosphatase activity of NIFA is strongly inhibited by NIFL under these conditions. We propose a model in which NIFL modulates the activity of NIFA via an adenosine nucleotide switch. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|