Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation
| Autor: | N Michel-Reydellet, Claudine Elmerich, N. Desnoues, P A Kaminski |
|---|---|
| Přispěvatelé: | Physiologie Cellulaire, Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), N.M.-R. is a recipient of a predoctoral fellowship from the Ministère de l’Enseignement Supérieur et de la Recherche. |
| Rok vydání: | 1997 |
| Předmět: |
Operon
MESH: Genes Regulator PII Nitrogen Regulatory Proteins Molecular Sequence Data Mutant MESH: Amino Acid Sequence MESH: Base Sequence MESH: Nitrogen Fixation Microbiology Bacterial Proteins Glutamate-Ammonia Ligase Rhizobiaceae Nitrogen Fixation Glutamine synthetase Genes Regulator MESH: Glutamate-Ammonia Ligase MESH: Cloning Molecular Amino Acid Sequence Cloning Molecular MESH: Bacterial Proteins MESH: Rhizobiaceae Molecular Biology MESH: PII Nitrogen Regulatory Proteins MESH: Gene Expression Regulation Bacterial MESH: Molecular Sequence Data Base Sequence biology Structural gene Nitrogenase Gene Expression Regulation Bacterial biology.organism_classification [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology Biochemistry Genes Bacterial Azorhizobium caulinodans rpoN Pii nitrogen regulatory proteins MESH: Genes Bacterial Research Article |
| Zdroj: | Journal of Bacteriology Journal of Bacteriology, 1997, 179 (11), pp.3580-3587. ⟨10.1128/jb.179.11.3580-3587.1997⟩ |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.179.11.3580-3587.1997 |
| Popis: | International audience; The nucleotide sequence and transcriptional organization of Azorhizobium caulinodans ORS571 glnA, the structural gene for glutamine synthetase (GS), and glnB, the structural gene for the P(II) protein, have been determined. glnB and glnA are organized as a single operon transcribed from the same start site, under conditions of both nitrogen limitation and nitrogen excess. This start site may be used by two different promoters since the expression of a glnB-lacZ fusion was high in the presence of ammonia and enhanced under conditions of nitrogen limitation in the wild-type strain. The increase was not observed in rpoN or ntrC mutants. In addition, this fusion was overexpressed under both growth conditions, in the glnB mutant strain, suggesting that P(II) negatively regulates its own expression. A DNA motif, similar to a sigma54-dependent promoter consensus, was found in the 5' nontranscribed region. Thus, the glnBA operon seems to be transcribed from a sigma54-dependent promoter that operates under conditions of nitrogen limitation and from another uncharacterized promoter in the presence of ammonia. Both glnB and glnBA mutant strains derepress their nitrogenase in the free-living state, but only the glnBA mutant, auxotrophic for glutamine, does not utilize molecular nitrogen for growth. The level of GS adenylylation is not affected in the glnB mutant as compared to that in the wild type. Under symbiotic conditions, the glnB and glnBA mutant strains induced Fix- nodules on Sesbania rostrata roots. P(II) is the first example in A. caulinodans of a protein required for symbiotic nitrogen fixation but dispensable in bacteria growing in the free-living state. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|