Identification and characterization of the two-component NtrY/NtrX regulatory system in Azospirillum brasilense
Braz. j. med. biol. res
;
35(6): 651-661, June 2002. ilus, tab
Article
in English
| LILACS
| ID: lil-309516
ABSTRACT
Two Azospirillum brasilense open reading frames (ORFs) exhibited homology with the two-component NtrY/NtrX regulatory system from Azorhizobium caulinodans. These A. brasilense ORFs, located downstream to the nifR3ntrBC operon, were isolated, sequenced and characterized. The present study suggests that ORF1 and ORF2 correspond to the A. brasilense ntrY and ntrX genes, respectively. The amino acid sequences of A. brasilense NtrY and NtrX proteins showed high similarity to sensor/kinase and regulatory proteins, respectively. Analysis of lacZ transcriptional fusions by the ß-galactosidase assay in Escherichia coli ntrC mutants showed that the NtrY/NtrX proteins failed to activate transcription of the nifA promoter of A. brasilense. The ntrYX operon complemented a nifR3ntrBC deletion mutant of A. brasilense for nitrate-dependent growth, suggesting a possible cross-talk between the NtrY/X and NtrB/C sensor/regulator pairs. Our data support the existence of another two-component regulatory system in A. brasilense, the NtrY/NtrX system, probably involved in the regulation of nitrate assimilation
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Bacterial Proteins
/
Azospirillum brasilense
/
Gene Expression Regulation, Bacterial
/
Nitrogen Fixation
Type of study:
Diagnostic study
Country/Region as subject:
South America
/
Brazil
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2002
Type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal do Paraná/BR
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